he Ft ny

Pere Se © ye ee
oe. et revere

~~
ee wor
:

noo em ¥ - . vee 7 - rrreey

Verret ve ¥ER re Adin notin = never
; a ~~" ee ar “

wv aint - ree

Soper ;

at

call \! Vuk
My wy " akan

| i
a

=p bebe

| :
ae aad
Pad ww VO”

jw

|

syatiycres weeny ae

AH “Uv : $e UU |

{
j ie
; 4

beri tst ie CAP

ve

/ ww
Fie be PA
|

/
be]
ee BO Re
i wo

i

CU My
|
V

. | | —_)
ou iY

I | had fo A | iv / ed { aaa Rl
Ue bd ’ ; A } bud { Ye ey

sill

QUES Mal iy

i 2 Soe
ifeeed Yes \
H 4 ; !
j 7 } j ‘ tects
{ 1 } | ; } j 3
; ; { j i} He}
} \ i |
re A : | j ; J wey
OS frag foes 1 j
| f \ , | 1 | )

ORE ES Rie SL
gare

|

Eee a
nye w
Hb obh

i Ut

Det!
Mn Ph
i ity

Mies

Hh) oa
PP) hes Lv

Me ‘ORT e ey
Fee rae Xu i,

a)

im i
haat
mae Am

utah
mM
ah 8.

. , ty 4) al ard
i i a ¢ MtY fi a h fh
Y ee At #
h i a ! ' bi i Al be Hibs
i Me ie eal”: : Vy ah PER?
{

pe
i Hh
mie

a TAG

Wale

al

ee a
> oo.

mgt
ae
= ¥
na
aes
YA

; Ye. Pa! bul -
j j a
i ; pit
: PM
4
’ f a
; , ,
wf aN y r
at he Vi @ ny
ey i «
w. hk
We : ay,. vay P
hog
i ' A
Wh |
aa:
ah _-
sae
ar ‘
as" “
eee
" ¥ \
gi. \
. U]
? .
a as 2 .
ws *
i }
7
rs
i ws y
' ‘
bot :
ur’.
1 P' » a a
i mie
4h) bh ?
2 “ te &
i cA a :
; ce. §
Tie
i |
7 ) ;

al ‘ ~4r
y j we
ne as |
"n
: ' \
7 Bs

y Sp
Te r i

= * j

‘i

UNS ith)
ya a |
6

ai! eo

Ki
et

t
i oA
re ab
ft

TWENTY-FOURTH REPORT

OF THE

STATE ENTOMOLOGIST

ON THE

- Noxious and Beneficial Insects

OF THE

-

STATE OF ILLINOIS

|
|
thas BLOOMINGTON:
# 3 PANTAGRAPH PRINTING AND STATIONERY Co.
|

NOV 13%
pe \ @ ) 3 553
~ SMOn “f AY yt
Printers, Binders and Stationers
1908 *
Ape.
La #

Injuries caused by Elm Twig-girdler (Oberea ulmicola Chittenden).

TWENTY-FOURTH REPORT

OF THE

STATE ENTOMOLOGIST

ON THE

Noxious and Beneficial Insects

OF THE

STATE, OF. ILLINOIS

RHAIRTEEN EH REPORT: OF S. A. FORBES

BLOOMINGTON:
PANTAGRAPH PRINTING AND STATIONERY Co.
Printers, Binders and Stationers
1908

CONTENTS.

PAGE

Injury to Corn by the Timothy Bill-bugs (Sphenophorus sp.)............... I
BxniMinatone Or en acedrs Mieldan uae nates enc owes cr os he cae sche soe I
Da Spetist rae OAM iy ee gles arate iereevhacass sp Sree ek oa hoe woah oewees 2
MD Ge MCI OUS SPORES ethyl Heote a ele clort eee cae tidy apices ae tite oe A Lat es 2
Pe init veto eAMMMO EMM Rap nareh aidhc-cacne kone een c Ooh ae Waka eel eb ok 2
bie divining COmOOnM ert. toe ese ccd citsaie sb lotions te eee be nk ie en eas 3
Generale Resuilismoceties Livy tty aetacei tor onan: eee reese ts eo ear gate 3
NSE RECUM@ariea warcle: EF lanit cc. 4, scnas sates ok Leen oe ee eters tn sels 3
JASONS in! DG Ee Eg) DIY on iC aR Pe LA SOM a Ree a 4
POfAle ANTONI OLme liyitys cme eae. es aia sion ano cba ae ea etn nat 4
Statistics of Bill-bug Injury to Corn, Dalbey Field, 1902.................. 6
MethodsSmotesbrev.entionimws. . cis. en cra tae ities aoe eS Bes ee 6
NSRP EAT TNE SS 2 ee 7 Pea ec gt are ag ee tN TS Ceti SR i Re ABO ar UU ate aa mae 7
Field Experiments on the Corn Root-aphis (Aphis maidiradicis Forbes)..... 8
“NE, NSE yer a Wo? bao oy War SU Soo a i ane a ane 8
ihe Galeshuro Cultivation’ Experiment.” “(Table [2.09.2 nets eo 9
iietaarvel- Experiment, -- Ghaple Li) wn sce det ct nek savas woe ae oo ae II
ites Seasoite On 1005.04 bradtord. UMnOIS! .34 Senco. tee strane 2a oe.c cea coe 13
Mies nina Pexperiimenitu sche te oon rue ton Ck ha tiesto wre otdle ve brs cals lee 15
aber hunccan es Mxcperinente casc95 i atickens cies oes os Lokae ba aod oe eee as 19
Siserranons one the wearer ariian «aye es. cokes foo ee Me tee eles 20
Ohsenyationssin-theshompsonpavteldiapwsss nc semen. en sste cc oe heehee 23
Nuditionaleatiscellatecotism ObSetwvattOmSscminaciceiiete to cs oe cients sie cohen meenn 24
Venera MiIsctsston OL the iRestlesian dsc e fo nt hdanciys ehes us «ase sess casey eeiotans 26
Field Experiments for the Protection of Corh against Chinch-bug Injury.... 30
Bain Chat expe mi Clits stm ee aren aatst aateisee ee Gales re A Suals Sn asa ds ale 0 ese 30
SSitiamsineyty/ a Ore ONCISIOIS Nays ee Was Saitee as aie Pa acs 2b wn Lb) babe eee ee Be
WisesoneMerosence Emulsiommanmene cts teas bose eae othe oon dd Soe celeron. 2
hem Carhoncdalecrexperimemty ia ae ndfesescneieleacie we ae eo esis sie ote ae ees)
Bilin eee trorrnepitbe Hs) ENUM TAG gee orice aya et vais cosas chet clo: shale’ otslchore) uel sheretotciodebeleners aumeeten anes 36
Dubois oneMOdite EB xpehimentS Ass: snc Wedd en chee Sates eg eee ee ceo ane 30
Hxperiments witht lurid Insecticides. 2.5... 22 25 204 5 ecw ewes nein se 40
Experiments: with the. Gasoline Blast-lamp.. 5012000. U ce ee. cs eee ee wes 43
Oni thes Satie (OSes Seale nara. sna ae CAS AMA ata bos Hie ate en ae ear 46
On the Harlequin Cabbage-bug SERV OCAY Uitte Vey: Pete aide Ne 48
@nsthe: Cotton Bollaweevile asc a. scoa ee e e ete AQ
ANE LOR ope h ne e plgr or iewia per aihin mae ne bay dae tee A he ee en ee PO kg ee ree 50
Use of the Gasoline Torch against the Chinch-bug....................... 52
cere ie teria hy: Veh sok cS ae Ne a a EE ae eal fac cats <i 56
Comparative Experiments with Various Insecticides for the San Jose Scale.. 59
SUSU Meer ORM MRSHECIONS —2> scence er Meter ee eb ea ricer cocks nes 60
Conditionssnecessary to Exact Experiments 52720 Sac esc s a eevee nes 61
Orioisiaisearpose Of Operations. <1... set see tt bea teh sede tess swale ess be eee 62

MostaGeneralehesiults 1.0. ve.cp nus. nce aeemrore rte ete eons int oe ek Satpale os 62

PAGE
‘The Lime. and sulphur “Mixtures ©...\: (2. :< Seco tie ee ees 63
Major. Bscperiments 2... co 6 els. Po be eee ee ee 63
GeneralsResults ofthe Eixpesimients. .< :.<.0c. 4. aa toe ee oe ee FAL
Minor Kaperments ! 255.2 es Use Des noc 8 eatin Oo ee ee 72
Miscellaneous “Additional Insecticides <2... 22.0 ae tee eee eee 73
WOSENOte Miatentals cre cssteee die Ones Tine lan oa the d Dereon ee ee 74
(Getletal Siiinigaa ty acs vias .1i wlSpe.e'lcce 24 wig adie bs SAe Aten On as, See 76
Spraying Apples for the Plum-curculio.... -. 5... 1. see econ oe eee 78
Some, ater i xperiments pa 54.lse.b so es ess oe le been See 78
Mee nerinrents bly TG04. No. ec s tos Sa oo wreels beidlos © 42 side duane oul UAE ae 80
RESHIS “OF “Hoxpeniments. rr suis ok ities Bek oe bu nace.» clo Deis Se Aer ee 82
Gost Ors thea CPeratiOnirrae tere lee aia Stn alee cs we lve Sede Rie Cee gI
Summary. Jol opravinewINestltsupeemnc i eisecrie karin oor acts sloth neeree aaa 92
Roronelests wok Sprayed cApplesm merrier ei teser sae teecis stinks nice 5 ee ee 92
inhe@NeutraleZonesms Spraying. x periment si a. cncrierseyaer ones sei tee rele O04
Diagram of Spraying Effects with Arsenate of Lead.................... gs
‘ire \Cottony Maple Scalevinllbimois scares ce cia eer Mere ae aires 10)
GOCE Aarits Resists Rrteeee cone arcs ee OR re ete Tiers ee ee Eee et ee Tals Sera 103
hewate Fistoryeor the Lnsect cx wre nes 2 co emt potaer rae eae cae 104
Wher atehingy eti0 Gest x co cate toc rerio eee ea eee eae 106
Summer sl nsecticide “Measures ceesccstecn cits ce ie choc aie acie oie one eae cae 106
Bihectssobseaxpermental Simmer, Spiaiwer se. e Gee pies oracle 109
Wanter “Insecticide “Mieastres <4) oxi .Re-acelee c hio en eaeees Ee Td ay Arata 110
Tei ptiesstOr pl CES). ex Sete rene ace eats area re haere aS oo toe EE ee oe 112
TISEELS DALELINES) fray Rit ae itera imino inter Se rictacap ons rohe he, ate ORT ae aca II4
SUITED Vee ieee sear) walter a Se Le ty GTR SI EIR at TOR ane 115
The Elm Twig-girdler, Oberea ulmicola Chittenden...................-+000- 118
COC Tuco Or - MMITIE VE tc scot o enro dete Peciaros.o eran tn horas Oot ee Wee 119
WNaturesand) -Extentwory Injury; <. ssi bisects sets ee oo ae eee ae 120
Leite nElstoryadnid’s etabits’ 2a). tere eet ts aetercet ae ccc toie lowed iets eee ec ee renee 122
Mode of Oviposition .......... OK ME ee MN A Ee Sane or 122
Stas Hip ges der iatee Riviathie eines aye’ Boe ieee dia kare pa ath le Dee ee 123
Whe warvart secs) ce tence Piva ois ater ah okie, On ache oe Ee eee eee 123
he, Pepa wees aioe teen tie slants, cle a daw hee ec Gh ae RS ace eae 125
he “Beetle cieciya cheecn oe ce, srathc orn and ants Maro RRR Eee ear 126
DStribitio ns As sincc ks Cee eo Si ae ee Ee aE aera ae 127
Natural (Checks ony Minltplications..55 -cs se nena ee aoe oe Ror CORE Bate 128
Puderus lividus Ashmeady 3% 8k vadees Aes ae he as Leaner 128
Cymutodera balteata ‘Aseconte. cc. nico a eee 129
Description of Larva dca ceisn tees eee ee oie eka eee ee 130
Frotective’Measafes «0. 00s. 43, clvlyeae aetna ia ealeie ce ae eee 131
MSSCrIptION: . An Wen win « ooteusled Bev dee an ae Soe ne 133
761) | i. be ie eM Roem bee nt We 133
Lt rr a oh a ene IMeR Dire crue Pee le mat mere Ay hth Som) Be 133
Larva Oe PE ATO ome TS Hoe, oleh i, 5 yols cfo cae Sal eee 133
Li ae ee a ee a ne Er a Sec fo 8 ee eB 134
On the Life History, Habits, and Economic Relations of the White-grubs
ana) May-peetles. CLachnosterna). .200..-acea coe ee ee 135
PRE MP CONOUNC SPECIES oui a5 sf ua k Wn sas wah oh Gas See ee ee eee eee 136

me hitstories,ot. the: injurious ,Spectes: ~~... is oe eee 137

Vv -

PAGE

Variation of Numbers in Different Localities and Years................ 140

bended seeding Elapits Of the Species sss. c.c4e. cess, vss e'ula's oie oe cae names 142

Results of Feeding Experiments with May-beetles (Lachnosterna)......143
Comparative Collections of Lachnosterna from Food Plants. Urbana,

Io 0 6 Pape NER eo fc) iy ope ck Bec NMR PERE Sry 5-0 lc eg ALE 144
NMiorationmanda Dispersal: cm sees.) Nas be ROMEO BOR ee OES ate Ses 145
dale [orgie gran! eccer sors [Rta Co pee acy achck beers, bagi a nr ol A ee 150
Rel AtionsatOmVMeabietue <ccnriit cm ccren eceneten eatin ren tae abeneiea lias) ciepeieue's sca eae 154
Modestandublaces- or Elibernationiisseta.s se oie a ePaieiersee «asus oe seis 155
[2 TEU TVE TEES REARS Te Ceri SAE ter toni ck ra Ces at Cec Ae RCo nS 150

Si raVahe Mahan neces eire, ete, ursleta ec sl ole icy Ath Super Ae CIES EA Ni EO TR a nd 156
Crowseandwblackinind sma erenas Secs n sie iaes scat teins Sectaeriatetis.e © he ues s siete 156
thes Commone Grubs Waspr (L4epiia ise ae ye ances seta Sere area ake eres ois ste 157
Miscellancouse Insect nemiés. «0... 2 .eda ies e ctl. ook Fe een ice aaa 160
NC GRO PILTIDLI GR CAS TMIVCEGS 2h cries sch a ade cyan asc vabaL era la coetat cba fc eT EIN hale 160
SURE rea ORC OLAUINP. © peers. chad 3 Stole tad ocd d SI a ad es ain, STR Neate aI a pve es 161
SAIN ALI MUST MCLEIALS 5.18: Sion. Ato oe cle Pte ala Mh oR LEME Se aaa aad ee 161
JEN ER I! UCI CRAG eo cosa tes ane ha Ren ey ieee ia Be ara Sra Eee tee TIN Re 162
Dla PULA Shots Me WVASILCS AS aif as Retyee oat thera a a hee Wate Ae Ne eats 163
INeinOnsetouSoleanelS ubsotle eyes cr as nore kts sore cise eae se hist 164
Relations. to Aeneultiraln Managements: taste te char aseelut sie cl eles wie chee 165
eRe teihe sig FOC POG sth aac are x .ecbcla yk drt aN a aA Aa INS Eee aS eine ee 165
JEST EarCepohoroyal “ewok ann] Rees po YeKd bien men a earn Mer ec ete uate 2 ere Pe A ne eee eee 166

Note.—The articles of this report have all been previously
printed in the Bulletin of the Agricultural Experiment Station with
the exception of that on the elm twig-girdler, on pages 118-134,
which is now published for the first time. Plates IX., X., and XI.
of this report are also here first printed, the others having been
already once used in the experiment station articles, except Plate
VIII. and the frontispiece, which were printed in illustration of
Article I of Volume VII. of the Bulletin of the Illinois State Lab-
oratory of Natural History.

INJURY TO CORN BY THE TIMOTHY BILL-BUGS
(SPHENOPHORUS SP.).

In a general article on “The Corn Bill-bugs in Illinois,” pub-
lished in my Eleventh Report as State Entomologist (pages I-26), a
brief account was given of observations made in fields near Roe
ville, Christian county, in 1902 (page 7); but the data in my pos-
session concerning injuries to corn at this place and their relation
to previous crops and to the history of the land, were not fully util-
ized in that paper. Our observations and correspondence have made
it evident for some time that bill-bug injury to corn is imperfectly
appreciated by corn growers and but little understood by them, and
it consequently seems desirable that the careful work done on this
insect injury near Taylorville should now be fully reported and thor-
oughly discussed.

June 26, 1902, Mr. D. S. Dalbey, a senior agricultural student in
the University of Illinois, sent me the following note :—

“T have received from my father, Wm. M. Dalbey, of Taylorville, Illinois,
some specimens of corn plants affected by the corn bill-bug. The land on which
the infested corn was grown is timothy sod plowed in April of.this year, and is
located two miles northeast of Taylorville, on my father’s farm. The damaged
area covers forty acres, and the extent of the damage involves about half the
stand. The plants affected are not dead, but have a sickly yellow color, and the
leaves are punctured with holes.”

I further learned that this land had been in timothy for the four
years preceding, and the year before that in wheat. Clover and
timothy had been originally sown together, but the clover ran out
and the crop was practically pure timothy by 19ot.

EXAMINATION OF INJURED FIELD.

June 30, 1902, I sent Mr. E. S. G. Titus to Taylorville with in-
structions to make a careful study of the condition of the infested
field and to collect information for a comparison of its agricultural
history with that of other fields of corn in its neighborhood, the ob-
ject being to ascertain the full effect of bill-bug injury to corn on up- ©
lands, and to discover any differences in respect to this injury due
to differences of agricultural management.

This work was done by Mr. Titus with characteristic thorough-
ness, intelligence, and skill. On his first visit, made June 30, he
platted the Dalbey field, selecting and marking 650 hills which had
been more or less injured by corn bill-bugs. On another visit, August
Io and 11, he made notes on the condition of these hills, and

9
“

October 2 and 3 he carefully examined them with reference to the
condition of the stalks and the number and quality of the ears, in
comparison with like facts concerning uninjured hills in the same
field. Observations were also made on the condition of fields of
corn on other farms of the neighborhood. The data thus obtained
have since been summarized and tabulated for comparative study,
and the materials are thus in hand for a fuller study of Sphenoph-
orus injury to this crop than has ever before been reported.

DISTRIBUTION OF INJURY.

The injury to the corn in the Dalbey field was very uneven. In
one corner almost every stalk on several acres had been damaged,
while in other parts from 25 to 50 per cent. of the plants had been
attacked. The distribution of the injury seemed not affected by the
lay of the land or the moisture in the soil, there being more injury
on low moist ground at one side of the field and less on similar
ground at the other side than there was on the higher and drier
ground.

Tue INJURIOUS SPECIES.

The species of Sphenophorus actually responsible for this mis-
chief was not definitely ascertained, the beetles having all disap-
peared from the field; but as the larva of Sphenophorus parvulus
was common in the bulbous roots of timothy on adjacent prem-
ises, and as the old timothy bulbs still present in the injured
corn field had been similarly hollowed out by bill-bug larvee the year
before, the probability is strong that this species was largely con-
cerned in the injury under observation.

Tue Injury To TIMoTHy.

Fields of timothy near by, which had been in that crop for three
or four years in succession, had at this time from 50 to 75 per cent.
of the bulbs more or less injured and infested, many of them con-
taining larve ranging in size from those evidently but just hatched
to those large enough to fill the whole timothy bulb. In fields but
two years in timothy, on the other hand, from 10 to 20 per cent. of
the bulbs were infested. The injured plants were inclined to throw
out suckers at the base and also at the first joint above the ground.
Where the bill-bug larva had eaten out all the substance of the bulb,
it had often drilled into an adjacent bulb, and was found feeding
therein. Some larve were seen just cutting their way out of the
first bulb, and others in the act of boring into the second, a part of

3

the body in each. The effect of this amount of infestation on the
timothy crop itself must certainly have been considerable, and the
conditions were, of course, unusually dangerous to the corn crop fol-
lowing.

Tue Injury To Corn.

The injury to corn had resulted variously, the differences being
probably due to the age of the plant when injured, and to the num-
ber of punctures made in a single stalk. In many cases, as will be

_. presently shown, the stalk had been killed, doubtless when the plant

| was still quite young. In other cases the stalk, though nearly or
‘quite full grown, had fallen to the ground in consequence of a de-
ficient root development, brace-roots being indeed practically lack-
ing. Injured stalks were also smaller than normal just above the
ground and at the joints higher up, and were likely to lean from the
base or to bend at the weakened joints. A considerable percentage
of the stalks in hills which had been infested had never formed the
ear (at least 33 per cent. of these stalks being barren, as against 4
per cent. in uninfested hills), and on a much larger percentage of
them the ear was either a small nubbin or imperfectly filled out. It
was the owner’s opinion that the worst-infested parts of the field
averaged about twenty bushels of corn to the acre, and that the part
not infested yielded from forty-five to fifty-five bushels.*

*A letter received from Mr. H. Ll. Jones, of Geneva, I1l., since this manuscript was pre-
pared, makes mention of an effect of bill-bug infestation which has not previously been noticed,
and describes also his method of diminishing the damage. Hesays: “I hada rather expen-
sive experience with bill-bugs last season on a pasture plowed in spring. They appeared when
the corn was four to six inches high, and crippled it badly in spots sothat the injured inner
leaf would break over and curl up, thereby preventing the next inner leaf from coming out
and thus dwarfing the stalk. I immediately put men and boys into the field, who replanted
the destroyed hills and picked the curled tops from all the damaged stalks, in this way saving
nearly allthe crop. Thiscorn husked seventy bushels per acre where I am sure that it would
have yielded eighty bushels but for the damage sustained. If the curled leaves had not been
picked from the tops of the plants, I think that the crop would not have been more than fifty
bushels. ‘The labor cost about $5.00 for twelve acres, and it might help some other man to
know my experience in saving part of a crop.”

GENERAL RESULTS OF THE INJURY.

As affecting the whole Plant.—For a precise comparison of the
condition of uninjured corn with that of corn attacked by the bill-
bugs, 328 hills were carefully selected as representing the average
condition of infested and uninfested hills in this field. One hun-.
dred and sixty-four of these were free from injury, and each of
the remaining 164 contained injured stalks. There were, in all, 363
stalks in the uninjured hills and 313 in the injured hills,—a differ-
ence indicating that 50 stalks, or 14 per cent. of the whole, had been
killed by the bill-bugs. In the uninjured hills 306 stalks were stand-
ing erect, 29 were leaning, and 28 had fallen to the ground. In the
injured hills 64 stalks were standing, 99 were leaning, and 150 had

4

fallen. That is, 33 per cent. of the number of the stalks which
should have been erect in the injured hills had been made to fall, and
Ig per cent. of them had been weakened sufficiently to cause them to
lean or bend. More generally speaking, 67 per cent. of the stalks—
that is, 242 out of 363—had been either killed or noticeably injured
in the infested hills.

The ratio of damage to the plant as a whole may be more simply
and forcibly shown by saying that in the uninjured hills there were
306 stalks erect and in good condition, while in the injured hills
there were but 64 such stalks. In other words, the bill-bugs had
killed or palpably damaged 79 per cent. of the stalks in the infested
hills which would have continued in good condition except for this ©
insect attack.

As affecting the Ears——Comparing the two lots with reference to
the number and condition of the cars borne by them respectively, we
find that the uninjured hills bore 349 ears of all kinds, and the in-
jured hills 211,—a loss of 138 ears, or 40 per cent. of the whole. Of
the uninjured corn 282 of the ears were graded as good, 44 as fair,
14 as poor, and 9 as nubbins, while the injured corn bore 24 good
ears, 75 fair ears, 72 poor ones, and 40 nubbins.* (See Fig. 1.)
Otherwise stated, besides the 40 per cent. of the ears which had been
sacrificed to the bill-bugs, 9 per cent. had been considerably injured
and 26 per cent. had been badly injured as a result of bill-bug at-
tack. Not less than 75 per cent. of the ears in these hills were thus
either lost or seriously injured.

The loss in number and condition of the ears borne by infested
hills may perhaps be more clearly illustrated by the statement that
282 good ears were borne by the uninjured hills and only 24 by the
injured,—a loss and injury combined amounting to 81 per cent.

It further appears from the data in hand that the uninjured hills
bore 96 ears per hundred stalks, and the injured hills 67 ears per
hundred,—a loss of thirty per cent. in number of ears per hundred
stalks,—and that the uninjured corn yielded an average of 200 good
or fair ears per hundred hills, and the injured corn 73 such ears per
hundred hills,—a loss of 61 per cent. in number of fairly good ears.

Tota, Amount oF INJuRY.

The above ratios do not hold, of course, for the entire field, but
only for the part injured, and for an understanding of the condition
of the field in general an estimate of the percentage of injured hills
is necessary. Six hundred and eighty-two hills were examined for

*“Wair ears” were of medium size and imperfectly filled, “poor ears’? were short and
pony filled, and nubbins were short, small, and not filled to the tip, and were otherwise de-
ormed, with poor and injured grain.

5

this purpose, and 199, or 29 per cent., were found injured; from
which we learn by a simple computation that approximately 12 per
cent. of the ears which the entire field should have yielded were lost
in consequence of bill-bug injury, and that 7 per cent. were badly
injured and 3 per cent. considerably so.

Dee ie Ta py 7
vageovoeogsgnean eodoneee
ueseoane080ot0ER O99

vapessonsssne ona: 4 Atp

Pertinent.

Fig.1. Sample Ears from Dalbey field; “good,” ‘“‘fair,” and “poor” grades of this paper.

Samples of uninjured ears and of those called badly injured,
brought in by Mr. Titus, indicate that the yield from “‘fair ears,”
“poor ears,’ and nubbins would not be more than one third of that
from an equal number of ears of the uninjured corn. It is proper to
add, consequently, to the 12 per cent. of total loss some two thirds
of the 10 per cent. of injured ears, making another 6 per cent. of
loss, or a total of 18 per cent. for the entire field.

This conclusion is substantially supported by the owner’s esti-
mate of twenty bushels per acre for the infested area and fifty
bushels for the uninfested; since, by using the above-mentioned
ratio of 29 per cent. for the number of hills injured, we find that the
average yield would be 41.3 bushels per acre, a quantity loss of 8.7
bushels per acre because of bill-bug injury, or 17 per cent. of the
normal yield. No account is taken in this estimate of the deteriora-
tion in quality of the injured corn, which, if included, would increase
the loss materially. As the season was a favorable one for corn, and
as the variety used (Reid’s Yellow Dent) was reported to have
hardened much earlier than other varieties planted at the same time,
this loss is probably under rather than over the general average un-

6

der similar conditions of injury. The following table will serve to
exhibit these data and conclusions in more compact form.

STaTisTics OF Biri-Buc Injury To Corn, DaLBEy FIELD, 1902.

Uninjured hills Injured hills Losses from injury
No. Per cent, No. Per cent. No. Per cent.

Number of hills..| 164 164

Number of stalks! 363 3138 86 50 14
Fallen stalks....| 28 8 150 48 122 33
Leaning stalks..| 29 8 99 27 70 19
Mrect stalks... 306 64 21 242 719
Number of ears. .| 349 211 60 1388 40
INMbbInNS= 2 eis 9 3 40 12 a3 9
POOMEALS See eee 14 4 72 pal 58 17
Maimears: | ayaa. 44 13 75 22 31 8)
Good ears.: ..... 282 24 9 258 81

METHODS OF PREVENTION.

The contrast observed between corn grown on timothy sod and
plowed early in fall, and the Dalbey field, which was plowed only a
few days before planting, was discussed in my Eleventh Report.
No trace of bill-bug injury was detected on the fall-plowed land, al-
though dead timothy bulbs still in the ground showed distinctly
that they had been hollowed out by bill-bug larvee. The inference is
thus strongly suggested that early fall-plowing of timothy previous
to corn planting will protect the corn from injury. A similar state-
ment was made in 1892 by Osborn and Gossard, who say that since
worse injuries are likely to occur on land in grass the preceding year
or adjacent to such land, plowing should be done as early in the pre-
vious season as possible; and that since bill-bug injury is mainly
done early, infested ground should be planted as late as practicable.*

John B. Smith, the State Entomologist of New Jersey, advised,
in the same year, plowing of sod for corn in fall and early winter,
with a view to killing out the bill-bug larve living in or under the
sod; and in the following year he says that this injury has been
minimized where fall plowing has been practiced. +

I’. M. Webster also surmises }{ that fall plowing would probably
result in the diminution or prevention of the injury, and suggests
planting some other crop than corn where the occurrence of this in-
jury is very probable; and H. E. Weed says in 1895 § that where

*Bull, 18, la. Agr. Exper. Station, pp. 507-509.

+Twelfth and Thirteenth Ann. Reports, N. J. Agr. Exper. Station, for the years 1891 (pp.
394, 395) and 1892 (p. 390).

t‘*Ohio Farmer,” July 20, 1893, p. 57.

§Bull. 35, Miss. Agr. Exper. ation, p. 154.

_
(

sod has been broken up in fall the bill-bugs will do but little damage
the following spring, and that the second planting, whenever the
time of plowing, will be little if at all attacked.

Early fall-plowing of grass-lands would consequently seem, in
the present state of our knowledge, to diminish greatly, if not com-
pletely to prevent, injury to corn by bill-bugs the following year; a
statement which must be applied to blue-grass pastures as well as
to timothy meadows, since the bill-bug most abundant in timothy,
Sphenophorus parvulus, has also been found destructive in blue-
grass lawns. (See Bull. 22, U. S. Dept. Agr., Div. Ent., p. 99.)

As a check to injury to timothy meadows I see nothing better
than to avoid keeping the same ground in timothy for more than two
years ata time Where the pest becomes so common and destructive
as in the Dalbey neighborhood, it would seem wise to substitute
clover for timothy, so far as practicable, for a considerable term of
years.

SUMMARY.

In a forty-acre field of corn in Christian county, injury by bill-
bugs was found to have affected about 29 per cent. of the hills, di-
minishing the number of stalks in such hills by 14 per cent. and the
number of ears by 40 per cent., and seriously injuring 26 per cent.
more of the ears. It also caused about a third of the stalks in the
injured hills to fall to the ground, and weakened about a fifth of
them additional. The total loss in the field was estimated at 18 per
cent. of the crop, or nearly nine bushels to the acre.

Comparison of this with other fields shows that the injury was
due to planting corn after timothy plowed in spring, and that
most of it could have beer prevented by early fall-plowing of the
timothy sod.

FIELD EXPERIMENTS ON THE CORN ROOT-APHIS .-
(APHIS MAIDIRADICTS FORBES):

The corn root-aphis, wintering as an egg in the nests of ants in
corn fields, begins to hatch, according to our observations in central
Illinois, about April 8, and may continue this process for as much as
six weeks, or until the latter part of May.* The earliest individuals
of this first generation get their growth in approximately twenty
days, and then give origin at once to representatives of the second
generation, which in eighteen or nineteen days may themselves be-
gin to reproduce. The growing period for an individual of the third
generation is approximately eleven days, making a total of not far
from fifty days for the entire life of a series of the first born of the
first three generations from the egg. ‘That is, by the last of May
the latest to hatch of the first generation would coexist in the fields
with the earliest born of the third generation. All hatching from
the egg are wingless females, but a small, and no doubt variable,
percentage of the second and third generations are winged, and
leave their underground quarters to fly abroad and start new col-
onies elsewhere. The later steps of this life history are not neces-
sary to a discussion of the experiments here reported.

In view of the fact that the young lice are dependent upon their
attendant ants, at least until they have been placed upon the roots of
plants suitable for their maintenance, it has seemed to me prob-
able that an early and repeated stirring of the ground infested by
these insects in early spring, scattering the eggs and young aphids
again and again through the dirt, and killing the young weeds in the
corn field upon which they must at first depend for food, would
have the effect to destroy great numbers of them and thus to weaken
the force of the aphis attack upon the young corn at a time when it
is most susceptible to injury.

THE SEASON OF 1904.

With a view to testing this supposition, a field experiment was
arranged in the spring of 1904, to be made in two neighborhoods
notorious for some years for an abundance of the root-aphis on
corn and a considerable injury to the crop in consequence. Circum-
stances beyond my control prevented, last year, as early a beginning
as might have been desirable, and nothing was done in the experi-

*We have this year collected eggs uf the corn root-aphis from ants’ nests in the field May
19. ‘These eggs hatched under our observation, and the young were maintained on corn, but
were not kept until mature.

a

mental fields until May 13 in one locality, and May 23 in the other.
I owe the opportunity to undertake the investigation at this time to
Dr. J. W. Folsom, Instructor in Entomology at the University of
Illinois, who was good enough to undertake the field inspections
for me, and upon the report of whose observations the following
statement of results is based.

The season was at least a fortnight later than usual, and it is
consequently difficult to say just what generations of the aphis were
in existence at the time. Judging, however, by the calendar for the
three earliest generations given above, and by the field and insectary
work of 1905, reported farther on, it seems likely that the first and
second generations were abundant in the fields, and that the third
had not yet begun to appear. That the second was present is un-
questionable, since occasional winged individuals-»were found.

The Galesburg Cultivation Experiment. (Table I.).—In the
first experiment, made on the farm of Mr. J. H. Coolidge, about
three miles from Galesburg, in Knox county, Ill., two parts of a
large field of corn were used, one of which (Plat A) received the
usual treatment in preparation for planting and the ordinary culti-
vation afterwards, while in the other, the experimental plat (Plat,
B), the ground was repeatedly disked and harrowed between plow-
ing and planting, and harrowed and cultivated promptly thereafter.*
In this experimental plat were thirty-two rows, each eighty rods
long, and in the check plat ninety rows of the same length. ‘The
latter was plowed early in May, planted May 13 to 17, harrowed
once thereafter, and cultivated June 9, the condition of the corn with
reference to ants and root-lice being there determined on the t1oth
of June. The thirty-two experimental rows were plowed May 14
to 16, the ground was thoroughly disked three times on the 18th,
21st, and 25th of May, also harrowed May 25, and planted on this
same day. It was cultivated May 28, harrowed on the 30th, and
inspected June Io.

It will be noticed as an important difference between these two
fields that the experimental plat was planted ten days later than the

*The various operations on the ground used in these experiments were as follows:—

First, plowing with an ordinary mold-board plow; second, harrowisg with a toothed
harrow; third, disking with a disk harrow; tourth, spading with a so-called spading harrow;
fifth, pulverizing with a so-called “‘Acme”’ harrow, sometimes known and soldas a “‘pulverizer;””
sixth, rolling with anordinary smooth roller; seventh, cultivating with anordinary “sulky”
cultivator with shovels. These terms are used as above defined throughout this paper in
both tables and text. The plowing in the experimental plats was from five to seven inches
deep; the toothed harrow stirred the earth, asa rule, toa depth of about two inches; the disk
barrow commonly worked twice as deep or more, moving the dirt laterally and mixing it
thoroughly in the process; the spading harrow differed but little from the disk harrow in its
Operation except that it was likely to go deeper, and did not move the earth laterally to so
great a distance; the ‘-Acme”’ harrow, or “‘pulverizer,” consisting of a row of blades set ob-
liquely into an angular beam, followed by a transverse row of cylindrical pointed teeth, worked
toa depth of abont three inches, asa rule,stirring and pulverizing the ground more effectually
can the common toothed harrow, but not to the depth of the disks or moving it laterally as

ar.

10

check. This was due to rainy weather, which interrupted the plant-
ing; but as sixteen days elapsed between the planting and the in-
spection, there was doubtless ample opportunity for the transfer of
all living root-lice from the weeds to the corn,—a conclusion to
which I think no one will take exception who has been accustomed to
observe the corn-field ant in charge of the corn root-aphis.

Additional to this, the difference in the treatment of the plats
was the disking of the experimental plat three times and its harrow-
ing once, and the differences between these plats with respect to ants
and root-lice are to be taken as due to this additional and repeated
stirring of the soil of the experimental plat. *

June 10, two hundred and twenty-five hills, distributed over five
different rows of the experimental (B) plat, were carefully exam-
ined by Dr. Folsom by digging up the corn and counting the ants.
and root-lice found upon the roots and in the hills. The rows
chosen for these counts were taken from various parts of the field,
being respectively the first, seventh, ninth, twentieth, and thirty-
second of the entire plat. The last, it will be noticed, was the row
next adjacent to the check plat. In the latter plat (A) seventy-five
hills were similarly examined from the first, second, and ninetieth
rows.

For convenience in comparison, the numbers given will be those
for a hundred hills of corn taken as a unit. It thus appears (see
Table I.) that twenty-eight per cent. of the hills of the check plat
(A) were infested with ants, and that on the experimental plat
ten per cent. of the hills were so infested; that seventeen per cent.
of the check hills were infested by root-lice, and three per cent. of
the experimental hills; that one hundred of the check hills contained
2263 ants, and one hundred of the experimental hills, 185 ants; that
one hundred of the check hills contained 858 root-lice, and one hun-
dred of the experimental hills, 79 root-lice. Or, more briefly stated,
the untreated or check part of this field contained in equal areas,
about twelve times as many ants and three times as many hills in-
fested by them, and about eleven times as many root-lice and six
times as many hills infested by them, as did the treated or experi-
mental plat.

it

TABLE I. ABSTRACT OF COOLIDGE EXPERIMENT, 1904.

(Planted May 13-17 and May 25; examined June 10.)

Plat A Plat B
*Plowed (1), harrowed (2), *Plowed (1), disked three
cultivated (9) times (3, 4,5), harrowed (6),
cultivated (7), harrowed (8)
75 hills examined 225 hills examined
Per cent. Number of Per cent. Number of ©
of insects per of insects per
hills infested hundred hills hills infested hundred hills
Amitav 28 2263 10 185
Aphids..... 17 858 3 79

1. Plowed May 14 to 16. 2. Harrowed May 17. 3. Disked May 18. 4. Disked May 21.
5. Disked May 25. 6. Harrowed May 25. 7, Cultivated May 28. 8. Harrowed May 30.
9. Cultivated June 9.

The Harvel Experiment. (Table II.).—In the second experi-
ment, made on the farm of Mr. A. T. Doerr, near Harvel, in Chris-
tian county, a field of nine acres was divided into two parts, an
experimental plat of three acres (Plat B) and a check plat (A}
of six acres. In this field also the experimental plat consisted of
thirty-two rows eighty rods in length.

The check plat (A) received no treatment until June 1, when
it was spaded and harrowed. It was planted June 2 and haere
June 13, the inspection being made the following day. On the
experimental plat the stalks were harrowed down, raked, and burned
May 13, the ground was plowed May 23, harrowed May 25,
“spaded” on the 26th, and harrowed again on the 28th. At this
time the field was practically free from weeds. On the 29th it
rained all day, the first rain since the ground was plowed. ‘This plat
was spaded and harrowed June 1 and 2, and planted on the latter
day. Rain followed on the 3d day of June, and the weather was wet
until the 9th. The plat was rolled and harrowed on the 11th and
cross-harrowed on the 13th, the inspection following the next day.
In this case it will be noticed that the whole field was planted at the
same time.

The harrowing to break down the stalks could scarcely have dis-
turbed the ground sufficiently to interfere with the operations of
the ants, and in a comparison of the plats that item may best be
omitted. The difference in treatment is thus reduced to once plowing,
once spading, harrowing three times, and rolling once, and to this

*Figures in parentheses refer to dates given at bottom of table.

12

the difference of the two plats with reference to ants and root-lice
can fairly be attributed.

For a comparison of these plats seventy- -five hills of corn were
dug up in the check plat and one hundred in the experimental plat.
Reducing the numbers given, for convenience of comparison, to a
unit of one hundred hills, it appears (Table II.) that sixty-two per
cent. of the hills were infested with ants on the check plat, and
twenty-five per cent. on the experimental plat; that forty-four per
cent. of the check hills were infested by root-lice, and eleven per cent.
of the’ experimental hills; that one hundred of the check hills con-
tained 1961 ants, and one hundred of the experimental hills, 630
ants; that one hundred of the check hills contained 1464 root-lice,
and one hundred of the experimental hills, 198 root-lice. Or, more
briefly and generally stated, and comparing equal areas of the two
plats, we see that the check plat contained approximately three
times as many ants infesting two and a half times as many hills, and
seven times as many root-lice infesting four times as many hills as
did the experimental plat.

The difference in apparent effect of treatment between the Gales-
burg field and the Harvel field may have been due to the fact that the
Harvel field was much worse infested than the other. Twenty-eight
per cent. of the hills were infested with ants at Galesburg and sixty-
two per cent. at Harvel; and seventeen per cent. of the hills were
infested with root-lice at Galesburg and forty-four per cent. at Har-
vel, with a difference of only four days in the dates of inspection.

Where both ants and root-lice are numerous, the chances that
some of the former will find some of the latter after both have been
thoroughly scattered through the soil, is doubtless greater than where
both ants and root-lice are relatively few. Of course, as fast as root-
lice or their eggs are recovered by the ants, whether originally the
property of the ants or not, they will be appropriated and established
on the plants in the field. Furthermore, later observations reported
in this paper, have made it probable that ants actively convey their
charges from one part to another of the field as conditions become
less favorable where they were established. It is likely, consequently,
that in a crowded field the root-lice would be carried over to plants
lightly infested on the experimental plat, and that the normal re-
sults of the treatment would be thus to some extent masked or lost.

It is at any rate made certain by our later observations that as
the food plant becomes crowded, much larger percentages of winged
lice appear, and these, by emerging from the ground and scattering
abroad, tend to diminish the ratio of increase in the over-infested
field and to increase it elsewhere. Such a migration of winged lice

13

would still further diminish and mask the effect of the treatment.
In other words, if an entire field is treated, the benefit will be greater
than where only an experimental plat is used, and the results of
treatment here given are less than they should be if they are cor-
rectly to indicate the probable effect of the procedure used.

It should be noticed further that the treatment of the Coolidge
and the Doerr fields was different especially in the fact that the lat-
ter was harrowed three times while the Coolidge field was disked
three times. As the harrow tooth does not penetrate the earth to
so great a depth as the disk, and does not move the dirt so far or
mix it so well, much of the difference in result is probably attribu-
table to this difference of implements.

TABLE II. ABSTRACT OF DOERR EXPERIMENT, 1904.

(Planted June 2; examined June 1/4.)

PlatA Plat B.
*Spaded (5), *Plowed (1), harrowed (2),
harrowed twice (6, 9) spaded (3), harrowed (4),
spaded (5), harrowed (5),
rolled (7), harrowed
twice (8, 9)
75 hills examined 100 hills examined
Per cent. Number of IPerm cent. Number of
of insects per of insects per
hills infested hundred hills hills infested hundred hills
PANSTUNG Slegetetosral 62 1961 25 630
Apbhids..... 44 1464 TU 198

1. Plowed May 23. 2. Harrowed May 25. 8. Spaded (with spading harrow) May 26.
4. Harrowed May 28. 5. Spaded June l. 6. HarrowedJune2. 7. Rolled June ll. 8 Har-
rowed June ll. 9. Harrowed June 13.

THE SEASON OF 1905. BRADFORD, ILLINOIS.

For a further test of agricultural measures against the corn root-
aphis, I planned and provided for a field operation to begin as early
as practicable in the spring of 1905, in a neighborhood in Stark
county to which my attention had been especially called by the fol-
lowing letter of March 11 from Messrs, Deyo and Foster, real estate
agents at Bradford, III.

“The farmers here are troubled with lice on the roots of the
corn. Even on good ground we find that the roots are alive with
them and the corn makes a very poor growth until about harvest-
time. If we have rains it makes a fair yield, but blows over very

*See note to Table 1., p.105.

‘i 14

easily. Will you please tell me what you know in regard to the
matter, and what has been done on this subject.”

Two assistants of the office, Mr. E. P. Taylor and Mr. E. O. G.
Kelly, visited this neighborhood April 6 to 13, and after a careful
survey of a large number of farms, selected three for special experi-
ments, belonging respectively to H. B. Hinman, Edward Finne-
gan, and Frank Barto. Special observations were also made on the
underground aphids in fields of corn and oats in comparison, on the
farm of the F. H. Thompson Estate.

At the time of this first visit the root aphids were all still in the
egg stage in the burrows of the small brown ant (Lasius niger
alienus). ‘The ants themselves were opening and extending their
burrows, and the aphid eggs were found in clusters in carefully
formed chambers about an inch under ground, in varying numbers,
the maximum observed in a single nest being two hundred and
seventy-five. ‘The ants themselves had gone as deep as seven and a
half inches, but no aphis eggs were found deeper than an inch. ‘The
fields were dry, and plowing had already begun. The soil was weil
pulverized, and many ants’ nests had been turned over and covered
up, but were not much broken up or scattered by the plow.

The first aphis egg hatched April 9, and several others from
the same lot hatched the following day. ‘The young as fast as they
left the egg were placed by the ants on the roots of smartweed
plants. Many of these weeds were from half an inch to an inch
high, but many, barely sprouted and not yet out of the ground, had
been found by the ants, and exposed by burrowing along them. The
field work at this place was assigned to Mr. E.. O. G. Kelly, who de-
voted his entire time to it for several weeks.

The weather of April and May was so unusually wet as to in-
terfere materially with the intended treatment of the experimental
plats. It also prevented as frequent access to the fields as was de-
sirable for purposes of inspection, the exact comparison of check
and experimental plats being indeed delayed until May 31, so long
a time after treatment in some cases as to impair greatly the values
of these comparisons. Illustrations of this point will be given in
some detail in the general discussion at the conclusion of this paper.
No precise record was kept of the rainfall, but the following memo-
randa will be of assistance in discussing the experiments.

A light rain fell April 6, but from the 1oth to the 25th—the
period of plowing—the weather was, on the whole, quite dry. April
27 and 28 heavy rains fell, but the fields were fairly dry again from
April 30 to May 8. From the’gth to the 12th it rained hard and
frequently, and the soil was continuously wet to the 15th, when it

15

rained heavily again, and daily thereafter to the 20th. Rains fell
again on the 29th and 3oth, and on the 4th of June.

The Hinman Experiment. (Table III.).—On the farm of Mr.
Hinman, four and a half. miles east of Bradford, was a field of
seventy acres of corn, forty acres of which was selected for a field
experiment. This had been planted to corn each year since 1902,
and injury by the root-aphis on the higher parts of the field had
been noticed in 1904.

This forty was divided, for the purposes of the experiment, into
three strips. One plat*(A) received the usual preparation of the
land for corn. The stalks of the old corn were cut, and the ground
was plowed from April 7 to 28, harrowed the first time May 3 and
4, pulverized with a disk harrow on May 5, and harrowed again
May 8. Plat C was reserved for an experiment with minimum
cultivation. The stalks were cut, and the ground was plowed April
7 to 28, like the preceding, and harrowed May 3 and 4 and again
May 8. Plat B was set aside for an experiment with the effects
of maximum cultivation, but repeated rains greatly hindered the
farmer’s work, and finally, as a consequence, this field was plowed
like the others April 7 to 28, after the cutting of the stalks, was har-
rowed May 3 and 4, disked May 5 and again May 8, and har-
rowed also on the latter date. The preparation of these three plats
thus varied as follows :—

Plat C (minimum cultivation) differed from plat A, the check,
only in the fact that the ground was not disked. Plat B (maximum),
on the other hand, differed from the check only in the fact that it was
disked a second time. B thus differed from C by two additional
treatments with, the disk harrow. It will be noticed that all the plats
were treated alike until May 5, when the ground of two of the plats
was first disked, and that A and B received identical treatment until
May 8, when the latter was disked a second time.

The entire field was planted on three different dates, the planted
rows running crosswise of the plats. ‘The first hundred rows on the
north end of each plat were planted May 8, and, rains intervening,
one hundred and sixty-four rows next south of these were planted
May 13 and 15. Rains again followed, so packing the soil that the
remainder of the field—one hundred and eight rows—was harrowed
again (with an Acme harrow, sometimes called a pulverizer) and
planted on the 22d and 23d of May. This last-planted section thus
constituted a distinct division of the three foregoing plats, receiving
one additional treatment with the Acme harrow, and being planted
two weeks later than the first planting of a hundred rows and about
a week later than the second planting of one hundred and sixty-four

16

rows. ‘The extremes of treatment in this field, it will be seen, were
between the part of plat C first planted and the part of plat B
planted last, these two plats differing in the fact that the late-
planted part of plat B was harrowed twice more (once with Acme
and once with toothed harrow) and disked once more than the
early-planted part of C.

Observations were made in the Hinman field by Mr. Kelly, at as
frequent intervals as the weather permitted, during the period from
May 2 until the planting was finished on the 23d. On May 2, where
the ground had been merely plowed many young root-lice were seen
in the field, which the ants were placing on young smartweeds. Five
ants’ nests, all within a space twenty feet square, were explored and
found to contain from thirty to one hundred and thirty-five ants,
from twenty to forty aphis eggs—green and about to hatch—and
from thirty-five to eighty-six young root-lice, all of the first genera-
tion from the egg. The harrowing of the whole field May 3 and
4 stirred the weeds about and disturbed the ants and aphids, but
Seemed to kill neither insects nor weeds. The disk harrow or pul-
verizer loosened the soil to the full depth of the plowing, and scat-
tered the ants and aphids greatly. On the 6th of May ants were
everywhere on and through the soil, and an occasional aphis was
seen on roots of grass or smartweed, seldom, however, with any ants
in company. May 13, the ants were generally reestablished in the
plowed part of the field, and many root-lice were collected from their
burrows feeding on foxtail-grass and on an occasional volunteer
plant of corn. Thirty-two ants’ nests were dug out on this date,
each containing from six to one hundred ants. In seventeen nests
there were no root-lice, and in the remaining fifteen these varied in
number from two to sixty-five. ‘There were, on an average, twenty
aphids to each nest containing them, all wingless, but many already
full grown, and all apparently of the first generation from the egg.
May 18, the corn planted May 8 was beginning to come up, and
twenty-five hills were dug out. Ants were found in two; root-lice
in none.

May 31, a test examination of this field was made by digging up
in the earliest-planted portions of plats A, B, and C, fifty hills
from each, and in the later-planted portions twenty-five hills from
each plat. Although the number of hills dug up was perhaps too
small to give satisfactory averages applicable to the entire field,
Mr. Kelly tells me that the several lots were not taken entirely at
random, but that each was carefully chosen with the idea of making
it a fair and sufficient sample of its plat. In digging up the plants
the whole root system was exposed, and all the ants and all the root-

ne
lice were collected and counted for'each hill. For convenience in
comparison the data will be given in each instance for a hundred
hills of corn taken as a unit. Those for the early and late plantings
will be given separately—first those for the parts of the field which
received the least treatment, and then, by successive steps, for those

which were treated most. (See Table III.)

TABLE III.

ABSTRACT OF HINMAN EXPERIMENT, 1905.

(Planted May 8, and May 13 to 15; examined May 31.)

Pjat A, 1 Plat B. 1 - Plat C, 1
*Plowed (1). harrowed | Plowed (1). harrowed | Plowed (1), harrowed
(2), disked (3), har- (2), disked twice twice (2, 4)

rowed (4) (8, 5), harrowed (4)
50 hills examined 50 hills examined 50 hills examined
Percent. | Number Per cent. | Number Percent. | Number
of of insects of of insects of of insects
hills per hun- hills per hun- hllis per bun-
infested |dred hills| infested | dred hills] infested |dred hills
PANES eee enol» 54 2012 26 744 64 2096
Aphids........ 40 838 12 158 48 974
A,2. Pulverized (6) B, 2. Pulverized (6) C,2. Pulverized (6)
25 hills examined 25 hills examined 25 hills exarhined
PRTN Siete ceva, 24 260 ¥2 66 24 194
Aphids........ 12 62 0 0 20 146

1. Plowed April 7 to 28.

2. Harrowed May 3 and 4.

3. Disked May 5.

4, Harrowed

May 8. 5. Disked May 8, 6. Pulverized (Acme harrow) May 22 and 23.

In plat C, with minimum treatment, sixty-four per cent. of
the hills were infested with ants; in plat A, with medium treatment,
fifty-four per cent. were so infested; and in plat B, with maxi-
mum treatment, the percentage of infestation by ants was twenty-
six. Forty-eight per cent. of the hills of plat C were infested by
root-lice; forty per cent. in plat A; and twelve per cent. in plat B.
One hundred hills in plat C contained 2096 ants; in A, 2012; and
in B, 744. One hundred hills in C contained 974 root-lice; in
A, 838; and in B, 158. In other words, taking the infestation of
plat C as a basis of comparison, we find that the single additional
disking of plat A reduced the number of sills infested by ants to
eighty-four per cent., and those infested by root-lice to eighty-three

*See note to Table l., p. 105.

18 :
per cent., the number of ants per hundred hills to ninety-five per
cent., and the number of root-lice per hundred hills to eighty-six per
cent. Comparing similarly plat B with plat C, we find that the ef-
fect of disking twice was to reduce the number of hills of corn in-
fested by ants to forty-one per cent., and the number infested by
root-lice to twenty-five per cent., and also to reduce the number of
ants per hundred hills of corn to thirty-five per cent., and the number
of root-lice per hundred hills to sixteen per cent. Still more briefly
stated, the root-louse infestation was reduced approximately fifteen
per cent. by disking once; and seventy-five per cent. as to the num-
ber of hills infested, or eighty-four per cent. as to the number of
root-lice in the field, by disking twice (see experiment 5, Table V.).

A comparison of the early-planted part of section C, in which
fifty hills were examined, with the late-planted part of section B,
in which twenty-five hills were examined, gives a surprising contrast.
It will be remembered that all the latest-planted sections received
an additional pulverizing just before planting,—necessitated, in
the owner’s judgment, by the packing effect of a heavy rain while
the planting of the field was in progress. If this circumstance be
taken into account, then it may be said that a comparison of these
two areas indicates that three times disking—the last time soon after
a heavy packing rain—may reduce the number of hills infested by
ants to nineteen per cent., and the number of ants themselves to three
per cent., and may obliterate the root-lice entirely, since none were
found in the twenty-five hills searched in the late-planted part of
section B.

The effect of a single disking, following closely upon a beating
rain, as shown by counts made in each of the three sections before
and after these events and by averaging the percentages for the
three plats, is as follows: The hills infested by ants were reduced
to forty-three per cent. and the ants themselves to ten per cent. of
the number to be found in those parts of the field which had not
been disked after the rain, while the root-lice were reduced by the
same treatment, to thirty-six per cent. in the number of hills infested
and to eleven per cent. in the number of insects in the field.

A further instructive conclusion may be derived from the obser-
vations of May 31 by comparing the product of fifty badly infested
hills with the remaining 225 dug up on that day. The total number
of root-lice found in the fifty hills was 5254, averaging over 105 per
hill, while the total in the 225 hills was 1068, or an average of five
per hill. If these two collections of root-lice be compared with
reference to the percentage of the adults which have developed
wings, added to the pup, which would acquire them at the next

19

molt, we find that this ratio of winged forms is much greater in the
badly infested hills; that the ratio of winged specimens increases,
in other words, with the crowding of the insects and the conse-
quent pressure on their food supply. In the 225 slightly infested
hills were 225 wingless adults and 54 winged adults and pupe, a
ratio of 21 per cent.; while in the fifty badly infested hills were 227
wingless adults and 349 winged adults and pupe, a ratio of 64 per
cent. of the winged form. ‘That is, the winged insects were three
times as numerous in the crowded colonies as they were in the
smaller ones. It is quite probable that experiment will show that
this increase of the ratio of winged to wingless specimens might be
brought about experimentally by various means which have the effect
to diminish the average food supply. It is to be expected, conse-
quently, that mere drouth, if it goes to the extreme of injuring the
plant infested, may have the effect to break the force of the root-
louse attack by stimulating the development of winged specimens,
which, leaving the earth and flying abroad, would give the infested
plant a chance to rally against injury.

The Finnegan Experiment. (Table IV.).—On the farm of Ed-
ward Finnegan, one and a half miles northeast of Bradford, a field
of eighteen acres was selected for experiment. ‘This field had been
planted to corn in 1904, to oats in 1903, and to corn for the three
preceding years. A considerable injury, apparently due to the corn
root-aphis, had been noticed in it in 1904. ‘Two parts of this field,
which may be called plats A and B, were treated as follows :—

Both were plowed April 18 m 21, disked May 22, harrowed
May 23 and 24, and planted May 2A ditered irom A only
in the fact that it was twice disked in succession May 22, instead of
once only on that date. Plat B was a strip running lengthwise
of the field from north to south, and twenty-two rows wide, begin-
ning on the west side; and plat A comprised the greater part of
the field, extending eighty-eight rows inward from the eastern
border. Smartweed and grass grew two or three inches high by
May 22, heavy rains having by this time packed the soil very closely.
The corn was put in about three inches deep, and began to show
above the surface by May 30, on which date the first root-aphis was
found in a hill of corn infested by Lasius alienus. ‘These fields were
examined June g for a test of the results of the single additional
treatment with the disk harrow in which alone the two plats differed
(see Table IV.). Fifty hills were examined from each plat, with
the general result that in the check plat, A, seventy-five per cent.
of them were infested by ants, and that in the experimntal plat,
B, fifty per cent. of them were so infested. In the check plat, A,

20

seventy-four per cent. of the hills were infested by root-lice, and
forty-four per cent. in the experimental plat. The former con-
tained 3034 ants per hundred hills, and the latter 1746—fifty-seven
per cent. of the first number. The latter, or check plat, also con-
tained 2392 root-lice per hundred hills, and the former, or experi-
mental plat, 1362 root-lice per hundred hills—sixty per cent. of the
number in the first.

More briefly stated, the single treatment with the disk harrow
May 22, following immediately upon an earlier treatment the same
day (see Experiment 4, Table V.), had reduced the infestation by
ants by forty-two per cent. in number of insects and by thirty-three
per cent. in number of hills infested; and had reduced the infesta-
tion by root-lice by forty-three per cent. in number of insects and
by forty-one per cent. in number of hills infested, the result being
tested by a critical examination made sixteen days after the field
was planted. In short, a single disking of the soil had diminished
the infestation by ants and root-lice generally by something over one
third.

TABLEIV. ABSTRACT OF FINNEGAN EXPERIMENT. 1905.
(Planted May 24; examined June 9.)

Plat A Plat B

*Plowed (1), disked (2),

Plowed (1), disked twice (2, 3).
harrowed (4)

harrowed (4)

50 hills examined 50 hills examined

Per cent.

Oo
hills infested

Number of
insects per
hundred hills

Per cent.
c

of
hills infested

Number of
insects per
hundred bills

yr
‘

5

74

3034
2392

dO

44

1746
1362

1. Plowed April 18 to 21. 3. Disked second time May 22.

4. Harrowed May 23 and 24.

2. Disked first time May 22.

Observations on the Barto Farm.—A field of seventy acres,
forty-five in oats and the remainder in corn, on the farm of Mr.
Frank Barto, near Bradford, Il., was selected for observation be-
cause of the extraordinary abundance of ants’ nests containing aphis
eggs to be found in various parts of it, and because of the history of
the oats fields with reference to corn preceding, and of one of the
corn fields with reference to oats. It was the principal object of the
observations here made, to ascertain the effect on the corn root-aphis
of a change of crop from corn to oats.

*See note to Table I., p. 105.

21

For the purposes of this discussion the field may be divided into
two parts: one of twenty acres of corn which had been in that crop
continuously for at least three years preceding—five acres indeed
having been in corn since 1899; and the other of forty-five acres
of oats, thirty-five acres of which had been in corn for three years
preceding, and ten acres continuously in that crop since 1899 until
sowed to oats the present spring.

April 27 several nests of Lasius alienus were explored, each
containing numerous root-louse eggs and some root-lice. Above
and immediately about the ants’ nests the smartweed was withering
and the roots were drained of sap, and in many cases blackened and
decayed. The tunnels of the ants extended sometimes as far as a
foot and a half from the main entrance, and ranged irregularly from
a depth of an inch to about six inches. The root-lice were mainly
on smartweed (Polygonum) roots, from sixteen to twenty on a
single plant. In that part of the field which had been six years in
corn and was to be planted to the same crop again this year, eighteen
nests were found within a distance of two hundred hills; and in
that part which had been in corn for the three preceding years, thirty
nests were found between two rows three hundred and fifty hills
in length. ‘Twelve of the nests were explored in these parts of the
field, five in the first mentioned and seven in the second. ‘The ants
in these colonies ranged in number from eighteen to one hundred
and twenty-six, averaging fifty-seven each. Four of them contained
from one hundred to three hundred larve and eggs of ants. All
were plentifully stocked with the eggs and young of root-lice,
whether in all cases, or even in the majority, those of Aphis maidi-
radicis (the corn root-aphis) it was impossible to say with cer-
tainty at that early date. Root-louse eggs varied in number from
seventy-five to two hundred and seventy-five per nest, averaging
one hundred and sixty-one, and young root-lice were found in num-
bers varying from two to seventy-eight, with an average of thirty-
five, a total average of one hundred and ninety-six root-louse eggs
and young to each ant’s nest.
May 1, root-lice nearly full grown, together with many young,
were taken from roots of smartweed and ragweed (Ambrosia). in
that part of the field sown to oats this spring but in corn for three
year preceding. ‘Two hundred oats plants were examined on and
near the nests of ants containing root-lice, but not a louse was found
upon them. Here again smartweeds near the nests of ants were
withered and the roots were dead or actually gone. Cavities and
gangways had been made by the ants beside the roots of these weeds.
The first root-louse of the second generation was seen in the field

22

May 3, although the eggs of the preceding year were not yet all
hatched.

At this time an interesting and important comparison was made
between the contents of ants’ nests in fields of corn last year and
those on which a single crop of oats had been raised. Every nest
of the former contained numerous root-lice or their eggs, while thir-
teen nests of Lasius alienus found in the oats field in corn for the
three preceding years were carefully explored, but not an aphis
could be found in the possession of the ants. Later, a single colony
of thirty-six ants was found with no eggs but with seventy-eight
root-lice in their possession. ‘These had very likely been carried in
from an adjacent part of the field. In the absence of root-lice the
ants seemed to be maintaining themselves, in part at least, by cap-
turing beetles and insect larve, the remains of which were found in
their nests.

On the other hand, in the oats fields which had been in corn for
some years before, ants were now less abundant than in the adjacent
corn, and the eggs and young of root-lice were common in their
nests. In fourteen nests explored May 3, eight hundred and eighty-
six ants were found, an average of sixty-three per nest, together
with five hundred and sixty-five eggs and eight hundred and eight-
en young of root-lice. This was an average of ninety-eight to
each nest, and is to be compared with the average of one hundred
and ninety-six root-lice and root-louse eggs per nest in the adjacent
fields of corn.

By May 8 the second generation of the root-lice was abundant
in the oats fields, but none of them had as yet acquired wings. Heavy
rains fell on the roth and 11th of May and at occasional intervals
thereafter, and the muddy fields were not revisited until May 18.
Then many ants were crawling about and making new burrows
in the ground (each of which contained from two to ten ants,
and no root-lice. Specimens of the latter, dropped near these
new-made burrows, were promptly pounced upon by ants and
carried under ground. ‘The root-lice seemed to be less numerous.
than before, as if affected by the rains. On the 22d of May the
fields continuously in corn were visited again, and fourteen nests
of ants were dug out and the contents caught and counted. Five
hundred and seventy-one ants were found in these nests, an aver-
age of forty-one each, and six hundred and fifty-five ant larve
in eight of them. ‘The aphis contents, on the other hand, had
dwindled greatly, consisting of forty-six wingless adults, thirty-
three pupze, and one hundred and seventy-three young, a total aver-
age of thirty-seven to each ant’s nest.

23

May 30 the oats fields were revisited by Mr. Kelly, in companys
with Mr. C. A. Hart, whom I had sent out from the office to inspect
the situation, and to the astonishment of both not an ant nor an
aphis could be found in the whole forty-five acres of this crop. As
recent rains had fallen, it was at first surmised that the ants’ bur-
rows had merely been obliterated, but protracted search on the two
following days, which were warm and bright, gave the same nega-
tive result. The smartweeds were now virtually all dead, and the
oats were tall enough to shade the ground. The entire ant and aphid
population of these fields had evidently abandoned them, and could
not be traced.

June 22 another visit was made to this field, and prolonged
search again failed to discover a single insect of either kind, al-
though in the adjoining corn both ants and aphids were numerous,
and in one of the fields, where nearly every hill was infested, con-
siderable injury was being done. ‘The field of corn which had been
in oats the preceding year, and in which on previous visits ants were
found but not a root-louse, was now badly infested, and this fact
offered the only possible hint of the whereabouts of the insects which
had left the oats the preceding month.

Observations im the Thompson Field.—For further evidence
concerning the effects of a change from corn to oats, observations
were made by Mr. Kelly on two adjacent fields of forty acres each,
one in corn this spring and the other in oats, both fields having been
in corn continuously for the three years preceding, and both being
heavily infested by Aphis maidiradicis May 8, when first selected
for this comparison.

May 19, the ground being very wet after a recent rain, eight ant
hills were examined in the oats field and their contents collected.
Three hundred and thirty-four ants were obtained, an average of
forty-two to each colony, and one hundred and sixty-seven aphids,
an average of twenty-one to each ant’s nest. Fifty of these aphids
were wingless adults and eight were pupe, the remainder, of course,
being young in various stages. ‘These were contained in seven of
the nests, one nest being without root-lice. The number varied from
two to forty-six to a nest.

The other field had been plowed for corn April 28 to May 5,
and harrowed twice. Hard rains following, it was disked twice
May 19 and 20, and harrowed again just as it was planted. Both
ants and root-lice were found in this corn May 20, but no record was
made of their number or distribution until June 2, at which time a
final visit was made for a comparison of the two fields.

In the oats not an ant nor an aphid could now be found; even
the borders of the field nearest the corn had been completely aban-

24

doned by both. In the corn, from a hundred hills chosen as fairly
representative of the whole field 2156 ants were taken, an average
of twenty-two to the hill, fifty-two of the hundred hills being in-
fested by them. In the same hills 1507 root-lice were found, an
average of fifteen to the hill, forty-three of the hills being infested.
Each ant’s nest contained on an average forty-one ants and thirty-
five root-lice,—less than one root-louse to each ant. The winged lice
in these hundred hills averaged in number twenty-seven per cent.
of all the adults. Collections made on higher and drier parts of the
field were compared with those from lower and wetter portions, but
gave no marked difference in respect either to the ants or aphids, or
to the ratios of winged to wingless adults.

Observations made in this field correspond precisely, it will be
seen, to those reported from the Barto fields with reference to the
total disappearance, late in May, of ants and aphids from oats grown
on old corn ground.

ADDITIONAL MISCELLANEOUS OBSERVATIONS.

April 11, at Bradford, an ant’s nest was explored, the burrows
of which extended throughout an area approximately three by four
feet, and to depths varying from one to four inches. Ants were dis-
tributed everywhere through the soil within these dimensions, but
all the aphis eggs seen were collected at one place.

April 12, a nest of Lasius alienus, around which a few young
smartweeds (Polygonum persicaria) about one inch high were scat-
tered, was watched by Mr. Kelly for two hours and a half. An ant
coming up with a young root-louse in its mandibles carried this
about two feet and placed it on a smartweed very near the ground,
and the root-louse, after crawling about half an inch, thrust its beak
into the plant. Six more ants transferred a single root-louse each
to smartweeds above ground within the next twenty minutes. In
about an hour and a half one of the ants returned its root-louse to
the nest, and thirty-five minutes later all had been carried back. One
of these ants, which was so marked that it could be recognized on
its return, recovered and carried to the nest the same root-louse
which it had previously brought cut.

Another nest of the ants was carefully explored on the 13th.
The burrows were found to vary in diameter from one sixteenth to
three eighths of an inch, and to range from one to six inches below
the surface. In a cell a quarter of an inch in diameter were many
eges and a few young of the corn root-aphis. When these were dis-
turbed the ants seized them and retreated to more distant parts of

\

25

their habitation. About two inches from this collection of eggs a
smartweed root had been exposed by the ants under ground, and on
this about fifteen of the root-lice were feeding.

In another nest explored on the same day the burrows were
from one tenth to one eighth of an inch in diameter. Under a space
of two square feet four clusters of root-louse eggs and some recently
hatched aphids were found. Six young aphids on the roots of a
smartweed in one of these burrows were promptly seized by the ants
and carried farther into their retreat. At four o’clock p. m. most of
the ants had retired for the day, but two brought out an aphis each,
taking it back, however, in less than two minutes. ‘Twenty-two
ants were found in this nest, together with a bunch of aphis eggs
about as large as a pea. ‘Two inches from this mass of eggs was a
sprouting smartweed that had not yet broken ground, and on it were
a number of young root-lice. When exposed by digging, the ants
immediately seized them and carried them away. Roots of smart-
weed, grasses, and ragweed exposed in burrows, sometimes had no
root-lice on them, although in one case a root-louse was found on a
ragweed root.

May 5 ten nearly grown aphids were taken from a smartweed
root and placed on the bare ground.. They crawled actively about
and two of them entered a crack in the earth as if to escape the light.
One of these was found by an ant which carried it away. Two small
ones crawled about four feet and stopped as if exhausted, but two
larger aphids traveled more than ten feet in an hour and twenty min-
utes. All these aphids were seemingly averse to the light, and
crawled away from the sun.

May 8 several young of the second brood were found. Three
full-grown stem-mothers were unearthed, near one of which were
four young, and near another, two. The third was in the act of
giving birth to an aphis, of which an ant took possession as soon as
it was born and carried it to a new plant. Presently all the other
young were carried away by ants and placed on plant roots. A
second aphis was born from the same mother within forty minutes
after the first. ‘This also was soon carried away and placed on a
fresh plant.

On the 9th, which was cool and damp, a heavy rain having fallen
during the morning, the ants were seen taking the root-lice from the
old smartweed roots—which were now dead and dry or even de-
cayed—and placing them on the roots of younger plants.

On May 12 Mr. Kelly took a corn root-aphis from a plant and
placed it on the ground. A root-louse ant (Lasius alienus) found it
presently, carried it away to a distance of four feet, placed it on the

26

ground, made a burrow to the root of a plant of foxtail-grass (Se-
taria) and put the root-louse on the plant, where it was afterwards
found by digging. Presently she took the root-louse away again to
a new place, and finding a root of foxtail exposed in a crack of the
earth she placed the aphis on it, and there the insect remained until
the observation closed.

April 23 a Harpalus caliginosus was found in an ant’s (Lasius
alienus) nest, where it was surrounded by several fragments of ants
which it had evidently been eating. April 26 another harpalid was
captured under a board, where it was eating ants and was sur-
rounded by fragments of those already devoured.

April 29 the remains of four seed-corn beetles (A gonoderus pal-
lipes) were seen 1n an ant’s nest which contained about two hundred
ants, but no root-lice. May 15 a Lasius alienus was found feeding
on an earthworm.

Systematic breeding-cage experiments, made in my insectary at
Urbana with eggs and aphids sent in by Mr. Kelly, gave results sub-
stantially consistent with those previously published* as to periods
and succession of generations, but yielded a much larger number
of young for each mother aphis than I have previously reared. The
largest number hitherto reported was fifteen young, and the average
reared was much less than that. This year, however, thirty-six
adults bred between July 1 and September 14 produced from twenty
to eighty-four young each, with an average of forty-one to each par-
ent, and this may probably be accepted as the known rate of multipli-
cation under favorable conditions. The period of development from
birth to reproductive maturity, as shown by the birth of the first
young, varied from seven to ten days for twenty-three specimens, the
average being 8.4 days. The time from the appearance of the first
young of any parent to the birth of the last young of the same
parent varied, in thirty-six cases, from 6 to 20 days, with an average
of 10 days, and this may be taken as the ordinary length of the
reproductive period in midsummer under insectary conditions.

GENERAL DISCUSSION OF THE RESULTS (TABLE V.).

The most pronounced effect of an early treatment of the soil for
the control of the corn root-aphis was produced on the Coolidge
farm in 1904, where disking three times and harrowing once re-
duced the number of hills infested by ants by sixty-four per cent.,
and those infested with aphids by eighty-two per cent., and the num-
ber of insects, both ants and aphids, by ninety-two per cent. each.

*Eighteenth Rep. State Ent. I11., pp. 63-64.

27

In this case the field was disked on the 18th, 21st, and 25th of May,
harrowed on the latter date, and examined June 9, fifteen days after
the last treatment.

More remarkable, on the whole, was the effect of once harrowing
with an Acme harrow May 22 and 23, after numerous heavy rains
from the 15th to the 20th of May, 1905. Here a single treatment
(Experiment 3, Table V.) with the disk harrow, used as soon as
the ground was dry enough to work properly, reduced the number
of hills infested by ants and aphids by fifty-eight per cent. and sixty-
four per cent. respectively, and the number of insects in the field by
ninety per cent. for the ants and eighty-nine per cent. for the aphids.

The least effective treatment, according to Mr. Kelly’s notes, was
a single disking, May 5, of plat Ai on the Hinman farm (Table III.),
which, as shown by a comparison with C 1 of the same table, seems
to have reduced the number of hills infested by only sixteen per
cent. for the ants and seventeen per cent. for the aphids, and the
number of insects by four per cent. for the former and fourteen per
cent. for the latter. As these plats were not examined until May
31, that is to say twenty-six days after the treatment, these figures
probably ought not to be taken into account. It was hardly to be
expected that the original difference between check and experi-
mental plats should continue unchanged during this interval of
nearly four weeks.

Five of the pairs of plats brought into comparison differed in re-
spect to treatment only by the fact that the experimental plat was in
each case treated with a disk harrow once more than its correspond-
ing check. If the ratios for these five plats be averaged, it appears
that the result of a single disking in 1905 on the Hinman and Fin-
negan places may be described in general terms as reducing the
number of hills infested by forty-four per cent. for the ants and fifty-
one per cent. for the aphids, and the number of insects by fifty-seven
per cent. for the ants and sixty-three per cent. for the aphids. Or,
still more generally speaking, it may be said that the average effect
of a single treatment with the disk harrow was to reduce the number
of infested hills by a little less than half, and the number of insects
in the field by about two thirds. If, in view of the doubtful charac-
ter of one of these comparisons above mentioned, in which nearly
four weeks intervened between the experimental operation and the
inspection of the plats, we omit this*case from our calculation, this
statement may be revised to the effect that a single disking may be
expected to reduce the number of infested hills by something more
than half, and the number of insects in the field by nearly three
fourths.

28

The effect of twice disking, as shown by a comparison of C I
and B 1 of the Hinman field (Table III.) was to reduce the number
of infested hills by fifty-nine per cent. for the ants and seventy-five
per cent. for the aphids, and the number of insects by sixty-five per
cent. and eighty-four per cent. respectively. As these two treat-
ments were given, however, on the 5th and 8th of May, and the
inspection was not until twenty-three days later, it is probable that
the full effect of this treatment does not appear in this statement of
the result, since there was ample time for the treated plats to become
restocked by both ants and aphids by multiplication and migration
_and by the establishment of new aphis colonies from winged parents
developed during this interval.

The general conclusion to be drawn from this whole series of ex-
periments is to the effect that the number of both ants and aphids
may be readily controlled and the injuries to corn in great measure
prevented by thorough and frequent stirring of the ground pre-
vious to corn planting, and that the disk harrow or its equivalent is
much the best implement for the purpose. Indeed, the treatment
most effective for the destruction of the root-aphis and its attendant
ant in spring is in great measure that which will be found most use-
ful as a thorough preparation of the soil for corn, the main differ-
ence being that a thorough overturning and stirring of the soil is
the essential thing for the destruction of the root-louse, while it is
sufficient for the corn plant if the earth be merely pulverized in
place. ?

If the corn farmer will prepare his old corn ground early and
thoroughly, using the plow and the disk harrow by preference, he
should have little trouble in the beginning of the season from the
corn root-aphis, and so fast and so far as the general community acts
in accordance with this idea, to that extent will later injuries by this
aphis be forestalled. It is in this as in many other cases, one acting
by himself alone can accomplish relatively little even for his own
protection; the welfare of each depends on intelligent cooperation
by all.

It is further to be concluded from the observations here re-
ported, that if infested corn ground be planted to oats, the root-lice
will leave it or perish in it (just which we do not yet know) by
the end of May. A rotation with a short period in corn must con-
sequently act to check the multiplication of this insect and to dimin-
_ ish its injuries to corn.

29

TABLE V. COMPARATIVE EXHIBIT OF RESULTS OF TREATMENT,

Experiment

4. innegan.......

5. Hinman

Differential Treatment

Disked three times, harrowed once..

Plowed once, harrowed three times.
Spaded once, rolled once.............

Disked once, (after heavy rains)....
Disked once, (after harrowing)......

Disked once, (after previous disking)

Drskedrtwacescfoc scat cae see esd aie

Percentages of Reduction

Ants Aphids

Hills Number | Hills Number

in- of in- of
fested insects | fested insects

64 92, 82 92

60 nell 75 81

58 90 64. 89

52 63 12, 81

33 42 41 43

59 65 75 84

30

FIELD EXPERIMENTS FOR THE PROTECTION OF CORN
AGAINST CHINCH-BUG INJURY.

BARRIER EXPERIMENTS.

Experiment of 1895.—In my ninth entomological report, pub-
lished in 1898, I gave.an account, in an article on ‘‘Midsummer
Measures against the Chinch-bug,’”’* of a field experiment made in

*Twentieth Rep. State Ent. I11., pp. 37-44.

1895 for the destruction of that insect as it passes in June and early
July from small grain to corn. The measures used in this experi-
ment were a combination program of a dusty furrow for the ar-
rest and destruction of chinch-bugs in dry weather, a coal-tar line
with post-hole traps for use when the ground is too wet to pulverize,
and kerosene emulsion for the destruction of the insect on the corn
itself.

This operation, carried on in Effingham county from June 5 to
15 by one of my assistants, was highly successful in the protection
of corn growing adjacent to a heavily infested 20-acre field of
wheat, approximately twelve bushels of chinch-bugs being destroyed
in the process at a cost of less than five dollars for the materials used.

Extreme conditions prevailed at the time of this experiment.
Injury by chinch-bugs to grass, small grains, and corn had contin-
ued in this locality for some years with increasing intensity, and
these insects had become so numerous in the wheat that they had
already destroyed the crop and virtually all other grass-like vegeta-
tion in the field referred to, by the 5th of June. Compelled to leave
the wheat to avoid starvation, they moved out of it rapidly, wholly
deserting it within a very few days. The corn adjacent was thus
exposed to immediate and complete destruction by the invading
horde, and would inevitably have been soon destroyed if active
measures had not been taken to protect it, a fact made perfectly ap-
parent by the fate of other similarly situated fields in the neigh-
borhood.

The weather of the season had been very dry, and it was in-
tensely hot, conditions which, although unfavorable to the infested
crops, were unusually favorable to the easy success of measures for
the destruction of the chinch-bugs. A dusty furrow, readily made
and maintained between the wheat and the corn, trapped the in-
sects in myriads as they attempted to pass from one field to the
other, and the heat of the dry dust in the bottom of the furrow,

dl

fully exposed to the sun, speedily killed them. The coal-tar barrier
was, in fact, required but once, and the kerosene emulsion was used
only to destroy the bugs which had entered the field before the
experiment began and a few which escaped into it in an interval be-
tween a shower of rain and the establishment of the tar line. As the
protected field of corn bore a good crop while other fields in the
neighborhood were almost wholly destroyed, the demonstration of
the usefulness of this method was complete for these extreme con-
ditions.

Experiments of 1904.—Wishing to know, however, what might
be done by similar operations.under more ordinary circumstances,
especially when a chinch-bug outbreak was but just beginning and
when the weather was generally unfavorable to success, I prepared
in the spring of 1904 for several field trials, to be made at different
places in southern Illinois where a previous inspection had shown
that the chinch-bugs were present in numbers sufficient to threaten
more or less injury to wheat and corn. The fields selected were in
four localities: near Carbondale, in Jackson county; near Dubois,
in Washington county; and near Fairman and Odin respectively, in
Marion county.

The experiment was placed in charge of Mr. E. P. Taylor, and
I owe the results here reported to his energy and faithfulness in the
field, and to the fulness and exactness of his notes.

Although the prospect of insect injury was considerable at all
these places in the early part of the year, the weather of the spring
and early summer was so wet and much of the time so cool that the
multiplication of the insects was in great measure prevented, and
they finally became abundant enough to injure corn seriously only in
the Carbondale neighborhood. ‘The whole experiment was faith-
fully carried through, however, at all the above places, and with use-
ful results at each.

At Carbondale, rain fell twelve times and on eleven different days
between June 24 and July 25, and the ground was kept so moist
by rains at all the places mentioned that the dusty furrow could not
be long maintained at any of them. As a consequence, the tar line,
with post-hole traps, was used throughout, and kerosene emulsion
was only occasionally applied, as found necessary. ;
; The tar lines laid at these various places aggregated more

than a mile and a half in length (508 rods, exactly), and were main-
tained for periods varying from eleven to twenty-eight days, the
total of this procedure being equivalent to the maintenance of an
effective coal-tar barrier a mile in length for twenty-seven days.
Post-holes were dug from one to two feet deep at a usual distance of

32

twenty feet apart along all these lines; and besides the continuous
coal-tar strip, diagonal leaders about a foot in length were laid from
each hole outwards in two directions, as shown in the accompany-
ing diagram (Fig. 2, p. 131).

SUMMARY OF CONCLUSIONS.

As a general outcome of the work at these various places, it
was demonstrated that an effective barrier against the movement
of chinch-bugs may be maintained for four weeks with coal-tar,
poured along a strip of ground properly prepared, at a cost for
materials of seven cents a rod, or $22.40 a mile, and that virtually
all the bugs approaching these lines may be trapped and killed in
post-holes properly placed for the purpose.

The time for which this barrier must be kept intact will vary
from ten days, the period found necessary in the very dry weather
of 1896, to thirty days, as required this year. The labor necessi-
tated is that of raising a ridge by plowing a back furrow between
the infested field and the one to be protected, smoothing and packing
this strip with a light roller or by hand, digging a row of post-holes
at intervals of about twenty feet, and laying the lines of tar by pour-
ing it upon the ground from a can with a tubular spout. This line
was renewed whenever it became dry or hard in the sun, or when it
was covered with dust in windy weather or washed away or cov-
ered with mud by rains. It was necessary to pour fresh tar along
the line from one to three times a day, the average at all places for
the month being three renewals every two days.

USE oF KEROSENE EMULSION.

Where chinch-bugs had entered corn before the experiment was
begun, and where, through accident or mismanagement, they es-
caped across the barrier, they were effectively treated with a four
per cent. kerosene emulsion. It was shown that a mixture suffi-
ciently complete and lasting for the purpose could easily be made
by stirring the kerosene and the soap solution together with a stick
or paddle, and that this emulsion could be conveniently applied by
sprinkling or throwing it on the infested plants with a whisk-broom,
or even with the bare hand. ‘Thus prepared and used, the four
per cent. emulsion was as strong as the corn would stand without
some injury, and was sufficient to kill all the chinch-bugs which it
touched.

The only notable failure of this method to destroy the chinch-
bugs against which it was used, occurred where the infestation of

33

the wheat field was slight, and where so many grass-like weeds had
sprung up in the wheat that they afforded food to the bugs in the
field at harvest sufficient to detain them there for several days. There
was virtually no migration on foot out of this field, the chinch-bugs
generally lingering until the appearance of their wings enabled them
to scatter by flight to more favorable breeding grounds.

At Carbondale, where they were the most abundant, the corn ad-
jacent to infested wheat was saved from all injury worth noticing,
while the crop on some other fields in that region not protected,
was completely destroyed for many rods inward from the edge of
the field, and badly injured for a considerable distance further.

The Carbondale Experiment.—On a farm situated one mile west
of Carbondale, belonging to Mr. Robert Thorpe and referred to
in this account as the Thorpe farm, was an irregularly shaped field
of one hundred and forty acres of wheat which in June, 1904, was
generally and considerably infested by chinch-bugs, sufficiently so
to threaten notable injury to the wheat crop itself and the destruc-
tion at harvest-time of much of the corn adjacent. Indeed, by the
last week in June the wheat: was ripening irregularly, turning
brown in patches where the chinch-bug was most abundant, in ad-
vance of the general ripening of the field, and from these patches
the insects were already beginning to move into other crops.

A corn field of twenty-seven acres cornered into this wheat at
the northwest in such a way that the division line of the two crops
measured three hundred and seventeen yards on the east and three
hundred and thirty-eight yards on the south, the remainder of the
southern side being bounded by woodland. In the southwest cor-
ner of this wheat was another field of corn of only four acres, so
placed that it was bounded by infested wheat only on one side for
about one hundred yards. A third field of corn, on an adjacent farm
belonging to Ralph Thompson, was also exposed to invasion from
the wheat field for a distance of about one hundred and forty yards.
This corn was south of the wheat, from which it was separated by
a roadway of the usual width.

The situation here was complicated by the fact that in the north-
west field of twenty-seven acres of corn a large pile of waste from
a corn shredder had been left the preceding fall, in which quantities
of chinch-bugs had passed the winter. Coming out in spring, many
of these laid their eggs in the young corn, which thus became im-
mediately infested from within by the first generation of the year.
A part of the wheat bordering this field on the south had ripened
early, owing perhaps to chinch-bug injury, and the bugs from this
vicinity had already begun to invade the corn before our experiment

b4

was begun, infesting a strip about thirty yards in length and seven
or eight rows deep.

To prevent the further entrance of aM es into these three
corn fields from without, 1080 yards (about three fifths of a mile)
of impassable barriers were required, with approximately 160
post-hole traps distributed along them; and to destroy those already
in the field before our work began it was necessary to spray a part
of the northwest field with kerosene emulsion.

When these premises were taken in charge for our purpose by
Mr. Taylor, June 23, 1904, the wheat was already nearly ripe, and
harvesting began a few days later, continuing until July 7. The
chinch-bugs were at first by no means hurried in their movement
out of the wheat, as there were still grassy weeds in the stubble to
detain them, and the frequent showers of the following month kept
this vegetation in good condition continuously. The movement
towards the corn was well marked, however, from the beginning, and
prompt measures were necessary to protect that crop. There was
also urgent need for a destruction of chinch-bugs already in the
corn, and this was the first task undertaken, kerosene emulsion being
made up to June 23 in a rather rough-and-ready manner by stirring
the kerosene and soap-suds together vigorously for several minutes
with a stick. This mixture was then flirted on to the corn with the
naked hand at a rate of about a pint to every three hills. The first
mixture contained five per cent. of kerosene, and was evidently too
crudely made, proving injurious to the corn, especially where it was
held in the conical cavity formed by the terminal tuft of leaves. It
was estimated that about twenty-five per cent. of the stalks treated
on this first date were damaged more or less. A four per cent. mix-
ture, on the other hand, as applied on the 24th of June, did no dam-
age to the plants, and is reported to have killed the chinch-bugs as
soon as it touched them. ‘This emulsion was used from time to
time thoroughout the whole period of the experiment in parts of
two fields of corn where the bugs made their way around the ends
of the barriers in number to require special measures for their de-
struction.

An effort was made at the very first to use a dusty furrow as a
barrier, with post-holes dug in the bottom to trap the bugs, and
about one hundred and sixty rods of such furrows were made June
23 to 25 on the eastern and southern sides of the northwest field,
and on the west side of the four-acre patch. The ground was deeply
plowed and thoroughly harrowed in a four-foot strip, and a ridge
was formed by making a back furrow down the middle. A log was
then dragged through the center of the strip until a dusty groove
—4

35

or furrow was made several inches in depth. In the bottom of this
holes were dug with an ordinary post-hole digger at intervals of
- twenty feet. The ground was too damp, however, even at first,
to make a satisfactory barrier, and heavy rains falling on the 24th
and 25th of June compelled a prompt abandonment of this part
Ofthe Operations.

Coal-tar lines, substituted for the furrow because of the weather,
were laid on the 24th to the 26th so far as needed to protect fields
of corn on the Thorpe farm. June 30 it became necessary to lay
also a similar line for a short distance along the border of the south
field on the Thompson farm, as the hungry bugs were at this time
crossing the road in large numbers on their way to the corn. All
these tar lines aggregated about two hundred rods in length, and
were maintained in an effective condition around the different fields
from eighteen to twenty-eight days. It was necessary to renew
them, on an average, twice every three days. One hundred and
forty-five gallons of tar were used in all, at a cost of $8.85. The
supply of tar being temporarily exhausted July 9, kerosene was
poured along the dried-out line on the ground, with the effect to
soften it and to keep it soft for thirty hours. Besides the hardening
of the tar by exposure to the sun, the barriers were occasionally
bridged by dust blown into them, and broken by rains which some-
times washed them away in spots or covered parts of them with mud.

It is needless to say that no chinch-bugs crossed the tar line as
long as it was kept reasonably fresh. The post-hole traps, into which
the bugs were led by diagonal lines or leaders of tar, worked effect-
ively, and bugs accumulated in them in variable amounts up to a
quart for each hole. Here they were readily killed by pouring a
little tar-water or kerosene upon them.

The movement of the bugs was greatly influenced by the
weather. On warm and sunny days they sometimes began to travel
not long after sunrise and continued until near sunset, but in cooi
and cloudy weather they moved later or not at all, and the traps con-
sequently caught few or none. Whatever the weather, they never
traveled at night. July 1 to 5, when the last of the wheat was being
cut, they left the field more rapidly, and more of them were then
destroyed than at any other time. By the 24th of July the move-
ment was practically over, most of the bugs remaining having fin-
ished their growth and got their wings. Many of them had but
recently transformed, as shown by their paler color, and pairing
for the next generation was actively in progress.

The final result of the above operation is given in Mr. Taylor’s
report of conditions July 30, at which time he says that “all the

36

fields of corn which have received the protection of our barriers are
quite uninjured and practically free from chinch-bugs.” ‘The small
sprinkling of the insects to be found in any of the fields had doubt-
less flown in as they reached maturity. The actual cost for coal-
tar was $8.85, and for kerosene and soap it was $2.55. The labor
necessary to the operation was 28 days’ work of a man and 2
of a team, the latter for making the back furrow, for rolling the
ground, and for hauling the tar and kerosene emulsion to the field.

It should be noticed that this defensive operation was as com-
plete and as expensive as would have been necessary if the chinch-
bugs had been ten times as numerous in the wheat. ‘That is, the
labor and cost would have been no greater to protect the corn against
the danger of a loss ten times as great as it would have suffered if
the bugs actually in the wheat this year had been allowed to go their
way.
The Fairman Experiment.—Near Fairman, in Marion county,
a large field of wheat on the farm of Mr. Wm. Meredith, moderately
infested by chinch-bugs, was selected for experiment. ‘This field
was bordered for eighty rods by a field of corn, from which it was
separated by a wire fence. Operations were begun here June 30,
when the wheat was already ripe, harvesting being in progress at
the side of the field farthest from the corn. To protect the latter
crop a double barrier was made within the margin of the wheat
field, where two swathes of the grain were cut to give room for
the operation.

A strip five feet wide the whole length of the field was plowed
and thoroughly pulverized, and a deep dusty furrow was then made
in the middle of it; and a strip two feet outside this was also pre-
pared for the tar line, various parts of it by different methods.

Preparation of the Dusty Furrow.—Although wet weather pre-
vented the continuous use of the dusty furrow as a barrier to the
movement of the chinch-bugs, and compelled a reliance on the coal-
tar line instead, the method used in preparing the former is well
worthy of description. First, a furrow was plowed about seven
inches deep and fourteen inches wide the whole length of the field in
the center of the stubble border. On the return a second furrow
was made immediately beside the first, the dirt from which was
thrown back into the first furrow, leaving no unplowed earth be-
tween them. ‘The land was then widened by plowing back and forth,
throwing the earth toward the center each time, until six furrows
had been made. ‘This strip, about six feet wide, was then harrowed
ten times with a common disk harrow, and twice with a straight-
toothed harrow, leaving the ground level, thoroughly pulverized,

37

and free from clods and weeds. Next, near the center of this pul-
verized strip a deep dead furrow was made by plowing twice back
and forth in the same line,—once in each direction with an ordinary
fourteen-inch plow and once with a small diamond plow,—and in
the ditch so made, a log eight feet long and eight inches through was
dragged by a single horse (a mule would have been better) until the
sides of the ditch were pulverized to the finest dust. This work
would require, for an eighty-rod line, the labor of two men and a
team for a little more than half a day. The average cost of a dusty
furrow constructed as above described, would be practically three
cents a rod, as shown by the actual labor of man and horse used on
this eighty-rod line.

This furrow was finished July 3, and caught and held the chinch-
bugs generally during that day and the following; but July 5 a heavy
rain fell which put it out of service, and even the following day the
ground was too wet to renew it by dragging again with the log.
Equally heavy rains falling on the 8th and on the 11th discouraged
further work.with it, and it was practically abandoned in favor of
the tar line.

When in use, some method of destroying the bugs entrapped is
necessary. In bright summer weather the dust in the bottom be-
comes so hot as to kill all the chinch-bugs except those with wings,
and many of these also will succumb. Otherwise, shallow pits may
be dug with a post-hole digger or spade at intervals in the bottom of
the furrow, care being taken to restore the dusty surfaces disturbed
in this operation. The harassed bugs will accumulate here in quan-
tities, and may be killed by pouring a little kerosene upon them.
Experiments described on another page of this report indicate that
the bugs caught in the dusty ditch may also be quickly killed by a
brief exposure to a kerosene spray or to the flame of a gasoline
torch.

DIAGRAM OF CHINCH BUG BARRIER

Post HoleTrap(Diam8 in)

i _“”_PostHole Trap Line

Smooth é = = = i =
Path or %& —_ — prea ETE ma Tar Line

Wz vey"
. i

i

Pulverizéd2

m. Dust
“ Furrow

1

<3
6342 3.

Infested Wheat
Fig, 2. Dusty furrow, and coal-tar line, with post-hole traps and diagonal “leaders” of tar
Preparation of the Coal-tar Line.—To receive the tar line it is
necessary to have a smooth hard band of earth like a well-beaten
path, into which the tar will not readily sink. This should be about

38

level with the adjacent surface or a little above, as otherwise the
line is likely to be bridged by dust and rubbish blown upon it. ‘The
effectiveness of the barrier depends, indeed, largely upon the prep-
aration of the strip of earth along which the tar is to be poured.
Such a path was prepared in six different ways on as many sections
of the line.

Beginning at one end, a strip ten rods long was prepared beside
the fence by simply scraping smooth with a hoe and sharp spade.
Where the ground is hard, and grass and weeds form a thick mat,
one man will not ordinarily clear over five rods an hour. ‘This
method is laborious and expensive, and would only be necessary
where a team could not be used. It would cost for labor about two
cents a rod.

The second section of ten rods was prepared by plowing two
very shallow furrows with a fourteen-inch plow, merely skimming
away the weeds, grass, and surface roots. Both these furrows
threw the dirt towards the wheat field, leaving a belt about two
feet wide free from weeds and grass, and separated from the wheat
by the dirt thrown over. The work was thus done rapidly, but by
this method the bare strip is left lower than the general surface and
is liable to be covered in places with dust and weeds by the wind.
It must also be smoothed here and there with a hoe before the tar
is laid down. Eighty rods can be prepared in this way by one man
and a single horse in half a day.

The third section of ten rods was made ready by plowing a
back furrow in the stubble and beating the ridge of earth flat and
hard with spades. This was one of the most satisfactory of the
methods used, as by it the tar line is placed on a ridge where it is
not likely to be bridged either by winds or rains. The comparatively
loose earth will at first absorb the tar more freely than the hard bot-
tom of a furrow, but this difference is not noticeable after a few
days. A ridge of this kind may be more rapidly prepared by using
an inverted trough-like drag of planks, weighted if necessary, to
compact the earth, as has been done in Kansas on a large scale.
This will take, for an eighty-rod line, the work of a man and team
for about half a day.

The fourth ten-rod section was prepared by plowing a very shal-
low furrow with a single horse along the edge of the grass in the
headland next the fence, throwing the dirt upon the stubble. This
was not a satisfactory operation, however, as it left too narrow
a smooth surface.

The fifth section, forty rods in length, was prepared by simply
scraping away the weed and grass roots as clean as possible with an

og

ordinary farm scraper, making a strip about two feet wide, one or
two inches below the general level. It was necessary, however, to
scrape the surface afterwards with a shovel or hoe, as many irreg-
ularities were otherwise left to carry the tar in all directions. The
labor of a man and team for half a day would be required to pre-
pare eighty rods in this way.

Finally, the sixth section, eighteen rods long, was made in
meadow land by plowing two shallow furrows, throwing the dirt
outward in a way to leave a level dead furrow about two feet wide,
and smoothing and leveling the bottom more exactly by hand.
This is a rapid and satisfactory method of preparation where a
barrier can be made in sod with room to work a team.

The tar line was made by pouring from a watering can a slender
stream of tar continuously along the ground. Holes were then dug
with an ordinary post-hole digger to a depth of about a foot and at
a distance of twenty feet apart. "They were placed on the stubble
side of the line, and short diagonal lines of tar were laid from each
hole to the right and left in a way to conduct chinch-bugs approach-
ing the line to the hole itself. Six gallons of tar were needed to
construct this barrier along the eighty-rod boundary. During the
period of twelve days covered by this experiment, the tar line was
renewed eighteen times in all, as many as three times a day at first, .
while every other day was sufficient towards the end of the period.
Fifty-five gallons of tar were used in these eighteen operations,
an average of three gallons for each time. ‘The cost of the tar for
this period was $2.40, or twenty cents a day for the twelve days.
This line was of course effective from the first, and bugs were
continuously caught in the holes along it, where they were easily
killed with tar-water or kerosene.

Dubois and Odin Experiments——At Dubois, in Washington
county, an irregular field of corn containing twenty-eight acres was
protected from invasion by chinch-bugs from two fields of wheat
adjoining it. On the east side along a boundary line of two hun-
dred and fifty yards a double barrier was constructed, a furrow next
the corn and a tar line with post-holes immediately outside. ‘To the
west and north a tar line was laid seven hundred and sixteen rods ~
in length, and post-holes were dug every twenty feet. Although
the chinch-bugs proved not to be sufficiently numerous in the wheat
to have caused any great injury even if they had escaped into the
corn without hindrance, these barriers were as carefully maintained
for eleven days, from June 29 to July 10, as if the salvation of the
corn depended upon their efficiency.

40

At Odin was a small field of infested wheat, containing four
acres, with corn bordering it to the north and west. A tar and post-
hole line was carried along these two sides for about a thousand
feet to prevent the passage of the bugs across the boundaries.

The conditions and results at both these places were so similar
to those at Fairman that no detailed account is necessary. At Odin
a simple method was made use of for preparing the ground for the
tar. A heavy plank was dragged endwise back and forth about teri
times along the edge of the wheat, thus smoothing and packing well
a strip two feet wide. With a short-handled shovel the ground was
then packed and pounded to a hard surface, in which a narrow and
shallow groove was made with the shovel handle for the reception
of the tar. This was poured in a stream the size of a lead-pencil
from the spout of a watering-pot from which the sprinkler had been
removed. ‘The line so laid spread out on the ground to a width of a
half to three quarters of an inch.

EXPERIMENTS WITH FLUID INSECTICIDES.

In my first report, the twelfth of this office, published in 1883,
is a description of the first attempts made to destroy chinch-bugs
by means of kerosene mixtures. In the operation there reported,
nineteen experiments were made, mainly with emulsions varying in
strength from two and a half to six and two thirds per cent. of kero-
sene, but partly with mechanical mixtures of the crudest kind.

These insecticide fluids were sprinkled upon infested hills of corn
during the last days of July, partly transplanted hills which had been
removed to my office laboratory and partly hills in the field isolated
by surrounding them with barriers of boards and coal-tar impassable
to insects on foot. Proper checks were kept in all cases of hills
treated precisely like those under experiment except that plain water
was substituted for the fluid insecticides. A single additional experi-
ment was made with strong soap-suds to which no kerosene had
been added.

The general result of a single application of any of these mix-
tures was the destruction of about eighty per cent. of the bugs on
the corn at the time, the remaining twenty per cent. being either
protected by their position from contact with the insecticides or re-
viving after a time without noticeable injury. Most of the escaping
specimens were apparently on the ground under clods of earth
when the corn was treated.

Frequent use has since been made of the kerosene mixtures in
field experiments by ourselves and by other entomologists, partic-

41

ularly for the destruction of chinch-bugs accumulating on the outer
rows of corn as they move into the fields from wheat or oats at
harvest-time. This insecticide method, however, is mainly useful as
an adjunct to the barrier method already described.

With a view to testing this operation on a comparatively large
scale, I instructed Mr. E. P. Taylor, in charge of my field operations
against the chinch-bug in 1904, to prepare and apply kerosene
emulsion in the field wherever necessary and practicable in his oper-
ations, to keep an account of labor required and the cost of materi-
als, and to observe critically and report the effects of the treatment
upon both insects and plants. Experiments of this kind were made
in early July of that year with both kerosene emulsion and whale-
oil soap.

In the absence of a mixing pump, the kerosene and soap-suds,
two parts of the first to one of the second, were thoroughly mixed by
a simple violent beating with a stick for about five minutes, the ves-
sels containing the fluids being covered with a cloth to prevent spat-
tering. Emulsions so prepared, although doubtless not so perfect
as could be made with a pump, were in every way sufficient for the
purpose, standing for at least two hours without any appearance of
a separation of the oil and water, and doing no damage whatever
to the corn if diluted to contain four per cent. of kerosene. If more
than this proportion of the oil were used, injury to the plant was
likely to result, especially if the upper leaves were treated.

Details of Field Experiments.—At Fairman, July 4, one fifth of
an acre of corn was sprayed with a kerosene emulsion prepared as
above and diluted to contain four per cent. of kerosene. No ap-
paratus was used in making the application, but the fluid was sim-
ply flirted upon the corn by hand. ‘Ten gallons of the mixture were
used in this treatment, equivalent to about a barrel (fifty gallons)
per acre, or approximately one and two thirds ounces per hill. The
amount of kerosene in a four per cent. mixture used at this rate
would be two gallons per acre of corn treated.

Twenty-four hours later none of the plants showed signs of
injury, and great numbers of the bugs were dead upon the ground
and in the cups at the bases of the leaves. Living chinch-bugs
enough remained in this part of the field to extend their attack
gradually inwards, until by July 9, five days after treatment, they
were to be found in small numbers ten rods beyond the area infested
at first. The number remaining, however, was economically in-
significant, since no injury to the corn could have resulted.

A second treatment was applied July 12 to this whole area, now
about three fourths of an acre in all, twenty-four gallons of the

42

mixture being used. A part of the corn was now about two and a
half feet high, and the chinch-bugs were mainly behind the leaf-
sheaths or within the conical cavity at the tip of the plant. ‘The
kerosene mixture was applied in part by hand as before, and in part
by pouring from a common sprinkling can, but the former method
was found the more rapid and also the more economical of material.

As shown by examination the following day, not a plant was in-
jured by this treatment, and only a few bugs were left alive, mainly
on plants with leaves so rolled and curled as to protect the bugs
within them. A careful count was made of all the bugs, living and
dead, found upon ten average hills, including those on the ground
about the bases of the plants, with the result that eighty-eight per
cent. of all found were dead. An additional treatment was given to
the corn still infested, and July 24 the owner of the field, after a
careful examination, found an average of twenty to twenty-five liv-
ing bugs per hill. The corn was at this time beginning to tassel. The
same treatment, would, of course, have destroyed any number of
chinch-bugs with which the corn might have been infested. As the
three quarters of an acre invaded by the bugs was part of a forty-
acre field much of which would have been infested and injured if
this section had not been promptly dealt with, the result of the
treatment was much greater than the protection of the corn actually
covered by it. At the rate at which this treatment was applied it
would take two hours to treat an acre, or an average of five acres
per day. a

At Odin, experiments were made July 6 with solutions and mix-
tures of various strengths to test the effect upon both insects and
corn. ‘The plants were young—only about six inches high—and
the liquid was thrown upon them by hand, care usually being taken,
however, to avoid filling the cavity at the tip of the plant. The
emulsions were made by beating, as before, the kerosene being
heated before adding it to the soap solution.

IKerosene emulsion was applied in dilutions varying from four
to ten per cent. of kerosene, and whale-oil soap was used in solutions
varying from an eighth of a pound to two pounds to the gallon of
water. With a four per cent. kerosene emulsion applied in a way
to drench the entire plant and fill the cavity within the terminal
tuft of leaves, no injury whatever was done to the corn, and the
chinch-bugs were nearly all killed. A similar treatment with a five
per cent. emulsion, however, was injurious to the plants. Some
leaves were wilted at the base the following day, and seventeen
out of the thirty plants treated were finally killed. Still more serious
injury of course followed the use of the stronger mixtures.

43

Whale-oil soap dissolved by boiling at the rate of a third of a
pound to the gallon of water proved too weak to destroy more than
a comparatively small percentage of the bugs. With a half-pound
to the gallon, the bugs reached by the liquid were practically all
destroyed, and none of the plants were killed except where the ter-
minal cavity in the so-called heart was filled, in which case the con-
centration of the solution due to the gradual evaporation of the fluid
caused the leaves to wilt and destroyed the plant. Three quarters
of a pound to the gallon was perhaps a little more effective as an
insecticide, but somewhat more dangerous to the plant. A few
plants which were carefully treated were seen six days afterward
to have been injured slightly, the injured leaves rolling up or grow-
ing in distorted forms. Where as much as a pound and a half per
gallon was used nearly all the plants were killed, and two pounds
per gallon was fatal to every one.

From the above it appears that a solution of whale-oil soap—one
half pound to the gallon—is a safe and successful insecticide for
corn-field use. As its cost, however, is about three times that of the
four per cent. kerosene emulsion, it is scarcely to be recommended
except on the score of occasional convenience. Where a barrel of
the four per cent. emulsion costs thirty-four cents, a barrel of a
half-pound solution of whale-oil soap will cost $1.12.

Such fluid insecticides may best be applied during the cooler parts
of the day, since the plant is less subject to injury then and the bugs
feed more thoroughly. Enough of the liquid must be applied to wet
the insects thoroughly, since otherwise they are likely to recover
from its effects. For a complete operation, two and even three ap-
plications may sometimes be necessary.

EXPERIMENTS WITH THE GASOLINE BLAST-LAMP.

The use of the ordinary plumber’s torch, or some modification
of it, for the destruction of injurious insects on their food plants
seems to have occurred independently to several persons during the
last few! years, and to have been tried with some care as a practical
measure by several disinterested men competent to make exact ob-
servations and to report results without bias or prejudice.

Mr. S. A. McHenry, recently superintendent of one of the horti-
cultural substations of the Texas Agricultural Experiment Station,
is reported to have used it for several years against the harlequin
cabbage-bug, and Professor J. M. Stedman, of the Missouri E.xperi-
ment Station, has also used it against the same insect. Professor
R. H. Pettit, of the Michigan Agricultural College, tried it on the

44

San Jose scale as far back as 1897, publishing in the Bulletin of
the Michigan Experiment Station the earliest report of an exact
experiment with it which I have seen; and Professor Craig, of the
Horticultural Department of Cornell University, has also tried it
on this scale. Professor E. D. Sanderson, formerly of the Texas Ag-
ricultural College and Experiment Station, has used a form of it
on the cotton boll-weevil. Professor Thomas B. Symons, of the
Maryland Agricultural College and Experiment Station, -used it
experimentally on the San Jose scale, and on beetles infesting the
aster. Professor J. L. Phillips, State Entomologist of Virginia, has
also tested it on the San Jose scale with unusual thoroughness; Pro-
fessor F. M. Webster, Entomologist of the Ohio Agricultural Ex-
periment Station, had it tried four years ago by an assistant, Mr.
C. W. Mally (now Government Entomologist in Cape Colony,
South Africa), on a variety of insects, including the chinch-bug;
and two of my own assistants, Mr. E. S. G. Titus and Mr. G. I.
Reeves, have used it on scale insects, caterpillars, and moths; have
tested it for the destruction of fungus parasites of the green leaf;
and have determined its effects on various kinds of vegetation when
applied in a way to kill the insect enemies of the plant. Most of
these experiments are unpublished, but their results have been gen-
erously placed at my disposal for use in this brief discussion.

Although no one of those here mentioned has made a trial of the
gasoline torch for all the insecticide and fungicide purposes which it
might possibly serve, the total results have a considerablé value as
showing definitely some things which can and some things which
can not be done with it, and as indicating the directions in which
further trials may be had if indeed it appears that further trial
is necessary or worth while. Some variation and conflict in the
reports of some of these experiments are evidently due to differences
in the apparatus used, this varying from a poorly constructed and
feeble torch, made in Illinois especially for insecticide work, to a
large and powerful blast-lamp, used in Texas for burning the thorns
off prickly pears.

The idea that exposed insects of small size may be quickly de-
stroyed by the sudden and brief application of a blast of very hot air,
or even of actual flame, without injury to the plant on which they
may be feeding at the time, strikes one favorably at first thought;
and there seems, in advance, to be no obvious reason why this
method may not have a considerable practical value. The living
animal is often more sensitive to sudden heat exposures than the
living plant, and the margin between exposures fatal to each may
in some cases be so wide as to make this method fairly safe in

45

ordinary practice. The smaller the insect, of course the more
quickly it may be killed by the hot blast; and the better the living
tissue of the plant is protected by a lifeless cuticle or a layer of bark,
the longer it may be exposed to this blast without being heated to
the point of injury. Bark-lice on trees and shrubs are thus favor-
able objects for experiment; but where thick-bodied insects, like
caterpillars and large beetles or bugs, themselves covered with a
dense crust of lifeless cuticle, are feeding on the young green leaf,
the margin of safety is greatly narrowed and may wholly disap-
pear. The practical utility of this method of destroying insects in
any case, evidently depends on the existence and extent of this mar-
gin of safety.

The gasoline blast may, in fact, be used to kill any insect on any
plant. The time and method of use necessary to kill the insect will
vary widely for different kinds of insects and for the different states
and stages of each kind; and the time and method of use sufficient
to injure various kinds of plants will likewise differ widely accord-
ing to the kinds and condition of the plants themselves. The actual
effect of the blast on either insect or plant will also vary enormously
according to small details of the method by which it is applied.
They will vary, first, with variations in the pressure, which deter-
mines the extent and heat of the flame; second, with the distance
from the object at which the torch is held; third, with the rate of
movement at which the flame is passed over the surface treated;
fourth, with the temperature at the time and the amount and direc-
tion of the wind; fifth, with the direction of the blast, whether per-
pendicular or oblique to the surface; and sixth (not to specify
further), with the steadiness with which the flame is applied to a
given surface, whether held at one point for a definite time or
swayed back and forth over a considerable surface for a variable
number of times.

To determine the effect of all these different classes of variations
with sufficient exactness for practical guidance, and then to combine
all the various results of this inquiry with each other in a way
to form a system of practice which can be accurately described and
safely recommended for general use, is a task which no intelligent
investigator would enter upon lightly, or without such preliminary
tests as would enable him to judge whether any important result
was likely to come from more exact and extensive experiments.
The observations here reported are all in the nature of such pre-
liminary tests, made by different persons, each for his own satisfac-
tion, on different objects and in different parts of the country. They
are practical tests rather than complete scientific experiments, and

46

their value is hence suggestive rather than final. Those which have
to do with the San Jose scale, the harlequin cabbage-bug, and the
cotton boll-weevil are perhaps of the greatest interest, and will be
given first.

The San Jose Scale.—In the fall of 1897, Professor Pettit, of
Michigan, had five parallel burners fitted to an ordinary plumber’s
blast-lamp in such a way that a flame about ten inches wide could
be directed against the surface of a tree, and several trials of this
apparatus were made during the following winter on peach- and
pear-trees badly infested with the San Jose scale. ‘The heat pro-
duced by this lamp,” he says, “is very intense, and great care must
be observed not to allow the flame to remain at any one point long
enough to injure the tree. The best results were obtained when the
flame was steadily moved so that it covered a space of a yard in
length in from five to ten seconds. The results seemed to show that
the blast will kill the scale-insects with little or no injury to the
tree. ‘The trees were scorched in places where the flame had moved
too slowly, and the care necessary to avoid the scorching appears to
be the most serious drawback to the use of the blast lamp. In care-
less hands much injury may be done in a very short time, while
the skilful handling necessary for success would be rather expen-
sive under ordinary circumstances. Good judgment must be exer-
cised always, and the rapidity and effectiveness of the work will be
much modified by the temperature of the air, the direction and force
of the wind, the age of the trees, and the thickness of the incrusting
scales.”’ Referring to these statements in a recent letter, Professor
Pettit writes that he intended that the lamp should be used only in
connection with a spray, for burning off or loosening the outer lay-
ers of a crust of scales so that a fluid insecticide might penetrate to
those beneath. “I now realize,” he says, “that the same effects may
be obtained much more cheaply in other ways.”

By Professor Craig, of Cornell University, a torch much adver-
tised for the destruction of insects was used May 19, 1903, against
the San Jose scale on the apple, medlar, buffalo-berry, and dog-wood.
Different branches were flamed in various ways to ascertain the time
necessary to kill the scale and to determine the minimum exposure
to the flame of the torch which would kill the cambium layer of the
tree or shrub. In respect to time of exposure three methods of treat-
ment were used: passing the flame so rapidly over the surface that
it merely touched each point for an instant; moving it at the rate of
one foot per second; and holding it stationary on the infested spot
long enough to count one. The scales were reported to have been
killed in every case save one, in which a twig of dogwood had been

47

very rapidly flamed. ‘The general results,’ writes Professor Sling-
erland “were summarized as follows: First, the torch is impracticable
for large trees of apple, plum, pear, peach, or cherry, because of the
amount of time required to flame the whole tree. It would take a
man several hours thus to go over one large tree; second, there is
great danger of injuring buds or the cambium layer on thin-barked
trees; third, the torch might be used on small nursery stock or orna-
mental shrubs by an experienced operator who knew exactly what
time to expose the plant to the flame.”

Professor Phillips, of Virginia, made use, against the San Jose
scale, in 1903, of a torch sent by the manufacturing company for
trial to Professor Alwood, of that state. “March 28, of this year,”
he says: “I used this gasoline torch on two apple-trees four years of
age. ‘These trees were moderately infested with the San Jose
scale, and were treated by running the torch over the surface several
times. One tree was exposed to the torch about twice as long as
the other. ‘This treatment did not appear to injure the trees, neither
did it kill a perceptible number of insects.

“T was not satisfied with this trial, however, and detailed a stu-
dent assistant, Mr. E.. F. Cole, to test the torch, which he did August
7. ‘The tree treated was a four-year-old apple, badly crusted with
the San Jose scale. As it would be entirely impracticable to use this
torch against the San Jose scale during the summer, this treatment
was confined almost entirely to the trunks and main branches of this
tree, but in treating the tree in this manner, of course a few of the
leaves were also reached by the flame. The treatment was so severe
that the leaves on the treated portions of the tree were killed at
once, and when examined on August 20, portions of the bast tissues
of the bark were found injured also. Quite a large number of scale
insects were alive at that date.

“Judging from these two tests, | consider that the use of this
torch is quite tedious and impracticable, even on small trees. ‘ Be-
sides, such a small per cent. of the San Jose scales were destroyed
by it, even where the trees were seriously injured by its use, that I
do not consider it a practicable remedy.”’

Professor Symons, of Maryland, writes me that he personally
conducted some experiments with the same kind of a torch on dif<-
ferent varieties of peach and plum infested by the San Jose scale,
but that the results were not at all satisfactory. Although the insects
were dead two weeks later on the parts which had been hit by the
flame, young scales were crawling about over the surface in con-
siderable numbers, showing that it had been impossible to reach all
parts of the tree, especially at the ends of the branches. If used

48

when the tree was in leaf he could not avoid burning the foliage. As
a result of his experiments, Professor Symons concludes that it is
impracticable to control the San Jose scale with this torch.

To these observations by experts I may add a note of a trial of
the torch made by a practical gardener on some infested trees be-
longing to J. W. Stanton, of Richview, in this state. By oversight,
these trees were sprayed with whale-oil soap before they had been
critically examined as to the final effects of the blast on the San
Jose scale; but Mr. Stanton writes me that from what he could see
of the effects of the treatment at the time, he is of the opinion that
it would not be successful on tree fruits. One of my horticultural
inspectors, Mr. R. W. Braucher, happened, however, to examine
one of these trees after the treatment with the torch and before the
application of the whale-oil soap, and found that the bark was
scorched in some places, and that in others the scales were still
alive. :
From the foregoing experiments, it is clear that the gasoline
torch has at best only a very limited application in the treatment of
trees infested by the San Jose scale. It might be occasionally used
to advantage, as suggested by Professor Pettit, to burn off the outer
part of an unusually thick crust of scales on the trunk and largest
branches of a tree, preliminary to a treatment with the lime-and-
sulphur wash. As this insecticide does not penetrate readily to any
great depth, it is sometimes necessary to repeat a spraying after 2
time if the tree is too thickly incrusted. This second spraying might
perhaps be omitted if the torch were first used on the crust of scales.
It would be the merest folly, however, to think of using it as a sub-
stitute for an insecticide spray in the treatment of the San Jose scale,
or for any general treatment of orchard trees for any purpose what-
ever.

This torch was also tried on certain other orchard scales at Ur-
bana during the fall of 1902, but for reasons to be given presently
these tests are reported separately farther on.

The Harlequin Cabbage-bug.—The introduction of the use
of the gasoline torch against the harlequin cabbage-bug in the
South seems to be due to Mr. S. A. McHenry, recently superintend-
ent of one of the substations of the Texas Agricultural Experiment
Station. Indeed, Professor Sanderson, when official Entomologist of
that state, wrote me that, so far as he knew, Mr. McHenry was the
first man to make practical use of the blast torch against insects of
any kind. He is said to have used it successfully for several years,
as have others in his section of the state, but of late he has made

49

comparatively little use of it for that purpose because of the amount
of work required to go over a cabbage plant with the torch.

Professor J. M. Stedman, of Missouri, writes more confidently
of its usefulness against the cabbage-bug, saying, under date of
October 28, 1902, “I have not found the gasoline torch of any spe-
cial value as an insecticide apparatus except in extreme cases when
one has a sufficient number of the harlequin cabbage-bugs in his
cabbages to cause serious trouble. I have then used this torch to
good advantage. One can very readily pass over the cabbages fast
enough not to injure them, and at the same time to kill the harlequin
bugs. It is not necessary to have the bugs scorched sufficiently to
drop at once, as I have found that they will ultimately die if this
intense heat has been very rapidly applied.”

This cabbage-bug is not widely destructive in this state, although
it is continuously present in some parts of southern Illinois, and dur-
ing one season extended its injuries as far north as Champaign, and
was once found in Chicago by Mr. A. Bolter. The reported effec-
tiveness of this torch against this insect suggests the trial of it
against other bugs, which cannot be killed with arsenical poisons
since they do not eat the solid substance of their food plant but
merely suck its sap.

The Cotton Boll-weevil.—The appearance in Texas of the snout-
beetle known as the Mexican boll-weevil has caused general and jus-
tifiable alarm among the cotton-growers of the South, and the former
Texas State Entomologist, Professor Sanderson, has devoted him-
self to an assiduous study of the insect and has made many exper!-
ments for its destruction and control. This is indeed the most im-
portant, pressing, and perplexing problem which the economic en-
tomologist now has to deal with in the Southern States. In the
course of his work against this insect Profesor Sanderson has tried
two forms of the gasoline torch; one, a blast-lamp known as the
pear-burner, used in southwestern Texas for burning the thorns off
the prickly pear, and the other a torch sent him from Illinois by a
dealer who offers and advertises it for sale for the destruction of in-
sects. ‘The latter was found so faulty in construction that it could
not be used, and it was consequently returned. :

The pear-burner, which generates a much more powerful blast
than any of the smaller torches, was tried by Professor Sanderson
for burning up the squares of the boll-weevil as they lay upon the
ground, but so far, as he writes me October 28 of this year, he has
not had sufficient success with it to indicate that it has any value
for this purpose.

50

The only other beetles on which it has been tested by any of my
correspondents are certain unspecified species found on aster by
Professor Symons, of Maryland. “In this case,” he says, “‘it was
effective in killing the beetles, but one has to be so extremely carefui
not to hurt the flowers that I would hardly recommend it for prac-
tical use.”

Experiments at Urbana.—In response to my request, made
August 5, 1902, to the inventor and patentee of a modified form of
the gasoline torch intended especially for insecticide work, one of his
instruments was sent me with directions for its use, and was at
once put into the hands of my most experienced field assistant, Mr.
E.. S. G. Titus who, with the aid of another assistant, Mr. George I.
Reeves (both now assistants to the United States Entomologist),
tried it at various times during the following two months on such
kinds of injurious insects as could be found in any number at
Urbana at that time of the year. It was further tried on a fun-
gus parasite of the lilac leaf, and on various kinds of vegetation to
determine the effect on the plants of an exposure sufficient to kill the
insects infesting them. Although sent me expressly for experi-
mental purposes, this instrument proved to be relatively so weak in
action that its use by us should probably be regarded as a test of
the value of this kind of a torch rather than that of the torch
method in general; and it is on this account that I have kept our
own statements separate from those made to me by others, most of
whom seem to have worked with a more efficient apparatus.

The results of our various trials are here given as reported to
me by Mr. Titus at the close of his series of experiments, about
October 20.

“The torch is simply an ordinary ‘plumber’s torch’ fitted with a
two-gallon gasoline tank and a three-foot piece of rubber tubing.
A short iron discharge-pipe connects the rubber tubing with the
torch.

“Filled the tank about half full of gasoline according to direc-
tions. ‘The valve in this pump was of leather and by no means
circular in outline, and it was at first rather hard to secure even
pumping pressure. The connections were all very dry and needed
soaking. After an hour or so of work, cleaning the discharge-
pipe and burner, we were able to light the latter and get a flame.

“Under the heaviest pressure obtainable—sufficient to force
air bubbles from the pump valve and at the cut-off in the base of
the pump—the flame was tried at varying distances. At fifteen
inches from the burner the heat was scarcely sufficient to singe the
hair from the hand, but a little closer, ten to twelve inches distant,

ap

it would singe. The burner was used when running at full force.
The effects were about as follows, examinations being made at sev-
eral days’ intervals :—

“The trunk and smaller limbs of an apple-tree were thoroughly
treated. This tree was badly infested with Forbes and scurfy scales,
and also had on it considerable woolly aphis. The last-mentioned
insects were killed where they were completely burned off the limb;
but where only the woolly covering was burned off, and the insect
not actually caused to drop, there was little apparent injury. The
Forbes scale appears not to have been injured, except the young not
yet old enough to form a scale. The scurfy scale was not injured.
The smaller limbs were sufficiently treated to cause the bark to
blister in spots, without having any apparent effect on mature
scales of either kind.

“T have tried the burner under ordinary pressure at different
times against various other insects and foliage. A colony of fall
web-worms in a box-elder tree was treated, and a number of worms
that fell were placed in a cage in the insectary. These were given
plenty of fresh food, and did not appear to be inconvenienced by
the lack of hairs on their bodies. They grew, and some of them
pupated. Most of the remainder were parasitized, and the few that
died were full grown at death. The parasites emerged in due time
and were preserved.

“Arctian caterpillars (woolly bears) treated to the full force
of the burner for ten to fifteen seconds,.or even longer, had the
hair thoroughly singed from their bodies, and some were blistered.
The majority of these finished their growth and pupated. I could
see no greater mortality among them than ordinarily occurs with
this species under insectary conditions. Several cabbage-worms
were treated until they rolled from the leaves. Most of these were
not permanently injured, and those that died were burned so badly
that the outer skin was broken. To produce this effect upon a
caterpillar it must be treated with a direct blaze long enough to
cause the leaves to curl and blacken on the plants.

“Meadow moths (Crambus) flying about in the grass were
singed with the flame. Some of these would fly through the flame
so close to the burner that the hair on one’s hand would be quickly
singed off, but they were usually uninjured by this experience. To
kill one of these moths it had to be followed with the flame until
some parts were burned sufficiently to cause it to fall, when it could
of course be easily disposed of.

“Lilac leaves badly infested with mildew were thoroughly
treated, the burner being held at varying distances and acting for

De

varying periods of time. ‘The mildew does not seem to have been
affected where the leaves were not injured, and was rarely affected
where the leaves were burned sufficiently to cause them to curl
and later to wither. Leaves that were treated to the flame for three
seconds dropped off. Other leaves treated one second remained on
the bush and were not perceptibly injured. Between these two times
(which really represent flashing the burner over the surface and
holding it there for an instant) the leaves show varying injuries. At
first the mildew appeared to have been burned off, but specimens
which had been thoroughly treated and left in the insectary were
again covered with the mildew in five days.

“Elm, Osage orange, box-elder, apple, cherry, plum, grasses,
nasturtiums, cabbage, pine, cedar, Amorpha, walnut, rose-bushes,
peach, and several other trees and ornamental shrubs have been
treated at various times. I find that when the flame is held close
to the foliage for a few seconds this is visibly injured. If held a
short distance away the injury is not so great, but usually shows
after a few days by the blackening of the leaf or by the browning
and curling of the edges. Often leaves so treated will drop off.

“To sum up: The use of sufficient heat to destroy effectually
insect larve of the kinds we treated, will injure the foliage and often
the twigs.”

Mention may be made of a trial of the torch by Mr. Mally, in
Ohio in 1808, the details of which can not now be given because
the record is not accessible. This torch, obtained from Illinois, was
put into Mr. Mally’s hands by Professor F. M. Webster, with in-
structions to give it a thorough test. It was taken by Mr. Mally
on one of his field trips, used on a variety of insects, including the
chinch-bug, and returned with the general report that it was un-
satisfactory for its purpose.

UsE OF THE GASOLINE TORCH AGAINST THE CHINCH-BUG.

Notwithstanding the generally unfavorable character of the
statements made to me concerning this torch by those best able to
judge of its value, it seems that it may have a field of usefulness
for the destruction of certain kinds of injurious insects. Thinking
that it might profitably be tried in comparison with other aids to
the trap and barrier method for the destruction of chinch-bugs as
they come out of small grain in midsummer, I provided for a series
of field trials with a first-class torch, in connection with other experi-
ments on the chinch-bug made during the summer of 1904. To
make sure of having a good example of this form of blast-lamp, one

53

was bought from the manufacturer in person, who was kind enough
to give careful instructions and to illustrate personally its use in the
field.

Two miles south of Carbondale was a field of forty acres of corn
adjoining wheat infested by chinch-bugs, which had almost com-
pletely destroyed the corn on an area two hundred and twenty yards
long and seventy yards in depth. Only a few scattering hills re-
mained on this strip, and a good deal of this was lying almost flat
on the ground. Farther within the field the corn was only moder-
ately infested, but was of course still liable to serious injury by the
invading host. July 30, when this experiment began, most of the
bugs had developed wings, though many were still to be found in
all stages from the very young to the lately transformed adult.

The lamp was first used on fallen hills thickly covered with the
bugs, many of which, however, were concealed within leaves closely
rolled for their entire length. When the blast of flame was turned
upon the corn, many bugs exposed on the surface of the plants fell to
the ground, where they could easily be killed by following them with
the flame. Many others, however, would not leave their shelter
among the leaves, and these were left uninjured.

Where the field was only moderately infested, scattered adults
and clusters of them exposed to the flame dropped to the ground
at once, where they could be quickly destroyed; but many dropped
from the side of the hill farthest from the torch, where they could
not be reached until the operator returned down the other side of
the row, as only one side of the hill could be treated at once. Indeed,
for a satisfactory application of this method it would be necessary
that two men should take a row together, one on each side, operat-
ing against each hill simultaneously. Even this would not wholly
prevent the premature escape of the bugs, as many fell from the
corn two or three hills in advance of the roaring blast and hurried
away in an effort to escape. ‘Those which remained secreted behind
the ensheathing bases of the leaves were also, of course, protected
from injury. In this respect the blast-lamp proved less efficient than
the kerosene emulsion, since the latter was especially useful in
reaching the accumulations of chinch-bugs hidden behind the leaves.

For a more accurate test of the effect of the hot blast ten cages
were arranged in such a way that the bugs could be treated within
them and held captive under normal conditions for observation after-
wards. In one of these cages two hundred and fifty chinch-bugs,
mainly adults, were flamed with the exit of the blast held for one
second an inch from the bugs, the pressure having been pumped up
about to a maximum by two hundred strokes of the piston. The

d4

following day eighty per cent. of the bugs were dead, together with
several adult blister-beetles (Epicauta marginata) and Colorado po-
tato-beetles treated at the same time.

In another test like the preceding, except that the bugs were ex-
posed to the blast for two seconds, eighty per cent. were dead the
following day. A third experiment duplicated the first with a result
to kill eighty-five per cent. of the bugs. In a fourth cage the flame
was held for a second two inches from the bugs, and the following
day seventy-five per cent. of the two hundred and fifty treated were
found to have been killed. At a distance of four inches the flame
killed but ten per cent., the remainder crawling about, apparently
uninjured, twenty-four hours later. An adult potato-beetle and two
larve of the same, a common cabbage-worm, and a caterpillar of
the cabbage Plusia were likewise uninjured by this treatment. In
another experiment it was shown that if the burner were held three
seconds at a distance of four inches from the insects, only ten per
cent. of the chinch-bugs were killed.

A thousand chinch-bugs were next exposed to a gentle blast of
the gasoline flame until they were all unable to crawl. On the fol-
lowing day about fifty of them were still able to move, although the
legs and other appendages of some of these were scorched.

In order to ascertain whether the bugs might die from the after-
effects of the blast, a thousand specimens in another cage were sub-
jected to an extreme scorching heat without killing them at the time.
On the following day at least half of them crawled away, evidently
uninjured. Another lot of a thousand were flamed until a third
were killed outright, the remainder being rapidly flamed several
times but left able to crawl away. On the following day at least
two thirds of the bugs were alive. From these experiments it ap-
pears that bugs not killed at the time of treatment do not ordinarily
die thereafter. A lot of two thousand chinch-bugs or more, col-
lected from corn and confined in a similar cage, which were kept as
a check during the course of these experiments, lived with less than
one per cent. of loss, and these were probably injured in collecting.

To determine the resisting power of the corn to the hot blast
of the gasoline torch several plats, equally infested and all in one
field, were treated variously. ‘The flame was moved over the plants
sometimes quickly, sometimes slowly, and was sometimes held
close to the leaves, sometimes at a greater distance. In this experi-
ment the unit was a plat of a hundred hills of corn, which averaged
three feet high at the time. All plats were treated in the afternoon
of July 30, the weather being clear and hot, with a little wind. The
lamp was used at a high pressure, produced by two hundred suc-

5)5)

cessive strokes of the pump. The heat was sufficient to scorch the
hairs from the back of the hand at twelve inches from the burner,
and to burn in two in thirty seconds a stalk of corn held four inches
from the nozzle.

In the first plat the flame was passed steadily upward for a foot
along the stalk at the rate of about two feet per second, this flaming
process being four times repeated for each side of the hill with the
nozzle held an inch or less from the plant. Each plant was thus
exposed to the blast for four seconds in all, a half a second each
time. ‘Two days later some of the bugs were dead, but many were
still alive, and many stalks of corn were seriously injured, scarcely
a hill in the plat having wholly escaped scorching. In some hills
the large leaves were burned, and in nearly all the lowest leaves were
visibly scorched.

This experiment was repeated on another plat except that the
tube was held about four inches from the plants. Two days later
the corn was less injured than in plat one, but nearly all was scorched
more or less, especially the upper leaves. Some of the bugs were
still alive, probably those which fell to the ground and escaped and
those secluded beneath the sheaths of the leaves.

In another plat the treatment was varied by flaming the bugs
at the base of the plant as they fell upon the ground, using on an
average two seconds additional for each hill. The torch was handled
about as in the first experiment, and the plants were similarly in-
jured. The hardened cuticle at the base of the stalk was less likely
to be scorched than the green and tender leaves. The bugs were
nearly all destroyed on this plant, although a few were still alive the
following day.

By other experiments it was found that by two or three treat-
ments, separated by intervals sufficient to allow the escaping bugs
to collect again, the corn might be almost completely cleared of
bugs, but, unfortunately, without the most painstaking care injury
to the plants was such as to make this form of treatment quite in-
admissible.

The cost of these operations was considerably less than the cor-
responding treatment with kerosene emulsion. The time required _
was practically the same, but the cost per acre was thirty-four cents
for the emulsion and fifteen cents for the gasoline.

It was Mr. Taylor’s judgment that two treatments with a four
per cent. emulsion would have about the same effect upon the bugs
as three applications of the torch, but the latter is more convenient
to use, requiring no previous preparation of the fluid and no hauling

of water to the field. The risk of injury to the corn is of course
5

06

much greater with the torch—especially in the hands of unskilled or
careless workmen. ‘The price of $10 charged for the blast-lamp
would determine the choice of many, since apparatus may be wholly
dispensed with in the preparation and application of the kerosene
emulsion.

There is an evident use for the gasoline torch in the destruc-
tion of bugs collecting either in the dusty furrow or along the coal-
tar line, where these are used as barriers against the movement of
the chinch-bugs from small grain to corn. By directing the hot
blast against the insects trapped in the furrow or collecting along
the tar line on the ground, these could be rapidly killed at smail
expense, and the post-hole traps might thus be dispensed with.
Care would be necessary, however, to prevent the burning or drying
of the tar by the flame.

It also seems quite probable that a fine spray of pure kerosene,
or even of crude petroleum, might be used to good advantage for the
destruction of the chinch-bugs on the ground, and perhaps at less
expense. On the coal-tar line the kerosene might be preferred be-
cause it would tend to soften the tar and lengthen the period of its
efficiency as a barrier, and could not dry and harden it as would the
flame. Opportunity was wanting last season for experiment cover-
ing these last suggested points, and they must consequently be tested
at some other time.

At a later date the blast-lamp was used in the potato field to de-
stroy the adults and larve of the common potato-beetle. For this
operation it was found entirely impracticable. The insects could
of course be killed, but at an expense of about fifteen hours of labor
per acre.

GENERAL SUMMARY.

These experiments may be considered as a test of the efficiency
of barriers constructed to arrest the movement of chinch-bugs in
passing from small grain to corn at harvest-time, under conditions
unfavorable to success, that is, when the chinch-bugs were not so
numerous as rapidly to destroy the wheat—compelling their migra-
tion en masse—and when the weather was neither extremely hot
nor very dry. The spring and early summer of 1904 proved to be
unusually wet, and chinch-bugs consequently were not generally
abundant enough to threaten any great injury to corn. The weather
also prevented the use of the dusty furrow, most commonly resorted
to as a barrier to the movements of chinch-bugs, and compelled a
reliance on the coal-tar line with post-hole traps instead. So far as
the season permitted a real test of the operation, it was completely

57

effective for the protection of corn, and there is no doubt that it
would have been equally so if chinch-bugs had been ten or a hun-
dred times as numerous.

A partial failure of the experiment due to the character of the
weather of the season did not diminish its value as a means of de-
termining the cost of an effective operation on the scale of actual
farm practice. It was demonstrated that the coal-tar strip may be
laid down and maintained for four weeks—the maximum period
necessary—at a cost of $22 a mile, with the effect to trap all bugs
approaching the line, where they may be readily and rapidly killed.
The average cost of making a dusty furrow or ditch sufficient to ar-
rest and trap all chinch-bugs attempting to cross it was approxi-
mately three cents a rod, or $10 a mile, for labor only, no materials
being required. This furrow can not be used, however, except in
dry hot weather.

Various methods of preparing the ground for the coal-tar line
were used in comparison. One of the most satisfactory methods was
that of plowing a back furrow in the stubble near the edge of the
field, and packing this with a roller or beating it flat and hard with
spades. A strip of sod may be prepared to receive the line by scrap-
ing away the grassy surface with an ordinary farm scraper, after-
wards leveling and smoothing it carefully with a shovel or hoe.

A kerosene emulsion prepared by mixing two parts of kerosene
and one of soap-suds by violently beating with a stick for about five
minutes, and diluting to contain four per cent. of kerosene, was found
efficient for the destruction of all the chinch-bugs touched by it, and
was successfully used for clearing rows of corn along the borders
of a field which had become infested for lack of effective barriers.
Stronger kerosene mixtures made in this way commonly proved in-
jurious to the plant. A barrel of diluted emulsion costs about thirty-
four cents. It was applied to the corn by hand at an average rate
of a barrel an acre—five acres per day for each man. A solution
of whale-oil soap, one half pound to the gallon of water, proved to
be a safe and sufficient insecticide for corn-field use. Its cost was
$1.12 a barrel.

The gasoline blast-lamp, tested on a great variety of insects,
was found to be only occasionally useful. By two or three suc- —
cessive treatments separated by intervals sufficient to allow the
chinch-bugs which escape to collect upon the plant, badly infested
corn might be almost completely cleared of bugs, but serious injury
to the corn itself was almost certain unless the most painstaking care
was used. The cost of material is less than that of kerosene, amount-
ing to only about fifteen cents an acre for each treatment with the

58

former and thirty-four cents for the latter. Three applications
with the torch were about equal to two treatments with the kero-
sene emulsion, the first being most convenient to use but also most
dangerous to the plant. It is suggested that this gasoline torch may
be found a convenient apparatus for destroying chinch-bugs collect-
ing either in the dusty furrow or along the coal-tar line, when these
are used as barriers.

COMPARATIVE EXPERIMENTS WITH VARIOUS INSEC-
TICIDES FOR THE SAN JOSE SCALE.

In my Eleventh Report as State Entomologist, published in
1903, I gave the results of experiments and extensive practical opera-
tions with several of the more prominent insecticides used against the
San Jose scale,* including whale-oil soap solution, hydrocyanic acid
gas, kerosene emulsion, mechanical mixtures of kerosene, and lime
and sulphur compounds known as the “California wash’ when made
with the addition of salt, and the “Oregon wash” when made
with blue vitriol. All these substances have been found effective
against the San Jose scale, but the kerosene mixtures and emulsions
were abandoned by me in December, 1901, because of serious dam-
age done to trees with these insecticides in 1900 by one of my spray-
ing parties, working under the immediate personal charge of my
most experienced operator.t Crude petroleum, much used in some
other states, has been little used at any time in Illinois, and observa-
tions made by one of my assistants in 1902 in the Catawba Island
district in northern Ohio, where it had been extensively applied by
orchardists, were so discouraging that I have made but a single ex-
periment with it./: | 4

After the passage of the Lllinois inspection law in 1899 it be-
came my duty to treat, free of expense to the owner, all orchards in-
fested by the San Jose scale which there was good reason to believe
had become so infested before the passage of that act. As it has
now become virtually impossible to trace existing infestations to so
remote a beginning, this feature of our law has become practically
inoperative, and the owner is required to treat infested trees on his
own account. ‘This fact has made it important that every effort
should be made to distinguish, among the various available insecti-
cides, those which are at the same time effective, cheap, and conve-
nient of preparation and application, especially as several commercial
compounds of lime and sulphur, and others with a kerosene basis,
are being extensively advertised and offered in condition for immedi-

*Twenty-second Rep. State Ent. Ill., pp. 56-57, 89-90; Bull. 80, Ill. Agr. Exper. Sta-
tion, pp. 492-493.

+Twenty-second Rep. State Ent. pp. 48-50.

tIbid., pp. 93-95.

243

60

ate application when diluted. I consequently, last winter, instructed
Mr. E. P. Taylor, the assistant in charge of orchard inspection and
insecticide operations, to carry on a series of experiments in-a care-
fully chosen orchard, intended to test a number of these insecticides
under identical conditions and in a way to enable us to give the re-
sults in the exact form of percentages of benefit for each.

For this purpose, control was obtained of two small orchards
near Richview, Ill., both belonging to Mr. Edward Tucker, one con-
taining 780 apple- and peach-trees badly infested in the main, and the
other, 680 peach-trees infested throughout but much less heavily so.
These orchards were divided into plots of varying size, those in-
tended for the more important insecticides containing from 47 to 141
trees each. Minor experiments were made on smaller lots, of from
3 to 33 trees, and single trees here and there were also used for a
few preliminary tests.

Insecticides were applied, partly early in January, a the 3d
to the 1oth, and partly from the 21st to the 24th of March, 1905.
‘Twenty-seven kinds and forms of insecticides were used in all, of
which seventeen were various compounds of sulphur and lime, six
were kerosene preparations, three were soap solutions, and one was a
simple alkali. The results were tested by three critical examinations,
one made January 3 and 4, a second during the last days of May, and
the last September 5 to 8. It is of course impossible to get an accu-
rate idea of the effects of the treatment by comparing the ratio of
living to dead at the time of the treatment with the corresponding
ratio at a considerable interval thereafter, unless the scales remain
attached to the tree after death; and that they gradually disappear,
especially after a lime and sulphur treatment, was shown by observa-
tions reported by me in 1902.*

SySTEM OF INSPECTION.

The choice of a system of inspection by which the condition of
trees treated with various insecticides could be compared with their
condition before treatment, and with that of other trees not treated
but reserved as checks, was a difficult and perplexing matter. At
first | was disposed to depend mainly on counts of dead and living
scales from various parts of carefully selected trees, from which
average ratios of dead to living, before and after treatment, might
be coripited, but such comparisons rapidly become misleading as.
the scales killed by the spray disappear under exposure to the
weather. Comparisons of the results of treatment with different in-
secticides can not be reliable if based on counts of living and dead,

*Bull. Ill. Agr. Exper. Station, No. 71, p. 243.

61

because the scales killed by one insecticide may remain longer at-
tached to the bark than those killed by another, and there is abundant
evidence that this is often the case. It is furthermore practically
impossible to make sure that a tree selected for a scale-count is a
fair average of its plot with respect to the degree of its infestation,
and scarcely less difficult to make sure that the parts of its infested
surface selected for counting are a fair average for the tree. For
these reasons the counting method was abandoned, in the main, and
I have relied instead upon a careful estimate of degrees of infesta-
tion for each tree of both check and experimental plots, these esti-
mates being recorded in figures ranging from I to 6. From these
the average degrees of infestation for the trees of each plot were fig-
ured, and these averages were compared with each other in a way
to show numerically the effect of the treatment in a reduction of the
average amount of infestation.

ConpITIons NECESSARY TO EXAct EXPERIMENT.

In order to an estimate of the precise value of the results here
reported, it will be helpful to review the conditions necessary to an
entirely satisfactory experiment of this description. In the first
place one should have at his command an orchard of considerable
size, either all of one variety or with the separate varieties planted
in complete and continuous rows all running in one direction. This
should be divided across its whole width, and across the variety
rows, into strips of five rows each if moderately infested by the San
Jose scale, and into seven to ten rows if heavily infested, each strip
receiving a different treatment except that occasionally strips should
be left untreated as checks. To avoid the mutual influence of check
and experimental plots upon each other, which may extend from one
to three rows in each direction across the boundary, only the interior
rows of each strip should be used for comparison. Experimental
trees near the borders of the check strip are likely to receive young
scales from the latter in larger number than they lose, if the experi-
mental treatment has had any marked effect, and the reverse is of
course true of the marginal rows of the check. This is not a theoret-
ical supposition merely, but is shown by our previous experience,
and by some of the averages to be reported farthet on. As the check
plots will act as centers of general dispersal of the scale insects
during the whole of the following season, there should be no more
of them than are clearly necessary. One at each end of the orchard
will usually be enough. ,

The trees of the interior rows of each strip should be graded very

62

carefully, one by one, as to the degree of their infestation, using,
for convenience, a scale of ten degrees. One such grading should be
made and recorded at the time the trees are sprayed, another about
the last of May, just as the young are beginning to appear, and a
third at the end of fall, when multiplication of the scales has vir-
tually ceased for the season. All the grading should be done by
one person, or by two persons independently, their estimates being
averaged, and the person grading the infestation should not know
the particulars of the experimental treatment.

A comparison of the average degrees of infestation of the checks
when the spray is applied, and again in May, will show the extent
to which the scales may have died during the interval, under the
effects of weather or from other causes, and a comparison of the check
and experimental plots, respectively, in May, will show the immedi-
ate effect of the insecticide. A similar comparison of these two
kinds of plots, made at the end of the season of multiplication, will
show the ultimate effect of the treatment at the end of the year.

ORIGINAL PURPOSE OF OPERATIONS.

Our own operations were originally planned with special refer-
ence to the comparative values of modifications of the lime and sul-
phur mixtures proposed by various entomologists, and also as a
preliminary test of the efficiency of soluble petroleums, lime and sul-
phur solutions, and other ready-made commercial products fre-
quently offered for sale. Reports made by my field parties of the
partial failure of midwinter sprayings with the lime and sulphur
washes led me also to provide for a careful test of the final effect of
sprays applied in January as compared with those applied in March.

Most GENERAL RESULTS.

The main general outcome of these experiments was to establish
still more firmly the lime and sulphur washes as superior, on the
whole, to all the other mixtures tested, and to show that January
applications of these preparations have scarcely more than half the
final effect of applications made in March. Among the lime and sul-
phur mixtures, those made without salt or blue vitriol seemed clearly
more efficient, as insecticides, than the older forms containing those
substances, and the solutions made with soda, without boiling, were
the least efficient of all.

63

THE LIME AND SULPHUR MIXTURES.

Seventeen preparations with a lime and sulphur basis were used
in these experiments. They included various forms of the “Cali-
fornia wash” and the “Oregon wash,” and mixtures of lime and sul-
phur without the salt necessary to the former or the blue vitriol neces-
sary to the latter. These preparations varied in the kind of lime
used in making them, in the proportions of the various ingredients,
and in the length of time during which the mixtures were boiled to
procure the solution. ‘Two compounds purporting to be ready-made
solutions of lime and sulphur were used, known respectively as “Cal-
cothion” and ‘Con Sol.”

Major Experiments.—Eleven of these experiments, in which
more than 50 trees were treated, will be reported first, in the order
of their final effectiveness.

1. This was a lime and sulphur wash made of 15 pounds of Mar-
blehead lump-lime and an equal weight of sulphur to 50 gallons of
water. The sulphur was first put into 12 gallons of water nearly at
the boiling point, after being mixed with enough water to form a
thin paste. ‘The lime was then added and the mixture was boiled for
40 minutes with the necessary stirring. The whole was strained
into a 50-gallon tank which was then filled with water.

Fifty-one trees were treated March 22, 1905, in the less-infested
orchard (Orchard I1.), at a sufficient distance from the check strip
to prevent any possible spread of the young scales to the experi-
mental plot. The trees on this plot were compared September 10
with those in the two central rows of the check plot—which was six
rows wide—both being carefully graded as to degree of infestation
according to the system already described. ‘The check trees aver-
aged at this time 5.6 degrees of infestation, estimated on a scale of
six degrees. ‘Those of the experimental plot, on the other hand,
averaged 1.2 degrees—a difference of 4.4 degrees in favor of the
experimental plot, or a ratio of benefit of 79 per cent.* In other
words, the number of living San Jose scales on this experimental
plot was virtually one fifth that which would have been present Sep-
tember 10 if no treatment had been applied.

Finally, if we compare the condition of this experimental plot
September ro with the condition of the same plot January 3, when
the trees were first inspected, we find that the September infestation
averages just one half that of January.

2. This was also a lime and sulphur mixture, differing from the

*To ascertain this ratio, the figures denoting the infestation of. the experimental
plot are subtracted from those of the check plot, giving 4.4 per cent, as the difference,
and this divided by 5.6, the measure of infestation of the check trees, gives 79 per cent.

64

preceding especially in the fact that 21 pounds of lime and 18
pounds of sulphur were used to 50 gallons of water. The method
of preparation was virtually the same.

Sixty-six trees, in four rows running across the end of the less-
infested orchard, II., were treated March 22 with one hundred gai-
lons of the spray. Ata general inspection made May 27, this plot
was reported as in favorable condition, with very few living scales,
and none of them young. Examined September 10, the average in-
festation was figured at 1.36 degrees, which, compared with the infes-
tation of the two central rows of the check plot, gives a benefit of
76 per cent. as a consequence of the treatment. Compared with its
own average infestation of the preceding January, we find this plot
improved about 44 per cent.; that is to say, the degree of September
infestation is approximately 56 per cent. that of the preceding Janu-
ary. In the check plot, with which this is to be compared, the Sep-
tember infestation was nearly two and a half times that of January.

3. This is a simple lime and sulphur mixture like No. 1 of this
series, the ingredients being in the same proportions of 15 pounds
each of lime and sulphur to 50 gallons of water, and differing merely
in the method of preparation. In this, the lime was first slaked in
10 gallons of water where 50 gallons of the spray were to be pre-
pared, the sulphur was then stirred in dry, and the whole was cooked
from 30 to 40 minutes.

One hundred and one trees of Orchard II. were sprayed March
22 with one hundred and forty gallons of the solution. As this plot ot
six rows, running the whole width of the orchard, lay immediately
beside the check, the average September infestation of the two
rows adjoining the check was notably greater than that of the re-
maining four rows. For the first two rows it averaged 1.9 degrees,
and for the remaining four rows, I.44—an excess of 32 per cent. of
infestation, apparently due to the proximity of the check and the
consequent spread of the young from those heavily infested trees.
On this account the two inner rows of 17 trees each were rejected,
and the four rows remaining were compared with the two central
rows of the check plot itself.

Comparing the 1.44 degrees of infestation of the experimental
trees with the 5.6 of the rows used as checks, we have a benefit of 74
per cent. resulting from the treatment. Or, if we choose to compare
the September condition of the plot with that of January—again
omitting the rows nearest the check—we find a difference of 38 per
cent. in favor of the September condition.

4. This was the so-called “California wash,’ containing 15
pounds each of lime, sulphur, and salt, to 50 gallons of water.

65

Thirty pounds of sulphur was first stirred into 20 gallons of boiling
water, and 30 pounds of lime was added. The mixture was then
boiled for thirty minutes, with constant stirring, after which 30
pounds of salt was added and the boiling was continued for 15 min-
utes more. ‘The mixture was then diluted with water to form one
hundred gallons, and applied March 21 to 66 trees of Orchard II..
standing in four rows at a considerable distance from the check.

Examined May 29, this plot was reported to be in excellent con-
dition, with but few living old scales and scarcely any young. Of
100 scales taken at random, 15 were alive—a ratio which, however,
would have but little significance, two months having elapsed since
the trees were sprayed. Ona visit to these trees made September Io,
this plot showed an average of 1.8 degrees of infestation, cor-
responding to a benefit of 68 per cent. as compared with the condi-
tion of the check at the time. If the comparison be made with
the January condition of the same plot, the September condition
shows a gain of 37 per cent.

5. This, like the preceding number, is a “California wash,” but
with 21 pounds of lime, 18 pounds of sulphur, and 5 pounds of salt,
to 50 gallons of water. It was prepared, like the preceding mixture,
by pouring the sulphur into the water first, and following with the
lime.

It was applied March 22 to 49 trees standing in three rows of
Orchard II., seven rows intervening between this plot and the check.
May 29, scattering full-grown females were seen, but young were
extremely few. Only 7 were found on 5 trees. The bark was still
covered with an even whitish coat at this date—two months after
spraying. Of 148 scales examined, 20 were alive. On September 10
the average infestation was estimated at 1.9 degrees, which, com-
pared with the check rows, gave a benefit ratio of 67 per cent. That
is, the scales alive on these trees were approximately one third the
number which the trees would have borne if they had not been
treated the preceding March. Compared with the January esti-
mate, the September infestation was about 25 per cent. less. In
other words, the effect of the spray up to this time had been to
counterbalance the increase of the scale by multiplication, and to re-
duce the original number by one fourth.

6. The usual “California wash,’ made with 15 pounds each of
lime, sulphur, and salt, to 50 gallons of water, the lime being first
slaked, and the sulphur added in the form of a paste. The mixture
was then boiled for 30 minutes, and the salt was added and the
whole boiled 15 minutes more.

Sixty-eight trees of Orchard II. were treated March 21. They

66

were in four rows running across the orchard near one end, and far

removed from the check. May 29 a few old living scales were found

on half a dozen trees, but no young, either crawling or newly set.

The bark of some of these trees was still covered with innumerable |
dead scales. September 10 the scales remaining had multiplied

somewhat, giving an average infestation of 2. degrees, and showing
a benefit of 64 per cent. Compared with the condition of the trees

in January, at which time the infestation was estimated at 33 per

cent. per tree, the September condition showed an improvement of

38 per cent.

7. These trees, unlike all the preceding, were in the orchard
originally the worse infested of the two (Orchard I.), its check plot
averaging, in January, 3.3 degrees of infestation when that of the
other orchard (II.) averaged 2.2 degrees. At the time of the Sep-
tember inspection, however, this difference had more than disap-
peared, the infestation of these two orchards being now 4.94 for
Orchard I. and 5.36 for Orchard II. That is to say, the infestation
of the orchard worse infested in January had increased by 49 per
cent. while that of the less-infested had increased by 145 per cent.
The reasons for this difference were not clear. ‘The September infes-
tation of the check plot in Orchard I. was practically uniform, show-
ing no invasion from the adjoining plots, and I have used, for com-
parison, the averages for the whole of it instead of those for the
two central rows only, as in Orchard II.

This experiment was a January treatment of 141 trees, some
peach and some apple, with the “Oregon wash” made of 15 pounds
each of lime and sulphur, and 14 pounds of blue vitriol, to 50 gal-
lons of water. Two hundred gallons of the wash were used Janu-
ary 3 and twelve gallons more the following day. The temperature
of January 3 was but a few degrees from freezing, part of the time
above and part of the time below. The ground was covered with
snow, and light winds blew from the north and northwest. Janu-
ary 4 the temperature fell nearly to zero, and the wind shifted to
the south.

The solution was prepared by the process commonly used in
all our recent orchard work, the lime being first placed in water
which had been heated to the boiling point, and the sulphur paste in-
troduced while the lime was slaking. The mixture was boiled for
30 to 40 minutes, and the blue vitriol, previously dissolved, was
added and the whole boiled for 5 minutes more. All of the trees
were thoroughly sprayed, and but few tips of twigs or patches of
bark could be found not covered by the residue after the fluid had

67

evaporated. During the colder part of these days the spray froze
as soon as it touched the bark.

May 26, 964 scales were examined, of which 773 were dead, and
IQI, or 20 per cent., alive. May 29 a general inspection of this plot
showed many living scales, young and old, both decidedly more abun-
dant on the apple than on the peach. Fifty young, for example,
were found in one square inch of the under surface of a twig two
inches in diameter, and on another equal area 110 were counted.
Traces of the winter spray were still visible on the trees. Septem-
ber 5 the average infestation was estimated at 2.4 degrees, which,
compared with the 4.94 of the check plot for this orchard, gave a
benefit ratio of 51 per cent. If the September condition of these
trees is compared with that of January, a gain of 23 per cent. is
found.

8. This is a companion experiment to No. 6, the same prepara-
tion being used, in the previous case in March and in this case in
January. It was the usual “California wash” of 15 pounds each of
lime, sulphur, and salt, to 50 gallons of water. It was sprayed Jan-
uary 10 upon three rows of peaches, 47 trees in all, in Orchard II.—
a plot immediately beside No. 6. The temperature ranged from
10° to 12° above zero, and snow was falling, with a northeast wind.
The spray froze as it struck the trees.

At the inspection of the 29th of May this plot was reported as in
very unfavorable condition, many young scales being found on 4
trees examined. September to the infestation of this plot averaged
3.1 degrees—to be compared with 5.6 of the check plot of its or-
chard. This gives a benefit of 45 per cent. as compared with the
September check, or of 12.5 per cent. if compared with its own
January condition.

9. This is an experiment with the “Oregon wash,’ 20 pounds
of lime, 15 pounds of sulphur, and 114 pounds of blue vitriol, to
50 gallons of water. It was applied to a plot of eight rows in Or-
chard I. containing 126 trees, only five rows of which, containing
78 trees, were used for comparison, owing to an apparent contami-
nation of three rows from the check plot adjoining. These trees
were sprayed January 3 to 5, the temperature ranging from 28° to
36°. ‘Two hundred and sixty-two gallons were used, the most of it.
January 4.

One thousand and ten scales taken at random from 12 trees were
examined in this orchard May 27, and 26 per cent. were found alive.
Generally speaking, however, the condition of the orchard was re-
ported as extremely favorable. Most of the insects found were on
the higher twigs, which were less heavily coated, with the residue

9)

68

of the spray than were the larger branches and the trunk, and the
ereater part of the living scales were found on such twigs. They
were, as before, more abundant on the apple than on the peach.
September 5 the average infestation of the 78 trees available for
comparison was figured at 2.9 degrees, which, compared with the
4.9 of the check plot, gives a benefit of 42 per cent. from this Janu-
ary treatment with the “Oregon wash.’ As compared with its
own January condition, this plot had been improved by 12 per cent.

10. A January spray of a lime and sulphur mixture made with
soda—30 pounds of lime, 15 of sulphur, and 5 of soda, to 50 gallons
of water. The mixture was prepared January 4 as follows:

Thirty pounds of Marblehead lime was slaked in 12 gallons of
water, the sulphur being added in the form of a paste during the
slaking process. ‘The soda was added in three lots, the first about
5 minutes after the lime began to slake, and the 28S at intervals
of 2 or 3 minutes. The mixture was then stirred for 10 minutes,
diluted with cold water to make 50 gallons, no boiling being neces-
sary, and applied to 127 trees in Orchard I.—a plot of eight rows
immediately beside the check. ‘The temperature was a little above
or a little below freezing, a strong wind blowing from the south.
There was no appearance of any increased infestation on the side
nearest the check plot, and the averages for all these rows are conse-
quently used for comparison.

May 27, scales were quite numerous on this plot, including both
well-grown females and some young. Of 676 examined, 30 per
cent. were found alive. On the check plot at the same time, of 1200
scales examined, 39 per cent. were alive. September 5, when the in-
festation of this plot was finally graded, it was found to average
3.37 degrees, less by some 23 per cent. than the infestation of the
check plot in this orchard. Compared with its own January condi-
tion, the September infestation was estimated at practically 15 per
cent. less.

11. This, like the preceding, is a lime, sulphur, and soda mix-
ture, differing in the smaller proportions of lime and sulphur and in
the greater amount of soda. Sixteen pounds of lime and 8 each of
sulphur and soda were used to 50 gallons of water. In the prepara-
tion of this solution 8 pounds of sulphur paste was put into a few
gallons of boiling-hot water, 8 pounds of caustic soda was added
to this and stirred until the sulphur was dissolved, and 16 pounds
of lump-lime was then put in and stirred until completely slaked.
The entire process required about 15 minutes’ work.

The spray was applied January 5 in Orchard I. to 124 trees,
about equally peach and apple, the temperature varying from 32° to

69

54° at different times of the day. The plot of eight rows was at the
end of the orchard and consequently well removed from the check.

May 27, these trees were found unusually infested as compared
with others treated at the time. Of 575 scales examined, 159 were
living—a ratio of 28 per cent. At the fall inspection, September 5,
the average infestation of this plot was rated at 3.43, giving a bene-
fit of 19 per cent. for the treatment if compared with the check, or
about 12 per cent. if compared with its own January condition.

The principal data of the foregoing discussion may be conveni-
ently summarized, for further consideration, in the first of the fol-
lowing tables.

I. TABLE OF EXPERIMENTS WITH LIME AND SULPHUR PREPARATIONS

ON PLOTS OF 47 TO 141 TREES.
(Arranged in order of benefit from treatment.)

Sept. :
Sept. |pene.Cost
ixper.| Insecticide —|charg/Trees|Treated| sation | St | Yoo
Degrees Aeon Gals.
Check Plot I 126 4.94
Check Rows IL 34 5.6
1 |Lime and Sulphur*
15 L.. 15 8., 50 W. as 51 | Mar. 22 1.2 79 |$ .84
> |Lime and Sulphur
21 L.,18 S.,50 W. He 66 og pee 1.36 76 | 1.03
3 |Lime and Sulphurt
15 L., 15 S., 50 W. ue 67 rs a a 1.44 74 .84
4 |California wash*
15 L., 15S.,
15 salt, 50 W. ae 66 Coe 1.8 68 94
5 |California wash
210 NSS... |
5 salt, 50 W. bt COV Wir 1.9 67 1.07
6 |California washf
US Ip, AlGrs¥e |
15 salt, 50 W. se 68 uC ait 2. 64 94
7 |Oregon wash
TD Ips WES,
1.5 B. V.,.00 W: I 141 | Jan. 3 2.4 Slik
8 |California wash |
TEV ese basioe
15 salt, 50 W. Il 47 rf 10) 3.1 45 94
9 |Oregon wash
PUES DSS Wis Be
LSBs Ve;,.00) W. I 78 | Jan. 3-5 rae) Ae | OM
10 |Lime,Sulphurand Soda
30 G5, 15:S.,
5 soda, 50 W. cs 127 be. 3.37 23 | 1.44
11 |Lime,Sulphurand Soda
16 L., 8 S.,
8 soda, 50 W. ut 124 64s 6 3.43 | 19 1.24

*Sulphur put in first, lime added.
+Lime first, sulphur added.

Simple lime & sulphur
California washes

Oregon & California
washes

6 |California wash

8 “c sé

=

‘

0

RECAPITULATION.
II 184 | March
ia) 183 6c
I&II) 266 |January
II 68 | March
dy 47 January
I 251 *

Lime, sulphur, & soda

J
|

1.33

TI. TABLE OF EXPERIMENTS WITH LIME AND SULPHUR PREPARATIONS
ON PLOTS OF 5 TO 12 TREES.

sept
Sept
Bene
No. of 4 Or- Infes-
Exper Insecticide chara|_rees Treated Potion ee
Degrees ent
12. |Oregon wash with Del.
hmoidy 220k. 15'S.,
1.5 Bo V., 50 W. ih a Mar. 24 1.91 61
13. |Oregon wash with Wis. |
limate. 20 L.,158S., |
PGS eS BUEN a ib Uta 5: 2.08 58
14 |Oregon wash with hy-
drated lime No. 1.
20 Te 5iSs,
eA avis DON ue 11 Oo). 2.18 56
15 |Oregon wash with hy-
drated lime No. 2.
ZOOS ae
1.5'B:.V., 50 W. os vil bees 2.18 56
16 |Calcothion. 4 5 a 2.0 55
17 +!Con Sol. 1 part to 40. be 9 Be tec 4.21 15
Ill. MISCELLANEOUS EXPERIMENTS.
Sept.
No. of I Ricld Or- T T ted ee Bone
Exper. nsecticide chara|_reesiTreated| tation nd
Degrees Pent
18 Scalecide I 31 | Mar. 24 2,00 47
19 |Whale-oil soap
2 lbs. to the gallon ig 117 eee ee | 9 65
20 |Tak-a-nap soap F
1 lb. to the gallon if 8 Tage 15

71

GENERAL RESULTS OF THE FOREGOING ELEVEN E,.XPERIMENTS.

An examination of the column of the preceding table showing
percentages of “September benefit” for the various kinds of treat-
ment enables us to divide at once the series of experiments into four
groups—three of three experiments each, and one of two. The first
six experiments were all made in the same orchard, and all in March.
It is especially interesting to see that the first three, in which the in-
secticide was a simple lime and sulphur solution without salt or blue
vitriol, show ratios of 74 to 79 per cent. of benefit, with an average
of 76.3, while the next three experiments, all made with the “Cali-
fornia wash,” the composition being the same as that of the preced-
ing three except that salt was added, give ratios of benefit ranging
from 64 to 68 per cent., with an average of 65.

These experiments strongly indicate, if they do not substantially
prove, that the addition of salt to the lime and sulphur is a detriment
rather than a benefit, since a difference of 17 per cent., or more
than one sixth, in the ratios of apparent benefit, under conditions
otherwise so uniform, can scarcely be accounted for in any other
way.

The next group of experiments, 7 to 9 of our series, when con-
trasted with Experiments 4 to 6, show a difference in final effect of
spring and midwinter sprayings. The average benefit of the ‘“Cal-
ifornia wash’’ applied to 187 trees in March was 65 per cent., while
that of the Oregon and California washes applied to 320 trees in
January was 46 per cent.—a difference of 41 per cent. in favor of
the spring treatment. The January group of three experiments does
not compare exactly with the March group of three, since two of
the former were made on a different orchard from the latter, and
were made with the “Oregon wash” instead of the “California
wash.” If, however, Experiment 8 be compared with Experiment 6,
in which all the conditions were identical except the time of spray-
ing, we get the same difference of ratios of benefit as before—45 per
cent. for the January treatment and 64 per cent. for the March
treatment. . |

Furthermore, the last two experiments, 10 and 11 of our series,
contrast still more strongly with the three preceding, giving but 19
and 23 per cents of benefit, with an average of 21 per cent. as com-
pared with 46 per cent. for the preceding group. ‘This difference
of more than 100 per cent. can be accounted for only on the suppo-
sition that the cold solution of lime and sulphur made with soda
was far less efficient as an insecticide than the ordinary form of
Oregon and California washes made by boiling.

72

One additional inference may be drawn from a comparison of
Experiments 1 and 4 on the one hand with 3 and 6 on the other. In
each of the former pair the lime was slaked in water in which the
sulphur had been first stirred up. In each of the latter pair the lime
was put in first, and the sulphur was added during the slaking proc-
ess. That there is an apparent advantage in the first method of
preparation is shown by the difference of 5 degrees of benefit be-
tween Experiments I and 3, and 4 degrees of benefit between Experi-
ments 4 and 6. It thus appears that solutions made by stirring the
sulphur into the hot water first and adding the lime to this mixture,
are more efficient than if the order of procedure is reversed.

It follows from this discussion, as a general conclusion, that
simple solutions of lime and sulphur made by boiling, without salt
or blue vitriol, the sulphur being added to the water first, had
much the best insecticide effect in these orchards; that the March
spraying was nearly twice as effective as the January spraying; and
that the soda solutions of lime and sulphur made without heat had
a final efficiency less than half that of the boiled solutions applied at
the same time.

Minor Experiments.—Six experiments with other lime and sul-
phur mixtures were made on too small a scale to compare with the
eleven preceding, but with results which seem to me worthy of rec-
ord, particularly as they are fairly uniform for this group of insecti-
cides notwithstanding the small number of trees used in each ex-
periment.

From 5 to 12 trees were sprayed with various forms of the
“Oregon wash,” with “Calcothion,” and with “Con Sol,’ all in
March from the 22d to the 24th, and all in Orchard II. Four of the
insecticides used were forms of the “Oregon wash” made with dif-
ferent brands of hydrated lime instead of ordinary lump-lime from
the kiln. In all cases 20 pounds of the lime, 15 pounds of sulphur,
and 1% pounds of blue vitriol were used to 50 gallons of water, the
only difference being in respect to the kind of lime, the so-called
\Visconsin “Limate’ being used in one, the Marblehead hydrated
lime in two others, and the Delaware “Limoid”’ in the fourth. These
were applied in each case to II or 12 trees, and the effect was ascer-
tained by the inspection method used in the larger experiments.

The resulting benefits ranged from 56 to 61 per cent., as tested
by the September inspection, using the September condition of the
check plot of Orchard II. as a basis of comparison. These mixtures,
with their average benefit of 58 per cent., were apparently less effi-
cient than the California washes used at the same time, which give
a benefit of 65 per cent. The “Calcothion,” applied cold without di-

73

lution, as it was received from the manufacturers, was used on only
5 trees, with a ratio of September benefit figured at 55 per cent.—
substantially the same as that of the Oregon washes just referred to.
“Con Sol,” diluted with water at the rate of 1 to 40, and applied cold
to 9 trees, gave a ratio of only 15 per cent. of benefit. The Oregon
washes cost at the rate of $1.07 per hundred gallons for materials;
“Con. ol; $2405) and “Calcothion,” $5.

It may be provisionally inferred from these small experiments
that neither ‘of these two compounds has any advantage over the
better-known washes except in point of convenience, and this must
be paid for by a considerably higher cost than that of the lime and
sulphur mixtures—more than twice as great for “Con Sol,’ and
nearly five times as great for “Calcothion.”’

MISCELLANEOUS ADDITIONAL INSECTICIDES.

Only one of the kerosene insecticides was tried on a number of
trees sufficient to give any permanent value to the experiment.
The soluble petroleum compound known as “Scalecide,’ applied
March 24 in a 5 per cent. mixture with water to 31 trees in Orchard
I., showed a September infestation of 2.6 degrees, equivalent to a
benefit of 47 per cent.—decidedly less than that of any of the lime
and sulphur washes used in March, as shown by Table I., and con-
' siderably less than that of the Oregon washes of Table II. It seems to
‘belong, in insecticidal effect, with the Oregon and California washes
as applied in January, its 47 per cent. of benefit being substantially
the same as the 46 per cent. of the latter treatment. Its cost was
$2.50 per hundred gallons—essentially the same as “Con Sol”—and
its benefit was three times as great. It was apparently the best of
the ready-made insecticides tested by us last year.

A kerosene preparation known and sold as “Frutolin” was tried
March 24 on 3 trees, and several variations of a 20 per cent. kerosene
mixture made with water and hydrated lime in lieu of soap solution
were applied on the same day to 5 more trees, all in Orchard I.
The results were essentially the same with all these mixtures, so far
as one can judge from these small experiments. ‘The trees treated
averaged 4 degrees of infestation September 10, giving a benefit
ratio of 19 per cent. as compared with the check of their orchard.
The cost of the “Frutolin” mixture was $25.10 per hundred gallons,
and that of the so-called emulsions made with kerosene and
lime was $1.07.

Two simple soap solutions were used, whale-oil soap on 117
trees, and ‘“T'ak-a-nap” soap on 8 trees, the former in Orchard II.

74

and the latter in Orchard I. The whale-oil soap was used March 23
and 24 in the ordinary ratio of 2 pounds to the gallon of water on a
plot immediately beside the check plot of its orchard. As the row
adjacent to the check showed much the highest infestation of any
one of the seven, it has been thrown out in the comparison.

September 10 the infestation of this plot was reckoned at 1.9 de-
grees, which, compared with that of the check plot at the same time,.
gives a benefit ratio of 65 per cent.—making this solution virtually
the equivalent of the California washes made with salt, as shown in
Table I. Its cost, $8 per hundred gallons of the solution—nearly
eight times that of the California washes,—is the most serious ob-
stacle to its general use. Except for its occasional destruction of
blossom buds of the peach and other especially sensitive fruits, it
would still remain the most desirable for use on a small scale. For
the apple orchard, if the difference in expense is not worth consider-
ing, it is to be recommended as among those next in efficiency to the
simple lime and sulphur washes.

‘“Tak-a-nap” soap dissolved in cold water at the rate of one
pound to the gallon, and applied March 24 to 8 trees in Orchard L.,
gave an apparent September benefit of 15 per cent. The cost is $5
for one hundred gallons.

A caustic-soda solution made with water at the rate of 1 pound
to 6 gallons and applied to 3 trees March 24 produced no percep- .
tible effect, these trees being, in fact, worse infested in September
than they were in January, and even worse than were the trees of
the check plot at the September inspection.

Mention may also be made of Bowker’s Tree Soap, used on only a
single tree, but there apparently with very good effect. It was ap-
plied March 24 to a badly infested tree in Orchard I. at the rate of
2 pounds of soap to a gallon of warm water.

At the time of the May inspection 100 scales from this tree were
counted, all of which were dead, and Mr. Taylor remarks that he
could not find a scale on this tree alive, though he scraped and ex-
amined most of the twigs to their tips. By September, however,
this tree was moderately infested, possibly by invasion from adja-
cent trees which had been treated with kerosene emulsion,

This soap costs 714 cents per pound in 100-pound kegs, bringing

the cost of the spray to $15 per hundred gallons.

Cost oF MATERIALS .

The cost of all the materials contained in the various insecticides
used in these experiments is shown in the last column of the tabular

79

summaries, with the exception of those used in certain minor experi-
ments, which have been separately given. This cost, stated in
terms of one hundred gallons of the spray diluted and otherwise
made ready for actual distribution, is based on the following rates
for materials, which are those actually paid by us, or, in a few minor
cases, those furnished us by the manufacturers. None of these
prices includes freight.

Lime. 90 cents per bbl. of 196 lbs.

Sulphur. $2.30 per cwt., bought in ton lots.

Salt. 33 cents per cwt., by the bbl.

Blue vitriol. $6 per cwt.

Caustic soda. $4.50 per cwt., in 10-lb. cans.

Whale-oil soap. 4 cents per lb., by the bbl.

Tak-a-nap soap. 5 cents per lb., in 40-lb. packages.

Kerosene. 1244 cents per gal., by the bbl.

Marblehead hydrated lime No. 1. 50 cents per cwt.

i ue ce 2) oo Cente per, cwt.

Wisconsin limate. 50 cents per cwt.

Delaware limoid. Highest grade, $5. per bbl. of 200 lbs.; cheaper
grade, $2.50 per bbl., or $14. per ton.

Calcothion. 5 cents per gal., if bought by the bbl.

Con Sol. $1. a gal.

Frutolin. 66 cents per liter (1.06 quarts) in cases, each containing a
dozen liter cans.

Scalecide. 50 cents per gal., in 50-gal. bbls.

The cheapest of these washes, counting cost of materials only, is,
‘fortunately, the one found most efficient in these experiments,
namely,the simple lime and sulphur wash in the ratio of 15, 15,50, and
costing 84 cents per 100 gallons when ready for spraying. The next
in order is the common “California wash” of lime, sulphur, and salt
(15, 15, 15, 50), costing 94 cents per hundred gallons. The “Ore-
gon wash” made by the old formula still in most general use, and
containing 15 pounds of lime, 15 pounds of sulphur, and 1% pounds
of blue vitriol to 50 gallons of water, costs $1 per hundred gallons;
and the simple lime and sulphur mixture with 21 pounds of lime
and 18 pounds of sulphur to 50 gallons, costs $1.03. The “Oregon
wash’ with the lime (of whatever form) increased to 20 pounds,
amounts to $1.07 per hundred gallons; and the lime and soda
washes, from $1.24 to $1.44, dependent upon the proportions of the
ingredients as given in Table I., Experiments to and 11.

The next in order of cost is ‘Con Sol,” at $2.40 per hundred gal-
lons, 1 part of the insecticide to 40 of water; and then ‘‘Scalecide,”
$2.50 per hundred gallons, when used in a 5 per cent. solution. The
kerosene emulsions made with hydrated lime and diluted to contain

76

20 per cent. of kerosene, cost $3.62 for a hundred gallons of the
diluted mixture. ‘“Tak-a-nap’’ soap, a pound to the gallon, costs $5
a hundred gallons, and the ordinary solution of whale-oil soap, $8
for the same amount. ‘‘Frutolin’” costs $25.10 per hundred gallons
when diluted with 9 parts of water to 1 of “Frutolin,” as advised
by the manufacturers.

GENERAL SUMMARY.

1. The cheapest and most efficient of the eleven insecticide mix-
tures thoroughly tested against the San Jose scale were the simple
lime and sulphur mixtures (without salt or blue vitriol) dissolved by
boiling together. They cost, for materials, from 84 cents to $1.03 per
hundred gallons of the fluid spray, varying according to the propor-
tions of the chemicals used. Infested trees treated with these solu-
tions in March, bore about one fifth as many scales the following
September as companion trees not treated.

2. The next in value was the “California wash’ made with
lime, sulphur, and salt, at an expense of 94 cents to $1.07 per hun-
dred gallons, and the “Oregon wash” of lime, sulphur, and blue
vitriol, costing virtually the same.

3. There was a marked and very important difference in the
final effect of these washes and mixtures, dependent upon the time
of their application, the midwinter treatment yielding a result far
inferior to that of early spring.

4. The cold solution of lime and sulphur made with soda was
found less than one third as effective as the washes dissolved by
boiling. Its materials were also somewhat more costly, varying,
according to the proportions of the ingredients, from $1.24 to $1.44
per hundred gallons.

5. The petroleum preparation known as “Scalecide,”’ which has
the advantage that it may be prepared for use by simply diluting
with water, was found somewhat less efficient than the lime and sul-
phur mixtures, and cost about 21% times as much as the raw mate-
rials of those preparations.

6. Whale-oil soap compared very well with the “California
wash,” but at a cost approximately eight times as great.

7. Less confident statements may be made with reference to Ore-
gon washes made with hydrated lime, and to the commercial insecti-
cides known as “Con Sol” and “Calcothion,” experiments with these
substances having been made on too small a scale to warrant final
conclusions. They strongly indicate, however, that, with the excep-
tion of “Con Sol,’ these mixtures have an insecticide value some-

,

cu

what less than that of the ordinary “Oregon wash.” “Calcothion”’
is applied as received, without either additional preparation or dilu-
tion. It has the disadvantage of a high cost, amounting to $5 per
hundred gallons.

8. Minor experiments with several additional insecticides are
briefly described on pages 72 and 73.

g. The expense of preparation of the mixtures to be dissolved
by boiling is so variable, according to the amount to be used, the
supply of available labor, and the kind and cost of fuel, that no at-
tempt has been made to estimate it. For all the lime and sulphur
solutions except those made with soda, and for whale-oil soap, it
amounts virtually to the cost of boiling successive quantities of fifty
gallons of water, each for 30 to 45 minutes.

SPRAYING APPLES FOR THE PLUM-CURCULIO.

It has been known for more than a hundred years that the
apple was subject to injury by the plum-curculio, but as this injury
has been commonly reckoned less important than that done by the
codling-moth, the matter has received, of late, comparatively little
attention until within the last six or seven years. Since the dis-
crimination of different market grades of apples has been generally
introduced—a grading based not only upon size and soundness, but
also upon superficial‘ appearance—the slight surface injuries done
by the new generation of the plum-curculio, both in laying the eggs
and in feeding on the fruit, have acquired a great importance. ‘The
consequence of a noticeable injury of this sort, although affecting
but little, and in many cases scarcely at all, the edible quality of
the apple so injured, is to reduce its selling value from No. 1 grade
to No. 2, the actual profits of the crop disappearing in this process.
These facts having been repeatedly brought to my knowledge by
Illinois horticulturists, I undertook to work out the causes of these
surface blemishes in general, and to demonstrate more accurately
than has hitherto been done means of preventing them by a destruc-
tion of the curculios themselves. Indeed, the importance of this
investigation has grown upon me as it has become evident that
these small superficial injuries very often give entrance through the
skin of the apple to bacteria and to fungus spores of various kinds,
causing rots and blights of the fruit which might be largely pre-
vented by a timely destruction of the insects.

SomE EARtIER EXPERIMENTS.

The first exact experiments with insecticides for the protection
of apples against the plum-curculio were those made at my office in
1885, on a small orchard hired for the purpose near Urbana, IIL,
the results of which were published in one of my reports*, and in
the Transactions of the Illinois State Horticultural Society for that
year. In this experiment, which was made primarily to test insecti-
cide measures for the destruction of the codling-moth, the effect on

*Misc. Essays on Econom. Ent., 1886, pp. 26-45.

79

curculio injuries was likewise ascertained. Eight trees were used,
4 of them being sprayed and 4 reserved as checks. ‘Two of the
trees were treated with Paris green, 1 with London purple, and 1
with lime. All applications were made eight times, beginning the
oth of June and continuing until September 3.

All the apples borne by these trees, 16,529 in number, both those
which fell and those which remained on the tree, were examined
one by one, and the results were tabulated for comparison. Al-
though this was my first work with orchard insecticides, and the
application was doubtless not made as thoroughly as would now
be done, the general result of the work with Paris green was to
save uninjured on the trees 56 per cent. of the apples which would
otherwise have been injured by curculios—a percentage less than
was to have been expected in orchard practice because, as noted at
the time, there were other bearing trees in the orchard, from which
those treated unquestionably became reinfested to some extent. As
apples were not graded at that time, no attempt was made to dis-
tinguish differences in the crop borne by trees sprayed and those
left unsprayed as checks, beyond the mere number of the injured
and uninjured apples; but results which I shall presently describe
make it certain that the actual percentage of benefit would have been
much greater than that indicated by these figures if I had also taken
account of differences in size and quality of the fruit.

Because of repeated reports of general and important, though
slight, surface injuries to apples by insects in summer and fall, 1
sent an assistant, Mr. EF. S. G. Titus, through southern Illinois in
June and July, 1901, to observe and collect examples of these in-
juries, and such insects as might be held responsible for them.
Quantities of blemished fruit were sent to the office for careful
study, and as a means of rearing any insects which it might contain.

From this investigation it appeared that much the greater part
of the injury complained of was due to the plum-curculio, and that
the control of this insect would virtually protect the apple—a fact
reported to the Illinois State Horticultural Society for that year,
and published in its Transactions (p. 148).

Pursuing the subject further, I read at the meeting of this same
Society in 1902 an article* prepared by Mr. Titus, the greater part
of which was given to the work of the plum-curculio in the apple
orchard. In addition to a report of many careful observations, an
important suggestion was made in this paper to the effect that, since
injury to the fruit was least in well-cultivated orchards, cultivation

*“Tusects, other than the Codling-moth, Injurious to the fruit of the Apple,” by EK. S. G.
Titus. Trans. Ill. State Hort. Soc., Vol. 36, pp. 158-162.

80

at a time when the bulk of the curculios are in the ground passing
through their. transformations might have the effect to diminish
their number by killing them in the pupa state. For this purpose,
it was said, a midsummer plowing would be necessary, followed by
harrowing to break up the clods and expose the pupe more thor-
oughly to the weather. The prompt destruction of the fallen fruit
and spraying of the trees with Paris green were also prominently
mentioned.

The following year, in a paper* on “The Curculio and the
Apple” presented to the State Horticultural Society, Professor
C. S. Crandall, of the Horticultural Department of the Illinois Ex-
periment Station, gave the results of a season’s work, experimental
and entomological, in an orchard in the western part of the state.
This article reports the writer’s observations, and those of his as-
*sistant, Mr. James R. Shinn, with respect to many points of inter-
est in the life history and habits of the plum and the apple-curculios,
their numbers in the apple orchard, and their injuries to the apple,
together with the outcome of certain spraying experiments made as
a test of the insecticide method of controlling their injuries. En-
tomologists will be especially interested in the precise details of the
life history and in minor particulars concerning the habits of these
species.

The spraying operation was reported as unsuccessful, even thir-
teen to sixteen applications of Paris green, extending from May 15
to August 15, seeming virtually without effect. As only 120 trees
were used in these experiments out of an orchard of one hundred
and twenty-five acres, and as these experimental trees were divided
into plats of 10 trees each, it is evident that the sprayed trees were
subject to continued invasion from the surrounding orchard, suff-
cient, possibly, to obliterate the results of the treatment. A sugges-
tion which I have already mentioned—that of plowing and _ har-
rowing infested orchards in midsummer to destroy the pupz in the
earth-——is here reinforced with numerous exact observations as to
the time of pupation, and the depth to which the curculio larve
penetrate for their pupal transformations.

EXPERIMENTS OF I904.

Owing to the unfavorable outcome of these experiments of
1903 for the control of curculio injuries by the use of insecticides,
it became important that measures should be taken to test anew the
usefulness of the arsenical sprays, especially as these are necessary
to any program of fairly complete protection to the crop of apples

*Trans. Ill. State Hort. Society, Vol. 37, pp. 176-189.

81

on the trees. Destruction of windfalls and midsummer plowing
have the disadvantage that they lock the stable door after one of the
horses, at least, is stolen, since they can at most prevent only in-
juries by the new brood of curculios appearing after midsummer.
In the absence of poison sprays, an orchard freed of curculios in
midsummer—if this is possible—by plowing and harrowing, would
be liable to invasion and serious injury later in the season by insects
entering it from outside, and would also be exposed to injuries in
the spring and early summer of the’ following year. With these
facts in mind, I undertook, in 1904, a field experiment in southern
Illinois intended to test the practical value of an arsenical poison
directed immediately against the plum-curculio, with the under-
standing that similar experiments were to be carried on by the Hor-
ticultural Department of the State Experiment Station in another
part of the state. My experiment was placed in charge of my field
assistant, Mr. EK. P. Taylor, and this report is based on his field
notes and specimens.

The farm selected, after an examination of some twenty-five
fruit farms in southern Illinois, contained three small orchards ag-
gregating eighteen acres. It was situated two miles south of Car-
bondale, in Jackson county. ‘These orchards were chosen partly
because of the considerable crop which they bore—an unusual thing
that year—and also because the separation of the varieties with
which they were planted, enabled us to make, in most cases, check
and experimental plots of the same variety.

Woods Pasture

wt.

Ss
Pasture
ORCHARD,

SITE AND SURROUNDINGS OF EXPERIMENTAL ORCHARDS

ORCHARD NO.1
{
i}

82

The insecticide used was a compound of arsenate of soda and
acetate of lead commonly known as the arsenate of lead. It was
made by dissolving 12% ounces of the acetate of lead and 5 ounces
of arsenate of soda in separate vessels, and pouring the two solu-
tions, one after the other, into a barrel with 50 gallons of water.
Two barrels were placed in the wagon at once, each with a No. 2
Morrill and Morley spray pump carrying two lines of hose about
twenty-five feet long, furnished with twelve-foot extension poles
fitted with double Vermorel nozzles.

In spraying, as high a pressure was used as could be kept up by
hand; anda are mist of the spray was forced into the trees from
every side, care being taken to wet thoroughly all parts of the
foliage without causing the drops to run in streams upon the leaves.
The varieties of apples in the orchard will be referred to in giving
the results of the experiments.

Three sets of experiments were made by spraying four, six, and
eight times respectively, at intervals of about ten days, beginning
May 6 to 10, and ending July 28. At the time of the first spraying
at Carbondale, the apple-trees were in their first full bloom.

RESULTS OF E.XPERIMENTS.

As a basis for the discussion of the principal results of this ex-
periment, I have prepared the accompanying table showing espe-
cially the differences in quantity, number, and quality of apples
borne, by trees sprayed and by those without treatment. his table,
it will be noticed, is divided into two parts, an upper and a lower,
and for convenience in reference I have numbered the vertical col-
lumns from 1 to 12 and the horizontal sections of the table from
I to 8.

CuRCULIO SPRAYING EXPERIMENTS

Columns 1 2 3 4 is 6

o Times] Trees used Apples picke :

3 Plot spray- ESS Ki ‘i ee

ent.
ed No. | C’t’d Date Bushels | Number rs

zy | 1. Check} 0) LS 4 S. 16-20 15257 |. “2627. 92.2
Exper. ve yams Bs Ves hear weal =p (ry ieee are 28.59

5 | ue Check 0 34 a J 26-29) 1a 2,993 21.4

=o) )xxper. 6 32.) 93, | 515 26-29) | ag. 3,782 10.3

3 | Tl. Check| 0 20|. 3 S.17 16.25 =| -2;770 95.6
Exper. 6 20), 8 S.17 22. 3,063 30.7

4 |1V. Check | o | 145 (9) 4| “31.48 6.44 | 1,540 91.1

ihe Exper. 8 ID 4 | §. 16-20 24.44 3,198 18.5

83

CurcuLio Spraying ExpERIMENTS—Continued.

Z Columns 7 8 9 10 11 12
5 ae
¥ Injuries Yield Bushels Value
co) EAGLE prevented | increased increased
wa per cents, | per cents || Now No. 2 No. 3 times
- |1l. Check alas 622 ae |
~ | Exper. 69. ae 17.16 5.5 1.16 2.75
6 ele Check

Exper. 48, 40.

Ill. Check ; a0) 2573) 11.66

7 | Exper. 68. Shee | FEROS 3.25 6.66 2.5
g | IV. Check |

Exper. 80.

Orchard 1 (Plot I.).—By an examination of this table it may
be seen (Section 1, Columns 1 to 5) that all the apples on 4 trees
of Plot I. out of 111 of the Ben Davis variety which had been
sprayed four times with arsenate of lead, were picked, measured,
counted, and carefully examined between the 16th and the 20th of
September, and that all the apples on 4 other trees of this plot out
of 115 Ben Davises which had been left unsprayed as a check, were
also. picked, measured, counted, and similarly examined at the same
time. ‘These two lots of 4 trees each had been so selected at the
beginning of the experiment from the whole number in each lot as
to make the check lot the nearest possible duplicate of the lot which
had been sprayed, except, of course, in the mere matter of spraying*

SPRAYED 4TIMES NOT SPRAYED

eee Fe 6 eo

©£0@0e00@e0e8¢ @ @

eceheyeoeee
eee eeere ee 0 @
eee ey Heo eee eo
eeee foe Heo
eee © ee © 0 e Ce
epee ye
eeceeeee 8 ©

*
°
e
©
®

*
e
®

*

eceeeee ee @ @
ececoe Fe 0 eo @

ORCHARD NO! APPLES COUNTED FROM STARRED TREES

*The four sprayed trees used for comparison with the four check trees are those starred in
the sixth row from the middle line of the orchard. /The four trees used as checks are among
those starred in the fifth and sixth rows from the middle line.

84

The 4 trees not sprayed yielded 15.5 bushels of apples, and the
4 trees sprayed yielded 23.9 bushels (Section 1, Column 4), the
bulk of the yield being thus 54 per cent. greater for the sprayed
trees than for those unsprayed (Section 5, Column 8). In other
words the trees which had been treated, yielded one and a half times
as large a quantity of apples as those which had not been sprayed.

The number of apples from the 4 trees not treated (Column 5)
was 2,617, while that from the trees treated was 3,308—a differ-
ence of 26 per cent. in favor of the sprayed trees. That is, the
sprayed trees bore a fourth more apples than those which had not
been sprayed. We should notice, in passing, that the apples from
the trees not treated ran 169 to the bushel, and that those from the
treated trees ran 139 to the bushel—a difference of 21 per cént. in
average size of fruit in favor of the sprayed trees. ‘That is, the
apples on the trees which had been sprayed were one fifth larger,
on an average, than were those from the other trees.

All these differences were apparent without any special exami-
nation of the fruit with reference to injuries by curculios. When
these curculio injuries were distinguished and tabulated (Column
6), it was found that 92.2 per cent. of the apples on the unsprayed
trees had been injured by curculios making feeding-pits, egg punc-
tures, or both, and that 28.6 per cent. of the apples on the sprayed
trees were so injured. A simple calculation from these data shows
(Section 5, Column 7) that 69 per cent. of the apples which would
have been injured if no treatment had been applied, had been pro-
tected from injury by the arsenate spray.

Next, the total product of both lots of trees was separately and
very carefully graded as No, 1’s, 2’s and 3’s, by the standards of
the American Apple Growers’ Association adopted in 1903, (Sec-
tion 5, Columns 9, 10, and 11,) with the result to show that the
4 check trees yielded 114 bushels of No. 1’s, and the 4 sprayed trees,
17.16 bushels; that the check trees yielded 6.2 bushels of No. 2’s,
and the sprayed trees, 5% bushels; that 7.8 bushels of No. 3’s were
borne by the check trees, and 1.16 bushels by the trees which had
been sprayed. (See Plates I. and II.)

According to the best estimate we can make of the market
values of these three grades, if the No, 1 apples sell for $1, No. 2’s
might be expected to bring 75 cents, and No. 3’s, 25 cents or there-
abouts. Applying these estimates to these various lots of apples,
it appears that the actual value of the crop from the treated trees
was 234 times that from the trees which had not been treated
(Column 12).

85

To see whether the outer rows of trees were any more likely to
be heavily infested by curculios than the inner,—whether curculios
entering the orchard from outside would accumulate upon the outer
rows,—three trees in the sprayed lot were examined, one from the
middle and one from each end of the row farthest removed from
the check. No differences in amount of curculio injury were found
in these trees, as compared with the average for the plot in general,
with the exception of one of the three, which stood at a corner of
the orchard next a fringe of forest trees and brush. The fruit of
this tree, notwithstanding the four thorough sprayings with arsen-
ate of lead which it had received, had been injured by curculios to
the amount of nearly 87 per cent., showing an extensive immigra-
tion into the orchard from the adjoining woodland. As this con-
tained both hawthorn and wild cherry-trees it doubtless furnished
a constant breeding ground for curculios.

Foreseeing difficulties of this kind, and also the probability of
a mutual influence of check and experimental plots, the precaution
had been taken to select, quite early in the season, for comparison,
four trees from the center of each plot, and it is thus quite certain
that no outside interference or intermingling of effects influenced
the contrast obtained in this experiment.

Orchard 2 (Plots II. and III.).—We turn next to the second
orchard (Sections 2, 3, 6, and 7), one half of which was sprayed
six times in succession, the other half being left as a check. As a
part of these apples were of an early variety (Benoni), and a part
were of a late variety (Ben Davis), I will give the results for these
two varieties separately.

Thirty-two Benoni trees (Plot II.) were sprayed six times in
this experiment, in comparison with 34 Benoni trees left as a check,
and the apples borne by 3 trees from each of these two lots were
picked, measured, counted, and examined July 26 to 29 (Section 2,
Columns 1 to 5), the two sets of trees having been so selected as
to make the check lot the nearest possible duplicate of those which
had been sprayed. The 3 trees not sprayed yielded 11.4 bushels of
apples, and those which had been sprayed yielded 16 bushels (Col-
umn 4)—an increase of 40 per cent. in the bulk of the yield as a
consequence of the spraying. ‘The 3 trees which had not been
treated bore 2,593 apples, while the 3 treated trees bore 3,782 (Col-
umn 5)—a difference of 47 per cent. in favor of the treated trees.
That is, the sprayed trees bore nearly half as many apples again as
those which had not been sprayed. The average size of the apples
was approximately the same for both lots—228 per bushel for the
untreated trees, and 236 for the treated.

86

Te ehv Tel

“OFWLL UNO GIAVHdS SIIML YNOS WOU SIIddy azawUo

“TT, Shaler

= 8d3AWudS LON SASHL UNOS WOU SalddV¥.

Me,

88

‘JTII FLV Id

7

SAWILXIS G3AvudS $3aU.l FAYHL WOYS Saddv Gaayuo

a

%

ioe)

“AI FLV Id

90

Turning next to the ratios of curculio injury to these Benoni
apples (Column 6), we find that 21.4 per cent. of the fruit of the
unsprayed trees had been injured by curculios, and 10.3 per cent. of
that on the sprayed trees, 48 per cent. of the apples which would
have been injured having been protected from injury by the arsen-
ical spray. ‘These Benoni apples were harvested in July, but were
not graded into market classes. I consequently have no data as to
the total money benefit of the spraying shown by this Plot II.

On the other part of this orchard (Plot III.) sprayed six times
(Sections 3 and 7), were 20 Ben Davis trees which are to be com-
pared with an equal number of this variety left unsprayed as a
check. From each of these lots again 3 trees were taken for critical
comparison of the product of those sprayed with that of those un-
sprayed (Section 3, Columns 1, 2, and 3). The final count on all
these trees was made September 17. The 3 trees not sprayed gave
16% bushels of apples, while the 3 trees sprayed yielded 22 bushels
(Column 4)—an increase of 34 per cent. in quantity of apples as a
consequence of the spraying. ‘The 3 Ben Davis trees which had not
been treated bore 2,770 apples, while the 3 treated trees gave 3,063
(Column 5)—a difference of only 11 per cent. in favor of the
treated trees. ‘The unsprayed apples on these trees ran 170 to the
bushel, and the sprayed apples, 139 to the bushel—a difference of
24 per cent. in size of fruit in favor of the trees which had been
sprayed.

With respect to the curculio injury to these Ben Davis apples
we find that 95.6*per cent. of the unsprayed fruit had been injured
by curculios, and 30.7 per cent. of that sprayed; or, in other words,
that 68 per cent. of the apples which would have been injured had
been protected from injury by the treatment received.

Looking now to the quality of the fruit from these Ben Davis
trees, which had been sprayed six times in all (Section 7, Columns
g, 10, and 11), we find that the 3 unsprayed trees examined gave a
yield of 34 of a bushel of No. 1 apples, while the 3 sprayed trees
yielded 12.06 bushels; that the unsprayed trees gave 334 bushels
of No. 2’s, the sprayed trees 3% bushels; that the unsprayed trees
yielded 1124 bushels of No. 3’s, and the sprayed trees 624 bushels.
(See Plates III. and IV.) Reducing these quantities to comparable
money values by the prices already assigned, we find that the actual
value of the crop from the treated trees was 2% times that from
the trees which had not been treated.

Orchard 3 (Plot IV.).—In the third and last orchard on which
I have to report, the check and the experimental sections do not cor-
respond closely, the sprayed trees being all Winesap and Ben Davis,
late varieties only, and the check lot almost entirely of early varie-

91

ties. As the early varieties were harvested July 15, they were less
exposed to injury than the fruit on the sprayed trees, which was
_ harvested from September 16 to 20. This is a difference, however,
which tends to diminish the contrast between the sprayed and un-
sprayed trees, and thus to show, if anything, a smaller result from
spraying than was actually obtained.

The Winesap and Ben Davis trees, 119 in number, were sprayed
eight times in succession, and the fruit from 4 of these trees (3 Ben
Davis and 1 Winesap) was picked and examined with reference to
curculio injuries. ‘The unsprayed orchard used as a check on this
experiment contained 145 trees, all Sops of Wine and other early
varieties except 4 Ben Davis (see Section 4, Columns 1, 2, and 3).
The fruit from 9 of these check trees was examined July 15, all
Sops of Wine except 1 Ben Davis. ‘These yielded 3,463 apples,
making 1434 bushels, equal to 1,540 apples, or 6.44 bushels from 4
trees (Columns 4 and 5), while the 4 trees sprayed, the apples from
which were picked September 16 to 20, yielded 3,198 apples, mak-
ing 24% bushels. These differences in number of apples and bulk
of yield can not properly be taken into account in this case, because
both might well be attributable, at least in part, to the difference in
variety between the sprayed and the check trees from which the
fruit was counted.

The curculio injuries on the 9 unsprayed trees had affected an
average of g1 per cent. of the apples (Column 6), and on the 4
sprayed trees, an average of 181% per cent., from which it appears
(Section 8, Column 7) that 80 per cent. of the apples which might
have been injured by curculios if no treatment had been applied,
had been saved from such injury by the arsenical spray. Here
‘again it is possible that a varietal difference in susceptibility to
curculio injury may have affected these percentages.

Cost OF THE OPERATION.

The reader will be especially interested to know the cost of our
operation, figured in terms practical to the fruit grower. I have
worked this out in full detail for the 292 trees sprayed in these
orchards, including the actual price of materials purchased in the
ordinary markets, the amount of materials used, and the labor of
application at $1.25 a day and board for men employed, and $2.50
a day and feed for a team. Without entering into details, unnec-
essary for my purpose, I find that the total cost ranges from 4 to
5 cents per tree for each treatment, or 17 cents per tree for the four
treatments found most effective. Of this only 2 cents was for ma-
terials, the remaining 15 cents being for labor of man and beast,
much of which, in many cases, the fruit grower might supply with-
out special outlay.

92

SUMMARY OF SPRAYING RESULTS.

Finally, to sum up in a word the most important practical re-
sults of the orchard experiment with arsenate of lead, we may say —
that four sprayings of apple-trees of late varieties, exposed to a
very heavy attack by the plum-curculio, the first spraying applied in
early May just as the trees are coming into bloom, and the others at
intervals of 10 days thereafter, the whole operation costing 17 cents
per tree, may be expected to increase the yield of the orchard about
one half, to increase the average size of the fruit by about a fifth,
and so to improve the quality of the apples that they should be worth
from 2% to 3 times as much as if the orchard had not been sprayed.

Porson TESTS OF SPRAYED APPLES.

The arsenate of lead used in experiments described in this paper
is an unusually adhesive insecticide, remaining upon trees in visible
quantity weeks and even months after it has been applied. Evident
traces of the mixture were still visible in October on leaves which
had fallen from trees sprayed with the arsenate of lead July 4. In
view of this fact is seemed to me important that experiments should
be made to determine the amount of poison carried by apples
treated with this insecticide within a reasonable limit of time after
the spray was applied. I consequently directed, in 1905, the spray-
ing of apple-trees with various arsenical compounds, and among
others with the home-made arsenate of lead, and obtained analyses
of the peelings of apples so sprayed taken from 2 2 trees within a day
of the application of the insecticide, and from a third tree 2 months
thereafter.

The first of these trees, of the Duchess variety, received 2 spray-
ings with the arsenate of lead—the first June 9 and the second
July 4—not having been previously sprayed at all that year. In
both these sprayings the insecticide was used 4 times the common
strength—12¥4 ounces of acetate of lead and 5 ounces of arsenate
of soda to 12% gallons of water instead of the usual 50 gallons.

The next day, July 5, six apples, averaging two and a fourth
inches in diameter, were carefully picked from this tree by the stem
and peeled at once, the apple being held upon the point of one knife
while it was peeled with another, to avoid removing any part of the
poison unnecessarily. ‘The peelings were then dropped into a dry,
clean, new Mason jar and submitted for chemical analysis to Dr.
Wm. M. Dehn, of the Chemical Department of the University of
Illinois. It should be said that the weather in the interval between
spraying and collection of the apples had been dry. According to
Dr. Dehn’s report, these apple peelings thus collected yielded 36.6
parts per million of arsenious acid, enough to equal .2562 grains of

93

arsenic to an avoirdupois pound of the sample peelings. This would
mean that one would have to eat approximately four pounds of
apple peelings to get a grain of arsenic if the fruit were taken the
day after spraying from a tree which had received four times the
usual strength of this insecticide.

Another tree, a Benoni, differed especially in two respects from
the foregoing. It had been sprayed three times by the owner earlier
in the season, and it was sprayed twice by us—June 9 and July 4—
but with arsenate of lead in the strength usual in practical orchard
work, that is 1214 ounces of acetate of lead and 5 ounces of arsen-
ate of soda to 50 gallons of water. The earlier sprayings were as
follows: First spraying about April 3, before the appearance of
the bloom, with 3 pounds copper sulphate, 5 to 6 pounds lime, 2
ounces arsenate of soda, and 2 ounces Paris green, to 50 gallons
water; second spraying about April 26, just after the bloom had
fallen, with 2 pounds copper sulphate, 1 pound Lorenberg’s arsenate
of lead, 2 ounces Paris green, 3 to 4 pounds lime, and 50 gallons of
water. Rain fell more or less for three days after ‘this second
spraying. The third spraying, about May 3, was with 2 pounds
copper sulphate, 3 to 4 pounds lime, 1 pound Lorenberg’s arsenate
of lead, 2 ounces Paris green, and 50 gallons of water.

‘From this tree six apples averaging two inches in diameter were
picked July 5, the day after our own second spraying, with the pre-
cautions described above. The peelings tested by Dr. Dehn yielded
32.9 parts of arsenious acid per million, equivalent to .2303 grains
of arsenic per pound of the samples.

It will be noticed that, although the insecticide here used con-
tained only one fourth as much of the arsenate as that applied to
the Duchess tree, the percentage of arsenic remaining on the fruit
was nearly as large.

The third tree treated was a Rome Beauty, sprayed, like the
preceding, three times, April 3, April 26, and May 3, approxi-
mately, with combinations of Bordeaux mixture and arsenical in-
secticides, and further sprayed, June 9 and July 4, with home-made
arsenate of lead at the rate of 121%4—5—12%; that is, like the
first tree, with four times the usual strength.

The apples were picked from this tree September 4, two full
months from the time of spraying. Those chosen showed more |
than the average amount of residue of the insecticide on the fruit.
They were picked into baskets, poured into a box where they were
packed closely by hand, and shipped to the office at Urbana, being
given average shipping treatment. Ten apples were later taken
from the box and carefully peeled, the peelings being submitted, as
before, to Dr. Dehn for examination. Notwithstanding the long
exposure in the orchard, the report on the arsenical contents of this

94

material is very similar to that of the preceding determinations.
The arsenious acid was found at the rate of 40.1 parts per million,
enough to give .2807 grains per pound of the apple peelings. One
would thus have to eat about three and a half pounds of these peel-
ings to get a grain of arsenic.

Two grains of arsenic is a fatal dose, and one thirtieth to one
tenth of a grain is a medicinal dose. For the first, one would have
to eat seven or eight pounds of these apple peelings; and for the
second, from two to seven ounces. While these facts are not at all
alarming, they suggest discretion in the use of this insecticide and
in the subsequent handling and disposal of the apples. We also
need further experiment with various strengths of the spray and
with various kinds and amounts of subsequent exposure of the fruit.
Nevertheless, in view of the fact that apple peelings are rarely
eaten in any quantity, I think that no hesitation need be felt to sub-
stitute the arsenate of lead for the more usual insecticide sprays
if the facts here given are borne in mind and duly allowed for.

THE NEUTRAL ZONE IN SPRAWNG EXPERIMENTS.

It has been customary in making field insecticide experiments to
apply the chosen treatment to a certain area, leaving a correspond-
ing area immediately beside it untreated, as a check, the utility of
the treatment being determined by a comparison of subsequent con-
ditions on these two tracts. Attention has already been called by
Gillette,* Weed,? and myself? to the fact that the results of such
experiments must be somewhat affected by the spread of insects
from the so-called check plot to the experimental plot, but nothing
has been done to demonstrate this proposition experimentally, or to
show just how important this mutual influence of check and ex-
perimental plots may be.

In the spraying experiment conducted in Orchard I., as above
described in this article, the opportunity was improved to ascertain
to what extent the curculios spread from one part of the orchard to
another—to what extent, that is, one must guard against vitiation
of results of spraying experiments by the spread of the curculios
from unsprayed trees to those which have been sprayed. ‘This or-
chard, it will be remembered, was divided into two equal parts, each
virtually square, on one of which all trees were sprayed four times
with arsenate of lead, beginning May 6 and following at intervals
of ten days thereafter, while the other part was left unsprayed as a
check. ‘The apples in this orchard were of the Ben Davis variety,
and were harvested September 20. At this time all the apples

*Bull. 9 (1890), la. Agr. Exper. Station, pp. 383-384.

+Bull. 23 (1890), Ohio Agr. Exper. Station, p. 226; Agricul. Science, Apr., 1890, p. 97.

+‘ Arsenical Poisons for the Codling-moth.” Bull. 1 (1887), Office State Ent. II11., p. 9;
Fifteenth Report, State Ent. IIl., p. 13.

95

borne by three trees which had not been sprayed, but which stood
in the row next the sprayed half of the plot, were counted and ex-
amined in comparison with the product of ten other trees taken at
various points in this unsprayed part of the orchard: (See dia-
gram, p. 83 and table on p. 97). Ejighty-one and five tenths per
cent. of the apples on these 3 trees next the experimental plot had
been injured by the curculios, and 90% per cent. of the apples on
the ro trees farther back,—a difference of 8.8 per cent. of all the
apples on these trees, which can only be accounted for on the sup-
position that more curculios went from the three trees nearest the
sprayed half of the orchard into that half than came into it from
that half.

Next, three trees which had been sprayed and which stood in
the row nearest the unsprayed part of the orchard were similarly
examined, with the result that 4314 per cent. of the apples on
these trees were found to have been injured by curculios, while
261% per cent. of the apples on to other trees taken elsewhere in
this sprayed plot were so injured. That is, 16.8 per cent. more of
the fruit on the trees standing nearest the unsprayed portion was
injured than on the trees farther back.

It will be seen that the increase of average injury to apples on
unsprayed trees near the check plot was nearly twice as great as
the decrease of injury on the unsprayed trees standing next the
experimental plot. This can only mean that the excess of curculios
on the unsprayed fruit to which their greater injury. was due did
not all come from the unsprayed trees in the adjoining row, but
that approximately half of them must have come in from remoter
parts of the experimental plot. In order to see how far this mutual
effect of one plot on the other actually extended inward in either
direction from the dividing line, apples were picked and counted
separately for each tree from a series of 14 trees running length-
wise of the orchard at right angles to the dividing line between the
two plots. It was found in this way that notable dimunition of cur-
culio injury on the one side and increase on the other did not extend
so far as the third row from the dividing line in either direction;
in other words, that it seemed limited to the first two rows on either
side of that line.

To test this conclusion in a more general way, the percentages
of curculio injury to apples were figured separately for all trees in
each cross-row from which any fruit was picked, beginning at the
outer end of the sprayed half of the orchard and ending at the op-
posite end of the unsprayed half. The details are shown on the ac-
companying table (p. 97,) from which it will be seen that 12 trees
in six different transverse rows of the sprayed half of the orchard,
ranging from the first to the ninth row, bore from 26 to 30 per cent.

96

of injured apples,—excluding for the moment a single exceptional
tree in the seventh row, which gave but 16 per cent. of injury. That
is, with this exception, the ratios ran from row to row with virtual
uniformity as far as the third row from the dividing line. In the
other half of the orchard, that left unsprayed as a check, the injury
on 10 trees distributed through six rows—from the fourteenth to
the twenty-second—ranged from 87 to 99 per cent., and in this
series also there is no uniform progression as one goes from the
dividing line outward.

We may make this influence of a proximity of check and ex-
perimental plots more definitely apparent by saying that if the two
adjacent rows only had been brought into comparison the difference
in injured apples would have been only 38 per cent., while the real
effect of the treatment was a difference of 63 per cent. Or, to put
the facts still more definitely, a comparison of the product of the
adjacent rows would indicate a saving, by spraying, of 47 per cent.
of the apples which would otherwise have been injured, while the
real saving was one of 70 per cent. The apparent benefit would be
but two thirds the actual.

We find, in short, two to four rows running through the center
of this orchard, one or two in each of the two plots, the product of
which has been rendered unfit for use in an exact comparison of
the condition of these two plots with reference to experimental re-
sults. Such a strip must evidently always exist under similar cir-
cumstances; a kind of neutral zone belonging properly to neither
plot, and unfit for comparison or for use in a discussion of the out-
come of an experiment. The importance of this conclusion is evi-
dent when one scans the published statements of similar experiments
and finds that in many cases the adjoining plots are so narrow that
nearly or quite all cf both must lie in this neutral zone. Sometimes,
indeed, one can not learn from the description of an experiment the
form or dimensions of the plots, and consequently can not judge how
far some portions of each or either may have been removed from
this central belt. Any experiment of the kind on diffusible insects
or fungi which does not take these facts into account, and from the
discussion of which a sufficient central strip is not omitted, must
be regarded as unsatisfactory, if not rejected outright as inexact.

50th the amount and the extent of the mutual influence of check
and experimental plots will vary greatly with different insects, and
with the same insect species under different conditions of abundance
and different kinds of treatment. Where infestation is unusually
heavy this interference with effects of treatment would, other things
being equal, be more pronounced. ‘To determine, in any case, how
much of a central strip must be omitted, it would be necessary to

Q7

make some such preliminary test as I have described, or, if the en-
tire product of the plots were harvested, to keep the different parts
of it distinct, rejecting those data which show an evident influence
of one plot upon the other.

In an ordinary plot experiment, if I infer from the outcome of
the treatment of a lot of trees in the midst of an orchard what will
happen if an entire isolated orchard were similarly treated, I
tacitly assert that such a plot, so situated, is so like an isolated
orchard in all that concerns my experiment that the one may be
substituted for the other. As a matter of fact, however, while a
small part of an orchard is analogous to the whole of it in many
particulars, it may differ from the whole in just those particulars
and conditions which most strongly affect my problem.

Since reasoning by analogy is the only process possible in such
a case, we must first make this analogy practically complete—must
establish the essential similarities between our experimental plot and
an entire orchard—hbefore we can reach any safe conclusion as to
the practical application of the experimental results. This I have
done to the best of my ability in the experiment here referred to,
and | venture to think that like results may be expected, under sim-
ilar conditions, from a repetition upon entire orchards of the treat-
ment here described.

OrcHARD I. SprayED PuLoT, Rows 1 To 11; anp CHEck, Rows 12 'ro 22

Trees Per cent.
BON examined injured VERA Be
1 2 28.95
2 0
3 1 29.89
4 O
i) 3 29.73
26.53
6 4 28.59
7 1 1G,
8 0
9 1 26
10 0
ijt 3 43.33 43.33
12 3 81.5 Sica
13 0
14 2 92.23
U5) 0
16 3 88 .08
17 1 87.7
90.33
18 2 87.19
19 0
20 i RIE
21 0
22 1 98 .96

98

DIAGRAM OF SPRAYING EFFECTS WITH ARSENATE OF LEAD.

(Showing mutual influence of check and experimental plots.)

ieee Plot (rows). Check Plot (rows).

a Wat IE IIE ie te de Ts i 2) ot 22.

lannmaecanl RRRRRREEEEl
NERAERAGHOIINGHEE BEER
(HRBSERERERERCREER ES

The above. diagram is simply a graphic representation of the
data of the preceding table. The vertical lines represent the rows
of trees in Orchard 1, except the central line, which marks the di-
vision between the half of the orchard which was sprayed and the
half left unsprayed as a check. ‘The horizontal lines, numbered
from 10 to 100, indicate percentages of injured apples. ‘The broken
line crossing the diagram from left to right intersects the vertical
line for each row at a point corresponding to the percentage of in-
jured apples from that row. It will be noticed that the eleventh
row of the series is the experimental row next to the check plot,
and that the twelfth is the check row next to the experimental plot.

wy

'The influence of these plots one upon the other is shown by the
strong, upward course of the broken line from the ninth to the
eleventh rows, and the downward course from the fourteenth to
the twelfth. The short horizontal lines, one on each side of the
diagram, indicate the average percentage of injury on check and
experimental plots respectively, with the exception of rows eleven
and twelve. ‘The distance between the inner ends of these lines is
a measure of the benefit resulting from the spray, and the distance
from the inner end of each line to the point where the broken line
crosses the vertical, is a measure of the influence of the other plot
through the unequal interchange of curculios.

THE ‘COTTONY MAPLE SCALE IN ILLINOIS,

The cottony maple scale* is a native insect parasite of the soft
maplet+, rarely if ever injurious to the scattering trees of this species
growing in natural forests, but so destructive to them, and to other
ornamental trees as well, where these are grown in rows or groups
along streets or in parks and on private lawns, that its control has
become an object of primary importance to all owners and lovers of
some of our most beautiful and popular American trees. In and
about Chicago especially, it has destroyed, within the past five years,
thousands of trees, beautiful and valuable in themseives, and still
more highly valued because of the associations attached to them, ‘To
do our best to save these noble but helpless products of nature from
a slow and unsightly death by parasitic disease, must be the wel-
come duty of all who appreciate the significance of trees in the life
of the people, and especially of those who live in our larger cities.

The history of this insect in [linois since 1867 exhibits succes-
sive periods of abundance and of scarcity, each averaging about four
or five years for the state as a whole. That is, throughout some
considerable part of the state, and often over most of it, the maple
scale has been injuriously abundant once in eight or ten years, and
its period of abundance has lasted, as a rule, about half this time.
In any given locality, however, it has usually been injurious for a
much shorter time, often for not more than one or two years. The
cessation of its injuries and its virtual disappearance from the trees
infested by it have seemingly been due almost wholly to the agency
of its insect enemies.

An exception to these statements is presented by the existing
outbreak of this insect in northeastern [linois, and especially in
Chicago and its suburbs to the north and west. Here, as shown by
observations of assistants of the office who have been repeatedly sent
through the park and boulevard systems of Chicago for an investi-
gation of insect injuries to shade trees and other ornamental vege-
tation, it has certainly been destructively numerous since 1901.
Indeed, according to information locally given to Mr, H. E. Weed,
of Chicago, it has been continuously injurious over some parts of
this area since 1886. This general persistence of an injurious in-
festation within the same district for so long a period is due to the

*Pulvinaria innumerabilis. +t Acer saccharinum.

100

101

Fie. 1. A Soft?Maple Twig badly infested with adults of the Cottony Maple Scale.
About natural size. (J. B. Smith.)

102

failure of the insect enemies of this scale to multiply at a sufficient
rate to check its rapid increase, and this is possibly the consequence
of an unfavorable effect of a city environment, although there is
some reason to suppose that the cottony maple scale has here ex-
tended northward into a latitude more favorable to itself than to the
insect enemies which commonly hold it in check.

Although no attempt has been made to define the present area of
destructive infestation in Illinois, this scale was reported to me dur-
ing 1905, in the current correspondence of the office, as locally
abundant in fifteen counties, namely, Winnebago, Lake, McHenry,
Cook, Dupage, Kane, DeKalb, Ogle, Bureau, and Henry in northern
Illinois; Woodford, DeWitt, Sangamon, and Montgomery in cen-
tral Illinois; and Marion in the southern part of the state. Doubt-
less the actual area infested by it was much more general than this
list would indicate.

The injurious effect of a severe and long-continued drain by the
cottony maple scale on the vitality of trees infested by it is unques-
tionable. Many thousands of soft maple, linden, box-elder, and elm
trees in northeastern Illinois are now dead or dying, or have been
disfigured by the death of large branches, because of injuries by
this insect, and large numbers of such trees have been removed. Pri-
vate citizens, town boards, and park commissioners have become
deeply concerned, and numerous inquiries and appeals for aid have
come to this office during the past three years. A lack of available
funds has, however, prevented as active a participation in the work
of practical experiment and insecticide operation as might reason-
ably have been expected of the Entomologist’s office, and I have
been obliged to content myself, in the main, with improving the
opportunity to observe, and incidentally to assist, the work of official
bodies and private parties for the control of this pest.

I am particularly indebted to Mr. Reuben H. Warder, Superin-
tendent of Lincoln Park, who has kept me acquainted with his work
against this and other scale insects, and has made it possible for us
to follow his operations in detail to their final results. I am also
under obligations to Mr. O. C. Simonds, Superintendent of Grace-
land Cemetery, for similar privileges. Our field observations have
been mainly made by Dr. J. W. Folsom, Associate in Entomology
at the University of Illinois, and by Mr. E. O. G. Kelly and Mr.
C. A. Hart, serving as assistants to the State Entomologist. Dr.
Folsom also managed a small spraying experiment for me at Grace-
land Cemetery in 1905.

The present article, in the preparation of which I have had the
valued assistance of Mr. Hart, is intended to give a brief account of

103

the insect, to review the attempts made to destroy it by means of
summer and winter sprays, and to present practical instructions
for its mastery where it is still present in destructive or threatening
numbers.

A comprehensive article on the insect, prepared by Dr. L. O.
Howard, appeared in 1900 in Bull. 22 of the U. S. Bureau of En-
tomology, and Circular 64 of that Burean gives a brief popular
account of it and of measures to be taken for its destruction. This
paper was prepared with special reference to the Chicago situation
of 1905. In Bull. 52 of the Bureau, published in 1905, is a paper
by Mr. H. E. Weed describing his experiences in spraying against
this scale in Chicago, and Mr. S. A. Johnson has reported on some
experiments in Denver, Col., with a winter insecticidal treatment.
The last-mentioned author has this year made the species the subject
of Bull. 116 of the Colorado Agricultural Experiment Station, in
which a summer treatment is especially discussed.

Foop PLANTS.

- The soft maple (Acer saccharinum) is the tree most generally
and heavily infested by this insect. The hard maples, on the other
hand, are infested but slightly if at all. The box-elder is also greatly
subject to injury, and next to this, perhaps, the linden or basswood.
Among the other trees and woody plants often more or less injured,
are the elm, honey-locust, black locust, black walnut, sumac, willow,
poplar, beech, hawthorn, bittersweet, grape-vine, and Viriginia
creeper. Dr. Folsom found mature egg-laying females on the horse-
chestnut, honeysuckle, dogwood, trumpet-creeper, mulberry, snow-
berry, smoke-tree, Spirzea, false syringa (Philadelphus), and Wis-
taria. Oak, ash, and catalpa are not infested in northern Illinois,
but injury to oak is reported from Georgia. According to S. A.
Johnson, the pear is most liable to injury among the fruit-trees, and
apple, plum, and peach are sometimes infested. Serious damage to
fruit-trees is, however, very unlikely. The migrating young, which
are often washed from trees by rain, or blown off in considerable
numbers, may maintain themselves for a time on a great variety of
woody and herbaceous plants, those on the latter, of course, per-
ishing with the advent of frosts.

104

THE LiFe History OF THE INSECT.

In early summer this
scale, when very abund-
ant, coats the under
side of heavily infested
limbs with a_ thick
layer of cotton-like
waxy masses (Fig. 1,
2), each projecting
from beneath a brown
cap or scale—the flat
body of the mature fe-
male. This “cotton’’ is
secreted and the eggs
are deposited within it
in late May or early

Fic. 2. The Cottony Maple Scale, adult females 1 ;
on twigs. Natural size. (iomard, U.S. Department of June in the latitude of
Agriculture.) central Illinois, but usu-

ally one or two weeks later in the Chicago district.
Something over 3000 eggs are usually laid by each female, the
number ranging, in our counts, from 2856 to 3863, with an aver-

oy “

Fic. 3. The Cottony Maple Scale, immature stages: a, newly hatched young, under side;

é, c, young female, top and side views; d, young male; e, f, young on leaf and leaf-stem. Natu-
ral size shownine. (Howard, U.S. Department of Agriculture.)

age of 3410. ‘These eggs ordinarily hatch in June in central IIli-

nois, in early July in the northeastern part of the state, or later if

the weather of the time is unfavorable. Virtually all are hatched,

as a rule, by the end of July. The young insects may crawl out on the

leaves and establish themselves beside the principal veins on both

105

surfaces of the leaf, but most abundantly*beneath, or else may locate
upon the twigs. At this season (Fig. 3) they present the appear-
ance of small, inconspicuous, waxy, elongate-oval scales, applied
closely to the leaf. They are usually motionless, but have never-
theless minute
legs still capable
of service, but in-
visible unless the
insect is turned
over. Inserting
their tiny beaks
into the tissue of
the leaf, they suck
out the sap, and
when the supply
of food is large
they give off the
excess in the form
of a sticky fluid,
the so-called
“honey dew,”
Pr eee Peace OES pee eh @ adult; Bes anan- W hich moistens
skin; f, 2, ae eee ile eepeen guia. Alt eeeaty Barren the surface of the
(Howard, U. S. Department of Agriculture.) lower leaves and
falls on the plants beneath the tree. Under this
large and constant withdrawal of sap the leaves
turn pale or yellowish, and may fall off prema-
turely, with the effect sometimes to kill the larger
branches or even the entire tree.

The male bark-lice beneath the scales on the
leaves reach maturity the same season, and trans-
form to tiny gnat-like insects (Fig. 4) with a
pair of delicate wings. They pair with the partly
grown females on the leaves, and die at the ap-
proach of winter. Before the fall of the leaf in
autumn the young females collect on the under
side of the smaller branches, where they spend
the winter in a more or less dormant condition
Maple Stalesaduit fe, With their beaks inserted in the wood. ‘They
pate tee aitst complete their growth in spring (Fig. 5), and
(Howach U.S 3c. in due time produce the so-called “cotton,” within
partment of Agricul: which the eggs are imbedded.

106

TE HatcHINc PERIop.

As the newly hatched young are especially susceptible to the
petroleum insecticides, which act by contact, a definite knowledge
of the hatching period has an important practical value. In central
Illinois this period extends approximately from June 15 to July 20.
In and about Chicago it commonly begins about two weeks later,
and continues for a period of three weeks, this retardation being ap-
parently due to the higher latitude and to the neighborhood of Lake
Michigan. In 1905, for example, Dr. Folsom found that the young
began to appear in Chicago about July 1, and were all out by
July 21 or a few days later, but that thirty miles west of the
city, hatching began about June 20. Mr. H. E. Weed reports, in
Bull. 52 of the U. S. Bureau of Entomology, that in 1904 scarcely
any eggs had hatched in Chicago by June 25, but that the young ap-
peared rapidly under the influence of a few days of warm weather
about July 10. The recorded dates for Colorado approach those
given for Chicago. In Washington, D. C., according to Dr. How-
ard, hatching of the eggs begins usually in late May or early June,
and continues into July and sometimes to the beginning of August.

The period varies, in short, as to its beginning time, with the
advancement of the season, and once begun, the rapidity of the
hatching will depend, other things being equal, on the warmth of
the weather. It is also influenced locally by the amount of foliage
on the trees, the eggs hatching later and more slowly in a dense
tree-top than in one more open to the sun.

SUMMER INSECTICIDE MEASURES.

Owing to the manner in which these insects obtain their food—
that 1s, by sucking the sap through a tubular beak—they are not
susceptible to poisoning by way of their food, and the only insecticides
available against them are those which kill by contact, and of these
the kerosene mixtures have thus far been found the most useful.
The most ‘satisfactory of these is the common kerosene emulsion,
made by thoroughly and intimately mixing a good grade of kero-
sene with one third its volume of a strong soap-suds, and diluting
with water according to the time of the year when used. Precise
directions for preparing and applying this emulsion may be found in
the general summary at the end of this paper.

The use of this insecticide for the maple scale dates from experi-
ments made by me in 1884, intended to test the effect of kerosene
emulsion on the newly hatched young, and described in the Four-
teenth Report of the Illinois State Entomologist. They showed

107

that practically all these may be killed by dipping the infested
leaves in dilute emulsions (those used varying in content from 2%
to 10 per cent. of kerosene), unless the application be delayed too
long after hatching. When the young are a week or two old they
are partially protected by a waxy covering against the action of the
oil. The test of death used was a thoroughly reliable one. The
young were at this time so small and transparent that the action of
the heart could be readily seen under a microscope, and the cessation
of this action was the mark of death depended upon. As the maple
scale disappeared from my neighborhood in 1885, no further experi-
ments were made at that time.

In 1904 the Commissioners of the North Shore Park District,
above Chicago, of which Robert W. Vasey was president, engaged
Mr. H. EF. Weed, of Chicago, to treat one hundred and twenty soft
maples and box-elder trees in their charge, along the boulevards, for
the destruction of the cottony maple scale. A report of this treat-
ment by Mr. Weed was printed in Bull. 52 of the U. S. Bureau of
Entomology. The results of his work were submitted to me for
examination in August and September, 1904, by Mr. Vasey, who
sent me leaves from the trees which had been treated with a 12 per
cent. emulsion.

The scale insects on these leaves were carefully examined at
my office by Mr. Hart, who found that out of 1781 scales 610 were
alive and 1171 were dead.* Practically all the living scales were on
the under surface of the leaves, only I per cent. of those on the upper
surface being still alive. The ratio of the dead to the living on these
leaves was 60 per cent. ; but as it seemed likely that some scales were
dead before the spray was applied, Mr. Vasey sent me, for com-
parison, at my request, leaves from infested trees not treated. An
examination of these untreated leaves showed that 22 per cent. of
those on the upper surface were dead and 4 per cent. of those on the
lower surface. Making the necessary correction, it was found that
57 per cent. of the scales alive when the trees were sprayed had been
killed by the treatment. The spray thus tested was applied Au-
gust 20.

According to Mr. Vasey, the insects had hatched very slowly
that year, owing to the backward season, but had been in condition
for treatment with the kerosene spray for some three or four
weeks preceding. It will be seen, consequently, that the treatment
was too late to produce the full effect upon the young. Further

*The young insects were by this time so opaque that the movements of the heart could
no longer be seen; but it was found that living individuals, when displaced and inverted,

made slow movements of the legs, and that dead individuals were not only motionless but
paler and often discolored, and usually more or less dried up.

108

work showed that a 15 per cent. emulsion was injurious to the tree,
taking nearly all the leaves from the box-elders and the lindens, and
half those from the soft maples. In this same year (1904) Mr. S. A.
Johnson, of the Col. Agricultural Experiment Station, made a num-
ber of laboratory experiments with the summer treatment of this
insect, reaching the conclusion that after the young are a week or
ten days old they are not easily killed by the kerosene emulsion, but
that before reaching this age they may be effectively treated by
sprays of as low a strength as 5 per cent.

The following year (1905) Dr. J. W. Folsom, of the University
of Illinois, made for me a series of experiments, opportunity for
which was provided by the courtesy of Mr. O. C. Simonds, Super-
intendent of Graceland Cemetery. .

A Io per cent. emulsion of kerosene was applied to several trees
of medium size with the use of a Bordeaux nozzle on an extension-
pole. A solid stream was first directed against the egg-masses in order
to loosen and soak them, after which a very fine spray was applied
as thoroughly as possible to both sides of the leaves. A solution of
whale-oil soap (one pound to six gallons of water) was applied to
an eighth tree by the same apparatus and with the same care.

The effect of the spray was tested by counting both dead and
living scales on twenty-five leaves picked at random from different
parts of each tree, one series of counts being made just before the
spray was applied and another as soon as possible after it had dried
away and taken effect. Among the trees receiving the 10 per cent.
emulsion of kerosene were one tree sprayed July 3, at the beginning
of the hatching period of the scale, one treated July 11, at about
the middle of this period, three treated July 19 and 20, at the end
of the period, and one treated twice, once at the middle and once at
the end. The tree receiving the soap solution was sprayed July 19—
that is, at the end of the hatching season.

Four hundred and eighty-four thousand scales, borne by four
hundred and fifty leaves from these various trees, were critically
examined, and classified as either living or dead. The ratio of bene-
fit—the percentage, that is, of scales actually killed by the spray—
was determined in all cases by eliminating from the calculation the
scales dead at the beginning of the experiment, and figuring the per-
centages only on the number of scales alive when the spray was ap-
plied. The following table gives the essential data and results of
these experiments.

109

EFFECTS OF EXPERIMENTAL SUMMER SPRAY.

Treatment
Leaves | Scales |Percent.
Part of |No.of; gy. ex- killed
Insecticide hatching |*T€€S| amined | amined |by spray
period
10 per cent. Kerosene Beginning} 1 15 48,789 33
10 per cent. Kerosene Middle 1 50 19,425 64
10 per cent. Kerosene. End 3 150 281,271 68
10 per cent. Kerosene ee 100 57,179 82
and end
1 1b. Whale-oi
Pa eae End 1 15 | 77,171 43

6 gal. water

From this it will be seen that 75 leaves bearing 49,000 scales
were examined from the tree sprayed July 3, and that only 33 per
cent. of the scales on this tree had been killed. In this case a first
inspection was made ten days after the spray was applied, and a
second, seven days later. The trees sprayed once July 11—at the
middle of the hatching period—and from which 50 leaves bearing
19,000 scales were examined, showed a ratio of benefit of 64 per cent. ;
that is, 64 per cent. of the scales alive when the spray was applied,
were dead a few hours later. In other words, by postponing the
treatment from the 3d to the 11th of the month the effect of it had
been nearly doubled. A similar but somewhat greater effect was
produced by single treatments given July 19 and 20, when the
greater part of the eggs were already hatched, 68 per cent. of the liv-
ing scales among the 281,000 borne by the 150 leaves examined being
thus killed. The most effective treatment was a double spraying,
one application at the middle and the other about the end of the
hatching period, which, as shown by an examination of 57,000 scales
from 100 leaves of the tree so treated, killed 82 per cent. of the
scales alive when the tree was sprayed. ‘That is, the effect of the
operation had been increased approximately 28 per cent. by the sec-
ond spraying.

A comparison of the scales on the two surfaces of the leaves
showed that the ratio of those killed on the lower surface was only
72 per cent. that of those killed on the upper surface. This was doubt-

110

less due in part to the fact that the upper surface of the leaf is more
exposed to the spray than the under, and possibly also in part to the
inferior vitality of the scales on the more exposed surface of the
leaf. That there is really such a difference is shown by the differ-
ence in ratios of dead to living on the two leaf surfaces before the
trees were sprayed. The general average of all the counts is 3.6
per cent. of dead on the upper surface of the leaf and 2 per cent. on
the lower.

In the tree sprayed July 3 the effect on the scales on the upper
and the lower parts of the top of the tree was brought into compar-
ison by examining the scales on 25 leaves from each. Twenty-two
per cent. of the scales on the upper leaves had been killed and 35 per
cent. of those on the lower, the ratio of killed being more than half
as great again for the lower leaves as for the upper. ‘This is doubt-
less due, at least in part, to the greater and more prolonged effect
produced on the lower leaves by the drip from the upper part Of the
top.

We may infer from these experiments that two sprayings with
a 10 per cent. kerosene emulsion, one applied at the middle and the
other at the end of the hatching period, separated, that is, by an in-
terval of about ten days, will produce the maximum effect on the scale,
and that they may be expected to destroy 80 per cent. or more of the
insects then alive. It should be added that no harm to the tree was
done by any of these treatments except a slight burning at the edges
of the leaves of the tree which was twice sprayed. This appearance
of injury was perhaps due to humid weather which followed the
first treatment, delaying the evaporation of the kerosene. ‘T'wo trees
were treated July 11 with a 10 per cent. kerosene emulsion, at a
time and place when rain was falling with a result to diminish by
half the killing effect of the spray.

The cost of che 10 per cent. emulsion used in these experiments
was 4.3 cents per gallon, and the trees were large enough to require
three or four gallons each for a single treatment.

The whale-oil soap solution applied at the end of the hatching
period had about two thirds the effect of the corresponding kerosene
treatment, as shown by a comparison of the results of the data
already given for the latter with those derived from an examination
of 77,000 scales on 75 leaves taken from the tree treated with the
former insecticide.

WINTER INSECTICIDE MEASURES.

Winter spraying, when the trees are bare, has the advantage
that stronger insecticides may be used, and that less than half as

111

much liquid is needed to the tree. On the other hand, the scales are
now larger and firmer and more resistant to the insecticide than in
summer.

The extensive operations against this scale by the Superintend-
ent of Lincoln Park during the winter of 1905-06 were followed by
one of my assistants, Mr. F.. O. G. Kelly, sent repeatedly to Chicago
for this purpose. Nearly every tree and shrub in this park infested
by the maple scale was sprayed under the immediate supervision of
Mr. R. W. Braucher. Two thousand six hundred and seventy-three
trees and 4456 shrubs were sprayed, nearly half the trees ranging
from large to very large, and the remainder from small to medium.
The materials used in this treatment were 4153 gallons of kerosene
and 3074 pounds of soap, made up in 20,800 gallons of kerosene
emulsion. The cost of the latter was approximately 2 cents a gallon.
With the outfit used, a Fairbanks-Morse power sprayer with double
“Vermorel”’ nozzles, it required, on an average, five minutes to spray
each tree, or an hour for twelve trees. Eight men were employed
with the outfit, making an average service of forty minutes of one
man’s time per tree. Six and seven tenths gallons of emulsion were
applied to the average tree, at a total cost of 43 cents for both ma-
terials and labor.

In spraying operations, ladders and long canes were used in or-
der that all parts of the larger trees might be reached by the spray.
In the greater part of the work 19 and 20 per cent. emulsions of
kerosene were applied. To make this up in 200-gallon lots, 20 gal-
lons of water and 27 to 30 pounds of “Tak-a-nap” soap were placed
in the mixing tui, and steam was introduced until the soap was dis-
solved and the solution was boiling hot. Forty gallons of kerosene
were then slowly pumped into the tub, and the mixture was pumped
back into itself until the kerosene no longer rose to the surface when
the pumping ceased. The emulsion was finally diluted by adding
hot water to make 200 gallons.

A part of the trees examined were sprayed between December
26 and January 5, and others January 11 and 13 and March 30.
The effects of the spray were determined by comparing ratios of
dead and living scales on trees which had been treated, with those
from others examined at the same time which had received no
treatment. A determination of the condition of the scales subse-
quent to treatment was a much more difficult matter at this season
than during the summer. The dormant insects themselves were
comparatively large and dense, and changes due to death were pro-
duced but slowly in the cold midwinter weather. From twenty-

112

seven to forty days actually intervened between the time of spraying
and the time when the test inspections were made.

It will be sufficient to say, without entering into details, that a
critical examination of 13,000 scales taken from 8 trees showed that
86 per cent. of them had been killed by a 19 per cent. emulsion; and
an examination of 23,000 scales taken from 11 trees which had been
treated with a 20 per cent. emulsion showed that gI per cent. of these
had been killed. Seven trees, two of which had been sprayed Janu-
ary I1 and five March 30 with emulsions containing from 19 to 24
per cent. of kerosene, were examined June 10, 49,000 scales in all
being counted, with the result to show that in this case, also, 91
per cent. of those alive when the treatment was applied had been
killed by the emulsion. The trees covered by these observations
were soft maples, lindens, and honey-locusts, but as the percentages
of benefit do not differ materially for these different species they
need not be separately given. The following table summarizes
these data. :

Per cent.| Date of Scales |Percent.

When sprayed of count- :
kerosene| ing cone Rages killed
December 26 to January 5 19 Feb. 1 12,703 | 86
January 11 to 13 20 Feb. 1-2 23. OGRA +, ol
January 11 to 13 and March 30 19-24 |June 10 48, 395 | 91

INJURY TO TREES.

As one of the results of an examination of trees previously
sprayed, made by my inspector June 11 to 13, he reported so serious a
damage to some of the trees as to cast doubt on the safety of the kero-
sene spray. At Graceland Cemetery, for example, some soft maples
had received during the winter an experimental treatment with a 25
per cent. kerosene emulsion, evidently prepared in the usual way, and
all these trees were in a conspicuously poor condition, with foliage
thin, pale, and shriveled, while that of unsprayed trees among them
was heavy and dark green. Many of the trees in Lincoln Park on
which an emulsion containing 19 or 20 per cent. of kerosene had
been used, presented the appearance of a similar, although less seri-
ous, injury. A few, indeed, were dead, and dead branches were
more numerous on others than usual.

After a study of the report of my own inspector, Mr. E. O. G.
Kelly, on the condition of these trees last June, and a full and care-
ful report on the same subject made to Superintendent Warder by
Mr. R. W. Braucher, in charge of the spraying operation, and an
examination of comparative photographs, made under Mr. Brauch-

113

er’s direction, of trees of various species—some of which had been
sprayed and others of which had not—it seems to me clear that
many of these trees were already in a more or less enfeebled state
owing to the light and sandy soil and other unfavorable conditions
affecting their growth, that many treated trees had been further
greatly weakened by heavy and continuous infestation by the maple
scale, and that the consequences had been in some cases intensi-
fied by the action of the kerosene. This is especially suggested by
the fact that trees seemingly most injured but not actually killed,
presented the same general appearance—though in a more marked
degree—as many of those which had not been sprayed at all. Pre-
cise and extensive experiments, the results of which may be brought
into strict comparison, are needed to show the strength and the
amount of the emulsion which it is safe to use under various con-
ditions and on various kinds of trees.

In the meantime, in view of the fact that the thorough spraying
of the top of a tall tree in winter requires a large amount of kero-
sene emulsion, much of which must fall to the earth, and the further
well-known fact that fruit-trees may be severely injured, and even
killed, by kerosene in the earth about their roots, it will be prudent
to protect the ground where this insecticide is used by some imper-
vious or absorbent covering, such as a sheet of canvas or a layer of
straw, the latter afterwards to be removed. Kerosene will, in fact,
remain effective in the ground for a surprising time, and this fact
is the basis of one of its most important uses as a subterranean in-
secticide.* Thousands of fruit-trees have been destroyed within my
own knowledge, by its careful use under the supervision of expert
operators, where orchards were undergoing treatment for the San
Jose scale.

Experiments already referred to, made at Denver, Col., by Mr.
S. A. Johnson, resulted in a way to indicate that weaker emulsions
than those used in Chicago may be depended on to destroy the maple
scale, as shown by the following table.

Percentage of emulsion} 10 bin ee 0, a ee Wf 20 25 33 50
November, 1908 . 88 88 100 100
February, 1904 69 94 99 98 | 100 | 100

= *The most notable instance of this persistence of kerosene in the earth which has come
to my knowledge is reported to me by Professor T. J. Burrill, of the University of Illinois,
who, in company with Prof. J. C. Blair, of the Horticultural Department, once lightly sponged
the bark of a pear-tree with pure kerosene as au experiment. Nothing unusual was noticed
the first year, but the second year the tree was seen to be unthrifty, and the third year it was
dead. When dug up to learn the cause of its death, the odor of kerosene was still distinct and
strong in the earth among its roots, and especially in the bark about the base of the trunk.
The surplus which had run down the surface of the bark and sunk into the soil had remained
all this time, acting, no doubt, continuously upon the rootsand on the bark of the trunk ina
way to kill the tree.

114

On the strength of these experiments Mr. Johnson recommends
an emulsion one sixth of which is kerosene. ‘Trees treated with an
emulsion of this strength in the winter of 1904-05 were nearly free
from scales the following July, and in January, 1906, only scatter-
ing specimens could be found. In view, however, of the difference
in climate and the absence of data as to parasitism, these results
should not be regarded as conclusive for Illinois.

INSECT ENEMIES.

It is to the insect enemies of the scale rather than to any human
agency that the escape of our soft maple trees from complete de-
struction has hitherto been due. Probably the most effective enemy

FiG.6. Coccophagus lecaniz, adult chalcid parasite of the cottony maple scale.
Length, less than ), inch. (J.B. Smith.)

is a minute black four-winged fly (Coccophagus lecanii, Fig. 6)
which lays its eggs in the bodies of the young scales. The resulting
larva lives as an internal parasite of the insect, develops to the adult,
and emerges through a rounded hole cut in the back of the scale. Suc-
cessive generations follow, and the scale population of a heavily in-
fested tree may be almost completely destroyed in a single season
by the parasite. Scales killed by it may be readily recognized by
the hole in the back, and by their smaller size as compared with
living individuals. Several other related species are known to infest
this scale to a less degree.

115

A conspicuous and very efficient
enemy is a small hemispherical lady-
bug (Hyperaspis binotata, Fig. 7)
about an eighth of an inch long, jet-
black, with a small dark-red spot on
each side of the middle. It is often
seen on the leaves of infested trees
and on plants beneath. The white
thick-bodied larve of this species

=

Bet Aehae rope asp bs (Fig. 7,d), which feed on the eggs
tata, enemy of cottony maple scale: a, of the scale may often be found
adult; d, larva; 6,c,antenna and palpus x : ? :
of adult. Adult about 7 as long as Chz- buried in the egg-mass or crawling
locorus bivulnerus, similarly colored; 2

larva, white. (Sanders, U.S.Department gbout on the twigs. The pupa of
of Agriculture.) : : “nL:

this ladybug is formed within the
cottony egg-mass, and soon changes to the adult. The beetles pass
the winter wherever they may find shelter about the tree or on the
ground beneath. ‘he larger but similarly-colored “twice-stabbed
ladybug” (Chilocorus bivulnerus, Fig. 8), with its black spiny
larva, also destroys many maple scales.

fi 3 9 |
Fic. 8. A Ladybug, Chilocorus bivulnerus, larva, pupa, and adult, enemy of cottony
maple scale. Natural size indicated at right; color black, adult with two red spots.
(Comstock, U.S. Department of Agriculture.)

SUMMARY.

1. Injuries by the cottony maple scale are commonly periodical.
A period of destructive abundance and following scarcity extends,
on an average, over eight or ten years, the disappearance of the in-
sect being apparently due in the main to depredations by its insect
enemies.

2. A partial exception to the foregoing statement is presented by
the existing outbreak in northeastern Illinois, and especially in Chi-
cago, where the maple scale has continued injurious for at least six
years, and gives no marked present evidence of a general decline in
numbers.

116

3. The area injuriously, infested by this insect in Illinois last
year covers parts of at least fifteen counties, distributed throughout
the state from the Wisconsin line to Marion county.

4. The chief food plant is the soft maple, but linden and box-
elder are almost equally liable to infestation. The elm and the
honey-locust are the principal other ornamental trees subject to
serious injury.

5. There is but one generation of this insect each year. The fe-
males pass the winter partly grown on the twigs of trees, and pro-
duce eggs in late May or in June, according to the latitude and the
weather of the season. These eggs hatch in June and July, the
young insects establishing themselves for the summer on the leaves
or twigs, from which they suck the sap. ‘The males emerge as
winged insects, and perish at the approach of winter. The females
at that time collect on the twigs and smaller branches for hibernation.

6. The most useful insecticide is kerosene emulsion, which, if
used in summer, should not contain more than 10, or possibly 12%,
per cent. of kerosene, and, if used in winter, not more than 16 to 18
per cent. As a summer spray this emulsion must be used twice in
succession, with a ten-day interval between sprayings. ‘The first
application must be made when about half the eggs are hatched, and
the second at about the end of the hatching period. Two treatments
with 10 per cent. kerosene, applied to badly infested trees in Chi-
cago, the first July 11 and the second July 20, 1905, destroyed 82
per cent. of the scales; a single treatment July 11 destroyed 64 per
cent.; and one July 19, 68 per cent. A similar treatment July 3,
on the other hand, killed but 33 per cent. of the insects.

7. A single treatment in winter with a 19 or 20 per cent. emul-
sion destroyed more scales than two summer treatments with a 10
per cent. emulsion, the percentages of killed varying from 86 to
Ol per. cent:

8. Where large trees weakened by unfavorable conditions or by
insect attack are treated with strong emulsions in winter, they are
liable to injury by a penetration of the kerosene to the roots. Such
trees should be protected, consequently, by covering the earth be-
neath the trees with sheets of canvas or layers of straw, or some
similar absorbent substance.

9. Kerosene emulsion is made as follows: Dissolve one pound
of common soap, or half a pound of whale-oil soap, in one gallon of
water by boiling, remove from the fire, and add two gallons of kero-
sene. ‘Then with a spray pump force the mixture back into itself
for about five minutes, or until it presents the appearance of a thick
cream and no longer separates on standing. ‘This is the undiluted

Pruate V. Sorr Mari& TREE SPRAYED WITH 20 PER CENT. KEROSENE EMULSION
JANUARY 19, AND PHOTOGRAPHED JUNE 23, 1906.
ORIGINALLY A SOUND TREE.

Puate VI. Sorr Mapte Tree SprayeD witH KEROSENE EMULSION JANUARY 18, AND PHOTOGRAPHED JUNE 23, 1906.
ORIGINALLY WEAK, WITH TRUNK AND LARGER LIMBS DECAYED AND HOLLOW.

Puate VII. Box-Euper TREES, NOT SPRAYED. PHOTOGRAPHED JUNE 23. WEAK
TREES WITH MANY DEAD BRANCHES.

Te oa

1

emulsion. For a mixture containing 10 per cent. of kerosene, add
seventeen gallons of water to the three gallons thus prepared. For
an 18 per cent. kerosene emulsion, add eight gallons of water to the
stock solution. Soft water is to be preferred.

10. The principal insect enemies of the cottony maple scale are
minute winged parasites which lay their eggs within the bodies of
the female parents; and hemispherical shining black ladybugs, each
with two red spots on the back, the larve of which devour the eggs
in spring within the cottony masses beneath the female body.

118

THE ELM TWIG-GIRDLER
OBEREA ULMICOLA CHITTENDEN:

In October, 1901, Mr. E. S. G. Titus, an assistant in my office
at the time, was told at Decatur, Ill., by Mr. Frank Torrence, in
charge of the parks of that town, that the common white or Ameri-
can elm-trees* there had been injured during the last three or four
years by an amputation of great numbers of small twigs in June.
Tufts of three to five or six leaves, each borne by a twig which had
been cut squarely off, as if by a knife, would fall so thickly that in
places the ground was nearly covered by them under the larger
trees.

In consequence of a letter from Mr. E. A. Gastman, Superin-
tendent of Schools at Decatur, written me May 10, 1902, reporting
that this injury was just beginning for the season, Mr. Titus went
to Decatur again on the 22d of May for a careful investigation of
the subject. A considerable number of large elms in the city square
(commonly called Central Park) were then being injured by some
insect which was cutting off the young twigs, each bearing from
two to seven fresh leaves. Other twigs, similarly injured but not
yet detached, were found on a young elm-tree, beneath which were
about twenty-five fallen leaf-clusters.

Among the insects noticed at the time was a species of Oberea
gnawing away the veins on the under side of the leaves. No eggs
were found on or in the twigs at this visit, but three females and
two males of this Oberea, taken from an elm, were placed May 23
with twigs of that tree in a portable breeding-cage, carried about
by Mr. Titus while he was traveling for the office. Two eggs found
in a fresh elm twig in this breeding-cage May 24, four more May
28, and two May 209, together with a newly hatched larva found in
one of these twigs May 30, made plain the cause of the injury.

Later visits to Decatur by Mr. Titus, by Mr. F. M. Webster
and by Mr. E. P. Taylor, together with breeding-cage observations
and field and insectary experiments, have given me the materials
for a fairly full account of this insect, especially interesting because
of its power of injury to our most important shade tree, and also
because it has lately been found infesting the cherry, and, in one
case, the peach.

*Ulmus americana,

LAS)

The only previous mention of this species is contained in an
urticle prepared at my request by Mr. Webster, (in my office at the
time, ) and published in the Bulletin of the Illinois State Laboratory
of Natural History* in February, 1904. In this article the species
is described by Chittenden under the name of Oberea ulmicola, and
the main facts are reported so far as observed up to that time.

RECOGNITION OF THE INJURY.

The presence of this insect may be suspected when the tips of
small twigs of the elm, each bearing a few fresh leaves and cut
squarely off at the base, fall from the trees between May 20 and
June 15. A careful examination of the stubs remaining on the tree
where these twigs have been cut off, will show a narrow encircling
groove or girdle cut through the bark at two inches or less from
the blunt end, and a small L-shaped slit between this girdle and the
end of the stub. On other twigs which have not yet lost their tips,
two girdling grooves may sometimes be seen, about two inches
apart, with the L-shaped slit between them, and in this case the tip
of the twig may be readily broken off at the groove nearest the end.

If a tree has been considerably infested the preceding year, dead
stubs, single or clustered, may be seen here and there on the
branches, with younger twigs springing up among them and still
alive. Repeated injuries of this description, year after year, give
the tree a scrubby and unwholesome look, and may even kill it
eventually, after forcing it to put forth new twigs repeatedly, as
the growth of the preceding season is destroyed.

The insect doing this injury is a slender, cylindrical, hard-
shelled beetle, about half an inch long, with head and body black
above, except the thorax, which is yellow with two round black
spots near the middle. The color beneath is mainly yellow.
(PI. VIII., Fig. a.) The female lays her eggs, one in a place,
usually under a triangular flap of bark made by the intersection of
the lines of an L-shaped slit.

The slender larva of this beetle (Fig. c) lives within the injured
twigs, which it burrows lengthwise, pushing its excrement out
through small round holes made in the bark for the purpose. It is
about half an inch long when full grown, light straw-colored, a lit-
tle darker at the ends. ‘The pupa (Fig. d) is formed in the larval
burrow.

*Vol. VII., pp. 1-13.

120

NATURE AND EXTENT OF THE INJURY.

Under a badly infested tree, hundreds of fallen twigs, bearing
four to six leaves each, may be found in May and June. Sometimes
twigs are cut off not more than a half or three quarters of an inch
long, each bearing only a single leaf; and occasionally those ampu-
tated are a foot long, with a dozen leaves or more.

When the beetles become superabundant, a female frequently
girdles the stub of a twig below the point where an egg has been
previously placed by another beetle, thus causing the part contain-
ing the first egg, or the young larva hatching from it, to fall to the
ground. She then places her own egg in this second stub. Five
per cent. of the twigs collected May 29, 1903, had been used a sec-
ond time in this manner. Later in the season these amputations
were sometimes repeated five or six times on the same twig.

If the tree is very heavily attacked, the fallen leaves may nearly
cover the ground in early June. Under eighteen trees in the city
square of Decatur, there were picked up on the 7th and 8th of June,
1905, 11,986 twigs, measuring six bushels when closely packed.
Seven hundred were collected beneath one tree on the 4th of June.

The effect on the trees is to destroy the young twigs put forth
prior to the middle of June, and this injury, continuing year after
year, results in bunches of dead stubs distributed all through the
top. The trees become stunted, scraggy, and misshapen, with the
leaves growing in tufts on the larger limbs. The younger trees lose
their spreading habit, and grow upright with narrow ragged tops.
The larger ones are less affected, but are injured in appearance by
the loss of foliage, and by clusters of dead stubbed twigs seen every-
where through the tops. A tree in Central Park, about forty feet
high, had been so seriously injured in 1904 that by May 3 of the
following year only a few leaves had appeared, although uninjured
elms were thickly covered with half-grown foliage. Large branches
of this tree, which had previously sent out many clusters of sec-
ondary twigs, were now dead. On one branch, about the thickness
of a finger, killed by girdlers the preceding year, nineteen truncated
stubs were counted within a length of fourteen inches. Another
tree, thirty-five feet high, was so injured that it would probably die
before another season. Only a few leaves had appeared by the 5th
of May, and these were in the center and at the top.

In Decatur, where this insect was first discovered and has been
chiefly studied by us, the elms of the greater part of the city were
infested in 1905, as was shown by a general survey made by Mr.
Taylor in May and June. The infestation had not yet reached Fair-

121

view Park, nor the grounds of Millikin University, in the outskirts
of the town. ‘The slow spread of the beetles was shown, not only
by their destructive abundance in some parts of this town and their
virtual absence in others, but also by the fact that of trees standing
side by side some showed scarecly a trace of injury while others
were badly damaged. ‘The beetles can fly vigorously, and were
sometimes seen on the wing; but they seem to lack the dispersal
instinct—a fact the more remarkable because they are extremely
intolerant of each other’s company, both males and females attack-
ing each other ferociously and devouring one another so readily
that they can not be kept together in confinement.

The injury to the elm begins late in May. On the 23d of that
month in 1902 a few fallen twigs bearing fresh leaves were first
noticed at Decatur, and others recently girdled but not yet fallen
were seen on the trees. It is most abundant early in June, com-
monly from the 1st to the 5th, and may continue to the 24th of that
month, after which date, in 1905, it was practically over for the
season. It was noticed by Mr. Titus that rains and cool weather
stopped the work of the beetles, sometimes for two or three days
at a time.

Besides its injuries to the common American elm (Ulmus
americana), this insect was seen at Decatur infesting, in the same
way, cherry-trees, both sweet and sour, and it was once found in a
peach-tree at the same place. Red elms, on the other hand, grow-
ing among badly infested white elm-trees, showed no traces of the
attack, and raspberry plants, liable to infestation by another species
of the genus, were absolutely refused by beetles of this species kept
in confinement and offered no other food.

Experiments made by Mr. Titus in May, 1903, showed that
this beetle will not breed in either dogwood stems or raspberry
canes. For example, three pairs of specimens, male and female,
which had been bred at various dates from elm twigs, were placed
May 20 on a growing raspberry plant out-of-doors under a bell
jar. The beetles were noticed pairing, but May 29 all were
dead, leaving no trace of eggs or preparations for their deposit on
the plants, and no evidence of any attempt to feed on the leaves
except a little gnawing of the midrib of one leaf. When beetles
were shut up under glass with twigs and leaves of the elm the in-
sects fed and bred quite as freely as if at large.

122

LiFE History AND Hapits,

There is but one brood of this insect in a year, and it passes the
winter as a larva in the stubbed twigs remaining on the tree. It |
pupates from the middle of April to the last of May, within the
larval burrow, the outer end of which is closed by a wad of chewed
wood, and here also the pupa changes to the adult, beginning about
May 10. ‘The beetle does not eat its way out of the burrow, but
escapes by pushing out the terminal plug of the hollowed-out twig.
Pairing and egg-laying follow, from about May 20 to the 10th of
June, accompanied by the amputation of twigs as already noticed.
The beetles, male and female, die soon after the eggs are laid, and
all are gone by the last of June.

Mode of Oviposition.—It was observed by Mr. Titus in tg02
that the female beetle first girdles the twig by cutting with her jaws
a groove entirely around it so deep that the twig is readily broken
off. Below this she then cuts a longitudinal slit about an eighth to
a fifth of an inch in length through the bark but not into the wood,
and at the lower end of this she makes a shorter transverse slit,
sometimes to the right and sometimes to the left, also merely
through the bark. She now pushes the tip of her abdomen under
the bark at the angle formed by the two slits thus made, and places
her egg under the flap, where it can easily be detected by the slight
elevation thus caused. She next retreats still further towards the
base of the twig, and here girdles it a second time, now merely cut-
ting through the bark, thus deadening the part beyond the girdle
without causing it to fall. The effect of this complicated operation
is to provide a safe lodgment for the egg, and so to arrest the
growth of the twig that the egg shall not be crushed, the young
larva finding, when it hatches, living wood at once available for its
food.

While the distance between girdle marks may be an inch or
more, it averages about five eighths of an inch, and the egg-slits
are made on the middle third of the space between the girdles.
Where the beetles are superabundant, this operation may be per-
formed several times upon the same twig, by females unable to find
each her separate branch for the deposit of her eggs. ‘The result
must be a serious loss of eggs, or of young larve hatching from
them, since only one of the latter can continue and mature in a
single twig. Although as many as eight or ten girdles may be
found on a twig in June, never more than a single larva occurs in
each the following spring.

123

The Egg.—Our earliest date for the eggs is May 22 (1903),
and they have been found in twigs of the elm and the other trees in-
fested, at frequent intervals from that date to June 24. As the
girdling of twigs was at its height May 29, 1903, and has been no-
ticed as late as June 10, it is probable that oviposition may con-
tinue at least to the latter date.

The Larva.—tThe larve of the preceding year are found in the
stubs of twigs on the trees in spring, but, according to our obser-
vations, all have pupated and emerged, as a rule, before the young
of the following brood begin to hatch. Our earliest date for the
hatching of the larve is June 13, and the latest is about the 24th
of June. The average length at the latter date is about a sixth of
an inch, which is nearly a third the length of the full-grown larva.
July 21, 1905, thirteen young larve measured from 4 to 11.5 mm.
(.16 to .46 of an inch), with an average of 7 mm. (.28 of an inch),
varying, that is, from one third size to nearly full grown, and aver-
aging about half their final length. The burrows of several speci-
mens varied in length, at this time, from 1 inch to 2% inches.

According to the observations of Mr. Titus, the young larva,
upon first breaking the shell of the egg, begins immediately to gnaw
a channel downward just beneath the bark, and turns inwards
towards the center when it is about half way out of the shell. When
it has thus freed itself from the egg it apparently backs up into the
shell cavity and cuts a small circular hole in the bark as a vent for
its excrement, which, up to this time, has been left in the cavity
originally containing the egg. It then burrows down the center of
the twig, making additional holes to the surface from one to two
inches apart as it progresses.

In small twigs, almost the whole interior is thus eaten out
(Pl. VIIL., Fig. b.), leaving only the shriveled bark and a very thin
layer of wood; and occasionally this inner cavity reaches nearly to
the truncated tip of the twig, as if the borer had worked first in a
direction opposite to its usual course. From the progress of a larva
down its twig, it appeared that its average rate from June 23 to
August 31 was a little less than a fifth of an inch a day (4% mm.),
but water-sprouts nearly two feet long were seen in September hol-
lowed out to the base by a single larva. When a burrow passes the
point of origin of a lateral twig, the base of this is sometimes eaten
out and used as a place of deposit for the larval excrement. Some-
times twigs passed by the larva in its downward descent are suc-
cessively cut off from within, the insect eating a circular groove
through the wood, so weakening the twig that it presently breaks

124

off. In one instance, followed in the insectary from the 12th of
July, 1905, to the roth of the following June, a larva thus ampu-
tated eight lateral twigs.

The cavity made in the twig, although apparently a close fit for
the larva, is nevertheless large enough to permit it to turn upon it-
self and to move in either direction. Of twenty-three larve exam-
ined May 22, eleven were lying with heads towards the tip of the
twig and twelve towards the base. It frequently happens, where a
tree is as heavily infested as were many of those in Decatur, that
eges will be laid in several small spurs all leading to a larger twig in
which all the larvee which live must finally meet. A destructive
competition must follow, since each infested twig harbors, finally,
only a single surviving borer.

When a larva passes down a smaller twig to a larger branch: it
burrows only in the newer wood immediately beneath the bark. In
such a branch it commonly takes a winding course, its track in one_
instance even doubling back upon itself for a considerable distance.

The larve, in various stages of growth, hibernate in their bur-
rows and finish their growth the following spring. May 22, for
example, they were found by Mr. Webster in the wood of the pre-
ceding year, still burrowing downwards, with the effect to kill the
lateral shoots as they passed.

Pupation occurs within the burrow, in a cavity shut off in both
directions by a firm plug of mingled woody fiber and excrement.
The beetle makes its way out of this cavity by pushing out the plug
at the end of the twig, and never, according to our numerous in-
sectary observations, by cutting through the wall of its cell.

As an example of the observations from which these biological
data are derived, the following abstract from the insectary notes of
one of the 1905 experiments may be given. ‘They were written
alternately by R. M. Webster and J. J. Davis, entomological stu-
dents in the University of Illinois, serving as insectary assistants at
the time.

On the 22d of July twigs of the elm containing Oberea larve
sent by Mr. Taylor from Decatur, were transferred to living elms
at the insectary, either by carefully grafting the infested twigs into
those of a growing tree or by hollowing out in the living twigs
artificial cavities in which Oberea larve were separately placed. By
the 25th of July evidence of the activity of these transferred larvee
was seen in the wood dust on the infested twigs; and by the tst of
August one of the larvee had passed the graft from its original twig
into the living stub on the tree, and had made a hole for the wood
dust an inch beyond this point.

125

August 8 one of the larve had cut off a lateral twig by burrow-
ing into its base for about 2 mm. and then gnawing a circular
groove from within. At this time four of the experimental larvee
were alive. On August II a second twig two and a half inches
from the graft was similarly cut off by the larva within, and on the
14th still another on the opposite side of the branch, and on the
16th a fourth. The dust holes made by these larve were from two
to three inches apart. On the 24th of August the fifth lateral twig
was girdled five inches down the branch from the graft. On the
29th and 30th, the sixth and seventh twigs were cut off, these two
being nearly an inch and a half apart. A larva which was forced
by grafting to work downward through a twig an eighth of an inch
in diameter, entered at its base a branch two fifths of an inch thick,
and continued its excavations just beneath the bark.

By the 5th of September only two of the larve remained alive,
and by the 20th one of them had burrowed a distance of ten and a
half inches, since its start July 12,—an average of .15 of an inch a
day. On the 25th of September it was noticed that this larva had
shortened its burrowed twig by cutting it off from within at the
place where its last dust vent had been made, and on the 2d of
October the open end of the burrow was found plugged with wood
dust, doubtless in preparation for hibernation. On the 14th of May
one of these twigs was opened and the Oberea pupa was found with-
in at the upper end of the burrow. ‘Transferred to a breeding-cage,
the beetle emerged May 18. ‘The other specimen, still a living larva
March 13, was used in an experiment with a carnivorous larva of
Cymatodera balteata, one of the enemies of this insect to be de-
scribed under another head.

The Pupa.—Our earliest date for the appearance of the pupa 1s
April 16 (1903) and the latest for its occurrence is May 22. On
the other hand, the earliest date at which we have seen the beetle
emerge is the roth of May, giving us thus, by inference, a period
of about three weeks in the pupa state, an estimate borne out by in-
dividual records from my insectary notes. From a pupa formed
April 17, for example, the beetle appeared on the 12th of May—a
period of 25 days; in another instance a pupa formed April 16
yielded the beetle the 13th of May—27 days; and in four others the
pupal period varied from 20 to 29 days. In one case of seemingly
delayed pupation this period extended only from May 3 to May 109.
_ The average of all our recorded observations is 23% days.

The dates of the pupal period are especially important, since one
of the readiest methods of controlling this pest is to clip off, by

126

means of pruning-shears, the infested twigs at the time when they
contain the pupze. In 1905 the greater part of the larve had pu-
pated by the 3d of May, at which time, among 19 specimens, 18
were pupz and only 1 was a living larva. An observation made on
the 5th of May showed this to be about the height of the pupal sea-
son, since all specimens seen were pupz except one. May 22, on
the other hand, of 20 specimens, 18 were adults, I was a pupa, and
1 a larva not yet transformed. ‘The last was probably parasitized.
From observations of 1905 directed especially to that point, Mr.
‘Taylor concludes that pupation begins, as a rule, with the begin-
ning of the ripening of the seeds of the elm, and that the pupa is
almost always to be found within two inches of the tip of the in-
fested twig. In the only exception noticed it was about 234 inches
from the end. It is normally formed with its head towards the tip
of the twig. In the only case seen to the contrary, the beetle form-
ing within the pupal chamber had perished without coming out.

The Beetle.—Our earliest date for the recently formed beetle is
May 10, at which date one appeared in a breeding-cage and three
were taken on trees at Decatur. As pupze were found until May 22,
the period of transformation is apparently about two weeks. The
sexes were seen pairing at various dates between May 21 and June
7. Adults began to die on the 29th of May, and the latest were
seen alive June 11. The entire life of the insect in the beetle stage
is consequently about a month.

The beetles feed on the veins of the leaves, gnawing these away
from the under side, thus sometimes making longitudinal slits
through the thickness of the leaf (Pl. VIII, Fig. e). This injury
at Decatur was easily seen from the ground on looking upward
through badly infested trees. In breeding-cages, where the food
was comparatively scarce, the leaves were thus riddled and killed,
the petioles were eaten, and even the soft tip of the twig was
gnawed into or eaten away.

Although not readily provoked to take wing, the adults are of
active habit, and have a good power of flight. Their slow dispersal
is not due to any lack of locomotive power, but to what, in view of
the destructive consequences to the species, we must look upon as
an aberration of instinct. ‘Though no trace of the beetles was found
in some parts of Decatur where elms were abundant, they were so
numerous in other parts of the town that a large percentage of their
larvee could not mature in the infested trees. Several females were
girdling the same twig and depositing their eggs there successively
although there was an abundance of fresh material a little distance

7

away. Twigs were found by Webster in which eggs had been laid
as many as eight separate times, with the usual number of girdlings
in each case, with the necessary consequence that only one of the
larve hatching could survive. “Late in May,” he says, “I began to
find sections of amputated twigs on the ground underneath the
trees, which showed plainly that this amputation was not the result
of a first visit of a female intent on oviposition. Ordinarily, the
tip of the twig is severed far enough back to include from two to
four or five leaves, and this amputated portion is free from egg or
larva. But I now began to find, scattered under the infested trees,
pieces of twigs which had been cut off at both ends, and those freshly
dropped contained in most cases either an egg or a newly hatched
larva, while in the older, withered ones there was more often a very
young larva, dead. As the season of oviposition advanced, these
secondary amputations, repeated perhaps five or six times on the
same twig, became more numerous, and an examination of the trees
disclosed the fact that nearly every twig contained at least one egg
or larva, and that some of them contained several. For those fe-
males that had yet to oviposit, there were no twigs not preoccupied,
and fully five per cent. of the amputated pieces on the ground con-
tained a larva or an egg. It became clear that the mortality result-
ing from this repeated oviposition and amputation was greater than
that from all other causes combined.”’*

Another seeming error of instinct is the senseless hostility which
these beetles exhibit towards each other, if one may judge by their
conduct in confinement. “If a male and female were confined at
all closely,” says Webster, “they would instantly attack each other
with such ferocity that within a few moments they would be roll-
ing helplessly about among fragments of legs and antennz, only the
basal portions of these remaining attached to their bodies. It was
found wholly impossible to transport living individuals without giv-
ing them ample quarters, and I was finally forced to give each a box
or vial to itself.’ +

DISTRIBUTION.

Although the first and much the most serious infestation was
found at Decatur, in Macon county, elms at Henry, Princeton,
Aurora, and Rock Island were found by Mr. Webster containing
Oberea larve in August, 1903. It was not certain, however, that
these belonged to our species, since Oberea tripunctata likewise in-

*Bull. Ill. State Lab. Nat. Hist., Vol. VII., Art. I., pp. 10 and 11.
tIbid., p. 10.

128

fests the elm. The same may be said of a trifling injury to white
elms noticed in Urbana in June, 1905, where tufts of leaves borne
on the tips of twigs neatly cut off after the manner of the elm twig-
girdler were occasionally picked up from the grass. Some of the
leaves were also eaten along the veins after the manner of these
beetles.

There can be no doubt, however, that our species is responsible
for a serious injury to white elms detected at Moweaqua, in Shelby
county, Ill., in May, 1905, by Mr. W. N. Dawson, a commercial
traveler of Decatur. Noticing accounts of the Decatur observa-
tions in the local press, he wrote to the office that he had discovered
the work of the elm twig-girdler upon trees surrounding the Illi-
nois Central station at Moweaqua, inclosing with his letter some of
the girdled twigs. When Mr. Taylor visited this place, May 25,
adults of Oberea ulmicola were still within their pupal cells, from
which they were preparing to escape by pushing out the plug at the
end. From under a single elm-tree about sixty feet in height, near
the railway station, one hundred and sixteen girdled twigs were
picked up, and nine other elms, all very large, were found infested.
It is very probable, in fact, that this species is generally distributed,
and that its discovery at Decatur was due to its extraordinary and
abnormal abundance there.

NATURAL CHECKS ON MUL/TIPLICATION.

Two insect species were found at Decatur preying on the elm
twig-girdler, one a minute hymenopterous parasite, Euderus lividus,
and the other a predaceous grub of a beetle, Cymatodera balteata.
The larvee of both these insects devour the Oberea larva in its bur-
row. Of seventy-two Oberea larve contained in elm.twigs from
Decatur and examined July 22, fifteen had been destroyed by the
hymenopterous parasite, which was present in the burrow as a pupa
in twelve cases and as a full-grown larva in three. The predaceous
larva of the beetle was repeatedly found in burrowed elm twigs
along with dead or mutilated larve of Oberea, and living Oberea
larvee exposed to its attack in the insectary were promptly devoured
by it.

: Euderus lividus Ashmead.

On splitting twigs burrowed by Oberea, Mr. Taylor frequently
found, in late June or in July, the young larva dead or wanting,
and in its place a small white larva, or a dusky pupa 2—3 mm. long
according to sex, the females being the larger. These pupz yielded,

129

in breeding-cages, the adults of a chalcid,—Euderus lividus, as de-
termined for us by Mr. Ashmead. A pupa obtained July 22 gave
the adult July 28, and a larva found on the first date had recently
pupated August 1, and had changed to the adult by August 7. The
species is recorded by Dr. Nason from northern Illinois, and by
Mr. Ashmead from Florida.

Description of Adult——Length about 2-3 mm. Rather slender,
abdomen slender, conically produced in female. Color dark metallic
blue, dorsum of thorax greenish, antennz black, 10-jointed, white-
hairy; tarsi white except last joint, which is dark brownish.
Thorax finely reticulate, with a network of raised lines; marginal
vein long, submarginal and postmarginal rather short, stigmal
short, the knob short-petiolate.

Description of Pupa.—Length of male, about 2 mm., of female,
2.5-3mm.; width,.6—8mm. Color light fuscous brown, dark-
ening as adults mature. Abdomen of male with last three segments
rapidly tapering to a blunt point, these segments often slightly
darker than those preceding, and but slightly longer; abdomen of
female with last three segments acuminately tapering, the sixth
slightly longer than the fifth, seventh half as long again as the
sixth, eighth narrow, twice as long as sixth. Ovipositor extended
forwards on the median ventral line to base of sixth segment. Pos-
terior legs nearly or quite attaining base of sixth segment.

Cymatodcra balteata Leconte.

The predaceous larva of this beetle is about a fourth of an inch
long, plump, elongate-oblong, with a projecting, strongly flattened
head. The body is somewhat hairy, flattened and whitish beneath,
dusky pink above changing to black in alcohol. ‘The back is marked
with a conspicuous confluent row on each side, next the margin, of
large round whitish spots, each with a dark center connected with
the dusky color of the back; and along the side is a dusky line just
above the ventral surface. The last segment is chitinous, and bears
at its tip a pair of slightly divergent strong recurved hooks.

These larve are very active, and are capable of burrowing into
the infested twig in search of their prey. A larva taken May 3 and
kept without food pupated between May 29 and June 19, and was
an adult in the burrow June 26. Another taken the 5th of May and
supplied with food after the 9th, continued in the larval stage over
the following winter. March 13 it burrowed into an infested elm
twig, entering at the plugged end, and devoured the Oberea larva

130

within, and May 8 it was still unchanged in the Oberea burrow. By
June 11, however, it had transformed to the adult, and made its
exit from the twig on the roth of that month. The adult has been
captured by us repeatedly in Illinois from late July into September.
The species is listed from New Jersey, and is said by Horn to oc-
cur from the Middle States westward to Kansas and Texas.
Description of Larva.—Moderately elongate with nearly paral-
lel sides, but tapering rapidly at each end. The length of the larg-
est specimen, 8 mm.; its breadth, 2 mm. Pale yellowish, marked
with dusky pink becoming purplish in alcohol, and tinged more or
less with chestnut at the ends. Skin soft, smooth, sparsely covered
above and below with pale hairs. ‘The head about as long as its
breadth at the antenne, black, varied with dark chestnut above and
below. The antennz, labrum, and inferior mouth-parts pale; the
mandibles black, broad, acute, a tooth or tubercle on the inner edge
near the base; the anterior edge of the labrum broadly concave.
Ocelli, three, equal, distance between them about half their diame-
ters. Hairs of the head arising from pale dots. Prothorax with
large black semicircular dorsal shield, narrow pale margins, and
a pale median line which broadens and opens out widely behind.
Suture between it and the head variable, blackish. The two re-
maining thoracic segments with black lateral margins and a U-
shaped discal patch; also a dark W-shaped mark in front of this;
some oblique lines on the mesothorax, and an irregular posterior
border of black on the metathorax. Thoracic legs rather short and
stout, dark dorsally, the femur with a pale annulus near the middle;
coxal sutures ferruginous or blackish. Abdomen g-jointed, the
segments, except the last, about four to six times broader than long,
gradually lengthening from before backwards. ‘The lateral mar-
gins, except those of the last segment, dark. A broad median dark
dorsal stripe about as wide as the head, and slightly more than half
as wide as the body, ending on the base of the last segment, inter-
rupted at the sutures and sometimes divided by a pale median line.
Between this stripe and the lateral margin, a subdorsal stripe or con-
fluent line of pale rounded spots, one for each segment, each with
a black central patch connected at the posterior margin of the seg-
ment with the dorsal stripe; beneath yellowish except for a few
purplish dots variably evident on the hind margins of the posterior
segments. Last segment greenish beneath, with a prominent anal
tubercle and a chitinous fork at the tip. Dorsal surface with a
round black patch on the apical two thirds. The anal fork is dark
chestnut or black, the outer sides of its prongs about parallel, but

131

divided within by a notch intermediate in form between a V and
a U. Apical part of each prong acute, curved ventrally upward
and a trifle forward at tip.

Described from three examples in alcohol.

PROTECTIVE MEASURES.

The fact that the elm twig-girdler is deficient in the instinct of
dispersal, and hence remains to breed in the twigs of the tree in
which it originated, makes it a dangerous insect, but at the same
time exposes it to wholesale destruction by artificial measures easily
applied to the small number of trees which it is likely to infest to a
dangerous degree. Its feeding habits and its life history suggest
two practicable methods of destroying it. Since the beetle feeds on
the leaves of the elm, it may be poisoned by arsenical insecticides
sprayed on the leaves during the last week in May; or, since it
completes its transformations in its burrow, it may be killed in the
larval or pupal stage by trimming off and burning the infested twigs
in spring at any time preceding the middle of May. A combina-
tion of these operations, first cutting off the visibly infested twigs
and then spraying the tree to destroy any beetles coming in from
outside or emerging from twigs overlooked, would be a doubly ef-
fective safeguard against further injury. Both these methods were
tested at Decatur with encouraging results.

Infested twigs are easily recognized in spring by their stubbed
ends, left by the breaking off of the twig at the place where the
outer girdle has been made by the female before depositing het
eges. ‘I'wigs containing the insects are commonly a fourth of an
inch or less in diameter, and the pupa is formed almost invariably
within two inches of the end of the stub. By a practical test of the
trimming method, made in Decatur May 5, it was found that badly
injured trees were easily cleared of infested twigs, which were
readily seen among the scanty foliage, but that it was more difficult
to make sure of a thorough operation where the injury was less and
the foliage more abundant. Eighteen trees ten to thirty feet high
were pruned by Mr. Taylor, with one assistant, in an average time
of half an hour to the tree, using-a 14-foot step-ladder, a pruning-
saw, and a pair of pruning-shears with handles eight and twelve
feet long. No way was found, however, to clear by this means
trees more than thirty feet in height, and for these the spraying
method must be the main dependence.

In Mr. Taylor’s report of an extensive spraying experiment
made at Decatur May 23, fifteen trees averaging about twenty-one

132

feet in height, and treated with arsenate of lead, are comparable
with twelve trees, all less than thirty feet high, left untreated as a
check. The treated trees were sprayed twice, once May 23 and
again June 6. Ten were sprayed with the arsenate of lead of the
strength usual in orchard practice—12™% ounces of sugar of lead
and 5 ounces of arsenate of soda, dissolved in 50 gallons of water.
Five of the trees were sprayed with a solution of twice this strength,
the solid ingredients being dissolved in 25 gallons of water. All
twigs which fell from these various lots, both checks and experi-
mental trees, were gathered and counted daily, with the general re-
sult that the check trees dropped in all 1148 twigs, or an average of
96 per tree; those treated with the weaker spray dropped 420 twigs,
an average of 43 per tree; and those treated with the stronger spray
dropped 65 twigs,—an average of 13 per tree. In other words, the
weaker spray preserved 55 per cent. of the twigs which would
otherwise have fallen, and the stronger spray, 85 per cent.

Only one of the largest trees was sprayed under conditions to
serve the purposes of an experiment. This tree was about seventy-
five feet high, and from it fell only 95 twigs in all, while eight un-
treated trees, averaging sixty-four feet in height, gave a total of
12,721 fallen twigs, an average of 1490 per tree. The number
varied under the different trees from 937 to 2029. ‘The ratio of
benefit on this large tree thus seems to have been 94 per cent. Ex-
cept for the difficulty and labor of spraying large shade trees, this
insecticide treatment was as satisfactory as could be expected of any
like operation.

When the insecticide was first applied there was but little wind,
and the weather was fair. A heavy rain with wind followed the
second spraying, and doubtless diminished somewhat its effect.
Twigs fell in considerable numbers until the 28th of June, after
which but few were collected.

In preparing the arsenate of lead, the sugar of lead and the
arsenate of soda are separately dissolved, and poured, in succes-
sion, into a quantity of water sufficient to reduce the solutions to
the strength desired. In the Decatur experiment a Morrill and
Morley “Eclipse” hand-pump No. 6 was used, with two 35-foot
lengths of hose and 12-foot extension poles. A 14-foot step-ladder
was sufficient to give access to the tops of trees of medium size,
while for those from sixty to eighty feet high, 65-foot extension
ladders were used—the property of the Decatur Fire Department.
The amount of the insecticide required, varied from five to ten gal-
lons for the small and medium trees to forty gallons for the largest

PLATE VY it

Tue Evo Twic-crrpier, Oberea ulmicola: a—adult beetle, length nearly '2 inch;
b—egg enlarged, and others in position under bark of twigs; c- larva, d—pupa,

both enlarged; e—elm leaves, showing leaf veins eaten out by beetle in feeding.

133

elm treated, and the time required for the spraying varied simi-
larly from about ten minutes to an hour. ‘The force necessary was
three men and a boy, the latter to keep the solution constantly
stirred during the spraying. ;

The most suitable time for the first spraying is obviously that
just preceding the appearance of the adult beetles on the leaves.
May 23, when this experiment was begun, 5 per cent. of the insects
in the twigs were still larvae, another 5 per cent. were pupz, and
go per cent. were adults about to emerge. It was estimated by Mr.
Taylor that possibly 5 or to per cent. of the beeties had already
come out of their burrows and were feeding on the leaves, although
very few, if any, twigs had fallen as yet in consequence of the gird-
ling operations of the female beetles.

DESCRIPTION.
(Plate VIII.)

Adult—Form slender. Head, antennz, and elytra black, with
gray pubescence, becoming long and dense on the head, nearly ob-
scuring the punctures, and darker plumbeous-gray on the thorax.
Antenne slender, long, five sixths of the length of the entire insect.
Head somewhat feebly and sparsely punctate, with strongly defined
median line, especially in the posterior portion. Thorax yellow, cal-
losities black, occasionally with a smaller black antescutellar spot on
each side; just above the leg there is usually another variable black
spot, either smaller or much larger than the others. Elytra with basal
portion on each side of and including the scutellum, yellow, occa-
sionally with a longitudinal yellow streak on each elytron, extending
from the base nearly to the apex, which is emarginate and sub-bi-
dentate; the surface comparatively sparsely and feebly punctate.
Epipleure yellow. Ventral surface usually yellow, but occasionally
with a portion of the thorax and of the second and third abdominal
segments and less frequently the first and last segments black. Pune-
tuation very shallow, nearly obsolete on abdominal segments. Prox-
imal portion of legs yellow, distal portion black.

Length, 9-13 mm.; width, 1.2-2.0 mm. Average length,
12 mm.; width, 1.9 mm.

Egg.—tLength, 3 mm.; width, 0.6 mm.; slightly reniform, of
a creamy white color, without perceivable reticulations.

Larva.—Length, 14 mm. Head much smaller than thoracic
segments, body decreasing in width posteriorly with moderate uni-
formity to the eighth segment, which is considerably smaller, the
anal still more reduced; body light straw-color, the two posterior

134

segments lighter; head anteriorly dark brown, posteriorly the color —
of the body, mandibles darker than anterior portion of head. Cer-
vical shield brownish yellow, anterior surface smooth polished,
terminating posteriorly in a slightly raised transverse ridge. The
apical declivity is shagreened, more finely posteriorly and centrally ;
narrow median dorsal area whiter ; the lateral oblique, sinuate grooves
darker. In front of the shagreened area are a few short erect hairs,
with larger ones placed laterally on this segment. On the next seg-
ment there are but two lateral hairs on each side, and none on other
segments until the eleventh, which has a single stout bristle on each
side considerably above the margin, and a transverse row of hairs
along the posterior margin. The anal segment has a considerable
number of long curved hairs along the lateral and posterior areas.
The lateral margins of each of the abdominal segments, just below
the spiracles, have an inflated appearance, and segments three to
ten inclusive are strongly sculptured, especially on the dorsal sur-
face, by transverse, tubercular, flattened ridges which are minutely
shagreened. ‘The sculpture of these is clearly shown in Plate VIII.,
Fig. c. The lateral inflations, with deep intervening constrictions,
give the larva when extended a somewhat moniliform aspect.

Pupa.—Length, 13 mm.; color uniformly light yellow; head
with nearly triangular impressed area between the bases of the
antennz, on each side of which are a: pair oi closely set hairs.
There are two clusters of minute spinules on the clypeus. ‘The an-
tennz, being abruptly bent downward, give the head a decidedly
square appearance. They extend backward to just beyond the mid-
dle femora, where they turn forward along and outside of the an-
terior and middle legs, the posterior pair of legs being folded undet
the wings. ‘There is a minute, robust, hooked spine on the marginal
ridge of each of the abdominal segments except the terminal, the
hooks being reversed; there is also on each of these segments a
transverse dorsal elevation armed with irregularly placed minute
stout spines. The terminal segment is provided with a number ot
long hairs.

ON THE LIFE HISTORY, HABITS, AND ECONOMIC RE-
LATIONS OF THE WHITE-GRUBS AND MAY-
BEETLES (LACHNOSTERN A).

The insects generally known as white-grubs are the young, or
larve, of the large brown beetles commonly called “‘June-bugs” or
May-beetles. For a practical knowledge of these destructive insects
it is necessary that we should know the various species of them
which do serious injury to agricultural and to horticultural crops;
the life histories of all these species; their relative numbers in dif-
ferent parts of the state in different years and in different periods
of years; their food, both as grubs and as adult beetles, including
their common preferences where several kinds of food are available
to them; their significant habits, especially those of reproduction;
their relations to variety of weather and to seasonal change; their
modes, times, and places of hibernation; the range of their daily
movements and of their movements of migration and dispersal;
their enemies, their diseases—especially those of a contagious char-
acter, and the other natural checks on their multiplication; their
relation to varieties of soil, to its physical condition, its moisture,
and its exposure to the sun; their relation to varieties of the subsoil
also; the effects on their continuance and increase, of various agri-
cultural operations and kinds of farm management; and their own
effects, under varying conditions, on the several kinds of crops sub-
ject to injury by them. Finally, the whole field of preventive and
remedial measures of a more or less artificial character must be
thoroughly explored, including the results of practical experiments
on the scale of actual farm management.

The subject is made especially difficult and complicated by sev-
eral facts and circumstances. There are many species of these
insects recognizable in the beetle stage but seemingly not distinguish-
able as larve; hence one frequently can not tell what kind of grub
he is dealing with until he has reared specimens to the adult. The
life history of these insects has a prolonged cycle, probably of three
years, but just how many is not definitely known, and life histories
can be completed only by keeping specimens alive, under more or
less artificial conditions, for this entire time. ‘The various species
differ sufficiently in certain parts of their life histories to make it
necessary to follow each out separately; and it is not impossible
that important differences may be found due to differences in lati-

136

tude and climate, between northern and southern Illinois; hence
each species must be studied in different parts of the state. The
most important species—that is the most abundant ones—are not
the same in all parts of Illinois, and the relative importance of the
various species must be made out for each region separately. The
unexplained sudden disappearance, several times noticed by us, of
nearly the whole grub population of badly infested fields before
their transformation to the pupa, suggests the occurrence among
these insects of contagious diseases—a supposition borne out by sev-
eral field and insectary observations; and the whole subject of their
bacterial and other fungus parasites consequently invites attention.
The enormous effect of the rapid multiplication, under favorable
conditions, of certain insect parasites—a hymenopterous enemy,
Tiphia inornata, especially—requires a critical and complete study
of the life history of these parasitic insects also, especially as there
is some probability that we shall be able to increase their efficiency
by artificial measures.

No one has heretofore undertaken to work out to a finish this
difficult but highly important economic problem, and our present
knowledge of the white-grubs is a patchwork of fragments, contrib-
uted by a considerable number of observers working on various
species and in different parts of the country. The nearest approach
thus far made to a continuous investigation of the subject was car-
ried on in this office in the years of 1886—18g90, and its results were
published in 1891 in Volume III. of “Insect Life.”*

They were also incorporated, with some later studies, in the
Eighteenth Report of the Illinois State Entomologist, printed in
1894. In the year 1906 I finally began what I now hope may prove
to be a steady and comprehensive study of this problem for the
state of Illinois; and I have now to report some of the first results
of this work, which I have incorporated, however, with other data
and conclusions in a way to give us a fairly full synopsis of the
present state of our knowledge, and a clear view, consequently, of
its deficiencies.

THE ECONOMIC SPECIES.

The kinds of white-grubs common enough in Illinois to attract
attention because of their injuries, belong, so far as we now know, to
nine species, although it is likely that this list would be longer if the
injurious grubs of southern Illinois were as well known to us as
those of the central part of the state. Besides these nine injurious

*“On the Life History of the White-grubs.” By S.A. Forbes. Insect Life, Vol. III., No.
5, pp. 239-245.

137

grubs, there are three other very abundant kinds which resemble
closely the injurious species, although they are themselves harmless
in the grub stage.

Eight of the species known to be injurious belong to the genus
Lachnosterna and one to the genus Cyclocephala. Of the abundant
but harmless grubs, one, frequently called the muck-worm because it
lives in stable manure, is known to science as Ligyrus relictus; an-
other, called the carrot-beetle in the adult stage, is L. gibbosa; and
the third is the larva of the green June-bug of southern Illinois and
of the Southern States generally, known in the beetle stage as Allo-
rhina nitida. All the last three species are injurious as beetles, but
only one of them, the larva of the carrot-beetle, is at all injurious as
a grub, and then only slightly or occasionally so. The eight species
of Lachnosterna known to be injurious in Illinois are L. fusca,
rugosa, inversa, implicita, gibbosa, tristis, ilicis, and hirticula; and
the injurious Cyclocephala is C. immaculata.

Life Histories of the Injurious Species —The life histories of
the white-grubs of the genus Lachnosterna are very imperfectly
known, especially as to the length of time required for the growth
and development of a complete generation. ‘The literature of the
subject records, in fact, but a single case in which a Lachnosterna
has been reared frdm the egg to the adult. An egg of L. arcuata
laid in Washington about June 8, 1893, hatched in approximately
eleven days, and changed to the pupa August 8, 1895, and to the
beetle twenty-three days later.* As this beetle would doubtless have
hibernated in the earth to emerge the following spring and lay its
eges in June, the entire period from the egg to the egg again was
three years. This is the length of the life cycle which has com-
monly been inferred, from circumstantial evidence, for our species
of Lachnosterna generally. It is worthy of note, however, that Melo-
lontha vulgaris, the European white-grub nearest in classification
and habits to our American species, has been found, according to
Xavier Raspail, to have, in France, a period of three or four years
—the shorter period if the years are moist and the longer one if
they are dry.t In Germany, on the other hand, this species has a
four-year period at the north and a three-year period at the south,
with various occasional exceptions and irregularities of appearance;
and a related species, M. hippocastani, has a five-year period in north
Germany. Our American species of Lachnosterna will probably be
found to present similar variations of life history.

*“Biologic Notes on the May-beetle Lachnosterna arcuata Sm.” By F. H. Chittenden.

Bull. 19, N.S., Div. Ent., U. S. Dept. Agr., p. 77.

= Ale de la Soc. Zool. de France, 1891, p. 271; Mém. de la Soc. Zool. de France, 1893, T. VI.,
p- 202. ‘.

138

Whatever the length of life in the grub stage, all our most
abundant species of Lachnosterna begin to pupate in June or July
in central Illinois, and begin to change to the beetle in August or
September, remaining, with rare or doubtful individual exceptions,
under ground in this stage until the following March, April, or
May. ‘They then emerge from their winter quarters, feed on the
leaves of various trees, and pair and lay their eggs in the earth in
June and July. An exception should perhaps be made, provisionally,
of L. tristis, concerning which my records are unusually imperfect,
agreeing, so far as they go, with those of the other species of our
list, but stopping short before the middle of June. That is, we have
an abundance of the beetles collected from the latter part of March
through April and May and into early June, most frequently, how-
ever, in May, but have no collections in any stage at any date later
than June 5. Four of our lots of tristis, collected in March and
April, were beetles taken from the earth, which must have trans-
formed the preceding summer or fall.

Pupz of the above species have been taken by us from their
underground cells only in June, July, August, and September, and
the adult beetles have been found under ground in the cells where
they originated, in August, September, October, and November, and
again in April and early May. Adults of various species have been
seen pairing in May, and in one case in June, and eggs of seven of
these species—tristis being omitted—have been secured in June and
July, much the greater part of them in the former month. So far
as my rather scanty records go, the eggs may be expected to hatch
from ten days to four weeks from the time of deposit. My dates
for the hatching of eggs of known species are, for inversa, June 23
and July 11; for fusca, June 27; for implicita, July 16, 21, and 24,
and August 7; and for hirticula, July 7.

From this it will appear that white-grubs found in the earth
beyond the middle of September will not change to the beetle that
year, but, barring destruction by parasites and other fatal accidents,
may be’ expected to pass the winter as grubs and to continue in
that stage at least until the following June. This is a point of
special economic interest, since the owner of infested fields needs to
know whether the grubs in the ground during the latter part of the
season will continue there in dangerous numbers during the follow-
ing spring, or whether he may expect relief from their injuries by
reason of their change to the beetle.

The data of my collections, when taken in the aggregate for
several years, give little indication of any fixed order of succession

139

in the first appearance of the different species of Lachnosterna in
spring. IJnversa, fusca, rugosa, hirticula, and tristis have all been
taken by us in the later days of March, and gibbosa on April 6.
Implicita and ilicis have made their first appearances about a month
later than the average, but, although implicita is sometimes excess-
ively abundant, these two species have been much less frequently
taken by us than the others, and the record might have been differ-
ent if the collections made had-been equally numerous. The dates
of last occurrence are also nearly the same for these species, and
their periods of greatest abundance do not vary greatly.

Fusca, however, commonly appears in large numbers at electric
lights about a week earlier than the other species, and gibbosa is
about as much later than the others—a fortnight later than fusca.
Our records of egg-laying are substantially the same for all the
seven species covered by them. So far, consequently, as the mere
period of adult activity is concerned, these insects are virtually one
species, and we must look to other facts and conditions for any spe-
cific distinctions of habit or agricultural relation.

I find that the data of the relative abundance and dates of emer-
gence of the various species derived from electric-light collections
disagree widely with the data of collections made from the food
plants of the beetles at the same time. Apparently some of the
species are more strongly attracted to lights than others. In 1891,
and again in 1906, collections were made at Urbana from trees and
from lights during the greater part of the active period of the May-
beetles, with the results shown in the following table.

LACHNOSTERNA AT [LIGHTS AND ON TREES, IN COMPARISON. URBANA.

1891 1906
Lights Trees Lights Trees
GME SP CCUMEMS: = . stearic wlewsiale es cdisdes s 1874 836 142 3484
HEPA OSAariccjsg asst oe screlels ddiaie cates se .02 .02 .00 .03
RENESAS Hi sylstoe Gove os cys, s Gun eee dl aiw'w's. 00's .76 RE! 54 00
HEPPGLD EN clea Ns cclelena iota cracele’e.e ieveisee sera eneye, eyes “00 00 .02 .00
NPIS Cal is <8 a Re pects cle sa aia oes os 05.0% .05 123 00 01
NEMA OS leeches 3 aisierd whois eveiels siajeels sas shs 00 00 24 .06
Wee PUGItAL os Sonat wiatese 00 00 15 SP
BRIE WETICEIA Ja oo slic vcs Wiese vous sess .10 42 .03 .07
Lich: es ee - 100 00 .02 io)
ly TEPISETIS AS SR ORIG EOE CIO aieaccne .07 00 00 01

140

In 1891, when 1,874 specimens were taken from lights and 836
from trees, the dominant species at lights was inversa (76 per cent.),
hirticula, tristis, and fusca following with ratios of 10 per cent., 7
per cent., and 5 per cent. respectively. ‘The dominant species from
trees, on the other hand, were hirticula (42 per cent.), imversa (32
per cent.), and fusca (23 per cent.), the only other species being
gibbosa (2 per cent.). The results for 1906, when 142 specimens
were taken at lights and 3,484 at trees, were equally discordant.
The leading species at lights this year was inversa (54 per cent.),
rugosa and inplicita following with 24 per cent. and 15 per cent.
respectively; while the leading species in trees was implicita (72
per cent.), followed by tlicis and rugosa, 10 per cent. and 6 per cent.
respectively.

Variation of Numbers in Different Localities and Years——The
numbers of the several species vary greatly from year to year in the
same locality, and in different localities during the same season. It
consequently happens that the dominant species in a locality may be
different in successive years, and that the dominant species in one
locality may be different from that in another, within the same year.
Collections have not been made on a large enough scale or in suf-
ficiently continuous series to enable us to exhibit these differences in
any detail, but the following may serve as illustrations :—

Collections made at a street-lamp in Maywood, near Chicago, by
O. S. Westcott,* on seventeen nights from May g to June 14, 1887,
contained 7098 specimens of fusca and 313 of gibbosa—fusca pre-
dominating in a ratio of more than 2% to 1; and collections made
the following year at the same place by the same person, on seven-
teen nights between June 2 and July 2, gave 73 specimens of fusca
and 1,836 of gibbosa—gibbosa now predominating in a ratio of ©
25 to 1. The difference in the collection period of the two years
was due to the difference in the weather of the spring, which was
backward and stormy in 1888. If we compare the collections of the
same periods for these two years—June 9 to 14 in 1887, and June 9
to 13 in 1888—we have 96 specimens of fusca to 82 of gibbosa in
1887, and 29 of fusca to 1,020 of gibbosa in 1888.

A similar comparison may be made between the contents of fre-
quent collections from trees made at Urbana through the whole
period of activity of the May-beetles in 1891 and again in 1906—836
specimens in the former year_and 3,484 in the latter. (See table
on p. 139.) In the collections of 1891 the dominant species were
hirticula (42 per cent.), inversa (32 per cent.), and fusca (23 per

*“Fntomologica Americana, Novy., 1888, Vol. IV., p. 155.

141

cent.), the only other species represented being gibbosa (2 per cent.).
In 1906, on the other hand, the dominant species was implicita (72
per cent.), the remaining species, mentioned in the order of their
abundance, being ilicis (10 per cent.), hirticula (7 per cent.), rugosa
(6 per cent.), gibbosa (3 per cent.), and fusca and tristis (each 1
per cent.). This latter comparison is vitiated, however, by the fact
that the collections were made from different kinds of trees, those of
1891 mainly from butternuts and hickories, and those of 1906 from
poplars, willows, elms, and oaks,—another example of the fragmen-
tary and disjointed character of the data now available for a study
of this subject.

It so happens that extensive collections of May-beetles were
made in 1888 both in Cook county, IIl., by Westcott, and in the Dis-
trict of Columbia by J. B. Smith,* and a comparison of the relative
numbers of the dominant species in these two widely separate locali-
ties would be possible by their means if it were not for the fact that
Westcott’s specimens were all taken at lights and Smith’s were ob-
tained from trees and shrubs. As already shown, collections are
not comparable when made in these different ways.

Much more nearly equivalent collections were made in 1906 by
two assistants of my.office, one working at Urbana, in Champaign
county, between May 26 and June 23, and the other at Elliott, in
Ford county, between May 23 and June 5, the first collecting at
lights scattered through fields of grass a total of 142 specimens in
ten nights, and the second obtaining at a single light in a large corn
field 389 specimens in six nights. At Urbana the dominant species
was inversa (54 per cent.) ; at Elliott it was gibbosa (71 per cent.).
At Urbana gibbosa was not taken in these light-collections, and at
Elliott inversa made but 20 per cent. of all obtained.

A further profitable comparison may be made of data contrib-
uted by Prof. M. V. Slingerland from the product of light-traps
kept in continuous operation at Ithaca, N. Y., during the seasons of
1889 and 1892. Four hundred and thirty-eight specimens of
Lachnosterna were taken during the first of these years, and 273
during the second. Fusca was much the most abundant species in
both years, making 76 per cent. of the product of the traps in 1880,
and go per cent. in 1892. Dubia was next to fusca in 1889 (15 per
cent.) ; and this species and ilicis, each 4 per cent., were likewise
next to fusca in 1892. The similarity of the records for these two
years is possibly due to a three-year period of the dominant species,

*“Proc, U. S. National Museum, 1888, Vol. II., p. 488.
fCanadian Entomologist; March, 1893, Vol. XXV., p. 81.

142

fusca, but, unfortunately, as no comparable collections were made
in the intermediate years, the evidence is not complete. Westcott’s
Maywood collections, already referred to, on the other hand, hint at
a two-year period for L. gibbosa. ‘This species predominated over
fusca in 1886, as shown by records made on five nights, from the
26th of May to the Ist of June, in a ratio of 3.6 to 1, and again in
1888, in a ratio, as already stated, of 25 to 1, but was much less
abundant than fusca in the intermediate year.

Foop AND FEEDING HABI't's OF THE SPECIES.

The white-grubs and the May-beetles, larve and adults of the
same insect species, differ totally in their food and feeding habits,
the grubs eating the roots of various kinds of plants and the beetles
eating the leaves of trees and shrubs. In the absence of any means
of distinguishing the species one from another in the grub stage, no
evidence has been obtained of any special choice, by any of. the
species in this stage, among the various elements of the food of
grubs in general. So far as known, all of them may take, with
equal relish, all kinds of food which any one of them will eat. If
the different species of grubs do indeed make definite and varied
choice of food, the fact may be ascertained by breeding to the adult,
for determination, pupz and full-grown grubs obtained in various
situations near or among different kinds of food plants; but there
is at present too little recorded information on this point to permit
us to infer any difference whatever in the choices of our more
abundant species.

The species of beetles themselves, on the other hand, differ con-
siderably, although not sharply and completely, as a rule, in their
choices of food where several kinds are equally accessible to them.
Evidence of these preferences has been obtained by us in three dif-
ferent ways: (1) by experimental feedings with beetles kept in
confinement; (2) by parallel collections of beetles made from dif-
ferent kinds of food plants; and (3) by the dissection of specimens
of various species, made to determine, by an examination of the
contents of their alimentary canals, what kind of vegetation they
have been feeding on. ‘The first method shows what the beetles may
eat under stress of hunger, or perhaps with starvation as a penalty
for refusing what is offered them; the second shows what the dif-
ferent species actually choose when a choice is open to them; and
the third enables us to determine with certainty what the beetles
have eaten where direct observation is impracticable. ‘The results
of our feeding experiments have been so different from those ob-

145

tained by making collections from the food plants at night that they
evidently have comparatively little real -value. For example, leaves
of Osage orange were offered, without other food, to fusca, inversa,
implicita, tlicis, rugosa, and tristis. ‘They were eaten moderately
by implicita and rugosa, and slightly by fusca, inversa, and ilicis,
but were constantly refused by ¢ristts. On the other hand, extensive
observations made in the field have given us no instance of actual
feeding on this plant in the open air by any of our species, although
it is everywhere in common use as a hedge plant.

The following table shows the different kinds of food offered to
Lachnosterna beetles in breeding-cages in 1904 and 1905, and data
as to the readiness with which each sort of leaf was eaten when
but one kind of food was placed in the cage.

RESULTS OF FEEDING EXPERIMENTS WITH
MAy-BEETLES (LLACHNOSTERNA).

: g | 8 | 5

Re tee eee | ee yee. hs Be re

cS) & 2 Ray | = a <
Carolina Poplar,

(Populus monilifera) .. 1 3 3 3 3 3 3 2 2.62

\ Vou oy AS Ainareg niger ~ 3 3 2, 3 _ 3 i. Pig AO
ROVA agenesis Joveus\ exares.exei'e a. - 2 3 2 2 - 3 3 2.50
MVS ene asco siie eh eva e eseis 3 2 3 2 2, 3 3) 3 2uO2
Je 0) Oe ECA 1 z 3 3 3 3 3 1 Deh
Ox-el der i. ar. st shes 1 2 3 1 3 2 2 0 WeKe
MESIMTAIIE S reseveleraie.aie\e ane 1 0 3} 0 3 3 BBS Me 50
HSA GIy ies cisra,ee ier etasee 1 0 1 0) 1 i 1 0 71
Mae PAIS Teac sie oe 1 D, if 1 3 2 al 0) UA Sy/
Tulip tree,

(Liriodendron) .. 0 1 il 0 1 1 0 0 2S
NTC AGE ais slave je ele os - 1 a 2 2 ~ Ms oe 1.40
NEMA Chlaiele fake cisco! eialerss - i 2 - 1 - - ses
(Cini) ce\ (AN Ge piomee co oics - 1 1 - 1 - - - 13
(COidta Cae oe Cerne - 2 2 2 2 ~ 1 0 1.50
(Gee Sameera : 2, 2 2 1 ~ 1 Ona larG)

1l=slightly eaten, 2 =moderately eaten, 3= freely eaten, 0 = refused to eat, - = not offered.

An attempt was also made to test the general food preferences
of each species by offering several different kinds of food in the cage
at once. Under these conditions, L. fusca, inversa, and implicita
ate most freely of Carolina poplar and willow; L. ilicis and hirticula
ate most freely of oak, but freely, also, of Carolina poplar and elm;
and L. tristis ate only oak when that was present. L. rugosa se-
lected poplar and elm, and L. gibbosa, oak and elm.

In 1906, at Urbana, extensive collections were made with equal
care from each of the four different kinds of trees which May-beetles

144

seemed to prefer as food. The beetles were gathered by shaking
them from the trees at night and picking up those which fell to
the ground.

The following table gives the results of these collections made
at Urbana from Carolina poplar (cottonwood), willow, oak, and
elm, on twenty-six different nights between May 14 and June 28,
1900.

COMPARATIVE COLLECTIONS OF LACHNOSTERNA FROM Foop
Prants. Ursana, 1906.

Species Poplar Willow | Oak Elm
: Pp Ae TS: Per | P

| N cant No can | No bade No. coor

| | }
L,. implicita........; | 1456] .58 | 855 | .34 35 “Ot. | HL .07
TS SEU ORAS ..eniy ote oo | 169] .85 31 15
PSP 1D DOSA eshte ee 73 | i TA IW EOL 18 mg, 4 .04
esa ee ctae ae 39; .85 | 6 13 31 .02
Pp Jebhe stele ene aan 10} .04 | 6 :03" |°209" | 786 17 .07
TW aAnVCESAsins dhs oes 5] ee: eee
DRUM CiS 81. oro sere 23) | a se 21 .07
EL opristins. Greece. | | 25 | 1.00

| ’

ROtALe eR. 2 aa ae 1754 | 879 | 607 244
Per cent. on each tree .50 | .25 eS [267

From the foregoing table it will be seen that poplar (cotton-
wood) was the favorite food, 50 per cent. of the specimens being
taken from this tree, and that willow follows next with 25 per cent.,
oak with 18 per cent., and elm with 7 per cent., poplar and willow
together yielding 75 per cent. of the insects. Apple leaves were
often eaten freely, but no trees were suitably situated for experimen-
tal field-collecting, and hence no comparative records were made
which included apple. Apple orchards in the southern part of the
state have been reported by assistants as sometimes almost stripped
of their leaves. This was notably so in Jackson county in 1904.
The pecan- and persimmon-trees of southern Illinois often suffer
severely by having their foliage eaten by the beetles.

Certain species of the beetles exhibited marked preferences in
the choice of food. L. hirticula, ilicis, and tristts had a special liking
for oak, the last named being taken from no other tree. L. implicita,
gibbosa, fusca, and rugosa were most abundant on poplar, rugosa
seeming to avoid oak and willow. Not enough specimens of L. in-
versa were taken to warrant conclusions concerning its preferences.

All of the May-beetles taken at lights in the open fields at night
in 1906 at Elliott, Ford county, and at Urbana, Champaign county,
were carefully dissected and the contents of the alimentary canals

145

were examined microscopically. Nearly 40 per cent. of all the
May-beetles taken had eaten nothing. ‘This percentage was much
the highest for specimens taken early in the season, 62 per cent., for
example, for those caught before June 6. Probably most of these
empty beetles had just come from the earth and had not yet begun
to feed. Nearly all of those captured in the fields at lights which
had taken food had eaten the leaves of trees, as was shown by the
presence in their intestines of small pieces of leaves exhibiting the
netted vein-structure and other characteristics of the foliage of the
common trees of the vicinity. Only six specimens of about six hun-
dred dissected, had eaten the leaves of young corn. Five of these
specimens belonged to L. rugosa and the sixth to L. inversa. Four
additional specimens of L. rugosa were taken at Urbana directly
from corn while feeding on it. As these ten beetles represent only
about 134 per cent. of the whole number examined, the facts indi-
cated by them are of little economic significance except as going to:
show that May-beetles, of these two species at least, emerging in
corn fields at a distance from trees too great to enable them to find
their more ordinary food, may nevertheless subsist on leaves of
corn. ‘The same facts have been shown with reference to blue-grass,.
and it seems probable that, in the absence of other food, beetles may
be able to live on the blue-grass of our pastures. With their actual
powers of flight and their strong disposition to assemble in trees at
night, not merely to feed but likewise to copulate, their ability to
feed on grass and corn seems to signify but little. Corn, oats, wheat,
clover, and grass fields were repeatedly examined in both Ford and
Champaign counties with a view to the detection of any injury
which might have been caused by these beetles. Occasionally at
Urbana, and more frequently at Elliott, corn plants were found
which, though uninjured in the evening, were partially eaten by the
next morning, and, as already mentioned, four May-beetles (L.
rugosa) were taken directly from the plants while feeding on them.
Dissection of these specimens showed beyond a doubt that they had
eaten the leaves of corn. Two hundred and sixty-two specimens of
this species were taken in 1906, 169 of them from poplar, 31 from
elm, and 62 from other situations, and only 9 of these had eaten
corn, as sown by dissection.

MovEMEN'TsS OF MIGRATION AND DISPERSAL.

As the larve known as white-grubs never appear above ground
except by accident, and as they are sluggish insects, incapable of
rapid locomotion under ground, each is practically confined, so far as

146

we now know, to the immediate neighborhood of its origin. The
grubs change location slowly as their food is exhausted, and injured
spots in an infested lawn or grain field will gradually enlarge in all
directions, the white-grubs moving outwards into fresh pasturage
as the infested vegetation dies from the destruction of its roots. The
grubs also sometimes gather in from all directions towards a par-
ticularly attractive patch of their food plants; but there is nothing
to show that they move from place to place by definite underground
migration, or that they cover any considerable distance, such as to
take them from one field to another, during the whole period of their
active larval life.

The May-beetles also seem local in their distribution. Although
very good fliers, they use their wings only to carry them from their
place of origin to the trees and shrubs on which they feed and in
which they copulate at night, and from these to their daytime hid-
ing places, never moving in swarms, so far as known, or migrating
over considerable distances. ‘There is, in short, no evidence of any
migration movement of this insect in any stage or under any cir-
cumstances, but each locality or considerable neighborhood prob-
ably breeds and maintains its own white-grub population year after
year. Their most marked movements are the evening flight of the
beetles to their food plants, and the morning dispersal from trees
to the fields in which the females lay their eggs.

The discovery that certain species, at least, of the May-beetles
may feed, and sometimes do feed to a small extent, on corn and
grass, and the consequent conclusion that they may not need con-
venient access to trees for food, raises the important question
whether some of these insects, and possibly certain species of them,
may not live continuously in the fields, feeding on the crop plants
there and laying their eggs in the very places where they themselves
originated. If this is the case, collections made in the fields at max-
lium distances from trees should give us proof of the fact; and I
consequently arranged, in the spring of 1906, for the systematic use
of lantern traps distributed over an open area of one hundred and
sixty acres on the main farm of the University of Illinois, with trees
of various sorts in a cemetery along one side of this tract, and no
others within less than half a mile from it in any direction. These
traps were ordinary kerosene lanterns, with glass globes, placed
over large tin trays, each containing kerosene to a depth of about
half an inch. ‘These trays were not large enough to secure all the
beetles which flew against the lantern globes, but they nevertheless
gave satisfactory samples of the beetles flying in the field.

147

The accompanying plat shows the crops of this tract and the dis-
tribution of the lantern traps in each. Forty acres were in corn,
seventy acres in grass, thirty acres in clover and alfalfa, and twenty
acres in oats. ‘Iwo of the lanterns were in corn fields, two in clover

Plat showing Distribution of Light-traps.

Cemetery

Road Road

Old pasture

New pasture

20 acres @ 40 acres

Alfalfa ® Clover

20 acres 10 acres

Corn
a
20 acres

and alfalfa, one in oats, and seven in meadows and pastures of grass.
None were nearer than a quarter of a mile to trees on whose leaves
the May-beetles were feeding at the time, nor farther from them
than three quarters. To avoid attracting beetles from these trees,
each lantern was provided with a tin shade by which its light was
hidden on the side towards the trees nearest to it. These lights were

Corn
20 acres
Meadow grass

10 acres

143

kept burning all night for fourteen nights between May 20 and June
23 inclusive, and were visited at frequent intervals during each of
these nights. The weather was so cold during four nights that the
May-beetles were not flying, and no account is taken of these nights
in this discussion.

The total product of the twelve traps, thus maintained for ten
entire nights, was 142 specimens of May-beetles of the genus Lach-
nosterna and 25 specimens of Cyclocephala. No account is taken of
the latter because their food habits are very different from those of
Lachnosterna. ‘The average product of a lantern in one night was
only 1.2 of the true May-beetles (Lachnosterna), and the largest
catch of any one night was 40 specimens on June 18, or 3% per light.
The largest collections were made on three nights between June 9
and 18 inclusive, these averaging 33 per night, or about 3 to each
trap. The two collections of May, made on the 26th and 31st of
the month, averaged only 6 beetles per night, or I to each two traps.

A single light-trap of the same kind, exposed at night without a
screen, for ten minutes May 21 and for thirty minutes May 23, close
to willow-trees at the border of this field and near the cemetery
above mentioned, yielded 11 May-beetles on the first night and 127 on
the second—seventy times as many taken in ten minutes by one trap
near these trees as were taken at approximately the same date by a
trap exposed all night in the open field. There could be no question,
consequently, that very nearly all the May-beetles of this neighbor-
hood were concentrated in the trees at this time.

New data have been obtained by our collections and observations
of recent years with regard to the nightly movements of the beetles,
and these are thus summarized by Mr. J. A. West, who had charge
of this work for 1906.

“There is a regular migration of beetles from the fields to the
trees in the evening. It takes place in June just about dusk—from a
few minutes before to a few minutes after eight p.m. The move-
ment of the beetles is almost simultaneous from the different fields.
An observer in one field can scarcely move to another and hope to
see the migration. It is usually but a few seconds from the time
its beginnixz is noticed in one place until a companion observer will
report its commencement perhaps a quarter of a mile away. Beetles
were found rising from the ground in fields of oats, in pasture, old
meadow, clover, alfalfa, and in corn. They were most abundant from
old pasture and least numerous from alfalfa and corn. ‘They were
observed coming from the ground in considerable numbers in oats
and clover fields. The following species are mentioned in the order

149

of their abundance: L. implicita, hirticula, ilicis, and rugosa. ‘The
evening migration occupies not over fifteen or twenty minutes, and
* in every instance it seemed completed by 8: 20 p. m.

“While the evening migration seemed to result in a complete
abandonment of the fields by the beetles, yet the observer may now
and then hear a beetle whirr past in the darkness at any hour of the
night, and light-traps so placed in the open field as not to attract
those from the trees will take specimens in small numbers through-
out the night. The beetles distribute themselves regularly over
large areas when they leave the feeding grounds in the morning.
The following is a record of specimens taken in the fields a quarter
of a mile or more from trees, and apparently coming directly from
them: JL. wmplicita, 11, L. hirticula, 5, L. rugosa, 31,—total, 47.

All these specimens were taken by hand, the light-traps not
seeming to attract them.

“The morning movement is very early. It varies considerably,
according to the clearness of the sky. It is so related to the awaken-
ing of the birds that it seems as if the first note of the dick-cissel, or
other early bird, is the signal for the beetles to fly to their hiding
places in the ground. On only two mornings were beetles taken in
June after four o’clock. June 18, a dark cloudy morning, a pair
of L. rugosa were taken at 4: 25 a. m. while in copulation on a stem
of grass. Ordinarily the movement did not last over fifteen min-
utes and it very rarely continued for twenty minutes. On the morn-
ing of June 7, however, a strong wind was blowing thirteen to four-
teen miles an hour from the south. This greatly retarded the
flight of the beetles which had been feeding on trees to the north of
the fields, and on this morning it began at 3:35 o’clock and con-
tinued until 4:10, when the last beetle seen was taken in flight.

“The following notes show the variation in the time of the
morning movement of the beetles according to the brightness of the
morning and its relation to the awakening of the birds :—

“Morning of June 10, moonlight and very bright. Dick-cissel
heard at 3: 08; meadow-lark at 3: 15; kingbird at 3: 20; the follow-
ing, in order given, from 3:25—-3:35,—prairie-chicken, brown
thrasher, quail, robin, and horned lark. On this morning the beetle-
movement began at 3: 18 and lasted until 3: 30.

“Morning of June 18, very cloudy and dark. No bird was heard
until 3: 40, and the movement of the beetles began at 3: 45 and was
complete in ten minutes. About 3: 30 a.m. was the average time for
the first bird note, and 3: 35-3: 45 the regulation time for the morn-
ing movement of the beetles.”

150

These data are of special importance as showing the time of
night when the beetles are accessible in the trees on which they
feed—a subject important to a discussion of measures of prevention
and remedy.

HABIts OF REPRODUCTION.

With respect to the reproduction of May-beetles, we need to
know at what time of day, in what situations, and especially how
soon after emerging, the sexes pair, and when, where, how soon, and
in what numbers the females deposit their eggs. Our definite infor-
mation as to the pairing of the beetles is not abundant, but is suffi-
cient to show that they pair at night on their food plants. The males
are much more active than the females,—a fact illustrated by their
greater abundance at lights in fields at a distance from trees. In
the product of the light-traps used in 1906, as described in this paper

‘under “Movements of Migration and Dispersal’ pp. 146-148),
the males outnumbered the females about 4 to 1, while in collections
made at the same time from trees the number of males was only
39 per cent. of the total number taken. Similar data were given
in my Seventh Report.* It will be seen that it does not follow from
the greater number of females taken on the food plants that females
are actually more numerous than males, but only that the latter are
more widely scattered at night, and more generally on the wing.

It has been noticed by some of the office assistants, and par-
ticularly by Mr. J. A. West, that May-beetles are sometimes very un-
equally numerous in neighboring trees of the same kind, one tree
containing a buzzing multitude while there are comparatively few
on another tree of the same species close by. I have myself once
seen a large tree so full of May-beetles in the evening that the noise
of their movements was like that of a huge swarm of bees, although
the condition of the leaves the following day showed that they had
not resorted to this tree for food. Their assemblage in tree-tops is
evidently in part for breeding purposes, and not wholly for food.

About fifty pairs of these beetles have been taken by us in
copula, all but three of them from trees at night. In one case a pair
of L. rugosa was captured at night by Mr. West from a grass-blade
in a pasture, and two pairs of L. inversa have been seen copulating
in a breeding-cage, also at night. ‘These two pairs had been taken
from earthen cells in the ground October 5, 1905, and transferred to
the insectary, where they at once went into the earth, first appearing
above ground on the rst of the following May. They began to feed

*Eighteenth Rep. State Ent. Il1., p. 117.

151

on elm leaves May 17, and paired at midnight May 25. Our ob-
served dates of copulation all fall within the month of May. ,
The several species of May-beetles may continue active, in a nor-
mal season, from one to two months, reckoning this period from the
first appearance of the earliest specimens to emerge to the final disap-
pearance of the beetles for the year. In our work of 1906 the dates
of first and last appearance of the more abundant species in collec-
tions made regularly near Urbana, at night, from willow, oak, elm,
and cottonwood (Carolina poplar), were as follows: L. implicita,
May 13* and June 28 (46 days); L. ilicis, May 21 and June 23
(33 days); and L. hirticula, May 23 and June 18 (26 days). In
New York, on the other hand, Professor Slingerland some years
ago obtained L. fusca in his light-traps from May 6 to July 5, 1880,
and from May 26 to June 28, 1892; L. dubia from May 8 to July 5,
and from May 30 to June 22; and L. ilicis from June 1 to July 30.

CAPTURES OF LACHNOSTERNA AT LIGHT-TRAPS, OPEN
FIELDS, URBANA, 1906.

& is n

Sie eya Sa sae ee i eae

Attia wes fe VASE ce

Mane 2s cis -Aacais teres oe) oe 4 4 0
Vays svastecycs leiden 6 1 1 5 3
MIMO Vere eit eek Sesto oe ators 8 3 5 6
MISTI Octo cctacave velwer 6 1 3 4 8 6
USBI SVED FON ynee Saas eo eee ae 2, 3 4 i
MITES WO) Miers « wieveuwleraiereereins 18 il 1 2 Uf Z 25 6
nl fila 2000 US Vera MRR Sa oe nae Php 5 24 3
Vite S yes ta cic heresies chetess 16 9 15 40 0
SV tUNeRA OM aie. ovate, sora eueliavertee il 0 1
AUTEN ZG Nyhece asc cuigvene xe erorses a 0 1
BO alia yee cuss Rree tence 76 21 3 5 34 3 ens Dif

Collections made only from the food plants commonly show a
more rapid diminution and earlier disappearance of males than of
females. We may take as an example 2517 specimens of L. implicita
collected from trees on twenty-six different nights between May 14
and June 28, 1906. ‘Thirty-nine per cent. of the specimens taken
during the first thirteen days were males and only 15 per cent. of
those taken during the last thirteen days. On the other hand, in
collections made during the same period by means of lantern traps

*The spring was unusually late this year, and May-beetles did not appear on the wing
until May 13.

152

scattered through the open fields, at a distance from the food plants
of the beetles, the ratio of males to females was precisely twice as
great during the last half of the period as during the first. Slinger-
land’s data, already referred to, do not support the supposition of
a relatively early death of the males.
that females may require repeated fertilization, especially as the
eggs are laid gradually, a few at a time.

It seems likely, consequently,

COLLECTIONS OF LACHNOSTERNA FROM TREES, URBANA, 1906.

Implicita) Fusca
wo <
is] i}
coe ace Be
ele enna ol
May 14..... 59.0 3 aed
iar erates 74) 95) 8 2)
Wary oO zee 27) 52) 5 3
May 17..... | 109} 200) 1
May 21-.... 24) 23)
May 22....| 19} 25)
May 23..... LOB W239 eee eer]
Ways 25) 26
May 25..... 31} 35
May 26.¢..,. | 40%) 135) .f5i-4
May 30..... = Atos ec
Mary: Sisia os 50; 108)
June 1.;... | 24) 125
Jiites: 2 eee 45} 129
HITE? “A vietxe 5 14 96
JUTE o:.es)s 6| 54
times Ogee 4) 36
Alpe ayaee (iyo a 1 9
Fines OAn. | ie
Tpiwe U5. 26. 4) 27
Hine 16... 3 | 17
June 18 :.,. | 12 70
Ne 21 16
June. 22... 3
ine 2oan ee
DUMEZS orcs 1
Totals
Males.... | 834 29
Females.. 1683 aly

ROosTO GATE HOH

| Female

Gibbosa | Rugosa
0
) ses
Be Oar eae
=| a |e
er er eee
10 |
Si eae
i
fs ae |
al oe
3 |
15| 2]
20| 16
1
|
a
| 1
|
|
79 | 66 |
| 23

134

Ilicis |Hirticula| Inversa| Tristis
& i = &
roy el eee | ar S| Sa) s
| 1 e-| 3) @ \eeteele
Pate tteye | eb let alee pes ol IE
1
Ps 1
3 | 14 Silene. at
5 Tia 2 P
13 9) -3 1 1 nl
6 | Sih eal 2
28) 241 45) 21 eV Oshees
MeN S| le 6 5 ik
8 | Slee 4
19| 14 5} 16) 3 1
24| 24/ 12/ 20 P83
BA er Si 5) 3
3 od eo Wee 7\
ISH ( see tox|eee(0) 4
DA 39)" e8si 12
4 ast 2
16 2 BA vot
1 |
1
al
196 136 3 14
145 106, 3) 11

153

Our data show about thirty cases of oviposition by seven of our
species in our breeding-cages, ranging in date from the Ist of June
to the middle of July.* As the beetles have begun to emerge more
than two months earlier, it is likely that they spend some time in
feeding before oviposition begins. In the Eighteenth Report of
this office it is said (p. 118) that the statement commonly made to
the effect that the eggs are laid in a ball of earth is clearly errone-
ous. This assertion must be corrected in the light of numerous ex-
periments made in my insectary in 1906 with May-beetles of several
species, all of which so deposited their eggs in the ground that each
was found inclosed within an earthen ball, a half inch in diameter,
probably formed by the extrusion with the egg of an adhesive fluid
which, upon hardening, held together the particles of earth which it
had penetrated. This method of inclosure was so general that eggs
were most easily found by sifting the dirt in breeding-cages and
breaking open the spherical pellets of earth thus separated. ‘The
eggs were laid at depths varying from not more than an inch to
five or six inches below the surface, the number for each female
varying from 44 for a specimen of L. inversa to 67 for L. implicita.

The following extract from the breeding-cage report of Mr. J.
J. Davis will give additional particulars of interest.

[. inversa. June 12, 1906, 1 female beetle in breeding-cage.
June 18, the earth examined and 44 eggs found, each in a ball of
earth from 3 to 3% inches below the surface. Eggs of a pure milky
color and of an oval shape, measuring 1144 X 2mm. By the end of
three days they had swollen to a nearly spherical form, now measur-~
ing 2X 2%mm. Hatching first observed July 11.

L. hirticula. Beetles collected and placed in breeding-cage June
19, 1906. No eggs were found till July 2, but July 9, 6 were found,
each in its ball of earth. The freshest eggs were white with a
glossy luster. ‘They measured at first from 114 X 2mm. to 2 X 2%
mm. Five days later these eggs had swollen to 2 mm. in diameter,
and were 2% to 234 mm. in length.

L. ephelida. A single egg obtained August 4, 1905, from beetles
collected at Carbondale, Ill., July 26, and placed in breeding-cage
in insectary July 29. This egg was comparatively small and defi-
nitely oval, measuring at first 1144 & 2mm., and later 134 & 2 mm.

L. ilicis. From beetles collected June 19, 1906, eggs were found
in oval balls of earth July 9, none having been present there on the
2d of that month. The eggs were a dull white, quite different from
the glossy luster of those of L. jirticula. They measured at first

*A specimen of L. ephelida, taken July 29, 1905, at Carbondale, in southern Illinois, laid
eggs until August 4,

154

1Y%X 2% to 23% mm., the shorter diameter later enlarging to
2mm.

L. crenulata. From a single female beetle placed in a breeding-
cage July 15, 1905, three eggs were obtained three days later,
deposited at a depth of about an inch. These eggs were oval, measur-
ing 1% to 2% mm. They were white when first laid, but changed
afterwards to cream color.

L. fusca. Eggs were obtained June 22, 1905, from beetles which
had been placed in a breeding-cage April 24. One of these eggs
hatched on the 27th of June.

L. implicita. Adults collected at Elliott, Ill., from cells in the
earth, were placed in a breeding-cage in the insectary October 13,
1905. They were first seen out of their winter quarters April 28,
1906. June 12, 1906, 3 females were alive and 6 eggs were found
by sifting the dirt. On the 20th of June only 1 beetle remained
alive, and this was a female. No more eggs were found up to June
25, but on the 5th of July 42 eggs were sifted out of the dirt, each
in its separate ball of earth. These were from 5% to 6 inches below
the surface. Those most recently laid, measured 1% X 2 to 2% mm.,
while those which were longest deposited measured 2 & 21%4 mm.

RELATIONS TO WEATHER.

The beetles of Lachnosterna transform from the pupa in summer
and fall, remaining, as a rule, in their underground cells, from 2 or
3 to 5 or 6 inches below the surface, unaffected, so far as we know,
by any degree of cold to which they are likely to be subjected in our
climate. Their nocturnal movements after they come out of the
earth are, however, easily influenced by the weather. During thirty-
one nights, commencing May 14 and ending June 28, 1906, these
beetles were studied and collected at Urbana by Mr. West. On five
of these nights no beetles were seen or caught, although the fields,
the lights, and all the best feeding grounds were visited. The rec-
ords of minimum temperature for these five barren nights, and the
rate and direction of the wind, were as follows:

Date | Minimum Temperature 2 ah Soe ae aE ag
ME Aye wl minncretaretevaictors 41° F. N. E.,6to 8 miles per hour
IWiclivg 2S esis rereie’s cleats 42° F, N. E., 4 to 14 miles per hour
Malye 2) eas cele ond 38° F. S. E., 6 to 12 miles per hour
Al fiths=-2 bb ee sero 49° F. N. E., 12 miles, all night
Jitu ew eres utero vets 46° F. N. E., 14 miles, all night

155

No beetles were taken on any night when the thermometer regis-
tered below 52°, except May 21, when the temperature was 62° at
Q p. m. but fell to 46° before morning. A cold rain or high wind
kept them confined at night to their day-time hiding places, and they
were never abundant on their food plants, or flying freely, unless
the minimum temperature was at least 60°. They appeared in great-
est numbers on warm quiet nights following bright sunny days.
The beetles continue feeding during rain if a storm comes up during
a night favorable to their movements; and even their flights are
not wholly suppressed by moderate rain if the weather is warm.

MopDEs AND PLACES OF HIBERNATION.

Our common white-grubs hibernate, in the latitude of central
Illinois, in the two stages of larva and beetle, and in these stages
only. In fifty-seven collections, distributed over several years, ob-
tained by following the plow in fall and in spring, not a single pupa
of these species has occurred, although recently transformed beetles,
still inclosed in their pupal cells, have been collected by the hundred.
The pupa of Lachnosterna may possibly go through the winter now
and then, transforming the following spring, but this is certainly
an extraordinary occurrence in our latitude, quite insignificant as a
factor in the life history of the species. It is also a very unusual
thing for the beetles to come out of the ground in fall. Indeed,
those taken from the earth and placed in breeding-cages in either
fall or early spring, commonly bury themselves without delay. Now
and then a single specimen may be found active in fall, but we have
seen but one such case in the course of our several years’ work. The
beetles are evidently more resistant to cold than the grubs, and do
not attempt, as a rule, to escape by going farther into the ground
with the approach of winter.

During the summer most of the grubs are near the surface of
the soil. A small percentage may be found to a depth of eight or
even ten inches, but the average is about three inches. In late fall
they begin to go down as a protection against the approaching win-
ter’s cold, and may reach a depth of two to two and a half feet. In
October and November, 1905, the downward movement of the
grubs infesting a field of corn, part of which had been completely
destroyed by them, was followed by digging over, on each of five
days, several areas each three and a half feet square, and counting
the grubs exposed. ‘The following table gives the dates at which
this search was made, the average number of grubs found for each
square of three and a half feet, the range in depth of the grubs dug
out, and the average depth for each date.

156

ibe Average Grubs

per Square Range in Depth Average Depth
Oct. 9054...0 292 Near surface to 8 in. Sh5
Oct: 10; 419053. 2. 22.6 Near surface to 10 in. yea!
MCt.. 2a01 90S sia PASS} Near surface to i0 in. 2 isi
Octal Swen. 22. Near surface to 16 in. 6.4
Now) 22,1905. oe 24.75 Three in. to 23 in. LO:

November 22, the last of the above dates, most of these grubs
were from 7 to 14 inches below the surface; but one was found only
3 inches down, seven had stopped at a depth of about 6 inches, and
three had gone to 20 to 23 inches below the surface. The ground
did not freeze permanently until several days after this date.

The grubs approach the surface in spring when the frost leaves
the ground and the soil becomes fit to plow, and one often sees in
the bottom of the furrow the tubular burrows made by them in
coming up from their winter quarters.

PRINCIPAL, ENEMIES.

Swine.—Pigs are by far the most destructive enemies of white-
grubs and of May-beetles. They are extremely fond of these insects,
and of all others within their reach which are large enough to at-
tract their attention, and the diligence with which they will tear in
pieces the sod of an infested pasture, and the depth to which they
will dig in pursuit of grubs in cultivated ground are matters of
common observation. ‘They will also search out and destroy the
‘May-beetles in May and June if allowed to range over pastures and
meadows where these insects hide by day and to which they resort
to lay their eggs. Pigs are consequently our most useful agents for
the destruction of these insects—a point which will be more fully
discussed in this paper under “Measures of Prevention and Rem-
edy.”

Crows and Blackbirds—Next to pigs the most efficient destroy-
ers of white-grubs among our common larger animals are crows
and crow-blackbirds, both of which eat them greedily where they
can find them in sufficient numbers to make them an important ar-
ticle of food. Evidence on this point is less positive with respect to
crows than concerning blackbirds. Mr. W. B. Burrows, of the U. S.
Department of Agriculture, who has studied the food of the com-
mon American crow by examining the contents of more than a
thousand stomachs, reports that he has found white-grubs in a com-
paratively small number of these-stomachs, but that May-beetles had
been eaten by very nearly all the crows taken at a time when these

157

insects were abundant in the beetle stage, making, indeed, the greater
part of the insect food of all the crows collected at that time.

To these well-known facts [ have to add two significant items of
observation reported to me by my field assistants. One of these,
Mr. E. O. G. Kelly, who was engaged during much of the season
of 1906 in a field study of injuries by white-grubs, unusually serious
that year in central Illinois, tells me that he often saw considerable
numbers of crows following after the plow in fall, evidently picking
up white-grubs, and that he has also seen flocks offcrows alight in
a badly infested pasture and tear the sod in pieces in search of the
grubs, fighting with each other for their possession when thus ex-
posed. Another assistant, Mr. A. O. Gross, employed last fall in
collecting data for a census of the bird life of Illinois, found, in a
trip across the state made on foot in September and October, that
next to the horned lark, crows were the most abundant birds on
plowed ground, averaging seventy-nine per square mile in all the
recently plowed fields crossed on that trip. They could have had no
other object there than the search for insect food.*

In a study of the food of blackbirds, made by Mr. F. E. L. Beal
for the U. S. Department of Agriculture in 1894, it was found that
these birds ate either beetles or grubs in every month from March
to October inclusive. In May these insects made more than a sixth,
and in June one ninth, of the entire food. Many stomachs were
found to be literally crammed with grubs; and in many more, grubs
had formed a large part of the previous meal.

The Common Grub Wasp (Tiphia).—Much the most important
insect enemy of the white-grubs is a wasplike insect belonging to the
hymenopterous genus Tiphia. It is a slender, jet-black species, usu-
ally about two thirds of an inch long, but sometimes smaller, and
with wings either clear or more or less deeply tinged with dusky
yellow. It enters the ground in search of the grubs, follows them
up in their burrows, and lays on the back of each grub a single egg,
which hatches in a little over a week into a footless, maggot-like
larva. This larva adheres to the surface of the insect, punctures its
skin and sucks its blood for a time, but finally eats itup. The Tiphia
larva then spins, under ground, an oval brown coccoon within which
it goes through its transformations, coming out as a winged insect
the following summer. ‘The rate of multiplication of the species
is not known, but it is certainly sufficient to enable the Tiphia vir-
tually to destroy, under favorable circumstances, the entire grub
population of a badly infested field.

*“ An Ornithological Cross-section of Illinois in Autumn.” By S. A. Forbes. Bull. Ill.
State Lab. Nat. Hist., Vol. VII., Art. IX., p. 318.

153

The method of the operations of this insect and the main facts
of its life history have been worked out in my insectary during the
past two years by Mr. J. J. Davis and Mr. J. A. West from coccoons
and infested grubs sent in by Mr. Kelly from fields at Elliott, Il.
Thirty-three Tiphia cocoons were used in these observations, twenty-
one of which were obtained November 25, 1905, and twelve April
27, 1906. From those collected in fall the winged insect emerged
at thirteen dates between June 19 and July 28, 1906, and those ob-
tained in spring yielded the adult on eleven dates between June 26
and August 22. ‘These collections consequently do not represent dif-
ferent broods. Only seven of the adults obtained were males, and
twenty-five were females, the sex of one being undetermined.

A pair were seen im copula in one of the breeding-cages at 9 :30
p.m. July 1, and eggs were laid on grubs in the insectary from June
29 to August 21. One lot of young white-grubs brought in Sep-
tember 20, 1906, were already badly infested by very small Tiphia
larve about one eighth of an inch in length. As insectary observa-
tions show that the eggs hatch in from seven to ten days, and that
the young larva reaches the length of an eighth of an inch in about a
week, it appears that the eggs for these larve were laid a little later
than September 1. The period of oviposition of this grub wasp is
thus something more than two months.

In several cases a female Tiphia was induced to go through the
whole operation of preparing her victim and depositing her egg
upon it above ground in a breeding-cage, where she could be con-
tinuously watched, and the facts thus learned are unusually inter-
esting. Like others of its family—the digger-wasps, or Scoliide—
these insects sting their prey before attaching the egg to it, with the
effect to paralyze it more or less completely. Mounting the body of
the grub, which struggles violently against the attack, the Tiphia
seizes with her mandibles the skin of the back just behind the head,
curving her body downward around the side of the grub, with the tip
of her abdomen beneath and just behind the head, and then, after feel-
ing about with the abdomen for a time, finally stings her victim, with
the effect suddenly to quiet its struggles and reduce it to helpless-
ness. Then the 7iphia reverses her position and works the tip of her
abdomen backward and forward for several minutes in one of the
grooves or creases on the back of the larva, usually not far behind the
head, apparently smearing the surface there with a viscid fluid, after
which she deposits her egg on this sticky surface and goes away.*

*The above account is based on insectary observations andexperiments. Several white-
grubs’parasitized by 77phza larve have been found in the field since this was written, and in
every'case the larva,was on the under side of the body between the thoracic legs.

159

The larva, at first almost completely paralyzed by the puncture
of the sting and the venom doubtless injected at the same time,
slowly revives, recovering presently its full powers of locomotion,
so that it is indistinguishable by its behavior from its fellows which
have not been stung. ‘The stinging, in this case, is thus a means of
quieting the struggles of the grub in a way to permit the Tiphia to
attach her egg to its back. Commonly, of course, these operations
go on under ground. A Tiphia introduced into a breeding-cage con-
taining grubs in the earth disappears under ground herself, and does
not come out until she has found and infested a grub.

Repeatedly, where grubs were exposed to attack on the surface
of the dirt in breeding-cages, the Tipiia merely stung them at first,
and then proceeded to bury them before depositing her egg. For
this purpose, she undermined the grub by digging the earth from
beneath it, pulling its body about by means of her jaws until it was
in proper position to enter the hole, gradually digging deeper, and
finally burying it completely. In one case in which the operation
was timed, the grub was buried in ten minutes after it was stung.
Sometimes the 7iphia abandoned an attempt at burial, and left the
grub without placing an egg on it after it was stung.

Apart from that general exhibition of a wonderful adaptation
of its actions to the needs of its prospective progeny which this 77-
pia shares with many other wasps, and especially with those of its
own family, there are two points of peculiar interest in this account
It is an unmistakable fact that the effect of the poisoning of the
grubs by the 7iphia is merely to paralyze the victim temporarily; to
overcome its resistance and reduce it to helplessness while the 7ip/ia
egg is being placed in position. ‘The sting is used as a mere aid in
the struggle of the 7iphia with a stronger insect. ‘This fact may
point to the explanation of the origin of the remarkable instinct of
the solitary wasps to sting and paralyze their prey.

More remarkable still, however, in the light of our present
knowledge of the habits of Tiphia, is its frequent burial of white-
grubs exposed to it on the surface of the ground. Since digger- —
wasps in general are parasites of underground larve only, since the
Tiphia is not known to infest any insects except white-grubs of the
genus Lachnosterna, and since in nature it can never find these
grubs above ground, its deliberate burial of exposed grubs has all
the appearance of a line of action extemporized to meet a previously
unknown condition. Either the 77phia, disturbed at finding its prey
exposed, buries this as a result of impulse aided by intelligent con-
trivance, or we shall find, when its habits are known in full, that it

160

does sometimes normally infest and attack insects exposed above
ground by their habits, burying them as a matter of instinct after
it has placed its egg. Tiphia has not, in fact, been studied as an in-
dependent species, but all the data concerning its habits and life
history have been gathered in the course of studies of the white-
grubs.
The egg of Tipiia remains firmly glued to the back of the chosen
grub, and hatches in seven to ten days. The young larva breaks its
way out from the egg at one end, and, although it begins at once to
feed, it does not at first free itself from the shell, but as it grows
this finally splits and breaks away. When it first emerges the larva
measures slightly more than a millimeter in length. From our scanty
data it appears that it takes about two weeks to get its full growth,
and that it doubles its size in the last two days of its larval life, dur-
ing which it is engaged in devouring the body of its host. Previous
to this time it has been adherent to the skin of the grub whose fluids
it has lived upon. When full grown it is from two thirds to four
fifths of an inch in length.

The cocoons are cylindrical ovate, from 17-22 mm. long, clay-
colored at first, and wood-brown or cinnamon-brown when older.
From our observations thus far made it appears that the larva
hibernates within the cocogn, not pupating until the following
spring. The adult emerges from a little one side of the larger end,
in which it leaves a ragged and irregular opening. In several cases
the abundance of these conspicuous brown cocoons in the earth was
such as to indicate an enormous destruction of white-grubs, and
there is no doubt that this parasite is an important agent in checking
destructive uprisings of these insects.

That this wasp, parasitic on white-grubs, is itself parasitized, is
shown by the results of observations made on 7iphia cocoons col-
lected April 27, 1906, and kept in breeding-cages during the sum-
mer. From these emerged, July 7, 16, and 31, adult bee-flies (Bom-
bylide) of the species Exoprosopa fascipennis, each freeing itself
from the Tiphia cocoon by cutting out a circular piece at the larger
end. The eggs from which these flies resulted were probably laid
on the 7ipiia grub in 1905, before the cocoon was spun.

MISCELLANEOUS INSECT ENEMIES.

Macrophthalma disjuncta.—This little tachinid fly was men-
tioned in my Seventh Report as bred repeatedly from dead white-
grubs, but I was nevertheless uncertain that it was a parasite. Lately
its parasitic nature has been proven by repeatedly breeding it from

161

living grubs kept in breeding-cages in my insectary. Adults have
emerged in these experiments March 26, June 8, July 12, and Au-
gust 8, and others have been taken at electric lights July 9, and in a
corn field September 27. Those appearing March 26 lived in con-
finement until May 14. We have thus seen these insects alive in
every month from March to September inclusive. In the breeding-
cages, remains of a white-grub were commonly found associated
with the cocoon of the parasite.

The adult of this species is a large blackish-gray fly with a gen-
eral resemblance to the common large blow-fly, but with a grayish
white sheen on the basal half of each segment of the abdomen, giv-
ing the effect of equal alternating cross-bands of black and gray.

Ophion bifoveolatum Brullé.—This well-known parasite of the
white-grub has been.reared by us several times from these insects.
In one case the head and skin of a grub were woven into the wall of
the cocoon of the parasite. The species has been bred by us repeat-
edly from cocoons collected from the latter part of July to the first
of September, and kept in breeding-cages through the winter, adults
appearing from March 31 to April 27.

The adult is a large, slender-bodied, dark red ichneumon-fly ;
and the cocoon is quite regularly elliptical, a half inch long by a
fourth of an inch thick at the middle, smooth, dull brownish, or
more or less blackish—especially towards the end.

Sparnopolius fuluus Wied.—This bee-fly, which we have some-
times noticed in corn fields and have collected from miscellaneous
sweepings of vegetation in midsummer, also proves to be a parasite
of the white-grub, as shown by breeding-cage work done in 1904—
1906. It was first detected in this relation by Mr. E. P. Taylor, of
my office, who found a white-grub at Elliott, Ill., August 25, 1904,
with a dipterous larva attached to its back. ‘This was placed in an
insectary cage, which was not examined until April 21, at which
time the white-grub had been completely destroyed, and the larva
had completed its transformations. It probably had emerged in the
fall of 1904. A larva of this same species was next collected July
24, 1906, from among corn roots at Effingham, Ill., and was placed
in a breeding-cage to obtain the adult. It pupated August 22, and
emerged as a winged insect September 10. All our open-air collec-
tions of this fly have been obtained in August.

The adult is about as large as a common house-fly, but 1s covered
with erect yellow fur. The pupa is not inclosed in the last larval
skin. Its head bears three large points on each side anteriorly, and
a smaller pair beneath at the base of the mouth-parts. The last seg-

162

ment of the pupa is rather narrowly truncate, with a small slender
spine on each side of the truncation, and a shorter one beneath each
of these. .

Considerable numbers of another species of parasitic larva were
taken by Mr. Kelly at Elliott, Ill, August 29 and September 20,
1906. ‘These were evidently white-grub parasites, as the remains of
the grubs were still clinging to several of them. ‘This species is still
in the larval stage at this writing.

Three yellow coarcate meloid larve were also found by the same
assistant in an infested oats field with the remnants of white-grubs
attached to them, and another was taken in a similar condition Oc-
tober 10. ‘These specimens have not yet matured.

Pyrgota widata Wied.—One of the most interesting parasitic
enemies of the white-grubs is a large, rather unusual-looking fly of
the family Ortalide, noticed by Mr. J. A. West, an assistant of my
office, as abundant among the beetles at night. Now and then May-
beetles were seen to drop to the earth, trying to rid themselves of the
adult flies. which were clinging to their backs, each with the last
segment of the abdomen thrust in between the wings and wing-
covers of the beetle and firmly held in place over the middle of the
abdomen. ‘The flies were apparently thus thrusting their eggs into
tHe backs of the beetles through the thin dorsal skin beneath the
wing-covers. ‘The tip of the abdomen of the female fly is admirably
adapted to this object, being hard and subconical, and directed down-
wards at a right angle to the axis of the body.

The relations of these insects were experimentally determined
by confining, June 9, 1906, adult May-beetles in a breeding-cage
with several of the flies. ‘These would light on the backs of the
feeding beetles, which would at once drop to the ground with the
flies clinging to them. Whenever a beetle spread its wings for flight
the insect on its back inserted the tip of its abdomen between the
May-beetle’s wings, evidently depositing an egg in its back. Beetles
so treated lived for some days, and then began to die. On the 27th
of June, five of the beetles were dead, and in the bodies of two of
these, dipterous maggots were found. July Io, three of the beetles
contained each a dipterous puparium, which remained unchanged
until May of this year, when all produced adults of P. undata. Au-
gust 29 and September 20, 1906, several puparia were found in the
bodies of dead May-beetles, and these, kept in breeding-cages
through the winter, produced adults of P. wndata May 14 and 17,
1907. Like experiments begun during the present year have pro-
gressed similarly to the time of writing. Adult flies of this species

163

were again frequently seen June 12 to 18, 1907, among May-beetles
on trees at night, no less than twenty-six specimens being captured.
These flies have also been occasionally taken at electric lights, and
in various situations by day during different years, from May 20
to June 17.

The puparia of these parasites are dull black, broad ovate, widest
at the posterior third. At the tip is a small shallow excavation en-
circled by a rugose ridge, which is elevated latero-dorsally into a
pair of short irregular tubercles, the tips of which are about a milli-
meter apart. Length 7-8 mm.; greatest diameter, 4.5—-4.8 mm.;
diameter of anterior end, about 3 mm. The adult flies are yellow-

brown, three eighths’to half an inch long. The head is subtriangular,

the thorax globose, the abdomen slender at base, enlarging apically.
The wings are three eighths to half an inch long, conspicuously and
characteristically marked. ‘The entire anterior margin of the wings
has a broad brown border reaching half way across the wing, and
having two broad saw-tooth-like extensions attaining the posterior
margin, one at the middle of the apical half and the other at that
of the basal half. The first two abdominal segments are about as
long as broad, and connate; the next four, in the female, are very
short, followed by the genital segment, which is very large, shining,
directed downwards and curved slightly forwards.

The male abdomen is similarly shaped: the two basal segments
are followed by two more about twice as long as the corresponding
ones in the female; the next segment is a little longer than broad,
vertically directed, bearing the genital segment, which is directed
somewhat anteriorly. The eyes are larger in the female than in
the male.

Other Dipterous Parasites —In 1905 a May-beetle of the species
Lachnosterna crenulata found near Urbana July 15, laid three eggs,
and died about the 29th of July. On August 5 an adult tachinid
emerged from the body which Mr. Tyler Townsend, of the U. S.
National Museum, regards as a new species—Viviana. Two dip-
terous larve were found June 27, 1906, in a May-beetle taken alive
May 31. July ro these larve had formed puparia, and adult tachinid
flies emerged May 17 and 18 of the following year. These are
slightly larger than a house-fly, with black subquadrate thorax, the
anterior angles each with a triangular red spot. The puparium is
very dark red, almost black, subcylindrical, with rounded ends.
Length, 7 mm.; width, 3 mm. It is smoothly rounded behind, with
a pair of low tubercles placed close together. The species has not
been determined.

164

RELATION TO Soil, AND SUBSOIL,.

It is a matter of common opinion that injuries by white-grubs
are more serious on the higher, lighter, and drier parts of our culti-
vated areas than on the lower and moister parts, but no exact ob-
sevations have been made to show whether this apparent difference
is real under all conditions, and whether, if so, it is due to a greater
abundance of the grubs on high lands than on low, or to a lesser
average power of recuperation and resistance on the part of plants
growing in comparatively light and less fertile soils.

I began in 1904 and 1905 to accumulate data on this and allied
points, by having collections of white-grubs made by persons follow-
ing the plow, who recorded for each field and situation the number
of grubs found in each quarter of a mile of furrow. A record was
also made, for each field examined, of the succession of crops it had
borne for the five years preceding, of the character of the soil, the
lay of the land, the conditions as to drainage and to fertilization,
and the relation of the field to trees and shrubs on which the parent
beetles of the grubs might have found food. Collections were made
on this plan from seventy-nine fields in the following twelve counties
of central and southern Illinois: Stark, Peoria, Woodford, Mc-
Lean, Champaign, Macon, Macoupin, St. Clair, Washington, Ma-
rion, Jackson, and Union. ‘This work was interrupted by lack of
funds and by diversion of assistants to more pressing problems
before any sufficient mass of data had been obtained to enable me
to draw satisfactory general conclusions on any one of the points of
principal interest. So far as they go, they show that the grubs were
more abundant on the higher and drier parts of the country than on
the lower and moister parts, and that the fewest eggs were laid by
the parent beetles in corn fields and the most in grass-lands. Thirty-
eight low-land fields gave an average of 21 grubs exposed in a mile
of plowed furrow, and 41 of the high-land fields an average of 31 to
the mile. The three largest numbers found in any fields were 208,
164, and 140 grubs to the mile, all on high ground. The largest num-
bers in any of the low-land fields were 112 and 104 in two of them.
Again, the average of fields which had been in corn continuously for
at least three years preceding was 17 grubs exposed in each mile of
furrow, and that of fields which, although in corn at the time, had
been in grass for several years preceding, was 37 grubs to the mile.
It is evident that useful information may be obtained from data of
this description if they are accumulated in sufficient number and are.
properly classified.

165

RELATIONS TO AGRICULTURAL MANAGEMENT.

Injuries by white-grubs are-influenced to a considerable extent
by the system of farming, and especially by the succession of crops;
by the management of pasture-lands, in which, if left wholly to
themselves, they are likely to accumulate in increasing numbers year
by year; and possibly, also, by the time of the year when infested
lands are plowed. While the old idea that white-grubs are essen-
tially insects of pastures and meadows has been exploded by ob-
servations of recent years, it still remains true that, other things
being equal, they are most abundant in grass-lands, and consequently
most injurious to other crops if these follow within one or two
years upon an infested pasture or meadow. They seem particularly
liable to accumulate in an old turf.which has lain unbroken for sev-
eral years, and are less likely to be destructive where there is a quick
rotation of crops, including a short period in grass, to be followed
by one or two years in clover. ‘The modern stockman’s practice of
herding cattle and pigs together is an excellent one from our stand-
point, since the pigs, in following the cattle, are likely also to search
out the grubs in the turf and to keep the sod practically free from
them.

It is a matter of common, though not universal, opinion among
farmers who have watched the work of the white-grubs that fall
plowing of infested lands is preferable to spring plowing. In the
absence of any apparent reason why this should be so, and in the
absence also of any experiments upon the subject and of any consid-
erable number of exact observations, this supposition must be re-
garded as doubtful. Our own field reports give thus far but a single
instance, reported by Mr. Kelly in 1905, of a notable difference in
white-grub injury corresponding to a difference in the time of plow-
ing of different parts of the same field; and this instance is by no
means clear, since there was injury by grubs in both parts of this
field—much greater and more extensive, however, on the spring
plowing. ‘The white-grubs were also reported as less abundant in
the part of the field plowed in fall, averaging there one grub to the
hill of corn as compared with seven to the hill found in the part
plowed in spring. The data of this observation are incomplete, how-
ever, and this difference in number of grubs may have been due to
something else than difference in the time of plowing.

INJURIES TO CROPS.

Injuries to crops by white-grubs and May-beetles are often of the
most serious and extensive character. The beetles by their destruc-

166

tion of leaves of trees and shrubs in spring not infrequently cause
the death of those preferred by them for food, and the grubs are
particularly destructive in towns to the turf of lawns, in nurseries to
young evergreens, in the fruit plantations to strawberry vines, and
on the general farm to grass and corn.

The injury by grubs is due, in all cases, to the destruction of the
roots of the plants infested and the consequent weakening or actual
killing of the plant. ‘The nature and extent of the injury to corn is
well illustrated by observations made by one of my assistants, Mr.
Kelly, in a field near Ludlow, in Champaign county, about ten acres
of which were almost completely destroyed. By digging up to a
depth of twenty inches, and searching all the soil belonging to each
of sixty hills of corn—an area, that is, three and a half feet square
for each hill—it was found that this badly injured area contained
an average of 3,460 grubs to the hundred hills, or more than 34 to
the hill,—a total of about three hundred pounds of grubs to the acre
of corn. The plants varied in height from two inches to six feet,
and the total number of ears borne by two thousand hills was 786,
all small ears or nubbins.

PREVENTION AND REMEDY.

The subject of preventive and remedial measures was somewhat
fully treated in my Seventh Report (pp. 127-137), and there is
nothing important to add to that discussion at the present time be-
yond a statement of the results of an experiment with pigs as a
means of clearing the grubs out of an infested field. ‘This experi-
ment was made in the field above referred to, near Ludlow, IIl., ten
acres of the worst injured part being surrounded with a temporary
fence, and one hundred pigs averaging seventy-five pounds each,
together with eight large sows, being turned into the inclosure Sep-
tember 23.

By October 13 the pigs had rooted over the whole surface of
the ten-acre lot, going, in some places, to a depth of ten or twelve
inches. An area equivalent to twenty corn hills was now examined
to a depth of twenty inches, with the result that an average of 4.8
grubs per hill were found, as compared with 34.6 per hill at the
beginning of the experiment—a benefit of 86 per cent. in twenty
days. ‘The grubs found in the field at this time were usually eight
inches or more below the surface.

The pigs were in this inclosure until October 20, when they were
removed to another badly injured part of the field, and a final ex-
amination of the plot was made. In an area equal to ten hills of

167

corn only two grubs were found—a benefit of over gg per cent. de-
stroyed by the pigs in twenty-seven days. As the grubs were at this
season going down to escape frost, the hogs were burrowing in
pursuit of them, sometimes to a depth of two feet.

Although these pigs remained perfectly thrifty, it is proper to
say that there is one possibly serious objection to this very common
use of swine as a means of keeping in check the white-grubs in grass-
lands and of clearing them out of fields of corn. It has been shown
by Dr. C. W. Stiles, of the U. S. Bureau of Animal Industry,* that
one of the most injurious intestinal parasites of swine, known as
the giant thorn-headed worm (Echinorhynchus gigas), passes one
- stage of its life in certain of the white-grubs, and‘that pigs become
infested by it by devouring infested grubs, which themselves obtain
it by way of the excrement of the pigs. Where either grubs or pigs
become infested by these parasites the situation is more or less dan-
gerous if pigs are allowed to eat the grubs; but pigs which have
never been pastured are certain to*be free from these parasites, and
grubs growing in fields which have not been pastured by pigs are
likewise certain to be free from them. The use of such pigs upon
such fields would consequently be without danger from this source,
and a little attention to these facts will avoid any injurious conse-
quences. ‘That is, if pigs not previously allowed to run out are
turned into fields on which pigs have not been pastured within three
years, there will be no danger that they will become infested by
these thorn-headed worms.

The general measures discussed in my Seventh Report are es-
sentially a destruction of the May-beetles before they have laid their
eggs, and the distribution among the grubs of the germs of their
contagious diseases. Nothing has thus far been done to test the pos-
sibility of the collection and distribution of parasites other than
those of contagious diseases, and the latter subject can not by any
means be said to have been worked out to final conclusions.

The May-beetles may be' destroyed either by spraying repeatedly
with arsenical poisons the trees. on whose foliage they feed; by
shaking or jarring them down in the cooler parts of the night from
the trees and shrubs on which they are feeding, and collecting them
for destruction; and by trapping and killing them at night by means
of lanterns fastened over tubs or traps containing water covered
with a film of kerosene. The grubs may possibly be kept in check
by the distribution among them of the germs of their contagious clis-
eases obtained by artificial cultivation—a method which has been

*“On an American Intermediate Host of Echinorhynchus gigas.’ By C W.Siiles. Zool.
Anz, Feb., 1892, p. 52.

168

used with some success against the white-grubs of France. ‘The
main dependence in the Old World, however, has been a thoroughly
organized movement for the collection of the beetles from the trees
at night, the usual method of securing general action being to pay a
sufficient price for the beetles in quantity to make their collection a
profitable enterprise during the time of their presence on the trees.
‘This method can be used to advantage only by owners of very large
estates or by communities or combinations of farmers acting to-
gether for their common benefit. ‘The same may be said of the
destruction of the beetles by poisoning their food. If the ordinary
land owner were to proceed by himself, it is probable that his fields
would become itfested by invasion from without even though he -
might destroy every May-beetle on his own premises. ‘The least
promising of these methods is the simplest and the cheapest of them
all—that of collecting the beetles by lantern traps. ‘These take ef-
fect much the most strongly upon the males, and collect, under the
most favorable circumstances, only a comparatively small percentage
of the beetles in their neighborhood. Furthermore, it is available
only on dark and relatively quiet nights.

What may be done by way of general concerted action is well
illustrated by a campaign of destruction carried on against the white-
grubs of the Swedish province of Halland during the ten years from
1885 to 1895, within which time 29,736 bushels of May-beetles and
their larvae were collected at an expense of $15,554, or about 52
cents a bushel, the state usually paying half of this sum, the Eco-
nomic Society of the province a fourth, and the communes or coun-
ties the remaining fourth. The effect was especially shown in the
gradual reduction in the number of the beetles collected—from 14,-
Sor bushels in 1887 to 5,611 in 1895, although the number of com-
munes participating in the work had increased in the meantime, and
the area covered by the collections was correspondingly greater.*

So far as is now to be foreseen, organized work of some such de-
scription will finally be necessary to the control of the white-grub
pest in Illinois, and throughout America generally.

*August Lyttkins, in Enutomologisk Tidskrift for 1897. Stockholm, 1398.

PLATE IX

A Common Wurre-crus, Lachnosterna rugosa. Fig. 1 - pupa, length
about % inch. Fig. 2 -egg, diameter about 75 inch. Fig. 3 adult,

length about 34 inch. Fig. 4—larva, about twice natural size.

3

PLATE X

Tue Common Gros- Wasp, Tiphia vulgaris. Fig. 1— larva, about
three times natural size. Fig. 2 —cocoon, length about % inch.
Fig. 3- adult female, length about % inch.

cae’) 7 i A Ai
r rn K Wee
ul TT od “if

-
qe

PIGAC Exel

Fig. 1—Wurre-crus Parasrre, Sparnopolius fulvus, adult; length
about % inch. Fig. 2—A May-reeriy Parasrre, Pyrgota undata,

adult; length about % inch.

ERRATA,

Page 115, in description of Fig, 7 read
¥Y% for %, and in that_of Fig. 8 read ~
slightly more than before natural size.

_ Page 124, line 13 from bottom, for R. M.
Webster read R. L. Webster.

Page 136, line 14, dele inornata. _

_ Page 137, line 8, for gibbosa read gib-
bosus. : :

Maa
Tr Ag

per

7

BIND x:

A

Acer saccharinum, 100, 103.

Agonoderus pallipes, remains of, found in
ants’ nest, 26. “ E
Alfalfa field, light-trap for May-beetles in, 147.

alienus, Lasius, 19, 21, 22, 24, 25, 26.

Allorhina nitida, 137.

Alwood, W. B., 47.

Ambrosia, Corn Root-aphis on roots of, 2r.

American, or White, Elm, injury to, by Elm
Twig-girdler, 118—r2r.

americana, Ulmus, 118.

Ants and aphids, corn hills infested by, 10, 12.
attendant on Corn Root-aphis, 8, 10, 11,

DA eese Ids LOs 317.) DSs.10) 20, 21, 22;
23, 24—26.
eaten by harpalid, 26.

Aphis maidiradicis, field experiments on, 8—
29. See Corn Root-aphis.

Apple as food plant of May-beetles, 143, 144.
infested by Cottony Maple Scale, 103.
-trees flamed with gasoline blast-lamp, 46,

iy Baten Sede

Apples, poison tests of sprayed, 92—94.
spraying, for the Plum-curculio, 78—g9.

See under Plum-curcul'o.
arcuata, Lachnosterna, 137.
Arsenate of lead for Plum-curculio, 82, 92.
for Elm Twig-girdler, 132.
Arsenical poisons for Elm Twig-girdler, 131,
for May-beetles, 167, 168.

Ash, 103.

White, as food plant of May-beetles, 143.

Ashmead, Wm. H., 1209.

Aster flamed with gasoline blast-lamp, 44, 50.

B

balteata, Cymatodera, 128, 1209.

Barrier experiments for protection of Corn
against Chinch-bug, 30—32, 34, 35, 36
—40, 56.

cost of, 57.
Barto, Frank, 14.
Basswood, or Linden, injuries to, by
tony Maple Scale, 102, 103.
Beals: Bae rs 7.
Beech subject to injury by Cottony Maple
Scale, 103.
Bee-flies as parasites of
Wasp, 160.
of White-grubs, 161,

Cot-

Common Grub-

Beetles infesting Aster, gasoline blast-lamp
used against, 44, so.

bifoveolatum, Ophion, 161.

Bill-bugs, timothy, injury to Corn by, 1—7.
See Timothy bill-bugs.

binotata, Hyperaspis, 115.

Bittersweet subject to
Maple Scaie, 103.

bivulnerus, Chilocorus, 11s.

Black Locust subject to injury by Cottony

Maple Scale, 103.

Walnut subject to injury by same, 103.

Blackbirds and crows as enemies of White-
grubs and May-beetles, 156.

Blaing s1Gs, ur36

Blister-beetles killed by gasoline blast-lamp,
54.

Blue-grass as food of May-beetles, 145.
lawns injured by Sphenophorus parvu-

hus, 7s
Bolter, A., 49. -

injury by Cottony

Bombyliide as parasites of Common Grub-
Wasp, 160.

Box-elder as food plant of May-beetles, 143.
flamed with gasoline blast-lamp, 52.
injuries to, by Cottony Maple Scale, 102,

103, 116.
Braucher, R. W., 48, 111, 112.
Brown Thrasher, 1409.

Buffalo-berry flamed with gasoline _ blast-
lamp, 46.

[shovel AD Vag aries).

Burrows, W. B., 156.

3utternut-trees, Jachnosterna beetles col-

lected from, 141.

C

Cabbage-bug, Harlequin.
used against, 43, 48—4o9.
Cabbage flamed with gasoline

Ree
Plusia, gasoline blast-lamp used against, 54.
gasoline blast-lamp used against,

gasoline b’ast lamp

blast-lamp,

-worms,
51, 54.
caliginosus, Harpalus, 26.
Carolina Poplar as food plant of May-bectles,
143.
Carrot-beetle,
Catalpa, 103.
Caterpillars and moths,
used against, 44, 45.

egy

gasoline blast-lamp

Cedar flamed with gasoline blast-lamp, 52.
Cherry and the gasoline blast-lamp, 47, 52.
as food plant of May-beetles, 143.
infested by Elm Twig-girdler, 118, 121.
Chilocorus bivulnerus as enemy of Cottony
Maple Scale, 115.
Chinch-bug, comparative cost of
treatments for, 55, 56.
experiments with fluid
40—43.
field trials with gasoline blast-lamp for, 44,
52—56, 57—58.
injury, barrier experiments for protection
of Corn against, 30—32, 34—40,
565 7-
cost of protection of Corn against, 35,
36, 39, 43, 55, 56, 57-
experiments at Carbondale, Ill., for
protection of Corn against, 33—36.
at Dubois and Odin, IIl., for same,
39—40.
near Fairman, IIl., for same, 36—39.
field experiments for protection of
Corn against, 30—58.
general summary on same, 56—58.
kerosene emulsions and miytures for, 32—
36, 40—42, 53, 55-
or crude petroleum, use for, in dealing
with, 56.
préparation and cost of coal-tar line as
barrier against, 37—39, 57.
of dusty furrow as barrier against, 36—
Bi
whale-oil soap for, 42, 43, 57.
Chittenden, F. H., 119, 137.
Clover, 1.
as substitute for
bill-bugs, 7.
fields, light-traps for May-beetles in, 147.
Coal-tar line with post-hole traps as barrier
against Chinch-bug,. 30, 31, 34, 37—39,

various

insecticides for,

Timothy to eradicate

56—57.

Coccophagus lecanii as parasite of Cottony
Maple Scale, 114.
Colorado potato- beetles

blast-lamp, 54.
Common Grub-Wasp as parasite of White-
grubs, 157-—160. See Grub -Wasp, Common,
Coolidge, J. H., 9.
Corn as food plant of May-beetles, 143, 145,
146.
barrier protection of,
against Chinch-bug injury, 30—32, 34.
bill-bugs in Illinois, article on, cited, 1.
field experiments for protection of, against
chinch-bug injury, 30—58.

killed by gasoline

experiments for

injury to, by timothy bill-bugs (Sphe-
nophorus spp.), 1—7.
extent, general effect, and _ total

amount of, 3—6.
methods of prevention of, 6—7.

Corn, injury to, etc.— Continued.
summary of investigation of, 7.
light-traps for May-beetles in, 147.
nature and extent of injury to, by White-
grubs illustrated, 166.
Root-aphis, additional miscellaneous ob-
servations on, 24—26.
and attendant ants, comparative reduc-
tion of numbers of, 18.
breeding-cage experiments with, and with
eggs of, 26.
comparative tabular exhibit of results of
treatment of ground for, 29.
early treatment of soil for control of,
26.27.
effect of drouth on attack of, 19.
of once and twice disking ground for,
27, 28, 29.
on, of change of crop from Corn to
Oats, 20—24, 28.
field experiments on the, 8—29.
in 1904, 8—13.
in 1905, 13—26.
Finnegan cultivation
19—20.
tabular abstract of, 20.
Galesburg cultivation experiment for, 9
—Il.
tabular abstract of, 11.
general discussion of results of cultiva-
tion experiments for, 26—29.
Harvel cultivation experiment for, 11—
13;
tabular abstract of, 13.

experiment for,

Hinman cultivation experiment for, 15
—I9.
tabular abstract of, 17.

in plots receiving different cultivation
and planted at various dates, 18.

life history of, 8.

observations on, in

23—24.

on Barto farm, 20—23.

periods and _ succession of generations
of, 26.

ratio of winged to wingless specimens of,
19, 22; 23, 24.

scattering eggs and young of, in early
spring, 8.

various operations on ground in culti-
vation experiments for, 9.

Cotton Boll-weevil, gasoline blast-lamp used
against, 44, 49.

Cottonwood as food plant of May-beetles, 144.

Cottony Maple Scale, articles on, cited, 116.

comparative effectiveness of winter
and summer treatment for, 116.

effect of summer spraying of trees

for, 108, 110.

of infestation by, on trees, 102.

food plants of, 103, 116.

Thompson field,

a

Cottony Maple Scale—Coxtinued.

hatching period of, 106.

history of, in Illinois since 1867, 100—
102.

Illinois counties reported as
by, in 1905, 102, 116.

in Illinois, 100—117.

infestation by, in Chicago and certain
suburbs of, 100, 103, 115.

injuries by, commonly periodical, 100,

infested

Tn Ss
injury to trees when spraying for,
I12—II4.
insect enemies of, 100, 102, 114—II5,
Tits
kerosene emulsion for, 106—114, 116.
life history of, 104—105, 116.
protection of roots of trees treated

with kerosene emulsion for, 113, 116.
summary concerning, 115—117.
summer insecticide measures for, 106

—IIc.
table giving data and results of ex-

perimental summer-spraying for, 109.

test of death of, 107.

whale-oil soap solution for, 108, 109,
110.

winter insecticide measures against,
IIO—II2.

Craig, John, 44, 46.
Crambus, gasoline blast-lamp used against, 51.
Crandall, C. S., 80. i
crenulata, Lachnosterna, 154, 163.
Crows, abundance of, on plowed ground, 157.
and blackbirds as enemies of White-grubs
and May-beetles, 156—157.
Cyclocephala, food habits of, 148.
immaculata, 137.
injurious species of, found in Illinois, 137.
Cymatodera balteata, description of beetle of,
129.
of larva of, 130.
larva of, preying upon larve of Elm
Twig-girdler in burrows, 128.
notes on life history and distribution of,
129—1I30.

D
Dalbey, D. S., 1.
Dalbey, Wm. M., i
Davish JeeNes) U24e. 15a 15
Dawson, W. N., 128.
Dehn, Wm. M., o2.
Deyo, E. P., and Foster, L. I., 13.
Dick-cissel, 1409.
Digger-wasps as parasites, 158, 159.
Dipterous parasites of May-heetles, 163.
Diseases of White-grubs, 136.
disjuncta, Macrophthalma, 160.
Doerr. A. 11,

Dogwood, 1r2r.
Cottony Maple Scale found on, 103.
flamed with gasoline blast-lamp to destroy
San Jose Scale, 46.

dubia, Lachnosterna, 139,

DAT DSL

1B,

Earthworm, Lasius alienus feeding on, 26.

Echinorhynchus gigas as parasite of pigs and
White-grubs, 167.

Kggs of Common Grub -Wasp, 157, 158, 159,

160.

of Corn Root-aphis, 8, 14, 16, 20, 21, 22,
DAeZS

of Cottony Maple Scale, 104, 106, 115—
P16, I17-

of Elm Twig-girdler, 118, 119, 120, 121,
T22, 123, T2445 1260; 127.

of White-grubs, 137, 138, 139, 146, 150,

TAs aneisy, aueyle, atleyio
Elm, American, or White, injury to, by Elm
Twig-girdler, 110—re2r.
as food plant of May-beetles, 143, 144, 145.
flamed with gasoline blast-lamp, 52.
infested by Oberea sp., 127.
injuries to, by Cottony Maple Scale, 102,

TO3s TO:

Red, apparently immune from injury by
Elm Twig-girdler, 121.

Twig-girdler, 118—134.
best time to begin to spray for, 133.
description of, 133—134.
distribution of, 127—128.
hibernation of, 124.
insectary notes on, 124—125.
life history and habits of, 122—127.
manner of feeding of adult, 126.
natural checks on multiplication of,

128—13I.
nature and extent of injury by, 120—
Te.
Oviposition of, 122, 126, 127.
period of injury by, 121.
protective measures against, 131—133.
pupation of, 123.
recognition of injury by, 119.
Ilms, Lachnosterna beetles collected from,
141.

ephelida, Lachnosterna, 153.
Epicauta marginata killed by gasoline blast-

lamp, 54.
Fuderus lividus, description
pupa of, 129.
larva of, preying
Twig-girdler, 128.
Iivergreens liable to injury by White-grubs,
166.
Exoprosopa_ fascipennis as parasite of Com-
mon Grub -Wasp, 160.

of adult and

upon larve of Elm

Xi
F
Fall web-worms, gasoline blast-lamp used
against, 51.
False Syringa, mature egg-laying cottony |
maple scales found on, 103. |
fascipennis, Exoprosopa, 160.
Finnegan, Edward, 14.
Folsom, J. W., 9, 10, 102, 103, 106, 108.
Forbes Scale, gasoline’ blast-lamp used

against, 51.
Foxtail-grass,
16, 26:

fulvus, Sparnopolius, 161.

Fungus parasites of the green leaf, gasoline
blast-lamp used against, 44, 51.

fusca, Lachnosterna, 137, 138, 139, 140, I41,

Corn Root-aphis feeding on,

142; 143; Idd, TST B52h 15A-
G
Gasoline blast-lamp for general insecticide

purposes, 45, 47, 52.
effect of, on various trees and plants,
46—48, 52.
experiments with, 50—52.
for destruction of fungus parasites,

44, 51.
for destruction of insects, 43—56,
: 57- :
used against Chinch-bug, 44, 52—56,
57—58.

against Cotton Boll-weevil, 44, 49.
against Harlequin Cabbage-bug, 43, 48
—49.
against San Jose Scale, 44, 46—48.
for burning thorns from prickly pears,
44.
Gastman, FE. A., 118.

Giant Thorn-headed Worm as parasite of
pigs, 167.
gibbosa, Lachnosterna, 137, 139, 140, I41,
142, 143, 144, 152.
Ligyrus 137.

gigas, Echinorhynchus, 167.
Gillette, C. P., 94.
Gossard, H. A., and Osborn, [Herbert, 6.
Grape-vine subject to injury by Cottony
Maple Scale, 103.
Grass as food of May-beetles, 143, 146.
Grasses flamed with gasoline blast-lamp, 52.
Green June-bug, 137.
Gross;-Au Ospasy.
Grub -Wasp, Common, as parasite of White-
grubs, 157—160.
dates of collection of cocoons of, and
emergence from, 158.
description and abundance of cocoons
of, 160.
general description of,
mations of, 157.
hibernation of, 160.

and_ transfor-

ee

Grub -Wasp, Common—Continued. — . :

insectary observations on, 158—159.
Oviposition of, 157, 158.
parasites of, 160.

period and mode of oviposition of, 158.

stinging and burying of exposed White-
grubs by, 159.

H

Harlequin Cabbage-bug, gasoline blast-lamp
used against, 43, 48—4o.

Harpalid devouring ants, 26.

Harpalus caliginosus found in nest of La
sius alienus, 26.

Hart, ©, vAt) 102;1a7"

Hawthorn subject to injury by Cottony Ma-
ple Scale, 103.

Hickory-trees, Lachnosterna beetles collected —

from, 141.
Hinman, HSB aa) os.
hippocastani, Melolontha, 137.
hirticula, Lachnosterna, 137, 138, 139, 140,
I4I, 143, 144, 149, 151, 152, 153.
Honey-locust subject to injury by Cottony

Maple Scale, 103, 116.

Honeysuckle, mature egg-laying cottony ma-
ple scales found on, 103.

Horas eGes ai. 130:

Horned Lark, 149.

Horse-chestnut, mature egg-laying
maple scales found on, 103.

Howard, L. O., 103, 106.

Hymenoptera, parasitic, 128, 136.

Hyperaspis binotata as enemy of Cottony
Maple Scale, 115.

cottony

I

ilicis, Lachnosterna, 137, 139, 140, 141, 14300

1440407 USS ens 3:
immaculata, Cyclocephala, 137.
implicita, Lachnosterna, 137,
141, 143, 144, 149, 151, 152,
innumerabilis, Pulvinaria, 100.
inversa, Lachnosterna, 137, 138, 139,
I4l, L43, 144, 045, 150, 150, 152, 05S-

J

Johnson, S. A., 103, 108, 113, 114.

Jones. EeowW.,. 3:

June-bug, Green, 137.

June-bugs. See under White-grubs and Lach-
nosterna.

138,
153;

139,
154.

140,

140,

K

Kelly, E: (O. Goo rae 2a) 262 rrr. sire,
158, 162, 165, 166.
Kerosene emulsion and gasoline blast-lamp,
55—56.
and mixtures
40—42.

157)

for Chinch-bug, 32—36,

us

bie
X111

Kerosene emulsion and mixtures— Continued.
for San Jose Scale, 59.

and whale-oil soap solution, comparative

cost of, 43, 57.
cost per gallon of ten per cent., 110.
for Cottony Maple Scale, 106—114, 116.
formula for, and directions for making,
Tir, 116—117.
injury to trees by, 108, 112—114.
Kingbird, 140.

13

Lachnosterna, 135—168.
arcuata, article on, cited, 137.
reared from egg to adult, 137.
beetles, collections of, at lights and on
trees compared, 139—140.
at lights in given locatities in differ-
ent years compared, 140, 141.
comparative collections of, from differ-
ent food plants, 144.
dissections of, to determine food of,
144—145.
evening flight and morning dispersal of,
146, 148—150.
habits of reproduction of, 150—154.
oviposition of, general and specific notes
on, 153—I54-
period of activity of, 151.
ratio of males to females in collections
Orie wWisity tl,
crenulata, 154, 163.
dubia, 139, I41, 151.
ephelida, 153.
MUSGA Iss 13S 1S0) LAO, Myr.) T42) 1435
144,050, 2052, Usd.
gibbosa, 137, 139, 140, I4I, 142, 143, 144,
152.
hirticula, 137, 138, 139, 140, I41, 143, 144,
149, 151, 152, 153.
HiCIss) Wa7q 0395. 140; S141.) TAg0 144, 140;
“TG GS 2he GAS
implicita, 137, 138, 139, 140, 141, 143, 144,
149, I51, 152, 153, 154.
injurious species of, found in Illinois, 137.
inversay 1397; 196, 0305, 240, 041, 143, 144,
TA5¢ LS0,. U5 a, D52) 15a:
life histories of injurious
137—140.
rugosa, 137, 139, 140, T4I,, 143, 144, 145,
TAG YDSO ces 052.
species, modes and places of hibernation
of, in central Illinois, 155—156.
variation in numbers.and dominance of,

species of,

I40—142.
tristis, 137, 138, 139, 140, 141, 143, 144,
152.

(See also White-grubs.)

Ladybug, Twice-stabbed, as enemy of Cot-
tony Maple Scale, 11s.

Ladybugs as enemies of same, 115—II7.

Lark, Horned, 149.

Lasius alienus, 19, 21, 22, 24, 25.

- feeding on earthworm, 26.

niger alienus, 14.

lecanii, Coccophagus, 114.

Ligyrus gibbosa, 137.
relictus, 137.

Lilac as food plant of May-beetles, 143.

Linden, or Basswood, injuries to, by Cot-
tony Maple Scale, 102, 103, 116.

Liriodendron as food plant of May-beetles,
143.

lividus, Euderus, 128.

Locust, Black, subject to injury by Cottony
Maple Scale, 103.

Lyttkins, August, 168.

M

McHenry, S. A., 43, 48.
Macrophthalma disjuncta as
White-grubs, 160.

general description of adult of, and in-
sectary notes on, 161.
maidiradicis, Aphis, 8.
Mally, C. W., 44.
Maple, Hard, 103.
Soft, injuries to, by Cottony Maple Scale,
102, 103, II6.
marginata, Epicauta, 54.
May-beetles. See L[achnosterna beetles and
White-grubs.

Meadow-lark, 140.

Meloid larve as White-grub parasites, 162.

Melolontha vulgaris and M. hippocastini, life
cycles of, 137.

monilifera, Populus, 143.

Muck-worm, 137.

Mulberry, Cottony Maple Scale found on,
103.

parasite of

N

Nason, Wm. A.,°129.

Nasturtiums flamed with gasoline blast-lamp,
noe

niger alienus, Lasius, 14.

nitida, Allorhina, 137.

O

Oak as food plant of May-beetles, 143, 144.
injury to, by Cottony Maple Scale, 103.
Oaks, Lachnosterna beetles collected from,

I4I.
Oats, effect on Corn Root-aphis of change
of crop from Corn to, 20—24, 28.
fields abandoned by Corn Root-aphis, 23.
Oberea sp., 127.
tripunctata, 127—128.
ulmicola, 118—134.
Ophion bifoveolatum as parasite of White-
grubs, 16r.

Ortalide, 162.
Osage Orange as food plant of May-beetles,
143-
flamed with gasoline blast-lamp, 52.
Osborn, Herbert, and Gossard, H. A., 6.

P

pallipes, Agonoderus, 26.
Parasites:
of Common Grub -Wasp, 160.
of Cottony Maple Scale, 114.
of Elm Twig-girdler, 128.
of May-beetles, 162, 163.
of swine, 167.
of . White-grubs, 136, 157, 160, 161, 162,
163, 167.

Parasitic Diptera, 163.
Hymenoptera, 128, 136, 157.
Paris green, spraying apple-trees

Plum-curculio, 80.
parvulus, Sphenophorus, 2, 7.
Peach as food plant of May-beetles, 143.
infested by Cottony Maple Scale, 103.
by Elm Twig-girdler, 118, rar.
-trees flamed with gasoline blast-lamp to
destroy San Jose Scale, 46, 47, 52.
liable to injury by Cottony Maple
Seale, 103.
-burner, 49.
-trees flamed with gasoline blast-lamp to
destroy San Jose Scale, 46.
Pears, prickly, gasoline blast-lamp used to
burn thorns from, 44.
Pecan as food plant of May-beetles, 144.
persicaria, Polygonum, 24.
Persimmon as food plant of May-beetles,
144. j
Petroleum, crude, for destruction of chinch-
bugs on ground, 56.
for San Jose Scale, 59.
Petts, “RJ HE, 43. 46, 48:
Philadelphus, mature egg-laying cottony ma-
ple scales found on, 103.
Phillips; Je dy0 4450 47:
Pigs as enemies of White-grubs and May-
beetles, 156, 165, 166—167.
Pine flamed with gasoline blast-lamp, 52.
Plum as food plant of May-beetles, 143.
-curculio, cost of experimental sprayings
for, 91. :
experiments in 1904
sprays for, 80—g2.
insecticides and apparatus used in ex-
perimental spraying for, 82.
outline of articles on, 78, 79, 8o.
of insecticide experiments in 1885 for
protection of apples against, 78—79.
poison tests of apples sprayed with ar-
senate of lead and other insecticides
for, 92—94.

with, for

Pear

with arsenical

Plum-curculio—Continued.
results of experimental
82—og1.
spraying apples for, 78—99.
summary of results of spraying apples
for, 92.
superficial injuries to apples by, as in-
direct cause of disease, 78.
commercial importance ot, 78.
flamed with gasoline blast-lamp to destroy
San Jose Scale, 47, 52.
infested by Cottony Maple Scale, 103.
Polygonum, Corn Root-aphis on roots of, 21.
persicaria, 24.
Poplar, Carolina, as food plant of May-
beetles, 143, 144, 145.
subject 1o injury by Cottony Maple Scale,
103.
Poplars, Lachnosterna beetles collected from,
141.
Populus monilifera as food
beetles, 143.
Potato-beetle, Colorado,
blast-lamp, 54.
Common, and larva, gasoline blast-lamp, 56.
Prairie-chicken, 149.
Pulvinaria innumerabilis, 100.
Pyrgota undata as parasite of May-beetles,
162. ’
pupa and adult of, described, 163.

Q

sprayings for,

plant of May-

killed by gasoline

Quail, 149.

R

Ragweed, young of Corn Root-aphis on roots
Of) 2iy nese
Raspail, Xavier, 137.
Raspberry refused as food and _ breeding
plant by Elm Twig-girdler in confinement,
T2T.
Red Elm apparently immune from injury by
Elm Twig-girdler, 121.
Reeves, G. I., 44, 50.
relictus, Ligyrus, 137.
Remedies and preventives for insect depre-
dations: agricultural f actice, 6, 7,
165.
arsenate of lead, 82, 92, 93, 94, 132.
arsenical poisons, 131, 167, 168.
coal-tar line with post-hole traps, 30, 31,
34, 35, 37—39, 56—57.
crude petroleum, 56, 59.
destruction of beetles before eggs are
deposited, 167—168.
of fallen fruit, 80.
of infested twigs, 131.
distribution of disease germs, 167.
dusty furrow, 30, 34, 36—37, 57-
early and repeated stirring of ground
in spring, 8.

ne we

Remedies, etc.— Continued.
early fall plowing, 6.
gasoline blast-lamp, 43—56, 57, 58.
jarring or shaking beetles from
and destroying, 167, 168.
kerosene emulsion and mixtures, 30, 31,
32; 4042) 55-56, 57, 59, 106—i114,
116.
light-traps, 167, 168.
midsummer plowing and harrowing, 8o.
Paris green, 80.
pasturing with pigs, 156, 165—167.
28.) 105.

trees

rotation of crops, 20—24,

whale-oil soap solution, 2idoe LOS,
109, I10. :
Robin, 149.
Rose-bushes flamed with gasoline blast-lamp,
52.
Rotation of Corn and Oats for Corn Root-
aphis, 20—24, 28.
rugosa, Lachnosterna, 137, 139, 140, 141,
143, 144, 145, 149, 150, 151, 152,
S
saccharinum, Acer, 100, 103.
San Jose Scale, Bowker’s ‘Tree Soap” for, 74.
“SCalcothion’ | for, °70; 72s 735.755 70;
Gas
California washes for, 64—66, 67,
60;) 70; 7%. 76:
caustic-soda solution for, 74.
“Con Sol? fon) 70) 725.735 70.
cost of materials contained in vari-
ous insecticides for, 74—76.
“Frutolin” for, 73.
gasoline blast-lamp used against, 44,
46—48.
kerosene and lime mixture for, 73.
mixtures and emulsions for, 59.
lime and sulphur mixtures for, 62,
63—72, 76.
sulphur, and soda mixture for,
68—69, 70, 71, 72, 76.
Oregon washes for, 66, 67, 69, 70,
71, 72) 73, 76.
“‘Scalecide” for, 70, 73, 76.
“Tak-a-nap’’-soap solution for, 7o,
73—74-
whale-oil soap solution for, 70, 73—
74; 76.
Sanderson, FE. D., 44, 48, 49.
Scale insects, gasoline blast-lamp used
against, aq.0 455. 5'l-
Scoliide, 158. ;
Scurfy Scale, gasoline blast-lamp used

against, 51.
Setaria, Corn Root-aphis on, 26.
Shinn, James R., 8o.
Simonds, ©; €., roz2, 108.
Slingerland, M. V.,.47, 141, 151, 152.

Smartweed, corn roct-aphids on, 14, 16.
root-lice on roots of, 21.
Smartweeds, 23, 24,
Smiths ie bes, ate
Smoke-tree, Cottony Maple Scale on, 103.
Snowberry, infested by same.
Sparnopolius fulvus as
grubs, 161—162.
Sphenophorus parvulus
grass lawns, 7.
infesting roots of Timothy, 2, 7.
probable injury to Corn by, 2.
spp., injury to Corn by, 1—7.
Timothy bill-bugs.
Spire, Cottony Maple Scate found on, 103.
Stanton, J. W., 48.
Stedman, J. M., 43, 40.
Stiles, C. W., 167.
Strawberry-vines liable to injury by White-
grubs, 166.
Sumac subject to injury by Cottony Maple
Scale, 103.
Symons, Thomas B., 44, 47, 48, 50.
Syringa, False, egg-laying
maple scales found on, 103.

25.

parasite of White-

destructive in blue-

See under

mature cottony

aL

Tachinid parasites of White-grubs and May-
beetles, 160, 163.
Mavlor eee LAN stensss (O0;9 Sis) I1S,0 220),
Tene Os 26, Te, TOL.
Thompson Estate, F. H., 14.
Thrasher, Brown, 149.
Timothy, 1.
bill-bugs, field injured by, 1—2.
measure to lessen injury to Corn by, 3.
methods of preventing injury by, 6—7.
(Sphenophorus spp.), injury to Corn by,
I—7.
injury to, by corn bill-bugs, 2.
Tiphia as parasite of White-grubs, 136, 157—

160. See Grub-Wasp, Common.
Titusse Ese ioe (Ge. Te 4s 5 Oye On, lost
122, 123.

Torrence, Frank, 118.

Townsend, Tyler, 163.

Trees and shrubs, injury to, by May-beetles,
166.

tripunctata, Oberea, 127.

tristis, Lachnosterna, 137,
143, 144, 152. .

Trumpet-creeper, mature egg-laying cottony
maple scales on, 103.

Tucker, Edward, 60.

Tulip-tree as food plant of May-beeties, 143.

Twice-stabbed Ladybug as enemy of Cottony
Maple Scale, 115.

Twig-girdler, Elm,
Twig-girdler.

138, 139, 140, 141,

118—134. See’ Elm

° habits of, 142.
injuries to crops by, 165—166.
(Lachnosterna), on the life history,
habits, and economic relations of the,
135—168.

xv1

U

ulmicola, Oberea, 118.

Ulmus americana, 118.

undata, Pyrgota, 162.

U. S. Department of
of Entomology, 7.

University of Illinois,
of, 92.

Agriculture, Division

Chemical Department

Vv

Vasey, Robert W., 107.

Virginia Creeper subject to injury by Cot-
tony Maple Scale, 103.

Viviana sp. as parasite of May-beetle, 163.

vulgaris, Melolontha, 137.

W

Walnut, Black, subject to injury by Cottony
Maple Scale, 103.
flamed with gasoline blast-lamp, 52.
Warder, Reuben H., 102, 112.
Webster, F. M., 6, 44, 118, I19, 124, 127.
Webster, R. L., 124.
Weed, C. M., 94.
Weed, H. E., 6, 100, 103, 106, 107.
West, J. A., 148, 150, 158, 162.
Westcott, O. S., 140, 141, 142.
Whale-oil soap solution and kerosene emul-
sion, comparative cost of, 43, 57.
for Chinch-bug, 42, 43.
for Cottony Maple Scale, 108, 109, 110.
Wheat, 1.
White Ash as food plant of May-beetles, 143. |
-grubs and May-beetles, food and feeding

White -grubs and May - beetles— Continued.
migration and dispersal of, 145—150.
miscellaneous insect enemies of, 160—

163.
preventive and _ remedial
against, 166—168.
principal enemies of, 156—160.
articles on, cited, 136, 137, 167.
concerted action against, 168.
difference in time of plowing ground in-
fested by, 165.
diseases and enemies of, 136, 167.
economic species of, 136.

extent of destruction of, by Common
Grub -Wasp, 160. 3

food preferences of adults of, 142—145.
life cycles of two European species of,

measures

re
life- histories of injurious species of,
137—140.
relations of, to agricultural management,
165.

to soil and subsoil, mode of collect-
ing data on, 164.
results of experiment with pigs for, 166
—167.
(See also under Lachnosterna and Cy-
clocephala. )
American, Elm, injury
Twig-girdler, 118—121.
Willow as food plant of May-beetles,

or to,

by Eutk

143,
144.
subject to injury by Cottony Maple Scale, ~
103. =

Wistaria, mature egg-laying Cottony Maple

Scale on, 103.
Woolly Aphis, gasoline blast-lam) used
against, 51. y

bears, gasoline blast-lamp used against, 5.

ae ae eee

a |
'
ra
is
i
4

pacing seal a erat:

> hated sie eae! te

—————

EWENTY-FIF TH REPORT

STATE ENTOMOLOGIST

ON THE

| Noxious and Beneficial Insects

OF THE

STATE OF ILLINOIS

FOURTEENTH REPORT OF STEPHEN A. FORBES

1909

AON 00 jan ett :
x luge

y Ce,
DEC 16 1809
MARGE

5

ae &

$7.

ue Te

*

EWEN TY-FIFTH REPORE

STATE’ ENTOMOLOGIST

Noxious and Beneficial Insects |

* OF THE

ple OP: TL EINGKS

FOURTEENTH REPORT OF STEPHEN A. FORBES

1909

———
9

CONTENTS
PAGE
(OAL ASG 2/8, en rR ec me Vv
Experiments with Repellents against the Corn Root-aphis, 1905 and 1906..... 1
MEpeMenteapplcations to: the Seed... cc... a eles ac sie cars dendasic ceennyels es ara 2
Syne [RSen cies i) MO 0 Aen iii Aine ae One Bee Rag aria coast TEE hee 2 Xe) 3
Slbea by (al aitpeeoUitul tana Ta vehi. 3c lots n.d scfcvctotei se ene org ast eee oe Re ee a roe 5
acre MmapFe RCNA LAO Sy)! 25 oars sa leas 62/04 gsc Saeed he SULTS RE ae Sacre 7
Pans eae OT AAR ETT ATS 8 005 225" Soe Leia ave cassis “wis vav'nlares' al Oisiah doweteramnEn REG elarals Gini erataiats 12
Aa woriokieldersenerime#nt: [9Q06l.0: » oe cccscecln eee een oe nee aoe 13
siiicmmperimentale Mireles fos) «cco eos c, «va a eke ee tenis Se ime rece itner ere woe 14
ince mpnrsesetcian Ol Bield £0... h! os seals Sore an ocean ernie erie ararow'e 14
Deseemmion ot thes Experitient. 2... 2o.0k a teatternne Gee ieeteeen sites 14
eESuLSTOLthen experiment: Hirst Inspection :.-saeecreia seise anes eal 16
SECO MG MMIS DEC ELOM a icts cys aes kas nls clske oddlaus) ladenes 21S cera ae aan epee Paces 17
Data concerning first two Inspections tabulated and compared....... 19
SIT PMMNEIS PEC TION: » ob. 5! Sais ie ofa a ona: Js ig tered tty ee Te ee re coe 19
Bourth inspection:..6:..5./.. Baap ov Wiasdls iets Sera RO ge hel rae 19
Greet alae IRESTIE 7 Sa ccs-2h dos Lone teen a eee ee ee Mie oe aks 21
Sampaio ot wimested. Mields). i... 5s). a/c > ue, +=,45.2 Mise seme ee eerste ele 21
Wotemrxpeniments, MeCESSATY. 2s .s.) csaeeu mies Seocee Wee eee eeioe ae 22
Pee PEG t iota WittOr WEST. aks «clic nieve srahn ohare maiare: See eotal ele talatereta Rey?
eneLaeRLOPtamnOLy ETE VEMtL OM. 1. +c + sceyeuvele a. spstaonse torent tteete o etetars loveretone starrer 24
Habits and Behavior of the Corn-Field Ant, Lasius niger americanus........ 27
Mee HRCI SMT MSE LTE = ESES Cyc bg oo /4 bg ae sled d la sb ucia Gabo s ements ale etebonervere meta 27
Beginning of a New Colony.........:.......: Foes fore mero Oona Manton Page at 28
SERENE tans Seis eis 2s - oso nels, ds'wnllecalececeaca tau oyeke eueee eee tatom ane enone ate 36
MpPPER EH EHEHEA hy ELOSERLILIOS ¢. 5 vidi 's, eral s 4 sia'e te o/2!ass ave eyeceberaterelenaree faucaa eteraloe claveleier el atwiee 31
Preamoccwnscds py aycing le Colony x... sic): sre «fe sul ine ohlen & elas ele B 33
memtiings Lovothen species, Of VANES... .0.' Wee. livres alas ecaies oe ate acetate siete leet 34
Beaihenrtor, Anvdathal Ado. wl NIG PAE eer ee MER ec eaatins con canta cohorenan ome o ee 34
Midamtation of Behavior to Changing Conditions... 2222.0... 5..ceceeeees 36
PeMMUCTRUELOR COLIN ON WATILS So. eg ok 2 oe Soe a odo ey ae ne a pele ate ewe ee 37
ere aia hanzer Of Crop soi. op os a.0.aio.8a vies. 2 cheyeletestatouste Sew anialers sighs ele 38
Mame airests G7 Clover Gnd. ALPAl fd... «<< 0x aise avine alta claeeee euaee 41
Enters OCU EL Ora Nene oc clreve otic Stes 24 acascnte w Aidt ane Slate sven Oionatadenaretaee Stara. reba ie eles weuc eee 41
naruto e torent Dy SLiSeCtss. 21s -..c'-/.75\> «.ala's sta +, «<a! atele, elatane ia hel ataleialene 2 stokes 41
EMME Os Che. SECM) CLOP i's :c5 i cnc oc: ea so e's wccjote'a ateeialeisia save etcte orate a erates 43
WoreLOlmo ts ASLO Vier LMSeCES sa seAuiee ora sie: «.sheisue Sialntel y aloha lohetetetemeasvoters ish Stet ctetensterokerer ene 45
Clover Seed-midge, Dasyneura leguminicola Lint. ........... 00.00 ee ee cence 46
Clover Seed-chalcid, Bruchophagus funebris How. ..............--.--+---- 53
Clover Seed-caterpillar, Enarmonia interstinctana Clem. ............e000+: 61
Pea-louse, or Clover-louse, Macrosiphum pisi Kalt.............00.cceeeee 66
Glover Leaf-weevil, Phytonomus punctatus Fab. 2.0.0... 0.0 cece ec cnee 83
Glover #*Root-borer,, Hylastinus obscurus, Marsh. 2.2% issn cen soe ce oo 92
Siover tHay-womn, Liypsopygia costalis Papi. on. oss e ace ce oti aceiciee ss «ale 96
Glover iaeat-midge, Dasyneura trifolt LOW... 60.006 ce cae dane tees essere 99
Clover Callipterus, Callipterus trifoli Momnell..................0eeseeeens 103
Glovers scem-borer, Languria mozard: -Latr. .0i.\.. docs eae tesserae ae 106
Mere sitones, suones Aavescens AM. sxe ooo ake es decile tale! Dia| ata shale since 112
Other Species of Sitones as Possible Clover Pests.........-...-..-..+--- 116
Clover-Root Mealy Bug, Pseudococcus trifolti Forbes..............-++-+- 117
Mette a Gerietal WATTIClGS Yc. oe ciacis She ecceeaa ala oaciete oa ante, oe ae oes 124

OS DECI Sc: s Fok o hoe ee mei ee IS de) e cian ae alee Ad slats aialeraars? aa 124

INTRODUCTION

With the passage, by the Forty-fifth and Forty-sixth General
Assemblies, of laws enlarging the scope of the work of the State Ento-
mologist’s office and greatly increasing its resources, it has become
desirable and possible for assistants of the office to prepare, for its
regular reports, articles on special subjects assigned to them, or upon
which they have personally done an important amount of investigation
or experimental work. The present report is the first to be prepared
under the new conditions, and the principal article in it is by Dr. J. W.
Folsom, who has served during his vacations as a university instructor
in entomology as a temporary assistant to the State Entomologist.

Consistently with the present method of publication of papers pre-
pared by the Entomologist and his assistants, the three articles of this
report have been previously issued as Bulletins 130, 131, and 134 of
the Agricultural Experiment Station of the University of Illinois;
Bulletins 130 and 131 in December, 1908, and 134 in April, 1909.

The following are the state laws recently passed respecting the
work of the Illinois Entomologist :

An Act to provide for the office of the State Entomologist, to
define its dutics, and to extend its equipment.

SecTION 1. Be it enacted by the People of the State of Illinois,
represented in the General Assembly: That it shall be the duty of
the State Entomologist to investigate, by himself or by his assistants,
all insects dangerous or injurious in this State to agricultural
and horticultural plants and crops, to live stock, to nursery trees
and plants, to the products of the truck farm and the vegetable garden,
to the shade trees and other ornamental vegetation of cities and towns,
to the products of mills and the contents of warehouses, and to all
other valuable property, and to investigate all insects in this State
injurious or dangerous to the public health; and he shall conduct ex-
periments with methods for the prevention, arrest, abatement and
control of injuries to person and property by such insects, giving no
preference in his investigations to one part of the State over another.
He shall, further, instruct the people of the State, by lecture and dem-
onstration, as may in his judgment be practicable and necessary, in
the best methods of preserving and protecting their property and their
health against injuries by insects; and he shall prepare, from time to
time, articles on the injurious and beneficial insects of Illinois, con-
taining the results of his researches, which articles shall be published
as bulletins of the Agricultural Experiment Station, and shall also be
issued biennially in an edition of one thousand copies as his official
report. He shall present to the Governor biennially an executive re-
port describing the operations and publications of his office, together
with a financial statement in detail.

Vv

vi

§ 2. To carry out the provisions of this Act there is hereby appro-
priated the sum of twenty-five thousand dollars ($25,000.00) [*| per
annum: Provided, that five thousand dollars ($5,000.00) per annum,
or so much thereof as may be necessary, shall be set aside for expenses
incurred by the State Entomologist under the “Act to prevent the in-
troduction and spread in Illinois of the San Jose scale and other dan-
gerous insects and contagious diseases of fruits:” And, provided,
further, that the work outlined in this section shall be carried out on
lines agreed upon by the State Entomologist and an advisory commit-
tee to consist of the director of the Agricultural Experiment Station,
two members to be appointed by the Illinois Farmers’ Institute and
two members to be appointed by the Illinois State Horticultural
Society.

§ 3. The advisory committee herein named shall meet at such
times and places as may be designated by the State Entomologist, or
upon a request of a majority of the committee. They shall serve
without compensation, except for expenses, to be paid out of the ap-
propriation herein made.

* * * * * x

AN Act to prevent-the introduction and spread in Illinois of the
San Jose scale and other dangerous insects and contagious diseases of
fruits, and repealing a certain Act therein named.

Section 1. Be it enacted by the People of the State of Illinois,
represented in the General Assembly: That it shall be the duty of the
State Entomologist of Illinois to inspect, or cause to be inspected by
his duly appointed assistants, at least once each year between July 1
and September 15, all nurseries and nursery premises in the State of
Illinois, as to whether they are infested by dangerous insects or in-
fected by dangerous plant diseases. If upon the inspection of any
nursery as above provided it shall appear that said nursery and its

premises are free from dangerous insects and dangerous plant dis-.

eases, it shall be the duty of the State Entomologist upon payment of
the expenses of inspection, and certified by him to give or to send to
the owner of said nursery, or to the person in charge of the same, not
later than October first, a certificate of inspection stating that said
iursery and premises are apparently free from such insects and dis-
eases, and such certificate shall be valid, unless revoked for cause as
hereinafter provided, for one year from the date of inspection, and no
longer. Z
The provisions of this section shall not apply to florists’ green-
house plants nor to flowers or cuttings commonly known as green-
house stock, and no certificate shall be required for the shipment of
native stock collected in the United States and not grown in nurseries.
If the State Entomologist shall find that part of a nursery is in-
fested with dangerous insects or infected by contagious plant diseases
and that the remainder of it is not so infested or infected, or if he shall
have reason to believe that a nursery is liable, by reason of its proxim-
ity to infested or infected premises, to become so infested or infected

*T wenty-one thousand dollars ($21,000) per annum appropriated for 1909 and 1910.

vii

before the next annual inspection, he may prescribe in writing such
measures of precaution, or may make in writing such conditions as to
the use of his certificate, as may in his judgment be necessary, and he
may withhold his certificate until such conditions have been accepted in
writing by the owner of said nursery; and the use of such certificate
without taking such measures of precaution or observing such condi-
tions shall subject the owner of said nursery to the penalties prescribed
in section 5 for a violation of this Act.

Whenever any nurseryman or seller of trees, shrubs, vines, plants,
buds, or cuttings commonly known as nursery stock, shall ship or de-
liver any such “stock he shall place and send on each car, box, bale,
bundle, package, or piece, a true copy of a valid certificate of inspec-
tion, signed by the State Entomologist of Illinois, or by another in-
spector duly approved by him, showing that the said stock has been
carefully inspected and found apparently free from any dangerous
insects or dangerous plant disease. Any person who shall deliver,
ship, or consign for shipment nursery stock without such certificate
attached, or who shall use such certificate in connection with nursery
stock any and every part of which has not been inspected and certi-
fied as aforesaid, or who shall alter or deface such certificate, or who
shall use an imperfect copy of such certificate, shall be liable to the
penalties prescribed in section.5 for a violation of this Act.

If the State Entomologist shall find that his certificate of inspec-
tion has been used in violation of law, he shall have power to revoke
and annul said certificate by written notice to the holder thereof, and
such notice shall take effect forthwith, and the use of said certificate
after it has been revoked and annulled, and before such revocation
has been withdrawn by the State Entomologist, shall subject the
holder of said certificate to the penalties provided in section 5 for a
violation of this Act.

It shall be the privilege of the nurseryman to ship, under the cer-
tificate issued to him, nursery stock grown for him elsewhere or pur-
chased by him from other states or countries: Provided, that all such
stock be received under a certificate satisfactory to the State Entomol-
ogist stating that it has been inspected where grown and found to be
apparently free from dangerous insects and dangerous plant diseases.
The State Entomologist shall send, once-each year not later than July
1, to all nurserymen in the State known to him, a list of official in+
spectors of other states and foreign countries whose inspection cer-
tificates may be accepted in this State, for one year from the Guts
thereof, as equivalent to his own certificate.

Every agent for a nursery outside of Illinois and eyery dealer: we
engaged in; growing trees, shrubs, plants, or vines, in this State, for
sale, who sells or delivers such stock in this State, shall, before -de;
livering the same, place on file in the office of the State Entomologist
a statement made under oath before an officer qualified to administer
oaths in the-locality where he may reside, or, if-a non-resident of the
State, in the locality where said stock is sold or delivered; that the
said stock has been duly inspected and was received by him accompas

Vill

nied with a valid official certificate of inspection or fumigation, a copy
of which certificate shall be filed by him with said statement for the
approval of the State Entomologist. Upon receipt of said statement
and copy of the certificate of inspection the Entomologist shall report
to the sender his approval or disapproval of said certificate. If dis-
approved he shall inspect, or cause to be inspected, the nursery stock
to which the said statement applies, and if he shall find said nursery
stock to be apparently free from dangerous insects and dangerous
plant diseases he shall give or send to the owner thereof, upon pay-
ment of the expenses of the inspection, a certificate to that effect, and
the delivery of such stock without an accompanying certificate of in-
spection issued by the State Entomologist or approved by him shall
subject the agent, dealer, or other person selling or delivering the same
to the penalties prescribed in section 5 for a violation of this Act.

§2. That all gardeners, horticulturists, nurserymen, superin-
tendents of public parks, and other growers of or dealers in plants of
any kind upon their own lands, upon leased lands or premises, or
upon public parks or highways shall free and keep freed all plants,
shrubs, trees, vines, cuttings, scions, buds, stocks or other plant parts
grown, cultivated, or dealt in by them, from all injurious insects and
fungus pests, which are liable to spread from the plants or premises
infested to other plants on the public htghways or upon lands belong-
ing to other owners, and all plants, shrubs, trees, or parts of such so
infested are hereby declared to be a nuisance to be abated as herein-
after prescribed ; and their maintenance, after notice as hereinafter set
forth, is hereby declared a misdemeanor punishable as provided in
section 5 of this Act. If the State Entomologist shall have reason to
suppose that any nursery, orchard, fruit plantation, or other property
or place in this State, is infested by dangerous insects or infected with
contagious plant disease, he shall have power to inspect or to cause to
be inspected, from time to time, such nursery, orchard, fruit planta-
tion, or other property, and for the purposes of such inspection he
and his assistants are authorized, during reasonable business hours, to
enter into or upon any farm, orchard, nursery, garden, storehouse, or
other building or place used for the growing, storage, packing or sale
of trees, plants or fruits; and if the State Entomologist shall find, by
inspection as aforesaid, that any person, firm, or corporation is main-
taining a nuisance as described in this section, he shall notify in writ-
ing the owner or occupant of the premises containing the nuisance so
disclosed of the fact that such nuisance exists. He shall include in
such notice a statement of the conditions constituting such nuisance,
an order that the same be abated within a specified time, and a direc-
{ion, written or printed, pointing out the methods which should be
taken to abate the same. Such notice or order may be served per-
sonally, or by depositing the same in the post office, properly stamped,
addressed to the owner or occupant of the land or premises upon
which such nuisance exists, and the direction for treatment may con-
sist of a printed circular, bulletin, or report of the State Entomologist
or of the Agricultural Experiment Station, or an extract from the

ix

same. If the person so notified shall refuse or fail to abate said nui-
sance in the manner and within the time prescribed in said notice, the
State Entomologist may cause such nuisance to be abated, and he
shall certify to the owner or person in charge of the premises the cost
of abatement, and if not paid to him within sixty days thereafter the
same may be recovered, together with the cost of action, before any
court in the State having competent jurisdiction. In case the notice
and order served as aforesaid shall direct that any growing plant,
shrub, or tree, shall be destroyed, and the owner or grower of such
plant, shrub, or tree, shall consider himself aggrieved by such order,
he shall have the privilege of appeal, within three days of the receipt
of the notice, to the county court of the county in which said property
is situated. The appeal shall be made in like manner as appeals are
taken to the county court from the judgments of justices of the peace,
Written notice of such appeal served by mail upon the State Ento-
mologist shall operate to stay all proceedings until the decision of the
county court, who may, after investigating the matter, reverse, mod-
ify, or confirm the order of the State Entomologist. Such decision
shall then become the order of the State Entomologist, who shall serve
the same as hereinbefore set forth, and shall fix a time within which
such decision must be carried out. Any person, firm, or corpora-
tion failing to obey an order of the State Entomologist, made and
served as prescribed in this section, within the period of time therein
specified, shall be deemed guilty of a misdemeanor and liable to pun-
ishment as prescribed in section 5 of this Act.

§ 3. Whenever any trees, shrubs, plants or vines are shipped
from place to place in this State, or shipped into this State from
another state, country or province, every car, box, bale, bundle, pack~-
age or piece thereof shall be plainly labeled on the outside with the
name of the consignor, the name of the consignee, and a certificate
signed by a state or government inspector showing that the contents
have been inspected by such inspector, or by his authority since the
first day of July last preceding, and that the trees, vines, shrubs, and
plants, there present and therein contained, appear free from all dan-
gerous insects and diseases. Whenever any trees, shrubs, vines, or
plants arrive in this State without such certificate plainly fixed on the
outside of the package, box or car containing the same, the facts must
be reported within twenty-four hours to the State Entomologist by the
railroad, express or steamboat company, or other person or persons
carrying the same, and it shall be unlawful to deliver any such prop-
erty until it has been inspected by the State Entomologist or his as-~
sistant and by him certified to be free from dangerous insects or con-
tagious diseases. Any person receiving nursery stock brought into
this State from outside this State, and not accompanied by a valid
certificate as above prescribed, shall at once notify the State Entomol-
ogist of that fact, and shall not allow such uncertified stock to leave
his possession until it has been inspected and released by the State
Entomologist or his assistant. Any agent of any railroad, steamboat
or express company or any other person or persons carrying such

x

property as aforesaid, or any consignee of such property, who shall
fail to give notice to the State Entomologist as above required shall
be deemed guilty of a violation of this Act, and subject to the penal-
ties prescribed in section 5.

§ 4. Any owner of an orchard or other fruit plantation in bear-
ing condition may apply to the State Entomologist for an inspection
of the same with reference to the presence of the San Jose scale or
other dangerous insects or plant diseases liable to prevent the sale or
lessen the value of his fruits, agreeing in his application to pay in full
the expenses of the inspection, and upon receipt of such application
and agreement, or as soon thereafter as may be conveniently prac-
ticable, the State Entomologist shall comply with such request, and
upon receipt of the expenses of the inspection he shall issue to the
applicant a certificate to the facts disclosed by the inspection.

§ 5. Any person who shall violate the provisions of this Act with
reference to the sale, shipment, delivery, receipt, or transportation of
nursery stock, or with reference to the use, alteration, or defacement
of a certificate of inspection relating to the same, or who shall remove,
without the written permission of the State Entomologist, infested or
infected property concerning whose condition he has received official
notice from the Entomologist, or who shall maintain a nuisance as
described in section 2 of this Act, after notice by the State Entomolo-
gist and direction for its abatement, or who shall offer any hindrance
or resistance to the carrying out of this Act, shall be adjudged guilty
of a misdemeanor, and upon conviction before a justice of the peace
shall be fined not less than twenty-five dollars and not more than one
hundred dollars for each and every offense, together with all costs of
the procedure, and shall stand committed until the same is paid. It
shall be the duty of the State Entomologist to furnish to the State’s
Attorney all information in his possession concerning violations of
this Act, and the State’s Attorney shall prosecute such violations of
this Act, and amounts so recovered shall be paid into the treasury of
tev State.

$6. The office of the State Entomologist shall be established at
the University of Hlinois, the trustees of which shall provide for him
and his assistants such office and laboratory rooms as may be neces-
sary to the performance of their duties. He shall have power to ap-
point a chief inspector and such assistants as may be necessary to the
execution of this Act, and to fix a reasonable compensation for their
labors, and their acts, done in pursuance of his instructions, shall have
the same validity as his own. He shall certify to the State Auditor
the amount of his expenses and the amount of the salaries and ex-
penses of the chief inspector and assistants employed under this Act,
and the Auditor shall thereupon draw his warrant upon the State
Treasurer for the amount, which shall be paid out of the funds pro-
vided for carrying this Act into effect. The State Entomologist shall
make to the Governor a biennial report of his operations under this
Act, together with a financial statement in detail, and he shall also
make each year to the State Horticultural Society, at its annual meet-

xi

ing, a statement showing the Illinois nurseries inspected, the number
and kinds of certificates issued, the location and ownership of the
premises treated or disinfected by him or his assistants, and the kinds
and amounts of property destroyed by him in pursuance of this Act.
§7. An Act entitled, “An Act to prevent the introduction and
spread in Illinois of the San Jose scale and other dangerous insects
and contagious diseases of fruits,’ approved and in force April 11,
1899, is hereby repealed.

STEPHEN A. ForBEs,
Tilinois State Entomologist.
Urbana, August 13, 1909.

EXPERIMENTS WITH REPELLENTS AGAINST
THES CORN] ROOT-APEHIS,
1905 AND 1906

The corn root-aphis, a minute, bluish green, sluggish, soft-bodied
insect found on the roots of corn, is one of the most destructive and
dangerous insect pests of the corn plant. Beginning as soon as the
kernel sprouts to suck the sap from the young roots, it may continue
its injury without interruption until frost, unless the infested plant
in the meantime perishes. It has an enormous power of multiplication,
producing, under favorable circumstances, as many as sixteen genera-
tions in a season, and it is capable of spreading from field to field
rapidly on the wing, many of each generation, except the first of the
year, having the power of flight.

Altho a peculiarly sluggish and stupid insect, wholly unable to
make its own way unaided, it has always in its service one of the most
capable, abundant, active, and persistent of our common insect species.
This is the so-called corn-field ant (Lasius alienus americanus), in
whose charge the corn root-aphis is usually found, and by which its
eggs, laid in fall, are carried thru the winter. This corn-field ant
has no power of injuring the corn directly, except as it may occasion-
ally, er under peculiar circumstances, devour the softened kernel in
the earth, and the root-aphis, left to itself, can not even get access to its
food in numbers to do any noticeable harm; but the two in partnership
check the growth of the plants, and even kill outright whole fields of
‘corn, the aphis making the destructive attack, and the ant protecting,
transporting, and guarding the aphis, and collecting, preserving, and
hatching its eggs.

The practical control of this pair of insects is especially important
because the injury done to corn, already very heavy, is sure to increase
with time. The more generally and continuously corn is grown, and
the more the soil deteriorates under continuous cropping, the greater
this aphis injury must become. It is hence most serious and threaten-
ing in those very parts of our area best adapted to corn, and is much the
greatest now in Illinois in the central part of the state, where corn is
the principal crop.

Neither of these insects is subject, so far as known, to destruction ~
by parasites or by contagious diseases, the principal natural checks on
the multiplication of most other injurious species. About the only
natural agency which can be depended on to reduce the numbers of
the corn root-aphis is a long-continued soaking of the ground by fre-
quent heavy rains, especially if these come in a slow, cool spring. The
very wet spring of 1907, for example, seems to have had the effect to

2

drown out the root-lice and also, to some extent, the maggotlike young
of the ants under ground; and some fields heavily enough infested in
April and early May of that year to make a profitable crop very un-
likely, were completely cleared of root-lice by the beginning of June,
and contained unusually few ants.

Our later work on the ant-aphis problem has been done mainly on
two lines. We have attempted to test, by field experiments, the value
of a repeated deep and thoro stirring of the soil previous to planting,
and we have experimented with offensive applications to the seed, of a
kind to last a considerable time in the ground, and to keep the ants,
and consequently the aphids, out of the hills as long as possible while
the plant was still young and especially sensitive to injury. Experi-
ments of the first class were reported in Bulletin 104 of the Agricul-
tural Experiment Station published in October, 1905, and again in the
Tweuty-fourth Report of the State Entomologist, pages 8 to 29; but
those with repellents applied to the seed in 1905-06 are here fully re-
ported for the first time.

REPELLENT APPLICATIONS TO THE SEED

My attention was first called to the fact that applications to the
seed might serve to protect young corn against root-louse attack by
statements occasionally made by farmers who had treated their seed-
corn with kerosene or turpentine just before planting.* Having, I
must confess, very little faith in this treatment, I nevertheless directed
an assistant, Mr. E. O. G. Kelly, in charge of my field work in 1905,
to test the effect of kerosene used in this way, and as part of a general
field experiment for the protection of corn against aphis injury, he
planted a small plot in an experimental field with seed which had been
soaked in kerosene for half an hour.

The effect of this treatment was a double surprise to us. In the
first place, only about half as much of the corn grew as in other ex-_
periments made in the same field with seed from the same lot, serving,
consequently, as checks on this; the other half swelled up with the
moisture absorbed, but never sprouted. Furthermore, germination
was delayed, growth of the young corn was slow at first, and many of
the plants were dwarfed and crippled, the growing tip or plumule of
the plant making its way with great difficulty out of the inclosing
sheath (the coleophyl) which protects it as it grows upward thru
the earth. In the second place, altho the field of corn of which this
planting was a part was heavily infested and noticeably injured by the
corn root-aphis, this special plot, when examined some weeks after
planting, was found to be almost wholly free from the aphis, and to
contain but few ants; and at husking time its yield equaled in quan-
tity and excelled in quality that of like areas in other parts of the same
field. The treatment of the seed had evidently so repelled the ants

*See especially miy address on the corn root-aphis in the Tenth Report of the Illinois
l‘armers’ Institute, p. 49.

3

and aphids that protection from their injury had more than compen-
sated for the original poor stand. It thus became our problem so to
modify this treatment as to get the beneficial result without risk of
the injury.

It was evident enough that kerosene merely applied to the seed
could act only by reason of its persistent odor—peculiarly offensive to
ants—and it seemed quite probable that corn might be so treated with
this or some other strong-smelling substance that ants would be kept
out of the hills for a considerable time and that the seed would not be
injured. As a test of substances possibly useful for this purpose, a
long series of experimental plantings was made, from June to August,
1905, and from February to July, 1906, in the field, at Urbana, and in
the insectary connected with my office there, and a careful record was
kept of the percentage of kernels germinating in each planting, and of
the condition of the corn plants for several days after they appeared
above ground. The substances thus tested as to their effects on corn
were kerosene, kerosene emulsion, crude petroleum, turpentine, car-
bolic acid, formalin, oil of lemon, oil of wintergreen, oil of cloves, oil
of sassafras, wood alcohol, common alcohol, coal-tar. coal-tar water,
carbon bisulphid, chlorid of lime, kainit, flowers of sulphur, lime, salt,
various compound solutions of sulphur, lime, and salt, and of sulphur,
lime, and blue vitriol, copper sulphate, iron sulphate, mustard, cam-
phor, musk, lysol, tobacco-water, the proprietary insecticides known
as “‘Scalecide,” “Con Sol,” “Calcothion,’ and “Fruitolin,’ and the so-
called “Rex Dip.”

Prior EXPERIMENTS, 1905

For this purpose the use of a plot of ground was obtained in June,
1905, on the farm of the Experiment Station at Urbana, on which the
corn was planted in rows by hand, usually two grains to the hill.
Fifteen thousand five hundred kernels were planted in this plot, 5750
of them after treatment with kerosene, 2050 with kerosene emulsion,
2000 with tar-water, 3650 with turpentine, and 2050, with no special
application, serving as checks. The principal plantings were those
made June 15, of 1500 kernels, and June 28, of 12,500 kernels.
Smaller additional plantings, varying from 50 to 1000 kernels, were
made June 29 and 30. July 18 and 21, and August 9.

The results of the planting of June 15 were determined by an in-
spection June 26, and those of June 28 were determined July 20—the
first, eleven days after planting and the second after twenty-two days.
The weather of these two intervals differed materially, that between
June 15 and June 26 being rather dry, and that between June 28 and
July 20 decidedly wet—a fact to be borne in mind at some points in
comparing the two series of experiments. The ground must have been
fairly moist, however, June 15, since a rain of 1.05 inches had fallen
on the 10th, but the only rain to fall during the eleven days following
June 15 was .06 of an inch on the 20th. Between the 28th of June
and the 20th of July, on the other hand, rain fell on sixteen days, to

4

the total amount of 5.34 inches—that of one day, July 5, amounting
to 1.44 inches.

Treatment of seed with kerosene.—The seed-corn experiment with
kerosene was so varied as to bring into comparison the results of sim-
ply dipping the seed and planting immediately afterwards, and of
soaking it for 5 minutes, 10 minutes, 20 minutes, and 30 minutes, and
for 11 days, 20 days, and 41 days. Tests were likewise made of the
effect of first soaking the seed in water before putting it into kerosene.

The checks to these experiments—2050 kernels which were planted
in ten lots of 50 to 500 kernels each at several dates between June 15
and July 21—germinated in ratios ranging from 83 to 96 percent, with
an average of 89; and with this average, of course, the germination
ratios of the various experiments are to be compared.

Eight experimental lots, containing 2225 kernels in all, received
the simplest treatment—a mere dipping in kerosene immediately before
planting. The ratios of germination for seven of these lots varied
from 84 to 97, with an average of 91. The eighth lot, of only 50 ker-
nels planted in earth kept continuously moist, gave a germination ratio
of 62 percent, and including this the average for the series is 87.6.
It may fairly be said, consequently, that injury by this treatment was
practically imperceptible, but that a suspicion is created of possible
damage to the seed if the weather is continuously wet after planting.

Eight lots of seed, numbering 2225 kernels in all, were soaked in
kerosene for 5 minutes just before planting. Here also no perceptible
damage was done to the seed, the germination ratio amounting to 88 8,
to be compared with 89 for the checks.

Of eleven additional lots, averaging 100 kernels each, soaked in
kerosene for periods varying from 10 to 30 minutes, 85.2 percent grew,
the ratios ranging from 78 to 96. We begin to see here evidences of
slight but obvious injury to the seed as a consequence of the treatment.
It is nevertheless puzzling to find that 89 kernels grew out of 100 ker-
nels soaked for 11 days, and that 86 percent of 50 kernels soaked for
20 days and 80 percent of the same number soaked for 41 days, also
grew.

In many of these kerosene experiments, even tho the kernels
sprouted eventually and plants appeared above ground, the germina-
tion was much retarded and the plants were more or less distorted and
deformed—an effect returned to on a later page of this article.

Kerosene emulsion.—For some obscure reason the result of the
treatment of 400 kernels with kerosene emulsion June 15, was very
much less favorable than that of 1500 kernels planted June 28. In
the first experiments the seed was soaked for 30 minutes in emulsion
diluted to contain 10 per cent, 20 percent, 40 percent, and 50 percent
of kerosene, with the effect to give a germination ratio, eleven days
after planting, of 46 percent for the first, 76 for the second, 63 for the
third, and 57 for the fourth of these lots, or an average of 60.5 percent
to grow from these plantings. June 28, emulsions were used contain-
ing 10, 20, and 40 percent of kerosene, in which corn was soaked for
30 minutes, each of three lots containing 500 kernels. The percent-

ages to grow varied from 91.6 to 95.8, with an average of 93. I am
unable to explain these discrepancies, and consequently can not attach
any especial importance to these experiments with kerosene emulsion.

Turpentine.—A like discrepancy appears in the turpentine experi-
ments, four plantings for which were made June 15, and six plantings
June 28. The first, of 100 kernels each, averaged 561% percent to grow.
and the second, of 500 kernels each, averaged 88 percent. In the plant-
ings of 100 kernels made June 15 immediately after dipping in turpen-
tine, 28 percent grew; while of another hundred soaked in turpentine
for 5 minutes, 76 percent grew. Of a third lot, soaked for 10 minutes,
95 percent grew; and of the last lot, soaked for 30 minutes, but 27
percent grew. These variations are so unaccountable and confusing
as to vitiate this experiment.

On the other hand, the results of the six plantings of June 28
varied only from 85 to 90 percent, and these results may be fairly
accepted. Of 500 kernels dipped in turpentine and planted at once,
90 percent grew; of those soaked for 5 minutes before planting, 88
percent grew; and of those soaked for 20 minutes, 90 percent grew.
Of another lot of 500 kernels, soaked first in water for 10 minutes and
then merely dipped in turpentine, 90 percent grew; of a second lot
treated in the same manner except that they were soaked for 5 minutes
in turpentine, 85 percent grew; and the same ratio was obtained from
a third lot similarly treated except that the kernels were soaked for
20 minutes in water. This treatment with turpentine may be said,
on the whole, to have been apparently without injurious effect, since
the check plantings of this date gave a germination average of 89 per-
cent, while the later plantings with turpentine averaged 88 percent
to grow.

Tar-water.—lwo thousand kernels were planted June 28, after
treatment with coal-tar water obtained from the bottom of a gas tank,
or from the top of a tank of coal-tar, at the gas works. One thousand
of these kernels, merely dipped in the tar-water, gave a germination
ratio of 94 percent, and of another thousand soaked in it for 5 minutes,
88 percent grew.

The principal data of the foregoing discussion are summarized in
the following table.

Prot EXPERIMENTS WITH REPELLENTS, 1905

No Treatment of Seed. Check Plots

Date | Treatment | No. of kernels Percent to grow
June 15 | Mone oot Sees Ane leang | 200 | 88
estas) emieeher a anticats MccsNe eens suet 1500 89
BE Aa cts Ee a Patee ee suk Leak ross 9 0 200 83
MOM Ri ogc gatas Scan, «+ 150 95
(Geineredill GhSUAI(S @uMel \ete) less arg Bares eee Oo, eis Hie 89

6

Seed treated with Pure Kerosene

|
Date Time in kerosene No. of kernels Percent to grow
june 15! “iGDipped wrists keen ale erste 100 95
eee Pree hee ae err rem rictp bate 1000 97
pfho ie) OUR LES Ry secs ame ere 100 88
ia DO a tao a Sore alstece tele 1000 94
28 es ss Wet:i) ctine on tse 1000 91
ae ls 10 a DEY ies ke cere 100 85
ate! 20 rE ss Visit staioteers s | 100 87
als 30 be gether ator 100 82
128 30 “3 Wetiincrncsicercct | 500 81
are) MDS days veto virtare nk alohotere Brolcanite 100 89
fatly ASe | (20 vos 6 eee area | 50 86
ATS OS ala arty ee ee Waa ear | 50 80
General average of kerosene treatments................- 88
Seed treated with Kerosene Emulsion
a5)
Date ees | Time inemulsion) No. of kernels Percent to grow
erosene |
June 15 10, = 3130 minutes... al) oe aimee 46
ene. | 20 AO" ye Rereat ent | 100 | 76
ees 40 ISO trae vie ae pee 100 63
eS 50 Sia 100 57 60.5
ees 10 SO Vere caekicroeee 500 | 92
ees 20 SO eee 500 | 92
eel 40 eh) Rae ecommerce 500 aoe 96 93%
Seed treated with Turpentine
Date Time in turpentine No. of kernels Percent to grow
June 15 Dippedixrs acute pevr trate slemiele oa 100 28
soy Or ol) PO MUNMES: air) e eye scree: 100 76
PALO Artie O ee naw miter act teithae rts eae eee | 100 95
EPR ME ROO! rc t ee oldie tl stems ais lecceyetere 100 2756.5
a8 Dipped: Lycee eee 500 90
Say Ao Yea os Welisiccrd acho cers 500 90
‘a 2S SMMIMUteS. ey meee cis cic 500 88
28 ke WOE tetris 500 85
ESF eite BO ne 40s Diyas vee 500 , 90
Ses. 20 3 Wiet easter 500 DEVS aco
Seed treated with Coal-tar Water
Date Time in tar-water | No. of kernels Percent to grow
2 ees 2 _ =| Ben : :
Jute 2B. tl Dipped. .s ceca saeleaees | 1000 | 94
Ie | <S-main tes: thee eee Moiese ees 1000 88

7

Pot EXPERIMENTS, 1906

In all the experiments of 1906, Leaming seed-corn of excellent
quality was planted, at a depth of an inch, in good black soil contained
in ordinary earthen flower-pots seven inches across, and kept in the
insectary of my office building at Urbana. Temperature and moisture
conditions, being under strict control, were made as nearly those of
a normal spring as possible. Thirty-five check lots of 50 kernels each
(1750 kernels in all) were planted with untreated seed in the course of
these experiments. Sixteen hundred and eighty of these kernels ger-
minated, and this germination ratio (96 percent) may be used for com-
parison in determining the effect of our various applications to the
seed.

Kerosene.—Kerosene was used in two ways in these experiments:
(1) by mixing it thoroly with the seed in quantities varying from %
of a fluid ounce to 3% ounces for each gallon of corn; and (2) by
putting the seed into kerosene and soaking it there, previous to plant-
ing, for periods varying from 10 minutes to 19 hours. The main
results of these various experiments were as follows:

Of 800 kernels planted after stirring in kerosene thoroly, at rates
varying from ¥% of an ounce to 2 ounces for each gallon of corn, 98
percent germinated, and only 2 of the plants showed any trace of
injury. Fifty kernels of this lot, treated at the rate of 2 ounces of
kerosene to the gallon, all sprouted, and none of these plants were in-
jured. Furthermore, of 200 kernels treated with kerosene at the rate
of 24% to 3% ounces to the gallon of corn, 92 percent germinated,
and only 3 plants gave any appearance of injury. It would naturally
be inferred from this experiment that at least an ounce (two table-
spoonfuls) of kerosene to the gallon of corn might be safely used
under conditions as favorable as those in our management, but we
shall later find evidence, in the outcome of a field experiment made
the following spring, that only half this amount injured corn slightly,
but still appreciably, under the weather conditions of 1906.

Soaking the corn in kerosene for 10- to 20- minute periods, 200
kernels in each experiment, gave a germination ratio of 88 percent for
the first and 93 percent for the second, but with the appearance of
injury to 77 percent of the plants in the 10-minute lot and of 80 per-
cent in the 20-minute lot. Furthermore, the plants which grew, aver-
aged only 234 inches high fifteen days after planting, while 100 plants
from untreated seed averaged 61% inches. The corn would perhaps
have outgrown this backset, and might have made a crop, if planted
out-of-doors, better than the average in the field, provided that the
latter was injuriously infested by the corn root-aphis.

Soaking seed in kerosene for periods varying from 4 hours to 19
hours gave variable results, as reported by Mr. Kelly. Only 1 out
of 50 grains (2 percent) soaked for 4 hours lad sprouted at the end
of thirteen days, while 164 kernels out of 200 (82 percent) which had
been soaked for 16 hours before planting, appeared above ground

8

within six days, 92 percent of the plants finally showing more or less
injury. On the other hand, but 3 out of 100 kernels soaked for 19
hours in kerosene were in condition to grow, and all the plants from
these 3 were injured.

Perplexing discrepancies of this sort were of rather frequent oc-
currence in these experiments, and showed that one must apply the
results with caution, keeping well within the limits of variation. In
view of the observed effect of an-overdose of kerosene on the young
plant, as described in. the earlier part of this article, it is important
to note that no dwarfing or distortion of the corn plants was seen
in any of these experiments.

Crude Petroleum.—A series of tests made with 600 kernels of
corn by soaking them in crude petroleum for various periods ranging
{from 5 minutes to 74 hours, gave us reason to believe that this sub-
stance was too dangerous to be used in this way. No experiments
were made, however, with the mere mixture of minimum quantities
of petroleum with a gallon of corn. The same variable and discrepant
results were reported here as in the experiments with kerosene, 14
kernels growing out of 50, for example, which had been soaked for
30 minutes, and 46 out of 50 which had been soaked for 19 hours.
After 5 minutes’ soaking, only 42 kernels grew out of 50 planted, and
8 of the plants which appeared were injured.

Oil of Lemon.—A good quality of oil of lemon,* as obtained at a
local wholesale drug-store, was used in solution with ordinary alcohol
at strengths of 1 part in 10 or 1 part in 3 of the oil to the alcohol. The
seed was soaked in these mixtures for periods varying from 5 minutes
toan hour. Two plantings were made with kernels treated by stirring
3 ounces of the 10 percent solution thoroly into a gallon of the seed.
Of 450 kernels treated in the various ways described, 95 percent ger-
minated with virtually no injury to the plants.

The only damage done to the seed in experiments with this mixture
of lemon oil and alcohol appeared in two lots of 50 kernels each
soaked in the 10 percent solution, one of them for 20 minutes and
the other for 19 hours. In the first of these lots 16 kernels, and in
the second lot 21 kernels, failed to grow. It was a perplexing fact
that serious injury to the seed was thus reported by Mr. Kelly to
have followed the use of a 10 percent solution for 20 minutes, while
no harm resulted from a 10 percent solution applied for 30 minutes
or for an hour, or from a 33 percent solution applied for 20 minutes
or for 30 minutes. It appeared safe to conclude, however, that a 10
percent solution used merely to moisten the seed, say, at the rate of
3 ounces to the gallon of corn, might be applied without risk of injury
to the seed; and our field experiments were made, later in the season,
on this basis.

Other vegetable oils —Oil of wintergreen, oil of cloves, and oil
of sassafras were tested, each with 400 kernels, divided into eight

*The brand and manufacturer of this sample could not be learned later, when it became
important to know just how the results of these experiments were obtained.

~

9

experiments. All proved to be too frequently injurious to the seed
to make it safe to trust to them—the oil of cloves the most injurious
and the oil of wintergreen the least so. Solutions of less than 10
percent strength were not used, however, and no trial was made of
any milder form of application than soaking the seed for 5 minutes in
an alcoholic solution of the oil. It is possible, consequently, that a sim-
ple stirring into the seed of minimum quantities of a 5 or 10 percent
solution, as in the case of the oil of lemon, might have been harm-
less—excepting, however, the oil of cloves, which killed from 44 to
100 percent of the kernels in each experiment.

Carbolic Acid.—The action of carbolic acid was tested by soaking
seed-corn from 5 to 30 minutes in solutions of the commercial acid
in water, varying in strength from 2 to 30 percent. No injury was
done by either 2 or 5 percent solutions applied to lots of 200 kernels
each for 5, 10, 20, or 30 minutes, but the 10 and 30 percent solutions
killed virtually all the seed even when applied for only 5 minutes. In
our subsequent field experiments a 3 percent solution only was used,
and then at the rate of 3 ounces of the solution to a gallon of corn.

Formalin.—A few experiments made with formaldehyde, in water
solutions of 4 percent, 25 percent, and 50 percent, showed that at 4
percent this substance was harmless to seed-corn soaked in it for
any period between 5 minutes and half an hour. Two hundred ker-
nels thus treated gave a germination ratio of 94 percent. The plants
which grew, on the other hand, averaged only 4% inches at a time
when the single check of 50 plants averaged 6 inches. The higher
strengths mentioned were both extremely injurious, the 25 percent
mixture killing from one fourth to four fifths of the seed, according
to the period of use, and the 50 percent mixture, applied for half an
hour, killing it all.

The Alcohols——To distinguish between the effects of alcohol and
oils in some of the above mixtures, 200 kernels were soaked in com-
mon alcohol for periods ranging from 5 minutes to half an hour,
and 200 more in wood alcohol from 5 minutes to an hour, with the
result that no injury was done except by the longer periods of treat-
ment. From 98 to 100 percent of the grains grew after soaking 10
or 20 minutes in ordinary alcohol, but only 66 percent after 30 minutes’
treatment ; and 95 percent grew after 5 or 10 minutes in wood alcohol,
but only 74 percent after 20 minutes and 14 percent after an hour.
From this it may be inferred that seed-corn is uninjured by as much
as 10 minutes’ soaking in either kind of alcohol, but that more than
this is dangerous, and that injury will begin to appear after 20 or 30
minutes’ treatment—sooner if the solvent is wood alcohol.

Lysol—tThis highly odoriferous coal-tar product was applied to
seed-corn in twenty-one lots of 50 kernels each, and in aqueous solu-
tions of 1 percent, 2 percent, 5 percent, and 10 percent, the corn
being soaked in each of these 5 minutes, 10 minutes, 20 minutes, and
1 and 2 hours. Another lot of corn was soaked for 5 minutes in pure
lysol, and lysol was applied to seed-corn at the rate of half an ounce

10

of the fluid to the gallon of corn, and at the rate of an ounce to the
gallon. No injury was done by the 1 percent solution applied in
periods up to two hours, and the 2 percent solution was harmless up
to 20 minutes. Two hours’ soaking at the latter strength was in-
jurious, giving a germination ratio of but 68 percent, and all the
plants growing were more or less injured. The 5 percent solution
did no harm when used for 5 or 10 minutes, but after 20 minutes’
treatment only 78 percent of the kernels grew, while after 2 hours’
treatment at this strength all the corn was dead. Even 5 minutes’ use
of a 10 percent solution proved injurious. Corn treated with the
pure lysol at the rate of half an ounce to a gallon of the corn was
uninjured, 92 out of 100 kernels of it germinating; but when this
strength was doubled, the germination ratio fell to 73 percent. From
these experiments we may infer that a 2 percent solution of lysol in
water may be used to soak the seed if treatment be not continued
over 10 minutes, and that half an ounce of the undiluted lysol may
be stirred into a gallon of corn without risk of injury.

Kaimt.—The potash fertilizer known as kainit, which has some-
times been recommended as a repellent to the corn root-aphis, was
tested on 300 kernels divided into six lots. The total germination
ratio was 90 percent. One lot, in which the planted seed was thickly
covered with kainit, fell to 78 percent.

Lime, Sulphur, and Salt.—Saturated solutions of either lime or
salt were harmless to seed-corn soaked in them for 30 minutes or
less, and 84 percent of the kernels germinated when planted after
rolling in a plaster of wet salt, none of the plants showing injury.
Simple powdered sulphur, 1 or 2 pounds to the bushel of corn, had
no effect upon the seed, however it was applied; neither did mixtures
of lime, sulphur, and salt, or lime, sulphur, and blue vitriol, unless
these were applied for more than an hour. After 2 hours’ soaking
in a solution of lime and sulphur (15 pounds of each to 50 gallons
of water), seed-corn sprouted in a ratio of 80 percent, with an ap-
pearance of injury to all the plants which grew. A ready-prepared
solution of sulphur sold under the name of “Rex Dip” was variously
used in the treatment of seed-corn, and in every case without notice-
able effect on the germination of the seed until this had been soaked
in it for more than an hour. Seven hundred kernels divided into four-
teen lots of 50 each and soaked for periods varying from 5 minutes to
an hour gave a general germination average of 96 percent, 4 percent
more than the normal for untreated corn of this sample. Two hun-
dred kernels planted in four lots of 50 each, and soaked for 2 hours,
gave a ratio of 88 percent of kernels germinating.

Chlorid of Lime—Used in a saturated solution, or applied by
rolling the kernels in a wet plaster, chlorid of lime was without effect
on the sprouting of the seed or the growth of the plants. Two hun-
dred kernels soaked for 5 to 30 minutes in the solution grew in a
ratio of 98 percent, and 100 kernels rolled in a thin paste of the wet
lime all grew. Dry chlorid mixed with the seed was also harmless
to 50 kernels.

‘
le

11

Carbon Bisulphid.—A carbon bisulphid treatment was also harm-
less so far as tested by stirring the undiluted fluid into the corn at
the rate of 2 and 4 ounces per gallon, or by soaking the seed in the
fluid for 10 minutes.

Copper Sulphate —Seed-corn soaked in a saturated solution of blue
vitriol was uninjured after 5 and 10 minutes’ treatment, and 90 per-
cent of the seed germinated after 20 minutes’ soaking, but only 83
percent after 30 minutes (16 percent of the plants being injured) and
80 percent after an hour, all of these last plants showing injury.

Iron Sulphate—Two hundred kernels of seed-corn soaked in a
saturated solution of copperas for periods varying from 5 minutes
to 16 hours, and in lots of 50 kernels each, were uninjured as to
germination, averaging 95 percent.

Tobacco-water.—Strong solutions of tobacco-water, obtained by
boiling the stems, did no injury to seed or plant, even when the corn
was soaked from 1 to 24 hours. Three hundred and fifty kernels thus
treated, 100 of them for the longer period, gave an average germina-
tion ratio of 98 percent.

Musk.—Commercial Tonquin musk, mixed with wood alcohol at
the rate of 1 part of musk to 10 of the solvent, did no injury to the
seed when 3 ounces of the mixture were thoroly stirred into a gallon
of corn. Neither a 5 percent nor a 10 percent solution of the musk
in ordinary alcohol injured the seed after 5 minutes’ soaking, but a
longer exposure diminished the ratio of germination, and soaking for
an hour was decidedly injurious. These effects were, however, quite
possibly due to the alcohol.

Mustard.—Mustard was injurious when applied in the powdered
form, but 16 hours’ soaking in a saturated solution with water did
not affect germination.

Miscellaneous substances—The proprietary insécticides ‘Scale-
cide,” “Con Sol,” ‘“Calcothion,” and “Frutolin” were all without effect
upon the seed, tested by soaking the seed in them for 5 to 30 minutes.
“Scalecide’”’ was used in 5 and 10 percent mixtures with water, “Con
Sol” in a 2% percent mixture, and “Calcothion” and “Frutolin’” pure.
Twenty lots, amounting to 1000 kernels, were soaked in these various
insecticides, none giving less than a germination ratio of 92 percent,
and most of them rising to 98 and 100 percent.

Fifty kernels of corn left in coal-tar for a minute and planted at
once, all grew but one—very slowly, however, and with more or less
appearance of injury, the plants averaging only 3% inches in height
four weeks after planting. Soaked in coal-tar for 16 hours, only 11
kernels grew out of 50, and the plants from these were all stunted and
otherwise injured.

Tar-water, obtained by pouring water upon coal-tar and stirring
the two together and leaving for a time to settle, did no injury to 50
grains of seed soaked for half an hour or an hour.

Camphor was imperfectly tested by soaking seed-corn for 10 min-
utes and for an hour in a saturatéd solution of the gum in alcohol.

12

After 10 minutes’ soaking all the seed grew, but after one hour’s
treatment all but 2 kernels out of 50 were killed. A light application
of the solution at the rate of about 3 ounces to the gallon of corn
produced no effect, 49 kernels out of 50 growing, and the plants being
uninjured and of maximum height after 3 weeks.

The more important of these statistical data are brought together
in the table following.

PRINCIPAL PoT ExPERIMENTS WITH REPELLENTS, 1906

No Treatment of Seed. Check Pots

= ——_ = See — ——

SS
No. of kernels | Percent to grow

INOREREARIMODE Ente che ey eee een. ey eee carr ae 1750 96

Treatment of Seed with Kerosene

Quantity or time No. of kernels Percent to grow
1 (Oz 2,622 tO ONE PallOn.is sc siercs-aaee ene os 800 98
2 02.—3)4 Oz. tolone gallOnen ly -1-1-e6 are 200 92
LOsmimutes}soalkuin gtirs secs ae eae eee ape eee sea 200 | 88
ZO metres Whe Dy Sab syscshole caguicneuee oe ae Nee ented: ears 200 93
4 hours’ Sai eres rer ors Sea ans cea Rees 50 z
Gir De lak rninreters Som ertanineactotes 200 82

Treatment of Seed with Crude Petroleum

Time in petroleum No. of kernels | Percent to grow
Stor LO mines 29% 1d. sassye «fecha orescence asneten al ere 100 91
20ito sO ae SAD bl embaaeed eine MeV oR ares cos SI 100 56
TiS r oT DO UNS: cartes wo Acre ca cee nel oy ge rnaon t ne 150 Hl
MOO SAA igh eanatn oestriol Ps a 250 54

Treatment of Seed with Oil of Lemon and Alcohol

Quantity or time No. of kernels | Percent to grow

Oil of lemon, 10% mixture: | |
Boz, to wallon-ob corn sats. ds compan | 100 | 98

20 to'60 minutes soaking” > cannes wenn. 150 | 87

19 thours isoaking’ 1);)..5sccrtanei sete rebteaher esses | 50 | 58
Oil of lemon, 33% % mixture: |

Oo, top 0 Smintites soaking sot eeaaerere en isfee 100 | 99

20 to 30 s bent “abo hhe BR yc 100 | 22) 2

erat

Ise

Treatment of Seed with Solutions of Carbolic Acid

Strength | Time | No. of kernels | Percent to grow
2 percent Wawro S0laninitesit. eb as eslee icon 200 | 99
5 + 5 to 30 choos Dp tile Near) Sie Sate meee ok yet 200 96

10 ¥ 5 to 30 ie gly cue encase bas ore aR yee 200 9

30 4 (BORtOrS Olea vee asi cet cit hia Weiaier sl 200 il

Treatment of Seed with Formalin Solutions

Strength

| Time | No. of kernels | Percent to grow
4 percent par SObminates Aer eres. | 200 94
25 i | & ian, adhe bec Bot Eee | 50 74
25 es NO) wonstO seen oe Gos ce gunedcoodon 150 34

50 aN PSU RMOIAIICE Sines atoveyshe wie h vhar aoa aon > aks as | 50 0

Treatment of Seed with Alcohol

Time in alcohol No. of kernels | Percent to grow

Common alcohol:

Sy ttev eA O ea vey Uotols\ctc Oy cacaee fink COPIES St Pn Rn pee ieee a 150 98

SUPITMTUUILES sn tae foeetecwal Roce cae ee Mlaaee ere ernie oe 50 66
Wood alcohol:

SeromlOrmmirtesee wrciccts cts sein ere a resehe ke 100 95

DOMAIMULES er wise aise Se ictal c neeree stores Saranetel Te 50 74

60 Pega a date scree Nice a erederteirehel a coh eaiehevaereios 50 | 14

Treatment of Seed with Lysol in Water

Strength | Time or quantity No. of kernels | Percent to grow
HSPeccente eo tO eMINMteS .tcreal ale Ferrel ole re- 200 99
2 ee | 5 to 20 Ae NOT ee Strata Rene a Bate 150 95
2 ‘ DMN LIGSI ae eisai sense eh Sy oLaKn era hiekales | 50 68
5 “ ie SrromlOnmaimutesccics stein ree fase 100 96
5 5 AAO an ANDO Cae coche ato Doe eae oe Oe 50 78
5 ~ eo TOUTS tes, | erat Reeser al cerca ayers ea 50 | 0
10 S ie Sstoel Osminuteseemer acest oe 100 78
10 oy 20 tONO Os ahead. (Bry ice reomn ata cosine 100 | 0)
100 = [ager TASH OLE CAS, Heo ests Gc a UR Oe een oee 50 2,
100 ug WlgozstotealleaGonn ince i-t ceeires = ack 100 73
TOD >" ASOZ, AOMPAlCOLIM gah. oinc8 heya iE 100 92

A Corn-FIELD EXPERIMENT, 1906

Precautions preliminary to a large field experiment having been
thus taken, and injury to the seed thus guarded against, the way was
open to a practical test of the most promising of these repellents, to be
made by planting parts of the same field with corn treated with each
of them, leaving other parts untreated as a check.

14

THE EXPERIMENTAL FIELD

For this purpose, after a careful examination of many fields in
the vicinity of Elliot, Ford county, by one of my assistants, Mr. E. O.
G. Kelly, choice was made of twenty acres of dark rich loam, level
and of a uniform quality, on the farm of Mr. James Jones, one and
a half mile northeast of Elliot.

This ground had been in corn the preceding year, and it was
heavily infested by the corn-field ant. The old stalks were harrowed
down and burned April 24 and 25, and the field was plowed to a depth
of 4 to 6 inches April 26 to 28, with a gang of two plows, each cutting
a furrow 15 inches wide. It was then twice harrowed with a toothed
harrow—the last time May 7—and was planted May 8 to 11, in rows
80 rods long, 372 hills to the row, the hills 344 feet apart each way.

INSECT INFESTATION OF FIELD

A number of ants’ nests in this field, critically examined previous
to April 26, all contained eggs and recently hatched young of the corn
root-aphis. The degree of infestation of the field was ascertained by
counting the nests of the corn-field ant overturned by the plow.
Eleven hundred and forty-two nests were found in 62 furrows cross-
ing the field and aggregating 151% miles in length. This was at the
rate of 74 ants’ nests to the mile of furrow, 516 to the acre, or 10,320
to the entire field.

Nineteen days later 250 hills of the corn in the check plots of this
field were found to harbor an average of 62 ants to the hill,—equiva-
lent to nearly five millions in the entire field; and within six weeks
from the time of planting, the check hills averaged 162 root-lice,—
equivalent to twelve and a half millions of those insects to the field.

Even this statement does not fully describe the burden of infesta-
tion with which our experimental field began the year. During his
tramp of 15% miles, backward and forward behind the plow, Mr.
Kelly counted also 6519 white-grubs exposed in plowing, which is
at the rate of nearly 3000 of these destructive insects to the acre, or
59,000 for the entire field. Of course only a small part of the grubs
in the soil were brought to view by the plowing, and this number
may reasonably be trebled or quadrupled for an estimate of the whole
number present.

DESCRIPTION OF THE EXPERIMENT

The ground being thus selected, found thus infested, and made
ready for planting, an experiment was started May 9 with four
principal substances—kerosene, oil of lemon, formalin, and carbolic
acid—and with three others, to which less importance was attached—
flowers of sulphur, chlorid of lime, and “Rex Dip.” The experiment
was laid out as follows:

The first 50 rows from the east side of the field were planted with
corn not treated, and available, consequently, as a check. The next
24 rows were planted with seed treated with a 3 percent solution of

é nto tas

1 ——

1

crude carbolic acid in water. Three ounces of this mixture was
poured upon a gallon of corn, which was thoroly stirred until every
kernel was moistened, the surplus being allowed to drain away. Not-
withstanding its slightly moist condition, the corn ran out of the
planter as well as if it had been dry.

The 20 rows next this strip were planted with ordinary seed left
as a check; and for the next 12 rows the corn was treated with kero-
sene, half a fluid ounce of the pure oil being thoroly mixed with a
gallon of the seed just before it was put into the box.

The next 12 rows were planted with corn treated with oil of
lemon. For this purpose one part, by measure, of the oil was mixed
with nine parts of ordinary alcohol, and 3 fluid ounces (6 tablespoon-
fuls) of this solution was thoroly stirred into a gallon of corn, which
was then drained and put at once into the planter box.

The next 8 rows were left as a check; and for the plot of 12 rows
adjoining, the seed was treated with formalin reduced to a 3 percent
solution by the addition of water. Three ounces of this mixture
was thoroly stirred with a stick into a gallon of corn, which was then
carefully drained and put into the planter at once.

On the 11th of May, in another part of the field, 28 rows of corn
were planted, the seed for which had been treated with a solution of
lime and sulphur known as “Rex Dip,” | part of this substance to 10
parts of water. A pint of the mixture was poured upon a gallon of
seed-corn, which was then thoroly stirred. and after 20 minutes’ soak-
ing the seed was drained, being stirred in the meantime to dry it
partially, in order that it might work well in the planter.

Next to this plot. a strip of 8 rows was left as a check, and the
following 8 rows were planted with corn treated with flowers of sul-
phur. The grain was dampened slightly to make the sulphur stick,
and a quarter of a pound of the latter was stirred thoroly into a gal-
lon of corn, completely covering all the kernels.

Finally, 16 rows adjacent were planted with seed which had been
soaked for 10 minutes in half a pint of a saturated aqueous solution
of chlorid of lime to the gallon of corn.

The ground was reported to be very dry at the time of planting,
and the young weeds in the field were all dead as a consequence. Its
condition was evidently not unusual, however, since a heavy rain is
recorded for May 2, and another followed May 8.* Nevertheless
there was some deficiency of moisture, for the soil was lumpy after
plowing. and the sprouting of the seed was said, on the 22d, to have
been delayed somewhat by dry weather.

Fifty hills of corn were examined on the latter date in one of the
checks, and 15 were found to contain root-lice and ants. Odors of
carbolic acid. oil of lemon, and kerosene were still perceptible on the
kernels a week after planting, but the corn treated with formalin had
no noticeable smell.

“Rains fell at this place as follows: April 8, 13, 24, 30 (shower); May 1, 2 (heavy), 8,
18 (slight), 26 (heavy), 27, and 30. The fields and roads were said to be muddy June 1.

16

RESULTS OF THE EXPERIMENT. FIRST INSPECTION

The first general inspection of the field was made by Mr. Kelly
May 28 to 30, when 800 hills were dug up in the various plots and the
ants and root-lice were carefully counted* Two hundred and fifty of
these hills were from the check plots, 100 each from the principal
experimental plots—those with carbolic acid, kerosene, formalin, and
oil of lemon—and fifty each from the three remaining plots whose
seed had been treated with sulphur, “Rex Dip,” and chlorid of lime.

Percentages of hills infested 19 days after planting.—At this time,
a month after the plowing of the field and 19 days after planting,
57 percent of the 250 hills dug up in the check plots were infested
by ants. The corresponding averages for each of the four principal
experimental plots were as follows: oil of lemon, 23 percent infested ;
kerosene, 31 percent; formalin, 33 percent; and carbolic acid, 49 per-
cent. The ratios for the less important experiments, from each of
which 50 hills were dug up, were 54 percent for the sulphur plot, 70
percent for the “Rex Dip,” and 48 percent for the chlorid of. lime.
Otherwise stated. using the condition of the check plot as a basis of
comparison, the plot treated with the oil of lemon showed an improve-
ment of 60 percent in number of hills infested by ants; the kerosene
plot, a 46 percent improvement; the formalin plot, 42 percent; and
the carbolic acid plot, 14 percent. The three other plots showed no
improvement except possibly the chlorid of lime.

Not all the hills containing ants at this time contained root-lice
also, but there were no root-lice where there were no ants. The ratios
of infestation of corn hills by the root-aphis for the five plots were
as follows: checks, 53 percent; oil of lemon, 14 percent; kerosene,
20 percent; formalin, 28 percent, and carbolic acid, 39 percent. The
corresponding ratios of improvement in respect to aphis infestation
were these: oil of lemon, a benefit of 74 percent; kerosene, 62 per-
cent ; formalin, 47 percent; and carbolic acid, 26 percent.

It is a suggestive fact that while the infested hills of the checks
contained an average of 21 ant larve to the hill, none of the hills
treated with the three most odorous substances, oil of lemon, kerosene,
and carbolic acid, contained so much as a single larval ant. In the
formalin plot, however, there were about as many larve to the in-
fested hill as in the checks. As the ants take assiduous and anxious
care of their young, the absence of larve from the treated hills, even
where the workers themselves were numerous, is evidence that con-
ditions there were offensive to the ants.

In view of the observed effect of an overdose of kerosene on the
young plant, as described in the earlier part of this article, it is im-
portant to note that no dwarfing or distortion of the corn plants was
seen in any of these experiments.

Average numbers of insects 19 days after planting.—Turning now
to the number of both kinds of insects in these plots, irrespective of

*The owner of this field was paid at an agreed rate for all hills dug up or injured in
the course of our experiments.

os

*'’~

17

the number of hills of corn infested by them, we find an average of
66 ants and 23 root-lice to the hill in the checks, 9 ants and 2 root-
lice to a hill in the oil of lemon plot, 16 ants and 3 root-lice in the
kerosene plot, 30 ants and 6 root-lice in the formalin plot, and 25 ants
and 12 root-lice to the hill in the plot treated with carbolic acid. The
ratios of benefit in respect to fhe numbers of root-lice were conse-
quently as follows. With respect to ants: oil of lemon, 86 percent
benefit; kerosene, 76 percent; formalin, 55 percent; and’ carbolic acid,
62 percent. With respect to root-lice: oil of lemon, 83 percent benefit ;
kerosene, 87 percent; formalin, 74 percent; and carbolic acid, 52 per-
cent. The use of the three secondary applications, on the other hand,
“Rex Dip,” chlorid of lime, and sulphur, had evidently accomplished
comparatively little. In the plot treated with chlorid of lime there
were 31 ants and 25 aphids to the hill; in that treated with sulphur,
45 ants and 31 aphids; and in the plot treated with “Rex Dip,” 72
ants and 53 aphids—the last two of these numbers being actually
greater than those for the checks.

The total normal infestation of this field at fits time, as shown by
the condition of the checks, was 240,000 ants and 124 000 root-lice to
the acre. The aphids were all in hills of corn, while only so many
of the ants were there established as was necessary to the purposes
of the colony, the central home of which was commonly outside the
hill between the rows of corn. The data of the foregoing discussion
are briefly presented in the tables on page 20.

RESULTS OF THE EXPERIMENT. SECOND INSPECTION

June 21, 43 days after planting, a second count was made of both
ants and aphids in 250 hills—50 hills each for the check and for the
four principal experimental plots. At this second counting, 73 percent
of the hills in the check were infested with ants, 22 percent of those
in the oil of lemon plot, 44 percent in the kerosene plot, 46 percent
in the formalin plot, and 76 percent in the plot treated with carbolic
acid. A few hills contained ants which did not contain root-lice also.
The corresponding ratios of infestation by root-aphids for these five
plots were as follows: check, 73 percent; oil of lemon, 20 percent;
kerosene, 40 percent; formalin, 46 percent; carbolic acid, 74 percent.
In respect to number of insects in each lot of 50 hills dug from the
various plots, we find the difference quite as marked. The check plot
contained 39 ants and 166 aphids to the hill; the oil of lemon plot, 8
ants and 18 aphids; the kerosene plot, 16 ants and 52 aphids; the
formalin plot, 20 ants and 64 aphids; and the carbolic acid, 32 ants
and 139 aphids.

Converting these data into percentages of improvement, by com-
paring the ratios for each experiment with those of the check, we
find that the benefit to the plot treated with oil of lemon was 70 per-
cent in number of hills infested by ants, 73 percent in hills infested
by aphids, 79 percent in the number of ants in the plot, and 89 percent
in the number of aphids. The corresponding ratios of benefit for the

18

kerosene plot are 40 percent in hills infested. by ants, 45 percent in
those infested by aphids, 59 percent in number of ants, and 69 percent

in number of aphids.

In the formalin plot the benefit for hills infested

by ants and by aphids was 37 percent for each, .and the benefit in
number of ants in the plot was 49 percent, and in number of aphids,

61 percent.

In the carbolic acid plot, on the other hand, the numbers

of hills infested by ants and by aphids were somewhat larger than

in the check.

INSPECTIONS OF May AND JUNE, 1906

Percent of Hills infested

By ants:
After 19 days
After 43 ‘‘

By aphids:
After 19 days
After 43° -**

Ants:
After 19 days
After 43 ‘“

Aphids:
After 19 days
After 43“

After 19 days

Oil of K Carbolic F li
moe erosene aaa ormalin
23 31 49 33
29) 44 76 46
14 20 39 28
20 40 74 46
Insects to the Hill
Oil of Rerssene Carbolic ms -
lemon eee Acid Formalin
9 16 25 30
8 16 32 20
> 3 12 6
18 sy) 139 64

Benefit in hills infested

| After 19 days

Percentages of Benefit from various Treatments

Oil of lemon
Kerosene
Carbolic acid |
Formalin

By S| ey
ants | aphids
60 74
46 62
14 26
42 47

After 43 days

By
ants

70
40
00
37

|
!

| By | Z

| aphids | Ants | Aphids

ase Ses eee eae

|

jes, 3) SSB Geol 8S
457) | eam | 87
00 | 62 | 52
Bio teen 74

Benefit in No. of insects

After 43 days

Ants | Aphids
79 80
69 |. 69
18 as)
49 | 61

aa

19

FIRST AND SECOND INSPECTIONS COMPARED

Comparing next the conditions found May 28 and June 21, we find
that the number of hills infested in the check had increased between
these dates from 57 percent to 73 percent for ants. and from 53 per-
cent to 73 percent for the aphids; while the number of ants to the
hill had diminished from 66 to 39 and the number of aphids to the
hill had increased from 23 to 166. The number of the aphids, it will
be seen, had increased sevenfold.

Rate of increase of root-lice in the field—The period of active
multiplication of the root-aphis in the field commonly continues until
early October, approximately six times the period within which we
found a sevenfold increase. If this rate of increase were maintained
until the end of the season, the 124,000 aphids per acre found May 28
would multiply by October 1 to more than 14,340,000,000, or 39,000 to
the hill of corn. This computation of the actual rate of multiplication
of the corn root-aphis in the field is sufficient to account completely for
any amount of injury which these insects may do to the crop under
conditions favorable to their increase.

RESULTS OF THE EXPERIMENT. THIRD INSPECTION

On the 17th of July Mr. Kelly reported a conspicuous difference
in height between the corn on the experimental strips and that on the
checks—a difference so great, indeed, that. as one looked across the
field, it seemed to lie in alternate ridges and hollows, the ridges corre-
sponding to the experimental strips and the hollows to the checks. The
ground being perfectly level, these differences were evidently due to
the more rapid growth of the corn in the experimental plots; or, more
correctly speaking, to an arrest of growth in the checks resulting from
the greater drain of insect injury where the corn had not been pro-
tected by a previous treatment of the seed. Visiting this field July 21,
I noticed that the central rows of the check strips were shortest, and
the central rows of the experimental strips were tallest, the transition
from one to the other being gradual. On passing down a central
check row, the highest stalks reached, on the average, to my elbows;
and on walking down the central row of an experimental strip, the
tallest stalks were found to reach nearly to the top of my head.

To verify this observation, measurements were made of the tallest
stalks in 214 hills of one of the checks, and in 157 hills of the carbolic
acid plot. The first of these averaged 36 inches and the second 62
inches. The height of the corn in the check strip was less by 42 per-
cent than that in the experimental plot, and this was the measure of
an injury by insects in the former which had been prevented in the
latter by the treatment of the seed. This striking difference was quite
as obvious to the eye August 27, after all the corn had tasseled.

RESULTS OF THE EXPERIMENT. FOURTH INSPECTION

What proved to be a final inspection of this field was made Sep-
tember 20, when the hills and both fertile and barren stalks were

20

counted in six rows of the checks and in three rows each of the four
experimental plots.

Number of hilis of corn to the row.—The following were the aver-
age number of hills of corn to the row 372 hills long. In the check,
329% hills; in the carbolic acid plot, 328; oil of lemon, 326; formalin,
317; kerosene, 282. In other words, 11.4 percent of the places for
hills were without corn in the check, 11.8 percent in the carbolic acid
plot, 12.4 in the oil of lemon plot, 14.7 percent in the formalin plot,
and 24.2 percent in the plot treated with kerosene. The differences
between the check on the one hand and the plots treated with carbolic
acid and oil of lemon on the other are doubtless insignificant, and per-
haps the formal’n plot should be included in this statement. Consid-
erable importance must be attached, however, to the fact that more
than twice as many hills were missing in the plot treated with kero-
sene as in the check, three rows of the kerosene plot containing 271
missing hills as against 255 missing from six rows of the check. In
view of the injurious effect of kerosene upon the seed, as shown by
our insectary work and by our field experiment of 1905, we can only
suppose that some injury was done even by the minimum amount of
kerosene used in this experiment of 1906.

Number of stalks of corn to the row.—The number of stalks to
the row in these various plots was as follows: check, 621; oil of
lemon, 641; formalin, 545; carbolic acid, 543; kerosene,:511. The
plot treated with the oil of lemon, it will be noticed, contained 20
stalks more to the row than the check—an increase of 3.2 percent,
apparently due to a complete destruction of the plants by the insects
in the check, against which the experimental strip had been protected
by its treatment. In the remaining plots, on the other hand, the num-
ber of stalks was diminished in the experimental plots from 12.2 per-
cent in the formalin strip to 17.5 percent in the kerosene—a diminution
which can only be accounted for on the supposition that a certain
amount of the seed was injured by these substances. Indeed, taking
as a basis of comparison the number of stalks in the plot planted
with seed which had been treated with oil of lemon, we find the loss
of plants in the kerosene strip to have been 20 percerft and that in
the other plots to have been approximately 15 percent—all due, so far
as one can see, to injury to the seed by the substances employed.

Ear-bearing stalks to the row—The most significant comparison
of these plots was made by a count of the stalks bearing ears, the
number of barren stalks varying greatly according to the treatment
applied. In the check plot were 412 ear-bearing stalks to the row;
in the oil of lemon plot, 526; in the carbolic acid plot, 505; in the
formalin plot, 485; and in the kerosene plot, 439,—all four numbers
considerably larger than those of the check. The greatest improve-
ment to be seen in this final test of treatment is in the oil of lemon
plot, where the yield in ear-bearing stalks was 27.7 percent greater
than that of the check. the corresponding ratios of increase for the

remaining plots being as follows; carbolic acid, 22.6; formalin, 17.7;

‘es

pa
xX

21

kerosene, 6.6. It will be noticed that notwithstanding the fact that
the kerosene plot contained an average of 110 stalks per row fewer
than the check, the number of ear-bearing stalks was 27 per row
greater than in the check. Even the kerosene, tho it seemed to have
lessened the stand by an injury to the seed, had increased the yield
nearly 7 percent by protecting the corn against the drain of root-louse
attack, thus preventing the blighting of a considerable percentage of
the remaining stalks. Under the conditions present during this season
and in th’s field, all these treatments had an ultimate beneficial result,
according to the data thus repeatedly and carefully collected, the
actual ratio of benefit being, however, nearly four times as great from
the use of the oil of lemon as from the use of kerosene.

INSPECTION OF SEPTEMBER 2()

Oilof | Carbolic

l

| |

| Formalin | Kerosene
|

| Check lemon | acid |
Hills to the row........ 329.5 3060 n | ea2e |! Bi? 282
Stalks to the row..:....| 621 OAL eI SeSda las! 545 511
ee eaGt ral es yhOS mill) Pe AB Sr ann) 439

Fertile stalks to the row | 412

Thru an unfortunate failure of the tenant farmer controlling this
field, I was disappointed in my original plan to harvest the plots sepa-
rately, measuring and weighing the product of each in comparison,
and the difference in yield, apart from these differences in number, can
only be inferred from Mr. Kelly’s note of September 20, which reads:
“The ears and the stalks in the checks were very small, much smaller
than on any of the treated plots. The ears and stalks in plots treated
with oil of lemon and carbolic acid were much larger than those in
the other treated plots, and much larger than in the checks.”

GENERAL FINAL RESULT

As a final statement of the most important result of the various
treatments of seed-corn here described, it may be said that. according
to the data of this experiment, the oil of lemon treatment increased
the yield 1159 ear-bearing stalks to the acre; the carbolic acid treat-
ment, 945 such stalks; the formalin treatment, 742; and the kerosene
treatment, 274.

The expense of all the treatments was trifling, that of the most
costly—the oil of lemon—amounting to about ten cents an acre for
material used.

CoMPARISON OF INFESTED FIELDS

That the’ infestation of this field altho heavy enough to reduce
the yield by at least one third, was not by any means extreme is shown
by conditions reported by Mr. Kelly from a field of 20 acres on another
farm near Elliot, as shown by an inspection made September 14. This
latter field was so heavily infested by the corn root-aphis that the

22

crop was virtually destroyed. Ina plot of 2000 hills were 2467 stalks,
of which 95 percent were less than 4 feet high, and 75 percent were
20 inches high or less. In this entire plot were only 95 ears—a num-
ber equivalent to 169 ears to the acre—and these were mainly nubbins.
Eleven hundred and thirty-eight h‘Ils contained still living plants, and
in 1093 of them the root-aphis was still present. Four hundred and
sixteen hills which were either dead or withered, dry, and barely
living, all contained the root-aphis at the time, or showed by the bur-
rows of ants along the roots that they had been previously infested.
In a neighboring field practically uninfested, with which this is to be
compared, 2000 hills contained 4324 well-grown stalks with 4024 ears,
only 201 of which were nubbins.

More EXPERIMENTS NECESSARY

Our field experiment of 1906, decisive as it seems, is, of course,
to be taken as applying exactly only to similar, if not identical, con-
ditions—a similar soil similarly prepared, equally infested with the
corn root-aphis, and subject to similar weather conditions—and with
a treatment of seed identical with ours in all particulars, including
materials of the same quality and strength. How far the results
here described may be expected to apply to a different soil, less
heavily, or even much more heavily. infested, more thoroly prepared,
and planted during either a very wet spring or a very dry one, with
a less perfect seed, treated with slightly different chemicals and com-
pounds, can be learned only by repeated and varied experiment. In-
deed, the possibilities of useful experiment with this method are almost
innumerable, and can scarcely be exhausted by any one office, however
well manned and equipped, and however long its program of opera-
tions. The procedure is so simple and so inexpensive, however. that
any careful corn grower can test it, and its usefulness in ordinary
practice must be finally determined by such general, careful, and oft-
repeated trial as farmers themselves may think it worth while to
make. It is my purpose to test it by similar operations in several
successive years, the results of which will be reported in later articles
of this series, and ‘t wll greatly help us to an early practical conclu-

sion if others interested will experiment carefully, and report upon |

their methods, materials, and results.

AN ADDITIONAL, MINor TEST

Further special tests on the reactions of ants to the various re-
pellents of our list were made by planting, close around burrows of
these ants in the field, a few hills of corn, one of which was left un-
treated as a check, the remainder being treated with one of the repel-
lents as a test. “Rex D'p,” formalin, carbolic acid, oil of lemon, kero-
sene, chlorid of lime, sulphur, and common lime were tested in this
way. The hills so planted were thus immediately exposed to infesta-
tion, and any failure of the ants to occupy them would be particularly
significant. The test plantings were all made by Mr. Kelly April 5,

~y
~— ——e

23

in a field near Elliot, and the results were ascertained April 22, when
the corn was from 3 to 5 inches high. All the test hills surrounding
the ants’ nests, including both check and experimental plantings, were
thoroly infested by ants and root-lice where the seed had been pre-
viously treated by rolling it in lime or sulphur, by soaking for 10
minutes in a saturated solution of chlorid of lime, and by soaking for
10 minutes in a 10 percent mixture of the “Rex Dip.’ In the lime
experiment, 5 hills were planted immediately surrounding an ant’s
nest, one of these being reserved as a check; in the sulphur experi-
ment, 4 hills were so planted; and in that with chlorid of lime, 4 hills.
In that with “Rex Dip,” 7 hills were planted around 2 separate nests
of the ant. The results of these experiments thus agree with those of
our more general test of plot plantings in the field.

As a test of the formalin treatment of the seed, 2 ants’ nests were
surrounded by 7 hills of corn, 3 around one and 4 around the other.
In each case one of the hills was planted with untreated seed, and the
seed for the others was soaked in a 4 percent solution of formalin,—
for those around one nest for 5 minutes, and for those around the
other for 10 minutes. After 17 days, both check and experimental
hills were all completely and uniformly infested by the ants.

In an experiment with the oil of lemon, 4 hills were planted around
another ant nest, three of them with treated grains and one as a
check. Here also all the hills were infested May 22.

In a corresponding experiment with kerosene, 10 hills were planted
so as immediately to surround 2 nests of the ants, two of these hills
being reserved as checks and the other eight planted with corn which
had been moistened with kerosene by putting a single drop to a dozen
grains and rolling these together until all were oily. By the 22d of
May one of these nests was completely abandoned by the ants, which
had apparently formed another nest about three feet away. There
were no aphids on roots of either check or experimental hills. The
other nest was still occupied, and there were a few aphids on the
roots of the check, but none of either ants or aphids on the experi-
mental hills.

Finally, two nests were surrounded by 8 hills, 6 of which had been
treated with a 3 percent solution of carbolic acid—in the one case
soaking for 5 minutes and in the other for 10. In the former case
the roots of the check hill were covered with root-lice attended by a
few ants, while those of the three experimental hills had neither ants
nor aphids on them. In the latter case the ants had abandoned their
nest, and neither checks nor experimental hills were infested.

These results differ, it will be seen, from those of the plot plant-
ings in the fact that, while carbolic acid and kerosene apparently
kept the insects out of the treated hills for three weeks, oil of lemon
and formalin, as well as a number of other substances tested, were
without effect.

24

GENERAL PROGRAM OF PREVENTION

In the light of what we now know concerning the corn root-aphis,
the following measures of precaution are to be recommended as a
practical program.

1. A short rotation period in corn, especially during relatively dry

years. A single year in corn is better than two years, and a period

of two years is better than one of three. Especially if the crop was
visibly injured by the root-aphis the preceding year, or if more than

twenty ants’ nests to the mile are turned up by the plow, it is best |

that the field should be put into some other crop than corn—which
other is a matter of indifference, since no other is liable to injury by
the corn root-aphis.

It must be remembered, however, that even a field in corn for
the first time may become infested during the season by means of
winged root-lice coming into it from other fields in its neighborhood,
this infestation perhaps beginning as soon as the corn is up; and that
the rate of multiplication of these insects is so enormously rapid, under
favorable conditions, that such a new infestation sometimes reaches
destructive numbers before the first season is over. Even the shortest
rotation is consequently not a complete preventive where the root-
aphis has become so generally prevalent as it now is in most parts of
the Illinois corn belt. This is, however, the most reliable of all known
measures of prevention, and has the very great additional advantage
that it affords complete protection against another of the great insect
pests of the corn field, the notorious northern corn root-worm (Dia-
brotica longicornis.

2. A deep, thoro, and repeated stirring of old corn ground 1n fall
or spring (or, better still, in winter, where possible) as a preparation
for corn-planting. So quick a rotation as that advised in the preceding
paragraph is perhaps not always practicable, and is at any rate often
unwelcome and will not always be practiced. If corn is to be planted
on ground more or less infested by the root-aphis the preceding year,
injury by this insect may be greatly diminished by such a preparation
of the soil as will repeatedly break up the underground nests of the
ants and scatter the contents of these nests, consisting of the eggs and
young of the ants together with the root-lice and their eggs, thoroly
and repeatedly thru the dirt. The burrows of these ants do not often
reach to a depth of more than six inches, and if plowing to this depth
is followed by a deep stirring of the ground with a disk harrow, or
better, with a corn cultivator set into the ground as far as possible,
the attempts of the ants to recover their propery and to reconstruct
their nests are greatly disturbed and rendered largely fruitless. The
more thoroly, frequently, and deeply the ground is stirred in the in-
terval between the first plowing and the corn-planting, the fewer will
be the root-lice in the field in the beginning of the season. By this
means a check will also be placed upon the increase of the ants them-
selves, by the destruction of their helpless maggotlike young which
they have brought thru the winter in their nests. Furthermore, the

25

young weeds in the field on which the root-lice are dependent for food
until the corn begins to grow may thus be so thoroly destroyed as to
result in the starvation of the insects. Fortunately the labor of this
treatment of the field will usually be more than repaid by an improve-
ment of the corn crop independent of all protection against aphis in-
jury, this being practically the preparation for corn especially recom-
mended by our best teachers of high-grade agriculture and practiced
by some of our most successful corn farmers.

It should be clearly understood, however, that this measure will
not destroy all the root-aphids in the field. In a few cases ants’ nests
will go so deep that a part of their contents will be undisturbed by the
plow, and will thus remain as centers of infestation from which the
ants and aphids spread later to reoccupy the field. Furthermore, the
corn-field ant, even under these difficult and discouraging conditions,
will sometimes search out and bring together again at least a part of
the scattered contents of its burrows.

The outcome of several carefully conducted experiments with this
cultivation method of preventing the root-louse injury, is given in
Bulletin 104 of the Illinois Agricultural Experiment Station, pp. 102-
123, and also in the Twenty-fourth Report of the Illinois State En-
tomologist, pp. 8-29.

3. The maintenance and increase of the fertilty of the soil. The
richer the ground and the more thrifty the crop the less, other things
being equal, will be the injury to plants by the root-louse. We have
no present evidence that these insects thrive any the less or multiply
any less rapidly on the thrifty corn plant than on one poorly nour-
ished, but there is, of course, no doubt that the plant itself suffers
most under insect attack when it has least surplus of vigor and sap
to spare. In this respect also, the corn root-aphis helps to enforce
the teachings of a better agriculture, increasing the penalty of a poor
management by still further diminishing the yield of a deteriorating
soil.

4. Finally, the use of repellents on the seed as described in this
paper. This is still an experimental measure, and evidently can not
be commonly relied upon until we know more of its general and
average results. It seems to me desirable, however, that a consider-
able plot should be planted each favorable year in each suitable field,
with seed treated by one or the other of the odoriferous repellents here
discussed, or, still better, perhaps, by one of the strongest-smelling
fertilizers, to be applied by means of a fertilizer dropper ; and that the
consequences of this treatment should be carefully studied by a com-
parison of the product of this plot with that of adjacent parts of the
field. By a favorable year- is meant one in which the spring is of a ~
fairly average character—a little drier than normal, perhaps—and in
which, consequently. the seed is likely to grow quickly and the plant to
get a good and early start. By a suitable field' is meant one in corn
for a year or more preceding, and in which nests of the corn-field ant
are turned out in plowing at the rate of some fifty or sixty to the mile

26

of furrow. If they are fewer than this it may be that, in a year favor-
able for corn, no sufficient injury to any of the plants will be done by
the root-lice to make any noticeable difference between corn growing
from treated and from untreated seed.

As a safeguard against possible injury to the kind of seed one
is using by the kind of materials one may chance to purchase, and in
view especially of the well-known differences in seed and the differ-
ences also in materials of chemical manufacture, each experiment
should be preceded by a seed-corn test, made in the usual form but
in a way to bring into comparison treated and untreated seed with
respect to the percentage of kernels to grow. In this way the possible
failure of an experiment and some loss of stand may be prevented.

HABITS AND: BEHAVIOR OF THE CORN-
FIELD: ANT, LASIUS NIGER
AMERICANUS

The little brown ant notorious for its injuries to corn, and called
by us, consequently, the corn-field ant, is not by any means limited to
corn fields, but is abundant in all cultivated lands, in pastures and
meadows, in dense forests, along hard pathways, and in the sandy soil
of dry sunny roads. One sometimes finds it nesting in rotten wood
or under bark, logs, or stones, and even opening up its underground
burrows to the surface between the bricks of sidewalks and pavements.
It is distributed ‘‘over the whole of North America, except the extreme
southern and southwestern portions, from the tree line on the highest
mountains to the sands of the shore.”* Wheeler says that it is the
most abundant of our ants, and hence of all our insects.

Its homes and habits have been chiefly studied in corn fields, and
there it forms rather extensive settlements, mainly centered in the hills
of corn, several adjacent hills so occupied by it being connected by un-
derground channels by way of which members of the same family may
pass from hill to hill. This is partly, no doubt, because in corn fields it
is usually in possession of plant-lice which live on the roots of corn and
which contribute to the support of the ants the fluid surplus of their
own food, but partly also because in the corn hills it is undisturbed by
the cultivator, which is likely to tear up its nests if they are established
between the rows.

CONTENTS OF THE NESTS

In the burrows of this ant one may find a rather mixed and varied
population, consisting of the eggs, larve, pupz, males, females, and
workers of the ants themselves, together with the various species of
root-lice harbored by them and certain kinds of mites which share its
underground habitations on terms of mutual toleration if not of active
friendship. In clover fields it is very likely to have in its nests many
mealy-bugs (Pseudococcus trifolii Forbes) of a species which infests
the roots of the clover plant, and these it treats as it does the root-lice
of the corn plant, seizing them and carrying them away when its nest
is disturbed, just.as it hurries out of sight its own maggotlike larve,
its egglike pupz, and its minute, spherical white eggs.

The contents of the nest are not precisely the same at all times of
the year. In winter, for example, one finds in it no males or pupz of
. the ants, as a rule, but only workers and larve, companion mites, and
the eggs of root-lice. In some of the large winter nests one or more
wingless queens or mother ants may be found, altho we have not been

*An Annotated List of the Ants of New Jersey, by Wm. Morton Wheeler. Bull. Am.
Mus. Nat. Hist., Vol. I., p. 393.

27

28

able to satisfy ourselves that this is true of all, or even of most, of the
winter communities of this species. A careful search and exploration
of all the tunnels and chambers of large nests have often failed to bring
to light a single queen. Sometimes, however, two or more queens may
be seen living contentedly in the same worker family, performing their
proper function of laying eggs for the increase of the colony. Besides
these large composite and evidently well-established communities, one
may often find single females in the ground, sometimes wholly alone,
and sometimes with a few of their own eggs, a few larve, and a small
number of workers which are mainly undersized, but with no root-lice
in possession and no companion mites. Late in fall these scattered
solitary females may have nothing with them in their pocketlike under-
ground cells except a small cluster of their own eggs. These minor
groups with a single female in charge, are the beginnings of a new
family, and do not often reach more than a score or so of individuals
by the end of the first year. The larger compound groups are older
families, how old in any given case we have no present means of
knowing.
BEGINNING OF A NEw COLONY

Beginning now with a single female, which came out from an
established colony as a winged ant but later broke off her own wings,
burrowed in the earth, and began to lay eggs for another generation,
we will follow the history of the new enterprise thru the first year,
so far as our notes and observations enable us to go. Females and
males hatching from pupz as winged ants in the underground nests
from June to October, swarm out of their burrows as if by common
consent in August or September. Such an occurrence was noticed by
Mr. H. Garman, at Urbana, at 5 p. m. September 14, 1885. Males
and females came rapidly up from their burrows under ground and,
climbing the nearest blades of grass, took flight one by one, in various
directions, the workers in the meantime running rapidly about in a
state of great excitement. The males perish before winter, and the
scattered females go into the ground, each making for herself an oval
or spherical cavity, the beginning of a new family home. Some of
these buried females begin to lay eggs in summer and fall—August 15
to November 10, as we have seen them—but others live there alone
until spring, depositing their first eggs, according to our observations,
from the first to the middle of May, and continuing to lay additional
eggs, a few at a time, until September. The minute, maggotlike, foot-
less, and helpless larvae begin to hatch from these eggs in June, and
this hatching process may continue until October. The first larve to
appear are fed by the female from the contents of her own stomach,
which, as she is said to take no food during this period, are believed to
come from the nutriment stored up in her own body.* We have found

*Charles Janet has lately shown that the muscles of the wings of the female, used only
for a few hours during her whole life, break down within her body into a food supply avail-
able for the production of her eggs and the nourishment of her young. Anatomie du Corse-
let et Histolyse des Muscles Vibrateurs, aprés le Vol Nuptial chez la Reine de la Fourmi
Lasius niger. Limoges, 1908.

—

29

the oldest .larve full grown and beginning to pupate from the 12th to
the 16th of June, and pupation continues, of course, thruout the
season, as larve from the later eggs successively get their growth.
The first workers to emerge from the pupz in these small colonies
come out early in July—from the 7th to the 11th of that month,
according to our experience—and the last emerge in October, or pos-
sibly in November.

From solitary queens brought in from the field April 26 to May 3,
1906, and kept in the insectary under natural conditions, the first eggs
were obtained May 8, 9, 10, and 15, and the first larvze from these eggs
June 4. The length of the egg stage in the various lots deposited by
these females varied from twenty-two to twenty-eight days. The larvze
began to pupat> about the middle of June, the larval period being, in
four cases, » xteen, seventeen, nineteen, and twenty-three days. The
first adult appeared in this cage July 7, and others emerged at intervals
thruout the remainder of the year, the pupal stage averaging about
eighteen days. Judging by these data, the time from the deposit of
the egg to the appearance of the adult is approximately two months.
In several cases where second egg-masses were laid on dates definitely
ascertained, these dates were found to coincide closely with the time
of pupation of larve from the previous lot of eggs laid by the same
female.

The notes of my field observers make no definite statements as to
the numbers thus produced during the first season of the queen’s inde-
pendent life, but three families reared under observation in our insec-
tary, in 1906, gave respectively, 8, 9, and 19 workers as the final product
of the season’s operations. These numbers are perhaps too small for
the average in the field, altho larger than those of families reared dur-
ing the first year by the carpenter-ant, as reported by Pricer in 1907.*
Forty-one first-year colonies of this latter species contained from 2 to
27 workers, with an average of 10; and 19 colonies of a related ant
(Camponotus ferrugineus) contained from 2 to 19 workers, with an
average of only 6.

The process of growth and multiplication are interrupted by
winter, during which the ants hibernate in a dormant state in whatever
stage they happen to have reached, resuming their activities in spring
at the point where cold weather arrested them. The workers open up
the nests to the surface, usually in late March or in April, the evidence
of this beginning of their seasonal activities being the appearance of
circular heaps of minute pellets of earth around the mouths of their
burrows. The young larve grow little, if at all, as long as the weather
is cool, but, fed and cared for by the workers, increase rapidly in size
as soon as the weather becomes warm, the oldest of them reaching the
pupal state as early as May. Whether males and females appear in the
family colony during this second summer is not definitely known, but
it is rendered very doubtful by the small size of the family during the

*The Life History of the Carpenter-ant, by John Lossen Pricer. Biological Bulletin, Feb-
ruary, 1908, pp. 177-218. $

30

first spring and by Pricer’s observations concerning the carpenter-ant,
from which he concludes that winged males and females do not appear
in the colony until it is more than two years old. Some support for
this conclusion as applying to our corn-field ant will presently be given.
We can not follow the history of the colony farther at this time, lack-
ing detailed knowledge of the rate of its increase and the form of its
organization. We only know that family groups enlarge to contain.
several hundred workers, and larve sometimes by the thousand, with
pupz, males, and queens in much smaller numbers.

SIZE OF COLONIES

The following table shows the number of ants of all stages con-
tained in 20 nests dug out in an oats field by Mr. Kelly August 28,
1906. The fact that the larger numbers are all multiples of 10 or 5
shows that these counts are not to be regarded as exact.

ANTS IN TWENTY NESTs, IN Oats FIELD, Aucust 28, 1906

5 g &

2 iS g C ea : 5 ® <
6 is Q. Ci ae Ze es 3
S 4 A, = ze Os Q a, qo
41 60 16 0 0 eR aca 118
75 50 16 0 0 eae pea 142
160 400 30 0 0 | 590)
183 435 15 wien | | 655
190 530 60 26 ae | |- 810
220.1 > »430 75 Oi ny Mae ceil Gace heey eed (e222
260 650 210 11 27 5) | [. 5s
280 340 120 $236 a0 el | [eee
330 150 240 6. ayer ray (0)
340 150 60 0 Be | aes
360 750 30 13 3 | | 1186
380 420 35 2 19.84 | 856
410 700 120 sie Raa Gera | 1265
475 7 aan Nate 0 164 | > B41
540 150 250 Ge ail ies DOR | Bees re
585 280 125 0 1b.) 1006
680 240 125 31 12 | 1088
740 310 180 iG Foun ile Seas sytem! | | 1264
860 200 160 Lig ors PATEL 1270

900 450 25 21 | BQ a | | 1434

It will be noticed, on examining this table—the figures for which
are arranged in the order of the number of workers in each nest—that
the first three colonies are of a different class from the remainder,
marked by the absence of winged ants of either sex, and by relatively
small numbers of worker larve and worker pupz. These numbers are
apparently too large, however, for a first-year colony, and are probably
the result of two years’ multiplication from the sole queen founder.
Possibly the third of the series, with its 160 workers, 400 larve, and
30 pupe, is a third-year family. The small number of males and

31

females in the remaining families as compared with the workers, larve,
and pupz, can not be explained without a better knowledge of the
economy of this species. It will be noticed that the fully developed
nests, that is, those containing ants in the various stages due at this
season of the year, vary in number from 655 to 1434, with an average
for the 17 larger nests of 979.

It is probable that families reach their largest size in grass-lands,
where they may multiply without disturbance year after year; and
consistently with this supposition Mr. Kelly found in following the
plow in a field of grass in April, 1906, some of the largest nests of
our record. In one nest were nearly 6000 larve and 300 workers,
with no eggs, no pupz, and no queen. Thirty-nine other nests in this
field were seemingly as large as this.

INTERCOLONIAL HOSTILITIES

The well-known but remarkable hostility of ants of one colony to
those of another of their own species is well illustrated by many of the
observations of my field and laboratory assistants.

For example, the first of April, 1906, a strange queen introduced
to a group of some forty workers of the corn-field ant confined in a
formicary, was ruthlessly attacked and killed by them as an intruder.
Precisely the same observation was made in another case April 27.

August 15, 1905, a wandering lone queen placed in a formicary
inclosure with five males from another locality killed two of them
the same day. During the following night two stray worker ants of
her species entered the formicary thru a crevice and attacked the
queen, one of them seizing her foot with its mandibles and holding
fast for an hour and a half. when, as it could not be compelled to
release the queen, it was killed to save her.

August 16, 1905, a strange male was first placed among twenty
workers in a formicary, but being instantly attacked it was transferred
to another containing only a lone queen—one who having rid herself
of her wings was presumably already fertilized. The male being dead
in the morning, the presumption is strong that the queen killed it. In
another case, occurring August 15, four males placed in the nest with
a strange queen were immediately attacked by her, and two of them
were presently killed. On the other hand, a queen ant still bearing her
wings, placed alone with a strange male August 21, made friends
with him immediately. The two continued to live in harmony, the
queen sometimes caressing the male and even apparently feeding him,
until the 26th, when she began to try to pull off her wings and refused
to have anything further to do with the male. September 6, altho still
bearing her wings, having failed in her efforts to remove them, she
began to lay eggs. This seems a possible case of fertilization of the
queen within the formicary, but direct observations to that effect are
wanting.

August 16, a male from one formicary put in with the workers of
another was immediately pounced upon by them, and would evidently
have been killed if he had not been promptly rescued.

29

02

August 15, worker ants taken from two different nests in the field
and placed in the same formicary began at once to fight. They kept
up their contest all night, and several of them were dead in the morn-
ing. By noon of the following day, however, fighting had ceased
and the two groups had separated, occupying different parts of the
enclosure. The larger group had taken possession of a corn plant
which had been introduced for the use of these ants, and the other
colony, which established itself near the edge of the formicary, seemed
timid and cowed, apparently fearing even to feed upon the syrup
offered them. The dominant group mined actively in the earth about
the roots of the corn, and appropriated the root-lice introduced into
the cage, evidently feeling themselves masters of their domain.

April 24, 1906, a colony of 100 worker ants with 200 larve of
various sizes, and eggs of the corn root-aphis, were brought in from
the field and established in a two-celled glass formicary. After they
had become thoroly at home, nine worker ants and a few ant larve—
strangers to the original colony—a bunch of aphis eggs, and some
young root-aphids, were introduced into this nest, the original family
being in the orange or dark cell and the newcomers in the other ceil
of this cage. As soon as the presence of the strangers was detected
they were attacked by the old colony, which dragged the adults about,
killing them one by one, ate up their larve, ate or pulled to pieces the
root-lice introduced with them, and crushed the aphis eggs. The root-
lice and eggs brought in from their own nest they were in the mean-
time caring for as usual.

August 7, some eggs of the corn-field ant brought in from the
field and placed with a colony of workers well established in an artifi-
cial formicary, were presently found by one of the workers and delib-
erately crushed, one by one.

These hostilities of ants to strangers may extend even to those
of their own sisterhood who have been away from home too long.
For example, a young worker separated from its formicary mates
August 21, kept alone, and returned to them twenty-one days later,
was immediately attacked by them and quickly killed.

The utility to the ants of this inhospitable savagery—this spirit of
ferocious clannishness—is doubtless to be found in their social organ-
ization, and in the necessity under which they live of keeping always
an active, compact, deeply interested group of workers completely
devoted to the care and nurture of their helpless young. No young
of any animal can be more utterly dependent than those of these ants,
and their feeding and protection must be the constant, consuming care
of the whole family group.

The workers are, on the other hand, among the most active and
enterprising wanderers and foragers among insects, traveling far and
wide on foot to distances which make it necessary for them to retrace
their steps carefully, whether by the aid of the sense of sight or by
antennal senses supposed to resemble what in us is the sense of smell.
The homing instinct and the nursing instinct are in them so strong as

reise

Oo

7
45

practically to rule their lives. They go abroad in search of food for
the family, and to the family they must return, however far they may
travel and into whatever difficulties and adventures they may fall by
the way.

These facts make it necessary that there should be in the economy
of ant society some self-acting, self-regulating apparatus for keeping
the family groups wholly separate and distinct, for making sure that
every foraging worker shall find its way back to its own companions
—that it shall neither be liable to lose its way completely nor likely to
attach itself to an alien family. From this point of view it is greatly
to the general interest that it should find a welcome and a permanent
home only among its immediate kindred and habitual companions, and
nothing could make this condition more secure than a universally
hostile reception to the wanderer in every other family group. Clan-
nishness in ants has thus the same justification that it has among
savage men. It is a means of maintaining the necessary concentration

.of the group for the care of the young, and hence for the preservation

of the race.
AREA OCCUPIED BY A SINGLE COLONY

Practical advantage was taken by us of this intolerance of ants.
towards those of other parentage to ascertain the limits in the corn-
field of a single colony or family group. Assuming that specimens
from adjacent hills of corn are members of the same family if they
affiliate peaceably, but that they belong to different families if they
fight, I instructed my field assistant to bring the inhabitants of adja-
cent hills into contact with each other in artificial nests until all those
affiliating with the original group used as a test were distinguished
from those about them who refused peaceable affiliation. By a care-
ful application of this method at Elliott, May 23, 1906, two family
areas were thus marked out.

The group of hills included in the first experiment ee an
area 10 hills in length by 7 in width, and 20 of these 70 hills were in-
fested by ants. Selecting the inhabitants of a hill from the center of
this tract for the purposes of this test, ants from the other infested
hills were placed with them successively. By this means it was found
that the inhabitants of ten of these hills were members of one com-
munity, harmonizing with each other perfectly when commingled. but
that those of the other nine were strangers to them, since the repre-
sentatives of these groups instantly fought when placed together. The
ten nests thus identified as related were distributed over an irregular
area about 30 feet long by 14 feet in greatest width, and were proba-
bly all connected by a network of underground channels. Hills inhab- -
ited by hostile ants were in many cases immediately next to others
occupied by members of this family group.

The second experiment covered a plot of 130 hills, 32 of which
were occupied by the corn-field ant. The occupants of 12 of these
hills affiliated peaceably, while the remaining 20 were rejected by the

34

original colony used in making the test. The family settlement thus
outlined, also irregular in shape, was about 30 feet long by i0 feet in
greatest breadth. There was no intermingling of hostile groups in
either of these family areas, all the ants occupying hills within the
-Eoundaries of each being on friendly terms.

RELATIONS TO OTHER SPECIES GF ANTS

Notwithstanding the almost invariable intolerance exhibited by
different families of the corn-field ant towards each other, they some-
times live on perfectly friendly terms with ants of other species, both
kinds mingling harmoniously in the same galleries among the roots of
the same hills of corn. One of the small red house-ants (Solenopsis
molesta) which often infests kitchens and pantries to the annoyance
of the housekeeper, is frequently found at home in the nests of our
corn-field species. A mixed settlement of these two ants found in a
field near Urbana August 31, 1905, and brought to the insectary and
established in a jar of earth, collected their larve and pupz into sep-
arate lots without contention, and continued for several days to feed
peaceably together from the same food supply. August 29 another
species common in corn fields, Formica schaufussi, was found by Mr.
Kelly inhabiting the nests of Lasius niger americanus, the larve and
pupz of both being, as he says, mingled in the same heap. Trans-
ferred to a Mason fruit-jar and brought to the insectary, they lived
together for two days in a Lubbock nest without fighting; but after-
wards hostilities broke out and all the Formicas were killed save two
which remained in hiding, and their pupz were thrown by their con-
querors into the ditch surrounding the nest.

BEHAVIOR WITHIN THE NEST

From a colony of ants obtained August 15 and established in a
Fielde nest, one of seven queens was removed and placed by herself
August 16 in a glass Petrie dish with moist earth, for special observa-
tion. She had broken off her wings the previous day. and was hence
presumably fertilized, altho she apparently had not left her native
nest. She began at once working in the earth as if to make a burrow.
This is the queen which killed a male placed with her, as described on
another page. She worked restlessly in the earth for several days,
helping herself to the sugar syrup offered her, and deposited six eggs
August 25. It is commonly supposed that a fertile queen does not
feed after leaving the family nest until she has reared workers capable
of supplying her with food. Possibly her nest was kept too dry and
the syrup was taken as drink rather than as food.

Another queen brought in from the field August 15, pulled off
three of her wings within the next two days, but did not succeed in
ridding herself of the fourth until August 25. This queen was re-
ported by Mr. Kelly to partake once or twice a day of the syrup placed
in her cell. She busied herself with piling up the dirt beside a bit of
wet sponge, sometimes undoing at one time what she had done at
another. She laid no eggs, and died September 6.

35

The significance of males in the ordinary life of the colony is
very small, and I have but few notes on their habits and behavior.
July 31 a worker, a male, and a pupa were placed together in a Petrie
dish, the pupa almost mature. This is a situation of great responsi-
bility for the worker ants, whose aid is necessary to the successful
emergence of the adult, and the single worker upon whom these labors
fell made every effort to discharge her duties alone, the male doing
nothing in her aid. The anxious and affectionate worker divided her
attentions between the helpless pupa and this idle male, caressing and
feeding him, and when, thru a misadventure, his wings were stuck to
the cover of the cell in the moisture which collected there, doing her
best to pull him loose. When the pupa was ready to yield the adult
the end of the pupa-case was bitten off by the worker ant; and its in-
mate pulled out head first in a helpless condition, unable even to stand.
In about three hours, however, it was walking about.

When the workers were moving the family from one cell of the
formicary to another, they were often seen dragging the males along
to the new quarters, as if ants of this stupid sex were unable to get
any idea of what was going on, and must be dealt with by physical .
force.

The responsibility of the workers for the successful transforma-
tion of the pupa and the appearance of the adult is well illustrated by
an observation recorded by Mr. Kelly under date of August 17. Ina
glass Petrie dish in which three workers and three pupz of the corn-
field ant had been placed for observation August 2, a worker emerged
from a pupa-case, two of the workers in the cell assisting. One of
these bit off the black tip of the pupa-case and slowly pulled the young
ant out, taking three minutes for the operation. The head of the new-
born worker was cleaned off and its antennze were straightened cut
by the mouth-parts of one of its nurses, while the other loosened and
straightened its legs. At the end of sixteen minutes from its release
it made its first attempts to walk. In this, as in other cases observed,
the workers. rewarded themselves by devouring the empty pupa-case.

The constant attention which the worker ants pay to their eggs
and larvze is so well known that it scarcely requires illustration. Many
of their ministrations, it is true, seem aimless and mechanical, mere
restless movements of their charges from place to place, but the con-
stant attention given by the workers to their young is an effective safe-
guard against any ordinary injury.

The eggs, deposited by the female, are gathered together by the
workers, kept in a pile or ball convenient of transportation in a mass,
and carried up and down in the nest according to the weather; and as
they hatch the young are separated from the mass of eggs and kept
by themselves, usually assorted according to size as they increase in
number and differ in age. Larve and pupz are likewise commonly
kept distinct, the various lots doubtless requiring somewhat different
care.

The workers feed their larvee almost constantly from the contents
of their own stomachs, and often mouth and hover them, a mass of

36

the ants clustering around and over them in a way to conceal them
from view. When the colony is established in a two-celled nest, one

covered with clear glass and the other with orange, the workers con-.

vey their young to the orange cell, the light transmitted by orange
glass being, as shown by Miss Fielde, inappreciable by ants.

Even after the workers have emerged from the pupa-case they
are still watched and cared for by their more experienced relatives,
and often fed in the nest by foragers returning from outside. This
operation was illustrated in our breeding-cages when pale young
workers remaining within the orange cell were fed by the darker,
older ones from food exposed to them in the light cell of the formicary.

The nursing instinct of the workers is so overruling that it ex-
tends to all the inmates of the nest excepting only strangers of their
own species. A common resident of the nest of these ants is a species
of mite (Macrocheles mestus Banks) often found crawling about
among the eggs and larve, altho never detected in any depredation
upon them. It is probably a scavenger of the domicil, and is thus
possibly entitled to the protection which it receives. When a nest con-
taining these mites is disturbed, they receive the same attention as its
other inmates from the alarmed and anxious workers. In several
nests for example, plowed up April 24, in an old oats field, mites were
commonly present, and the ants seized them in their mandibles and
carried them away as they did their own young.

ADAPTATION OF BEHAVIOR TO CHANGING CONDITIONS

The movements of ants in their outdoor habitations often show
a surprising adaptation of habit and behavior to changing conditions
in the field. It was repeatedly noticed, for example, that during warm
dry weather in early spring the aphis eggs would often be brought
near the surface while the larve of the ants were kept at a depth of
five or six inches below. The effect of this treatment must be to
hasten the hatching of the aphids and at the same time to retard the
development of the larve of the ants. The growth of the latter is thus
kept practically at a standstill while food is scarce in spring, but pro-
ceeds at a rapid pace after the aphids have hatched and are yielding
an abundant food supply to the colony. In periods of summer drouth
the burrows are extended downward to a depth of twelve or fifteen
inches, and eggs, larve, and pupz are carried down into relatively
moist earth. The ants then mass up in the depths of their burrows
and are rarely seen abroad, but communicate with their root-louse
herds by means of underground passageways, sometimes several feet
in length. When soaking rains come, these hidden colonies open up
their burrows to the surface again, as the ground dries off, and resume
their more active habits as general foragers.

Under certain conditions of serious deprivation and suffering
however, this whole system breaks down, and the ants may devour, for
their own temporary maintenance, the very objects to which they have
previously devoted their entire existence. When infested plants wither

ae

i VediNe

3/

and die, and no others can be found to which the aphids may be trans-
ferred, these are themselves eaten by the workers as a food material
too valuable to waste. When suffering from a lack of sufficient animal
food, the workers in our formicaries have occasionally helped them-
selves to a living pupa of their own species, or have even devoured
the larve in their charge, to the last one. The corn-field ant is, in fact,
essentially a carnivorous insect, and forages actively for animal food,
especially when it is without a sufficient number of root-lice. Much
of our breeding-cage work came to naught thru the mysterious death
of the workers, apparently because their liking for a watery syrup was
regarded as evidence that this was a sufficient food for them. In the
field and in the insectary we have seen ants feed at various times and
under various conditions upon cutworms, carabid larve, white-grubs,
dead May-beetles, dead beetles of the corn root-worm, dead grasshop-
pers, root-lice, myriapods, earthworms, their own pupz and larve, and
the pupal envelopes vacated by adults on transformation. Occasionaliy
they have been seen injuring corn by hollowing out the soft seed either
before or after sprouting, and in one case at least they were reported
by an insectary assistant as feeding on the fibrous roots of the plant.

AN INjJuRY TO CorRN BY ANTS

Under certain conditions, indeed, this corn-field ant may do con-
siderable injury to corn by a direct, unaided attack. During the cool,
wet spring of 1905, when the softened kernels lay long in the earth
without sprouting, and the young plants grew very slowly for a time,
a field of corn following oats, heavily infested by ants which had no
root-lice in their possession, was considerably damaged by the ants,
which gnawed and hollowed out the seed, thus either killing it, or so
diminishing the food reserve that the plant made a slow and feeble
start.

This field of forty acres, lying near Champaign, had been in oats
in 1904, in corn in 1903, and in grass in 1902. The corn was said by
the tenant to have been injured by root-lice in 1903, the part worst
infested yielding not over 22 bushels to the acre, while the remainder
of the field gave a yield of 55 to 60 bushels. Owing to a report that
the young corn was being injured by ants, Dr. J. W. Folsom, of the
University department of instruction, examined it for me May 31,
digging up sixty-one hills in a way to expose the whole root system.
Forty-one of these hills were in a part of the field but moderately in-
fested with ants, and thirteen were in an adjacent part in which ants
were very abundant. In both cases the hills examined were taken
as they came, one after the other in the row. Seven hills additional
were dug up here and there, because of an especially noticeable infesta-
tion. The corn in this field was unequal in condition, the poorer hills
being most numerous where ants were most abundant. This unthrifty
corn was four or five inches high, and of a yellowish hue, while the
better plants were six or seven inches high, and of a good green color.

In the less-infested row six hills out of forty-one were infested
by the corn-field ant, one of them containing also the red house-ant

38

(Solenopsis debilis). In five of the six infested hills a single kernel
of corn had been more or less eaten by the ants. No observations of
injury to the roots were reported, but the amount of stunted corn in
this part of the field could scarcely be accounted for except on the sup-
position that some other injury was being done than this to the kernel
in the hill. In the worse-infested part of the field thirteen hills were
examined, eleven of which were infested, and eight of them contained
kernels which had been more or less eaten by the ants. In five of the
hills all the kernels had been thus injured, and in the others only one
kernel to the hill. The ants in these hills were all the common corn-
field species except in one instance, where only Solenopsis was found.
In the seven hills selected because of their visible infestation, all the
kernels were eaten by ants in two, and a single kernel out of two or
three in each of the others, the ants in all these hills being the common
corn-field species. Rough estimates of the number of ants to a hill
ranged from ten workers as a minimum to a maximum of a thousand.
In one case only were ant larve present.

In all these sixty-one hills the corn root-aphis was found but four
times—twice a single winged female, once a winged female with three
large and thirty small wingless females, and once four winged females
with between forty and fifty wingless ones, nearly all of them young.
There were, in fact, more of the common grass root-louse (Schizoneura
panicola) in the field than of the corn root-aphis, some on the roots of
corn, with ants in charge, and others on smartweed and ragweed roots,
and also accompanied by ants.

From these observations we may infer that ants living in the
meadow-grass in 1902 with grass root-lice in their possession, infested
the corn the following year; that they continued in the field through
1904, when a crop of oats was raised, carrying a small percentage of
their grass root-lice over on roots of weeds in the field; and that when
the ground was planted to corn in 1905 they were still abundant there.
but with so few root-lice in their possession that they availed them-
selves of the softened corn kernels in the earth for food, probably
gnawing away, also, root hairs and the finer roots, as they have been
seen to do in confinement.

EFFECT OF A CHANGE OF CROP

The effect of a change of crop—from corn to oats, for example—
on the ant population of a badly infested field, was illustrated by an
account in my Thirteenth Report of the disappearance, during the
latter part of May, of both ants and aphids from an oats field formerly
in corn. By this time the weeds in the field were practically all dead,
the oats having reached a height to overshadow and sap them. A
similar occurrence, more closely observed, is reported by Mr. Kelly in
a series of notes running from April 21 to June 22, 1906. In a forty-
acre field of oats fifty nests of the corn-field ant were located and
marked near two sides of the field, one next a field of corn and the
other separated from corn by a hedge fence and a road. That this

39

field had been heavily infested by root-lice the preceding year was
shown by the number of aphis eggs and young aphids in possession of
the ants—the aphids on roots of smartweed and grasslike weeds in the
field. The ants themselves lived mainly under ground, at least by day,
rarely opening their burrows to the surface, until the 4th of May,
when, as the weather warmed up after a heavy rain, they made their
presence known by a deposit of pellets of earth at the surface around
the openings of their burrows. The oats at this time were about four
inches high, and smartweeds and ragweeds about half as tall. Both
the latter had many root-lice on them, but none were on the roots of
the oats, and the aphis eggs were not yet all hatched. Nests of the
ants were very abundant in the grass outside the borders of the field,
and several of these which were opened up contained corn root-aphids
on the roots of the grass. From the 8th to the 10th of May the ants
were actively running over the ground as if in search of food, but, so
far as could be seen, with meager result. The second generation of
aphids had by this time begun to appear, and many of the smartweeds
were dead at the root. The ground was very dry for the next few
days, and both grain and weeds grew very slowly, many of the oat
plants being dead. Thus matters went on, with no material change
except that the ants were found feeding freely on dead June-beetles
and other insects, until June 5, when it was noticed that the ants were
leaving the field.

“As I was returning home last evening,” says Mr. Kelly, “I no-
ticed crossing the lane beside this field a colony of Lasius miger ameri-
canus, composed of ants going in both directions between the field of
oats and the corn field on the opposite side of the road. I followed
the column thru a hedge fence and about twenty feet into the oats,
where they were coming out of their nest. Some of those going out-
ward were carrying larve, but none of those returning in the other
direction. The line of march was indirect, and about fifty-seven feet
long, ending in the grass on the opposite side of the road, where a
new nest was being formed. The colony was still moving at 6 the
following morning, evidently having been at work all night. They
had finished the transfer before 8 a. m., nothing remaining in the nest
from which they had emerged. No root-lice were in their possession,
but only their own larve.”

Finally, on the 22d of June, a thoro search was made of the sites
of all the nests marked as originally occupied by ants. Forty-nine of
the fifty were identified, the remaining one being lost. Forty-four of
these nests had been completely deserted, and only five were still in-
habited by ants. These were in rather open spots in the field, with an
abundance of grass about them. There were no corn root-lice on this
grass, however, but only the grass root-louse (Schizoneura panicola)
and a few Geoica squamosa. ‘The oats at this time reached about to
the knee, and were beginning to head.

From these data, combined with those previously published, we
may infer a gradual but general migration of the ants from the old

”

40

corn field, now in oats, to more favorable locations,—a migration which
included all the ants, of whatever age or condition, but in which their
aphid possessions were apparently sacrificed—probably eaten by their
owners. as a last resort of domestic economy. Not all the aphids of
the oats field were thus lost, however, but some seem to have been
transplanted to grasses near by, and others, which acquired wings as
food began to fail, escaped by flight, Such winged aphids were re-
peatedly seen to be captured by wandering ants, who took them in
charge and placed them on the roots of suitable plants. . Others, light-
ing by chance on a corn plant, made their own way down the stalk, and
thus found a lodgment on the roots, where they were doubtless after-
wards found and cared for by ants. Nevertheless, the loss of root-
lice consequent upon a change of crop, altho not complete, must have
been enormous, only now and then one of the aphis inhabitants of the
field being fortunate enough to fall upon favorable conditions; and
crop rotation remains one of the most effective means of checking the
multiplication of these destructive insects.

BEATE.

STAGES OF THE CoRN-Fie_tp Ant (Lasius niger americanus) ; worker; larva;
winged male; pupa; winged female; female with wings removed.

THE OPNSEC TT PESTS OF CLOVER AND
ALE ALPA

By J. W. FOLSOM, Assistant PROFESSOR OF ENTOMOLOGY,
UNIVERSITY OF ILLINOIS

INTRODUCTION

This account contains a large amount of new information on the
most injurious of the clover insects, and on some of the less important
species as well. Unless otherwise indicated, the observations were
made by the writer during three summers in which he was employed
by the State Entomologist, Dr. Stephen A. Forbes, for the special pur-
pose of studying these important insects.

The volume of the results obtained—many of them as yet unpub-
lished—is due in no small measure to the help of an assistant, especially
in the routine work of the insectary; and in this capacity there have
served at one time or another, Messrs. E. V. Bronson, E. O. G. Kelly,
R. L. Webster, and J. J. Davis. Their names appear later wherever
their personal observations have been used.

The present account contains not only new material, but also every-
thing of importance that has previously appeared in our literature of
the subject. The literature is large, but the greater part of it is a mass
of more or less useful repetition, which traces back to a few sources.
All the original articles are cited in the lists of references, as are also
the more useful of ‘the compiled articles. These references, tho not
voluminous, are comprehensive, and sufficient to guide one directly to
all the authentic sources of information on each subject treated.

Most of the illustrations were drawn for the State Entomologist
by Miss Charlotte M. Pinkerton, Mr. F. Knab, and Mr. W. C.
Matthews. Several electrotypes were obtained from the Bureau of
Entomology thru the courtesy of the Chief, Dr. L. O. Howard.

In the account that follows, consideration is given primarily to the
insect pests of red clover, and secondarily to those of mammoth clover,
white clover, alsike, and alfalfa. The last-named plant, introduced
into Illinois some ten years ago, is cultivated here and there in almost
every county, and has been adopted as a food plant by a large number
of the red-clover insects; but none of them have as yet injured it con-
spicuously, so far as the writer has been able to learn.

InyJURY TO CLOVER BY INSECTS

A field of red clover in full bloom is alive with insects. Such a
profusion of insect visitants, both as regards number of individuals and
number of species at one and the same time, is afforded by no other
plant that we know of, with the possible exception of alfalfa. In the

41

42

clover fields of the university farm we have taken two hundred species
of insects—not all of them injurious, tho more than half of them feed
on the plant. Adding to these the other species that have been listed
as feeding on clovers, vetches, and alfalfa, it is seen that these plants
are food for more than two hundred different kinds of insects. A
hundred more are predaceous or parasitic on these clover insects, or
else feed on animal or vegetable matter in the soil of the clover field.

No part of the plant escapes attack. The roots are eaten by the
larve and the beetles of the root-borer, as well as by those of half a
dozen other species, and are drained of their sap by the mealy bug.
The stem is hollowed out by the common stem-borer. Both the stems
and the leaves are pierced by many hemipterous insects, especially
aphids and jassids, and are eaten by a great variety of caterpillars,
beetles, and grasshoppers, as are also the heads of the flowers. The
ovule is destroyed by the maggot of the seed-midge, and the developing
seed is eaten out by the seed-chalcid. Even clover hay is the special
food of a certain caterpillar, hence called the clover hay-worm.

Some of the insects of the clover field are, of course, beneficial.
Such are those that pollenize the flowers,—bumblebees and, to some
extent, honey-bees,—as well as those that act as checks on the injurious
insects.

Most of the clover insects are not limited to clover, but have other
food plants as well. The seed-midge and the seed-caterpillar are, how-
ever, confined to the clovers, and the seed-chalcid to clovers and alfalfa,
so far as known. The root-borer is said to eat peas as well as clover.
The hay-worm has been found only on hay as yet, but the moth has
been raised from masses of dead grape leaves taken in a vineyard. The
leaf-weevil is reported from beans and timothy, as well as clover and
alfalfa. The clover-louse has been a pest of the worst kind on peas
and has a long list of food plants. Of the less important clover in-
sects, a few have no other food plant ; but the majority can easily main-
tain their existence when no clover is at hand.

In Illinois, where alfalfa is a recent introduction, its insects are
essentially the same as those of red clover, and it has as yet no insects
peculiar to itself. The leaf-weevil, seed-chalcid, and root-borer feed
on alfalfa, but not enough to have done any damage up to the present
time. Even the numerous caterpillars, beetles, and grasshoppers that
eat the foliage have not yet injured this newly introduced plant to any
great extent. An insect that eats a few alfalfa leaves is not necessarily
inflicting permanent injury upon the plant; for, up to a certain point,
the plant is injured by leaf-eating insects no more than a fruit tree is
injured by pruning. Red clover, also, is such a vigorous plant that it
easily withstands or repairs injuries of an ordinary kind. Thus in
April, 1907, 25 to 50 percent of the new leaves of red clover were
frozen and killed in this region, but the hay crop was as good as ever.
The temporary damage was far greater than that ordinarily inflicted
by the miscellaneous clover insects—leaving out of consideration the
seven pests named in the previous paragraph.

43

The combined efforts of all the insects, however, are sufficient to
reduce the hay crop materially every year. Aside from the occasional
conspicuous injury, there is every year a steady drain on the plant
thru the attacks of insects. This annual drain is not noticed for the
very reason that it occurs every year. If we could keep all the insects
out of the clover field, we should get more hay. If we could exclude
all except the bumblebees and the honey-bees, we should undoubtedly
get an immense increase in the yield of seed.

Those who raise clover seed on a commercial scale owe their suc-
cess to methods which operate chiefly against the insect enemies of the
seed—whether the growers are aware of it or not. Under the same
conditions of soil and climate, one man is able to get a good crop of
seed and his neighbor is not. The reasons for this are chiefly entomo-
logical, as appears in these pages.

THE FAILURE OF THE SEED CROP

Many farmers do not attempt to raise their own clover seed.
Those who do, get more or less of a crop according to circumstances.
Here in the black soil of the corn belt, 114 bushels of seed per acre is
about the average yield for red clover (Trifolium pratense) ; the soil
is not the best possible for clover; frequently too little seed is sown;
generally the oats and the wheat are regarded as of more importance
than the clover; and always the seed insects ravage the crop unless
certain precautions are taken. In DeKalb county the soil is better
adapted to clover, and, tho the winter conditions are now and then a
little severe for the plant, the farmer expects to get about five bushels
of seed to the acre by cutting the hay crop early. Under the most
favorable conditions, red clover has yielded eight bushels per acre; I
have found records of nine, but the more authentic accounts name no
more than eight.

Many influences, more or less important, combine to reduce the
crop of seed. Adverse mechanical or chemical conditions of the soil,
or unfavorable conditions of the weather, may prevent the plant from
flowering properly. With good conditions of soil and weather, the gen-
eral health of the plant may be impaired by fungous diseases of several
kinds or by insects, particularly the root-borer, the leaf-weevil, and the
clover-louse; their devastations cause the heads to flower unevenly and
imperfectly, and prevent the formation of a large number of heads in
the crop directly attacked by them.

These injuries, due to influences that affect primarily the general
health of the plant and secondarily the seed, are easily referable to
their respective causes. The worst injuries to the seed are more in-
sidious in their nature, and are caused by insects. These injuries are
of three classes: (1) those of a negative kind, due to lack of pollina-
tion; (2) the positive injuries due to miscellaneous insects that eat
clover heads in an incidental way; (3) the positive injuries caused by
insects that feed solely upon clover seeds or florets. The first two
groups are relatively unimportant in comparison with the last.

44

1. We should have no red clover seed at all were it not for the
operations of the bumblebees and, secondarily, of the longer-tongued
honey-bees (those of Italian races), for red clover is incapable of self-
pollination. The importance of the bumblebee in the pollination of red
clover is so well established as to need no discussion. - That of the
honey-bee, however, is not sufficiently recognized. The honey-bee pol-
lenizes red clover to some extent, even tho its tongue is two millimeters
shorter than the average corolla tube. A field of red clover is always
thronged with honey-bees if any of them are being kept within a mile
or two of the place; and these bees secure nectar from flowers that are
undersized, especially in times of drought, when most of the flowers
are smaller than usual; also from flowers that secrete a copious amount
of nectar. Furthermore, the honey-bees, in their attempts to get the
nectar, go thru the motions of pollination whether they get any nectar
or not, as I have ascertained.

The lack of seed in the June or early July crop is generally at-
tributed to the lack of bumblebees at that time, and rightly so, in my
opinion. Occasionally, however, the farmer is surprised to find a pay-
ing amount of seed in his first crop. This happened in Illinois in 1906
and again in 1907 in various counties in all parts of the state, as I have
learned from correspondence and from personal conversation with
clover growers at the State Farmers’ Institute and elsewhere. This
early seed ran one to two bushels to the acre; some of it was put on
the market in Quincy, Ill. Only two farmers offered any explanation
for the production of clover seed at this untimely season, and they laid
it to a “miller” that pollenized the flowers by night unobserved. This
miller I am not acquainted with; perhaps the honey-bees pollenized the
flowers.

Ordinarily, however, we do not expect to get seed from the June
crop; and by midsummer there are always enough bees to pollenize the
flowers. The failure of the seed crop need not be laid to lack of pol-
lination as yet. In the future, if bumblebees are constantly destroyed
we may be obliged to cultivate them artificially—and this can be done,
if necessary for the welfare of clover. The indiscriminate killing of
bumblebees should be stopped. They are the best friends of the clover
grower.

2. The seed crop is diminished to some extent by various grass-
hoppers, beetles, and caterpillars that eat the blossoms here and
there, and sometimes the green seeds. They prevent pollination and
destroy developing seeds in some measure, but can scarcely be guarded
against, and need no special consideration.

3. There are, however, three insects that must be guarded against
if one wishes to raise a good crop of seed. These are the seed-midge,
the seed-chalcid, and the seed-caterpillar. When clover blooms well,
and there is good weather, the failure of the seed crop is to be charged
to these three insects, the last of them being the least to blame, as a
rule. All three can be controlled by simple methods described later,
the most important of these being the early cutting of the hay crop.

45

It seems curious at first sight that an unusually large yield of
seed should follow the ravages of the clover leaf-weevil. Yet this has
occurred in several instances. Webster observed the fact in Ohio. The
explanation is simple, however, in my opinion, for the weevil, when a
pest, consumes enough leaf tissue to delay the growth of the plant
materially, taking the seed crop out of the reach of its worst insect
enemies. The result is the same as that obtained by the seed growers
who pasture the clover in May or early June.

Early pasturing or cutting is the secret of a good seed crop, as the
growers in New York, Ohio, Michigan, Canada, and elsewhere have
found. The reason for the practice is not universally known, however,
as is evident from the inadequate explanations that have appeared now
and then in agricultural publications. For example, Shaw says (Clo-
vers, etc., p. 103), “Experience has shown, further, that, as a rule, bet-
ter crops of clover seed may be obtained from clover that has been
pastured off than from that which has been mown for hay, although to
this rule there are some exceptions. This arises, in part, from the
fact that the energies of the plant have been less drawn upon in pro-
ducing growth, and, therefore, can produce superior seed heads and
seed, and in part from the further fact that there is usually more
moisture in the soil at the season when the plants which have been
pastured off are growing. There would seem to be some relation be-
tween the growing of good crops of clover seed and pasturing the
same with sheep.” The fact is that pasturing gives a good seed crop
for the reason that it delays the heading of the plant until a time when
the seed-midges and seed-chalcids are no longer on the wing and laying
eggs. When precautions are not taken against these pests, they can be
counted upon every year to destroy most of the clover seed. In this
region the midge and the chalcid eat from 50 to 75 percent of the red-
clover seed every year without hindrance. The farmer gets only
what the insects leave. If he gets two bushels of seed to the acre, the
insects have already eaten from two to six bushels off the same acre.

CoNTROL OF CLOVER INSECTS

The insect pests of clovers are but seven, and they are within our
control if we choose to control them. Moreover, they can be controlled
by means that interfere little, if any, with usual farm practice; and the
methods of control do not conflict with one another, but are essentially
the same for all the clover pests,—referring especially to those of red
clover.

The worst of these to deal with, where it occurs injuriously, is the
root-borer. If it is very destructive in spring, plow the clover under,
for this insect has quite its own way. The other pests can be disposed
of without sacrificing the plant.

If the hay crop is threatened seriously in spring by the leaf-weevil
or the clover-louse, pasture it or clip it back in May; otherwise, cut
the hay as early as possible, in order to insure a good second growth.
Usually, however, these two insects are subdued by natural agencies,
in spite of their abundance.

46

To get rid of the worst of the seed insects, pasture or clip back in
May or early June; or else cut the hay as soon as possible—as soon as
it is fresh in bloom, or earlier.

Cut red clover, or pasture it lightly, in the latter part of the first
season, as this goes far to reduce the number of insect pests in the
same field the second year, and does not injure the clover if done
intelligently. Destroy volunteer clover, which is a rich nursery for all
kinds of clover insects. It can be cut most conveniently with the rest
of the clover—twice a year.

Do not permit red clover to run for more than two years in this
region, where it is, for agricultural purposes, a biennial.

CLOVER SEED-MIDGE
Dasyneura leguminicola Lint.
(Cecidomyia leguminicola)

This widely distributed pest, abundant in clover fields, prevents
the formation of seed. At the titne of blossoming, the florets affected
by this insect remain for the most part green and undeveloped, and
their ovaries are hollowed out and empty, or else contain each a small
orange, pink, or whitish maggot. Having entered the flower-bud, the
maggot consumes the fluid contents of the ovary before the bud has a
chance to open. Hence the term bud-midge would be even more ap-
propriate for this insect than that of fower-midge—recently proposed
by Webster.

The maggots develop into delicate little red-bodied flies, which are
so small as easily to escape observation, altho they are very abundant
in clover fields at certain periods of the year.

Distribution.—The clover seed-midge has been reported as de-
structive in Vermont, New York, New Jersey, Pennsylvania, Delaware,
the District of Columbia, Virginia, Ohio, Illinois, Iowa, Michigan, Wis-
consin, and Nebraska, and doubtless occurs in other states in which
clovers are grown. It does great damage in the province of Ontario,
Canada, and, according to Miss Ormerod, is also found in England.
In Illinois, the pest was observed as long ago as 1878 or 1879 (Fif-
teenth Rep. State Ent: Til., p. 3).

Food Plants—tThe chief food plant of the species is red clover,
but white clover also is affected. The published statement that alsike
clover is exempt from attack is incorrect, the writer having reared the
midge from alsike. This clover is not badly infested, however, proba-
bly because it forms its heads three weeks later than red clover, at a
time when there are but few seed-midges on the wing. For the same
reason mammoth clover ought to escape severe attack, and such is said
by one writer to be the case (/nsect Life, Vol. V., p. 74). An implica-
tion to the contrary, however, is found in another publication (Bull.
116, Mich. Agr. Exper. Station, p.55). I have had no personal experi-
ence with the midge on mammoth clover, but would point out the pos-

47

sibility that the injury in Michigan was done by the seed-chalcid rather
than by the seed-midge.

Alfalfa is not yet known to be a food plant of this insect.

Descriptions —The egg is barely visible to the naked eye. It is
elliptico-cylindrical in form, at most 0.3 mm. long and 0.075 mm. broad,
with the shell smooth and transparent. The color is at first a uniform
watery yellow, but soon an internal orange spot appears, and finally
the egg becomes orange thruout.

The larva (PI. IL., Fig. 1) is a footless maggot, orange-red, pink, or
almost white, 2.3 mm. long and one third as broad, when full grown,
with the surface of the skin minutely granulate. It has thirteen seg-
ments behind the head, and, like other cecidomytid larve, bears nine
pairs of respiratory tubercles, situated respectively on segment 2 and
segments 5 to 12 inclusive. All these tubercles are lateral in position
excepting the first and the last pairs, which are dorsal and posterior on
their respective segments. A peculiar organ known as the sternal
Spatula may be detected lying against the ventral face of segment 2,
and the form of this organ (PI. I1., Fig. 2), while subject to some varia-
tion, is sufficiently characteristic to distinguish this larva from that of
the clover leaf-midge, the only other insect with which it is likely to
be confused.

The cocoon, made by the larva, is oval in form, 2 mm. long, and
composed of silken threads. It is difficult to find out-of-doors owing
to its being covered with particles of dirt. The pupa, described in
some detail by Comstock, is pale orange, with brown eyes, a pair of
short conical tubercles on the front of the head, and a rather long horn
near the base of each wing; the antennal sheaths of the cast pupal
skin curve outward like the handles of an urn.

The appearance of the female midge is well shown in Figure 3,
Plate I]. When on the wing, she is nothing but a filmy speck, that
easily eludes the vision. After alighting, her red abdomen and long
threadlike legs catch the eye. Under the microscope, the head is seen
to be black, and the antennz yellowish red, with sixteen—or even sev-
enteen—sessile segments. The sides of the thorax are reddish brown;
above, most of the thorax is black, but two small posterior lobes are
brownish red; the halteres are reddish yellow. The wings are trans-
parent, closely set with short, curved, dusky hairs, and strongly fringed
posteriorly with long paler hairs. Legs slender, reddish brown, the
segments becoming darker distally. The abdominal segments 1 to 6
are salmon-red above, mixed with yellowish beneath; dorsally each of
these segments is banded with black scalelike hairs, which rub off
easily. Segments 7 to 10 of the abdomen form the pale yellow
Ovipositor. The insect, with ovipositor retracted, is 1.8 to 2 mm. in
length, and with the ovipositor extruded, 6.2 mm. The antennz are
0.8 mm. in length.

The male resembles the female, but bears a pair of conspicuous
clasping organs at the end of the abdomen and has but fifteen antennal
segments, all but the first two of which are pediceled.

48

We have no other midge that I know of in a red clover field that
may be mistaken for the seed-midge, tho in Europe the leaf-midge was
originally described from red clover. Both midges affect white clover,
however, but can be distinguished by the characters given on page 100.

Life History—In central Illinois, the clover seed-midge winters
as a full-grown larva, or as a pupa, in the soil of the clover field or in
dead clover heads. A few warm days and a little rain bring the larve
to the surface of the ground a few days after the red clover has
started on its second year’s growth. Thus in 1907, in Urbana, the
first new leaves of red clover appeared March 19—a little earlier than
tisual—and the orange-colored larve of the midge were found on the
ground from March 25 to April 4, inclusive, being most numerous
March 30 and April 2. They are by no means abundant, however, at
this time in a clover field of the second year, and would not be present
at all but for the precocious development of some clover heads during
the preceding season. Some of these larvae make a cocoon and some
do not. In either event the larva contracts in length and its integument
hardens and becomes duller in color, forming a puparium, within which
the pupa develops. One larva, found March 25, 1907, made a cocoon
March 30, from which a female midge emerged April 12 or 13. A
second larva, taken March 30, formed a cocoon April 2 and gave a
female fly April 21. Both of these flies were reared indoors, it should
be said. Out-of-doors, midges were not found until May 15, but were
common May 23 (at which date oviposition was in progress) and at-
tained their maximum numbers May 30. This season was a late one,
however, owing to continuous cold weather in April, and in the years
1903 to 1906 inclusive the dates of maximum abundance were May 24
and 25, the time when young green clover heads also were most numer-
ous. The larve work in the heads during June and the first week of July,
and leave the heads when full grown and go to the ground to pupate.
Our earliest date for the emergence of larve from the heads is June 20.
Most of the larve emerge about June 30, tho not a few wait as late as
July 8. The pupal period at this time is three weeks or more, and the
flies of the second generation are most abundant in the last week of
July and the first two weeks of August, tho scattering individuals
emerge at almost any other time between the middle of July and the
first of September. The egg period in early August is three days,
varying a few hours, more or less, according to temperature. Most of
the damage to the seed crop is done during the last two weeks of Au-
gust and the first two weeks of September, when the larve are most
numerous in clover heads. Most of these larve pass the winter as
larve or pup, to emerge as flies the following May. A few larve,
however, attain their growth early enough to produce flies in early Sep-
tember or even later, out-of-doors. Under the sheltered conditions of
the insectary, but without artificial heat, flies appeared as late as Octo-
ber 10; and in a warm room flies will emerge from clover sod thruout
the winter. It appears that the few flies of late September do not
succeed in propagating their kind in this latitude, owing to the direct

49

effect of frost on the flies, but especially to the death of green clover
heads before any larve therein can attain their growth. It is possible,
however, that flies of early September produce larve capable of sur-
viving the winter.

Thus there are in central Illinois two full broods of the seed-
midge each year and a feeble third generation of flies, which belong
essentially to the May brood of the next year. In the literature we
find that maggots of the seed-midge emerged in immense numbers
from clover heads in Washington, D.C., on May 23, 1880. This date
would be one month too early for such an occurrence in this part of
Illinois, where May 23 is ordinarily the time of maximum abundance
of the first generation of flies.

Habits—tThe eggs are laid always in green flower-heads, and
chiefly during the warmer part of the day.. With the aid of a hand
lens, the process of oviposition can be observed, the female being fre-
* quently too busy to pay any attention to slight interruptions. The last
four segments of the abdomen of the female are elongate like a tele-
scope, forming a slender tapering ovipositor, twice as long as the re-
mainder of the body and as flexible as a whip-lash. Standing on the
outside of a green clover-head, the female inserts this organ among
the florets and works it deeper and deeper until it can go no farther.
The sensitive tip of the sinuous ovipositor finds a suitable spot for an
egg and the female becomes quiet until the egg is laid. The entire
process of egg-laying requires usually five minutes, and often ten to
fifteen minutes. Tho the same female may lay several eggs in one
clover head, she appears to make it a rule to distribute her eggs among
a good many plants. Many females may, of course, oviposit in the
same head, with the result sometimes that more larvze -hatch than
can possibly find food. Thus in one head of eighty florets the writer
found 106 eggs. Once in a while an egg is laid on a petal or on the
calyx itself, but almost always it is glued to one of the hairs of the
immature calyx, the glue often forming quite a perceptible mass. This
is contrary to a published statement that the eggs “do not appear to
be glued to the hairs.”

The newly hatched larva has only one way of entering the ovary
of a flower, namely, by squeezing in between the unopened petals, as
Comstock said. Once inside the flower-bud, the maggot, incapable of
biting any solid substance, sucks the fluid contents of the ovary, de-
stroying the ovule or ovules. An affected floret presents externally
a healthy appearance but the petals do not expand, except rarely.
They remain fresh and pink until after the maggot leaves the bud, but
eventually fade and wither away without opening.

The simplest way to get specimens of these larve is to collect
clover heads that are partly green and partly in bloom, and to shake
them up a little, when many of the larve will squirm their way out of
the buds. The maggots often occur in great numbers on the bed of a
hay wagon or the floor of a barn. Ina tight glass jar of clover heads
all the larve present will emerge, and the precise amount of infestation
can be ascertained. :

50

Tho the full-grown larve may simply drop to the ground, as other
writers have stated, they frequently wriggle their way down along the
stem of the plant, when the latter is wet with rain. Indeed, the larve,
even when full grown, will not emerge if the air is too dry. Ceci-
domyiid larve in general require considerable moisture for their de-
velopment and are very sensitive to the influence of humidity. Dry-
ness causes the seed-midge larve, when on the ground, to squeeze
themselves into crevices in the soil and to contract the body and become
motionless, as 1f for pupation. Even then, however, moisture will re-
peatedly revive them to a condition of wriggling activity.

The period of pupation is lengthened by dryness and shortened by
moisture. Prolonged dryness kills both larve and pupz. Out-of-doors
the flies do not emerge during a dry spell; continuous dry weather
will delay their appearance as much as two weeks; but they may be
expected to appear after a rain, in the appropriate part of the season.
In the insectary, the emergence of the flies can be similarly controlled
by moisture, as G. C. Davis has already noted.

Riley states that the pupa works itself thru its cocoon and to the
surface of the ground when about to give forth the fly.

Autumn finds larve of various sizes in the clover heads, in central
Illinois. Most of the larve become full grown and go to the ground
in September; the rest remain in the heads and either finish their growth
or else succumb to frost. In spite of frosts, full-sized larva may be
found in the heads as late as the middle of October. October 28, 1907,
we found in clover heads several larvee which were so small (0.8 mm.
in length) that they must have been derived from late September flies,
and they were altogether too small to survive the imminent death of
their food plant.

The recognized injury done by the seed-midge to red clover occurs
during the second year of the plant, and the amount of injury increases
the longer the plant is allowed to run.

Vigorous plants, however, form heads during their first year, and
in these premature heads not a few larvze of the seed-midge are to be
found in autumn.

Natural Enemies—tThe chalcid, Bruchophagus (Eurytoma) fune-
bris How., at first suspected of being parasitic upon the larva of the
seed-midge, is now known to destroy the seed instead of the larva,
taking what the seed-midge leaves.

We have reared from clover heads containing larve of the seed-
midge two as yet undetermined species of the chalcid genus Tetrasti-
chus. These are possibly the same two that are mentioned by Webster
as having been reared directly from both larve and pupz obtained
about Lincoln, Neb., in December. In Delaware, Sanderson bred from
larve of the seed-midge, in October, 1899, and in June, 1900, parasites
determined by Ashmead as Tetrastichus carinatus Forbes and Torymus.

Another parasite of the seed-midge is Anopedias error Fitch, of
the family Platygasteride, a minute black species, about which almost
nothing has been written since Comstock, in 1880, reported it as emerg-
ing from the cocoon of the clover seed-midge.

Sit

An energetic enemy of the seed-midge is the common flower-bug,
(Triphleps insidiosus Say), as was found some years ago by Dr.
Forbes. I have repeatedly found a nymph or an adult of this bug with
its beak thrust into a seed-midge larva or fly.

Control—It is by no means necessary to abandon temporarily the
raising of clover seed on account of this insect, as was once proposed.
The most effective and most practicable preventive is that given by
Comstock, namely, to cut the first crop of clover as early as possible,
in order to secure a good seed crop at the expense of a slight reduction
in the hay crop. The good results of this method are frequently ob-
tained, unconsciously, by farmers who make it a rule to cut their clover
near the 17th of June. The writer was once sent by our State Ento-
mologist to examine injured clover on the farm of A. E. Myers, at
Millbrook, Ill. (Kendall Co.). At that place, August 19, 1903, there
were twenty acres of red clover in full bloom, with the heads well filled
with sound seed, with few green heads, and with almost no sign of the
seed-midge; no eggs were found and only two midges were seen dur-
ing an extensive search. This clover had been cut a few days before
June 25. Across the road was another field of red clover, similar in
history to the first except that it had not been cut until between July
4 and 10. Here none of the clover was in bloom, all the heads were
green, and almost every head was loaded with eggs of the seed-midge ;
often there were more eggs in a head than there were florets. The
flies were abundant also, and were still ovipositing. In this instance,
a difference of two weeks in the time of cutting meant all the difference
between almost complete immunity and heavy infestation.

Early cutting (1) results in the drying up of the food plant and
the undeveloped larva, and (2) hastens the development of the second
lot of clover heads, so that the midges of the second generation find
but few green heads in which to lay their eggs.

The proper date for early cutting depends, of course, on latitude,
weather, and other considerations. It should be not later than June 17
in central Illinois, and need not be earlier than June 7. Clover that is
cut too green does not cure well, but the cutting need not be done until
the field as a whole is fresh with bloom, tho it should not be delayed
until the flowers have withered. A clover head half red and half
green means that the seed-midge is present (or else the seed-cater-
pillar), and the grower who will take the trouble to study the habits of
the midge will be able to cut his clover at just the right time to get rid
of the seed-midge without losing much of his hay crop.

Similar results may be had by mowing back the clover as early as
the middle of May, in Illinois and Ohio. This delays the heading
enough to escape the second brood of flies.

Pasturing in spring and early summer exterminates the midge and
yet insures a good crop of seed, so far as this insect is concerned. This
method, as recommended by Dr. Fletcher, has been adopted with great
success in Ontario, Can. There the first crop is pastured to cattle or
sheep until the beginning of June but not later than the middle of that

Sf

month. In Michigan, also, the same method is successfully employed -

by dairymen, the clover fields being pastured until the 10th or 15th of
June42(G. C.Davis:)

Contrary to what might be anticipated, the seed-midge neither flies
far nor is carried far or in large numbers by the wind. Most of the
midges that emerge in a clover field stay there and lay their eggs there.
If the wind blows they cling to the clover plants or to the ground, or
take but short and occasional flights. The direction of flight is, to be
sure, determined by the wind if the wind is strong, and the midges are
certainly disseminated more extensively by the wind than by their own
powers of flight. Nevertheless, the number of midges carried from
one field to another by the wind is, in the experience of the writer,
comparatively small. For example, most of the midges in a given
field of second-year clover on May 25 came forth in that field and
were the offspring of the few midges that entered the same field during
the latter part of the preceding year. Hence it would seem to be a
wise procedure to prevent the sporadic heading of first-year clover by
mowing it back a few weeks after the oats (or other small grains)
have been harvested, at a time when the growth is vigorous, but yet
sufficiently early to permit considerable further growth before frost
sets in. This cutting need not injure the clover. In this state, red
clover is not infrequently cut in the latter part of the first season, for
a light hay crop, or to prevent premature seeding, and in the good
growing season of 1907, some first-year clover hay (mixed with stub-
ble) was put on the market. This cutting impairs neither the hay
crop nor the seed crop of the ensuing year, provided it is done early
enough to allow the plants to recover before winter. Volunteer clover
should always be cut, as it affords a rich nursery for all kinds of clover
insects. ;

Where clover and timothy are mixed, early June cutting will,
in this latitude, sacrifice the timothy. To obviate this, pasture lightly
or clip back the growth in May. This treatment, as Webster states,
brings both the first and the second blooming of the clover too late for
the destructive work of the midge, and the hay crop as a whole sus-
tains no loss.

In a few reported instances, larve of the seed-midge have been
found mixed with clover seed in bulk, and the theoretical danger of
sowing such larve along with the seed has been pointed out. While
we have no direct evidence as to the reality of this danger, it would be
well, on general principles, to kill such larve, by drying them up under
a gentle heat, which is said not to injure the seed, or by fumigation
with bisulfid of carbon.

Dasyneura leguminicola Lint.
1879. Lintner, J. A——Can. Ent., Vol. XI., pp. 44, 45, 121-124.
Riley, C. V.—Rep. Comm. Agr., 1878, pp. 250-252.
1880. Comstock, J. H—Rep. Comm. Agr., 1879, pp. 193-197.
Lintner, J. A.—Thirty-ninth Rep. N. Y. State Agr. Soc.,
1879, pp. 37-41.

owt

fs)

Lintner, J. A——Rep. Ent. Soc. Ontario, 1879, pp. 28-30.
1881. Lintner, J. A—Fortieth Rep. N. Y. State Agr. Soc., 1880,
pp. 20-24. Separate, pp. 11-15.
1882. Saunders, W.—Rep. Ent. Soc. Ontario, 1881, pp. 38-43.
1885. Fletcher, J—Rep. Ent. Dept. Agr——. Separate, pp.
1213;

1891. Ormerod, E. A—Fourteenth Rep. Inj. Ins., pp. 23-27.
1894. Davis, G. C—Bull. No. 116, Mich. Agr. Exper. Sta., pp.

52-56.

1899. Hunter, W. D—Ann. Rep. Neb. State Bd. Agr., 1898, pp.
247-249.

1906. Webster, F. M.—Circ. No. 69, U. S. Dept. Agr., Bur. Ent.,
pp. 3-7.

CLOVER SEED-CHALCID

Bruchophagus funebris How.

This abundant and energetic chalcid, formerly presumed to be an
enemy of the clover seed-midge, is now known to be itself one of the
worst of the clover pests. Instead of being parasitic, like most of the
chalcids, it eats out the clover seeds and reduces the seed crop ma-
terially.

The adults—little, compact, black, flylike insects—are common on
clover heads that are fading and ripening. Seeds containing the larve
of this chalcid become brown, brittle, and hollow, and when the clover
is threshed, the empty shells left by the adults are swept away with
the chaff.

Not until. 1896 was this ubiquitous insect suspected of being a
clover pest, and up to the present time its life history and habits have
remained almost a blank, except for what E. S. G. Titus has written.
The present account makes considerable additions to the knowledge
of the subject.

Distribution—Vermont, Rhode Island, New York, Delaware, Dis-
trict of Columbia, Virginia, West Virginia, Ohio, Indiana, Illinois,
Michigan, Kansas, Mississippi, Minnesota, Colorado, California, Ore-
gon, and Washington. Most of these records are from Titus, who
reared the insect from clover heads obtained from various states.

Food Plants—Red clover is the chief food plant, tho crimson
clover is badly affected, according to Hopkins. Alfalfa is another food
plant, but one of minor importance in my experience. I have not
found the chalcid on white clover, but have seen the adults on mam-
moth clover.

Injury —lIt was A. D. Hopkins who found that this chalcid eats
the seed, instead of being a parasite upon some insect.

The larva requires a seed that is going to grow, and this need is
provided for by the egg-laying habits of the female. She does not lay
her eggs in green heads, but selects, primarily, heads that have just

54

begun to wither, and, secondarily, heads that are in full bloom. Some-
times I have seen her trying in vain to thrust her ovipositor into a seed
that had hardened. The young larva feeds upon the semifluid albumen
of the cotyledons of the seed; as the seed hardens, the jaws of the
larva harden also, and at length the larva has eaten out the interior of
the seed, leaving only a thin shell. Externally, an affected seed looks
unhealthy. Instead of being blue, or clear yellow tinged with red or
purple at the end, and plump, it is dull brown, often misshapen and a
little undersized. At threshing time some of the adults have issued,
leaving only the shells of the seeds, and these shells blow away, making
an unaccountable shortage in the yield; other seeds, that still contain
the insect, may remain behind with the sound seeds, but are of course
good for nothing. These seeds that contain the insect are not neces-
sarily so light that they blow off with the chaff, as one writer has
assumed; many of them, if not most of them, are heavy enough to
stay with the sound seeds, as I have often found. The empty shells
are swept away. From newly threshed seed the adults may continue
to emerge in swarms, as R. H. Pettit noticed. Thus the yield of seed
is reduced in amount, and part of the yield made valueless, by this
insect.
August 1 we examined 49 seeds taken at random, and found 35
to be sound and 14 to be Tea et by the chalcid; of the latter, 3 were
: empty, 6 contained each a
larva, 4 a pupa, and 1 an
adult. Titus has found
seed injured to the extent
of 40 to 85 percent, with
an average of 50 percent to
the head.

Without examining the
seeds there is no way of
telling whether the chalcid
is present or not, for the
rest of the plant shows no

Fic. 1.—Clover Seed-chalcid, Bruchophagus funebris; indication of the presence
adult female. (Webster, Circ. 69, Bur. Ent., U.S. of the pest.

Dept. of Agriculture.) Stages.—The adult (Fig.
1) is a minute, compact, flylike insect, mostly black, but with parts of
the legs yellowish brown. It is small—the female being 1.9 mm. in
length and the male 1.7 mm.—yet its actions on a clover head are so
characteristic that one who has made the acquaintance of the insect
can recognize it at once. Apart from its natural surroundings, how-
ever, one must look to certain minute details of structure in order to
determine the species.

In the genus Bruchophagus the marginal vein is linear and not
longer than the stigmal vein; the mesonotum is umbilicately punctate,
and the abdomen ovate, pointed, and compressed in the female. The
male resembles the female but lacks the point to the abdomen, and the

55

abdomen is shorter than in the other sex; while the male, unlike the
female, has oval funicle segments and long antennal hairs.

The male of this particular species, funebris, is black and non-
metallic. Eyes dark brown, antennze almost as long as the thorax;
flagellum of eight segments, there being five in the funicle and three in
the club; the funicle segments have each a short apical peduncle, and
all but the first of these segments have either two or three whorls of
yellowish hairs—usually three on the second segment of the funicle
and two on segments three to five. The knees, anterior tibia, and all
the tarsi are light yellowish brown. The stigma of the wing gives off
a feeble branch. The abdomen, joined to the thorax by a short, stout
peduncle, is small, being less than half as long as the thorax, and its
fourth segment is the largest.

The female is like the male in coloration but is larger, with these
distinctive characters. Antennal segments not petiolate, and without
the long hairs; flagellum of nine segments, the funicle having six and

the club three. Abdomen not pedunculate,
longer than the thorax, with the fourth and
fifth segments short and subequal, and with a
light brown pointed extremity—a part of the

ovipositor.
3 S
\
\ Fie. 3. Fie. 4.
Fie. 2.—Clover Seed-chalcid, Clover Seed-chalcid, Bruchophagus funebris: Fig. 3, larva,
Bruchophagus funebrts, and head at right; Fig. 4, pupa. (Webster, Circ. 69, Bur.
eggs. Greatly enlarged. Ent., U.S. Dept. of Agriculture.)

The egg (Fig. 2) is broadly elliptical to ovate in form, ending
anteriorly in a small papilla and prolonged posteriorly as a slender
tube, at least twice as long as the egg proper, which averages 0.26 mm.
in length. The egg when laid is translucent whitish, and smooth;
within a day, the appendage shrinks and turns brown.

The maggotlike larva (Fig. 3) is white, stout, and footless, with a
small head; length, when full grown, 1.5 to 2 mm. The larva shows
few distinctive characters, tho it is stouter and less active than para-
sitic larvee of the same family.

The pupa (Fig. 4) is for a time white, but darkens as the color
of the imago develops; length 1.9 mm.

Life History—In 1904 and 1905 we made daily observations on
the number of adults emerging from clover heads collected thruout the
season and kept in large glass jars—each lot having been collected at
one time and place. The observations when plotted on coordinate
paper showed several new things.

56

Beginning April 14, there was a gradual increase in the number
of emergences up to June 6 and 12; then a rapid decrease to July 6;
afterward a sudden rise from August 4 to a high maximum August 10,
followed by a rapid drop to August 24, after which date adults issued
constantly, but in moderate numbers, until October 15. Out-of-doors
the adults do not begin to emerge until about May 15, as a rule, and in
1907 no adults were seen until May 23, tho the clover fields had been
searched almost every day for them. The June and August dates of
maximum emergence in the insectary agreed with the dates of maxi-
mum abundance in the field. One year, however, I found the chalcids
common July 6 to 19, and very common about July 15, tho in most
years there are but two times of greatest abundance, and these are when
faded clover blossoms are most numerous in the fields of cultivated
clover. Some adults can be found, however, almost any day in the
season from May 15 to October 15, or later, especially on volunteer
clover, where they can always find heads in just the right condition for
oviposition.

The insect passes the winter inside the seed, on the ground. The
seeds that we have collected and examined in early March contained
larvee only; in late autumn the seeds taken from dead clover heads on
the ground contained many larve and now and then a pupa. Evidently
the species winters chiefly, if not almost entirely, as a larva, in this
region.

As the first period of egg-laying extends over a month or more,
there is a corresponding range in the time of emergence of the second
lot of adults. Thus, clover heads collected June 18 gave adults June
21 and every day from July 4 to July 20.

More than this, there occurs a surprising extension of the period
of emergence. For example, heads collected June 21, 1904 (Urbana,
Iil.), gave adults June 24; July 2, 4, 5,6; August 9, 10, 11,12, 13;
then no more until the next year, 1905, when more adults issued May
27, 30, and June 5. Thus the last adults appeared almost a year later
than the first ones—all these from eggs laid inside a period of one
month. One to nine individuals issued on each of these dates, and the
majority issued during the first year.

Compare this record with the above: Heads collected June 28,
1904 (De Kalb Co., Ill.) gave adults (in Urbana) July 2 (5 individu-
als) ; August 8 (1), 12 (4), 15 (1), 19 (1), and no more until 1905;
then adults issued: May 30 (2)),-o1 (2) s2Jame gt). 202, oasis 5
(11), 6 (24), 7 (8), 8 (3), 9 (9), 10 (4), 12 (35), 13 (10), 14 (12),
15 (18), 16 (8), 17 (8), 19 (7), 20 (2), 22 (2), 24 (2), and none
thereafter. Here, the great majority failed to emerge until the follow-
ing year. Usually it is the other way.

By July 15 or a little earlier, new eggs begin to be laid in the new
growth of red clover—the seed crop. We collected an immense num-
ber of clover heads July 28, 1904, which gave adults as follows: Au-
gust 5 (many), 7 and 8 (194 individuals), 9 (42), 10 and 11 (13), 12
(103), 13 (23), 14.(6), 15-31), A666) 2) 1840) ee

Lea

57

(8) ; then no more until 1905, when a few issued May 24 (2), 29 (3),
June 5 (1), 7 (1) ; then no more—observations ceasing August 8. In
this case, the majority emerged near the middle of August and the
minority waited until the next year.

Taking heads collected still later in the season—August 26, 1904—
these gave imagines August 30 (a few), 31 (a few), September 1
ffew);, 2 (few), 4, 5, 6, 7 Se lea On LZ S19) 2002125.
25, 26, 29, October 6 (one individual on each of these last dates, with
two exceptions) ; then, in 1905, May 12 (5), 16 (many), 19 (many),
20 (8), 23 (1), 26 (1), June 2 (1), and no more up to September 1,
when the daily observations were discontinued.

Heads collected September 7 gave a few adults in September and
October, but very many more in the following April and May.

Heads collected September 16, October 3, 17, and 27, gave no
adults until the following April, May, and June, when large numbers
issued.

In the last three instances most or all of the adults did not issue
until the next year. Thus the time of emergence is delayed in propor-
tion to the lateness of oviposition.

These records are by no means exceptional ; they are typical ; those
given here were selected from some twenty as being the most complete
and most significant for present purposes.

To summarize: The May and June adults lay their eggs in the
first growth of second-year red clover, and most of the adults derived
from these eggs appear in July and August, but some of them do not
issue until the following May or June. The July and August adults
lay their eggs in the second growth, and some of the adults from these
appear during the same season; the rest not until the following year.
The later the eggs are laid the larger the proportion of individuals to
lie over until the next year. The adults have two times of greatest
abundance, falling near June 12 and August 12 respectively. This
does not mean only two generations, however, but, instead, two lots of
individuals. The first lot (June 12) is derived from eggs laid thruout
the previous season. The second lot (August 12) has no accessions
from the previous year, but is, nevertheless, composite in its nature,
for it consists of adults of both the second generation and the third.
I have traced as many as three generations per year, and there is
clearly a possibility of four. The fact that some members of each gen-
eration lie over until the next year complicates the study of the life
history.

At first, it seemed to me at least possible that the prolongation of
the period of emergence might really be due to re-oviposition in the old
clover heads, even tho the chalcids had been removed every day as fast
as they came to light and no copulation had been observed. This as-
sumption was dismissed, however, after being tested, for the seeds
were all too dry and hard to be penetrated by the ovipositor or to serve
as larval food. There remained only the possibility that some chal-
cids had emerged soon enough after the clover heads were collected to

58

find seeds soft enough for oviposition, but this possibility was too slight
to account for the immense number of late-emerging chalcids. Fur-
thermore, any larve from eggs laid in the jars of clover heads would
soon be disposed of by the drying and shriveling of the green seeds. I
could not find any evidence of re-oviposition.

There is one source of possible confusion that must be guarded
against in studying the life history of this chalcid. There emerges
from the clover heads, along with B. funebris, another chalcid, Tetras-
tichus bruchophagi Ashm. MS., so named upon the assumption that it
is a parasite of the clover seed-chalcid. This Tetrastichus is so much
like the Bruchophagus in general appearance that it might hastily be
mistaken for the latter, tho many differences between the two appear
under the microscope.

Habits——While the clover heads are green, in spring, few if any
of the seed-chalcids will be found; but when they begin to turn brown,
the chalcids appear on them. The males appear four or five days
earlier than the females, and both sexes frequent the clover heads, but
the males do not rush about and explore the recesses of the clover head
in the way that the females do.

On warm sunny days the chalcids are most active, and then most
of the eggs are laid. On rainy days both sexes remain quietly in the
clover heads. They make their home among the florets, and there, at
length, their dead bodies are to be found.

Brown ripe clover heads give the female much trouble, for she
can not insert her ovipositor into a hard seed; green heads she passes
by; florets in full bloom receive some attention and some eggs; but
most of the eggs are laid in florets with withering corollas.

The males are quick to fly when one brings a hand lens near them,
but the busy females occasion the observer less difficulty. The female
squeezes in and out among the florets, often working her way deep into
the flower head, so that one must cautiously spread the florets apart
in order to follow her movements. Every now and then she stops to
clean her antennz with the front legs, or her wings and abdomen by
passing the hind legs backward. With the tips of her palpitating an-
tenne she keeps touching the florets, especially the calyx, as if testing
it. At length she proceeds to lay an egg, and usually pierces the side
of the calyx tube, tho sometimes she stands on the top of the calyx,
between the calyx lobes and the corolla. Bending the end of the abdo-
men forward under the body, she releases the long needlelike ovipos-
itor and thrusts it into the calyx; then the abdomen recovers its normal
form, but the ovipositor, at right angles to the body, remains inserted
in the wall of the calyx, and is pushed and wriggled until its tip has
entered the young seed. After three to twelve “minutes the organ is
withdrawn and rapidly slipped back into place. Sometimes a tiny col-
orless drop of fluid is seen at the tip of the ovipositor just before it
is thrust into the calyx.

The observer, having identified the floret during the process of
oviposition, can then pry it out with a knife and carry it back to be

a2

dissected under a microscope, if he wishes to find the egg. The egg is
found inside the seed in the semifluid albumen. Being translucent and
almost colorless, the freshly laid egg transmits the pale green color of

the surrounding seed tissue and is inconspicuous; but as one dissects
the albumen carefully, the egg comes out like a lump of jelly, soft and
delicate but sufficiently elastic to keep its form. The egg varies con-
siderably in shape and must assume its definite form after leaving the
ovipositor ; for the body of the egg is wider than the channel of the
ovipositor, and no distension of the organ is seen during oviposition.
It is to be inferred that the egg passes thru the ovipositor in the form
of a long thread, the body part of the egg entering the seed first and at
once expanding. The usual position of the egg in the seed, with the
end of the appendage near the seed coats and the body of the egg
farther away, indicates that the body entered first. The appendage
probably serves as a reservoir for some of the egg-contents while the
egg is going thru the ovipositor. This appendage is empty in the
freshly laid egg, and within a day after the latter is laid the former
shrinks and turns brown—then affording a ready means of locating the
egg. Without a careful dissection this delicate appendage will be
missed.

The seeds in which the eggs are laid look sound and healthy and
contain no other insect—so we have always found.

The egg, dissected out of a seed, can be kept for some time in a
glass tube, upon a piece of moist black paper or a fragment of albumen
taken from the seed, and can be examined daily under the microscope
in order to determine the egg period. We kept eggs in this way for
thirteen days, after which they appeared to be dead. Another way is
to take a large number of seeds from florets in which the females were
seen to oviposit, and to dissect these at successively longer intervals
from the time of oviposition, making sure that there is not more than
one egg in each seed. By this method I found that eggs laid July 22
were unhatched and apparently sound thirteen days afterward, but then
the material gave out, and I do not yet know precisely the duration of
the egg stage.

The larva when full grown fills the seed, leaving only the shell
intact.

The adult emerges thru an irregular hole, generally at the top of

the seed (as the seed stands in the calyx). In one instance I saw such
~a hole in the seed when the seed contained not an adult, but a pupa.
The opening was no doubt made by the larva but was probably acci-
dental—for among phytophagous chalcids in general the exit opening
is bitten out by the adult, not by the larva.

Natural Enemies—In company with the seed-chalcid, there
emerged frequently, in our jars of clover heads, a second black chalcid
which might casually be mistaken for the first species, tho belonging to
another genus—Tetrastichus. The species is T. bruchophagi Ashm.
MS., as determined from specimens named by Ashmead himself, and
obtained by Mr. R. L. Webster from Prof. Lawrence Bruner. The

60

specific name may or may not prove to be appropriate in its meaning.
‘At present I know of no direct evidence that the Tetrastichus feeds on
the seed-chalcid, but the parasitic habit of other members of the
genus, and the association of this species with the seed-chalcid, in the
apparent absence of other possible hosts, leads one tentatively to regard
the Tetrastichus as an enemy of the destructive clover seed-chalcid.

Control.—All things considered, the shortage of the seed crop, as
a constant occurrence, is due chiefly to the seed-midge and the seed-
chalcid, in this state. Probably the midge is a little more injurious
than the chalcid; at least, the larve of the former are a little more
abundant than those of the latter.

The chalcid has not attracted the attention that it will from eco-
nomic entamologists, and nothing in the way of preventive measures has
been proposed except the cautious statement by Webster that the same
means recommended for the midge might apply to the chalcid, and that
the destruction of outstanding clover heads and the burning of chaff
and stems after hulling would in all probability greatly reduce the
numbers of the insect.

It is safe to say that early cutting in June would undoubtedly pre-
vent a great amount of oviposition, and if done as soon as the field
came into bloom, would not only forestall most of the oviposition, but
would also dispose of any eggs or young larve that might already be
present in the tender green seeds; for the green unhardened seeds dry
out and shrivel up soon after the leaves and stems dry. Moreover,
early cutting of the hay crop would hasten the maturity of the seed
crop in a way to prevent most of the midsummer oviposition ; not all of
it, of course, for some chalcids would be on the wing whenever the
clover heads ripened. It is true, however, that the life history of the
chalcid has become adapted to that of red clover as it is usually cul-
tivated, and that the two periods of maximum abundance of the chal-
cid coincide with those of the greatest abundance of ripening clover
heads; and it follows that the methods given would largely derange
this adjustment.

The fact that the insect passes the winter inside the seeds on the
ground indicates plowing under as a preventive. This is ordinarily
done anyway after the second year of the clover, and when done at the
usual time—as early as practicable in spring—the plowing doubtless
buries most of the insects beyond the possibility of emergence.

In first-year clover the chalcid lays eggs in such heads as may be
present in the latter part of the season, and these heads are often
numerous. Their seeds, falling to the ground, furnish no small pro-
portion of the chalcids that appear in the same field the following May
and June. It would seem wise, therefore, to clip off or pasture off the
heads of first-year red clover. In fact, something of a fodder crop
can be obtained in the latter part of the first season without injury to
the plant, if the cutting is not done too late in the season.

Volunteer clover is always infested by the chalcid, as well as by
other pests, and ought to be destroyed.

"

61

I have several times examined commercial clover seed and found
some of it injured by this insect, but the inmates of the seeds always
happened to be dead. There is a strong possibility, however, that new
clover seed takes the living insect to the field. Such seed, if sown
broadcast, would permit the adults to emerge; but if drilled in, would
dispose of the chalcids, as they could scarcely make their way to the
surface.

Bruchophagus funebris How.

1880. Howard, L. O.—Rep. [U. S.] Comm. Agr., 1879, p. 196.

1896. Hopkins, A. D—Bull. No. 6, U. S. Dept. Agr., Div. Ent.,
pews:

1898. Hopkins, A. D—Bull. No. 17, U. S. Dept. Agr., Div. Ent.,

ie p. 45;

1899. Pettit, R. H.—Bull! No. 175, Mich. Agr. Exper. Sta., pp.
366, 367.

1904. Titus, E. S. G—Bull. No. 44, U. S. Dept. Agr., Div. Ent.,
pp. 77-80.

1906. Webster, F. M.—Circ. No. 69, U. S. Dept. Agr., Bur. Ent.,
pp. 7-9.

CLOVER SEED-CATERPILLAR

-Enarmonia interstinctana Clem.
(Grapholitha interstinctana)

In its ability to diminish the seed crop, this pest ranks with the
seed-midge and the seed-chalcid. Attacking a clover head that is
green or partly in bloom, the little caterpillar eats out a cavity in the
head, destroying many of the unopened buds and some of the tender
green seeds, and spoiling the head as a whole. When no young clover
heads are at hand, the caterpillar feeds on tender green leaves at the
crown of the plant.

The adult is an inconspicuous little brown moth of the family
Tortricide, and may be recognized by means of its peculiar silvery
markings.

Distribution—The published records show that this insect is pres-
ent in Maine, Massachusetts, New York, Pennsylvania, Washington
(D. C.), Ohio, Indiana, Illinois, Iowa, Missouri, and Michigan. It
probably occurs in other states. In Illinois it 1s well established thru-
out the state, holding its own every year, and becoming locally abun-
dant now and then.

Food Plants and Injuries ——The chief food plant is red clover, but
white clover is also affected, and we have reared the species from
alsike. Lintner quoted a correspondent to the effect that mammoth
clover was not touched by a certain insect which Lintner (Eleventh
Report, p. 153) took to be the seed-caterpillar. The correspondent’s let-
ter evidently refers, however, not to this insect at all, but to the seed-
chalcid. There appears to be no reason why mammoth clover should

62

be exempt from the seed-caterpillar, and we have actually found it on
so-called mammoth, which appeared to be a cross between mammoth
and the common red clover.

Hatcliing usually near the base of a green clover-head, the larva
eats into the head, destroying the green florets as it goes. A small
green head is often destroyed entirely, before it is many days old; a
larger head is injured only locally at first, remaining green on one
side, while the other and unaffected side may come into full bloom
(Pl. IL, Fig. 9). To judge from the external appearance of the head,
either the seed-caterpillar or the seed-midge larva might be the author
of the mischief, and both are often present at the same time. A midge
larva, however, is hidden away in the ovary of a single floret, while the
seed-caterpillar makes a large dirty excavation involving many florets,
and is readily brought to light by tearing open the clover head. The
caterpillar attacks particularly the bases of the florets, and eats every-
thing, including the semifluid ovules; occasionally it eats a soft green
seed but it does not eat into seeds that have hardened. Not infre-
quently two larvz are found in the same head. Even when the direct
injury is confined to a portion of a clover head, the entire head is
ruined, for it at length dries up and loses the rest of its florets, leaving
only the dead brown receptacle.

Less conspicuous, tho not inconsiderable, is the injury at the
crown of the plant, done chiefly in September and October, by cater-
pillars of the same species feeding on the young leaves.

The total amount of injury by this insect is, of course, variable.
In New York, Comstock once found 15 to 20 percent of the heads of
red clover infested. In Michigan, Webster saw clover injured to the
extent of 95 percent. In Iowa, Gillette, Osborn, and Gossard have
found the severest kind of infestation. While not sufficiently abun-
dant to attract attention, the insect is, nevertheless, the unsuspected
cause of a considerable reduction in the seed crop; for the destruction
of one head by a caterpillar means a loss of more than one hundred
seeds.

Stages.—The egg, hitherto undescribed, is at first green, then yel-
lowish white, and is almost orbicular as seen from above, tho it is
flattened ventrally ; the surface is finely granulate and iridescent. The
dimensions are as follows: length, 0.275 mm.; width, 0.26 mm.; and
height, 0.21 mm.

The full-grown caterpillar, 7 or 8 mm. long, has the usual five
pairs of prolegs. The color varies in accordance with the nature of
the food (green tissue, or red floral tissue) from dirty white, tinged
with green, to orange, as in Figure 10 of Plate I]. The alimentary canal
with its greenish or purplish contents shows thru the translucent skin
and shifts in position as the caterpillar moves. The head is dark
brown and polished, caudate occipitally, and deeply immersed in the
prothorax. Prothoracic shield yellowish with a brown posterior bor-
der interrupted by a median line of white; or else dark brown with a
clear median line. The body bears not a few pale stiff hairs, and the

ane

— rE ——

63

dorsal piliferous tubercles are arranged, as Comstock noted, in two
pairs, those of the anterior pair being closer together than those of the
posterior pair.

Comstock has already described the pupa in detail. Essentially,
it is 5 mm. long, brown, with the wing-cases and the dorsum of the
thorax darker than the rest. There are two transverse rows of teeth
on the dorsum of all the evident abdominal segments except the last,
and the blunt anal segment bears posteriorly six stout blackish ex-
curved hooks, and several delicate hooked filaments.

The oval white silken cocoon, 10 mm. long, is usually inconspicu-
ous on account of the particles of excrement or bits of floral tissue
attached to it. .

The adult (Plate II., Fig. 11), expanding only 8 to 10 mm., is a silky
dark brown moth, with brilliant silvery markings that are quite char-
acteristic. The most conspicuous marks are those that make the two
parallel crescents when the wings are closed. Along the anterior bor-
der of the front wing are eight silvery marks (sometimes nine) in
form and position as shown in the figure. In fresh specimens the
front wings show a few patches of iridescent scales. The hind wings
are dark brown, with pale fringes.

Life History—Our field and insectary observations show that
there are three generations of this species every year, without much
overlapping of the broods. Here, the moths of the first generation be-
gin to emerge from the pupe May 15, attain their maximum numbers
May 24 (along with the clover seed-midge), and disappear during the
last of June. In 1907—a late season—we saw no moths until May 21,
and they were most numerous May 30. The moths of the second gen-
eration appear in the form of a few scattering individuals as early as
June 25, but most of them are on the wing during the third week of
July, and a few battered specimens linger over into the first week of
August. The moths of the third generation appear as early as Au-
gust 19, become abundant by August 30, continue to emerge as late as
September 12, and die off by the last of September. Some margin—
a few days—should, of course, be allowed for these dates, Hees are
here given as they appear on our note-slips.

Eggs laid September 2 hatched September 7. The anv period
is from one month to five weeks. The pupal period in July is between
two and three weeks. It is possible to find larve of various sizes at
any time from the last week of May until winter sets in, tho larve are
few and far between when the moths are most numerous.

The moths of the third brood lay their eggs at once, and these
hatch in five or six days; but the further life history becomes twofold,
depending on where the eggs are laid. In the insectary the moths lay
their eggs preferably on young clover heads, but if not supplied with
these they oviposit erratically on fresh or dead leaves or stems. Out-
of-doors in September and October the larvz occur in two situations ;
either in immature clover heads, or at the crown of the plant. In the
clover heads active larvee can be found thruout October, in spite of the

64

frost, and a large proportion of these doubtless succeed in pupating
before winter overtakes them. In the insectary, pupation in October
is the rule. Larva which hatched September 7 spun cocoons October
14, and pupated October 16. One larva pupated September 2, and the
moth emerged June 27.

The fate of the larve that feed at the crown of the plant in au-
tumn is rather uncertain. The earliest ones probably pupate, and some
of the remainder very likely survive the winter as larve. We have not
been able as yet to find any of the larve in early spring, but in Iowa,
following a year of heavy infestation, Gossard found full grown larve
under rubbish and manure, and partly grown larve still in the crowns
of the plants, April 22, tho the number found was only 25 percent of
that found the preceding autumn.

Habits —The moths appear in spring along with the first green
heads of the red clover. When disturbed they take short rapid zigzag
flights and come to rest on a clover plant. In the hot sunlight they
seek the shaded side of a stem or the under side of a leaf, but in the
cooler and darker parts of the day and in cloudy weather they often
alight in full view, and close the wings, forming a little brown triangle
marked with a silvery double crescent as in Figure 11, Plate IT.

The moth, upon alighting, has the peculiar habit, already remarked
by others, of whirling about in a circle several times, with the head as
a pivot, and then reversing the movement before settling to rest. No
explanation for this performance is evident.

Osborn and Gossard have reported the moths as being especially
active in early evening, when they hovered over the clover blossoms
in such numbers as to form a perfect cloud between the observer and
the sun.

In clover that is forming heads, nearly all the larve are at work
in the heads, but a few are present in unexpanded leaf-buds, eating out
the interior tissue.

In first-year clover that has not headed, and in second-year clover
that has been recently cut, the eggs are laid, singly as usual, on young
stems and leaflets at or near the base of the plant, where the larve
hatch and remain.

In first-year clover with oats, the moths are abundant in the new
growth after harvest. Such was the case in a field in Urbana August
30, 1907, at which time none of the new growth had headed. In an
adjoining field of second-year clover, the heads of which were nearly
all brown, the moths had disappeared, leaving the seed-chalcid in

charge of the crop. In September, a good many green heads occur on °

first-year clover, and in these the moths lay eggs rather abundantly.
Volunteer clover is always infested by the seed-caterpillar.

The cocoon is spun in a clover head or at the surface of the
ground, according to the situation of the larva. Comstock gives twenty
to thirty days as the pupal period, and mentions that the pupa works its
way out of the cocoon before giving forth the moth. Osborn and Gos-
sard have found the pupa-cases in abundance on the ground, from
which a brood had just issued.

=

65

Natural Enemies——We have reared several braconid and ichneu-
monid parasites of the seed-caterpillar which await authentic determin-
ation. The following species have been published as parasites of this
host: the ichneumonid Glypta leucozonata Ashm. (Proc. U. S. Nat.
Mus., Vol. XII., 1889 [1890], p. 449), reared in Missouri by Miss M.
E. Murtfeldt; the braconid Phanerotoma (Sigalphus) tibialis Hald.
(Proc. Acad. Nat. Sci., Phila., Vol. [V., 1849 [1850], p. 203), raised in
Washington, D. C., by Comstock; and a second braconid, Microdus
latvemmetus ‘Cress: (Can. Ent., Vol. V:, 1873, p. 53), recorded, from
Missouri, Iowa, Canada, and elsewhere. In Iowa, Osborn and Gos-
sard have reared the last in abundance from cocoons of the clover
seed-caterpillar, and have found that it corresponds exactly with its
host as regards the number and the duration of the broods.

Gossard expresses the presumption that the braconid Bracon ver-
noni@ Ashm. (Proc. U. S. Nat. Mus., Vol. XI., 1888 [1889], p. 619)
is a parasite of E. interstinctana in Iowa, since it is associated with the
latter species in marked numbers and corresponds closely with it in
time of appearance.

Control.—The best remedy for the attack of the seed-caterpillar is
that proposed by Comstock, namely, to cut and store the hay crop
early in June (New York, Illinois, lowa), just as advised for the seed-
midge, in order to kill the larve while still in the heads. The hay
should be handled lightly and stacked or stored as soon as possible.
Osborn and Gossard have attested the value of this method, and have
given these further recommendations: (1) cut volunteer clover in early
June and dispose of the heads speedily ; (2) do not allow clover to run
for more than two years; (3) sow seed on land remote from old fields ;
(4) pasture clover in the fall of the first year; (5) plow an old clover
field under in October or November or in early spring, then harrow and
roll. These practices operate at the same time against several other
clover pests.

Enarmonia (Grapholitha) interstinctana Clem.
1860. Clemens, B.—Proc. Acad. Nat. Sci., Phila., p. 351.
1881. Comstock, J. H—Rep. U. S. Comm. Agr., 1880, pp. 254,

205:
1891. Osborn, H., and Gossard, H. A.—Insect Life, Vol. IV.,
pp. 56-58.

Osborn, H., and Gossard, H. A——Bull. No. 14, Iowa Agr.
Exper. Sta., pp. 166-169.
Osborn, H., and Gossard, H. A.—Bull. No. 15, Iowa Agr.
Exper. Sta., pp. 260-262.
Osborn, H., and Gossard, H. A.—Twenty-second Ann.
Rep. Ent. Soc. Ontario, pp. 74, 75.
1892. Gossard, H. A.—Bull. No. 19, Iowa Agr. Exper. Sta., pp.
571-589.
1896. Lintner, J. A—Eleventh Rep. State Ent. N. Y., pp. 152--
156.

66

PEA-LOUSE, OR CLOVER-LOUSE

Macrosiphum pisi Kalt.
(Nectarophora destructor )

This is a big, green, long-legged plant-louse that has ruined mil-
lions of dollars’ worth of field peas and a great deal of red clover: It
is the dominant species of its
kind on these plants (Fig. 5)
and can scarcely be confused
with any other aphid.

Distribution. — This pest
was, in all probability, intro-
duced with clover and peas
from Europe, where it is
widely distributed and com-
mon, tho it is reported mostly
from England, Germany,
France, and’. Italy. «Jn. -the
United States it has been in-
jurious in Maine, New Hamp-
shire, Vermont, Massachu-
setts, Connecticut, New York,
New Jersey, Pennsylvania,
Delaware, Maryland, the Dis-
trict of Columbia, Virginia,
North Carolina, Ohio, Illinois,
Michigan, Wisconsin, Minne-
sota, Nebraska, Iowa, Ken-
tucky, and Texas. It is wide-
spread in Canada also, OCEuT- Fic. 5.—Clover-louse, Macrosiphum pisi, on stems
ring in Nova Scotia and New of red clover. Natural size.

Brunswick and westward thru Ontario.

Not until 1899 did the louse attract the attention of ees
entomologists; in that year an outbreak in Maryland was reported
upon by W. G. Johnson. He and E. D. Sanderson have written most
of the literature on the species.

Our personal observations of several years, made as independ-
ently as possible, have yielded many facts that were already known
and many that are new. The present account refers especially to the
insect as it occurs in Illinois. In the eastern states the insect is chiefly
a pest on peas. Here, where peas are not grown extensively, it is
a pest on red clover.

Food Plants and Injury——Under the name of “green dolphin”
this aphid has long been known in Europe for its injuries to peas and
vetches, and in minor measure to clovers and various weeds—some
forty plants in all.

In America the aphid has done immense damage to peas and
clovers. It affects especially leguminous plants, but numbers also

67

among its food plants many weeds of diverse families. The more
important of its food plants are red clover, crimson clover, field
pea, sweet pea, vetches (known also as “tares”), beet, lettuce, shep-
herd’s purse, and nettle, not to mention the rest of the weeds. Alfalfa
seems to be immune from attack. Thirty sweeps of the net in red
clover yielded 3000 of the aphids, while the same number of similar
sweeps in an adjoining field of alfalfa gave only 30. This alfalfa
was mixed with some clover, however, and observations on the few
lice that could be found on the alfalfa failed to find them in the act
of feeding. On soy-beans growing next to heavily infested clover,
not a single louse was found. Where crimson clover is grown, the
aphid prefers it to red clover, it is said.

Where peas are grown, the aphid winters in a field of clover or
on weeds (as a wingless female or as an egg), and in spring is con-
fined to these until the peas start to grow, and then it does not get
to the early varieties, tho it devastates the late-sown peas. In early
spring most of the aphids are wingless and remain where they happen
to be, but in late spring (May 1, Delaware) and early summer there
are many winged females that can go from clover to peas and start an
infestation. The first aphids select the youngest leaves and shoots, but
eventually the lice cover the entire plant and sap out its life, rendering
it unfit even for fodder.

In Wisconsin the louse was noticed in a five-hundred acre field of
peas about July 20; in less than a week all the plants were dead and
brown. In Maryland in 1899, the louse destroyed peas valued at
$3,000,000, conservatively estimated, and in 1900, $4,000,000 worth
were destroyed.

On red clover, the youngest leaves and stems are the first to be
attacked, and these wither and die if many aphids are present. Wilted
leaves mark the spread of the pest over the plant. Red clover, how-
ever, can stand a good deal of this injury, and if a heavy rain happens
to occur when the plant is covered with the lice, they are washed off,
and the field is safe for the rest of the season. There are also numer-
ous insect enemies and a fungous disease, which kill off immense num-
bers of the lice. At times a combination of circumstances occurs, how-
ever, under which the plant is killed, root and all. The natural checks
upon the increase of the aphid may be insufficient; but dry weather
seems to be the most important factor. Without rain the plant can
not replace the sap taken by the aphids, let alone make any growth; in
dry weather the fungus can not develop; and in the absence of heavy
rains to wash them off the plants, the aphids thrive. In dry weather,
when the plants are loaded with lice, the cutting of the clover is the
last straw.

In 1903 the louse killed an immense amount of red clover, and
weakened much more, in De Kalb county. Being sent there by the
State Entomologist, I found on the farm of Mr. A. E. Myers, at Mill-
brook, August 19, eighty acres of dead clover roots in one field. Not
one root in a thousand showed any signs of life, and on the ground
were thousands of the cast skins of the aphid. At cutting, the lice had

68

been such a nuisance that the men objected to handling the crop. After
cutting, the clover never revived. In neighboring fields there were
many bare spots where the aphid had killed the clover locally, and in
the growing clover were many centers of new infestation, due doubt-
less to migrant winged females. All the clover in that part of the
county was more or less injured; not only old clover, but also the first-
year growth. Returning to the same region the following summer, to
see the consequences of the injury, I did not stay long, for it was hard
to find a field of clover anywhere. The farmers reported that the
clover had been “winter-killed,’ to their surprise, since the winter had
not been a severe one and the clover had often survived worse winters.
The failure of the clover had discouraged almost all of them from
sowing a new crop. My personal opinion was that the “winter-killing”
would not have occurred had not the plants been weakened previously
by the aphid. Clover is undoubtedly injured by certain winter influ-
ences, especially by being “heaved” out of the ground by frost, but
there must be taken into consideration also the inability of the plant to
face the winter when it has been ravaged by such insects as the aphid
or the root-borer.

Only at rare intervals has there been a bad outbreak of this spe-
cies. In England, according to Kirby and Spence, the havoc wrought
by this aphid in 1810 was remarkable for its suddenness. Equally un-
anticipated was the outbreak of 1899 in some of the Atlantic states
and in Canada. In 1900 the devastation continued in places where the
previous injury had been worst, and a new outbreak occurred in Wis-
consin. Since then no reports of serious damage have been published,
but in Illinois this aphid was locally injurious in 1903, as just de-
scribed, and has menaced the red clover every year from 1903 up to
the present. Heavy rains subdue the louse almost every year.

Description—tThe clover-louse is noticeably larger than any of
the other aphids that frequent the field, the largest females being 6 mm.
from tip to tip. The green color of the louse matches that of its food
plant. The legs are conspicuously long, and the tarsi, distal ends of
the tibiz and femora, as well as the tips of the-cornicles, are fuscous.
The antenne are darker at the joints, with the terminal filament fus-
cous. The eyes are red and prominent. With this general statement
we may pass to a more detailed description of the species.

The generic term Nectarophora is antedated by Macrosiphum
(Pergande, Bull. 44, Div. Ent., U. S. Dept. Agr., pp. 13, 14).

With the other species of its genus, M. pisi has the front of the
head concave, with a large pair of tubercles supporting the antennz.
The antenne, legs, cornicles, and abdominal stylus are exceptionally
long in this genus as compared with other genera of aphids. The wings
are large, the third discoidal vein has two forks, and the stigma is
elongate-lanceolate. The terminal portion of the sixth antennal seg-
ment is very long and bristlelike. Most of the species of Macrosiphum
are large and frequent herbage.

On the basis of Sanderson’s studies we are obliged to regard this
aphid (the N. destructor of Johnson) as the common M. fist, of Eu-
rope, described long ago by Kaltenbach.

69

The alate viviparous female (PI. III., Fig. 1) is 4 to 5 mm. long,
with an occasional maximum of 6 mm., and 1 to 1.5 mm. broad. An-
tenne long, reaching to the tip of the stylus or a little beyond; first

and second segments short and close to the tubercle; third to sixth

segments related in length respectively as 3:2: 1.5: 4, the terminal fila-
ment of the sixth segment being three times as long as the base. Wing
expanse about 11 mm. Fore wing 5 mm. by 2 mm. Cornicles slender,
cylindrical, and long,—1 to 1.5 mm. Abdominal stylus half as long as
the cornicles.

Sanderson gives smaller measurements thruout for the autumn
winged viviparous female, it being only 3.15 mm. in length, with pro-
portions varying a little from those just given.

The apterous viviparous female (Pl. I11., Fig 2) is a little larger
than the winged female, ranging in length from 4 to 6 mm., and the
body is more elongate and fusiform, with longer cornicles (1.25 to 2
mm.) and a longer stylus. This form also is smaller in autumn, as
Sanderson has noted, with much more extensive dark brown or black-
ish markings on the appendages.

The oviparous female is apterous.

The egg has not been described before. It is elliptical, twice as
long as broad (0.5 mm. by 0.25 mm.), and changes from saffron-yellow
to shiny black one or two days after being laid.

The winged male is 2.5 mm. in length, with a wing expanse of 9
mm. It may be recognized by its smaller size, among other things. The
color tends toward pale green or yellow. The dorsal sclerites are dark,
as is also the mesosternum, and there are lateral blackish spots in front
of the cornicles. Sanderson has described this form.

Our insectary notes on one pair of M. pisi taken in coitu refer to
the male as being apterous.

In autumn many of the aphids normally turn yellow; in fact,
some yellow individuals can be found at any time, and aphids that are
diseased usually do become yellow.

Life History.—The clover-louse winters both as a large wingless
viviparous female and as an egg, but the eggs are not numerous.
Many of the females are killed off during the winter. The survivors
are easily found under rubbish in the clover field in the first week
of April and even as early as March 25, tho they are a little slow to
revive. They crawl to the clover plants and proceed to suck the sap
and to bring forth living young, all of which are also females; indeed,
no males appear until the last of the season and no eggs are laid until
then. During most of the season there is nothing but a constant suc-
cession of females, all of them born alive. Most of them are wingless,
tho in any of the generations there may be some females that have ~
wings; these also bear their young alive.

The eggs that were laid on green leaves or stems the preceding au-
tumn hatch a few days after the red clover starts on its new growth.
March 23 Mr. E. O. G. Kelly found newly hatched young on a clover
plant, and egg-shells close by on old dead clover leaves. One of these
aphids, kept on potted clover, produced her first young April 5, and
died May 12, after having brought forth ninety young.

70

Mr. R. L. Webster carried thru the season successive generations
derived from a single female that came from the egg March 23, and
obtained (by breeding always from the first-born) as many as seven-
teen generations, the young of the seventeenth brood issuing Septem-
ber 21 to October 3. In the field, newly born young can be found as
late as November 4, tho we can not name the generation to which they
belong. His more important data may best be given in the form of a
table.

M. pisi
Genera- : 2 | Days to | Days of | Number

tion ous Miepaeaty a aanite life of young

i Mar. 23 Apr. 5 May 12 13 50 90

2 Apr. 5 Apr. 25 May 12 20 37 87

3 Apr. 26 May 8 May 13.24. 4h) 2 17 25

4 May 8 May 20 June 16 | 12 39 89

5 May 20 May 31 June 9 | ral 20 49

6 June 1 June 10 June 20 9 19 41

7 June 10 June 19 July 17 9 Si. aii

8 June 19 July 1 July 17 i) 28 60

9 July 1 July 10 Aug. 2 9 32 63
10 July 12 July 22 Aug. 3 10 22 30
11 July 22 Aug. 3 Aug. 15 12 24 44
12 Aug. 3 Aug. 11 Aug, 16:5 ~) 8 13 34
13 Aug. 11 Aug. 21 Aug. 30 10 19 16
14 Aug. 21 Sept. 1 Sept. 5 11 15 8
15 Sept. 2 Sept. 12 Sept. 15 10 13 10
16 Sept. 12 Sept. 21 Oct. 4 9 22 53

ANEKARES: < cte tre Scat suis ate aorta ey Reve 11 25.4 46

The averages are worth notice. A female begins to reproduce
eleven days after birth, as a rule; this accounts for the large number
of generations. The average number of young is not large for an in-
sect, for insects as a whole average at least two or three hundred eggs
per female. The average given in the table is confirmed by one based
upon a large number of additional observations taken thruout the
season. A female is, however, capable of producing as many as 147
young, and many of the females at death have embryos of various
stages in their bodies.

The largest number of young produced in one day by one female
is 13, and the average number 6, in our experience; while the bearing-
period of the female averages 12.1 days. In October and November the
females bear but few young, but some of these females hibernate and
produce more young the following year.

Our breeding experiments, it should be said, were eaaeenes in-
doors, where the aphids were protected from every source of danger.
Out-of-doors the mortality would probably not be so small.

R. L. Webster’s continuous.sobservations on the life history are a
useful addition to our knowledge of the species. His results are cor-
roborated by those of Mr. E. Q. Snider, who, while a student at the

=

71

University of Illinois, made a similar series of studies. He began with
the first hibernating females that he could find, and traced their
progeny. One of the females found April 8 brought forth the first
young aphid April 17, and this acquired wings April 29. In the field I
have seen winged individuals at all times up to November 10.

Five apterous viviparous females studied by Snider bore, respect-
ively, before the end of June, 104, 108, 110, 124, and 147 young. The
last number is unusually large even for an aphid.

Males and oviparous females were not found until October (with
one exception—a female born September 22) ; and males were taken in
the field October 10, 17, 20, and November 3. Copulation was observed
in the field October 20 and November 3; in the last instance oviposi-
tion began twenty-five minutes after copulation ceased. Six females
began to oviposit, respectively, October 18, 20, 21, 31, and November
3 and 4. One female im coitu October 20 laid eggs October 26 (2
excel) oli(2), Wovember3:(4.),,.45C1); 5. (l);6.(2)5-18 (2);
and no more up to December 2, when the observations ended. A fe-
male born September 22 laid an unfertilized egg October 18. A female
taken in the field October 11, 1904, laid eggs October 21, which hatched
March 23, 1905. The eggs have escaped the notice of previous ob-
servers. Here, the eggs are common.

Habits—When these aphids are as yet few, they select the young-
est leaves and stems of the plant, especially the under sides of the
leaves; but as they increase, they spread over the plant, and may
crowd together so closely that large numbers fall to the ground for
want of standing room.

The rapid increase in the number of individuals is not due to any
extraordinary prolificacy, but results from the rapid growth and conse-
quent early maturity of each aphid and from the fact that almost every
individual is a female.

While the aphid is growing, the moults occur at short but variable
intervals, as appears in the following table made from R. L. Webster’s
notes. :

M. pisi
Bere First Second Third Fourth First
por er Born moult moult moult moult young
tions
1 March 23 | March 28 | March 31 | April 2 April 4 April 5
1 March 23 | March 25 | March 31 | April 4 April 9
2 | April 5 April9 | April 12 April 15 April 21 April 25
2 April 5 April10 | April 13 April 18 April 21 April 26
3 | April 26 | April29 | May 1 May 3 May 5 May 8
4 May 8 May 12 May 15 May 20
S May 20 May 22 May 23 May 25 May 28 May 31
6 June 1 June 3 June 5 June 7 June 9 June 10
| June 10 June 12 June 13 June 15 June 17 June 19
9 July 1 July 3 July 4 July 6 July 7 July 10
g) July 1 July 3 July 5 July 6 July 10 July 11

72

Thus there are four moults, or five instars, and the mother does
not reproduce until after the last moult.

Another student (J. P. Gilbert) found five moults in one instance:
an isolated female, born June 20, moulted June 23, 26, 27, 29, and 30.
Each cast skin was removed as soon as found, and five of them were
found.

More interesting than the number of moults is the fact that the
females reproduce for many successive generations without the aid of
the male—-a normal phenomenon among aphids, and many other in-
sects as well—and also the fact that the young are born alive. This
can easily be witnessed, as aphids are so numerous. In this species
the young aphid emerges hind end first and back upward, and envel-
oped in a delicate membrane, which it gets rid of by means of vigorous
kicking. The entire process, requiring ten or fifteen minutes, 1s essen-
tially as described elsewhere and in more detail for other species.

The mother does not wander much after beginning to reproduce,
but stays in one spot, with the younger of her progeny clustered
around her. ,

The winged females, which may occur in any of the seventeen or
more generations, are the chief means of spreading the species. They
are feeble of flight, but are often assisted by the wind to reach distant
places.

Fertilization is evidently essential to the production of an egg
that will hatch, tho eggs are laid whether fertilization has occurred or
not. The deposition of an egg requires about seven minutes, as noted
by E. ©. G. Kelly, who observed also that the female used her hind
legs to assist the egg out. A fluid that accompanies the egg serves to
glue it to a green leaflet, on either side of which the egg may be laid.
The eggs remain over winter on the dead leaves or stems on the
ground.

In November there are still many mature females in the field, and
they feed on mild days, crawling under shelter when the weather turns
cold. If clover sod is brought indoors during the winter, the females
appear with the new growth and the plants soon become overrun with
aphids. Out-of-doors, most of the hibernating females meet their
death sooner or later during the winter, in this region, notwithstanding
the fact, reported by W. G. Johnson, that the species can survive
severe freezing.

Natural Enemies—The most important enemy of this louse is a
common fungus, Empusa aphidis. It is wide-spread in the United States
and Canada, and affects a great variety of aphids, its abundance, when
it occurs, being proportional to that of its host. It does not appear in
dry weather but is common after a rain or two at any time during the
growing season, and is most abundant under the combined influences
of moisture and warmth. Then it sweeps off myriads of aphids.
Those killed by the epidemic remain clinging to the plant in a more or
less lifelike attitude, but turn yellow and then light brown, become
swollen, and eventually coated with the fungus (PI. III., Fig. 3). The

#3

appearance of the insect is at first similar to that caused by the pres-
ence of a larval Aphidius in the body of the aphid. The parasite,
however, at length spins a silken cocoon under the aphid, and when-
ever present can easily be found by dissection.

The life history of this fungus is like that of E. spherosperma, as
given in some detail in the account of the clover leaf-weevil, and is
discussed at length by Thaxter in the Memoirs of the Boston Society

of Natural History, Vol. IV., 1888, pp. 175-177.

Macrosiphum pisi is affected, directly or indirectly, by a large
number of other insects, of which other writers have recorded twenty.
These and thirteen additional species are listed below.

: Gryllide
Q(écanthus confluens H. & H.
MS.
Pentatomide
Podisus maculiventris Say
(= spinosus Dall.)
Euschistus variolarius P. B.
Acanthude@
Triphleps insidiosus Say
Chryso pide
Chrysopa oculata Say
Chrysopa rufilabris Burm.
Chrysopa plorabunda Fitch
Syrphide
Ocyptamus (Baccha) fusci-
pennis Say
Platychirus quadratus Say
Syrphus americanus Wied.
Syrphus ribesii L.
Allograpta obliqua Say
Mesogramma marginatum
Say
Mesogramma politum Say
Spheerophoria cylindrica Say
Ichneumonde
Bassus leetotorius Fab.

Coccinellide
Megilla maculata DeG.
Hippodamia glacialis Fab.
Hippodamia convergens Guer.
Hippodamia_ tredecimpuncta-
tao.
Hippodamia parenthesis Say
Coccinella novemnotata Hbst.
Coccinella sanguinea L.
Adalia bipunctata L.
Chilocorus bivulnerus Muls.
Lampyride
Podabrus rugulosus Lec.
Cecidomyude
Diplosis sp.
Bracomde
Perilitus americanus Riley
Trioxys (Praon) cerasaphis
Fitch
Aphidius fletcher1 Ashm. MS
Aphidius washingtonensis
pee estind. IVES:
Chalcidide
Isocratus vulgaris Walk.
Pachyneuron syrphi Ashm.
Acarina, Rhyncholophide
Rhyncholophus parvus Banks

Most of these species I have studied in Illinois in their relation

to M. pisi.
up to the present date.

Below is a summary of all that we know on the subject
All these insects, concerned in one way or

another with the clover-louse, are either predaceous or parasitic.
Coccinellide—The omnipresent ladybird beetles and their larve

are in this region the most efficient of the insect enemies of the clover-
louse. The larvee in particular destroy the louse in immense numbers.
_ They are by no means limited to this aphid, but when it predoininates,
the number of Coccinellide present is a good measure of the abun-
dance of the louse.

74

The hemispherical, brightly colored ladybird beetles (Fig. 6) are
familiar, tho their larve are not so generally recognized. The ento-
mologist knows them as
active little alligator-like
creatures, with a_ long
warty or spiny abdomen.
Some of them are black-
ish, but most of the com-
mon kinds are spotted
with conspicuous colors.
The pupa is attached by
the tail to a silken support
spun by the larva on a
green leaf or other object.
Its period is four to eight Fic. 6.—Ladybird, Megilla maculata: a, larva; b, empty
days, usually five or six in pupal skin; c, beetle. (Chittenden, Cire. 43, Bur. Ent.,
July, in the case of several U.S. Dept. of Agriculture.)
of our common species. The yellow elliptical eggs, laid in small clus-
ters, are conspicuous on green leaves and elsewhere.

Coccinellide in general hibernate as beetles, and all the species
mentioned here do so. They are among the first insects to appear in
the warm days of late March and early April. Comparatively few at
the opening of the season, they multiply rapidly, tho in this respect
they lag somewhat behind the plant-lice on which they feed, if the
latter are at all numerous. Coccinellide feed also on scale insects,
pollen grains, spores, etc., as Forbes found (Bull. No. 6, Ill. State Lab.
Nat. Hist., 1883, pp. 33-64), but feed chiefly on plant-lice, and thus
are beneficial.

Adalia bipunctata and Hippodamuia glacialis were not often met
with in the clover field, and Coccinella sanguinea was not numerous.
Chilocorus bivulnerus, well known as a destroyer of scale insects, was
rather common at times as an enemy of the clover-louse. The other
species listed above were always common. C. 9-notata we noted as
emerging as a beetle June 29, July 16 and 18; C. sanguinea, June 23;
H. 13-punctata, July 15, 16, and 18; M. maculata, June 20, 21, 22,
and 24; H. parenthesis issued July 1, 2, and 5, from pupe found June
27; and eggs of this species, found June 14, hatched June 20, one of
the larve pupating July 11 and giving the beetle July 15.

All the species listed were actually seen feeding upon M. pisi,
either in the field or in the insectary. In the latter place, the diet of
three Megilla maculata beetles included also (to their discredit) one
coccinellid pupa, one adult C. sanguinea and two beetles of their own
kind, besides some of their own eggs and (to their credit) eggs of the
Colorado potato-beetle that were offered to them.

Perilitus americanus, a braconid parasite of the beetle of Megilla
maculata and now and then of C. 9-notata, we reared several times
from the former host. Parasitized beetles taken on clover leaves June
17, gave the winged braconid June 21 and 22; others, of June 23, gave

75

the adults June 30. My own experience with the parasite leads me to
take no exception to the accounts already published by Riley (Insect
Life, Vol. 1., pp. 101-104, 338, 339) and by Weed and Hart (Psyche,
Vol. V., pp. 188-190). Briefly, it may be said the beetle is found
standing on a leaf and looking quite natural; indeed, it can still move
some part of itself in most instances, tho it can not move away from
the spot, for it is held by its feet to a brown mass of silk—a cocoon,
from which the parasite will emerge in its winged form. The beetle
may remain alive in this condition for two weeks and doubtless a
little longer, but when disentangled from its foothold it is unable to
move its legs in coordination—is unable to walk.

The larva that made the cocoon has issued from the beetle and
could previously have been found inside the host, but some mystery
exists as to where the larva makes its exit, for the shell of the beetle
appears to be unbroken.

This Perilitus, then, is a check upon the beneficial ladybird beetle,
but is of no practical importance on account of its infrequency.

On many occasions I have seen adults of Podisus maculiventris
(spinosus) and Euschistus variolarius sucking the pupze of various of
the coccinellids that prey upon the clover-louse. The eggs of both
these pentatomids are heavily parasitized by a proctotrypid.

Syrphide.—Among the commonest insects of the clover field are
several species of Syrphide, or flower-flies (Fig. 7, 8), some of which
are known also as “sweat bees.” Many of these flies are banded with
black and yellow, and have the habit of poising over this or that spot
for a few moments and making short dashes from one place to another.
The flies lay their eggs in or near colonies of plant-lice, upon which
the larvee are to feed. The larve are leechlike in form, and generally
green, yellow, or mottled brownish in color. They are often seen
among the aphids, which they destroy at a rapid rate. The syrphid
larva seizes an aphid between its hooklike jaws, holds it aloft and
sucks the blood from the body, meanwhile waving itself to and fro.
When full grown, the larva shortens and its skin hardens into a brown
pear-shaped or elongate puparium, from which the fly will issue.

In this region the flies are seldom noticed in the clover field be-
fore the latter part of April, but are abundant by the last of May.
The larve grow rapidly, and there are several generations of the com-
mon species each year.

In Maryland, Johnson found the syrphid larve to be the most im-
portant of the insect enemies of M. pisi, which they nearly extermi-
nated in some localities. One pea grower sieved out twenty-five bush-
els of syrphid larve in a few days.

Allograpta obliqua Say, he found to be by far the most common
and most important species, forming the greater bulk of the twenty-
five bushels mentioned. He refers to the larve as being pea-green,
slightly streaked with white, and one quarter to one third of an inch
in length when full grown. The puparium is usually found on a leaf
or stem, rarely on the ground.

76

Sanderson, in Delaware, found almost all the puparia of Allo-
grapta obliqua to be parasitized by Bassus letotorius Fab., and from
several puparia which seemed to have been parasitized by the Bassus
were bred the chalcid Pachyneuron syrphi Ashm. B. letotorits is also
parasitized by /socratus vulgaris Walk., according to Fletcher.

A. obliqua is a common species in Illinois, where the larva feeds
on M. pisi as well as on other aphids.

Syrphus americanus Wied., one of the largest species of the
family, has conspicuous bands of black or yellow, and buzzes like a bee
when on the wing. The larva is greenish or mottled brownish, at-
tains a length of half an inch or more, and pupates on the plant or
a little below the surface of the ground, as Johnson noted. The
species deposits a single small oval white egg in a colony of plant-lice,
and one of the larve has been observed to eat twenty-five plant-lice in
as many minutes, according to Sanderson. In Delaware, he found it
to be extremely abundant as an enemy of M. pisi; in Illinois, it feeds
on the same species and is frequent but not conspicuously numerous.

Syrphus ribesu L. is reported from Canada, by Fletcher, as an
abundant foe of the aphid, and as being attacked by Bassus letotorius,
which, in turn, falls prey to the chalcid /socratus vulgaris. S. ribesu
occurs with us, but I have never happened to take it in the clover field.

Spherophoria cylindrica, a small syrphid named by others as
affecting M. pisi, is rather common here in aphid-infested clover fields.

Mesogramma politum (Fig. 7, 8) is frequent in our clover fields,
the green larva feeding on the clover-louse. A full-grown larva found
on the ground March 27, made its puparium the same day, and the fly
issued indoors April 8.

Syrphus-fly, Mesogramma politum: Fig. 7, adult; Fig. 8 (a), larva,
(b) puparium. (Riley and Howard, U. S. Dept. of Agriculture.)

Mesogramma marginatum has similar habits and is common. A
puparium found on a clover leaf June 21 yielded the adult June 22.

Platychirus quadratus, a small and frequent species, and the less
common Ocyptamus fuscipennis, I have taken in sweepings, along with
the abundant M. pisi. It is probable that their larve feed on the
clover-louse.

‘we!

77

Various syrphid larve that destroy M. pisi are themselves attacked
by Podisus maculiventris (spinosus) and Euschistus variolarius; and
the eggs of these pentatomids are parasitized by a proctotrypid, Teleno-
mus podisi Ashm. (determined by A. A. Girault).

Chrysopide.—A few species of Chrysopa (Fig. 9) are common in
the clover field. The adults, known as lace-wing flies, are green or
less often yellow, with golden eyes and four similar gauzy wings, finely
netted with veins. A few species have a characteristic odor—C. ocu-
lata, for example. By day the flight is rather sluggish, but toward
evening the lacewings become more alert; they often fly to a light at
night. Most of the species hibernate as pupz, so far as is known, but
plorabunda winters as an adult. We have often found it hibernating
under dead leaves; then the insect is brown in color. Our spccies lay

Hi Wheertscwnrenecns soe

Ny ee ale

Fic. 9.—Lace-wing Fly, Chrysopa oculata: a, eggs; b, larva; c, foot of same; d, larva
devouring pear-tree Psylla; e, cocoon; f. adult; g, head of same; fh, adult, natural size.
(Chittenden, Cire. 43, Bur. Ent., U. S. Dept. of Agriculture.)

their eggs each at the tip of a long stiff thread and always in the vicin-
ity of plant-lice, which are the chief food of the larve. In clover
fields the eggs are common on leaves or stems, and the larve eat raven-
ously M. fisi and other aphids, and eat one another now and then,— _
particularly when a lot of them issue at the same time from one cluster
of eggs. The prey is seized between the points of the long, tapering
mandibles of the aphis-lion and the blood is sucked back thru a chan-
nel made by a groove along the inner face of the mandible, against
which the maxilla fits, to form a closed channel. A newly born larva,

78

unless cannibalistic, selects for its first meal a small tender aphid;
under the microscope, one can see the watery juices of the victim bub-
bling along the transparent jaws of the captor. These larve are active
creatures, gray, yellowish, or brownish in color, tho colorless at birth.
They grow rapidly, and in one to three weeks spin a silken cocoon by
means of glands opening into the rectum. The cocoon, spherical or
oval, shows, after the emergence of the adult, a circular lid.

The Chrysopa lJarve are undoubtedly important checks on the
clover-louse. In red clover I have found three species, namely, ocu-
lata, plorabunda, and rufilabris. The last was not common; but the first
two were numerous, and their larve were frequently seen feeding on
M. pisi, wpon which we reared them in the insectary.

A larva of oculata, taken July 7, spun July 10 or 11 and gave the
adult July 27.

A larva of plorabunda gave precisely the same record. A second
larva of this species, taken in a colony of M. pisi, spun July 10, ina
bent leaflet, the adult issuing July 20.

C. rufilabris emerged July 24 from a cocoon found on a clover
leaf July 20.

We have reared no parasites of Chrysopa, but others have ob-
tained from cocoons of this genus many species of chalcids and a few
ichneumonids, and from the eggs one proctotrypid.

The most important of the predaceous foes of the clover-louse be-
long to the three families just discussed. There remain to be treated,
several predaceous species of more or less importance.

While the seed-midge works havoc in the clover heads, another
member of the same family is busily engaged in reducing the numbers
of the clover-louse, at least in Canada, for all that we know about this
helpful but undetermined species of Diplosis is what Dr. Fletcher
learned at Ottawa, where in 1900 it was by far the most inveterate
enemy of M. pisi on pea-vines. These minute orange maggots would
transfix an aphid, hold it up, and suck out the blood, in much the same
way as the syrphid larve. Their growth was so rapid as to result in
several generations during the season. Winter was passed in a minute
cocoon, spun on the stem of the plant or on the ground among grains
of sand.

At Highland, Ill., August 11, I found on the red clover large num-
bers of both sexes of a tree-cricket (CG2canthus), and watched them
devour the clover-aphid at a great rate. Afterward we kept these
tree-crickets alive in the insectary for a long time and found it no
small trouble to keep them supplied with enough plant-lice. Big, as
compared with their victims, they soon cleaned a plant of aphids. One
male ate nineteen full-sized aphids at one meal, lasting fifty-five min-
utes, an aphid being finished in ten to ninety-five seconds,—about one
louse per minute on an average. In this instance, it should be said,
Mr. Kelly facilitated matters by handing the cricket a new aphid as
soon as the old one was finished. The same cricket, on the following
day, being induced to repeat his performance, beat his previous record

te

Dom

79

by devouring eleven aphids in eighteen minutes, but fell short of his
record for fifty-five minutes.

As an inveterate enemy of M. pisi, this Gcanthus is undoubtedly
far ahead of Dr. Fletcher’s Diplosis in capacity, but unfortunately does
not appear to be wide-spread, tho it is probably
common in southern Illinois.

This species of Gicanthus agreed with none
of the published descriptions, but I found that
Mr. C. A. Hart and Mr. J. D. Hood had seen the
same species and given it the manuscript name of
confuens.

Triphleps insidiosus, an active little flower-
bug (Fig. 10) frequently impales M. pisi and
sucks its blood. In our breeding experiments
with the clover-louse this little intruder had to be |. 10.—Triphleps insid-
excluded, as it played mischief with the birth- iosus. Enlarged. (Af.-
records. ter Riley.)

Podisus (Fig. 11) and Euschistus (Fig. 12) as nymphs or adults
destroy a clover-louse once in a while, as I noticed.

Iie. 11. — Podisus maculiventris, nymph, Fic. 12.—Euschistus variolarius. Four times
sucking the blood from a caterpillar. natural size.
Natural size.

The soldier-beetle (Podabrus rugulosus) was found feeding on M.
pisi in Maryland, by Johnson.

A small red mite (Rhyncholophus parvus) was noted by Sander-
son as feeding on M. pisi in Delaware.

Let us now turn to the parasites of Macrosiphum pisi.

A phidius—Often there is found on a clover leaf a dead aphid,
light brown in color, with the body distended, attached to the leaf in a
somewhat lifelike position by means of a little silken mat, which

80

spreads out under the aphid and raises it above the surface of the leaf.
‘Pl. IIL., Fig. 4.) This cocoon was made by a maggotlike larva that

had been feeding inside the body of the aphid. The winged braconid ~

emerges by cutting nearly a circle thru the skin of the host, usually
thru the abdomen, and leaves a circular opening with usually a cor-
responding lid. The mother Aphidius inserts a single egg into the
body of an aphid.

Two species of Aphidius are named in the literature as destroying
M. pisi: A. fletcheri Ashm. MS., reported by Fletcher as having done
good service in Ottawa, Can., and bred from M. pisi in Delaware by
Sanderson; and A. washingtonensis Ashm., also bred by Sanderson

under the same circumstances. In Delaware, at least 5 percent of the

lice were killed by these parasites.

In Urbana, Aphidius is abundant every season on the clover-louse.
We have had the adults emerge June 21, 26; July 1, 3, 4, 6, 8, 12, 17;
August 18, 24; and October 18, 19, —mostly early in July, however.

An Aphidius larva that I found July 11 spun its oval silken carpet
under the aphid on the same day; July 12 the aphid had been raised
above the leaf and the cocoon was complete; July 18 the adult was
found, it having issued during the preceding twenty-four hours. An-

other black larva spun June 18 and the imago emerged June 26. From _

a cocoon made October 12 the adult issued October 19.

October 10 a female Aphidius was put into a cage containing M.
pisi, the individuals of which had been reared under glass in a way to
insure their freedom from parasites. No oviposition was witnessed
(the mother dying October 21), but November 16 three of the aphids
showed the cocoons of Aphidius, the aphids having turned brown on
the day before. These aphids were kept over winter in glass vials,
and June 10 a winged Aphidius was found to have emerged. It was
dead then, but certainly did not issue before March 17, when the vials
were thoroly examined.

Another braconid, Triorys (Praon) cerasaphis, was bred in large
numbers by [letcher from material collected at Ottawa, Canada, the
material referred to being by implication M. pist.

From what has been given it can be seen that a good many differ-
ent insects have to do with Macrosiphum pisi in one way or another,
and that the interrelations of some of them are involved. Thus,
Megilla maculata, which eats M. pisi, is parasitized by Perilitus ameri-
canus, and preyed upon by Euschistus variolarius—the eggs of which
are food for one of the proctotrypids. Syrphide destroy M. pisi and are
themselves food for the same Euschistus; furthermore, they are para-
sitized by Bassus letotorius, which, in turn, is parasitized by Pachyneu-
ron syrphi and Jsocratus vulgaris.

Among the natural enemies of this aphid is to be counted the
English sparrow, according to a correspondent of Dr. J. B. Smith, who
wrote, “It was wonderful to watch them, how soon they cleared up a
pea-vine. After the sparrows commenced to work, they soon cleared
up every louse.”

-

ee
<r

81

Control—The treatment of the pest is different according to
whether the insect feeds on peas or on clover.

Growers in the eastern United States and in Canada have found
that early peas are practically exempt from injury, and therefore plant
the early-maturing varieties when injury is probable.

On peas grown for commercial purposes, spraying is too expen-
sive, besides being in other respects impracticable, according to John-
son’s elaborate experiments in Maryland. Sanderson found, in Dela-
ware, some little advantage in spraying while the lice are still confined
to the terminals and the vines are as yet upright.

A crop can be saved by the timely and thoro use of the “brush and

cultivator” method devised by Johnson. This method requires that the

peas be planted in rows 24 or 30 inches apart, instead of being sown
broadcast. The lice are brushed off the vines with switches of pine
branches or something similar, and are then buried under ground by
means of a cultivator drawn by a single horse. Cultivation should not
be repeated for three days, in order to insure the death of the buried
lice. Ona hot day, Johnson found that lice left on the surface of the
ground died in a few minutes when the temperature of the air was
94°-96° F., and that of the ground 115°-119° F. In one instance, 600
acres of peas were saved in this way; and tho forty men were neces-
sary for two weeks to brush and cultivate the peas, the crop netted the
owner 25,000 to 30,000 cases of peas of two dozen cans each.

Instead of a cultivator a large shallow pan can be used, and the
lice brushed into this as it is dragged between the rows by hand. In
such a contrivance, containing a little water and kerosene, Johnson
collected a bushel of lice to each row of 125 rods. The pan, made of
galvanized iron, may be five or six inches deep, and as wide as the
distance between the rows. Sanderson recommends this method as
being perhaps the best one. It can be used when the soil is too damp
for the cultivator.

Sanderson states that high fertilization (as with crimson clover

‘and lime), with frequent cultivation for several years, often enables a

crop of peas to mature in spite of the louse.

As the louse winters in the clover field and spreads from clover
to peas, these should be planted as far from clover as possible. If the
lice are abundant on clover in spring it may be advisable to plow the
clover under, and roll the ground, in order to save the peas (Sander-
son).

In gardens the louse can be controlled on green peas and flow-
ering sweet peas by spraying, as with whale-oil soap (1 pound to 5
gallons of water) or kerosene-soap emulsion, diluted with 12 parts of
water. I*letcher reports success with a spray of whale-oil soap and
tobacco decoction. He put 10 pounds of tobacco leaves into half a
barrel of water, strained off the liquid after a few hours, added 2
pounds of whale-oil soap, and, when this was dissolved, added enough
water to make 40 gallons. Two days after the application of this
spray to both surfaces of the leaves most of the lice were dead, and

82

such parts of the rows as had received two applications were cleared
of the insects.

On red clover I have seen this aphid multiply in spring until its
numbers threatened the life of the plant, and then disappear, practi-
cally, thru natural agencies; this for five successive seasons. A heavy
rain did the work assisted by the fungus Empusa aphidis and, second-
arily, by the numerous and important—tho somewhat lagging—pre-
daceous and parasitic insect foes of the aphid. Were it not for these
influences the louse would become a pest of the first magnitude in
spite of the vigor of the clover plant. Occasionally and locally it does
become such a pest, as already related.

Unfortunately, it can not be predicted whether the clover will be
killed or not, and if one is unwilling to take the chances, the safest
thing to do is to cut the clover just as soon as possible. Cutting and
drying the clover will kill most of the lice at any time during the sea-
son.

The hordes of lice are for the most part the progeny of the fewer
lice of May, in the same field. So it follows that spring pasturing or
clipping back the clover would check the multiplication of the louse.

The lice of April and May are the progeny of a comparatively
few wintered females that entered the field the preceding year, and
also of a few eggs laid the previous autumn in the first-year clover.
Therefore it is advisable to cut or pasture the clover in the latter part
of its first season—and this will not hurt the plant if done intelligently.

Macrosiphum pist Kalt.
1899. Johnson, W. G.—Bull. No. 20, N. S., U. S. Dept. Agr.,
Div. Ent., pp. 94-99.
1900. Johnson, W. G.—Can. Ent., Vol. XXXII., pp. 56-60.
Chittenden, F. H.—Bull. No. 23, N. S., U. S: Dept. Agr.,
Div. Ent., pp. 33-37.
Johnson, W. G.—Bull. No. 26, N. S., U. S. Dept. Agr.,
Div. Ent., pp. 55-59.
Sanderson, E. D.—Bull. No. 26, N. S., U. S. Dept. Agr.,
Div. Ent., pp. 69-72.
Sanderson, E. D.—Bull. No. 49, Del. Agr. Exper. Sta., pp.
14-24.
Fletcher, James.—Rep. Exper. Farms Canada, 1899, pp.
170-174.
1901. Sanderson, E. D—Can. Ent., Vol. XXXIII., pp. 31-39.
Sanderson, E. D.—Twelfth Rep. Del. Agr. Exper. Sta.,
1900, pp. 169-186.
Fletcher, James.—Rep. Exper. Farms Canada, 1900, pp.

211-213.
Chittenden, F. H.—Circ. No. 43, U. S. Dept. Agr., Div.
Ent., pp. 1-8.

1902. Sanderson, E. D.—Thirteenth Rep. Del. Agr. Exper. Sta.,
1901, pp. 168-172.

Wy

83

CrLover LEAF-WEEVIL
Phytonomus punctatus Fab.

Tho this insect must be counted among the most important clover
pests, it has not as yet established itself as an annual menace to the
hay crop. Indeed, it is ordinarily held in check by a great variety of
adverse influences, and seldom gets control of the plant—reminding
one, in this respect, of the army-worm.

In early spring the larvae make small round holes in the leaves of
second-year clover, as soon as the leaves have begun to grow; later,
they eat inward from the margin, the injury increasing in April and
May. Thruout the summer the beetles gnaw the clover leaves in a
ragged fashion and may even eat the plant down to the roots.

The Jarve and beetles are not seen in the daytime, unless one
hunts for them; they are nocturnal in their activity. The larva, curled
up under rubbish on the ground, are green with a white stripe along
the middle of the back; they have no legs and are sluglike when in-
active. The adults—tough, oval, brown beetles—are also found on
the ground during the day, motionless, with the legs and antenne
drawn up against the body, or else moving away sluggishly when ex-
posed to the light.

Distribution—tTho this species has been familiar to European en-
tomologists for more than a century, occurring as it does thruout
Europe and in western Siberia, it was not recognized in this country®
until 1881, when its ruinous work was reported from Yates county,
New York. At present the species is known to occur in Vermont,
Rhode Island, Connecticut, New York, New Jersey, Pennsylvania,
Delaware, Maryland, District of Columbia, West Virginia, North Car-
olina, Ohio, Indiana, Illinois, Michigan, and Wisconsin, and also in
Ontario, Canada. From the data collected by F. M. Webster, the in-
sect appears to have spread from New York into Chio, then westward ;
also from New York into Canada. At Ridgeway, Ont., Mr. A. H.
Kilman found that the beetles were being brought by the east wind,
August 10, 1884. On the same day, at Buffalo, N. Y., ten miles due
east of Ridgeway and across the lake, the beetles swarmed on the
pavements and could be collected by the quart along the lake shore.
Reinecke noted their abundance in Buffalo following a heavy east
wind.

Food Plants and Injuries —The food plants in Europe are given as
Trifolium (clover) and Medicago sativa (lucerne, alfalfa). In the
United States the insect eats all kinds of clovers, and alfalfa as well.
The other food plants that have been named, are beans and timothy for
the larva, and burdock and the flowers of goldenrod for the beetle.

Webster observed a preference for white clover over red. In
central Illinois red clover is most heavily infested, alfalfa coming sec-
ond, and white clover third. Mammoth clover and alsike are freely
eaten if they happen to be available.

European accounts refer but scantily to this species as a pest,
aside from references to its devastations in Italy in the years 1867-70;

84

and in this country the insect, tho often abundant, seldom accomplishes
the injury anticipated because the larvz are usually killed in spring by
a fungous disease. When this species cooperates with the root-borer,
in a time of drought, injury of the worst kind may ensue.

The larvz eat the leaves, and the beetles eat the leaves and stems
also, as described later.

Description.—The egg is easily visible as a yellow object (chrome-
yellow at first), elongate oval, 1.1 mm. long and 0.6 mm. broad. It
darkens in from two to six days after being laid, and the surface is
then rough, and sculptured with hexagonal depressions.

In the clover field the larve of this species (Fig. 13) can not easily
be mistaken for anything else. They are green usually, and lie on the
ground curled head to tail. Close examination shows that they are
footless and have a brown head, while along
the middle of the back is a white or pale
yellow stripe edged with rose-red or black-

Fic. 14.— Clover leaf-weevil, Phytono-
mus punctatus, cocoon. Greatly en-
larged.

ish red. The youngest larve, to be sure,
Fic. 13.— Clover leaf-weevil, differ from this description, for when only
Eee Pee 1.5 mam. or 2)mm. long, they ate qwitite: or
pale yellow, with a jet-black head and only
a suggestion of the characteristic median dorsal stripe; they are ‘curled
up on the ground and sluggish, however, just like the older larve.
Riley (1882, p. 178) gave a detailed description of the larva in its
four stages. The body tapers gradually toward each end. The color,
white at hatching, becomes green as soon as a meal has been taken.
Some larve, however, are distinctly yellow- instead of green, and a
few are bluish green. The head, black in the first stage, becomes
afterward brown or yellowish brown. The second stage (after the
first moult) is marked by the appearance of the broad white dorsal
line, bordered on each side by a blackish streak, and the length of the
larva is 4mm. After the second moult this line is more conspicuous
and the length of the larva is 5 to 7 mm. With the third and final
moult, the larve become decidedly green, tho the posterior part of the

we bow

85

body remains yellowish; the dorsal line becomes tinged with rose
color and edged with blackish rose; length 8 to 14 mm. The cocoon
is oval (Fig. 14), 9-10 mm. long and 6.5—-7 mm. broad, and is com-
posed of a coarse network of brownish threads. .

The newly formed pupa (Fig. 15) has a yellowish green head,
small black eyes, and yellow antennz, legs, and wing-pads. The abdo-
men is dark green with a pale dorsal line, and bears numerous hairs at
its extremity and a transverse series of dorsal sete on each of its seg-
ments.

The beetle (Fig. 16) is a stout, oval, brown, finely punctured cur-
culio. The female is about 8 mm. in length and 4.5 mm. in greatest
width, some specimens being as long as 8.5 mm. The prevailing color

Fic. 15. Fic. 16. -

Clover Leaf-weevil, Phytonomus punctatus: Fig. 15, pupa; Fig. 16, beetle.
Greatly enlarged.

above is brown, but the sides of the prothorax and elytra are washed
with pale yellowish brown, which on the elytra covers the outer five
interspaces. Occasionally there is a pale sutural line. The elytra are
marked above with small black spots, due to scales which occur at regu-
lar intervals on the interspaces. The prothorax is much narrower than
the abdomen, subquadrate, and one fifth broader than long, with the
sides rounding anteriorly and converging slightly posteriorly. The
pronotum has three pale longitudinal lines, one in the middle and one
on each side. The eyes are transverse. The beak is half as long
again as the head, stout and curved, with deep antennal grooves. The
scales and the short sparse sete of the body are either brown or yel-
iow.

The male, 7 mm. in maximum length, differs from the female in
being smaller and narrower, with the sides of the elytra less rounded;

86

it is also darker in color than the female, with a narrower pale area on
each elytron, the two outermost interspaces being dark instead of pale.
The pygidium (which is not exposed) is, as usual in the family Cur-
culionide, divided by a transverse suture so as to form an additional,
or anal, segment; thus the male has eight “dorsal segments” and the
female seven.

P. punctatus is distinguishable at once from our other species of
Phytonomus by its coloration, large size, and stout beak. As to smaller
differences, punctatus is characterized by having mandibles that are not
emarginate at the tip, while the first and second segments of the funicle
are equal; in the other species of the genus the first segment is stouter
and often longer than the second, and the beak is longer and more
slender than in punctatus. In the clover field, this beetle will be recog-
nized without difficulty.

Life History.—In central Illinois we have only one annual gener-
ation of this insect, as seems to be the rule elsewhere. All thru the
winter small larva can be found in the clover field under rubbish on
the ground or between the bases of the clover stems. In early spring
the few warm days that start the clover on its new growth revive the
larve also, and they begin to mar the fresh clover leaves with little
round holes eaten out of the blades of the leaflets. In the early season
of 1907 the first new leaves of red clover began to show March 19, and
were already riddled by these larvee March 23, at which date the larve
were common on the ground near the affected plants. In early spring
the larvzee are of many sizes, with an-average of 5 mm. in length, tho
many are only 2 or 2.5 mm. long, and a few are as long as 7 mm. I
have rarely found the beetles in early spring, and such as were found
were either dead or in the last stages of decrepitude, and evidently in-
capable of doing anything toward the propagation of their kind.

I have not found more than four larval stages—the number given
by Riley. The first stage lasts about nine days, in the insectary; thus
larve born November 16 moulted for the first time November 25.
Some of the larve, born in late autumn, do not moult until the following
March or April. For example, one larva was in its first stage April
1; it moulted April 8, April 17, and May 4, and spun May 20. The in-
tervals between moults are, however, very variable, especially when the
weather is unsettled, and the growth of the larve is consequently in-
termittent.

The pupal period indoors we have found to be 10 to 20 days, as
in four instances following:

(1) Spinning occurred April 22; pupation, April 24 ; emergence, May 11.
(2) Spinning occurred April 22; pupation, April 24 ; emergence, May 14.
(3) Spinning occurred April 24; pupation, April 30; emergence, May 20.
(4) Spinning occurred May 20; pupation, May 27; emergence, June 6.

Larve of various sizes are common in April and May, but nearly

all attain their growth before June 20. Rarely, beetles of the new gen-
eration appear as early as May 9; on that date we once found two

87

freshly emerged beetles in the field. The latest date for their emer-
gence may be given as July 15. Many beetles issue daily from June
5 to June 30, and most of the beetles issue during the last week of
June.

Early as the beetles appear, they do not begin to mate until the last
week of August, and nearly all the eggs are laid in September and

October.

We have insectary records of oviposition for almost every day be-
tween September 17 and October 26, and almost daily records of
hatching from October 9 to November 27. The egg period in autumn
is from 23 to 45 days, averaging 29 days; the length of the period de-
pends upon temperature chiefly; some of the latest eggs, indeed,
do not hatch until the following spring. Out-of-doors we have found
eggs as late as November 14, and young larve as early as October 10.
After that date they soon become common, and can be found at any
time during the winter between the bases of the clover stems, as deep
as possible, or else on the ground under more or less protection. Many
of them succumb to the cold, however. These winter larvee also are
of various sizes. Sixty-five larvae measured November 26 ranged in
length from 2.5 mm. to 7.5 mm., with an average of 3.17 mm.

Late in October a few living beetles—more than three months old
—occur in the clover field and go into hibernation. [Early in the fol-
lowing spring their dead bodies may be found. Farther south, it is
possible that enough beetles survive the winter to influence the course
of the life history.

The preceding general account of the life history is based upon
such a large body of observations that it represents the actual condi-
tions with considerable accuracy, for central Illinois. A few precise
notes are added on account of their significance.

Many eggs laid between October 16 and 25, 1905, were apparently
sound January 21, 1906, and had not hatched February 23; but
March 21, young larvae from them were found, still alive, and 2 mm. in
length. Again, eggs laid October 26, 1904, did not hatch until April
13; 1905.

I have several times followed the consecutive life history for a
year or more. The longest account, covering a period of eighteen
months, begins with a female beetle taken September 23,1904. She
laid eggs as follows:

Sept. 26, one mass of eggs.

Oct. 1, three egg-masses; hatched Nov. 3 and 4; larve alive Nov.
21, but died during winter.

Oct. 9, several eggs laid; they hatched November 19; the larve
died in winter.

Oct. 26, several eggs laid; unhatched April 12, 1905; hatched
April 13.

Nov. 1, three eggs; hatched Nov. 27, in warm room. The mother
was alive Nov. 21, but died during the winter.

The larve that were born April 13, 1905, were reared ; they buried

88

themselves in the ground May 23 and 24 and gave beetles June 13.
Four of these beetles were kept alive until August 28, and August 29
one male and one female remained. The female laid eggs Oct. 16, 17,
21, 24, and 25. These eggs had not hatched February 23, 1906, but
had just hatched March 21; by March 29 the larve had died, however,
from a scarcely excusable neglect to supply them with food. The
parent beetles had died the year before, about November 11.

This account of the life history is in some respects at variance
with that of Riley (1882, pp. 175, 176). In central Illinois the egg
period in autumn is. from 23 to 45 days in the breeding-cage. Fur-
thermore, none of the larve born in autumn give beetles in that season ;
the beetles do not emerge until the following June or thereabouts, and
some of these are the beetles that will enter upon hibernation. In my
experience, no eggs are laid in spring. In a warmer latitude than this
there might very well be a second generation of beetles, to hibernate
and to lay eggs the following spring. Indeed, in this latitude, the little
autumn larvze, if taken indoors and fed, will produce beetles in mid-
winter.

Here, then, the clover leaf-weevil winters chiefly as a small larva;
occasionally in the egg; never as a pupa, in my experience; and rarely
as a beetle. No eggs are laid in spring, however, and there is clearly
but one generation a year, tho this generation is straggling instead of
compact.

Habits —The larve that have hibernated are ready to eat the red
clover as soon as it starts on its second year’s growth. At any time
during the winter one can get plenty of these larve by digging up
clover sod and starting the growth of the clover indoors.

In midwinter, on a mild day (Jan. 6, 1903), the larve were feeding
in abundance on red clover plants in Urbana, Ill (R. D. Glasgow)—
and in broad daylight. This is unusual, for at other times of the year
they feed only at night or else at dusk or in daytime when the sky is
sufficiently cloudy. Ordinarily, when the sun is shining they are found
curled up in shaded situations, usually on the ground, but occasionally
among the stems of their food plant. When feeding at night the larger
larve drop to the ground.when approached, but the smaller ones re-
main clinging to the leaflets, just as Riley observed. The larva fre-
quently curls itself around the edge of a leaflet and bites out a small
round piece from the blade; or it may secure a hold by gripping a hair
of the leaf between two of its body segments. Only the youngest larve
make the little round holes in the leaflets; the older larvz eat gaps in
the edges.

The feeding of the larve in spring is more or less intermittent,
being suspended at every cold spell. In 1907, when the entire month
of April was cold in central Illinois and frequent freezes blackened
more than one third of the red clover leaves, the larve of the leaf-
weevil, like their food plant, made no growth during the month of
April, but became dormant again until May, tho they had been active
during the warm weather of late March. Retarded in their develop-

89

ment by one month, they made up in May for what they had lost, and
the majority of the beetles appeared at the usual time in June.

The locomotion of the larva is peculiar. The larva secures a hold
on a hair by means of its mouth; then brings forward the end of the
abdomen to secure a new hold, and stretches forward the rest of the
body. Tho the larva is termed footless, it has, nevertheless, paired
ventral fleshy tubercles which, from their anatomical relations, are evi-
dently equivalent to the legs of other larvz; also a median ventral pro-
thoracic tubercle. These muscular tubercles assist in locomotion,
especially on smooth surfaces. As the larva walks on the under side
of a sheet of glass, slightly moistened, a suckerlike action of these
tubercles is evident.

The color of the larva is white at birth, but a green tinge appears
as soon as the larva has taken its first meal of green plant tissue.
Some larve are yellow instead of green; diseased larve are generally
yellow, tho not all yellow larve are diseased. Now and then a larva is
found having a decided blue tinge.

When full grown the larva buries itself just under the surface of
the soil and makes an oval cell, against the smooth wall of which it
spins the cocoon; once in a while the cocoon is constructed among the
bases of green clover stems. The cocoon, oval in form, consists of a
coarse network of threads with round or oval meshes; it is pale yellow
at first, becoming brownish with age. The actual spinning is done
with the mouth. The first threads are laid in haphazard fashion across
one another; but after a coarse framework has been made, the larva
lays the later threads along beside the earlier ones, forming a stout
network, and gradually reducing the meshes to small rounded holes.
At intervals the supply of silk fluid in the mouth gives out; then the
larva reaches back to the end of the abdomen and by an assiduous
process of nibbling secures a new supply of the silk fluid from the rec-
tum, and resumes its spinning. This performance always occurs, and
can be observed easily with a hand lens in the earlier stages of cocoon-
spinning. Riley and J. A. Osborne were each partly correct in their
accounts of the spinning (Riley, 1882, p. 175).

The beetle eats its way out of the cocoon and enters upon a long
and lazy existence of feeding by night and resting by day. Not until
the last of August do the beetles arouse to reproductive activity. In
summer they are sluggish in the daytime, under debris on the ground,
but at night they are contrastingly alert. They reduce clover leaves to
tags, beginning at the margins and eating inward, usually leaving the
stout bases of the veins, but sometimes devouring the entire plant down
to the ground—stalks, flower heads, and all. Incidentally, they spot
the plants with a brown fluid. Like the larve, they are quick to drop
when approached.

We have many times kept these beetles alive all summer, waiting
for them to lay eggs. When the time comes they lay the conspicuous
yellow eggs in profusion in the breeding-cages, with or without method,
as the case may be. The female may scatter her eggs about promis-

90)

cuously or place them in small bunches on the plant or elsewhere. In
other instances she bites a hole in a clover stem and inserts an egg
lengthwise, pushing it far in or leaving it sticking out of the stem.
Sometimes she makes a cavity without laying an egg in it. Often the
female eats her eggs. In a breeding-cage that is sufficiently shaded,
eggs may be laid during the day; normally they are laid at night. Mr.
R. L. Webster observed oviposition in our insectary October 16, begin-
ning at 6:30 p.m. He found a female clinging to a clover stem, with
her head downward, and piercing the stem with her rostrum, thrusting
it in almost to the antennz. At times she would raise the body on the
front pair of legs as if throwing her entire weight on the beak. Having
made a sufficiently large hole, she reversed her position and inserted a
single egg; the actual oviposition took not more than twenty seconds.
Then she made another hole but did not attempt to lay an egg in it.

Out-of-doors the eggs are found inserted into clover stems, but
occur also, to some extent, on the base of the plant, where the stems
join; rarely they are found on the ground.

The male often accompanies the female on her round of oviposi-
tion and there are repetitions of the process of fertilization, alternating
with the periods of oviposition. September 25, a pair of beetles were
put on potted red clover; Sept. 27, twelve eggs were laid; Sept. 28,
six; Sept. 29, several; Oct. 5, several; Oct. 8, several more ;'Oct. 17,
copulation occurred, probably for the second time; Oct. 23, more eggs
were laid; Oct. 31, the female was missing.

The largest number of eggs that we have obtained from one
female is forty.

Usually the female takes three or four weeks to lay all her eggs,
under insectary conditions. In the field the period of egg-laying ap-
pears to be shortened, in the last of the season, by frost. ;

Our observations on the habits of this species are in accord with
those of Riley, except as regards some minor details of locomotion and
silk-spinning.

Natural Enemies——Riley notes the larva of a small beetle, Col-
lops quadrimaculdatus, as feeding upon the eggs of the clover leaf-
weevil, and Cicindela repanda as probably preying upon the larva of
the weevil. In Europe various ichneumons parasitize Phytonomus
larve, but in this country no such parasites have come to light as yet.

Webster mentions the fact that the larve are destroyed by birds,
and that barnyard fowls, especially turkeys, are very fond of them.

The worst enemy of the leaf-weevil is an epidemic disease, that
under favorable conditions sweeps off the larve by the wholesale.
This disease, due to a fungus, needs damp and not too cold weather
for its development, and affects the larve in April or May and again
in October and November, but not during winter. The contagion is
rapid and thoro; no matter how abundant the larve are, the infection
spreads until, after two to four weeks, it is almost impossible to find a

91

living specimen. “The sick larve of all ages crawl up the herbage
during the night, and instead of again concealing themselves near the
ground on the approach of light, as the healthy ones do, ascend as high
as possible, and if on grass, coil themselves in a horizontal position
about the apex of the blade, or if on other objects, take a position as
nearly similar as the shape of the object permits. If disturbed before
the middle of the forenoon, the majority are still able to crawl, although
sluggishly; by noon most of them are quite dead, but unchanged in
appearance. It will be found that they cling to the leaf with greater
tenacity than during life........ Late in the afternoon, the body has
changed from the normal yellowish or pea-green and smooth appear-
ance to a velvety gray. The next morning there is only a small, black-
ened and shriveled mass remaining, while the surrounding foliage is
powdered with a whitish, clinging dust, composed of the spores of the
fungus. If some of the dead insects had been placed on a pane of
glass, and a tumbler inverted over them during the night, they would
have shrunken less, and been covered with a white fleecy growth, while
on the glass, surrounding each body, would have been a white halo of
spores two-thirds of an inch in diameter, such as everyone has ob-
served about dead flies on the window in autumn. This is the general
course of this rapid and fatal disease.” (J. C. Arthur.)

This fungus, known as Empusa (Entomophthora) spherosperma
Fres., is found in the body of the larva as a network of colorless
branching threads (mycelium) which absorb the fluids of the body;
some of the branches push thru the ventral wall of the body and attach
themselves to the nearest surface as holdfasts (rhizoids); other
branches pierce the skin and form a gray velvety coating on the body
of the larva, and the tips of some of these branches each form a spore
(conidium), which is finally projected forcibly into the air, to infect
any other larva that it may happen to hit. These temporary spores
germinate at once, pushing out one or more threads, which enter the
host and grow, forming a mycelium. There are also resting spores;
these develop within the body of the host and are capable of surviving
for a longer period than the temporary spores.

Other and more technical details in regard to the fungus are given
by J. C. Arthur (Fourth Rep. N. Y. Agr. Exper. Sta., 1885 [1886], pp.
258-262) and by Thaxter (Mem. Boston Soc. Nat. Hist., Vol. IV.,
1888, pp. 172-175).

This fungus is by no means dependent upon the clover leaf-weevil
for its existence, for it has a long list of hosts, representing most of the
larger orders of insects. The list includes the common cabbage-worm,
mosquitoes and some other flies, ichneumons, certain leaf-hoppers, etc.
Fortunately, also, the fungus is widely distributed in America as well
as in Europe. In this country the ravages of the fungus on the leaf-
weevil have been reported from nearly every region in which the
weevil has been injurious.

92

Control.—The reported outbreaks of the larvz in spring have al-
most always been suppressed by the virulent disease just described.
This disease prevents the summer damage by the beetles, often killing
the larve before they have done much injury.

Riley’s recommendation to plow badly infested clover under in
May rather than to allow it to become a source of contagion, has sel-
dom been followed unless the clover root-borer also has been present,
for the leaf-weevil by itself has not often done an immense amount of
damage.

The fact that the young larve hibernate, led Riley to mention the
possibility of crushing them or burning them, but he added his doubt
as to the practicability of killing them by rolling or by burning the
clover stubble in winter.

The necessity for the employment of any remedy does not appear
until the clover is well on in its second year’s growth. If damage is an-
ticipated, however, it would seem advisable to pasture the clover lightly
or to clip it back in spring; this does not hurt the clover, is highly de-
sirable as a means of forestalling the attacks of some other clover
pests, and might check the larve of the leaf-weevil somewhat, tho it
is possible that they would subsist on the cut stems until the new
growth started; and in cold weather they can live a long time without
any food.

After the second season red clover should be plowed under to get
rid of this and other pests, as well as for agricultural reasons.

Phytonomus punctatus Fab.
1882. Riley, C. V—Rep. [U. S.] Comm. Agr., 1881-82, pp. 171-
179.
Lintner, J. A.—First Rep. Ins. N. Y., pp. 247-253.
1884. Kilman, A. H.—Can. Ent., Vol. XVI., pp. 144, 145.
1896. Webster, F. M.—Bull. No. 68, Ohio Agr. Exper. Sta., pp.
27-31.

CLOVER ROOT-BORER

Hylastinus obscurus Marsh.
(Hylastes obscurus, H. trifoli Mull., Hylesinus trifolii Mull.)

This pernicious root-borer is gradually spreading over the United
States and Canada, and has already ruined crops of clover in New
York, Ohio, Indiana, and Michigan. Often the injury done by this
insidious insect has been attributed to drought or disease. The in-
jury appears in the wilting and death of the plant. A badly injured
plant breaks off easily at the crown; the roots are burrowed out length-
wise, and in the burrows can be found white footless grubs, or little,
dark brown, cylindrical beetles, as tough in body as the others of their
family, Scolytide.

v4

93

Distribution——This beetle was introduced from Europe, where it
has been known for more than a century, feeding chiefly on red clover

a a ‘but also on alsike. In this country it first attract-
Toil : : é

yell 5) ed attention as a pest in 1878 in central New

iy: York. Thence it spread westward in the region

A ie

of Lake Erie, doing great damage in Ontario,
Can., in 1888, appearing in Michigan in 1889 at
the west end of Lake Erie, and after that spread-
ing over southern Michigan with disastrous con-
sequences. In Ohio it was injurious by 1890,
and seriously so in the northwestern part of the
state in 1893. It has reached Indiana, Lllinois,
Pennsylvania, West Virginia, and North Caro-
lina, and has even been reported from Oregon.
Food Plants and Injury—In America the
chief food plants are red clover and mammoth
clover; others being alsike, alfalfa, and the pea.
First-year clover, its roots being small in
spring, when the beetle lays its eggs, is not known
to be attacked by this borer; second-year clover
is attacked; and clover that has been allowed to
run for more than two years harbors the pest in
abundance.
An affected plant finally wilts and dies ;
when pulled by hand or by the mower it breaks
_ off at the surface of the ground. The roots of
such a plant are burrowed out longitudinally
(Fig. 17), the burrows, with their walls more or
less decayed, contain the excrementitious parti-
Tha cles of the insect, and usually the insect itself in
Ai, one or more of its stages, tho the beetles, being
4 a. small, sluggish, and inconspicuous in color, are
Tic. 17.—Clover Root-

: easily overlooked. Small cylindrical holes thru
borer, Hylastinus ob- the sides of the roots are characteristic of this
tan Bae species, as indicating the emergence of beetles.
Ent., U.S. Dept. of Ag- The amount and rapidity of injury depend
riculture. ) :

not only upon the number of insects present but
also upon the amount of moisture received by the plant. In dry
weather the plant succumbs quickly to the borer, but in wet weather
the plant, tho weakened, may continue to survive. Injured plants are
liable to die late in June or early in July, after cutting; tho with plenty

of rain many of the crippled plants may live until winter. In 1893

and 1894 the root-borer, in combination with the leaf-weevil and dry

weather, caused a general failure of the clover crop in Michigan.

The borer is said to be responsible for an irregular, imperfect
blooming of the clover or a failure to bloom at all. If the plants sur-
vive, thanks to copious rains, the yield of seed is liable to be almost
nothing. In central Illinois the root-borer is generally distributed, but

94

is not a pest as yet, tho Mr. J. A. West, assistant to the State Ento-
mologist, found alsike injured by it at Monticello in 1907.

Fie. 19.

Clover Root-borer, Hylastinus obscurus: Fig. 18, beetle; Fig. 19, larva; Fig. 20, pupa.
Greatly enlarged. (Webster, Circ. 67, Bur. Ent., U. S. Dept. of Agriculture.)

Stages —The beetle (Fig. 18) is small—at most only 2.5 mm. in
length—dark brown or blackish, cylindrical, hard-bodied and_ hairy.
The elytra, or wing-covers, often have a reddish tinge, and are coarsely
punctate; and the head and pronotum are more finely punctate, the lat-
ter bearing sparse long hairs. The tibiz have large teeth near the outer
end.

The egg is minute, tho visible to the naked eye, white, and elliptical,
with a smooth, shining surface.

The larva (Fig. 19) is stout, white, with yellow head and brown
mouth parts, footless, and 3 mm. long when full grown.

The pupa (Fig. 20) is white, with a pair of spinelike projections
at the extremity of the abdomen, and another pair on the top of the
head. The pronotum shows a feeble median ridge and bears a few
scattering bristles.

Life History and Habits —There is but one generation a year. In
Ohio, where Webster worked out the life history, the insect winters in
clover roots as a beetle and also, tho less commonly, as a larva, the
latter pupating in spring. The beetles leave the roots during May and
fly about. The eggs are laid mostly from May 15 to June 20 in cavi-
ties eaten out by the females in the crown of the plant or down on the
sides of the roots. In each cavity the female lays several eggs. Mr.
G. C. Davis found females laying eggs inside the root, in the burrows,

the eggs being packed into the dead wall of the burrow and covered.

with refuse. The larve, the first of which hatch late in May, feed for
a time where they hatched, then tunnel along the roots, making one or
more longitudinal galleries with occasional side branches, and filling
the burrows with excrement. The pupa is found at the end of a bur-
row. Most of the larve pupate before the first of August and most of
the pupze transform to beetles before the first of October. The beetles

~~

95

remain in the roots, however, until the following spring, feeding mean-
while, when they are not dormant.

In Chio, according to Webster, larve and adults can be found at
almost any time of the year, tho the beetles are rare in July. Pupe
are most common in July, but occur in August and even up to the mid-
dle of November, and a few pupz, newly formed, are met with in early
spring. Eggs have been found as late, or as early, as September 18 in
Michigan.

Most of our articles on this insect have simply been based on the
excellent accounts that Riley, Webster, and G. C. Davis published, and
the species needs more study than it has received.

Here in central Illinois the life history and habits are as Webster
found them to be in Ohio.

September 9 a pair of the beetles were observed im coitwu in one
of our cages. The conditions were not quite natural, however, for I
had taken the beetles from roots and put them on potted clover; out-
of-doors they probably would not have left the roots until spring. As
soon as they were placed on the plant, September 8, they began to
burrow into the crown; they mated the day after; October 3, a long
burrow was found, containing several larve at its lower end, but no
eggs; one of the parent beetles was still alive on November 21.

Only one natural enemy of the clover root-borer has been put on
record—a telephorid larva, probably Telephorus bilineatus Say, men-
tioned by Riley as preying on the larva of the borer.

Control.—A badly infested field should be plowed as soon as pos-
sible after the removal of the hay crop, in order to starve the grubs by
drying out the roots. The plowing must not be delayed, for early in
July (latitude of Ohio, Webster) the larva begin to pass into the qui-
escent, or pupa, stage, in which they take no food; then they would
doubtless transform and emerge as beetles in some numbers in spite
of plowing.

In Ontario, Can., the value of clover as a green fertilizer is so
generally appreciated that the farmers do not hesitate to plow the
clover under at the first signs of the presence of the root-borer.
(Fletcher. )

Another thing: Red clover should not be permitted to straggle
along after the second year to furnish a nursery for this pest and
others.

Fertilizers do not kill the root-borer and will not save the plant—
so Mr. G. C. Davis concluded from his experiments with nitrate of
soda, muriate of potash, and kainit. Generally speaking, fertilizers as
used against a root-feeding insect act more by stimulating the plant
than by affecting the insect directly.

Hylastinus obscurus Marsh.
1879. Riley, C. V.—Rep. [U.S.] Comm. Agr., 1878, pp. 248-250.
1880. Lintner, J. A——Thirty-ninth Rep. N. Y. State Agr. Soc.,
1879, pp. 41, 42.

96

1894. Davis, G. C—Bull. No. 116, Mich. Agr. Exper. Sta., pp.
41-47.

1896. Webster, F. M.—Bull. No. 68, Ohio Agr. Exper. Sta., pp.
31-33.

1899. Webster, F. M.—Bull. No. 112, Ohio Agr. Exper. Sta., pp.
143-149.

1905. Webster, F. M.—Circ. No. 67, U.S. Dept. Agr., Bur. Ent.,
pp. 1-5.

CLover Hay-wormM

Hypsopygia costalis Fab.
(Pyralis costalis, Asopia costalis)

The clover hay-worm works in stacked or stored clover, eating
much of it, and contaminating much more with webs of silk and parti-
cles of excrement, making the hay unfit for fodder.

This species, described as long ago as 1775, has been sufficiently
infrequent in England to be valued by the collector. It inhabits cen-
tral and southern Europe, northern Asia, northern Africa, and a large
part of North America. In this country its destructive work has been
seen in New Hampshire, Massachusetts, Connecticut, New York,
Maryland, West Virginia, North Carolina, Ohio, Indiana, Illinois, Ken-
tucky, Tennessee, Alabama, Kansas, Missouri, lowa, Nebraska, Michi-
gan, and in Ontario, Canada.

In Illinois the species is widely distributed, according to the
records of the State Entomologist, and has done no little damage in
various parts of the state. :

Injury.—The larve attack the bottom of a clover stack to a height
of two feet or more from the ground; similarly, in the barn, they
occur near the floor. They interweave the hay with white silken webs,
intermixed with black pellets of excrement resembling coarse grains of
gunpowder; they reduce much of the hay to chaff, and their webs
give the hay the appearance of being mouldy; in fact, such hay actu-
ally becomes mouldy if it has been lying near the ground. This hay is
refused by horses and cattle and is fit only to be burnt. When the hay
is removed, swarms of wriggling brown caterpillars are left.

The pest evidently prefers dry clover hay. In mixed clover and
timothy, the former is eaten and the latter is left, altho 50 percent of
such hay may be damaged when the hay is three quarters timothy
(Webster). One writer, it should be said, has reported serious dam-
age to pure timothy in Kentucky. Webster reared the larve on grow-
ing clover heads, in the insectary, and, furthermore, obtained the moth
in large numbers (June 3 to July 15) from masses of dead grape
leaves taken May 5 on the ground in a vineyard. In summer the
caterpillars are confined to the old unfed hay, and the infestation is
worst on hay that has lain over, year after year.

97

Osborn mentions Pyralis farinalis, as well as H. costalis, as injur-
ing stored clover hay in Iowa.

Stages——The full-grown caterpillar (Fig. 21) is three quarters of.
an inch long, and dull brown with an olive tinge usually, tho some of
the largest larve re-
tain the pale color of
the young larve. The
head, shield, and cau-
dal plate do not turn
dark until after the
last moult, according
to Riley. The thorac-
ic segments are much
wrinkled, and most
of the EAST See Fic.. 21.—Clover Hay-worm, Hypsopygia costalis, larva.
ments are each di- Greatly enlarged.
vided by a transverse
groove into two subsegments, the anterior of which is the larger. On
each segment are several smooth shining areas, each bearing a fine
white hair.

The cocoon is half an inch in length, oblong-oval, and composed
of white silk, intermingled with excrement and bits of hay.

The chrysalis, as described by Riley, is honey-yellow, with the
segments and members clearly defined by the darker color of the “in-
sections.”

The moth (Fig. 22) is small—the largest specimens spreading 22
mm.—and has silky wings tinged with purplish above, margined with
orange, and fringed with golden yel-
low. On each of the upper wings are
two large golden spots so situated as
to divide the front margin of the wing
into thirds; each of these spots con-
tinues backward to the hind margin
of the wing as a narrow lilac line. On
each hind wing are two wavy trans-
verse straw-colored lines, one across

Et ESO 1 as the middle of the wing, and the other
Twice natural width. half-way between the first line and the

base of the wing. Underneath, the
wings are pale yellowish with the markings indistinct. Head and legs
straw-colored ; antennz and palpi pale orange, tinged with lilaceous.
Life History and Habits—In Missouri and Ohio there are two
generations a year and apparently more or less of a third brood. In
winter, larvze of all sizes are to be found in clover hay. In Ohio, Web-
ster found pupz no earlier than May 25; moths emerged June 12 and
laid eggs June 13 to 17, other moths issuing from June 3 to July 15;
young larve (very small to half grown) occurred July 1; larve and
pupz were seen August 6; and adults of the second generation began

98

to emerge August 8—larve from these being found August 15. In
Connecticut, pupe and many grown larve occurred June 7 (Britton) ;
a pupa formed June 5 gave the moth June 18; most of the moths dis-
appeared by July 15 (in a certain barn); the first larvae of the second
generation were taken in a stack of clover September 1; and larve
were not found in barng until two or three weeks later.

In Illinois the hay-worm is destructive in winter and spring, as
elsewhere. The records of the State Entomologist refer to its occurrence
January 6 at Griggsville; February 4, Midland City; February 18,
Shelbyville; March 25, Deland; April 6, Fillmore; May 21, Ridge-
farm; and May 27, Parkersburg. A correspondent in Shelbyville re-
ported the caterpillar from cheat, mixed with wheat and timothy.

The office notes include a great many records of the capture of
the moths from June 2 onward. June 6, two moths, numerous pupe,
and a great many larve were present in a box of infested clover hay
received from Parkersburg; and other moths issued June 10, 19, and
20. Dr. Forbes recorded moths of this species as being abundant July
10 to 20 and far less abundant July 28. They disappear about the last
of July—those of the first generation—after flying thruout the months
of June and July. The moths of the second brood appear a little be-
fore the middle of August. Moths are constantly seen from that time
until the middle of October, but the last of these perhaps represent a
third generation.

In the breeding-cage, eggs may be laid on growing clover heads,
as appears from Webster’s experiments, hence it is possible that the
same thing occurs in the field.

_ Out-of-doors, the moths are seen flitting about clover stacks at
dusk or in cloudy weather (June 29, Ohio). At night they often get
into houses and fly toward the lights.

The caterpillars, of all sizes, can be found at any time during the
winter, and in a barn they are active when everything outside is frozen.
Warmth and moisture are greatest at the bottom of the clover, and
there these caterpillars flourish. When you pick them up they are
likely to wriggle out of your hand; they can wriggle backward as
well as forward. They spin a lot of silk, and construct little silken
cases for themselves, as do the clothes moths; they are continually
spinning, and are often seen hanging from a thread of silk. These
caterpillars are gregarious, or sociable; they gather together while they
are feeding, tho they separate and wander when full grown and ready
to make their cocoons.

No insect enemies of this pest are as yet known.

Control.—In a barn, old refuse clover-hay should be removed and
burned if this insect is present, before new clover is put in. A stack
of clover hay should be raised above the ground on a foundation of
logs or rails, in order to keep the bottom of the stack as dry and cool
as possible. It has been found that salting the hay at the bottom for
two or three feet will preserve it from injury. Some farmers habitu-
ally salt their clover hay, using about two quarts of salt to the ton.

99

Webster’s experiments indicate that the caterpillars can be killed
at once in a clover stack by the use of pyrethrum. He had five tons
of clover restacked, dusting it with this insect powder, using ten
pounds of pyrethrum to fifty pounds of flour, and found in a sample
of the hay that the majority of the caterpillars were dead the day after.

Britton, in Connecticut, tried bisulfid of carbon in a stack and
hydrocyanic acid gas in a barn, but in both instances the clover had
become packed so solidly that only a few caterpillars—those on the
outer part of the heap—were killed by the treatment.

We need to know more about the life history and habits of this
insect notwithstanding the large number of articles that have been
written on the species, for these, with a few exceptions, add nothing
to Riley’s original account of 1874.

Hypsopygia costalis Fab.

1874. Riley, C. V.—Sixth Rep. Ins. Mo., pp. 102-107.

1891. Webster, F. M.—Insect Life, Vol. bite poral 22

1894. Davis, Ghee BaitiNe. 116, Mich. Agr. Exper. Stat, pp:
56-58.

1896. Lintner, J. A.—Eleventh Rep. ae N. Y., pp. 145-151.

1901. Britton, W. E.—Twenty-fourth Rep. Conn. Agr. Exper.
Sta., 1900; p. 314.

CLoveR LEAF-MIDGE
Dasyneura trifolii Low
(Cecidomyta trifolit)

This midge deserves some attention on account of its conspicuous
effects on the leaflets of white clover, the leaflet being folded in halves
along the midrib to form a sort of pod, which turns yellowish and at
length brownish. Within this pod can be found white or orange mag-
gots, or silken cocoons. The maggots change to minute flies—-so small
and inconspicuous as to interest only a specialist.

The economic importance of the leaf-midge is small, however,
and nothing has been added to our published knowledge of the species
since Comstock’s account of 1880. Some new information appears in
the present paper.

The species, long known in Europe, has been recorded from
Washington, D. C.; it occurs also in Illinois, and in all probability is
present in many other parts of the country.

Food Plants ——The leaf-midge feeds on white clover. In Europe
it has been said to affect the undermost root-leaves of red clover, but
I have not as yet been able to find it on that plant in this region.

The maggot does not fold the leaflet; the egg is laid before the
leaflet has opened out, and after the larve begin to work the leaflet
remains closed. It grows to a normal size, however, (PI. II., Fig. 4)
and continues to be green for a time, but eventually turns yellowish
near the midrib, where the leaflet bulges out here and there, blisterlike.

100

As the gall gets older the blistered areas become specked with brown,
and finally the entire gall turns brown and the leaflet dies. Inside the
pod are the maggots—white or orange, according to age—and the
- white cocoons. The eggs are to be found only between the folded
halves of the smallest leaflets, near the ground.

An affected leaflet continues to grow, and its forage value is
scarcely diminished, but its death is hastened a little by the maggots.
There is no effect upon the plant as a whole; when only one leaflet of
a leaf is affected by the insect, the other two remain healthy for an in-
definite time, but all three will at length wilt and die a little pre-
maturely.

It can hardly be said that this insect actually injures white clover,
taking everything into consideration.

Stages.—The egg has not been described before. It is like that of
many other common midges, being elliptico-cylindrical with a slight
curvature, colorless and translucent when laid, but showing an internal
red spot on the second day—not before—and becoming pale orange in
color. Length, 0.3 mm.; width, 0.075 mm.,—on an average. Several
eggs are laid, side by side usually, as in Plate II., Fig. 5, in which the
variation in the length of the eggs is to be laid to the midge instead of
to the artist.

The newly born larva is colorless and transparent, and 0.27 mim.
in length; scon it becomes white ; when old it is orange (PI. II., Fig. 6),
and when full grown its length is 1.5 to 2 mm. The skin is coarsely
granulate. The spiracular tubercles are arranged precisely as in the
larva of the clover seed-midge—in fact, this arrangement is the same
in several species that I have examined. The form of the sternal
spatula (Pl. II., Fig. 7) is, however, different from that of D. leguminic-
ola, the only species likely to be confused with this one as it occurs on
clover.

The cocoon is oval in general outline, and 1.5 mm. long. Often
it is flattened a little from contact with the leaflet or with other co-
coons.

The pupa, orange in color, has a darker median ventral stripe, and ~

blackish eyes, as Comstock says. The anterior border of the pro-
thorax is deeply notched, and there are two long, excurved, meso-
thoracic horns.

Comstock gave a translation of the original description of this

midge, which need not be repeated here. Rearing the midge from ~

white clover, there is no difficulty in determining the species. Catch-
ing it on the wing, the leaf-midge needs to be distinguished from the
seed-midge, which it resembles. Figures 3 and 8 of Plate II. show the
differences between the two species. The leaf-midge (Tig. 8) is the
smaller of the two, the female measuring 1.6 mm. in length. Both
species have the red abdomen, but the dorsal bands of black scales are
much larger and denser in frifolii than in leguminicola, and the scales
do not rub off so easily, so that the abdomen in the former species is
usually blackish. In addition, the leaf-midge has 14 or 15 antennal

101

segments, as against 16 or 17 in the seed-midge. The male, distin-
guishable from the female by the large clasping organs at the end of
the abdomen, is also smaller than the male of the seed-midge.

Life History.—tThe podlike galls (Pl. II., Fig. 4) of the leaf-midge
are common on white clover thruout the growing season, during which
the insect in one or another of its stages can always be found in some
of the galls. Usually several stages in the development of the insect
are represented at the same time in a single gall. Frequently one to
six individuals inhabit the same gall, and there may be more; I know
of twenty eggs being deposited by a single female on one leaflet.
Larve from eggs laid at the same time do not all develop equally ;
some of them outdistance the rest, and when the gall 1s crowded with
the maggots, some of them die off in the competition for nourish-
ment.

The earliest date that I have recorded for the galls is June 21, at
which time larve and cocoons were present; thereafter | found the
species in various stages every few days up to October 5, on which
date larva were common. The latest eggs and larve are killed by the
frost, along with the leaves which they inhabit. This fact in connec-
tion with what we know about the habits of the species warrants the
inference that it probably winters in the cocoon, tho possibly as a fly.

My observations indicate four full broods a year in this place,
with scattering and ill-fated members of a fifth brood. Each genera-
tion requires about one month, on an average, for its development. In
the field the broods overlap enough to make their separation by field
observations a little difficult. Yet there are times when almost all the
galls are empty, indicating an interval between two broods, when the
species is represented almost entirely by winged adults. Thus, Au-
gust 14, 1903, when I examined a great number of recently made galls,
! found 85 without living contents, tho remnants of cocoons were
often present; 9 with cocoons (one to four in each instance) ; 2 with
full-grown or large larve; and 2 with larve that had just hatched.
Again, August 15, 1907, I opened several hundred of the galls and
found nearly all of them to contain cocoons or full-grown larve; only
one or two had white larve, and very many of the galls were empty,
tho not more than a month old. Thus a break between two genera-
tions occurred about August 15 in two years.

Eggs laid August 1 gave six larve, the flies from which issued
August 22; this is the shortest life history that I have found for this
species. The egg period is six days as a rule; thus, eggs laid August
13 (2:45 to 3:15 p. m.) hatched August 19 (at noon). The period
in the cocoon varies. From two cocoons made August 3, the imagines
emerged August 13; in several other instances, nine days was the
period. On the other hand, a larva that was making a cocoon August
5 did not give the adult until August 27.

Habits —The midges can be obtained simply by picking the galls
and keeping them on damp sand or cotton-wool. A better way, how-
ever, is to transplant such plants as bear the galls, because the leaves
do not keep fresh very long after being picked.

102

To get the eggs and the subsequent stages it is only necessary to
turn a lot of the midges loose on potted white clover under a lamp
chimney (the narrow cylindrical kind) covered at the top with net-
ting, making sure that the plant bears some young unopened leaves.
It is best, also, to cut off most of the old leaves, especially in order to
facilitate observation.

These little flies mate readily under such conditions, and lay eggs
freely, as I have several times observed. After coition, which may
not last longer than a minute, oviposition occurs within an hour or so.
The female either drops to the ground or alights on the plant and
walks downward. In either event she finds, after more or less explora-
tion, a young leaflet still folded in halves. Standing at the base of
this, she wriggles her long flexible ovipositor in between the two con-
tiguous faces of the leaflet as far as possible; at intervals a slight wave
of distention passes back along the ovipositor, indicating probably the
passage of an egg. Usually several eggs are laid'on the same leaflet—
sometimes a dozen or more. After many eggs are laid, the abdomen of
the female is noticeably smaller.

In some way the insect prevents the leaflet from opening out. The
larva is quite unable to fold a leaflet that has already spread out. If
placed on such a leaf the larvee cannot even hold on to it, and rolls off.
Like other midge larve, they require some tight crevice in which to
develop.

Like them also, the maggots of the clover leaf-midge are very
sensitive to moisture, contracting and becoming motionless when it is
dry, and resuming activity when it is moist. Dryness prolongs the
period of development and retards the emergence of the fly. The
long record just given of twenty-two days from cocoon-making to
emergence was due in some measure to dryness. The larva found
making a cocoon August 5, was put into a small glass-covered box and
pressed up against the glass by means of dry cotton-wool, so that |
could watch the process of cocoon formation under the microscope.
The larva spun for awhile, and then left its cocoon unfinished and
wandered about, but it was contracted and motionless August 6 to 11.
On the latter date the cotton was moistened, and soon the larva began to
wriggle about in all directions, away from the light, and kept this up all
day. Coming to rest again, the larva contracted without making a
new cocoon, and gave an imago August 27. The larva often pupates
without making a cocoon, if taken out of its gall.

The cocoon is evidently composed of silken threads, as Comstock
said. Under the microscope the thread can be seen to issue from the
mouth of the larva, which swings the fore part of the body to and fro
as it spins. This fact is mentioned to counteract the old statement
that the cocoon is an exudation around the body of the larva.

The leaf-midge is not without natural enemies. I have found the
larve and pupe of a chalcid in the galls among the midge larve. The
chalcid is not common; I found it in only 1 percent of the galls, out
of hundreds examined. The chalcid larva might hastily be mistaken

4

103

for one of the midge larve, as it has much the same size and color—
white or orange. Its body is not so blunt as that of the maggots, how-
ever, and tapers anteriorly. Furthermore, the chalcid larva is far more
active than a midge larva. While the latter wriggles about sluggishly
and aimlessly, the former wriggles along hurriedly, as if it had some
end in view. A few times I have seen a chalcid larva attack and feed
upon a maggot of the midge, it being predaceous instead of parasitic.
The chalcid becomes a naked pupa within the gall, among any of the
maggots that may have escaped its attacks.

The clover leaf-midge needs no discussion from the point of view
of control. Where the clover is frequently pastured or cut (as on
lawns) it is hard to find any signs of the leaf-midge.

Dasyneura (Cecidomyia) trifoli Low
1880. Comstock, J. H—Rep. [ U. S.] Comm. Agr., 1879, pp.
197-199.

CLOVER CALLIPTERUS
Callipterus trifolii Monell

This aphid is common in our clover fields every year, but has not
been destructive as yet. It is far less numerous than the large green
aphid, Macrosiphum pisi, and is not wide-spread and gregarious like
that species, but is scattered, and rather solitary in habit.

C. trifolu, as found on clover, will be recognized, generally
speaking, as a small yellowish green or yellow species with six longi-
tudinal rows of dark tubercles on the abdomen.

This species has received almost no mention in our literature,
largely because it has done nothing to attract attention. The material
which we studied was determined tentatively by me from the original
description, and positively by the author of the species, to whom speci-
mens were sent by Mr. J. J. Davis.

Callipterus trifolu was described from Washington, D. C., by
Monell, who found it again in Missouri. It is common in Illinois, and
is reported authentically from Iowa, Kansas, Minnesota, North Da-
kota, New York, Delaware, and Virginia.

Descriptions —The following descriptions, sufficiently detailed for
the recognition of the species, and supplementary to the original de-
scription, are adapted from manuscript descriptions made by J. J.
Davis, in cooperation with Monell.

The viviparous females (whether winged or not) are pale yellow-
ish green. Eyes dark red to brown. Antenne pale greenish basally,
dusky apically, faintly imbricate, and as long as or a little longer than
the body. Legs pale, dusky at the joints; tarsi blackish. Abdomen
with six longitudinal rows of dusky setiferous tubercles. Style globu-
lar; cornicles tubercular; both a little dusky.

In the wingless viviparous female (Pl. III., Fig. 5) the dark ab-
dominal tubercles bear conspicuous capitate hairs, and the length of
the female averages 1.6 mm.

104

The winged viviparous female (Pl. IlL., Fig. 6) has a row of ten
to twelve sensoria on the third antennal segment. Wings hyaline;
veins dark brown to black, narrowly bordered with brownish, with a
small brown patch at the outer end of each vein; basal half of stigmal
vein obsolescent; discoidals as in the figure. The abdominal tuber-
cles of the two inner rows are oblong, and each of them bears two fine
sete. The remaining tubercles, more or less circular, have each but
one seta. Average length, 1.4 mm.

The wingless oviparous female is at first pale yellow, but the ab-
domen (excepting the last two segments) becomes progressively
orange as the eggs develop in the body, and the orange color may
eventually extend over most of the thorax. Eyes black. The anten-
nz do not reach to the cornicles, and the third antennal segment has.
eight or ten circular sensoria. Hind tibize swollen, and with sensoria.
Dorsal abdominal tubercles essentially as in the winged viviparous
female. Average length, 1.8 mm.

In the winged male the head and thorax are pale olivaceous
green, and the,abdomen pale yellowish green, with conspicuous black
dorsal spots. Antennz black (excepting the first two segments) and
as long as the body, with sensoria as follows: 12-15 on segment
three; 2-4 on four; 3-5 on five. Wings essentially as in the female.
The large black oval setiferous spots of the abdomen fall chiefly into
four rows—two dorsal and two lateral, with scattered spots between
the former and the latter, on each side. Style and cornicles dusky.
Average length, 1.2 mm.

The absolute lengths of the segments of the antennz and legs, as
well as those of the cornicles, are, as in other aphids, too variable to
be of much importance as specific characters. The relative lengths
are more constant, however, and hence more important for the sys-
tematist. They appear from the following table, which consists of the
averages of many measurements made from Urbana specimens by J. J.
Davis and from types of Mr. Monell—made by himself.

C. trifolu

Antenne
Sareea ©
I TL SL ea View taN, VI
Wingless viviparous female .07 mm. .05) .51) 34 .31) .154+.16) .17 06
Winged viviparous female 07 Obs | woul | 2StG |) sS5 Peal = alg 13 06
Winged viviparous female,
Monell’s types 05 045|° 445) 5.319) 223 115-3 /

Wingless oviparous female — .07 05:)£:40'| .29%)\-.201 | -13-F 4 | .06
Winged male 06 (0155) “soph 30} .29 | .15++ 15 O4

The egg, hitherto undescribed, is much like that of any other
aphid in being elliptical, 0.57 mm. long, and 0.25 mm. broad, but has a
characteristic bright orange-color when recently. laid.

105

Life History, etc—This aphid winters as an egg in the vicinity
of Urbana, and I have found as yet no evidence that the female hiber-
nates. The course of the life history differs but little from that of
other aphids. The eggs produce viviparous females, and these con-
stitute the successive generations up to the end of the season, when
winged males and wingless oviparous females are brought forth vivip-
arously. In this species, a large proportion—if not the majority—of
the viviparous females are winged.

Beginning with a viviparous female which issued from the egg
March 27, Mr. R. L. Webster followed the successive generations
thru the season and obtained a maximum of nineteen, the final genera-
tion appearing October 18, in the insectary. The individuals of this
generation were still very small on November 11, and disappeared
thereafter. The more important of R. L. Webster’s observations are
given in the following table.

C. trifolu
eg Birth | Maturity Death Days to | Days of Number
ion mature | life of young
1 Mar. .27 Apr. 20 May 9 24 43 36
2 Apr. 21 May 3 May 21 12 30 21
3 May 6 | May 18 May 26 1D 20 34
+ May 15 May 30 June 12 15 28 25
5) May 30 _ June 7 June 19 8 20 46
6 June 7 June 15 June 21 8 14 25
a June 15 June 22 July 7 a PP) 55
So) june 24 July 3 July 3 9 | 9 13
OSH esl lyaS July 12 July 18 9 1S 13
SO) Solio as July 18 July 31 5 18 34
a pale kS) July 29 Aug. 3 . 10 15 23
Zee aly. 29 Aug. 5 Aug. 22 7 24 70
ioe ie Ate 5 Aug. 11 Sept. 2 6 28 75
14 Aug. 11 Aug. 21 Sepia! 10 29 60
15 -| Aug. 21 Ae 28 = eee Sept lle +) 7 21 36
16 | Sept. 10 Sept. 18 SEpte25 | 8 18 20
Tl e sSepts 19 Oct 2 Oct 9 | 13 20 6
18 | Octy.2 Oct. 18 ? | 16 40-++ ?
19 | Oct 1s ? ? | ? 24-- ?
: sins oe — zeteee
[NSPE ERS RE oid BIG EITCOR ca ee ee | a) 22 34.8

The averages are made from the first seventeen generations. The
number of young produced per day by one female ranges from none
to thirteen, with an average of 3.7; and the bearing period of the
female averages 12.1 days.

Comparing this table with that for M. pist (p. 70) slight differ-
ences are apparent in the length of life and the period before maturity.
These differences are of no weight, however, in view of the great
variability of both species in both these respects. A few more obser-
vations would have changed,one way or the other, these averages, which
are so nearly alike. The averages show, rather, that M. pisi and C.

106

trifoli agree essentially as regards the time from birth to maturity,
the bearing period, and the length of life, the number of generations
being essentially the same in both species. C. trifolii produces, how-
ever, only half as many young per day as M. pisi (3.7 young as against
6), and this difference serves to account for the relatively smailer num-
bers of C. trifolu in the field compared with M. pisi.

Wintered eggs hatched March 27, 28, and 29, according to our
notes.

On red clover, brought into the laboratory in November, and
grown, there were found, January 29, a large number of the
orange oviparous females, which laid eggs in profusion. The average
number of eggs in the abdomen of the mother is ten, as found by J. J.
Davis.

The fungus Empusa aphidis attacks this plant-louse thruout the
season, in damp weather, just as it does M. pisi; and many of the in-
sect enemies of the latter species attack C. trifoli also.

Callipterus trifoli maintains its existence every year, but has
always been a sporadic species.

Callipterus trifolit Monell.
1882. Monell, J. T—Can. Ent., Vol. XIV., p. 14.
1908. Davis, J. J—Ann. Ent. Soc. Amer., Vol. I., pp. 256-258.

CLOVER STEM-BORER

Languria mogardi Latr.

The stem-borer is of but secondary importance among the in-
jurious insects of clover; it has never been a pest, so far as I can
learn.

The slender yellow larva eats out the pith of the clover stem,
making a long burrow, with brown discolored walls. The entire de-
velopment takes place within the clover stem, and the adults fly abroad
as slender beetles with dark blue wing-covers, and red thorax and
head.

Tho the beetle is well known to collectors, scarcely anything has
been published on its life history since Comstock’s brief account in
1880.

Distribution—This species was originally described from North
America, and the genus Languria does not appear in the catalogs of
European beetles. In this country L. mozgardi has been reported from
Pennsylvania, the District of Columbia, Indiana, Illinois, Michigan,
Kansas, Nebraska, and elsewhere. Generally speaking, it inhabits the
middle and the southern states, some of the western states, and parts
of Canada.

Food Plants and Injuries——The clover stem-borer is by no means
limited to red clover and mammoth clover, but feeds also on the fol-
lowing plants, as C. M. Weed, Chittenden, and Webster found: wild

va

107

sweet clover (Melilotus alba), pink fleabane (Erigeron philadelphi-
cus), daisy fleabane (FE. ramosus), mare’s tail (E. canadensis), rag-
weed (Ambrosia trifida), coneflower (Rudbeckia lacimata), yarrow
(Achillea millefolium), oxeye daisy (Chrysanthemum leucanthe-
mum), thistle (Cnicus altissimus), wild lettuce (Lactuca canadensis
and L. floridana), bellflower (Campanula americana), nettle (Urtica
gracilis and U. dioica) and timothy (Phlewm pratense). Most of
these are Composite, it will be noticed, and nearly all are weeds.

Injury.—The beetles do not lay their eggs in seedling clover, but
find clover that is more than one year old and select only the larger
stems of that.

By autumn, red clover sown in spring has developed stems of con-
siderable size, and the beetles are present—but they do not lay eggs in
autumn, in my experience.

The larva, by eating the pith, hollows out the clover stem, making
a long burrow, the walls of which turn brown. By cutting stems
across, beginning near the ground, and looking at the cut ends, one
can see whether the pith is white and solid or whether it has been
eaten out by this borer. The larve eat usually nothing but the pith,
which happens to be the part that the plant can best afford to lose.

Comstock wrote, “While they do not kill the stem outright, they
gradually weaken it and eventually cause its destruction, having also,
of course, a very injurious effect upon the maturing of the seed.” Un-
doubtedly the insect is injurious, but it is not so injurious as might be
supposed. The loss of the pith may affect the nutrition of the plant
to some extent, since the pith contains reserve food-material in the
form of starch. The chief effect of the stem-borer is, however, a
mechanical one. The stems that are hollowed out fall to the ground
prematurely, tho not until they have attained a considerable size. One
can find the borers most abundantly in the large prostrate stems rather
than in the stems that remain erect. The plants that lodge carry
their flowers to the ground, become soiled with dirt, and are not easy
to mow. Mammoth clover, running far into the season, lodges badly
from the work of the borer; while medium red clover, if cut when it
should be, escapes practically all injury from this insect.

Rarely the borer occurs in a small soft stem and causes it to wilt;
for in such a stem the larva eats not only the pith, but also some of
the adjacent ducts, thru which water is conveyed up the stem to the
leaves. In old stems these ducts are too tough to be eaten by the
larva.

Were this insect more numerous it might gradually develop into
a pest of considerable importance. It is most common on clover, but
has to its credit the fact that it affects also a considerable number of
weeds.

July 6 we found 41 percent of the old stems to be infested by
this borer. This was in the hay crop—as yet uncut. On the same
day we examined 61 new stems—the second growth after cutting—
and found two egg pits as the only signs of the borer. The beetles

108

had disappeared, almost without exception, by this date. July 7, 43
percent of the old stems, taken from many different places—roadside
as well as field—contained the insect. 3

Stages—The beetle (Fig. 23) is conspicuous on account of its
slender form, dark blue wing-covers, and shiny red head and thorax.
Length 4 mm. to 7.8 mm. In Languria mogardi, as distinguished from
other species of the genus, the antenne are black, with the club five-
segmented; the legs are red, with the outer half of the femur black
and the tibiz and tarsi often more or less dusky; last three abdominal
segments black, the abdomen otherwise red; elytra rounded at apices,
not sinuate, punctate-striate with the interspaces impunctate ; scutellum
red; head and thorax sparsely punctate.

Fre. 23. Fig. 24,

Clover Stem-borer, Languria mozardi: Fig. 23, beetle, greatly enlarged; Fig. 24, egg,
in natural position, four times natural length.

The egg (Fig. 24) is translucent cream-yellow, paler at each end,
elliptico-cylindrical and slightly curving, with one end slightly more
tapering than the other. One specimen was 1.5 mm, long and 0.3 mm.
broad ; another, 1.9 mm. by 0.5 mm.

The larva (Fig. 25) is slender, subcylindrical, 8 mm. long and 0.9
mm. wide when full grown, and light yellow, with a pair of brown
curving anal hooks. The thoracic legs are well developed and there is
a single anal proleg. Comstock gives other details. At birth the larva
is 2 mm. long; when four days old, 3 mm.; nine days, 5 mm.; full
grown, as above.

The pupa (Fig. 26) is yellow, slender, has a large head, and is 6
mm. long.

109

Life History.—There is but one generation a year in this latitude.
Here the species hibernates as a beetle. We have kept it alive over
winter. It may also winter as a larva, as Chittenden found larve

Tce.

Fic. 26.

Clover Stem-borer, Languria mozardi: Fig. 25, larva; Fig. 26, pupa.
Both greatly enlarged.

remaining as such from November to April, in stems of ragweed. In
late winter and early spring the beetles are to be found in red-clover
fields under the rubbish on the ground. In spring they eat clover
leaves to some extent, but do no conspicuous damage, as they are
comparatively few. In May and June these beetles mate; by July
10, nearly all of them have died off; rarely does one of the wintered
beetles survive into August. Young larve are common in the clover
stems in the last week of June and early in July, for the most part;
tho eggs are not uncommon early in July, and occur, rarely, as late as
July 17. Larve of all ages are common in clover stems in July and
thereafter; pupze are most numerous about August 15; and the beetles
of the new generation emerge from the first of August up to the mid-
dle of September, if not later. After the autumn frosts the beetles
are to be found on the ground under the debris.

Such is the life history, in condensed form, for this insect in this
part of Illinois. Some details of importance follow.

Eggs laid May 19 hatched May 24; those laid July 14 hatched
July 17. The egg period was three days also in the case of eggs —
that hatched July 8, 9, and 10. Eggs were taken in large num-
bers in the field July 5, 6, and 7, at which time 20 eet of all the
large clover stems examined contained each an egg. In one field 41
percent of the clover stems, taken at random, fae eng pits July 6, with
either eggs or small larve present.

110

Beetles that had hibernated, died in the insectary July 5, 9, and
26, after having been kept there with proper food, etc., since winter.
By July 5 most of the beetles are gone from the fields; only a few
stragglers continue to live, there being a conspicuous break between
the last of the wintered beetles and the first beetles of the new gen-
eration. Larve, nearly or quite grown, and pupe are common in
old clover stems July 28 to August 7. About July 30 the larve are
three times as numerous as the pup; but after the first week in Au-
gust the latter exceed the former in number. The new beetles emerge
mostly thruout August and during the first half of September. In
the insectary they issued almost every day from August 3 to Sep-
tember 14, and one emerged September 20. Most of them have is-
sued by August 26, however. At that date the burrows are almost all
vacant, and the beetles are abroad in the field, feeding a little, seeking
shelter at every cold spell, becoming more and more sluggish, and .
finally dormant. Not until spring does the reproductive instinct
awaken.

Habits.—Oviposition occurs to some extent late in May and early
in July, but for the most part in June, and has been witnessed in the
daytime. The female gnaws a small pit on the stem of a plant, as
Chittenden and others have observed. On clover stems these pits can
be found easily. Unless freshly made, the pit is brown, in contrast to
the green of the stem; a pit that is green is less than twenty-four hours
old, and indicates, as a rule, the presence of an egg. The egg-pit is
shallow, oval or round in outline, and not more than one sixteenth of
an inch in length. In the center of the pit a minute linear or elliptic-
al slit opens into the pith. Upon cutting open the stem, the egg is
seen on the inner wall of the stem, often opposite the pit, but sometimes
as far from it as four to six millimeters. The female makes the pit
with her mandibles, then pushes the end of the abdomen thru the bot-
tom of the pit and into the pith, these operations taking eight minutes
in one instance and sixteen in another, as observed by E. O. G. Kelly.
Sometimes a female gnaws out a pit without laying the egg. In red
clover the eggs are laid singly, almost invariably, in my experience,
rarely two being found together. In another plant (Leucanthemum),
however, Mr. Girault saw at least fifteen eggs deposited in the same
nidus (Ent. News, Vol. XVIII., pp. 366, 367).

The egg-pits occur on the main stem of a red clover plant any-
where from three to twenty inches from the ground, averaging ten
inches, the old pits having been carried up more or less by the growth
of the stem. Fresh pits, especially those on small stems, are usually
not far from the ground.

The larva, feeding on the pith (Fig. 27), tunnels out the main stem
for sometimes two feet. If two larve occupy the same stem their
combined efforts may produce a burrow as long as thirty-two inches,
extending from the main stem out into one of the larger branches.
The largest larvee and the pupz (Fig. 28) are found usually at the
lower end of the burrow, an inch or two from the ground, the pupa

111

with the head upward. The beetle (Fig. 29) after issuing from the
pupa lingers in the burrow for a while, and then escapes by gnawing
a round hole straight thru the wall of the stem. These exit openings
are rather conspicuous.

Fic. 27. Fie. 28. Fie. 29.

Clover Stem-borer, Languria mozgardi: Fig. 27, larva, in clover stem; Fig. 28, pupa, in same,—
both twice natural length; Fig. 29, beetle, on clover stem, slightly enlarged.

Natural Enemies.—Comstock mentioned two parasites that he
found in the burrows of this stalk-borer: a small black chalcid, with a
dark naked pupa; and a yellowish ichneumonid, the pupa of which is
enclosed in a delicate white silken cocoon. C. M. Weed gave a figure
and made brief mention of such a chalcid. I have found the chalcid
—probably the same one—in considérable numbers by examining an
immense number of stems. The egg of the parasite is found beside
that of the stem-borer, and hatches a little later than the latter egg.
The chalcid larva bites into the Languria larva and feeds upon it as an
external parasite. Now and then the chalcid larva detaches itself
from its host, but finds the latter again whenever necessary. The
Languria larva dies; the parasite survives and becomes a naked pupa
in the burrow, from which the adult emerges by cutting a minute
round hole thru the wall of the stem.

Eggs, larve, and pupz of the parasite were most frequent in the
burrows July 6 to 8. The adult chalcids issued from July 11 to Au-
gust 5,—most numerously, however, in the last week of July. Au-
gust 26 nearly all the Languria burrows were empty, and the stems
showed the exits of the host and those of the parasite.

An ichneumonid cocoon taken in a Languria burrow by me Au-
gust 7 gave the adult August 11.

Neither of these species has been determined.

112

Control—tThe clover stem-borer has not yet attracted much at-
tention as an injurious insect. Such effects as it produces are not of
the violent sort which attract notice. For a time I was in doubt as to
whether the lodging of the plants was due in any degree to this in-
sect; later, I found that affected stems do not lodge until they get
large, but then fall sooner than unaffected stems.

Every year the farmer unknowingly kills off large numbers of
these insects when he cuts his hay crop, whether he cuts it early or
late, for in the latter part of June and thruout July in this latitude
the great majority of the insects are inside the clover stems as larve
or pupe. The old beetles from the previous year are practically gone
by July 5, and the new beetles do not issue from the stems until about
the first of August. If the cutting of the hay crop is neglected, how-
ever, and left far into July, much of the clover will be flat on the
ground from the work of this insect. I had this tested on the uni-
versity farm, and when the clover was cut, heard, from the man who
mowed the field, certain appropriate comments upon the amount =

clover which had lodged.

If the red clover is cut when it should be—to make. the best ae
der—only about three stems in one hundred of the new growth will
show the insect. To find many larve in July and early August one
has to search in uncut field-clover, or in clover growing wild on the
border of a field or by the side of the road or the railroad track. The
practice of mowing and destroying volunteer clover is well worth the
little time that it takes.

Languria mozardi Latr.

1880. Comstock, J. H—Rep. [U. S.] Comm. Agr., 1879, pp.

199, 200.
1881. Lintner, J. A.—Fortieth Rep. N. Y. State Agr. Soc., 1880,
pp. 18-20.
1890. Weed, C. M.—Amer. Nat., Vol. XXIV., p. 867.
Weed, C. M.—Bull. Ohio Agr. Exper. Sta., Sec. Ser., Vol.
III., No. 8, pp. 235-238.
Chittenden, F. H.—Insect Life, Vol. IL., pp. 346, 347.

CLOVER SITONES
Sitones flavescens All.

This small brown curculio eats the leaves of clovers and alfalfa,
and its white footless grubs feed at the crown or at the roots of the
same plants. It has rarely been reported as injurious in this country,
but needs to be watched, nevertheless.

The species is abundant in the Atlantic states, especially near the
seashore, is on record from Indiana, Illinois, Iowa, and Minnesota,
and doubtless has a much wider distribution. Everything indicates
that it came from Europe, where this and other species of the genus
are injurious to clover and lucerne (alfalfa).

113

Food Plants and Injuries —White clover, alsike, red clover, and
alfalfa are known to be eaten freely by this insect. In Europe
another food plant is the grass Poa annua. Webster found a strong
preference for white clover and alsike over red clover in Indiana.
Osborn and Gossard found red clover to be eaten readily in Iowa.
Here in Illinois red clover is commonly eaten, but white clover shows
rather more of the injury. Alfalfa is also eaten to some extent. The
beetles eat at the edges of the leaves, and the larve feed at the roots
or the bases of the stems.

The leaves are bitten out in a characteristic manner, on acount of
the methodical feeding habits of the beetle. On an expanded leaflet
the beetle eats inward from the margin, making a small hemispherical
or U-shaped gap. The symmetrical injury, shown in Figure 30, is, how-
ever, frequent, as the beetle often, if not usually, selects a young
tender leaflet that is still folded in halves along the midrib, and notches
out both margins at once; or it may bite out a hemispherical notch at
the midrib, resulting in a round hole when the leaflet opens. When

Fic. 30.—Leaves of white clover showing
characteristic injury by beetle of Sitones
flavescens. Natural size.

all three of the folded leaflets are as
yet side by side, the beetle at one
operation produces the effect shown
ieneleatcatsthe lettem Higure 30:
A single notch constitutes a meal,
whether the beetle happens to eat one py. 31.—Sitones favescens. Greatly
thickness of the leaf or six. enlarged.

The youngest larve work at the
bases of the stems or the bases of the roots, tho most of the injury by
them is done on the roots. A few of these larve, biting out the roots
near the crown, can cause a plant to wilt, even tho no other insect is
present.

Aside from the serious injury done to white clover and the. at-
tacks upon alsike in Indiana in 1885, as reported by Webster, this
species has not put itself on record as an injurious insect in this

114

country. In Europe, however, it has now and then shown what it is
capable of doing in the way of damage.

Stages.—The beetle (Fig. 31) is a small dark brown or rusty
brown curculio, 5.5 mm. in length, with the beak short and broad. It
is distinguished from other species of the same genus by the absence
of erect sete on the interspaces of the elytra, and by its minute, nar-
row, hairlike scales. On fresh specimens the pronotum shows a pale —
median dorsal line and a pale stripe on each side, the lateral stripes
being continued forward on the head, above the eyes, and along the
beak; and also backward on the elytra for a short distance.

In the genus Sitones, of which we have several species that are
potentially injurious, the mandibles are stout, convex on the outside,
and roughly punctured; and the antennal grooves extend forward to
the bases of the mandibles,—not to mention other characters given by
Le Conte and Horn, and also by Casey. As in other Curculionide, the
male has one more “dorsal segment” than the female, owing to the
division of the pygidium into two segments.

The egg is subspherical, yellowish white at first, turning greenish,
and becoming black in two or three days. The diameter is nearly 0.4
mm., tho the egg is a trifle longer than broad.

The larva, 5 mm. long when full grown, is a stout, yellowish
white, footless grub. The head is small and yellowish brown, with
whitish lines. Body segments a little larger than the head; the second
and the third a little larger than the first. The legs are represented by
fleshy double tubercles. The abdominal segments gradually decrease
in size and bear longer hairs than the thorax, these being longest on
the small ninth segment, which terminates in a short, stout, truncate
pseudopod.

The larve assume a hooklike position, as mentioned by Webster,
the head and thorax making almost a right angle with the abdomen.

The pupa, 5 mm. in length, is pale yellowish, bearing hairs,
spinules, and tubercles. The abdomen gradually diminishes in size, and
the segments bear a few short reddish spinules, transversely arranged ;
the ninth segment has also two long, slender, converging lateral spines,
whitish basally and reddish apically, and toothed near the middle.
The pupa and the larva have been described in minute detail by
Xambeu.

Life History.—Scarcely anything on the life history of this spe-
cies has appeared in our literature since Webster’s useful article of
twenty years ago. In central Illinois the general course of the life
history is markedly like that of the clover leaf-weevil. There is one
generation each year. The beetles live thru summer and autumn, and
try to hibernate. The eggs are not laid until late in the season, but
they hatch in the same season and the little larve hibernate.

March 23 I saw the characteristic signs of the beetle on one red
clever leaf, recently expanded, and again March 28, on white clover.
The beetles are rare, however, in spring, and the earliest record that

115

] have of actually finding the beetle is June 19. This may have been—
and probably was—one of the new brood, the adults of which are not
uncommon in the last week of June and become common by the middle
of July. They emerge over a considerable period, as our records
show, our dates of emergence being July 10 and 16, and August 20 and
25. The pupal period is two to three weeks. Thru July, Au-
gust, and September the beetles are common in the field, where we
have found them as late as October 8, 14, and 31, and November 25;
and indoors, they may be kept alive far into the winter and doubtless
until spring. Like the clover leaf-weevil, these other curculios feed
for a long time before mating and laying eggs. Dates of coition are
July 1 (exceptionally early) ; August 26, 30, and 31; September 1, 8,
10, 15, and 27; October 10, 18, and 25; and November 14. All these
records except those of September 8 and 10 were made in the insec-
tary (unheated but yet affording some protection from frost), and out-
of-doors mating and oviposition would not occur for quite so long a
time. ‘Two to ten days elapse between coition and egg-laying. In
the field most of the eggs are laid in September. Indoors we have
found them to have been laid September 12, 14, 15, 19, 20, 22, 25, 26,
2/, and 29; October 23 and 27; and November 1, 2, 3,-4, 5, 10, 14, 16,
17, and 23. For several years we have kept the beetles in abundance
under daily observation thruout their long lifetime, without getting
other dates of oviposition than these. A single female lays her eggs
at irregular intervals extending over several weeks. Thus a female
which copulated October 25 laid eggs October 27, November 2, 10, 17,
and 24. The egg period varies, even under conditions apparently the
same, and ranges from 13 to 32 days. Hatching occurred in the in-
sectary from October 17 to November 29, mostly in November, and
most of it before winter. Not a few eggs, however, failed to hatch in
autumn, and did not hatch the following spring, when they were
evidently dead. There remains, nevertheless, the possibility that some
eggs survive the winter.

The species winters chiefly as a young larva, but occasionally sur-
vives as a beetle in this region.

Webster dug up frozen clover sod on December 9, at Lafayette,
Ind., and found therein, after thawing it out, Sitones larve, some of
them 1 mm. long, most of them under 2.5 mm. in length, and two
full grown and in earthen cells. He found also two beetles, but no
pup. One of the adults was still alive February 18. April 13 he
found in the field, larve (less numerous than in December, and in
about the same stage of growth), no pupe, and two beetles, which died
soon afterward. May 25 he obtained larve (less numerous than in
April, but now nearly or quite full-grown) and pupe, and a single
adult, which died May 30. These beetles laid no eggs. June 14 he
found several adults. I regard these as belonging to the new brood.

Webster’s account serves almost exactly for the species as it oc-
curs here in Urbana. He found, however, that eggs laid October 17
and 25 hatched in about 48 hours at a temperature of 65° F.—a much

116

shorter period than any that we have as yet found. He notes eggs as
being laid as soon as August 7, and copulation as occurring in the field
as late as November 12.

Habits—One or two beetles manage to live over winter, and even
to eat a little in early spring. Probably they issued late in the pre-
vious season and had enough vitality to carry them over to the next
season. I do not believe that such beetles lay any eggs in spring, how-
ever, in this locality.

When the larve emerge from the egg in autumn they feed on
tender green tissue down where the stems join, avoiding the light and
biting out little crevices, in which they lie. As it gets colder, they
go down deeper and reach the roots. The larger larve and the pupe
are found on the roots, and part of the eggs are laid there, some of
the female beetles, after copulation, burrowing down along the roots.
Other females, in the breeding-cage, drop their eggs promiscuously.

The beetles, like the larvz, avoid bright sunlight. Most of them
feed by night. Some feed, to be sure, in the daytime when the sky is
overcast, or even in bright daylight on a shaded portion of a plant.
To find many of the beetles during the day, however, one must scrape
away the rubbish on the ground near clover plants that show the
characteristic work of the insect. The beetles when exposed to the
light are quick to recover their wits, and to hurry off to another shel-
tered situation.

The beetle when engaged in feeding stands astride upon the edge
of a leaflet and stays in the same spot, swinging its head and thorax
up and down as it eats, and biting out a rounded gap always of about
the same form and size. ‘The beetles are alert when feeding, and drop
to the ground without hesitation when approached incautiously. In-
doors they will feed in the daytime if the light is not too strong.

Control—No enemies of this species have been found up to the
present. Should it become destructive it would be hard to deal with.
The cutting of the hay crop has little or no effect upon the larve or
the beetles; the former continue to feed on the roots, and the latter
feed temporarily on the green stubble and attack the new leaves as
soon as they appear. In a field of red clover cut July 1, I found the
beetles and larve common July 15; on clover cut July 23 the new
ieaves showed considerable injury July 30.

Fortunately it is not necessary as yet to prescribe remedies for
the attacks of this weevil.

Other Species of Sitones——In Europe several species of Sitones

are injurious to clovers and allied plants. In America we have at least
‘four of the European species, namely, flavescens, tibialis, hispidulus,
and lineellus. Tibialis is of no economic importance here. Hispidu-
lus, according to Schwarz, is a recent importation. It was first no-
ticed in 1876 in New Jersey, and subsequently in New York, Mary-
iand, and Pennsylvania. The species is injurious in the old country
and may become a pest here. Schwarz found it to be abundant in
1889 in Washington, D. C., feeding on red clover.

—

117

Lineellus is another potential pest, having injured clover and
alfalfa in Europe, tho it is not common here as yet. In Urbana, it
occurs occasionally in red clover fields, and the beetle eats the leaves
of that plant. A female taken November 26, 1907, by Mr. R. D.
Glasgow, a student at the University of Illinois, was kept alive on
clover leaves for a long time, under daily observation, and laid
eggs, eight being found November 27, and 10 on November 30. These
are oval, pale translucent yellow when laid, becoming jet-black; sur-
face minutely granulate; length, 0.5 mm.; breadth, 0.38 mm. Five of
the eggs found November 27, and laid not before November 26,
hatched December 16. The larva at hatching is white, stout, and
footless, with a black head, and its length is 0.82 mm. The body is
wrinkled to such an extent as to obscure the segmentation. The larva
is like that of flavescens,
and bends the head and
thorax over in the same
manger. hese larvze
fed readily on red clover,
digging into the bases of
roots or stems. :

To these few but new -
notes on the life history
is added a sketch of the
newly born larva of line- Fic. 32.—Larva of Sitones lineellus at hatching.
ellus (Fig. 32); Greatly enlarged.

Sitones flavescens All.

1887. Webster, F. M.—Rep. [U. S.] Comm. Agr., 1886, pp. 580-
582.

1890. Schwarz, E. A.—Proc. Ent. Soc. Washington, Vol. I., pp.
248-250.

1891. Osborn, H., and Gossard, H. A.—Bull. No. 14, Iowa Agr.
Bxpetrsstay pp. 77,178:

1896. Xambeu.—Mceurs et Métam. d’Insectes, Mém. 5, pp. 130-
135, Ext, Ann. soc: linn. yon, Vol. XLII: pp.
152-155.

CLOVER-ROOT MEALY Buc

Pseudococcus trifolu Forbes
(Coccus trifolu, Dactylopius trifoli)

This root-feeding mealy bug must in future be counted among the
insects that kill clover plants. Its capacity in this respect has been
overlooked, few entomologists having paid any attention to this incon-
spicuous subterranean species.

The insect occurs near the crown of the plant, as a plump oval
sluggish mealy bug, with more or less of a white coating. It sucks
the sap of the root by means of a minute beak. Legs and antennz

118

are present, but are very small. Almost always the bugs are found in
groups composed of individuals of various sizes, the largest being 2.5
mm. in length. Usually, also, these mealy bugs are accompanied by
ants.

As yet we know of the presence of this species in New York,
Delaware, Illinois, Michigan, lowa, and Kentucky only, but may
safely assume that it occurs in many other states.

This coccid is common on both red and white clover, and has
been reported from the sugar-beet by R. H. Pettit.

Tho these mealy bugs may be found in moderate numbers on the
roots of plants that appear to be healthy, the easiest way to find them
is to examine clover plants that are more or less wilted. Unaided by
other insects, the mealy bug’ often kills the clover plant. At first a few
leaves droop; then as these wilt and die other leaves droop, until
finally all the leaves are dead. No new leaves come forth. With
sufficient rain, however, the plant revives if not too far gone. On the
other hand, drought intensifies the effect of this sap-sucking insect.
Furthermore, the plant may suffer at the same time from the root-
borer, the leaf-weevil or the clover-louse, or from disease, old age,
poor soil, overpasturage, etc.

A certain proportion of the larve go from the roots to the leaves
to feed, and may cause the leaves to turn yellow and to die.

The fact that the injury from this insect is not wide-spread is ac-
counted for by the feeble ability of the wingless females to go from
one place to another, and the habit of the somewhat more active larve
to stay on the same plant. I have never found the species on first-
year red clover, tho its occasional occurrence on such clover might be
expected; the spread of the insect is very gradual; second-year clover
is affected in a sporadic way, except in a few localities where the in-
sect has obtained a foothold; and the worst injury is done to clover,
either volunteer or cultivated, that has run for more than two years.

Stages.—The winter female was described by Forbes as follows:
“The body is elliptical, broadly and equally rounded at both ends,
nearly circular in transverse vertical section, distinctly segmented ;
surface covered with waxy bloom, smooth except for a few small
hairs at the anal extremity. Feet, eyes, and antenne minute. The
body is .11 of an inch long, a little more than half as wide, and a little
less than half as deep; the abdomen decidedly shorter than the head
and thorax; the antenne .006 of an inch long, their length less than
the distance between their bases, obscurely seven-jointed [Fig. 33, a];
the first joint as wide as long; the second a little shorter and much
narrower than the first; the third and fourth a little smaller than the
second and not distinctly divided; the fifth and sixth distinct, equal
in length, and about equal to the first; the seventh long, cylindrical,
equal to the two preceding, obtusely pointed at tip. Entire antenna
minutely sparsely hairy under a high power. Eyes simple, consisting
of a single ocellus and a black speck on the side of the head, directly
behind the antenna, the third joint of which will about reach them.

a

a

119

“Legs .01 of an inch in length, each reaching about one half way
to its fellow of the opposite side. Tarsus one-jointed, as long as the
tibia, tapering regularly, terminating in a single stout curved claw;
tibia and femur of about equal length; trochanter as long as the coxa.
Legs very minutely sparsely hairy throughout. Rostrum very minute, in
the form of a thick tubercle projecting downwards in front of the
bases of the anterior legs, scarcely longer than wide, about half the
length of the femur.”

I may add, after a study of the types, that the bristle of each
caudal tubercle (anal lobe) is subtended by a pair of conical projec-
tions (Fig. 34,a); the anal ring bears six long bristles; the tarsal
digitules are four in number and knobbed, as in Figure 35; and the
claw bears no teeth. The largest of the types is 2.5 mm. in length.

b

Fic. 33.—Antenne of Pseudococcus trifolu: a, winter female; b, summer female;
c, larva. Greatly enlarged.

The summer female has been described by G. C. Davis and by R.
H. Pettit. The latter author writes: “The adult female measures a
little more than two millimeters in length, is reddish brown, in color,
covered with a coating of waxy or mealy secretion. The legs are dirty
yellow in color. From the sides project 15 to 17 (usually 17) waxy
processes, forming a fringe around the body in the usual manner,
with the shortest filaments near the head, and those near the tail con-
siderably longer, sometimes one third as long as the body. The anten-
ne [Fig. 33,b] are eight-jointed; joint one is swollen, as broad as
long; two and three are subequal, each about as long as one; four,
five, six and seven subequal, a little over half as long as two or three;
eight usually a little longer than five and six joined. There is consid-
erable variation in four, it is sometimes smaller than five, six or
seven, and sometimes slightly larger. The legs are dirty yellow, in
length the tarsus of hind leg is slightly more than half the tibia, which
about equals the femur. Digitules four; the two superior long and
slender, the two inferior shorter and more stout. (The digitules were

120

not distinct, but appeared as described.) Anal tubercles [Fig. 34, b]
not prominent, with a mass of small glandular spots, and bearing one
long hair, with some-
times several smaller
ones. Among the gland-
ular spots are placed two
conical projections or
processes on each tuber-
cle. These processes are
from two to three times
as long as broad at the
base. Derm dotted with
small round glandular
spots. Back, near the
caudal margin, spotted
with larger round gland-

Fic. 34.—Caudal region of Pseudococcus trifolii: a, win- Fic. 35.—Foot of Pseudococcus
ter female; b, summer female. Greatly enlarged. trifolti. Greatly enlarged.

ular spots.” Digitules and claws as described and figured by the
writer.

The larve derived from the winter females are from 0.69 mm. to
0.78 mm. long and half as broad as long at birth, and are elliptical
and flat, looking much like scale insects. The antennz are six-seg-
mented (Fig. 33,c). The minute structures of the caudal region are
essentially like those of the adult females, as in Figure 34.

The male, which G. C. Davis described, is a minute two-winged
insect, with two long white tail-filaments, two pairs of eyes, delicate
milky-white wings, and the body thinly covered with a white powder.
The head, thorax, and first two antennal segments are of a deeper red
than the abdomen, legs, and remaining antennal segments. The eyes
are dark reddish brown. A mouth is not evident.

The egg is elongate oval, 0.34 mm. long and 0.17 mm. broad,
translucent orange-yellow at first, becoming brownish yellow later,
and with a smooth surface. The egg-mass is surrounded by the cot-
tony secretion of the mother.

The winter females that I examined all had seven antennal seg-
ments; the grown larve, six; the full-grown summer females, eight;

reed

121

partly grown larve show the stages of transition from six to eight
segments. In young larve the division between segments two and
three is frequently obscure; in the large females the suture between
segments two and three, or three and four, is obscure.

Mr. Pettit, who studied summer females, intimated that the win-
ter specimens from which the original description was made were
male pupz. A study of the types, however, has shown me that they
are females, some of them being full grown, tho they resemble the
male pupz to the extent of having only seven antennal segments.

The necessity for using the name Pseudococcus for the genus
formerly called Dactylopius has been explained by Cockerell (Ann.
Mag. Nat. Hist., Ser. 7, Vol. IX., 1902, pp. 453, 454).

Life History.—The first account of this coccid was given by Dr.
Forbes, who found the species on the roots of white clover May 3,
at Normal, Ill. He found that the coccids “were protected by a
small yellow ant, Lasius flavus, in whose nests they occurred, and
were carried away by them like plant-lice when the nest was exposed.”

The general course of the life history has been made known by
G. C. Davis from his studies in Michigan. He found the coccids
abundant in clover fields April 27, and attended by Lasius miger.
When the nests of the ant were opened, the ants carried away these
coccids to another location. These were winter females. Davis put
some of them on potted clover and obtained young, the first appear-
ing May 15; these “gathered under the mother bug or collected in
the flocculent mass back of her that she had secreted while producing
them. They were of a light, translucent flesh-color, and much flatter
than the mother.”

The oviparous female makes a nest of waxy threads and places
therein 75 to 300 eggs. “At first she is large and plump, but, as
the pile of eggs increases, she decreases in size until at last there is
nothing left of her but a little dry wrinkled piece of lifeless skin, and
a mass of eggs back of her that will measure two or three times as
much as she did a short time before. The time required for the eggs
to hatch, and the young mealy bugs to reach maturity, is only about
six or seven weeks.”

The mealy bugs, tho numerous in the latter part of summer, dis-
appear in the fall, according to Davis, who failed to find them in any
stage October 15 where only a few weeks before they had been plen-
tiful. He suggested that they had changed to the winter form and
had been carried off by the ants.

Davis found also that the male, when about half or a third the
size of the full-grown female, crawls up to some part of the plant
above ground, spins a fluffy cocoon, and comes out, in less than a
week, as a winged adult.

In Urbana, the winter females of various sizes occur on the roots
of clover, attended by ants, in early spring. Our earliest dates are
March 24 and 26, but the females could doubtless be found thruout

ree

the winter. Small winter females taken March 28 and placed on the
roots of potted clover thrived until June 13, then disappeared.

Of the young brought forth on the roots by winter females, some
stay on the roots, but multitudes at once climb the stem of the plant
and fasten themselves by the beak to the under sides of the leaves.
These oval, flat, green, scalelike larvee may stay on the leaves for a
month or a little longer, growing meanwhile, or may go to the ground
sooner than that. One larva taken in the field May 25 and transferred
to potted clover stayed on the leaves until June 5, then disappeared,
to reappear June 9 down on the stem near the ground; there it re-
mained until June 27, when it moulted; July 5 it had disappeared for
good.

The young larve on the leaves I found to be common June 24,
July 5, and July 8; those of the first two dates were newly born and
had not moulted. Larvze on leaves June 24 were transferred to the
roots July 30, where they thrived thruout August.

These individuals above ground wander about as they get older,
and at length go to the ground, some dropping off the plant, perhaps
by accident, while others creep down the stem to the roots. This
migratory habit of the larve and their development on the leaves
have not heretofore been noted apparently. Very likely it will be
found that these aerial females are fertilized by the winged males.

While these individuals are feeding on the leaves there are others
of all sizes feeding in groups on the roots; in fact, the root-feeding
forms can probably be found every day in the year. The number of
generations has not been made out.

No eggs have been found in spring, and in our experience they
are not laid until late in the season. Our dates for oviposition in root-
cages are August 31, September 1, 2, 3, 5, and October 31. We
have taken eggs in the field August 31 and September 15 and 27.
The eggs always hatched before winter, the egg period being either 9
or 10 days in September, and 19 days for the eggs laid October 31.
The dates of hatching that we have noted are September 1, 2, 5, 10,
11, 12, 15, 18, 29, and November 19. The young from these eggs we
have carried far into the winter on clover roots, and regard them as
being the winter females, which are to attain their full growth in
spring.

Habits—The summer females wander about considerably on the
roots and often go above ground, to resume feeding at the base of the
plant in some crevice protected from the light, where they often lay
eggs.

As met with in the field, this mealy bug is almost always accom-
panied by ants, which have made their nest about the roots of the
clover plant. The species of ants found here, in this relation, are
Lasius flavus DeG., as mentioned by Forbes, and three other common
species: Lasius niger americanus Mayr, Lasius interjectus Mayr, and
Myrmica scabrinodis lobicornis Nyl.

123

This coccid can get along very well without the ants, however—
unlike the corn root-louse. In a root-cage the ants sometimes desert
the coccids, but the latter continue to feed and to produce eggs and
young as tho nothing had happened. In this instance the ants derive
most of the benefit from the partnership. When an ant finds one of
these mealy bugs on the ground or on the base of a plant, the ant
picks it up in its jaws, carries it down under ground, and deposits it
somewhere on the roots, usually not far from the base. If there are
eggs with the female, the ants carry these down also and put them on
rootlets.

When these coccids with ants and their cocoons are put on the
surface of the soil in a root-cage, the ants begin by burrowing down
along the roots. Then they carry down the coccids and the cocoons.
The former they place on the roots, but the latter they carry down
deeper to special chambers. If there are eggs of the coccid, the ants
show many attentions to them—touching them often with the tips of
the antennz, carrying them from place to place, and often cleaning
them with the mouth—in short, treating them as they do their own
eggs. The coccids are left much to themselves, but occasionally an
ant may be seen eating the white waxy secretion of the body of the
female. Mr. E. O. G. Kelly says that this secretion is eaten only
when it is newly made and fresh. Much of it is left by the ants and
is used by the female to cover her eggs.

In the field the coccid is now and then seen above ground at the
base of a plant-when no ants are present. Occasionally, also, the
coccids are found working on the roots without ants, there being
either no sign of ants or else a nest that appears to be deserted.

This coccid spreads very slowly, as has been said. Newly born.
-larve climb the stem to the leaves, but seem not to leave the plant to
any great extent, tho a few may be found on such neighboring plants
as are easily accessible. The summer females frequently go above
ground and wander about a little, tho they are sluggish. Probably the
species is spread by ants faster and farther than by any other means.

No natural enemies of this mealy bug are as yet known.

Up to the present the species has been of only minor economic
importance.

Pseudococcus trifolii Forbes.

1885. Forbes, S. A~—Fourteenth Rep.’State Ent. Ill., pp. 72, 73.

1890. Garman, H.—Second Rep. Ky. Agr. Exper. Sta., 1889,
pe 19520!

1894. Davis, G. C—Insect Life, Vol. VIIL., pp. 171-173.

Davis, G. C.—Bull. No. 116, Mich. Agr. Exper. Sta., pp.

56-60.

1899. Pettit, R. H—Can. Ent., Vol. XXXI., pp. 279, 280.

1902. Pettit, R. H.—Bull. No. 200, Mich. Agr. Exper. Sta., pp.
193, 194.

LITERATURE

GENERAL ARTICLES

1881. Lintner, J. A——The Insects of the Clover Plant. Fortieth
Ann. Rep. N. Y. State Agr. Soc., 1880, pp. 10-26. Sep-
arate, pp. 1-17.

1882. Saunders, W.—Insects Injurious to Clover. Ann. Rep. Ent.
Soc. Ontario, 1881, pp. 37-48. ;

1894. Davis, G. C.—Insects of the Clover Field. Bull. No. 116, Mich.
Agr. Exper. Sta., pp. 41-64.

1899. Hunter, W. D.—A Preliminary Report on Insect Enemies of
Clover and Alfalfa. Ann. Rep. Neb. State Bd. Agr., 1898,
pp. 239-285.

1902. Sanderson, E. D.—Insects Injurious to Clover. Insects Inju-
rious to Staple Crops, pp. 172-187.

Lists OF SPECIES

1881. Lintner, J. A.—Fortieth Ann. Rep. N. Y. State Agr. Soc., 1880,
pp. 13-15. Separate, pp. 46.

1889. Weed, C. M.—Bull. No. 1, Tech. Ser., Vol. I., Ohio Agr.
Exper. Sta., pp. 17-46.

1896. Cook, A. J—W. J. Beal’s Grasses of North America, Vol. I.,
pp. 370-395.

1899, 1900. Hunter, W. D.—Ann. Rep. Neb. State Bd. Agr., 1898,
pp. 240-247; 1899, p. 142.

EXPLANATION OF PLATE II.

Fic. 1 to 3.—Clover Seed-midge, Dasyneura leguminicola: Fig. 1, larva, ventral
aspect; 2, sternal spatula; 3, female midge. All greatly enlarged.

Fic. 4 to 8.—Clover Leaf-midge, Dasyneura trifolu: Fig. 4, galls on white clover,
also larve and cocoons, natural size; 5, eggs; 6, larva, dorsal aspect; 7,
sternal spatula; 8, female midge. Fig. 5 to 8 are greatly enlarged.

Fic. 9 to 11.—Clover Seed-caterpillar, Enarmomia interstinctana: Fig. 9, larva at
work in head of red clover, natural size; 10, larva, enlarged; 11, moth,
enlarged.

124

PLATE If.

PLATH III.

Fic. 1 to 4.—Clover-louse, Macrosiphum pisi: Fig. 1, winged viviparous female; 2, wingless
viviparous female; 3, aphid attacked by fungus, Empusa aphidis; 4, empty skin after
emergence of parasite—Aphidius.

Fie. 5 and 6.—Clover Callipterus, C. trifolii: Fig. 5, wingless viviparous female; 6, winged
viviparous female.

el a
2 viet :

~a5

INDEX

A

Acanthiide, 73.
Acarina, 73.

Achillea millefolium as food plant of Clover

Stem-borer, 107.

Adalia bipunctata as enemy of Pea-, or Clover-,

louse. 73. 74.

Aphids injurious to> Clover, 42.
Aphis-lion, manner of feeding, etc., 77.
Army-worm, 83.

Awbhitiry JenGeye oil.

Ashmead, W. H., 59.

Asopia costalis, 96.

ERRATA

Page 1, line 17, for a/éenus read niger.

Page 34, line 11, beginning with Ove dele as far as comma, substituting
The small yellow ant (Solenopsis molesta).

Page 37, last line, for red house-ant read small yellow ant.
Page 38, first line, for deézdis read mo/lesta.

Ireely Cate Vy Clover LeaI-Wweevlil, do.
injured by Clover Root-borer, 94.
injury to, by Clover Sitones, 113.
insects of, 41.

altissimus, Cnicus, 107.

Ambrosia trifida as food plant of Clover Stem-
borer, 107.

americana, Campanula, 107.

americanus, Lasius niger, 1 (see Errata), 27, 122. |

Rermlitus, 73; 74, 75, 80:
Syrphus, 73, 76.

annua, Poa, 113.

Anopedias error as parasite of Clover Seed-
midge, 50.

Ant, Carpenter-. See Carpenter-ant.
Corn-Field. See Corn-Field Ant.
small yellow, in nests of Corn-Field Ant, and

infesting corn hill, 34, 37. (See Errata.)

Ants attendant on Clover-root Mealy Bug, 118, |

7 122, 123:
aphidis, Empusa, 72, 82, 106.
Aphidius fletcheri as parasite of Pea- or Clo-
ver- louse, 73, 80.
washingtonensis as parasite of same, 73, 80.
sp. as parasite of same, 73, 79, 80.
dates of emergence of adults of,
80.

|
|

65.

Braconide, 73.

Sritton, W. E., 98, 99.

Bronson, E. V., 41.

bruchophagi, Tetrastichus, 58, 59.

Bruchophagus funebris, 50, 53-61. See Clover

Seed-chalcid.

generic characters of,

Bruner, Lawrence, 59.

Bumblebees in the clover field, 42, 43. 44.

Burdock as food plant of adult Clover Leaf-
weevil, 83.

Burning chaff and stems of Clover after hull-
ing as measure against Clover Seed-chalcid,
60.

on
+

Cc

Cabbage-worm, Common, as host of Empusa
spherosperma, 91.

Calcothion, effect of, on germination of seed-
corn tested, 11.

Callipterus trifolii, 103-106. See Clover Cal-
lipterus.

Campanula americana as food plant of Clover
Stem-borer, 107.

Camphor, effect of, on germination of seed-
corn tested, 11.

if
{

se et fl siren condor.

———— ee oe

=

INDEX

Acanthiide, 73.

Acarina, 73.

Achillea millefolium as food plant of Clover
Stem-borer, 107.

Adalia bipunctata as enemy of Pea-, or Clover-,
louse, 73, 74.

alba, Melilotus, 107.

Alcohols, effect of,
corn tested, 9, 13.

Alfalfa and Clover, the insect pests of, 41-124.

on germination of seed-

apparently immune from attack by Clover
Seed-midge, 47.
by Pea- or Clover- louse, 67.
as food plant of Clover Leaf-weevil, 83.

of Clover Root-borer, 93.
of Clover Seed-chalcid, 53.
or ‘Clover Sitowes, 112; 113.
insects, 41, 42.
Allograpta obliqua as enemy of Pea- or Clover-
louse, 73, 75, 76. ®
larva briefly characterized, 75.
parasite of, 76.
puparium of, 75.
Alsike as food plant of Clover Root-borer, 93.
Clover Seed-caterpillar reared from, 61.
Seed-midge reared from, 46.
freely eaten by Clover Leaf-weevil, 83.
injured by Clover Root-borer, 94.
injury to, by Clover Sitones, 113.
insects of, 41.
altissimus, Cnicus, 107. |

Ambrosia trifida as food plant of Clover Stem-
borer, 107.

americana, Campanula, 107.

americanus, Lasius niger, 1 (see Errata), 27, 122.
Perilitus, 73, 74, 75, 80.

Syrphus, 73, 76.

annua. Poa, 213. |

Anopedias error as parasite of Clover Seed-
midge, 50.

Ant, Carpenter-. See Carpenter-ant.
Corn-Field. See Corn-Field Ant.
small yellow, in nests of Corn-Field Ant, and

infesting corn hill, 34, 37. (See Errata.)

Ants attendant on Clover-root Mealy Bug, 118, |
AM W227 01236

aphidis, Empusa, 72, 82, 106.

Aphidius fletcheri as parasite of Pea- or Clo-

ver- louse, 73, 80.
washingtonensis as parasite of same, 73, 80.
sp. as parasite of same, 73, 79, 80.
dates of emergence of adults of,
80.

Aphids injurious to- Clover, 42.
Aphis-lion, manner of feeding, ete., 77.
Army-worm, 83.

thie dees ON

Ashmead, W. H., 59.

Asopia costalis, 96.

wo &

LBaccha fuscipennis, 7
Bassus letotorius, 73.

as parasite of Allograpta obliqua, 76.
of Syrphus ribesii, 76, 80.
parasite of, 76.
Beans as food plants of Clover Leaf-weevil,
42, 83.
Beet as food plant of Pea- or Clover- louse, 67.
Beetles injurious to Clover, 42.
Bellflower as food piant of Clover Stem-borer,
107.
bilineatus, Telephorus, 95.
bipunctata, Adalia, 73, 74.
Birds and barnyard fowls as enemies of Clo-
ver Leaf-weevil, 90.
Bisulfid of carbon for infested hay, 52,
bivulnerus, Chilocorus, 73, 74.
Bracon vernonie presumptive parasite of Clo-

he)

ver Seed-caterpillar, 65.
Braconid parasites of Clover Seed-caterpiilar,
65.
Braconide, 73.
Britton, W. E., 98, 99.
SroOMSOMe He Vee 4 le
bruchophagi, Tetrastichus, 58, 59.
Bruchophagus funebris, 50, 53-61.
Seed-chalcid.
generic characters of, 54.
Bruner, Lawrence, 59.
Bumblebees in the clover field, 42, 43. 44.
Burdock as food plant of adult Clover Leaf-
weevil, 83.
Burning chaff and stems of Clover after hull-
ing as measure against Clover Seed-chalcid,
60.

See Clover

C

Cabbage-worm, Common, as host of Empusa
spherosperma, 91.
Calcothion, effect of,
corn tested, 11.
Callipterus trifolii,

lipterus.
Campanula americana as food plant of Clover

Stem-borer, 107.
Camphor, effect of,

corn tested, 11.

on germination of seed-
103-106. See Clover Cal-

on germination of seed-

Camponotus ferrugineus, number of workers
in first-year colonies of, 29.
canadensis, Erigeron, 107.
Lactuca, 107.
Carabid larve as food of Corn-Field Ant, 37.
Carbolic acid, effect of, on germination of seed-
corn tested, 9, 13.
special test on reaction of Corn-Field Ant
tO; “225020
Carbon bisulphid, effect of, on germination of
seed-corn tested, 11.
carinatus, Tetrastichus, 50.
Carpenter-ant, number of workers in first-year
colonies of, 29.
time of appearance of winged males and fe-
males in colony of, 30.
Casey; <T.. L., - 114:
Caterpillars injurious to Clover, 42.
Cecidomyia leguminicola, 46.
trifolii, 99.
Cecidomyiide, 73.
cerasaphis, Pra n, 73.
Trioxys, 73, 80.
Chalcid larva as enemy of Clover Leaf-midge,
102-103.
parasite of Clover Stem-borer, 111.
parasites of Chrysopa cocoons, 78.
Chalcidide, 73.
Chalcids, phytophagous, 59.
Cheat infested by Clover Hay-worm, 98.
Chilocorus bivulnerus as enemy of Pea- or
Clover-louse, 73, 74.
of scale insects, 74.
Chittenden, F. H., 106, 109, 110.
Chlorid of lime, effect of, on germination of
seed-corn tested, 10.
special test on reaction
Ant to; 22; 23:
Chrysanthemum leucanthemum as food plant of
Clover Stem-borer, 107.
Chrysopa oculata, 77.

of Corn-Field

as enemy of Pea- or Clover-louse, 73, 78.
date of emergence of adult, 78.
parasites of eggs and cocoons of, 78.
plorabunda as enemy of Pea- or Clover-

louse, 73, 78.
date of emergence of adult, 78.
hibernation of, 77.
rufilabris, as enemy of Pea- or Clover-louse,
73, 78.
date of emergence of adult, 78.
Chrysopide as enemies of Pea- or Clover-
louse, 77-78.
Cicindela repanda probably an enemy of Clo-
ver Leaf-weevil, 90.
Clover, Alsike. See Alsike.
Clover and Alfalfa, insect pests of, 41-124.
citation to general articles insect
pests of, 124.
to lists of species of insect pests of,
124.

on

Xiv

|

Clover—Continued.

Callipterus, 103-106.
descriptions of different forms of, 103-104.
distribution of, 103.
life history of, etc., 105-106.
subject to attack by Empusa aphidis, 16.
tabular exhibit of average relative lengths
of segments of antenne of, 104.
of observations on successive genera-
tions of, 105.
comparison of above exhibit of,
with same for M. pisi, 105-106.
Crimson. See Crimson Clover.
field, beneficial insects of, 42.
fungous diseases of, 43.
Hay-worm, 42, 96-99.
control of, 98.
descriptions of different stages of, 97.
distribution of, 96.
injury by, 96.
life history and habits of, 97-98.
literature on, cited, 99.
moth obtained from dead grape leaves, 96.
reported from Cheat, mixed with Wheat
and Timothy, 98.
injury to, by insects, 41-43.
insect pests, number and control of, 45.
insects feeding solely on, 42.
Leaf-midge, 99-103.
and Clover Seed-midge distinguished, 100-
101.
articles on, cited, 103.
descriptions of different stages of, 100.
effect of dryness on development of larva
or, 102:
food plants of, 99-100.
galls of, 100, 101.
habits of, 101-102.
life history of, 101.
natural enemies of, 102-103.
oviposition of, 102.
Leaf-weevil, 43, 45, 73, 83-92, 118.
character of injury by, 83, 89.
cocoon of, 89.
control of, 92. ;
cooperation of, with Clover Root-borer, 84,
92, 93.
descriptions of different stages of, 84-86.
disease of, 84, 90-91.
distribution of, 83.
egg-period, length of, in autumn, 88.
European accounts of, 83.
food plants of and injuries by, 42, 83-84.
habits of, 88-90.
hibernation of, 88.
length of pupal period of, indoors, 86.
life history of, 86-88.
literature on, cited, 92.
locomotion of, 89.
natural enemies of, 90-91.’
oviposition of, 87-88, 89, 90.
variations in color of, 89.

Clover—Continued.
-louse, 42, 43,
Clover- louse.
Mammoth. See Mammoth Clover.
pollination of, 42, 43, 44.
Red. See Red Clover.
Root-borer, 42, 43, 92-96, 118.
and fertilizers, 95.
character, extent,
of injury by, 92.
control of, 95.
cooperation of,
84, 92.
descriptions of different stages of, 94.
distribution of, 93.
food plants of and injury by, 93-94.
life history and habits of, 94-95.
literature on, cited, 95-96,
natural enemy of, 95.
-root Mealy Bug, 42, 117-123.
ants attendant on, 118, 121, 122, 123.

66-82, 118. See Pea- or

and misunderstanding

with Clover Leef-weevil,

character of injury by, to Red and
White Clover, 118.

descriptions of different stages of,
118-121.

distribution of, 118.
habits of, 122-123.
reported from Sugar-beet, 118.
Seed-caterpillar, 44, 61-65.
control of, 65.
descriptions of stages of, 62-63.
distinctive markings of adult of, 61.
distribution of, 61.
food plants of and injuries by, 61-62.
life history of, 63-64.
literature on, cited, 65.
natural enemies of, 65.
rank of, as a pest, 61.
Seed-midge often present with, 62.
Seed-chalcid, 42, 44, 53-61, 64.
control of, 60.
descriptions of
distribution of, 53.
food plants of, 53.
habits of, 58-59.
hibernation of, 56.
injury by, 53-54.
life history of, 55-58, 60. P
possible source of confusion in study-
ing, 58.
summary of, 57.

stages of, 54-55.

literature on, cited, 61.
natural enemies of, 59-60.
aviposition of, 53, 58, 60.
seed-crop, early pasturing or cutting of clo-
yer important aid in securing good, 45.

influences and causes that combine to re- |

duce or prevent, 43-45, 60.
insects to which failure of, is often due,
44,

XV

Clover seed-crop—Continued.
ravages of Clover Leaf-weevil sometimes
favorable to, 45. (
Seed-midge, 44, 46, 53, 60, 61, 62, 63, 78.
and Clover: Leaf-midge distinguished, 100-
101.
character of injury to Clover by, 46.
control of, 51-52.
descriptions of different stages of, 47.
distribution of, 46.
effect of early cutting for, 51.
food plants of, 45, 46.
habits of, 49-50.
hibernation of, 48.
injury to Red Clover by, 50.
life history of, 48-49, 50.
literature on, cited, 52-53.
natural enemies of, 50-51.
oviposition of, 49.
proper date for early cutting and for mow-
ing back for, 51.
Sitones, 112-117.
control of, 116.
descriptions of different stages of, 114.
detailed descriptions of larva and pupa of,
cited, 114.
distribution of, 112.
food plants of and injuries by, 113-114.
habits of, 116.
life history of, 114-116.
literature on, cited, 117.
stacked or stored, injury to, 96.
Stem-borer, 42, 106-112.
chief effect of; on Clover, 107, 112.
control of, 112.
descriptions of different stages of, 108.
distinguished from other species of Lan-
guria, 108.
distribution of, 106.
food plants of and injuries by, 106-108,
110.
habits of, 110-111.
life history of, 109-110.
literature on, cited, 112.
natural enemies of, 111.
oviposition of, 110.
volunteer, always infested by Clover Seed-
caterpillar, 64.
by Clover Seed-chalcid, 60.
destruction of, 46, 52, 60, 65, 112.
White. See White Clover.
Wild Sweet, as food plant of Clover Stem-
borer, 107.
winter-killing of, 68.
Clovers, order of preference of, by Clover
Leaf-weevil, 83.
Cnicus altissimus as food plant
Stem-borer, 107.
| Coal-tar, effect of,
| corn tested, 11.
|

|
of Clover

|
|
|
|
|
|
|

on germination of seed-

-water. See Tar-water.

xvi

Coccinella novemnotata as enemy of Pea- or
Clover- louse, 73.
dates of emergence of, as a beetle, 74.
parasite of, 74.
sanguinea as enemy of Pea- or Clover- louse,
ist
date of emergence of, as a beetle, 74.
Coccinellide as
louse, 73-75.
dates of emergence of adult, 74.
food of, 74. j
predaceous enemy of, 74, 75, 80.
Coccus trifolii, 117.
Cockerell, T. D. A., 121.
Collops quadrimaculatus, larva of, as parasite
of eggs of Clover Leaf-weevil, 90. |
Colorado Potato-beetle, eggs of, eaten by Megil- /
la maculata, 74.
Common Flower-bug as enemy of Clover Seed- |
midge, 51.
Composite as food plants of Clover Stem-borer,
107.
Comstock, J. H., 50, 62, 63, 64, 65, 99, 100
LOZ LOZ Woe. lane :
Coneflower as food plant of Clover Stem-borer,
107.
confluens, CEcanthus, 73, 79.

enemies of Pea- or Clover-

Con Sol, effect of, on germination of seed-corn
tested, 11.
convergens, Hippodamia, 73.
Copper sulphate, effect of, on germination of
seed-corn tested, 11.
Corn-Field Ant, abundance and distribution of,
27).
adaptation of behavior of, to changing
conditions in field, 36-37.
and Corn Root-aphis, importance of con-
trolmoieale
single field experiment with |
lents for, inconclusive, 22.
area occupied by single colony of, 33. |
beginning of a new colony of, 28-30.
behavior of, w:thin the nest, 34-36.
contents of nests of, 27-28.
effect on, of change of crop from Corn
to Oats, 38-40.
eggs and young of
destroyed by, 32, 36.
food of, emergency and ordinary, 36-37.
injury to Corn by, 37-38.
insignificance of males in life of colony
Of 1055
intercolonial hostilities of, 31-33.
utility of, 32-33.
Lasius niger americanus, habits and be-
havior of the, 27-40.
nursing instinct of workers of, illus- |
trated, 35-36. |
relations of, to other species, of ants, 34. |
size of colonies of, 30-31.

repel-

Corn Root-aphis

Corn-Field Ant—Continued.
special tests of reaction of, to various
repellents, 22—23.
experimental, description of experiment in,
for practical test of effect of repel-
lents against Corn Root-aphis and
Corn-Field Ant, 13-21.
for practical test of effect of repellents
against Corn Root-aphis and its at-
tendant ant, 13-21.
general final result of above test in, 21.
insect infestation of, at time of plowing
for Corn, 14.
minor additional test in, with
repellents on seed-corn, 22-23.

various

repellents used in above experiments in,
14.
results of treatment of seed-corn evi-
dent in, at first and second inspec-
tions, 16-19.
of same evident in, at third inspection,

19.
of same evident in, at fourth inspec-
tion, 19-21.

injury to, by Corn-Field Ant, 37-38.
Root-aphis, 38.
experiments with repellents against,
and 1906, 1—26.
general program for prevention of injury
by, 24-26.
kerosene applied to seed-corn as measure
against, 2.
natural check on, 1.
power of multiplication of, 1.
repellents against, tested to determine ef-
fect on germination of seed corn,
3-13:
alcohols, 9, 13.
Calcothion, 11.
camphor, 11.
carbolic acid, 9, 13.
carbon bisulphid, 11.
coal-tar, 11.
-water. See tar-water.
Gon Sol, 11:
copper sulphate, 11.
crude petroleum, 8, 12.
formalin, 9, 13.
Fruitolin, 11.
iron sulphate, 11.
kainit, 10.
kerosene, 2, 4, 6, 7, 12.
emulsion, 4, 6.
lime, 10.
and sulphur, 10.
chloride of, 10.
sulphur, and blue vitriol, 10.
and salt, 10.
lysol, 9, 13.
musk, 11.
mustard, 11.

1905

8

xvii

Corn Root-aphis, repellents against—Cont.
oil of cloves, 8, 9.
of lemon and alcohol, 8, 12.
of sassafras, 8, 9.
of wintergreen, 8, 9.
salt, 10.
Scalecide, 11.
sulphur, 10.
tar-, or coal-tar-, water, 5, 6,
tobacco-water, 11.
turpentine, 5, 6.

11.

Root-worm beetles, dead, as food of Corn- |

Field Ant, 37.
Northern, 24.
costalis, Asopia, 96.
Hypsopygia, 96.
Pyralis, 96.
Crimson Clover and lime, 81.
injured by Clover Seed-chalcid, 53.

preferred to Red Clover by Pea- or Clover- |

louse, 67.
Crude petroleum, effect of, on germination of
seed-corn tested, 8, 12.
Curculionide, 86, 114.
Cutworms as food of Corn-Field Ant, 37.
cylindrica, Sphzrophoria, 73, 76.

D

Dactylopius trifolii, 117.
Daisy, Oxeye, as food plant of Clover Stem-
borer, 107.
Dasyneura leguminicola, 46-53.
and 1). trifolii distingu’shed, 100-101.
(See Clover Seed-midge.)
trifolii, 99-103. See Clover Leaf-midge.
Davis; G, G50, 52,94, 95. 119, 120; 121.
Davis, J. J., 41, 103, 104, 106.
destructor, Nectarophora, 66.
Diabrotica longicornis, protection against, 24.
dioica. Urtica, 107.
Diplosis sp. as enemy of Pea- or-Clover- louse,
73y 78: ;
hibernation of, 78.

E

Earthworms as food of Corn-Field Ant, 37.
Eggs of Aphidius sp., 80.
of chalcid, 111.
of Chrysopide, 77, 78.
of Clover Callipterus, 104, 105, 106.
of Clover Hay-worm, 97, 98.
of Clover Leaf-midge, 99, 100, 101, 102.
ot Clover Leaf-weevil, 84, 87-88, 89-90.
of Clover-louse. See eggs of Pea- or Clover-
louse.
of Clover Root-borer, 93, 94, 95.
of Clover-root Mealy Bug, 120, 121, 122, 123.
of Clover Seed-caterpillar, 62, 63, 64.
of Clover Seed-chalcid, 53, 55, 56, 57, 58,
AOeTG0s
of Clover Seed-midge, 47, 48, 49, 51, 52.

|

Eges—Continued.
of Clover Sitones, 114, 115, 116.
of Clover Stem-borer, 107, 108, 109, 110, 11L
of Coccinellide, 74.
of Colorado Potato-beetle, 74.
of Euschistus variolarius, 75, 77,
of Hippodamia parenthesis, 74.
of Megilla maculata, 74.
of Pea- or Clover- louse, 67, 69,

82.
of Podisus maculiventris, 75, 77.
of Sitones lineellus, 117.
of Syrphide, 75, 76.
Empusa aphidis and other natural agencies ef-
fective against Pea- or Clover- louse, 72,
82.
Clover Callipterus subject to attack by, 106.
life history of, 73.
spherosperma, 73. :
disease of Clover Leaf-weevil due to, 90-91.
distribution of, 91.
various hosts of, 91.

Enarmonia interstinctana,
Seed-caterpillar.

English Sparrow as enemy of Pea- or Clover-
louse, 80.

Entomophthora spherosperma, 91.

Erigeron canadensis, E. philadelphicus, and E.
ramosus as food plants of Clover Stem-borer,
107.

error, Anopedias, 50.

Eurytoma funebris, 50.

Euschistus variolarius as enemy of Pea- or

Clover- louse, 73, 79.
attacking Syrphide, 77, 80.
preying upon coccinellid pup, 75.

80.

WOvsaiy trae

61-65. See Clover

F

farinalis, Pyralis, 97.
ferrugineus, Camponotus, 29.
Fertilization to sustain Corn under Corn Root-
aphis attack, 25.
peas attacked by Pea- or Clover- louse,
81.
Fertilizers and the Clover Root-borer, 95.
for root-feeding insects, 95.
to lessen injury by Corn Root-aphis, 25.
Fielde, Adele M., 36.
flavescens, Sitones, 112.
flavus, Lasius, 122.
Fleabane, Daisy and Pink, as food plants of
Clover Stem-borer, 107.
Fletcher, James, 51, 76, 78, 80, 81, 95.
fletcheri, Aphidius, 73, 80.
Flies as hosts of Empusa sphzerosperma, 91.
floridana, Lactuca, 107.
Flower-flies in clover fields, 75.
Eolson, Ji \Ws, 37.
The Insect Pests of Clover and Alfalfa,
paper on, by, 41-124.
lorbes: S-A., 96, 98, 118. 121. 122.

Xvlil

lrormalin, effect of, on germination of seed-
corn tested, 9, 13.
special tests on reaction of Corn-Field Ant
£0), 22," 25%
Formica schaufussi inhabiting nests of Corn-
Field Ant, 34.
Fruitolin, effect of, on germination of seed-
corn tested, 11.
funebris, Brucophagus, 50, 53.
Eurytoma, 50.
Fungous disease pf Clover Leaf-weevil, 90-91,
92.
account of general course of, and
citations to technical details con-
cerning, given, 91.
prevalence of, 91.
fuscipennis, Baccha, 73.
Ocyptamus, 73, 76.

G

Garman, H., 28.

Geoica squamosa, 39.

Gilbert, Jacke, es

Gillette, C. P., 62.

Girault, A. A., 77; 110:

glacialis, Hippodamia, 73.

Glasgow, R. D., 88, 117.

Glypta leucozonata as parasite of Clover Seed-
caterpillar, 65.

Goldenrod flowers as food of adult
Leaf-weevil, 83.

Gossard, H. A., 62, 64, 65.

gracilis, Urtica, 107.

Grape, moth of Clover Hay-worm reared from
dead leaves of, 42, 96.

Grapholitha interstinctana, 61, 65.

Grass Root-louse on roots of Corn and weeds,
attended by Corn-Field Ant, 38.

Grasshoppers, dead, as food of Corn-Field Ant,

Si

injurious to Clover, 42.

Green Dolphin. See Pea- or Clover- louse.

Gryllide, 73.

Clover

H

Wart. Go vA. 7.9:
and Weed, C. M., 75.

Hay-worm, Clover. See Clover Hay-worm.

Hippodamia convergens, H. glacialis, H. pa-
renthesis, and H. 13-punctata as enemies of
Pea- or Clover- louse, 73.

hispidulus, Sitones, 116.

Honey-bees in the clover field, 42, 43, 44.

Hood; J.D. 79:

Hopkins, A. D., 53.

Howard, L. O., 41.

Hydrocyanic acid gas for infested stored hay,
99.

Hylastes obscurus and H. trifolii, 92.

Hylastinus obscurus, 92-96, See Clover Root-
borer.

Hylesinus trifolii, 92.

Hypsopygia costalis, 96-99. See Clover Hay-

worm.
|
/ I
Ichneumonid parasite of Clover Stem-borer,
111
:

parasites of Chrysopa cocoons, 78.
of Clover Seed-caterpillar, 65.
Ichneumon parasites of Phytonomus larve. 90.
Iclineumonide, 73.
Ichneumons as hosts of Empusa_ spherosper-
ma, 91:
Insect pests of Clover and Alfalfa, 41-124.
See Clover and Alfalfa.
insidiosus, Triphleps, 51, 73, 79.
| interjectus, Lasius, 122.
interstinctana, Enarmonia, 61.
Grapholitha, 61.
Iron sulphate, effect of, on
seed-corn tested, 11.
Isocratus vulgaris, 73.
as parasite of Bassus

J

germination of
letotorius, 76, 80.

| Janet, Charles, 28.
Jassids injurious to Clover, 42.
Johnson. WG, (66; 7276s, co. eas

K
Kainit, 95. .
effect of, on germination of seed-corn tested,
10.
Kaltenbach, J. H., 68.
Kelly, EO G:,>2,0148 195 21,7225 30, Folin ods
35, 38, 41, 69, 72, 78; 110, 123:
Kerosene, effect of; on germination of seed-
corn “tested; 254,56, 97, Le:
emulsion, effect of, on same tested, 4, 6.
to control Pea- or Clover- louse in gardens,

$1.
special test on reaction of Corn-Field Ant
£0, (225-23;

| Kilman, A. H., 83.
| Kirby, Wm., and Spence, Wm., 68.
|:Knab, F., 41.

L
| Lace-wing flies, or lacewings, 77-78.
laciniata, Rudbeckia, 107.

Lactuca canadensis and L. floridana as food
plants of Clover Stem-borer, 107.

Ladybirds and their larve as enemies of Pea-.
or Clover- louse, 73-75.

| latotorius, Bassus, 73, 76, 80.

Lampyride, 73.

Languria, 106.
mozardi, 106-112. See Clover Stem-borer.

| Lasius flavus attendant on Clover-root Mealy
Bug, 122. ri

in‘erjectus attendant on same, 122.

niger americanus, 1. (See Errata.)

|

a

=

Lasius niger americanus—Continued.
attendant on Clover-root Mealy Bug, 122.
the Corn-Field Ant, habits and_ be-

havior of, 27-40.
attendant on Clover-root Mealy Bug, 121.

laticinctus, Microdus, 65.

Leaf-hoppers as hosts of Empusa sphzrosper-

ma, iO.

Leaf-weevil, Clover. See Clover Leaf-weevil.

MeuGonte, J. L.. and Horn, G. H., 114.

leguminicola, Cecidomyia, 46.

Dasyneura, 46, 100.
Lettuce as food plant of Pea- or Clover- louse,
67.
Wild, as food plant of Clover Stem-borer,
107.
Leucanthemum as breeding plant of Clover
Stem-borer, 110.
leucanthemum, Chrysanthemum,
leucozonata, Glypta, 65.

107.

Lime and sulphur, effect of, on germination

of seed-corn tested, 10.
chlorid of. See under Chlorid.
effect of, on germination of seed-corn tested,
10.
special test on reaction of Corn-Field Ant
to; 22.23;
sulphur, and blue vitriol, effect of, on ger-
mination of seed-corn tested, 10.
and salt, effect of, on germination of
seed-corn tested, 10.
lineellus, Sitones, 116, 117.
Lintner, J. A., 61.
lobicornis,- Myrmica scabrinodis, 122.
longicornis, Diabrotica, 24.

Lucerne. See Alfalfa.
Lysol, effect of, on germination of seed-corn
tested, 9, 13.
M
Machrocheles meestus protected in. nests of
Corn-Field Ant, 36. ‘
Macrosiphum, 68.
pisi, 66-82, 103, 105, 106. See Pea- or
Clover- louse.
maculata, Megilla, 73, 74, 80.
maculiventris, Podisus, 73, 75, 77.
Mammoth Clover, 41.
and the Clover Seed-caterpillar, 61.

and the Clover Seed-midge, 46.
freely eaten by Clover Leaf-weevil, 83.
infested by Clover Seed-chalcid, 53.
injured by Clover Stem-borer, 107.
one of chief food plants of Clover Root-
borer, 93.
Mare’s-tail as food plant of Clover Stem-borer,
107.
marginatum, Mesogramma, 73, 76.
Matthews, W. C., 41.
May-beetles, dead, as food of Corn-Field Ant,
aa

xix

Mealy Bug, Clover-root. See Clover-root
Mealy Bug.
bugs in nests of Lasius niger americanus, 27,
Medicago sativa, 83. See Alfalfa.
Megilla maculata as enemy of Pea; or Clo-
ver- louse, 73, 80.
dates of emergence of, as beetle, 74.
food of, 74.
parasite of, 74-75, 80.
Melilotus alba as food plant of Clover Stem-
borer, 107.
Mesogramma marginatum and M. politum as
enemies of Pea- or Clover- louse, 73, 76.
date of emergence of adults above
species of Mesogramma, 73, 76.
Microdus laticinctus as parasite of Clover Seed-
caterpillar and its cocoons, 65.
millefolium, Achillea, 107.
Mite as enemy of Pea- or Clover- louse, 79.
commonly inhabiting nests of Corn-Field
Ant, 36.
meoestus, Machrocheles, 36.
molesta, Solenopsis, 34, 38 (see Errata).

of

Monell Jin.) 203,04:

Mosquitoes as hosts of Empusa sphzrosperma,
91.

mozardi, Languria, 106.

Muriate of potash, 95.

Murtfeldt, M. E., 65.

Musk, effect of, on germination of seed-corn
tested, 11.

Mustard, effect of,
corn tested, 11.

Myriapods as food of Corn-Field Ant, 37.

Myrmica scabrinodis lobicornis attendant on
Clover-root Mealy Bug, 122.

on germination of seed-

N
Nectarophora destructor, 66, 68.
Nettle as food plant of Clover Stem-borer,. 107.
of Pea- or Clover- louse, 67.
niger americanus, Lasius, 1 (see Errata), 27,
122.
Wastaisey UZ.
Nitrate of soda, 95.
Northern Corn Root-worm, protection against,
24.
novemnotata, Coccinella, 73, 74.

O
obliqua, Allograpta, 73, 75, 76.
obscurus, Hyalastinus, 92.
oculata, Chrysopa, 73, 77, 78.
Ocyptamus fuscipennis, 73.
presumptive enemy of Pea-
louse, 76.
CEcanthus confluens as enemy of Pea- or Clo-
ver- louse, 73, 78-79.
Oil of cloves, effect of, on germination of
seed-corn -tested, 8, 9. bat
of lemon and alcohol,
tested, 8, 12.

or Clover-

effect of, on same

Oil of iemon—Continued.
special test on reaction of
Ant to, 22, 23.
of sassafras, effect of, on germination of
seed-corn tested, 8, 9.
wintergreen, effect of,
of seed-corn tested, 8, 9.
Ormerod, E. A., 46.
Osborn, Herbert, 62, 64, 65, 97.
Osborne, J. A., 89.
Oxeye Daisy as food plant
borer, 107.

Corn-Field

of on germination

of Clover Stem-

B
Pachyneuron syrphi, 73.
bred from puparia of Allograpta obliqua
apparently parasitized by leeto-
torius, 76, 80.
panicola, Schizoneura, 38, 39.
Parasites or other enemies:
of Allograpta obliqua, 76.
of Bassus letotorius, 76, 80.
of Chrysopa eggs and cocoons, 78.

Dassus

of Clover Callipterus, 106.

of Clover Leaf-midge, 102-103.
of Clover Leaf-weevil, 90-91.

of Clover Root-borer, 95.

of Clover Seed-caterpillar, 65.

of Clover Seed-chalcid, 59-60.
of Clover Seed-midge, 50, 51.

of Clover Stem-borer, 111.

of Coccinella 9-notata, 74.

of coccinellid pupx, 75.

of eggs of pentatomids, 75, 77.

of Megilla maculata, 74, 80.
of
of scale insects, 74.
of Syrphus ribesii, 76.
parenthesis, Hippodamia, 73, 74.
parvus, Rhyncholophus, 73, 79.
Pea-louse, or Clover-louse, 66-82.
control of, 81-82.
descriptions of different forms of, 68-69.
distribution of, 66.
food plants of and injury by, 66-68.
generic names of, 68.
habits of, 71-72.
insects directly or
73, 80.
life history of, 69-71, 72.
literature on, cited, 82.
natural agencies effective against, 82.
enemies of:
parasitic, 79-82.
predaceous, 72-79.
rank of, as a pest, 66.
reproduction of, 72.
tabular exhibit of data on successive
generations of, 70.
on molting intervals of, 71.
Pea, Sweet, as food plant of Pea- or Clover-
louse, 67.

Pea- or Clover- louse, 72-80, 82.

indirectly aftecting,

XX

| Peas-as food plants of Pea- or Clover- louse,
42, 67:
of Clover Root-borer, 42, 93.

early, practically exempt from injury by Pea-
or Clover- louse, 81.
field, damage to by Pea- or Clover- louse,
| 66, 67.

flowering sweet, measure to protect against

Pea- or Clover- louse, 81.
garden, measure to protect against same, 81.

Pentatomide as enemies of Pea- or Clover-
louse, 73, 79.
Pergande, Theo., 68.
Perilitus americanus, 73.
as parasite of ladybirds, 74, 75.
dates of emergence of adult, 74.

Pettit, Rockies hoe. eltes WO. tee
Phanerotoma tibialis as
Seed-caterpillar, 65.

philadelphicus, Erigeron, 107.
Phleum pratense as food plant of Clover Stem-
borer, 107.
Phytonomus punctatus, 83-92.
characters distinguishing, from other spe-
\ cies of its genus, 86.
(See also Clover Leaf-weevil.)
| Pinkerton, Charlotte M., 41.
pisi, Macrosiphum, 66, 103, 105.
Plant-lice as food of Coccinellide, 74.
| Platychirus quadratus, 73.
presumptive enemy of Pea-
| louse, 76.
Platygasteride, 50.
| plorabunda, Chrysopa, 73, 77, 78.
' Plowing clover field soon
hay badly infested
borer, 95.
seeds under to destroy Clover Seed-chal-
cid in hibernation, 60.
under after second season to get rid of
Clover Leaf-weevil, 92.
in spring when Clover Root-borer is very
destructive, 45.
when Pea- or Clover- louse is abun-
dant, 81.
old clover field under in fall or early spring,
then harrowing and rolling, as remedy for
Clover Seed-caterpillar, 65. :
soon after removal of clover hay crop, 95.
Poa annua as food plant of Clover Sitones in
Europe, 113.
| Podabrus rugulosus as enemy of Pea- or Clo-
ver- louse, 73, 79.
_ podisi, Telenomus, 77.
Podisus maculiventris as enemy of Pea- or
Clover- louse, 79.
attacking syrphid larve, 77.
preying upon coccinellid pup, 75.
spinosus, +73; ‘75, 77.
politum, Mesogramma, 73, 76.
Pollen grains and spores as food of Cocci-
| nellida, 74.

parasite of Clover

or Clover-

after removal of
with Clover Root-

Potato-beetle, Colorado, eggs of, eaten by Me-
gilla maculata, 74.
Praon cerasaphis, 73.
pratense, Phleum, 107.
Trifolium, 43.
Pricer, John Lossen, 29, 30.
Proctotrypid parasite of Chrysopa eggs, 78.
of eggs of Podisus maculiventris and
Euschistus variolarius, 75, 77.
Pseudococcus trifolii, 117-120.
in nests of Lasius niger americanus, 27.
(See Clover-root Mealy Bug.)
punctatus, Phytonomus, 83.
Pyralis costalis, 96.
farinalis injurious to stored clover hay, 97.
Pyrethrum and flour, dusting with,
stacking clover hay, 99.

Q

quadratus, Platychirus, 73, 76.
quadrimaculatus, Collops, 90.

R

Ragweed as food plant of Clover Stem-borer,
107.
ramosus, Erigeron, 107.
Red Clover, 41, 42.
as breeding plant of Clover Callipterus,
106.
food plant (in Europe)
Leaf-midge, 99.
of Clover Sitones, 113.
of Sitones hispidulus, 116.
of Sitones lineellus, 117.
average crop of seed of, in northern and
central Illinois, 43.
chief food plant of Clover
pillar, 61.
of Clover Seed-chalcid, 53.
of Clover Seed-midge, 46, 50.
Clover-root Mealy Bug common on, some-
times killing, 118.
damage to, by Pea- or Clover- louse, 66,
67-68.
injured by Clover Stem-borer, 107.
one of chief food plants of Clover Root-
borer, 93.
pollination of, 44.
preference of, by Clover Leaf-weevil, 83.
short rotation period in, as measure against
injurious insects, 46, 65, 95.
Reinecke, Ottomar, 83.
Remedies and preventives for insect depreda-
tions: bisulphid of carbon, 52, 99.
brush and cultivator, or brush and pan,
method, 81.
burning chaff and stems of Clover after
hulling, 60.
clipping off or pasturing off heads of
first-year Clover, 60.
cutting and storing Clover hay early,
65, 82.

when

as of Clover

Seed-cater-

xxl

Remedies, ete.—Continued.
cutting Clover early, 51, 82, 112.
or pasturing Clover in latter part of
its first season, 82.
volunteer Clover in early June and
speedily disposing of heads, 65.
deep, thoro, and repeated stirring of
old corn ground, 24.
destruction of larve, 92.
of outstanding Clover, 60.

of volunteer Clover, 46, 52, 60, 65,
112.
drilling in Clover seed, 61.
dusting hay with pyrethrum and flour

when stacking, 99.
early pasturing or cutting of Clover,
45, 46, 51.
fertilization, high, 81.
fertilizers, 95.
heating seed, 52.
hydrocyanic acid gas, 99.
kerosene emulsion, 81.
logs or rails put under clover haystacks,
98.
maintenance and increase of fertility of
soil, 25.
mowing back Clover, 51.
pasturing Clover in fall of the first year,
65.
lightly ot clipping back in spring,
45, 52, 82, 92.
planting early maturing peas, 81.
peas distant from Clover, 81.
plowing clover seeds under, 60.
under after second season, 92.
infested Clover under, 45, 81, 92.
old clover fields, then harrowing and
rolling, 65.
soon after removal of clover hay crop,
95.
repellents, 1-26. See Corn Root-aphis
repellents and Rex Dip.
Rex Dip, 14, 15, 16, 17, 22, 23.
salting hay at bottom of stack, 98.

seed-corn test when repellents are to
be used, 26.
short rotation period in Clover, 46, 65,
95.
in Corn, 24.
sowing Clover remote from old clover
fields, 65.

whale-oil soap solution, 81.
and tobacco decoction, 81.

repanda, Cicindela, 90.

Repellents against Corn Root-aphis, experi-
ments with, 1-26. See under Corn Root-
aphis.

Rex Dip as a repellent against Corn Root-

aphis and Corn-Field Ant, 14, 15, 16,
We

special test on reaction of Corn-Field
Ant to, 22, 23.

Xxll

Rhyncholophide, 73.

Rhyncholophus parvus as enemy of Pea- or
Clover- louse, 73, 79.

ribesii, Syrphus, 73, 76.

Riley, C. V., 75, ‘84, 86, 88, 89, 90; 92, 95,

97, 99.
Root-aphis, Corn. See Corn Root-aphis.
Root-borer, Clover. See Clover Root-borer.

Root-lice as food of Corn-Field Ant, 37.

Root-louse, Common Grass, on roots of Corn
and weeds, attended by Corn-Field Ant, 38.

Rotation period in Clover, short, as measure

against clover insects, 46,
against Clover Root-borer, 95.
against Clover Seed-caterpillar, 65.
in Corn, short, as measure against Corn
Root-aphis, 24.
Rudbeckia laciniata as food plant of Clover
Stem-borer, 107.
rufilabris, Chrysopa, 73, 78.
rugulosus, Podabrus, 73, 79.

Ss

Salt, effect of, on germination of seed-corn
tested, 10.
Sanderson, E. D., 50, 66, 68, 69, 76, 79, 80, 81.
sanguinea, Coccinella, 73, 74.
sativa, Medicago, 83.
scabrinodis lobicornis, Myrmica, 122.
Scale insects, insect enemy of, 74.
Scalecide, effect of, on germination of seed-
corn tested, 11.
schaufussi, Formica, 34.
Schizoneura panicola, 39.
on roots of Corn and weeds, attended by |
Corn-Field Ant, 38.
Schwarz, E. A., 116,
Scolytide, 92.
Seed-caterpillar, Clover.

See under Clover.
Shepherd’s-purse as food plant of Pea-
Clover- louse, 67.
Sigalphus tibialis, 65.
Sitones, Clover, 112-117.
flavescens, 112-117. See Clover Sitones.
generic characters of, 114.
hispidulus found feeding on Red Clover,
116. |
lineellus injurious to Clover and Alfalfa in
Europe, 116, 117.
larva similar to that of S. flavescens, 117.
tibialis, 116.
Smith, J. 2, -S0e
Snider, E. Q@., 70; 71,
Soldier-beetle as enemy of Pea-
louse, 79

or

See Clover Sitones.

or Clover-

Solenopsis molesta-in hill of Corn, 38. (See
Errata.)
domesticated in nests of Corn-Field Ant,
34.

Soy-beans apparently immune from attack by
Pea- or Clover- louse, 67.

Spherophoria cylindrica as enemy of Pea- or
Clover- louse, 73, 76.
spherosperma, Empusa, 73, 91.
Entomophthora, 91.
spinosus, Podisus, 73, 75, 77.
squamosa, Geoica, 39.
Stem-borer, Clover. See Clover Stem-borer.
Sugar-beet, Clover-root Mealy Bug_ reported
from, 118.
Sulphur, effect of, on germination of seed-corn
tested, 10.
special test on reaction of Corn-Field Ant
to; 225 23:
Sweat bees in
phide.
Sweet Clover, Wild, as food plant of Clover
Stem-borer, 107.
Pea as food plant of Pea- or Clover- louse,
67.

clover fields, 75. See Syr-

.syrphi, Pachyneuron, 73, 76, 80.

Syrphid larve, enemies of, 77.
Syrphide, appearance and habits of, 75.
as enemies of Pea- or Clover-louse, 73, 75-
be
enemies of, 80.
Syrphus americanus, adult and larva of, char-
acterized, 76.
as enemy of Pea- or Clover- louse, 73, 76.
ribesii as enemy of Pea- or Clover-louse,
VRE PASE
parasite of, 76.

T

Tar-, or coal-tar,- water, effect of, on germi-
nation of seed-corn tested, 5, 6, 11.
Telenomus podisi as parasite of eggs of pen-
tatomids, 77.
Telephorid larva as enemy of Clover Root-
borer, 95.
Telephorus bilineatus, 95.
Tetrastichus bruchophagi, 58.
probably a parasite of Clover Seed-chal-
cid, 59-60.
carinatus as parasite of
Seed-midge, 50.
spp. as parasites of larva and pupa of Clo-
ver Seed-midge, 50.
Thaxter, Roland, 73, 91.
Thistle as food plant of Clover Stem-borer,
107.
tibialis, Phanerotoma,
Sigalphus, 65.
Sitones, 116.
Timothy as food plant of Clover Leaf-weevil,
83.
of Clover Seed-weevil, 42.
of Clover Stem-borer, 107.
hay and Clover Hay-worm, 96.
PTitws; eS Gt oes
Tobacco-water, effect of,
seed-corn tested, 11.

larva of Clover

65.

on germination of

XX1il

Torymus as parasite of larva of Clover Seed-
midge, 50.
tredecimpunctata, Hippodamia, 73, 74.
Tree-cricket as enemy of Pea- or Clover- louse,
78.
trifida, Ambrosia, 107.
trifolii, Callipterus, 103.
Cecidomyia, 99.
Coccus, 117.
Dactylopius, 117.
Dasyneura, 99.
Hylastes, 92.
Hylesinus, 92.
Pseudococcus, 27, 117.
Trifolium pratense. 43. See Red Clover.
Trioxys cerasaphis, 73.
as parasite of Pea- or Clover- louse, 80.
Triphleps insidiosus as enemy of Pea- or Clo-
ver- louse, 79.
of Clover Seed-midge, 51.
Turkeys as enemies of Clover Leaf-weevil, 90.
Turpentine, effect of, on germination of seed-
corn tested, 5, 6.

U

Urtica dioica and U. gracilis as food plants
of Clover Stem-borer, 107.

U. S. Department of Agriculture,
Entomology of, 41.

Bureau of

Vv

variolarius, Euschistus, 73, 75, 77, 79, 80.
vernoniz, Bracon, 65.
Vetches, 42.
or tares, as food plant of Pea- or
louse, 67.

Clover-

vulgaris, Isocratus, 73, 76, 80.

Ww
washingtonensis, Aphidius, 73, 80.
Webster, F. M., 50, 52, 60, 62, 83, 90, 94,
95; 96; 97, -98)-995 106, 113, °114, 115.
Webster, R. L., 41, 59, 70, 71, 90, 105.
Weed, C. M., 106, 111.
andwhart. Gs Act 75.
Weeds as food plants of Clover Stem-borer,
107.
West, J. A., 94.
Whale-oil soap and tobacco decoction to con-
trol Pea- or Clover- louse in gardens, 81.
solution to control same, 81.

| Wheéler, Wm. Morton, 27.

White Clover, 41, 53.
as food plant of Clover Leaf-midge, 99,
100.
Clover-root Mealy Bug common on, some-
times destroying, 118.
injured by Clover Seed-caterpillar, 61.
by Clover Seed-midge, 46.
injury to, by Clover Sitones, 113.
preference of, by Clover Leaf-weevil, 83.
White-grubs as food of Corn-Field Ant, 37.
number of, per acre, exposed in plowing old
corn field, 14.
Wild Lettuce as food plant of Clover Stem-

borer, 107.
Sweet Clover as food plant of same, 107.
x
Xambeu, Vincent, 114.
Wi
Yarrow as food plant of Clover Stem-borer,

107.

TWENTY-SIXTH REPORT

OF THE ey pf |
MA ee
22\64

Ay
NA }

STATE ENTOMOLOGIST!"}

ON THE

Noxious and Beneficial Insects
OF: AEE;

SLATE OF IL LENOIS

FIFTEENTH REPORT OF STEPHEN A. FORBES

1914

oO

\

AS

+;
Ce

ror

TWENAY-sIXTH REPORT

OF THE

STATE ENTOMOLOGIST

ON THE

Noxious and Beneficial Insects

OF THE

SEALE OF JELINOTS

PIRTEENTH REPORT OF STEPHEN A.. FORBES

1911

CONTENTS

PAGE
Some Important Insects of Illinois Shade Trees and Shrubs................ 1
The Catalpa Sphinx, Ceratomia catalpe Bdv. .........0. ccc ccc eee cee 2
ithe Hall Web-worm, Hyphaniria teator, Harris.................0...00.< 4
The Yellow Poplar-Caterpillar, Apatela populi Riley..................4. 6
The Walnut Caterpillar, Datana integerrima G. & R. ...............005. 8
The White-marked Tussock-moth, Hemerocampa leucostigma S. & A. ..... 10
The Brown-tail and Gypsy Moths, Huproctis chrysorrhea Linn. and Por-
REIS CRIS NEP VL AWS. 9 cy Gach AE CONROE CeO IOP CRIGE OCC REDD CeE RIE en a ek 14
The Forest Tent Caterpillar, Malacosoma disstria Hbn. ................. 21
The Common Canker-worm or Spring Canker-worm, Paleacrita vernata
ISO Se Bie Bet ed ee OOS SUL CIA IoNo SSBY CRAIC ER CIOS OC aCe oe 23
ihemavacebonen, ocosesia syriigc Harnis. . ssc sees cee eee ac te 2h
Two Poplar Borers, Memythrus tricinctus Harris and M. dollii Neum. .... 31
AMV ULM DONeTAn SeSid. PIGlINCs! GamGunie ere eaters). siaieccneeinv sie wcletae eae veo. 34
Piawviamie uBOrer, /Seste <AceMns Clem ss 2 S215 6 sete chet Oe duals wk wld asa we 35
bes Nimebark boner; Nesta<scitiid, Hants: ae ccs oe te visas hea see 37
The Bag-worm, Thyridopteryx ephemereformis Harris................... 38
The Poplar and Willow Borer, Cryptorhynchus lapathi Linn. ............ 40
The Dogwood Twig-girdler, Oberea tripunctata Swederus................. 44
iBhemEGcust BOLeL-Gyllenes TOOL, HOLSbe «te .ic ts cise a cle sek Ge esc cuetel las 2s 48
The Oak Twig-pruner, Hlaphidion villosum Fabr. *................2........ 50
the Bronze Birch-borer, Agrilus anaiis Gory....-.0-....---5-.0.065-.-- 53
ihe Scurty Scale-Chionaspis furfura Witch. 22.2 es ew ks coke ewe ee ees 55
The Oyster-shell Scale, Lepidosaphes ulmi Linn. 2.2.2.0... 0... eee 57
The San Jose Scale, Aspidiotus perniciosus Comst. ..................+.- 58
Putnam’s Seale, Aspidiotus ancylus. Putmam...............-...-.2-0+00% 61
The Walnut or Willow Scale, Aspidiotus juglans-regie Comst. .......... 61
The Cottony Maple Scale, Pulvinaria vitis Linn. .............. 2.2200 eee 62
Miscellaneous wEICONOMMle BINSECUS: 22 .ct.1c ss. eek Melee a eeiae ease nee e Hie nes 68
ithe Heartwood. Borer, Laranara orunnea Wabre o9......-..-....+..-5e<e 68
AULOMLAULROULOLOLO | nyilleammtal bust pth tt aekeya choclate takaiceN ite clic ioe oer gh yee died enecenel ous 73
The Green Fruit-worms, Teniocampa and Xylina..............+...+...- 75
TEER OG DOOD GH” CHG “hres ots eae Oey Die ted oo Geneon eT ee 78
NCL MO MCNULEIIN OL CMV ch lwo meee tareecl satis a miees ers or sok als Sashes ao gcse ecaiwtaierae 80
Tabulation of known differences between species.............-......0- 82
ihe Apple-Mlea-weevil, Orchestes-canws Horn: ... 2.5.5 ee ek ene cw aes 83
The Strawberry Leaf-roller, Ancylis comptana Frol...................... 86
The Strawberry Crown-girdler, Otiorhynchus ovatus Linn. ............... 90
The Blackberry Leaf-roller, Exartema permundanum Clem. .............. 94
Black Gnats im Cucumber Houses, Scitara sp. ....0 00.222 ccc cee cttw ees 95
On the More Important Insects of the Truck-farm and Vegetable Garden.... 99
General Farm Methods for the Control of Insects....... 0004... 2.02 0.005. 100
ALES OO RUGT DCTS sede CRC EOE RRR CERI PAC CEO ee 102
The Common Asparagus-beetle, Crioceris asparagi Linn. .............. 103
COD NERO CHUL (OITUL TOUR ee eae 9 Doce Oboe aan Co. en oh Molen oie Coe ae ORO 104
The Imported Cabbage-worm, Pontia rape Linn. ..................... 104
The Variegated Cutworm, Peridroma margaritosa Haw. ............... 107
The Cabbage Root-maggot, Phorbia brassice Bouché..... ............. 108
The Cabbage Plant-louse, Aphis brassice Linn. ......5......2265.-005: 111

The Cabbage Flea-beetle, Phyllotreta vittatata Fabr. .................. 113

PAGE
Cuewmber and Melon os. te. ce roe ie HRs = ot gee See oes 114
The Striped Cucumber-beetle, Diabrotica vittata Fabr. ................ 115
The Squash-bug..Anasa (ristis DeGeerr ac... gene, ieee 118
The Melon Aphis; Aphis gossypu, Glover. 2-415. 2 te ee 120
The Greenhouse White-fly, Aleyrodes vaporariorum Westwood.......... 121
The Onion, Thrips, -Lhrips- tabvacs Winds. > ee sire eee eee 123
The Red Spider, Tetranychus bimaculatus Harvey..................... 124
The Eel-worm, Heterodera radicicola Greeff..............220220cceeces 126
TOUGUCE ys 02 ai tatista yay eho pore ge tye a me real ie aon fie, Ach opal let tsa, CRA OR ee TE 129
The Variegated Cutworm, Peridroma margaritosa Haw. ............... 129
The Lettuce Plant-louse, Macrosiphuwm lactuce Kalt. .................. 132
The Imported Cabbage-worm, Pontia rap@ Linn. ...................-.: 133
LEE a Te LER REL ae eee CE aA Ce ne SEN ad ets Fel toy Ein sips) BONS 133
The Onion-maggot, Phorbia ceparum Meigen...................:....-+ 133
The Onion Lhrips, “fhrpsitabact, Wind-stce aa eee eee 137
Gorden - POds) vers tre he thoks are ole ee eee Nee) SeepE ae RE Na Meo oR oe tose a 138
The ‘Pea-louse, Macrosiphum. “pisy Walt). hak. acme oe teens ene ee 138
POLHEO. CS 2 Siatece ese ayaa sino odete lS faleborcakal elles Fave Wok teal aft a: ence earch Rene Poot eee eee 140
The Colorado Potato-beetle, Leptinotarsa 10-lineata Say.... .......... 14]
Wire worms: “Doanoniws, CONfFUSUS, LOC. Sere 2 2 on. Aebe icine aoe en eee 143
The Potato Flea-beetle, Hpitriw cucwmeris Harr. ................-..+:- 145
The Potato Plant-louse, Macrosiphum solanifolii Ashm................ 145
DUOC ocx ta oe Siac ee oho 5 AOE aR eR OE oe Ra At al awe ice ates ee Ieee 146
The Omnivorous Plant-house, Myzeus persice Sulz. .................... 146
POMLON ce oRiata «a apejentisltnele 'scuagensto tops loie: @lave nee Loos (cies tt eee eet 146
The Stalk-borer, Papaipema nitela Guen. .. 25.00.60... ee ae tee ce eeses 147
Preparation of Insecticides fer Use against Insects Injurious to Garden
and “Hothouse Vegetables. ian. aaa So se eee 148-160

Classification and. SynoptiealList.c 2. <2 vids a oe oe eee oe 149

SOME IMPORTANT INSECTS OF ILLINOIS
SHADE TREES AND SHRUBS

By STEPHEN A. FORBES, STATE ENTOMOLOGIST

The protection of the shade trees and ornamental shrubs of
Illinois against insects has been for several years a problem of rap-
idly increasing importance. Many of our most desirable trees
and shrubs are liable to slow destruction by obscure insect
pests understood little if at all by those immediately con-
cerned. Trees which have grown for years, becoming more at-
tractive, more valuable, and more highly valued year by year, begin
to weaken and decay, the owner does not know why. ‘This is often
due to borers or to scale insects, the presence of which has not been
detected or suspected, but whose injuries might have been prevented
if the facts had been known in time. More sudden losses are fre-
quently caused by overwhelming attacks of leaf-eating insects
which, altho conspicuous, are not dealt with because proper measures
of procedure are not known. Observations and experiments upon
this subject have been for several years a prominent part of the work
of the office. Beginning in 1898, repeated careful examinations
have been made of the trees and shrubs of the parks and boule-
vards of Chicago, and this work has been extended from time to
time to other cities and towns thruout the state. Wiauth the estab-
lishment of a field assistant in Chicago in 1907, the subject received
more continuous attention at the hands, first, of Mr. H. FE. Hodg-
kiss and, later, of Mr. John J. Davis, the latter of whom espe-
cially has made many studies of the life histories of species previ-
ously but litthke known, and has added a mass of details to our
knowledge of the subject in all its parts.

The general subject is still under investigation, and will be in
due time reported upon in a much fuller and more elaborate article,
but the present brief preliminary paper has been prepared in the
hope that it may be found of immediate practical use to municipal
authorities in control of parks, boulevards, and streets, to town im-
provement societies, and to owners. of lawns and other private
premises the appearance of which they are striving to improve by
the use of trees and shrubs.

2

THE CATALPA SPHINX
(Ceratomia catalpe Bdv.)

One of the most destructive of the few insects to which the
catalpa tree is subject is a large showy caterpillar known as the
catalpa sphinx (Fig. 1). It is a southern insect, and has not been
found in this state north of Clay and Richland counties, altho it has

Fig. 1. Catalpa Sphinx (Ceratimia catalpe): a,egg mass; 6,newly hatched
larve; c d. lary@# one-third grown and one joint showing its dorsal pattern;
é, /.g,h,t, mature larve. variously marked, and single joints showing dorsal
patterns: j, pupa: *. moth; J. ege, enlarged; others all slightly less than
natural size. (Ohio Experiment Station )

3

extended up the Atlantic coast as far as New Jersey. It is likely
to appear suddenly in large numbers upon single trees, stripping
them completely.

The full-grown caterpillar (Fig. 1, e, f, h) is rather strongly
marked, mie a broad velvety black stripe on the back and sulphur-
yellow sides spotted with black, while the under side of the body is
pale green. It is unusually variable in color, however, there being
both Tight and dark forms. It is from two and a fourth to three
inches long, and has a hornlike appendage projecting from the
hinder end of the back. The young caterpillars (Fig. 1, c) are
pale yellow and spotted with black. There are probably but two
generations in Illinois. The caterpillars leave the trees and go
into the ground to pupate (Fig. 2).

Fig. 2. Catalpa Sphinx, Ceratomia
catalpe, pupain cellin earth.

The parent insect is a large heavy-bodied moth (Fig. 1, k) with
strong, narrow, brownish-gray wings, with obscure lines and spots
of black. The eggs (Fig. 1, a) are laid in masses on the leaves,
sometimes as many as a thousand in a bunch, and the young, on
hatching, feed at first in companies—a fact which makes it easy to
destroy them if their presence is detected early, by picking off or
spraying the infested leaves. A general spraying of a tree with
arsenate of lead or Paris green will destroy the caterpillars at any
time. Professor H. Garman, of Kentucky, says that the nearly
grown worms can be shaken or jarred down from most catalpa
trees and readily destroyed by hand.

4

THE Fatt WEB-worM
(Hyphantria textor Harris)

The fall web-worm is the only common Illinois insect which
makes a large conspicuous. web in late summer and in fall, inclos-
ing a considerable number of the leaves and twigs of a branch, together

Fig. 3. Fall Web-worms, Hyphantria tertor. and their web, on apple-tree.
(New Hampshire Experiment Station )

D

with a colony of caterpillars which feed under its protection (Fig.
3). It is unfortunately often called in Illinois the tent caterpillar,
but the latter name is properly applied only to a caterpillar, not
often seen in this state, which makes a small compact web in the
forks of a branch in spring, which it uses only for protection while
not eating.

The web-worm is an almost universal feeder and has been
found on about a hundred and twenty species of fruit, shade, and
ornamental trees, upon the leaves of which it feeds. It is one of
.the most annoying pests of the tree grower, its numerous large
webs, enclosing brown, skeletonized leaves, making the tree very
unsightly, and the injury done, as it spreads from branch to branch,
often being considerable. While the caterpillars are growing they
do not wander from their common web, but enlarge this to cover
fresh leaves as fast as those within it are devoured. When they
have nearly completed their growth, however, they scatter far and
wide, running briskly about when disturbed, and feeding on almost

Wh i
i
4
3
i}
|
t
7

Fig. 4. Fall Web-worm, Ayphaniria textor: a, b,
larve, light and dark varieties; c, pupa; d, moth, *
spotted variety. Allslightly enlarged. (New Hamp-
shire Experiment Station.)

6

every green thing they find. At this time they become, when very
abundant, an extremely destructive and annoying pest.

They are about an inch long when full grown, varying from pale
yellow or grayish to a dark bluish-black hue. (Fig. 4, a, b.) The
body is covered with long straight hairs grouped in tufts rising
from small black or orange-yellow tubercles, of which there are a
number on each segnient. When mature, the caterpillars go to the
ground, into which they burrow a short distance, or they creep
under shelter above ground, where they form slight cocoons of
silken web interwoven with the hairs from their bodies. Within -
these they change to dark brown pupe (Fig. 4,c), and in this con-
dition they pass the winter. The moths emerge in spring and
lay their eggs in broad patches of several hundred each, on
the under side of the leaves near the end of a branch, late in
May and early in June. The adult insect is usually pure white,
but is sometimes white spotted with black. There are either one
or two broods of this species, according to the latitude, two in
southern and central Illinois and probably but one in the northern
part of the state.

The simplest and most effective method of controlling these
insects is to destroy their webs, and the caterpillars within them,
either by cutting off the twigs which bear them and crushing or
burning them immediately, or by burning the webs on the tree.
A bundle of rags or a few corn-cobs, or even a porous brick, wired
to the end of a pole long enough to reach the nest and saturated
with kerosene, makes a good torch for the purpose. Care must
be taken, however, not to injure the tree, and to destroy the scat-
tering worms which may drop from the nest without being killed.
Where the infestation is too general to make this method con-
venient, or where the webs are so high in the trees that they can
not be readily reached, a spray of arsenate of lead will eventually
kill the web-worms as they extend their webs over the poisoned
foliage. Paris green may be used instead, but the lead arsenate
is to be preferred because, being much more adhesive, it lasts longer
on the tree. This method is most effective when the caterpillars
are young, since they are then extending their webs rapidly and are
likely to be more promptly poisoned than when they are virtually
full grown.

Tur YELLOW Poplar — CATERPILLAR
(Apatela populi Riley)

The prominence of the Carolina poplar as a city tree, especially
in situations where it is difficult to find any other which can en-
dure the conditions prevailing, makes it the duty of the Entomolo-
gist to discuss the insect enemies of even this rather inferior va-

riety.

rf

Among those which have recently been found most injurious
to the poplar is a large and rather handsome, light yellow or pale
green, very hairy caterpillar (Fig. 5), most easily known by five
long pencil-like tufts of black hairs rising one behind the other on
the middle line of the back, the first on the fourth segment of the
body and the fifth on the last. This caterpillar was particularly in-
jurious to poplars and considerably so to willows in Chicago in
1909. It has been noticed by us also in Peoria, Danville, and East
St. Louis. It feeds on the leaves in midsummer and again in fall,
there being two generations in a year. It sometimes completely

Fig.5. The Yellow Poplar-Caterpillar, Apatela popuii,
natural size.

strips a tree, rendering it unsightly and putting it in poor condition
to withstand unfavorable conditions or to resist the attacks of
more destructive insects.

The caterpillar when full grown is about an inch and a half long,
the skin yellowish-green, and the long, soft, drooping hairs yellow.
The pencil-like tufts referred to rise from the fourth, sixth, sev-
enth, and eleventh segments, those on the seventh and eighth being
the smallest. The head is shining black and there are black spots
on the top of segments one and two. The young are almost white,
and the black tufts of hairs are shorter, but still conspicuous. The
caterpillar is of a sluggish habit, and when at rest it commonly lies
curled up, with the ends of the body together. When full grown
it spins a loose, pale yellow cocoon of silk interwoven with its
own hairs. This is generally placed in a crevice of the bark, under
the edge of a fence board, or in some similar sheltered place. The
winter is passed in this chrysalis stage, from which a large, pale
gray moth emerges the following May.

The caterpillars are most easily destroyed when young, for they
do not at first scatter from the branch upon which they were born.

8

Later they can readily be collected singly by hand from trees of
small size, or they may be poisoned, like most of the leaf feeders,
by spraying with arsenicals when they are active on the tree.

THE WALNUT CATERPILLAR
(Datana integerrima G. & R.)

The most annoying insect enemy of the walnut is a blackish,
somewhat striped, hairy caterpillar (Fig. 6), an inch and a half
long when jull grown, which eats the leaves during the latter part
of the summer, often largely denuding the tree. It makes itself
particularly offensive on lawns by dropping quantities of refuse
from the tree and by crawling over walks and buildings when it
comes down to go into the eround.

This caterpillar is readily distinguished by its loose coat of
soft whitish hairs, and particularly by its habit of raising both ends
of the body when at rest and throwing itself into this position and
jerking sidewise when disturbed. It often attracts attention by col-
lecting in masses upon the larger branches or the trunk of the tree
preliminary to molting, piling up in this way two or three layers
deep. When full grown it comes down the trunk to the ground,
wanders about to a short distance and enters the earth an inch or
two, changing there to a reddish-brown or blackish-brown chrysalis
(Fig. 6, B). In this stage it winters, emerging the following sum-
mer, mainly in June and July, in the form of a buff-brown moth
(Fig. 6, A) with darker bands across the fore wings. The females
lay their eggs in clusters varying from seventy-five to a hundred,
according to some observers, and from five hundred to twelve
hundred, according to others, and the young hatching from these
feed in dense clusters, completely devouring every leaf as they go.
When all the leaves on one twig or branch are destroyed, they mi-
grate to another, sometimes in a distant part of the tree. They
ose their gregarious habit as they mature, and by the time they are
full grown they scatter here and there over the greater part of
the tree. There is but a single generation in a year.

Altho they are most frequently seen on the walnut, they are
common on butternuts and hickories, and are a pest to the grower
of the pecan. They have likewise been found on beech, oak, willow,
honey-locust, apple, and thorn. Trees in the forest are not likely
to suffer, but those on streets and lawns are sometimes so completely
stripped by September that they stand almost as naked as in mid-
winter, only the green nuts remaining on the branches.

This account of their habits is sufficient to suggest various avail-
able methods of destroying them. On trees small enough to be
reached they can be readily killed while young by clipping off the

9

infested twigs on which the caterpillars are grouped in colonies.
They are particularly exposed to attack as they assemble in masses
for their later molts, when a light spray of kerosene will readily
kill them. They are also susceptible to arsenical poisons sprayed

Fig.6. Walnut Caterpillar, Datana integerrima:
(Kentucky Experiment Station.)

A, moth; B, pupxe. Natural size.

10

upon the leaves, but these must be used in unusual strength. We
have found three pounds of arsenate of lead to fifty gallons of wa-
ter sufficient to kill the full-grown caterpillars. On one occasion
a tree nearly fifty feet high was effectively sprayed by the aid of a
twenty-eight-foot ladder and a twelve-foot extension rod with a
nozzle on the end, about twenty-five gallons of the spray being nec-
essary for a thoro treatment. If these various measures have
been neglected and the caterpillars have left the tree, they may still
be disposed of in the pupa stage by digging up and working over
the ground under the branches and for a little distance outside, to
a depth of three or four inches.

THe WHITE-MARKED TUSSOCK-MOTH
(Heimerocampa leucostigma S. & A.)

The most destructive leaf-eater infesting shade trees in the
larger cities of Illinois and especially in Chicago is the caterpillar of
the white-marked tussock-moth. It often completely defoliates large
trees, those most seriously injured being the elm, the soft maple,
the linden, the birch, and the horse-chestnut. (Fig.7.) Almost
every kind of tree, excepting conifers, is subject to its attack, and
it sometimes becomes decidedly injurious in orchards. In Chi-
cago it has been noted as injurious to apple, box-elder, hard maple,
Norway maple, poplar, willow, oak, ash, locust, hickory, catalpa,
and sycamore, and to several shrubs, including dogwood, button-
bush, Viburnum, and bladdernut (Ptelea). In September and
October, Ig10, it was found in every one of eighteen towns visited
by Mr. John J. Davis, present in small numbers in seven of them,
common in nine, and in destructive numbers in two.

This is a well-marked insect, very easily recognized, especially
the caterpillar and the egg mass—the two conditions against which
measures of destruction must be taken. The hairy caterpillar (Fig.
8), bright yellow in general color and striped with black, and about
an inch and a half long when full grown, is a really beautiful object.
It may be known by its coral-red head, by two plumelike tufts of
long black hairs projecting upward and forward from the back near
the head, by a single similar tuft at the hind end of the body, and
especially by four thick, short, brushlike clusters of cream-colored
hairs arranged, one behind the other, in front of the center of the
back. In this condition it may be found upon infested trees in
June, July, and August.

There are two generations of the caterpillar in a year in north-
ern Illinois, possibly three farther south. The egg masses (Fig. 9)
from which the caterpillars hatch may be found in fall, winter, and
early spring. They form, when first deposited, frothy, oval, snowy

=

11

Fig.?. Linden tree in a park in Chicago, defoliated by larve
of White-marked Tussock-moth (Hemerocampa leucostigma). The
few leaves on the tree have all appeared since the defoliation.

white patches about an inch in length, on the tree trunks, in the
crotches of the larger branches, or in other more or less sheltered
places, such as the edges of weather-boards and the under sides of
the eaves of porches. Conspicuous objects at first, their color, under
exposure to the sooty air of Illinois towns, is soon deadened to a
dirty gray. The caterpillar begins to hatch from the over-wintering
egg masses about the middle of June in Chicago (June 18 in 1909)
and gets its growth in about a month. Feeding at first on the under
side of the leaf, which it skeletonizes by eating off the soft tissue,
it later eats inward from the edge of the leaf, devouring everything
except the principal veins.

12

The young caterpillars drop down, hanging by silken threads,
when the tree is jarred, and sometimes spin down without being dis-
turbed, when they may be blown to a considerable distance by the

Fig. 8 White-marked Tussock-moth, Hemerocampa
leucostigma, larva. Natural size.

wind. When nearly full grown, they are great travelers, going
from tree to tree and even moving in large numbers from a de-
foliated tree to others near by. When full grown, the caterpillar

Fig. 9.

White-marked Tussock-moth. /Hemerocimpa leucostiyma, COCOOLS
and egg masses on tree trunk in a park in Chicago.

13

spins, on the tree, a delicate grayish cocoon of silken web mixed with
its own long hairs. It changes to a pupa within a few hours after
the cocoon is finished and continues in this condition from ten days
to two weeks.

The adults are moths, the females (Fig. 10) of which differ
very widely from the males (Fig. 11) in the fact that they are
almost absolutely wingless. The males have good wings and at

Fig. 11. White-marked
Tussock-moth, /emero-
campa leucostigma, male.
Natural size.

Fig. 10. White-marked Tussock-
moth, Hemerocampa leucost-gma,
female and egg masses. Natural
Size. (Connecticut Experiment
Station )

least the average power of flight. They are of an ashy gray color,
with dark wavy bands across the fore wings, a small black
spot on the outer edge near the tip, a blackish stripe be-
yond this, and a minute white crescent near the hind angle.
The wings, when expanded, measure about one and a fourth
inches across. ‘The female has little of the appearance of a
moth, her wings being reduced to the merest rudiments. Her
thick, oblong-oval body is of a light gray color, with rather
long legs, and is distended with eggs. When she comes out
she lays her egg mass on the cocoon from which she emerged—a fact
which makes it plain that the species can spread only by way of the
wandering caterpillars, or by the transportation of egg masses on
young trees. The eggs of the last generation are ordinarily pro-
duced in September and the winter is passed in this condition.
Many insect parasites infest the pupa and do much towards hold-
ing the species in check. They are not usually abundant enough,
however, to control it completely. In the fall of 1907, for example.
one of my assistants reported that 75 percent of the cocoons of
the tussock-moth in the Chicago parks were parasitized, but the
caterpillars were nevertheless very numerous and destructive the

14

following year. Birds eat them, but not freely enough in the larger
cities to reduce their numbers materialiy.

Three measures of destruction are applicable to this pest and
sufficient for its control. These are the destruction of the egg
masses in winter, banding trunks of uninfested trees in spring, and
spraying infested trees in summer. The trunks and larger branches
of trees, as well as all objects surrounding those infested the season
before, should be carefully examined in winter and spring for egg
masses, and all these within reach should be scraped or cut away
and burned or otherwise destroyed. Those beyond convenient reach
may be killed in place by touching each egg mass with a sponge or
brush attached to the end of a long pole and dipped in crude creosote.

As the insect spreads from tree to tree only in the caterpillar
stage, an uninfested tree may usually be protected completely by
banding the trunk in such a way that the caterpillars from adjacent
trees can not climb beyond the band. Sometimes, however, the
branches of trees intermingle or touch in such a way that the cater-
pillars may go from one tree to the other without coming down
to the ground. These bands should be applied to the tree soon
after the caterpillars begin to appear in spring, and they should
be renewed from time to time as they are made useless by exposure
to the weather.

Either one of two kinds of bands may be used. The trunk
may be surrounded, at a convenient height, by a belt nine inches
wide of what is known as tree tanglefoot, applied with a brush;
or bands of cotton batting about four inches wide may be tied
closely about the tree by a string passed around the middle of the
band, the upper half of which should then be turned down over it.

Where the preceding measures have been neglected and trees
are being defoliated, the injury may be stopped by spraying with
Paris green or arsenate of lead. This, however, is a difficult and
somewhat expensive operation with large trees, and may be ren-
dered unnecessary by destroying the egg masses and banding the
trees as above described.

Tur BROWN-TAIL AND Gypsy Morus
(Euproctis chrysorrhea Linn, and Porthetria dispar Linn.)

These two frightful insect pests, altho present in America,
the first for about forty years and the second for nearly half as
long, have neither of them become established in Illinois, or indeed
made any permanent appearance outside of New England. It will
probably be long before the gypsy moth becomes an inhabitant of
this state, its powers of migration being limited to the larva. The
female, altho well provided with wings, has a very heavy body,
and does not fly. The brown-tail moth, on the other hand, is a

15

strong, swift flier, and is virtually certain to occupy the whole
country in due time, and it is further particularly likely to be in-
troduced into the state direct from its European habitat on nursery
stock imported from France. It winters in the caterpillar stage
partly grown, hundreds of young collecting in single colonies on the
trees, where they hibernate in closely webbed nests (Fig. 12). Hun-
dreds of these nests containing living young were sent, in I1go09, in-

Fig. 12. Brown-tail Moth, Huproctis chrysorrhea, winter nests. Natural
size. (Connecticut Experiment Station.)

to Illinois from France, and only the most active and fortunate in-
spection work prevented their escape in this state that winter. Worse
than this, however, infested cases of nursery stock originating in
France were reshipped into Illinois from other states where the
force of inspectors was not sufficient to deal with the shipments
arriving, and danger from these sources will continue year after
year unless other states strengthen their inspection systems. Fur-
thermore, since stock received in Iowa was shipped to this state
that winter bearing living brown-tail caterpillars, it is extremely
likely that the part retained in Iowa was similarly infested and
that the brown-tail has thus obtained a lodgment there and possibly
in other states adjacent to Illinois. If this is the case it will pres-
ently spread to our state also, especially as the moth flies long dis-
tances before the prevailing winds. It is important, for these rea-

16

sons, that our people should be fully informed and carefully in-
structed in advance in order that the first of these insects to appear
may be detected and destroyed without delay.

The brown-tail moth is a caterpillar (Fig. 13) in the destruc-
tive stage, and, of course, goes thru the four stages of egg, larva,
pupa, and adult. It is easily distinguished in the last of these stages

Fig. 14. Brown-tail Moth, Hu-
proctis chrysorrhea. Slightly en-
larged. (Massachusetts Ex peri-
ment Station.)

ZI.

Fig. 13. Brown-tail
Moth, LZuproctis chrys-
orrhea, larva. Natural
Size. (Massachusetts
Experiment Station.)

from any American insect by the character to which it owes its
name of “‘brown-tail,’” namely, a thick brushlike tuft of orange-
brown hairs at the tip of the abdomen, especially in the female
(Fig. 14). Otherwise both sexes are pure white thruout, except
that occasionally there may be a few black spots on the fore wing of
the male. ‘They measure about an inch and a quarter from tip to
tip of the expanded wings. Any pure white moth of approximate-
ly this size with an orange-brown tuft of hairs at the tip of the
abdomen may be at once set down as the brown-tail; and any one
seeing it in Illinois will render a notable public service by reporting
the fact promptly to the State Entomologist, at Urbana, III.

The winter nests of these caterpillars are also easily identi-
hed, since no native Illinois species hibernates on either tree or
shrub in colonies of living caterpillars inclosed in a web. Any
such cluster of young caterpillars so protected by a common web
may consequently be set down at once as the brown-tail and should,
of course, be promptly destroyed and the facts reported to the
Entomologist. Nurserymen importing European seedling stock can

Li,

not guard too carefully against the accidental importation of this
‘insect pest, as it is widespread in Europe, breeding abundantly on
hedges, trees, and various shrubs, and making its way into the
nursery from infested surroundings.

The brown-tail feeds upon practically all deciduous trees and
many shrubs and even upon herbs. Thousands of fruit trees in
the vicinity of Boston have been killed by it, and damage to maples
and elms in wooded regions has caused the forest to appear brown
in June, an injury which, if repeated for three or four years, has
killed many trees. As the caterpillars pass the winter about a quar-
ter grown, they begin to devour the leaves of trees as soon as these
put out in spring, and even eat the buds and blossoms before the
leaves have spread. Old trees may thus lose all their buds, or, if
not, the foliage itself may be devoured at a later date.

The caterpillar reaches its full size in New England during the
last half of June, and the moths emerging, fly about and lay their
eggs some twenty days later. The small round eggs are laid in
brownish masses (Fig. 15) on the under side of leaves, each mass

Fig5..Brown-tail moth, Huproctis chrys-
orrhew, €gg masses on leaves. | Natural size.
(Connecticut Experiment Station.)

two-thirds of an inch long by a fourth of an inch wide, and con-
taining about three hundred eggs. The full-grown caterpillar is
about two inches long, reddish-brown, with an_ interrupted
white stripe on each side and two red dots on the back near
the hind end. It is also blotched with orange and is cov-
ered with tubercles bearing long barbed hairs, those on the
back and sides with short brown hairs additional, which give
them, when magnified, a velvetlike look. The young hiber-
nating larve are blackish, with reddish-black hairs and black
heads. The pupa is formed among the leaves on the infested tree
or shrub, most frequently at the tips of the branches, where sev-
eral caterpillars may spin a loose web together, each forming, how-

18

ever, its own cocoon within the web. When the insect becomes
abundant, cocoons may be found under fences and at the edge
of clapboards on houses, and in many similar places.

One of the most disturbing peculiarities of a brown-tail in-
festation is the fact that the long barbed hairs already mentioned
are covered with a poisonous excretion, and that they readily pierce
the skin, causing an irritating rash which occasionally results in
serious illness. ‘Indeed,’ says Dr. Howard, “it is not necessary
for the caterpillar itself to come in contact with the skin; at cer-
tain times of the year it seems as though the hairs were actually
floating about in the air. At the time of the caterpillar’s change
of skin, and particularly at the time of the spinning of the cocoon
and the final change, certain of these hairs appear to become loos-
ened in such a way that they are carried by the wind.” Others
report that these poisoned hairs may collect on clothing hanging on
the line, to the intense annoyance of those who wear it.

The readiest and most obvious means of controlling the brown-
tail moth, and certainly the easiest one, is the collection and destruc-
tion of the winter nests after the leaves have fallen. After April
the only practical remedy is spraying the trees with an arsenical
mixture. The young caterpillars are readily enough destroyed with
arsenate of lead, but the older ones become resistant to poison
sprays, and as much as five pounds of the arsenate to a barrel of
water has been found necessary to kill the full-grown caterpillar.

When this insect appears within our borders it will be most
destructive in parks and towns and forest plantations, since these
are not regularly sprayed and will require a special treatment to
protect them. It will also aid the San Jose scale in putting out
of business the neglectful or indifferent orchardist, but the business
fruit grower, who values his property and takes care of it as well
as he can, will have much less to fear from this insect, since his
ordinary spraying operations will be practically certain to destroy
it as it enters his orchard. The fact, however, that the full-grown
caterpillar requires a heavier insecticide treatment than does the
codling-moth and the canker-worm, for which most of our spray-
ing is done, may make it necessary to go over the orchard in winter
to remove and destroy the hibernating colonies.

The gypsy moth may be more briefly considered, altho it
is even a more destructive pest than the brown-tail, especially for
the reason that it eats the leaves of evergreens—trees which are
often killed by a single defoliation. It is conveyed to distances in
the caterpillar stage only by accident. Passing wagons, automo-
biles, trolley cars, or even railroad trains, may carry the cater-
pillars to uninfested districts, but in this way its spread is slow,
especially as all possible measures are being taken in infested dis-
tricts of New England to keep the roadsides free from the pest,

19

and thus to reduce to a minimum the possibility of an extensive
spread.

The caterpillar of the gypsy moth (Fig. 16) is a voracious feed-
er, eating the leaves of nearly every kind of tree or shrub, and de-
youring sometimes also grasses and field and garden crops. The
very fact that it spreads but slowly makes it locally all the more

Fig. 16. Gypsy Moth, Porthetria dispar, larve. Natural size.
(Connecticut Experiment Station.)

injurious, since it accumulates in enormous numbers upon infested
localities. Forests, orchards, gardens, parks, and street shrubs and
trees may be stripped of every leaf between the first of May and
the middle of July.

The insect winters in the egg stage, the eggs being plastered
in conspicuous masses (Fig. 17) on the trunks of trees ‘and on va-
rious other objects. They may readily be destroyed by touching
them with a mixture of creosote oil, 50 percent, carbolic acid, 20
percent, turpentine, 20 percent, and coal-tar, 10 percent, in sufficient
quantity to soak the mass. The caterpillar may also be killed on the
trees with arsenical poisons, but these must be applied in unusual
quantities, since the gy psy moth is not readily poisoned in the cater-
pillar stage. Five pounds of arsenate of lead to fifty gallons of
water w ill kill the young, but even this can not be depended upon
for the full-grown caterpillars. These are about three inches long,
of a sooty or dark gray color. Along the back is a double row

20

of blue spots, followed by a double row of red spots, and the back
is marked with yellow. The cocoon is formed among the leaves
like that of the brown-tail and the moths appear from the middle
of July to the middle of August. The male is bluish-yellow, ex-
panding about an inch and a half, and the female (Fig. 17) is

Fig. 17. Gypsy Moth, Porthetria dispar; female moths, laying eggson bark. Naturalsize,
(Connecticut lsxperiment Station.)

nearly white, somewhat spotted and barred with black. Its wing
expanse is about two and a fourth inches. The female is very slug-
gish and so heavy that she can not fly; but the male is an active
flier.

The oval egg masses, about one and a half inches long by
three-fourths that in width, are laid in summer on the trunks of
trees, on fences, on the sides of houses, and in various other places.
Large holes in old trees are often found filled with them. The
caterpillars feed principally at night, especially after they reach
some size, and they seek to hide during the day, often coming down
upon the larger limbs and trunk of the infested tree in search of
hiding places. This habit has led to the use of bands of burlap
tied around the trunks of trees, under which the caterpillars may
rest during the day and where they can be easily destroyed by hand.

The probabilities of widespread destruction to forest, park, and
orchard properties by these insects are greatly reduced by the truly

21

tremendous and unexampled work being done by the United States
Department of Agriculture and the state of Massachusetts in bring-
ing from Europe the native parasites of these insects. This work
is making successful progress, and it is all the more hopeful because
the parasites of both these species seem to keep them substantially
in check in the Old World, where they rarely become seriously
destructive.

Tue Forest TENT CATERPILLAR
(Malacosoma disstria Hbn.)

There occasionally appears in the forest region of southern
Illinois an overwhelming eruption of caterpillars which denude
large areas of woodlands, especially the oaks and the mapies, and
the black and sweet gum trees, and thence invade orchards, parks,
and town premises, carrying the same destruction to fruit and shade
trees generally. This is one of the species which moves in masses
such as actually to delay the passage of railroad trains, piling up

__Fig.18. Baltimore Oriole attacking nest of Forest Tent Cater-
e pillar, Ma/acosoma disstria. (New Hampshire Experiment Station.)

on the rails several inches deep. It is known to entomologists as
the forest tent caterpillar, but in the South it is commonly called
“the caterpillar” simply. The name of “‘tent caterpillar” is, in fact,
inappropriate for it, since it spins but little and never makes a tent.
It is closely allied, however, to the common tent-caterpillar of
eastern orchards and has received its common name because of this
resemblance.

When full grown (Fig. 19) it is about two inches long and a
quarter of an inch thick. It is of a brownish general color, and is
conspicuously marked with a series of whitish or cream-colored
spots down the middle of the back. On the upper part of each side

Fig. 19. Forest Tent Caterpillar, Malacosoma
disstria, larva. Natural size.

is a rather broad blue line edged above and below with a
yellowish-brown line. When disturbed it drops from the branch
‘and hangs suspended in mid-air by means of a fine thread
spun from the mouth. In moving about on the tree these cater-
pillars follow each other in single file. They feed mostly in the
tops of the trees, often eating out the central part of the base of a
leaf, allowing the remainder to fall to the ground. When preparing
to molt, they mass together on the limbs and may continue thus for
a day or two. They often form similar masses in stormy weather
and in general when at rest. The eggs (Fig. 20) are laid in a
thick hard band around a twig and covered with an impervious
varnish. From these the young hatch in early spring, sometimes
before the appearance of the leaves on which they depend for food.

Fig. 20. Forest Tent Caterpillar,
Malacosoma disstria; e, egg ring re-
cently laid; g, hatched egg ring.
Slightly enlarged. (Cornell Ex- Fig. 21. Forest Tent Cater-
periment Station.) pillar, Malacosoma_ disstria:

, m, male: 7,female. Natural
size. (Cornell Experiment
Station.)

23

They are capable, however, of fasting for a considerable time with-
out injury, and they may even survive the destruction of the leaves
by late frosts. They scatter for pupation late in May or early in
June, spinning cocoons which they fasten among clusters of
leaves or exposed on fences and in other similar situations. There
is but a single generation in a year. The parent moths (Fig.
21) measure about an inch and a quarter across the expanded
wings. The general color is brownish-yellow and the fore wings
are marked by two straight dark brown lines which cross them
obliquely, parallel with each other and‘the hinder edge.

Trees may be protected by spraying with arsenical poisons
shortly after the young caterpillars begin to appear, or by clipping
off in winter the twigs bearing the conspicuous belts of eggs and de-
stroying these by burning. Even overwhelming hordes may be ar-
rested by surrounding the tree trunk with a band of cotton batting
about four inches wide, tied around the middle with a string, the
upper part being then turned downward over the string. Or, the
trunk may be surrounded with a band of printers’ ink applied as
described in the article concerning the common canker-worm

(p. 488).
THE CoMMON CANKER-WORM, OR SPRING CANKER-WORM
(Paleacrita vernata Peck)

The common canker-worm is best known as a pest of the apple
orchard, but it is sometimes even more destructive to elms (Fig. 22
than to apple-trees. It feeds also on cherry, at first eating small
holes thru the leaves, but when larger devouring the whole leaf ex-
cept the midrib and some of the coarser veins. Modern methods
of orchard management require a regular and frequent spraying
with arsenical poisons as a protection of fruit against the codling-
moth, and this has the incidental effect—often ummnoticed by the
orchardist—of speedily killing off any colony of canker-worms
which may have chanced to make a start in the orchard. Hence
it is only neglected orchards, or those not in bearing either because
too young or by reason of a crop failure for the year, which are
liable to serious canker-worm injury.

With the elm, however, the case is different. The canker-worm
lives on this tree as willingly and successfully as on the apple. Elms
are rarely sprayed in Illinois, and if the canker-worm once comes
to infest them there is no natural end to the injury except the death
of the tree, unless, indeed, the parasites of the insect and other
natural checks on its increase may happily suppress it before that
event.

24

The spraying of large elms is, of course, a difficult and expen-
sive operation, and canker-worms are less susceptible to arsenical
poisons than many other insects. There is, however, a much cheaper
and more convenient method of protecting the elm, by which ad-
vantage is taken of two features in the economy of the insect.
When the caterpillars are full grown they leave the tree to pupate
in the earth, and the female moth emerging, being wholly without
wings, can only reach the tree to lay her eggs by climbing up the

Fig. 22. Injury toelms at Calamus Lake, Niantic, Illinois,
by common Canker-worm (Paleacrita vernata).

trunk. If this is encircled at the proper time by a sticky band im-
passable by her or by young canker-worms just hatched from the
egg, the tree is virtually secure against canker-worm injury except
as worms may reach it from neglected trees with which its own
branches interlace.

Altho the female canker-worm (Fig. 23, b) is wingless, the
male (Fig. 23, a) has two pairs of rather large, thin, ashy .or
brownish-gray wings, the first pair with a broken whitish band near
the outer edge and three interrupted brownish lines between that
and the body. There is also a short oblique black mark near the
tip of the wing, and a black line at its edge at the base of a fringe
of hairs. The eggs (Fig. 24, b) are about .03 of an inch long, oval
in outline, and of a pearly luster at first, changing to yellowish-
green with a golden, greenish, or purplish iridescence. They are

25

laid in irregular masses, often as many as a hundred together, and
usually hidden in crevices of the bark of trees.

The female comes out of the ground to lay her eggs from
February to April, the date varying with the latitude and the sea-
son. The young caterpillars appear about the time that the apple-
tree unfolds its leaves, commonly, in this state, in April or early
May, and they usually get their growth in about a month from the
time when they issue ‘from the eggs. They then go into the ground
to a depth of two to five inches, each one in a small cell, where
they change to the chrysalis, remaining there until the following

Fig. 24. Common Canker.-

Fig. 28. Common Canker-worm, Paleacri/a worm, Paleacrita vernata: a,
ernata: a,adult male; b,female; c, portion larva; 6, cluster of eggs, nat-
f female antenna; d, joint of abdomen, en- ural size, with one enlarged; ¢,
arged; ¢, ovipositor. side view of one of the seg-

ments, @, back view of same,
both enlarged.

winter or early spring, when the change to the adult insect takes
place. There is thus but a single generation produced each year.
The canker-worm is widely distributed thruout the country and
may occur in destructive numbers in any part of Illinois. Its feeble
power of locomotion prevents its rapid spread in any locality, but
by concentration of its injuries it is the more destructive where it
does occur.

In its injurious or caterpillar stage (Fig. 24, a) it is readily
recognized. It has a long and slender form and the habit of a
“looper” or measuring worm. When not eating it usually adheres
only by its hinder prolegs, extending the body from this point of
support at an angle of about 45 degrees. As it is colored much like
the bark of a tree, it then has the appearance of a stubbed twig. It
also has the habit of spinning down from the tree at the end of a
thread, particularly if the branch is jarred or shaken. Both the just-
mentioned habits are doubtless advantageous to it; the first by con-
cealing it to some degree from the observation of birds and the
second by putting it beyond their reach. The full-grown canker-
worm is about nine-tenths of an inch in length and may vary from
greenish-yellow or gray to dusky or even dark brown, with paler
stripes along the sides. A close examination will show also two
light lines running close together along the middle of the back.

2

26

The young are usually olive-green. The wingless female, with its
small gray body from a quarter to two-fifths of an inch in length
and its rather long legs, gives more the impression of a spider than
that of a moth. The chrysalis is pale grayish-brown, with a dark
green tinge on the wing sheaths, and measures about a third of an
inch in length.

This insect has not recently been abundant in Chicago, but its
capacities for injury are well illustrated in a recent attack on elms
at Big Rock, Kane county. Some ten years ago it was generally
prevalent thruout the south-central part of the state, both in
towns and in forests, to which it had apparently escaped from neg-
lected orchards, although in some cases orchards were invaded in
turn from adjacent forests. A most threatening attack was made
on the magnificent old elms of Jacksonville, but a vigorous cam-
paign, first of spraying and later of the application of adhesive
bands, presently brought the outbreak under control.*

A cheap and available band for the trunk of a tree is made by
laying around the trunk first a strip of unglazed cotton batting
two or three inches wide and over this a four- to six-inch strip of
tarred paper tied around the middle with ordinary wrapping twine.
Upon this paper belt should be spread a layer a quarter of an inch
thick of cheap printers’ ink with which a small amount of car wheel
oil has been mixed, just enough to make it easy to spread. If the
tarred belt becomes slightly hardened by exposure so as to permit
an insect to cross, it may be made sticky again by brushing it with
a little of the same kind of oil. The cotton batting beneath the
paper is necessary to keep the young canker-worms or the female
moths from crawling up behind the paper where the roughness of
the bark would give them passageway. These bands should be
placed on the tree as early as the middle of February or the first
‘of March, the time varying according to the latitude, and they may
be safely removed by the middle of June. The cost of the bands
will approximate ten cents a tree.

If the canker-worms have already ascended the tree, it is some-
times necessary to spray the leaves with an arsenical poison, which
may be either arsenate of lead or Paris green, the latter at the rate
of one pound of the poison and one pound of lime to seventy-five
gallons of water. If the arsenate of lead is used, three pounds of
it dissolved in fifty gallons of water will kill even the full-grown
caterpillars.

*The Canker-worm on Shade and Forest Trees. By S. A. Forbes. Twen-
ty-second Report State Ent. Ill., page 130.

Bi
THe Litac Borer

(Podosesia syringe Harris)

Among the borers whose instincts lead the female to choose,
for the deposit of her eggs, scars or injured places on the bark of
trees and shrubs, with the effect greatly to increase the injury and

Tig. 25. Trunk of ash in one of the parks in Chicago, showing injury
by the Lilac Borer, Pouosesia syringe.

to prevent its healing, is a species commonly known as the lilac
borer (Podosesia syring@), because it was first noticed to infest
lilacs. It is much more important, however, by reason of its in-
juries to various species of true ashes,* and to the mountain ash,

*It has been found injurious to the lilac (Syringa sp.), to the mountain
ash (Sorbus americana), and to the white, green, and English ashes (Fraxr-
inus americana, lanceolata, and excelsior).

Fig. 26. Trunk of ash, in one of the parks in Chicago, showing injury
by the Lilac Borer, Podosesia syringe.

on the trunks and branches of which it produces large, rough, scar-
like outgrowths from knots, roughened places, or wounds, by un-
dermining the bark and boring into the wood. (See figures 25 and
26. )

The eggs are laid in summer in masses on rough, scarred, or
knotty places. They hatch in about six days and the young borers
at thru the bark into the outer layers of the sapwood, where
they mine irregularly about, penetrating the harder wood and go-
ing to the center of small branches. (Fig. 27.) In fall, when they
are nearly or quite full grown, they make a hibernating cell by
plugging up the burrow both before and behind with frass, and
there they pass the winter as larve. They do practically no bur-

29

rowing in spring, but pupate in April or the first part of May. As
a preparation for pupation, they burrow outward and cut their
way thru the bark, leaving only a thin outer film to close the pupal
cavity. By means of short teeth with which each segment of the
abdomen is armed, the pupa, when mature, works its way out of

Fig. 28. Lilac Borer, Podo-
sesia syringe, larva. About
5 times natural size.

Fig. 27, Lilac Borer, Pod-
osesia syringe. Burrows
in ash made by larve.
Slightly reduced.

its gallery until it projects some three-quarters of an inch. The
winged insects, altho moths, closely resemble wasps in movement,
color, and form. They make their appearance from the latter part
of April to the middle of June in central and northern Hlinois.
The borer or larva (Fig. 28) is very variable in length. It is
white, yellowish anteriorly, the head of a bright mahogany color,
becoming very dark at the mandibles, which are stout, broad, and
provided with five teeth. The segments of the body are distinctly

30

marked, somewhat flattened, the first segment reddish and leathery
above, the last with a broad yellowish patch.

The moth (Fig. 29) has a black head, a deep brown thorax
more or less marked with bright chestnut-red, and a black abdomen
sometimes marked with chestnut, but sometimes with a small yel-
low spot on each side of the fourth segment, or with the segments
banded with yellow. The femora are black, the anterior pair of
the tibia orange, the middle and hind tibize black with orange bands.

Fig. 29. Lilac Borer, /’odosesia syringe, adult.
Slightly enlarged.

The tarsi are yellow, the hind pair with a black band above. The
fore wings are deep brown, with a violaceous luster and usually
with a rusty red dash on, the outer part. At the base is a transpar-
ent streak. The hind wings are transparent and yellowish, the
veins, discal marks, and margins deep brown, sometimes tinged
with red.

The spread of the wings is from an inch to nearly an inch and
a half, the females being considerably larger than the males.

This insect is very abundant and destructive, especially to the
green ash in Chicago parks, and has been bred by us also from the
white ash at Kankakee. Its injury is very noticeable and character-
istic, especially on the trunks of small trees. Sometimes the smaller
branches break off at the point of injury, but this does not usually
happen until after the moth has escaped. George D. Hulst says,
writing of these insects in New York: “In this section they are
very destructive to both lilac and English ash. Large shrubs of
lilac are now very rarely seen, and the English ash is being rapidly
exterminated. In the latter I have seen the wood completely rid-
dled with the holes made by the larve and the entire tree dead.”

To check the multiplication of the species and the spread of the
injury it will be sufficient to cut away and burn infested branches:

31

and trees in winter. It may also be practicable to protect trees espe-
cially exposed by painting rough, knotty, and injured places on the
bark with a poison mixture Eontmonty used by orchardists to prevent
infestation by ordinary borers. A number of substances are avail-
able for this purpose, the simplest of which, perhaps, is a mixture
of soft soap and soda, with the addition of Paris green. The fol-
lowing is a convenient formula: To a saturated solution of wash-
ing soda add soft soap sufficient to make a thick paint, and to each
ten gallons of this wash add a pint of crude carbolic acid and half a
pound of Paris green. This may be painted thickly upon scarred,
roughened, or knotty surfaces in April and early May and renewed
as necessary until August.

Two PopLar Borers
(Memythrus tricinctus Harris)
(M. dollii Neum. )

Two boring caterpillars, similar in appearance, but differing in
the larval or boring stage mainly in size, infest poplars in this state
to an injurious degree. They are most destructive to young nursery
EEES, particularly to the balm of Gilead (Populus candicans), but
the Carolina poplar (P. deltoides), Figure 30, is also sometimes
badly infested. They are generally present thruout Chicago, often
infesting trees which are likewise injured by a boring larva, Cryp-
torhynchus lapathi, discussed on p. 40. ‘They have also been found
by us in park and street trees in several [linois cities and towns
from Centralia northward. In the case observed by us in Chicago,
the eggs of one of these species, which one we do not know, were
deposited July 22, mostly in a crevice of the bark or in the neigh-
borhood of a bud, and young larve were first seen July 26, altho
some of these had apparently hatched at least a week before. The
borers winter in the larval stage in the wood, pupate in spring, and
come out as winged moths in June and July—at various dates from
June 18 to July 26, if we may judge by results obtained in our in-
sectary. Froma willow in Cook county a specimen of M. tricinctus
was bred which emerged July 2.

The boring larve are whitish caterpillars, with brown or yellow-
ish heads and a smooth neck shield. The two species are most easily
distinguished by the markings of the head and by the number of
hooks on the abdominal legs. In M. tricinctus the head is yellowish
and mottled with large patches of brown, while the abdominal feet
have from eighteen to twenty-two hooks in a row. In MW, dolli

32

(Fig. 32) the head is brown with large darker patches on the sides,
and a black band or blotch between the antennz. The abdominal
feet have ten to fifteen hooks in each row. Both these species are

a eg nna Samet ae ed
5 !

Fig. 30. Small poplar infested with sesiid borers (Memythrus).

distinguished from some other borers of their family by the fact -

that the first segment of the thorax bears two oblique dark marks,
approaching each other behind.

Ss

33

The winged insects are readily distinguished by a comparison of
the wings and abdomens. In tricinctus (Fig. 35) the fore wings
are violaceous-black, the hind wings are transparent, and the ab-
domen is black with three or four yellow bands. In dollii (Fig.
36) the fore wings are brown, the hind wings are brown and

Fig. 31. Poplar Borer
Memythrus tricinctus or
dol.it, egg. Greatly en- Fig. 32. Poplar Borer, Memythrus dollii, larva.
larged, About 3 times natural size.

opaque, except at the base, and the abdomen is brown, sometimes
with one or more yellow bands.

In our work with these borers it was not at first known that two
species were concerned, and the larve were not distinguished 1n our
notes. It was only when the adults appeared that the specific dis-
tinctions were established.

Fig. 34. Poplar Borer,
Memythrus tricinctus or M.
dollii, anal end of pupa.
Greatly enlarged.

Fig.33. Poplar Borer,
Memythrus tricinctus or
M, dollit, pupa. About
3 times natural size.

34

Fig. 35. Poplar Borer, Memythrus tricinctus,
adult female. About twice natural size.

A third species, allied to the two above mentioned, but more
commonly found infesting ninebark (Opulaster opulifolius), has
been once bred by us from poplar at Chicago.

th

Fig. 36 Poplar Borer, Memythrus dollii, adult. About
twice natural size.

A VIBURNUM BORER
(Sesia pictipes G. & R.)

A boring caterpillar, somewhat larger than that described from
ninebark and dogwood, but otherwise extremely similar, has been
found doing considerable damage to viburnum shrubs in all the
parks of Chicago, and, in one case, to wild black cherry at Riverside.
It burrows beneath the bark, frequently killing the branches. It
spends the winter in the larval stage, and has emerged in our breed-
ing cages during the latter part of June, from the twentieth to the
twenty-fourth. Elsewhere it is reported to emerge during June and
July. The species is known also from plum, cherry, beach-plum,
peach, Juneberry, and chestnut, and has been bred from the black-
knot of the plum.

The placing of the eggs has not been noticed by us, but another
observer, Dr. Bailey, found a cluster of them, ninety-two in number,

35

on the under surface of loosened bark a few inches from the root of
a badly infested pium-tree.

The removal and destruction of infested branches at the proper
time of the year, that is, during the winter and spring, is the only
measure practicable for the control of this pest.

The winged insect has a blue-black head, thorax, and abdomen,
the thorax with a narrow pale line each side, and the abdomen with
a narrow pale yellow ring on the second and fourth segments, en-
circling the body completely on the latter. The fore wings are
transparent, with very narrow blue-black margins, and a narrow,
straight, discal mark. The inner margin is sometimes scaled with
pale yellow. The hind wings are transparent, with a very narrow
outer margin and no discal mark. The spread of the wings is from
15—26 mm., the smaller specimens being males.

THE Maré Borer
(Sesia acerm Clem.)

The worst of the borers of the maples, both hard and soft, very
common and destructive to soft maples in Chicago, and common
also in towns thruout the state, is a white or nearly white caterpillar
(Fig. 37, a) about half an inch long when full grown, with a yel-
low head and a neck shield of a paler tint. It is especially injurious
to young trees, but usually originates in some surface injury which
attracts the parent moth in search of a place of deposit for her eggs.

Fig. 37. Maple Borer, Sesia acerni: a, a,
larve; b, 6, b, cocoons; ¢, adult; d, pupal
skin left in mouth of burrow.

&6

It burrows mainly just beneath the bark, where it can be found and
destroyed in fall or early spring. It comes to maturity in May or
June, eats its way nearly thru the bark, and pupates there. We
collected the adult in considerable numbers, at electric lights, in Ur-
bana, from May 18 to June 3, 1887. When ready for its transfor-
mation the pupa wriggles partly out of its burrow, and the adult
insect escaping leaves the empty pupa-case still sticking in the open-
ing, which is about an eighth of an inch across. (Fig. 37, d.)

» The adult is a handsome wasplike moth (Fig. 37, c; Fig. 38)
with thin transparent wings, a slender yellow body banded and
trimmed with red, and a brushlike tuft of hairs at the tip of the

Fig. 38. Maple Borer, Sesia acern?, adult. About 3 times
natural size.

abdomen. The eggs are laid chiefly in rough or injured places, al-
most wholly in the trunk of the tree, and not in its branches. The
effect of the injury is to kill the bark undermined, and to enlarge
surface wounds and prevent their healing, converting them into
permanent, rough, and very unsightly scars. Sometimes the tree
is killed by a girdling of the trunk.

To prevent attack by these borers the tree should be protected
from injury, and such wounds as it receives should be painted over
or covered with grafting wax. Dr. Felt, State Entomologist of
New York, says that “the deposition of eggs could probably be pre-
vented to considerable extent by treating the trunks of trees about
the middle of May with a wash prepared as follows: ‘Thin one
gallon of soft soap with an equal amount of hot water and stir in
one pint of crude carbolic acid (one-half pint, refined), let it set
over night and then add eight gallons of soft water. Apply thor-
oughly to the trunk, especially about all crevices and wounds, from
the ground to about six or eight feet high, and renew if necessary
before the middle of June.” As the borers work near the surface,
they can be easily dug out and destroyed in fall.

37

THE NINEBARK BORER
(Sesia scitula Harris)

Dogwood and ninebark shrubs (Cornus sp. and Opulaster opuli-
folius) in the Chicago parks are generally infested, and often seri-
ously injured, by a boring 01 girdling caterpillar (Fig. 39) which
works just beneath the bark, mainly at the junction of the branches

Fig. 39. Ninebark Borer, Sesia scitula larva.
About 3 times natural size.

or in the neighborhood of an old dormant bud. The burrows of the
borer sometimes extend lengthwise of the branch, and sometimes
girdle it near its origin. In 1908 nearly every shrub of the ninebark
in Washington Park was infested, and many of the branches were
killed by this larva. The species also infests the chestnut, and has
been bred from galls on twigs of the oak.

The creamy white larva, half an inch long in September, passes
the winter in its burrows, and emerges, according to our observa-
tions, in late June or in July. The head is brown, darkening almost
to black towards the mandibles. The prothorax is slightly brownish,
with two oblique brown markings on its posterior half. The re-

Fig. 40. Ninebark Borer, Sesia scitula, adult female.
About 3 times natural size.

maining segments are creamy white, except the last, which is pale
reddish-brown.

The winged insect (Fig. 40) is deep blue-black on the thorax
and abdomen, the former with a yellow line and a yellow patch on
each side, and_the latter with a yellow line at its base and, in the

38

male, a narrow yellow ring on the second and fourth segments,
broadening below cn the fourth to cover the whole surface. In the
female the fourth segment is yellow both above and below. The
head and antennz are black, the femora blue-black, and the tibiz
yellow. The fore wings are transparent, except the borders and
the discal mark, which are blue-black. The outer margin is marked
with yellow rays. The hind wings are transparent, with very nar-
row blue-black margins. The spread of the wings is from 18—22
mm.

This insect can evidently best be destroyed by cutting out and
burning infested branches in winter or early spring.

THe BaG-worM
(Thyridopteryx ephemerefornus Harris)

One sometimes sees hanging from the branches of trees, in late
summer or in fall or winter, especially in the southern part of the
state, rough excrescences, about two inches long, shaped somewhat
like a spindle full of yarn, soft to the touch, and more or less covered
with pieces of dead leaves which seem to be woven into their web-
like substance (Fig. 41, f). In summer it may be further noticed

Fig. 41. Bagworm, Vhyridopteryx ephemereformis: a, larva; 0
and ¢c, pupa, side and back views; d, adult; e, case containing the
eggs; J, larva in case; g,eggs. Natural size.

that these spindle-shaped sacks can creep along the twig, and that
there projects from the end nearest the twig the head and front part
of a caterpillar, the remainder of which is enclosed in the protect-
ing bag. In winter this is hung to the tree by a rather tough liga-
ment composed of material like spider-web. An examination of
these peculiar bodies at that season will show either that they are

39

virtually empty, or that they contain a mass of soft yellow eggs.
GEig.Aq, ¢.)

The insect known as the bag-worm, to which these constructions
are due, is in several respects one of the most curious in Illinois.
Altho the parent form is a moth, the female is wingless and naked
(Fig. 41, c), looking more like a grub than a moth, and the wings
of the male, instead of being covered with scales, are smooth and
transparent, somewhat like those of a wasp. (Fig. 41, d.) The
caterpillar infests a considerable variety of both fruit and shade
trees, including among the latter evergreens (especially red cedar
and arbor-vite, Fig. 42) and several kinds of deciduous trees.

Pe eee "

im |
Se. |

i
i
|

ee Ee eg

Fig. 42. Bag-worm, Thyridopteryx ephemereformis, cases hanging on arbor-vite twig.
(Ohio Experiment Station.)

It does its injury by eating the leaves of trees, and its numbers are
often such that they may take virtually every leaf off a tree of
considerable size.

The eggs, contained during the winter in the bag-like cases on
the trees, hatch the following May or June, and the young caterpil-
lars begin at once to spin for themselves small conical cases (Fig.
41, g) to which they fasten pieces of leaves from the tree upon
which they are feeding. As they grow these cases are enlarged
until they take the form and dimensions already described. The
caterpillars (Fig. 41, a) travel but slowly, and seldom leave the
tree upon which they were hatched until they are about full grown,

40

when they are likely to spin down and wander about. They change
to the chrysalis (Fig. 41, 6) within the bags, which they fasten to
the twigs of the trees as a preliminary, but the grublike female
moth, destitute of wings and with only minute and useless legs,
deposits her eggs within her native sack, works her way out of it,
drops to the ground exhausted, and dies. The winged males (Fig.
41, d) appear in September and October, and soon thereafter the -
eggs are laid.

The bag-worm is a southern insect in its general range, and is
rarely seen in northern Illinois. It increases in importance south-
ward, and in southern Illinois is often a troublesome pest. In a
general trip to eighteen towns, well distributed thruout the state,
Mr. J. J. Davis, in 1910, found the bag-worm in four out of six
southern Illinois towns visited, but in no others.

The simplest method of destroying these insects is to collect the
bags during the winter and burn them—a thing easily done with the
aid of pruning shears if they can not be reached by hand. If this
measure is neglected, infested trees may be cleared by spraying them
with arsenical poisons soon after the hatching of the eggs—the latter
part of June or early July. A pound of arsenate of lead to forty
gallons of water is a safe and effective poison.

THE PoPLAR AND WILLOW BorER
(Cryptorhynchus lapathi Linn. )

The weeping willow, the Carolina poplar, the balm of Gilead, and
the red birch are ornamental trees of sufficient popularity to make
the existence of any insect pest destructive to them a matter of gen-
eral interest. The Carolina poplar especially has had an enormous
distribution of late years in Illinois towns, largely because of the
ease and certainty with which it may be raised, and the rapidity with
which it grows in our soils.

The advent into this country nearly thirty years ago of a
European snout-beetle well known in the Old World as a destroyer
of alders, poplars, and willows, and occasionally injurious to birches
also, has seriously endangered our American plantations of these
trees. Detected first in New York in 1882, and found on Staten
Island in 1886, it appeared in considerable numbers near Buffalo by
1896, and the following year was reported as abundant in Boston,
Mass., and very destructive there to willows and poplars of all kinds,
and to the red birch. By 1rgor it had reached northeastern Ohio; in
1903 it was found in two Wisconsin nurseries ; and in 1904 it was re-
ported from North Dakota in poplars lately brought into that state
from New York. In Illinois it was first seen by us in 1908 in Caro-
lina poplars at Chicago; but once detected there it was soon found
to be generally distributed and very destructive to both poplars and
willows in all parts of the city. (Fig. 43.) It has not yet occurred,

41

to our observation, elsewhere in Illinois. Wherever it appears it
multiplies locally, but makes a slow spread, a fact apparently due to
the sluggishness of the parent beetle, which, although provided with
wings, makes extremely little, if any, use of them. In consequence

Fig. 43. Small poplar tree in Chicago showing dying of upper
branches re-ulting from attacksof the Poplar aud Willow Borer,
Cryptorhynchus lapathi.

of this fact, an infested grove may be nearly destroyed before an-
other, near at hand, becomes even infested. It extends its range
most readily along watercourses by means of the willows and cot-
tonwoods with which our streams are likely to be fringed. Its
spread to distant points seem to have been mainly, if not altogther,
by way of the nursery trade, especially that in poplars and willows
of various kinds. These facts make it particularly important that

42

the signs of its presence should be generally known, in order that
it may be promptly recognized and suppressed upon its appearance
in any new locality.

Injury by this borer may be suspected when the general health
of a tree is evidently affected, where there are dead patches of the
bark, irregularly cracked open (Fig. 44, 45), or where openings in

Fig. 44. Injury by Poplar and Willow Borer,
Cryptorhynchus lapathi.

the bark give exit to a soft excrement like moist sawdust naixed
with fine splinters. The burrows beneath the bark, made chiefly in
the cambium layer, are irregular in direction, sometimes girdling a
small tree, and show nothing of the symmetrical pattern made by
many borers which undermine the bark. Those of the older larve
dip into the wood, usually reaching the center of the branch unless
this is large. These deeper burrows finally become filled with
powdered wood and splinters, except a chamber at the farther end
in which the larva pupates. In the active boring stage these in-
sects are soft, yellowish, fleshy, cylindrical, footless grubs (Fig.
46) with a pale-brown head and darker mouth-parts. They are
half an inch long when they reach full size, which is about the last
of June for those most advanced. At this time, however, young
larve may be found under the bark down to a fifth of an inch in
length.

The adult beetles (Fig. 47) begin to appear in July, and con-
tinue abroad at least until October. They are well marked and
easily distinguished insects, a little more than a quarter of an inch

43

long, thick-bodied, with a roughened and punctured surface, and a
stout curved beak projecting downward from the head. The gen-
eral color is dark sooty brown, more or less specked and spotted

|
|
|

Fig. 46. Poplar and Willow Borer, Crypto-
rhynchus lapathi, larva. About 4 times natura]
size.

Fig. 45. Injury by Poplar and Wil-
low Borer, Cryplorhynchus lapatht.

with gray, and there is a very conspicuous large patch of light gray
on the hinder end of the wing-covers, contrasting strongly with the
adjacent colors. The sides of the prothorax are gray, and there is
a pair of rather definite oblique gray marks just behind the front
outer angle of each wing-cover. The beetle is slow and lumbering
in its movements, and when disturbed drops to the ground like a
curculio, without attempting to fly. It feeds upon the cambium
layer of the younger branches, which it reaches by puncturing the
bark with its snout. It lays its eggs in the older bark, mainly of
branches from two to four years old. This the female does by
first eating downward into the bark by means of the jaws at the
tip of her snout, taking half an hour or more to hollow out a cay-
ity in which the egg is concealed. She then turns end for end, and
leaves an egg in the chamber thus made, and presently moves away
to repeat the process at another point.

The young hatch mainly in August and September, penetrate at
once to the cambium layer, and hibernate there while most of them
are still very small. The following spring they continue to work in
the cambium until nearly ready for pupation, when they enter older
wood.

44

The dependence of the beetle for food upon the bark of the tree
which it infests has suggested the use of poisons for its destruction,
and some tests made at the New York Agricultural Experiment
Station show that the ordinary arsenical poisons applied as a spray
will destroy it. Arsenate of lead is the best of these for the pur-
pose, because of its adhesive quality. Trees to be protected should
be thoroly sprayed at intervais of about a fortnight, beginning

Fig. 47. Poplar and Willow Borer,
Cryptorhynchus lapathi, adult. Length,
about one-fourth inch.

with the middle of July and continuing thru August. | Moder-
ately infested trees may be saved by cutting out the grubs and cov-
ering the wound with tar. Badly infested trees should be taken out
and burned, either during the winter or before July 1 of the follow-
ing season. Nursery trees infested by this insect should be un-
hesitatingly destroyed, since they are far worse than worthless, and
are the principal means of conveying the species to places not pre-
viously infested by it.

THE DoGwoop TWwIG-GIRDLER
(Oberea tripunctata Swederus)

Among the insects whose nice and elaborate instincts connected
with the placing of their eggs are the wonder of entomologists, we
must class the twig-girdlers, for their careful preliminary opera-
tions are such as to suggest a knowledge of vegetable physiology
and a prevision of the possible difficulties in the way of the de-
velopment of their young certainly quite beyand the powers of
insect intelligence, and an unsolved puzzle if regarded as a product

45

of natural selection. The twig-girdler of the dogwood is an ex-
ample.

This is a small, cylindrical beetle (Fig. 48), about half an inch
long and less than an eighth of an inch in diameter, which prepares
a chosen twig for the recepticn of the egg by first cutting a groove
around it a few inches from its tip in such a way that the twig

Fig 48. Dogwood Twig-gird-
ler, Oberea tripunctata, aault.
About 5 times natural size.

Fig. 49, Cornus twig

- girdled by Dogwood

Twig-girdler, Cbherea tri-

punctata, and part en-

larged, showing egg in
position.

presently breaks off at this point, and afterwards making a second
girdle, not so deep as the first, and from two to four inches farther
back. (Fig. 49.) It then makes two parallel cuts, about half an
inch long, lengthwise thru the bark between the two girdling in-
cisions, and at the proximal end of these makes a short transverse
slit in a way to form an angular flap, beneath which it pushes its
egg. The effect of all this surgery must be to stop the growth of
that part of the branch operated on, and to check the flow of sap
to the section in which the egg is laid.

46

These operations are distributed, in northern Illinois, over the
month between the middle of June and the middle-of July. The
eggs hatch within a week or ten days, and the young larve pene-
trate the twig, burrowing downwards towards its point of attach-
ment, and making holes to the surface at intervals thru which to
discharge their excrement. After a time the larva cuts off, from
within, the part of the twig thru which it has made its way, and
plugs the open end of the burrow with coarse bits of frass. It oc-
casionally repeats this plugging, pursuing its way until winter
overtakes it, and pupating within its burrow from the middle to the
latter part of the following May, first, however, commonly cutting
off the branch obliquely and plugging the cavity a little beyond its
pupal cell. (Fig. 50, 51.) The adult emerges during the latter

Fig. 50. Dogwood Twig
girdler, Oberea tripunc
tata, larva. About 4
times natural size.

Fig. 51. Cornus twig
with burrow of Dog-
wood Twig-girdler, Obe-
rea tripunciata; a, end
obliquely cut off by
larva; 06, f, plugs of
fracs; c, openings made
by larva and plugged
up later; d, cocoon of
ichneur oned parasite;
e, remains of parasitized
Oberea larva.

47

half of June, eats its way thru this terminal twig, and feeds dur-
ing its short life on the leaves of the infested tree, making oval
holes thru the leaves along the course of the veins. (Fig. 53.)
The presence of this borer is commonly first betrayed by a with-
ering of the leaves at the tip of the girdled shoots. It is a rather
common pest in the Chicago parks, where it has often been abun-
dant enough on the red-osier dogwood (Cornus sanguinea) to be
decidedly injurious. Like the other small twig-girdlers, this species
can best be destroyed by cutting off and destroying the affected

Fig. 52. Dogwood Twig- Fig. 53. Cornus leaf injured by
girdler, Oberea_ tripunctata, feeding of adult Dogwood Twig-
pupa. About 2% times girdler, Oberea tripunctata.

natural size.

branches ata time when they are certain to contain the borer; that
is to say, in this case, in any month except June and July. _

The various species of this genus have been so imperfectly dis-
tinguished that a specific description of this will not be attempted
here; but the reader is referred to the illustrations for its general
characters. Its larva is much subject to destruction by parasites ;
and a characteristic parasitic species has been repeatedly bred by
us from infested twigs.

48

Tue Locust Borer
(Cyllene robinie Forst.)

A great obstacle to the growth of the common black locust as
a timber tree in Illinois has been the work of a borer which in-
fests this tree only, multiplying year after year in a locust grove
until it destroys every tree. It was a common practice in the early
settlement of the northern part of the state for the farmers to plant
a grove of locusts, with a view especially to a supply of fence-posts.
These groves were, however, all destroyed by this borer during the
middle part of the nineteenth century, and the planting of this
tree was universally abandoned at that time. Of course, with the
disappearance of the tree the borer likewise disappeared, and the
growing of the locust is now again possible if due precautions be
taken against its destruction by this insect. Fortunately, the recent
work of Dr. A. D. Hopkins, in charge of forest insect investigations
for the United States Department of Agriculture, has made it per-
fectly feasible to grow locusts with little or no loss from this cause,
and the following account is mainly taken from his publications on
this subject.

The first evidence of attack by this borer in spring is a fine
brownish dust and an oozing of sap from the bark. Later, gumlike
exudations appear on the injured spots, and quantities of yellowish

Fig. 54. Locust Borer, Cyllene robiniw, pupa: a, front view;
b, back view. Enlarged as indicated. (U.S. Dept. of Agri-
culture.)

|

—_— iF

49

~ dust lodge in the forks of the tree or branches, and in the loose bark

-

on the trunk and around its base. Badly infested trees show a
dwarfed, faded, or sickly foliage about the middle of May, and
many of the leaf buds fail to open. The author of this injury is
a whitish, thick-bodied, distinctly segmented, seemingly footless
grub, nearly an inch long when full grown, with small head, and only
a pair of minute feet on the next segment behind. It hatches from
eggs laid in crevices of the bark from August to October. The
young borers are still very small when the winter overtakes them,
and they hibernate in small cavities made by them in the outer bark
of the trunk and branches. They commence operations when the sap
of the tree begins to flow the following spring, and presently pene-
trate the wood, burrowing actively about until July or August, in
central Illinois, when they begin to change to the pupa (Fig. 54),
to emerge about a month later in the beetle stage (Fig. 55).

Fig. 55. Locust Borer, Cyllene_robinie: a, male; 6, female. Enlarged as
indicated. (U.S. Dept. of Agriculture.)

The adult is a very showy, elongate, brown beetle, five-eighths to
three-fourths of an inch in length, conspicuously marked with three
straight bands of bright yellow across the thorax and five broken or
irregular bands of the same color across the wing-covers. There is
also a bright yellow patch on the upper side of the tip of the ab-
domen. The beetles are to be found in September, and occasionally
in early October, on locust-trees, and on various species of golden-
rod, upon the flowers of which they feed. Now and then a speci-

50

men may survive the winter and be taken abroad in April, or even
in May.

From the foregoing statement’ it is evident that the time of cut-
ting trees, whether to thin the grove or for commercial use, is an
important item in the control of this beetle. All such cutting should
be done between October 1 and April 1, care being taken that all »
trees showing the presence of the borer are selected for removal.
The bark should then be taken off, and the brush and rubbish should
be burned. Simply to kill the larvee and borers in badly infested
and damaged trees, these should be cut and destroyed in May and
June, when their condition can be readily detected; but the work
should be completed by the time the flowers have all fallen from
the trees, as otherwise the borers may mature and escape. Where
the beetles are abundant on the goldenrod, they may be attracted and
killed, according to Dr. A. D. Hopkins, by smearing molasses
poisoned with arsenic upon the trees, due account being taken of
the fact that honey-bees are liable to destruction by this poison, and
that it should not be used where these are kept. Unsuccessful ex-
periments were made by one of my assistants, Mr. W. P. Flint, in
Ig10, with a mixture of sugar and vinegar, and another of sugar
and alcohol. Altho attractive to a variety of other insects, the
beetles of the locust-borer paid no attention to them. Tanglefoot;
on the other hand, placed on the trees September 16, when the
beetles were freely running about mating and laying their eggs,
disabled the beetles and put a stop to their operations.

Highly useful directions for the management of locust plan-
tations in a way to prevent injury by borers, are contained in Bulle-
tin 58 of the Bureau of Entomology of the U. S. Department of
Agriculture, printed in 1910.

THE Oak TWIG-PRUNER
(Elaphidion villosum Fabr. )

Among the more striking and curious kinds of insect injury to
trees are those which take the form of amputation of twigs and’
small branches during the growing season—an injury which seems
purposeless and excessive until one sees. just how it benefits the
author of it.

The oak twig-pruner (Fig. 56) is one of the best known Ameri-
can insects with this habit of injury, affecting, as it does, a large
variety of trees and shrubs, and injuring most frequently some of
the commonest and most useful species. It is best known, perhaps,
for its work on oaks, hickories, and maples, altho it has been re-
ported to attack also apple, peach, pear, plum, quince, locust, redbud,
sumach, Osage orange, fir, grape, and climbing bittersweet. In IIli-
nois we have bred it from oaks, hickories, persimmon, and peach,

51

and have found it thruout the state. In parts of Michigan, peach-
trees have sometimes been nearly destroyed by it, and an equally se-
rious injury has been done by it in New York to pears. In Illinois
we once found it at Effingham cutting off young apples-trees from

Fig. 56. Oak Twig-pruner, Hlaphidion villosum, larva.
About 5times natural size,

one to two feet above the ground; and Dr. F. W. Goding reported
it, in 1884, as doing great damage to hickory and elm at Ancona, in
Livingston county. In Pennsylvania, oak forests have been so in-
fested by it that carloads of the twigs might have been collected
from under the trees; and in Connecticut, hickories have been so
thoroly pruned that a barrel of twigs and branches have fallen
from a single tree.

The injury done by this insect is not, however, so severe as it
looks. It may affect considerably the appearance of young trees,
by deforming their top; but large trees are generally little harmed
by the pruning they receive, and the littering of lawns with ampu-
tated twigs is at most an annoyance merely. The girdled twigs and
branches may vary in length from a few inches to several feet, but
Dr. Fitch mentions one that was ten feet long and over an inch
thick. Commonly, however, they are a quarter of an inch or less
in diameter, and vary from two to six inches in length. Occasion-
ally a single one will contain two larve, the burrows then running
down each side of the twig. Fallen limbs, if not disposed of, may
serve, as Chittenden has said, as breeding places for various kinds
of injurious borers, which may come out from them to attack and
injure living trees.

The method of the pruner’s work is such that a fallen twig is
seen to have been hollowed out centrally—a large part of its interior
often being eaten away—and plugged with sawdust, and its larger
end has been gnawed off from within, having a cut surface as smooth
as if made by a chisel.

The adult twig-pruner is a rather slender, dark brown beetle
(Fig. 57) from a half to three-quarters of an inch in length,
sparsely covered with coarse white or yellowish hairs which show
a tendency to collect in irregular clumps or spots. The edge of the
tip of each wing-cover is concave between two stout sharp spines
or teeth, of which the outer is usually the larger. The female lays

52

her eggs in the smaller twigs of living trees, most commonly in
July. The young larva first eats out the wood under the bark in
the direction of the grain, packing its burrow behind it with its
castings, and working towards the base of the twig. Later it cuts
holes in the bark thru which these castings are rejected, and
then follows the center of the twig, making a channel more or less
oval in cross-section, corresponding to its own shape. When it has
reached its growth it begins to gnaw, from within, a circular groove,
deepening this until the twig or branch is so weakened at this

Fig. 57. Oak Twig-pruner, Hlaphidion villosum,
adult. About5 times natural size.

point that the wind readily breaks it off, usually carrying the insect
with it. Occasionally, however, the larva is left in its burrow on
the tree and finishes its transformations there. The value of
this operation to the pruner would seem to be a preparation for
the exit of the beetle, which originates within the burrow, but
which has not jaws of a sufficient strength to enable it to gnaw
its way out thru the wood inclosing it. This explanation, given
by Chittenden, seems at least to be the most reasonable among
several that have been proposed to account for this curious hai
After the twig has been cut off the larva within it plugs up the
severed end, changes to the pupa, and later to the beetle, coming out
as an adult the following summer.

53

Published accounts disagree as to the length of the life cycle of
this species. It seems to be a single year under the most favorable
conditions, but capable of being lengthened to two or even three
years, particularly if the branch dies before the larva is full grown.

As nearly all the borers pass the winter in the fallen twigs, it
easily follows that their injuries may be readily arrested by gather-
ing these up and burning them in winter or in spring. This effec-
tive measure is so simple and so easily applied that no other seems
necessary.

THE BRoNzE BIRCH-BORER
(Agrilus anxius Gory)

This insect is a deadly pest of the birches, especially of the beau-
tiful and popular white birch, which it is quite capable of extermin-
ating locally if its presence is not early detected and if prompt meas-
ures are not then taken for its destruction. As an infested tree is not
likely to last more than two or three years, the necessity of energetic
measures is obvious. Unfortunately, this insect does not usually
make conspicuous local marks of the injury it is doing, and the
earliest sign of its presence is often the death of one or more
branches in the top of the tree. Ifa birch is seen to be dying at the
top it should at once be examined for evidences of the presence of
this borer, since in some cases this condition may be due to drought
or other general causes. If the bronze borer be the cause, the fact
may be ascertained by lifting the bark from dead branches. which
are not yet dry, or from the more unhealthy looking spots on the
living parts of the tree. If the insect be present, its tortuous or
zigzag burrows will be noticed, and further search will disclose the
borer itself in one or more of its stages of larva, pupa, or adult.
Sometimes, indeed, its presence is shown by a ridged appearance of
the bark, the ridges running crosswise of the branches or in a more
or less spiral direction. Peculiar rusty or reddish spots may also be
seen on the larger branches or on the trunk where the bark has been
undermined by the interlacing burrows of the borer. Often branches
weakened by the borers and by consequent decay of the wood, break
at the point of injury, either hanging down or falling from the
tree. This appearance is rather characteristic of the work of the
borers, and may serve to distinguish an infested tree from a “stag
head,” due to drouth.

In its destructive stage this insect is a small, flattened, footless,
creamy white grub about three-fourths of an inch long when full
grown, with dark mouth-parts and a small head which is partly
drawn back into the broad, flat, pale brownish, first segment of the
body. At the opposite end is a pair of minute forceps-like spines,
brown and hornlike, with two teeth on the inner edge of each. In

this larval condition the borer may be found in its burrows beneath

d4 |

the bark at any time during fall, winter, and early spring. If the
tree has been long infested, the bark is usually perforated by small
roughly semicircular holes about twice the diameter of the head of
an ordinary pin. (Fig. 58.) These holes are made by the beetles
When they come out in May and June for their brief life in the
open air.
The beetle (Fig. 59) is a hard, small, bronze-green or violet in-
sect, varying somewhat in size, but approximately half an inch long
or a little less. It is shining but minutely punctured under a glass,

Se.

je
=
4
=

Fig. 58. Exit holes of the Bronze Birch-borer, Agrilus
anxius, inthe bark. Naturalsize. (Cornell Experiment
Station.)

Fig.59. Bronze Birch-borer, Agrilus
anxius, adult. About 5 times natural
size.

with the sides nearly parallel, tapering conspicuously behind to a
blunt tip, notched where the rounded ends of the wing-covers come
together.

Altho most notorious for its injury to the white birch, es-
pecially the cut-leaved variety, it infests all the birches. It is the
most destructive enemy of these trees in the Chicago parks, thru
which it is generally distributed. It is especially dangerous because
there is no means of destroying it which does not involve also the
destruction of the infested tree. It is a saddening conclusion which
is forced upon the owner of a beautiful birch infested by this borer,
that the tree is doomed, and that the only means of saving other
trees in its neighborhood i is to cut it close to the ground in winter or
spring, as early as the first of May, and to burn it, trunk and
branches, before the beetles can emerge to lay their eggs elsewhere.

55

The larve hatch in June, and possibly also in July, from eggs
laid in crevices in the rougher places of the bark. They bore
thru the bark at once and begin to mine in the sapwood, some-
times dipping inward to the older wood or even penetrating to the
‘center of a small branch. The irregular mine is always packed with
the castings of the grub, and increases in diameter, of course, as
the latter grows, measuring at the largest about an eighth of an inch
across. Here tlie borer lives in the larval state until the latter part
of the following April or early May, when it begins to transform
within its burrow to the pupa stage, and within another month to
the beetle. This escapes from the tree from the middle to the last
of June in northern Illinois, by gnawing through the bark, flies
abroad to feed on the leaves of trees, and soon pairs and lays its
eggs. Curiously, it seems to feed but little on the birch, preferring
the leaves of poplar, willow, and elm to those of its native tree.
There is, indeed, some evidence that it infests the willow, producing
gall-like swellings on the twigs, but the identity gf the species to
which this injury is referred is not positively settled

Trees of large size are often killed by this borer within three or
four years after they first become infested, and few live.more than
two or three years after the top branches begin to die. The neces-
sity of prompt action is thus manifest, and as the time of the escape >
of the beetles varies with latitude and the weather of the year, it is
best to take time by the forelock and to destroy the infested tree
as early at least as April 1. Then one may be sure that nothing can
have escaped from it to extend the injury.

This insect is not now known to range beyond Virginia to the
south or Illinois to the west, but it very likely occurs wherever
birches are grown. We have lately found it (1910) outside Chi-
cago, in Elgin, Rock Island, Moline, and Bloomington, abundant
enough in all these places to be decidedly injurious to the birches.
It has been quite fully discussed by Professor M. V. Slingerland in
Bulletin 234 of the Cornell University Agricultural Experiment
Station, published in January, 1906, and briefer accounts may be
found in the report of Dr. E. P. Felt, State Entomologist of New
York, in “Insects Affecting Park and Woodland Trees” (page
284), published in 1905; in an article by F. H. Chittenden published
in 1898 in Bulletin 18, new series, of the Division of Entomology,
U. S. Department of Agriculture; and in a paper on “A Disease
of the White Birch,’ by John Larsen, printed by the Michigan
Academy of Science in its third report (1902).

THE SCURFY SCALE
(Chionaspis furfura Fitch)

The so-called scurfy scale is the commonest of all scale insects
thruout the state on shade and orchard trees. The female scale

56

(Fig. 60, a, c) is about a tenth of an inch in length, irregularly
oval, with a yellowish point at one end, and but very slightly con-
vex. It is nearly white when fresh, but becomes gray or sooty
with exposure. The scale of the male insect (Fig. 60, b, d) is

Fig. 60. Scurfy Scale, Chionaspis furfura:
a,b, female and male scales, natural size; ¢,
d, same, enlarged.

narfow, with sub-parallel sides, and is marked by three longitudinal
ridges. The species may be readily recognized in winter by the
fact that under each female scale will be found a small mass of
minute, purplish eggs. The young appear to the naked eye as
active, snowy whitish or reddish specks. These insects are often
so abundant on an infested tree as to give a scurfy appearance to
the trunk and limbs.

This scale insect is a general feeder, but is especially common
on rosaceous plants. It also heavily infests the elm, which seems the
most susceptible to its injuries of any of our ordinary shade trees.
The red-twigged dogwood is often incrusted by it, and the moun-
tain ash, hawthorn, pear, and currant are sometimes attacked. The
scurfy scale winters in the egg, and hatches, with us, during the
latter half of May—earlier or later according to the season and the
part of the state. In central and southern Illinois eggs are laid
for a second generation, the date of which, however, has not been
accurately determined. Altho this can not be classed among the
more destructive scale insects, it is nevertheless injurious where es-
pecially abundant, checking the growth and diminishing the vitality
of the infested tree or shrub in a way to make it less presentable and
more susceptible to the attacks of other insects and of disease.

Two insecticide sprays are fairly effective against this insect;
one a winter spray of lime and sulphur, prepared and administered
as described in detail under the article concerning the San Jose
scale, and the other a summer spray of kerosene emulsion, a formula

a7

for the preparation of which is given under the cottony maple scale.
The lime-sulphur mixture should be applied as late in the winter as
practicable, best just before the opening of the leaves in spring. The
kerosene emulsion must be applied immediately after the hatching
process is virtually complete, a point which can only be determined
accurately by careful observation. If the young are allowed to live
too long they become covered and protected, after fixing themselves,
by a waxy scale which the emulsion will not penetrate. It should be
applied in a strength to contain ten percent of kerosene. Dr.
James Fletcher, Dominion Entomologist, Canada, recommended
spraying infested trees with a whitewash made by slaking a pound
of lime to the gallon of water, one such application to be made in
fall as soon as the leaves have fallen, and a second immediately after
the first has dried. This is said to loosen the hibernating scales,
which subsequently fall from the tree with the dried whitewash.

THE OYSTER-SHELL SCALE
(Lepidosaphes ulnu Linn.)

The oyster-shell scale is among the more conspicuous and easily
recognized of the smaller scale insects of our trees and shrubs, the

Fig. 61. Oyster-shell Scale, Lepidosaphes ulmi: a, female scale,
under side, showing insect and its eggs within; 0,same, from
above; c, same, natural size; qd, e, male scale, enlarged and
natural size.

38

common name suggesting its most conspicuous character. It has,
indeed, the convex, elongate, and more or less bent and irregular
form of an oyster shell. The female scales (Fig. 61, a, b, c) are
about an eighth of an inch long, the male scales (Fig. 61, d, e)
smaller, with a little hinge or flap behind, thru which the winged
males escape when mature. The scale is usually brown to dark
brown in color, tho occasionally bleached to gray by exposure
to the winter weather. The eggs of the species hatch in Illinois
shortly after the time the apple blossoms fall. Each female scale
has during the winter from fifty to a hundred and twenty-five pale
yellowish eggs beneath it, from which the young emerge during
the latter part of May or the first of June. A second generation
occurs in central and southern Illinois early in July. The young
are able, at first, to crawl about somewhat actively, and it is
principally by this means that the species is distributed, altho it
may be conveyed to distant points upon infested nursery stock,
The scale insect is both larger and more injurious than the scurfy
scale, and infests also a larger variety of trees and shrubs. Elm,
poplar, willow, horse-chestnut, lilac, red-twigged dogwood, and
currant are among those most frequently and seriously injured.

The treatment for this scale is identical with that described in
the article for the scurfy scale, just preceding.

THE SAN JOSE SCALE
( Aspidiotus perniciosus Comst. )

This notorious and destructive pest is much less injurious to
ornamental vegetation than to fruit trees and shrubs, but is never-
theless decidedly harmful to several of the former, particularly to
those belonging to the family of roses. It is also very injurious to
the mountain ash, but the Japanese quince (Pyrus japonica) is the
common shrub most likely to betray its presence.

It is a circular, grayish or yellowish, scale insect about one-
sixteenth of an inch in diameter, but slightly convex, and marked
by a central nipple and one or two surrounding circular ridges. It
is an inconspicuous object, but is recognizable by the appearance
which it gives to a badly infested bark (Fig. 62), which it covers
with dark gray patches of a continuous grayish crust, which exudes,
when crushed with the finger-nail, an oily, yellowish substance due
to the pressure on the living insects under the scales. The bark of
a tree but sparsely infested may be seen, on close examination, to
be irregularly specked with small circular granules which give it an
unhealthy look. The surface immediately beneath the living scales
often shows a reddish discoloration; and on the leaves and green
twigs are more conspicuous red blotches which surround the scales.

3 59

The largest scales are about the size of the head of an ordinary
pin, and the smallest ones are mere specks on the twig.

This insect passes the winter partly grown, reaches its full size
in spring, and begins to bring forth its living young about the first
of June, in average years, in the central part of Illinois. These may
be seen as minute yellow specks wandering over the surface in search
of a suitable place to establish themselves. This period of active
life is often limited to a few hours, and at most to one or two days.
Three or four generations are bred 10 a single season,

Fig. 62. San Jose Scale, Aspidiotus
perniciosus. Natural size. (Connec-
ticut Experiment Station.)

It has been found commonly infesting and often injuring more
than seventy trees and shrubs, and occasionally nearly as many
more. The commoner kinds coming under the former list are some
of the dogwoods, the hawthorns (Crategus), the quinces, the pop-
lars, the cherries and pears, currants and gooseberries, roses, willows,
mountain ash, snowberry, lilac, basswood, Osage orange, and the
elms. Those less seriously infested are the maples, horse-chestnut,
Virginia creeper, the birches, chestnut, catalpa, hackberry, the flow-
ering and other dogwoods, the persimmon, Forsythia, white ash,

60

honey-locust, Althea, pecan, black walnut, mountain laurel, honey-
suckle, mulberry, white spruce, sour cherry, sumach, smoke-bush,
locust, raspberry and the blackberry, elder, sassafras, various species
of Spirea, arbor-vite, Viburnum, and grape. Popular species not in-
fested by it are Atlanthus or tree of heaven, papaw, spice-bush, bar-
berry, trumpet-vine, the hornbeams, cedar, bittersweet, buttonbush,
Judas-tree, fringe-tree, pepperbush, leatherwood, gingko, Kentucky
coffee-tree, witch-hazel, English ivy, hickories except the pecan,
hydrangeas, yellow jasmine, “butternut, juniper, larches, sweet gum,
tulip-tree, matrimony-vine, wax myrtle, black gum, syringa, pine,
sycamore, the oaks, the rhododendrons, bald cypress, trumpet-
creeper, blueberry, hemlock, /Vistaria, and prickly ash. The last
list is especially important in [linois, thruout which the San Jose
scale is certain ultimately to become generally distributed, because
it includes a large and varied list of ornamentals from which selec-
tions may be made without the risk of loss or injury by this most
destructive pest.

The San Jose scale is conveyed to distant points mainly by
the trade in nursery stock, and otherwise it spreads only by means
of the minute crawling young. Its means of dispersal are so slight
that it tends to concentrate upon any tree infested until the latter
becomes completely covered by it, a fact which, taken together with
its numerous generations, its rapid rate of multiplication, and its
freedom from parasites capable of overcoming it, make it the dan-
gerous enemy which it has become.

The San Jose scale can be destroyed by the winter use of one of
the lime and sulphur mixtures, which may either be purchased ready-
made in condition for use by dilution only, or may be brought into
solution by boiling the raw materials together according to the fol-
lowing directions.

Materials: 15 pounds of lime, 15 pounds of sulphur, and 50 gallons of
fairly soft water. For 50 gallons of the spray, heat 12 gallons of water in a
4o-gallon iron kettle, mixing, in the meantime, in a separate vessel, 15 pounds
of sulphur with enough water to form a thin paste. Add this sulphur to the
water in the kettle and bring the mixture to a temperature just below boiling.
Then add 15 pounds of best lump lime, keeping cold water at hand to use as
the mixture threatens to boil over. After the lime is fully slaked, boil for
40 minutes, with almost constant stirring. Then strain into a 50-gallon spray-
tank and fill with water, which had better be warm, although cold water will
do. To prepare 100 gallons of the spray at a time, heat 20 gallons of water
in the 4o-gallon kettle, add 30 pounds of sulphur—previously reduced to a thin
paste with water—and to this put 30 pounds of lime. Boil as before, and
dilute to 100 gallons. c : ; ; :

If a supply of steam is available for cooking the mixture, this will be
found a much more convenient source of heat. The cooking is then done in
barrels or other vessels, from which the fluid is strained into the spray-tank.
The disturbance caused by the introduction of steam makes stirring unneces-
sary. When cooked with steam the mixture does not ordinarily become so
dark as when boiled over a fire, but the insecticide effect is nevertheless the
same.

61

PUTNAM’S SCALE
(Aspidiotus ancylus Putnam)

This is a circular or oval, dark gray or black, scale insect, about
one-twelfth of an inch in diameter, with a brick-red point at one side
of the center. It closely resembles the San Jose scale in general
appearance, but does not present the conspicuous ring and nipple
structure of the latter, altho the young have usually a nipple and
a rather indefinite ring.

It passes the winter but partly grown, but differs from the San
Jose scale in the fact that it reproduces by means of eggs laid in
late spring or early summer. ‘There is but one generation in a
season.

It has been found on elm, willow, oak, hemlock, mountain ash,
Tlex, white birch, Prunus, ash, beech, hackberry, linden, maple,
Osage orange, and water-locust. It is rarely injurious enough to
require special attention.

THE WALNUT OR WILLOW SCALE
(Aspidiotus juglans-regie Comst. )

This species, altho common on a number of shrubs and shade
trees, is of little importance except on the willow, to which it is a
veritable pest. It is easily distinguished from other scales of the San
Jose relationship by its relatively large size, its diameter being 3
mm., or an eighth of an inch. The female scale (Fig. 63, a, e,) is

Fig. 63. Walnut Scale, Aspidiotus juglans-regie: a,b, female and male scales,
enlarged; ¢c, male pupa; d, e, male and female scales, natural size.

circular, flat, with a prominent pink or reddish point at one side
of the center. ‘The male scale (Fig. 63, b, d) is elongated, with a
corresponding point near one end. The female passes the winter
as an adult, and lays her eggs in early spring.

Treatment the same as that for the scurfy scale.

62

THe Cotrony MAPLE SCALE
(Pulvinaria vitis Linn.)

The cottony maple scale (Fig. 64) is one of the best known
scale insects because it heavily infests several very common shade
trees, and because the cottony masses beneath the body of the adult
female in early summer make it a very conspicuous object. These
large white masses are a deposit of waxy threads within which are
the minute, oval, pale yellowish eggs.

The history of this insect in Illinois since 1867 exhibits suc-
cessive periods of abundance and of scarcity, each averaging about
four or five years for the state as a whole. That is, thruout
some considerable part of the state, and often over most of it,
the maple scale has been injuriously abundant once in eight or ten
years, and its period of abundance has lasted, as a rule, about half
this time. In any given locality, however, it has usually been in-
jurious for a much shorter time, often for not more than one or two
years. The cessation of its injuries and its virtual disappearance
from the trees infested by it have seemingly been due almost wholly
to the agency of its insect enemies.

The soft maple (Acer saccharinum) is the tree most generally
and heavily infested by this insect. The hard maples, on the other
hand, are infested but slightly if at all. The box-elder is also greatly
subject to injury, and next to this, perhaps, the linden or basswood.
Among the other trees and woody plants often more or less injured,
are the elm, honey-locust, black locust, black walnut, sumac, willow,
poplar, beech, hawthorn, bittersweet, grape-vine, and Virginia creep-
er. We have found mature egg-laying females on the horse-chest-
nut, honeysuckle, dogwood, trumpet-creeper, mulberry, snowberry,
smoke-tree, Spirea, false syringa (Philadelphus), and |W istaria.
Oak, ash, and catalpa are not infested in northern Illinois, but injury
to oaks is reported from Georgia. The pear is said to be most liable
to injury among the fruit trees, and apple, plum, and peach are
sometimes infested. Serious damage to fruit trees is, however, very
unlikely. The migrating young, which are often washed from trees
by rain, or blown off in considerable numbers, may maintain them-
selves for a time on a great variety of woody and herbaceous plants,
those on the latter, of course, perishing with the advent of frosts.

In early summer this scale, when very abundant, coats the under
side of heavily infested limbs with a thick layer of cotton-like waxy
masses, each projecting from beneath a brown cap or scale—the
flat body of the mature female. . This “cotton” is secreted and the
eggs are deposited within it in late May or early June in the latitude
of central Illinois, but usually one or two weeks later in the Chicago
district. |

Something over 3,000 eggs are usually laid by each female, the
number ranging, in our counts, from 2,856 to 3,863, with an average

Fig. 64. A Soft maple twig badly infested with adults of the Cottony Maple Scale,
Pulvinaria vitis. About natural size.

64

of 3,410. In central Illinois the eggs ordinarily hatch in June, and
in the northeastern part of the state in early July, or later if the
weather of the time is unfavorable. Virtually all are hatched, as
a rule, by the end of July.

When first hatched the six-legged young (Fig. 65, a, e, f) move
slowly about as creeping yellowish specks about twice as long as
wide. They soon settle upon the leaves, mostly upon the under side

Fig. 65. Cottony Maple Scale, Pulvinaria vitis, immature stages: a, newly
hatched young, under side; 06, c, young female, top and side views; d,
young male; e,/, young on leaf and leat stem, Natural size shown in a.

along the veins, but a considerable percentage also on the upper
surface. Soon after settling down, a thin waxy layer forms on the
back, and in about three weeks the insect has virtually doubled in
size. As they increase in size the male and female scales become
distinguishable (Fig. 65, b, c, d) by the fact that the former are
comparatively narrow and more convex. From these the winged
males (Fig. 66, a, b, c) emerge to fertilize the stationary females
in August and September, perishing soon thereafter. In autumn
the young females migrate from the leaves, which are about to fall,
to the twigs, upon which they pass the winter and, indeed, the re-
mainder of their lives. In spring the female scale (Fig. 67) is ellip-
tical, convex on the back, with a low, rounded, median ridge. It is
pale greenish or whitish yellow, marked with black or dark brown.
When full grown, about the middle of May, it is 4 to 6 mm. long
and 3 to 4.5 mm. wide. Its body is at first closely applied to the sur-
face of the twig, but with the development of the eggs beneath it the
abdomen is gradually raised from the bark to an angle of forty-five
degrees or more.

It is usually difficult to say whether trees infested by this insect
should receive special treatment, or whether they may be safely left

Oo
Or

to the natural course of events. The cottony maple scale is ex-
tremely subject to parasites and attacks of other insect enemies,
particularly to the black hemispherical ladybugs and their larve, the
latter of which feed upon the egg masses in spring and summer.
With an extraordinary abundance of the scale insects themselves

Fig. 66. Male of Cottony Maple Scale, Pulvinaria vitis: a,adult;
6, c. antenna and leg enlarged; d, e, second stage of pupa and its
cast skin; /,g, true pupa and its castskin. All greatly enlarged.

these insect enemies improve the opportunity for unusual multiplica-
tion in a way to produce a greater number than can possibly be
maintained permanently by the scale insects. A check is thus put
upon the increase of the latter which, within a few months, may re-
duce them to insignificance. The consequence is an irregular peri-

odicity in the numbers of the cottony maple scale such that two years
of injurious abundance rarely succeed each other in the same place.
Nevertheless, where trees are evidently suffering from the scale at-
tack it is always prudent, and often necessary, to take artificial
measures of protection.

66

As the newly hatched young are especially susceptible to the
petroleum insecticides, which act by contact, a definite knowledge of
the hatching period has an important practical value. In central
Illinois this period extends approximately from June 15 to July 20.
In and about Chicago it commonly begins about two weeks later, and,
continues for a period of three weeks, this retardation being appar-
ently due to the higher latitude and to the neighborhood of Lake
Michigan. The period varies, in short, as to its beginning time, with
the advancement of the season, and once begun, the rapidity of the
hatching will depend, other things being equal, on the warmth of the
weather. It is also influenced locally by the amount of foliage on
the trees, the eggs hatching later and more slowly in a dense tree-
top than in one more open to the sun.

The only insecticides available against these insects are those
which kill by contact, and of these the kerosene mixtures have thus
far been found the most useful. Even these can be applied only to
the young scales shortly after they hatch from the egg, no insecti-
cide treatment being available for the destruction of the large and
conspicuous females upon the twigs in May and June. The common
kerosene emulsion, made by thoroly and intimately mixing kero-
sene with one-third of its volume of a strong soapsuds, is a satis-
factory spray when diluted to contain ten percent of kerosene for
summer use, and sixteen to eighteen percent is used in winter. As
a summer spray this emulsion must be used twice in succession, once
when about half the eggs are hatched and again about ten days there-
after. A single treatment in winter is about the equivalent in prac-
tical effect of two such summer sprays. Large trees in a sandy soil,
and especially those in more or less unthrifty condition, should be
guarded against possible injury to the roots from the dripping of the
kerosene spray, or from that part of it which may run down the
trunk and so reach the earth. For this purpose it would be well to
cover the ground before spraying with a thin layer of straw, packed
closely around the base of the trunk, and later to. gather this up and

carry it away.

The cost of materials for large trees will average approximately
fifteen cents a gallon for the summer spray, and about twice as much
for the winter strength.

Kerosene emulsion is made as follows: Dissolve one pound
of common soap, or half a pound of whale-oil soap, in one gallon of
water by boiling, remove from the fire, and add two gallons of kero-
sene. Then with a spray pump force the mixture back into itself for
about five minutes, or until it presents the appearance of a thick
cream and no longer separates on standing. ‘This is the undiluted
emulsion. For a mixture containing ten percent of kerosene, add
seventeen gallons of water to the three gallons thus prepared. For

a

67

an eighteen-percent kerosene emulsion, add eight gallons of water
to the stock emulsion. Soft water is to be preferred. _

The following tables will show the effects of kerosene sprays
as applied by us in 1905 and 1906.

SUMMER SPRAY

Treatment
No. of | heaves | Scales | Percent
Part of trees ex- ex- killed
Insecticide hatching amined | amined |by spray
period
10) percent kerosene....... Beginning 1 75 48,789 33
10 percent kerosene .. ...| Middle 1 50 19,425 64
10 percent kerosene.... ..| End 3 150 281,271 68
10 percent kerosene....... Middle
and end 1 100 57,179 82
WINTER SPRAY
Percent
Date of | Scales | Percent
py eu suaayes Beat counting] counted| killed
December 26 to January 5
(Gia) Boa pne ae an a ee oor eae aes 19 Feb. 1 12,703 86
Fantiary: 11to 13 (ounce)... :...- »'« rouseerore 20 Feb. 1-2| 23,061 91
January 11 to 13 and March 30
Atay Se) aot ceeietelintal <tekai aravelar <(«larster soa) wieie 19-24 June 10) 48,395 91

MISCELLANEOUS ECONOMIC INSECTS

By CHARLES A. HART

THE Heart-woop Borer
(Parandra brunnea Fabr. )

Parandra brunnea is a shiny chestnut-brown, parallel-sided
beetle (Fig. 2, 3) about five-eighths of an inch to three-quarters
of an inch long and a quarter of an inch or less in width. It be-
longs to a small family (Spondylid@) closely related to the long-
horn borers (Cerambycid@) and of similar habits. The larva is
a wood borer about an inch long (Fig. 4), resembling the common
round-headed borers except in the strong forward slope of the
thorax and the small low-set head.

A variety of observations made by the writer during a number
of years seems to indicate that the heart-wood borer, altho gen-
erally supposed to feed only on dead wood, is a much more im-
portant and destructive pest of fruit and shade trees than the scanty
references to it in economic literature would indicate, and the pub-
lished and observed facts about the species are therefore here
brought together.

PUBLISHED DATA

In the American Entomologist for January, 1880, Dr. C. V.
Riley acknowledged, from Shelby Reed, of Scottsville, N. Y., sam-
ples of a borer said to affect badly the roots of black ash trees in
New York to such an extent that it was killing out these trees in
parts of the state. The larva sent was new to Dr. Riley, and he
asked for more specimens. In the number for August of the same
year, a second letter from this correspondent is published, accom-
panied by more material illustrating the injury, including the adult,
which was identified by Riley as Parandra brunnea. Riley answers
that its larve are frequently found in dead or decaying wood of
various trees, especially oak and beech, but are not known to attack
healthy timber ; and that from the evidence at hand the decay of
the ash trees was apparently not primarily caused by the borer. He
added, however, that there could be no doubt that the death of the
trees was accelerated by the working of these larve, and that the
species might therefore be considered injurious, especially when it
occurred in such numbers as in the present case.

The observations of Mr. Reed, as detailed in his letter, agree
closely with our observations, and are worth repeating. He says

69

that the tree breaks by wind pressure where most bored, usually
near the ground, sometimes ten or twenty feet up; that the decay
begins at the center and progresses outwardly; that, avoiding the
outward shell and the inward mush, the larve feed where decay is
incipient; that, as one of the sections plainly shows, if they venture
too near the surface they fall-a prey to the woodpeckers; that away
from browsing live stock young ash seedlings remain healthy and
plentiful; that this insect is most numerous in trees of full, mature

Fig.1. Heart-wood Borer, Parandra brunnea, work of larva in base of soft maple in
Urbana, weakening the base so that the tree fell during a high wind,

growth; and that exposure of the trunk to the sun hastens the in-
crease of the insect.

Packard, in the Fifth Report of the United States Entomologi-
cal Commission, says on the authority of Mr. Chittenden that the
species has been taken under the bark of oak trees and is very com-
mon under the bark of cultivated cherry trees. Lugger says that in
Minnesota it is very common under the bark of pine; and Gibson
quotes Townsend as saying that it is found under basswood bark,
and that it infests a variety of deciduous and coniferous trees.

Quite recently, Snyder* has reported this species as seriousty
injurious to chestnut telephone and telegraph poles, shortening their

#Bull. 94, Pt. 1, Bureau of Ent., U. S. Dept. Agr.

70

period of usefulness by burrowing into them not far above or
below the surface of the ground; and Gahan* has added further
details on the same injury.

The species has a wide distribution, ranging from the Atlantic
coast westward to Arizona and southern California, and northward
to Ontario, Canada.

DATA FROM OFFICE RECORDS

An apple tree on my place was blown down December 9, 1899,
and its base was found honeycombed by larve. Infested portions
were placed in a breeding cage, and beetles of Parandra brunnea
emerged July 17, 19, and 21, and August 7.

When on the grounds of a large [linois nursery near Springfield,
August 27, 1904, my attention was called to large apple orchards
which were being seriously injured by borers, supposed to be the

Fig. 2. Heart-wood Borer, Par-

andra brunnea, male at right, fe- - ae a a
maleatleft. Very slightly

enlarged. (U.S. Dept. of Agricul- Fig.3. Heart-wood Borer, Parandra brunnea,
ture.) male adult.

common round-headed borer (Saperda candida). It was reported
that the infestation had been evident since June, and that altho
there were few pupz in the wood at the time, they had been very
common earlier in the season, up to about three weeks before. This
agrees closely with the breeding of adults just mentioned. It was
said that nearly all the old trees had been heavily infested, and
several larve were found even in young nursery stock. The owner
and his foreman agreed that the larvee attacked healthy wood and
even healthy trees, so that much damage was shown.
* Jour. Econ. Ent., Vol. IV, p. 299. ’

71

An examination of the trees showed numerous larve, with
remnants of adults of Parandra brunnea. The attack seems to
begin at the base, less commonly higher up on the trunk, and prob-
ably at some point of injury and decay. The larvee then work up-
wards, especially about the central axis, into living heart-wood,
which they riddle and cause to decay until the base is a mere shell.
The riddled space is usually roughly conical in form,

A large soft maple tree about two feet in diameter on a street
near the University of Illinois, had some large roots cut away close
to its base to make room for a sidewalk. The exposed surface de-
cayed, of course, and some years later, in August, 1907, the tree
blew down. It was examined August 5 by Mr. J. D. Hood, who
found the entire base honeycombed with burrows, this honeycombed

it
Cc
Fig. 4, Heart-wood Borer, Dig. 5.) Heart-
Parandra brunnea: a, larva, wood Borer, Par-
enlarged as indicated; 0, andra brunnea,
side view of its head and pupa. Knlarged
fore part; ¢, clypeus and as indicated.
labrum. (U. S. Dept. of (U. S. Dept. of
Agriculture.) Agriculture.)

portion extending upwards conically into the heart of the trunk.
The newest burrows were evidently close to the outer sides of the
cone, next to or in living wood. Adult beetles of Parandra brunnea
were found in crevices in the broken end, and a number were seen
flying near by at dusk. Another tree with a similar history is
shown in Fig. 1. :

An examination of the shade trees in various parts of Urbana
shows very many trees in similar condition. There is a small cavity
formed by the decay of an injured or amputated projecting root-
head, and a slope of comminuted decayed wood in the opening,
fallen from the workings above. On this one may occasionally see
a red-brown wing case or other fragment of the adult Parandra.

72

COMPARISON WITH ROUND-HEADED APPLE-TREE BORER

So little is published of this insect as a fruit-tree borer that its
work has probably been commonly attributed to the round-headed
borer, from which, however, it may be easily distinguished. The
white larva, about an inch long, resembles a round-head (ceram-
bycid) larva, but is somewhat more cylindrical, and is distinctly
different in the aspect of the head and thorax. The head is small
and attached at the lower anterior edge of the thorax, rather than
centrally as in the common round-headed apple borer, The thorax is

quite thick and its upper anterior edge is very prominent. This larva -

has been fully described by Osten-Sacken (Proc. Ent. Soc. Phila.,

Vol. I, p. 118). The adult beetle of the round-headed apple -

borer (Saperda candida) is brown with white stripes, and about an
inch long, but the Parandra adult is chestnut red-brown in color,
and of a narrow oblong form, quite parallel-sided and somewhat
flattened. The round-headed borer attacks the branches more than
the trunk, working under the bark and boring into the wood; the
Parandra, while there are numerous records of its occurrence under
bark, appears to be more commonly a heart-wood borer, working in
the lower part of the trunk.

LIFE HISTORY

There is probably not more than one generation in a year. Our
larvee collected in December became adults July 17 to August 7.
Pupz were reported abundant in July. The adults were seen flying
about actively at dusk August 5. According to Snyder,* the adults
fly from July to September. Our latest date for the adult in gen-
eral collections is September 25. Snyder says the eggs are probably
laid from August to October. The presence in one case of numer-
ous larve over half grown August 27, just subsequent to a period
of pupation and emergence, and the fact that Gahan bred adults in
July, 1908, from larvz obtained December, 1906, indicates the
probability of a two-year period.

SUMMARY

To summarize, fruit and small trees of all kinds, including ever-
greens, frequently become infested by this species at the base, es-
pecially where an injury or amputation has caused the beginnings
of decay; the larve work upward and outward from the center,
completely riddling the heart-wood, apparently entering living
tissue, greatly accelerating the decay of the base to a mere shell,
thus causing the death or fall of the tree; the conditions along city
streets are favorable to its attack; the seriousness and extent of its
injury have not been fully appreciated, and in the case of fruit
trees this has been confused with that of the round-headed borer,

*Bull)94, Ptol Bur, Hnt., UO. S.Dept. Aer. pe 4:

73

from which its work may be distinguished by the fact that it is most-
ly in the heart-wood at the base, instead of under the bark of the
branches—its larva, by its thick thorax and small low-set head—
and its adult, by its chestnut red-brown color, not gray with con-
spicuous broad white stripes.

ANOMALA BINOTATA GYLL.

There are several species related to the common May-beetles,
which in the larval form are closely similar, except for their smaller
size, to the white-grubs, or May-beetle larvze, not only in general
appearance, but more or less in habits also. Among these are the
various species of Anomala. Like the May-beetles, the Anomala
beetles are well-known leaf-eaters; but scarcely anything is def-
initely known of the life histories of the species in their immature
stages. The following observations on Anomala binotata, altho
incomplete, seem worthy of publication.

In the spring of 1907 the beetles were noticed in unusual num-
bers near Leroy, McLean county, by Mr. E. O. G. Kelly, at that
time an assistant of this office. They were first found by him March
29, among old corn roots. May 8 they began to fly and were
seen on the wing all day long in oats and wheat fields. By the
roth of the month they had become quite abundant in all fields and
grass lands. May 17 they were especially numerous in corn fields,
some of them mating, and females were making vertical burrows in
the ground for the purpose of laying their eggs. As if to attract
the males, those resting on the ground sometimes spread their
wings and antennz, and soon thereafter one or more males flew
against the wind to each female, and copulation followed. In one
case this lasted 35 minutes, after which the female entered a nearby
burrow, presumably prepared by her. Mating operations continued
until May 20, and the beetles were still present May 28, when Mr.

‘Kelly ended his work at this place.

In the fall of 1907 (September 13 to October 16) another as-
sistant of the office, Mr. J. J. Davis, while collecting white-grubs
behind the plow in various parts of central Ilinois, noticed con-
siderable numbers of small pupe very similar to those of May-
beetles except for the much smaller size; and these were shown by
rearing to be Anomala binotata. The first adult was found in the
field October 3 within a pupal cell, and the last, October 21. Pupe
collected September 13 and 17 gave adults September 18 and 28,
and another lot, taken October 9, became adult October 12 to 26.
In all, 18 adults and 58 pupz were found in the fields examined.
Each of the pupze was accompanied by the cast larval skin, and all
had evidently been formed during the summer or fall.

74

From these data it is plain that the species transforms in the
ground in fall and spends the winter in the adult stage in the pupal
cells. About the middle of May they are to be fonad emerging,
flying and mating by day. The larve feed during midsummer, and
in September the pupa! stage predominates, transformation to the
adult beginning early in October, and probably being c¢ompleted
by the end of this month.

Of the 116 fields examined by Mr. Davis, pupz or adults were
found in 30, all but one of which had been in oats, that one being
in sugar corn. These 30 fields were in 10 counties of central Illi-
nois.

The larva of Anomala binotata is known to me only thru the
cast skins found in cells with undoubted Anomala pupe. So far
as structural characters are concerned, I find no evident difference
by which these may be distinguished from young Lachnosterna
larve of the type assigned to L. fusca. The sensory areas of the
last antennal joint are relatively large in comparison with those of
Lachnosterna, those of the inferior surface—on the same side as
the apical tooth of the preceding segment—being quite narrowly
separated. The double row of spines, hooked hairs, ete., of the
ventral surface of the last abdominal segment are about as in the
larva assigned to Lachnosterna fusca, there being about 17 or 18
spines in each of the two rows.

basset

Fig.6. Anomala bino- Fig. 7. Lachnosterna implic-
tata, abdominal spir- ita, abdominal spiracle of
acle of pupa. pupa.

The pupa is easily distinguished from that of Lachnosterna by
its smaller size, narrower head, depressed and broadly rounded tip
of abdomen—this in Lachnosterna being quite pointed, ending in
two thick fleshy spines—and by evident differences in the spiracles.
In Lachnosterna (Fig. 7) these are small circular openings with
a sharp raised rim. In Anomala (Fig. 6) they are large ovoid
areas marked off by a fine dark line, concolorous with the sur-
rounding surface and not raised above it; the opening a vertical
slit.

“som

75

The adult (Fig. 8) resembles a Lachnosterma, but is much
smaller, only half an inch long or less, the thorax uniform blackish,
the elytra each with a vaguely defined small dark spot near the
center. It is decidedly hairy beneath, about as in Lachnosterna.
The inner claw of the anterior tarsi is cleft, and differs consider-
ably in the two sexes. In the female it is not greatly flexed, and
the divisions are nearly of the same size, the lower slightly shorter.
In the male the claw is strongly flexed, and the upper division is
slender and short, only about half as long as the lower division,
which is large and broad.

Fig. 8&8 dAnomala binotata, adult female.
Length about three-eighths inch.

THE GREEN FRUIT-woRMS
(Teniocampa and Xylina)

The green fruit-worms (Fig. 9, 10) are quite unlike the other
common fruit pests in appearance and method of injury. They are
smooth green caterpillars, an inch to an inch and a half long, very
similar to common cutworms except in their color, which is a light
green, with whitish or yellowish stripes, usually one on each side
and one down the middle of the back. Their principal injury is
done by boring or eating a large deep cavity in the young fruit,
as is well shown in the illustrations. They do not spin any web
nor let themselves down by a thread when disturbed, as tree cater-
pillars so often do, but curl up and drop like a cutworm. ‘They
not only injure the fruit of the apple, peach, plum, pear, quince
and other orchard trees, but also eat the leaves of these trees; and
they often feed in numbers on the leaves of several common forest
and shade trees, which at times are largely defoliated by them. A

76

single larva may spoil several young fruits before reaching ma-
turity ; one was observed to destroy six out of eight young quinces
on a tree.

Altho the green fruit-worms were introduced to Illinois fruit
growers as early as 1870 by Dr. C. V. Riley, who in the American
Entomologist and Botanist noted the identifications of specimens
for three Illinois growers, they have not as yet received the atten-
tion they merit, considering that they have repeatedly damaged the
apple crop of Illinois to a considerable degree.

Fig. 10. Green Fruit-
worm, Xylina antennata,
larvaat work. Natural
size. (Cornell Experi-
ment Station.)

Fig. 9. Green Fruit-worm, 7@nio-
campa alia? (Xylina laticinerea of Sling-
erland),larvaat work. Natural size.
(Cornell Experiment Station.)

Mr. A. J. Dunlap, of Olney, reported to us that several varieties
in his apple orchards had suffered to a great extent, the Akin being
especially badly damaged; Mr. Geo. W. Emerick, of Sumner, who
has 100 acres in apples, stated that they were very common in his
orchards, damaging his crop to the extent of about $1,000, as many
as 7 percent of. the apples on some trees having been badly eaten;
and Hon. H. M. Dunlap reported considerable loss, so much that
he was planning additional spraying on this account. In the Clay
county experimental orchards of the State Experiment Station great
damage was caused the same season by these worms.

In many cases these worms have proved on breeding to belong
to the genus Xylina. Our fullest and most satisfactory account of

77

the different larvee of this genus known to cause injuries to fruits
was published by Prof. M. V. Slingerland in Bulletin 123 of the
Cornell Experiment Station, On the Pacific coast it has been found
that species of T@niocampa are very destructive in orchards, one
eating the fruit buds and then the leaves when they appear, another
eating out cavities in the fruit after the manner of Xylina. The lar-
vee observed by us in Illinois apparently all belonged to T@niocampa
alia and Xylina antennata, the former being decidedly the more
abundant. Tentocampa alia was reared by Fitch on apple leaves
about 1856, and consequently appears in Lintner’s lists of apple
insects.

The eastern species are widely distributed in the United States
and Canada, and serious injury due to them has been reported from
Canada, New York, Michigan and Missouri.

Fig.11. Green Fruit-worm, 7wniocampa alia(?), larva, enlarged.
(Cornell Experiment Station.)

Fig. 12. Green Fruit-worm, Xylina antennata, larva, en-
larged. (Cornell Experiment Station.)

The larvee feed during May and early June. When mature they
enter the ground, and by muscular movements form a smooth-walled
cavity one to three inches below the surface. Our collections of
these pupze show that, as a rule, they are within an inch of the sur-
face, sometimes even on the surface beneath leaves and other rub-
bish within the area overspread by the branches of the tree. Xylina
spins a thin cocoon within the cavity; Teniocampa does not. In this
cavity they change to a dark brown mummy-like chrysalis, or pupa.
This change takes place in T@niocampa soon after the formation of

78

the cavity, and the pupa remains therein during the remainder of
the season and over winter, emerging early in spring as a brown
moth. The larve of Xylina antennata, on the other hand, remain
in the cavity unchanged until late summer or early fall and then
change to the pupa, emerging just about a month later as gray moths,
which winter over about the bases of the trees. In any case the
moths lay their eggs in spring, and there is probably only one gen-
eration of larvee in a season.

The usual method of destroying these pests is to spray the
trees with an arsenical poison. On account, however, of the small
amount of the surface of the fruit eaten away by them, it has
been found necessary to increase the frequency and strength of the
applications to the limit of safety. The best time for spraying is
when the larve are still quite young and just beginning to attack the
fruit. This is about the first of May in the southern half of Lllinois,
and a week or more later northward.

Slingerland suggests jarring the trees, as for the plum-curculio,
and says that this can be made more effective by encircling the
trunk with some sticky band to prevent the caterpillars jarred down
from climbing back into the tree. This method has already been
used successfully in California against the Teniocampa lJarve, and
may prove to be the most effective way of dealing with the fruit-
worms generally. Koebele says of T@niocampa pacifica that if a
tree be only slightly shaken, all the full-grown larve will drop, and
that by jarring trees in the early morning the worms may be gath-
ered and destroyed.

Feeding exposed, as they do, these caterpillars are too subject
to destruction by parasites and other enemies to become injuriously
numerous every year, and it is only now and then, under circum-
stances unusually favorable to them, that they multiply at a rate to
bring them to the serious attention of the fruit grower.

TARNIOCAMPA ALIA GUEN.

The species bred by us to T@niocampa alia was collected mostly
in the pupal stage from the soil beneath apple trees. Our larve
were mostly Nylina antennata; the few larve of T@niocampa that
were taken were not recognized as different from the others until
they had reached the pupal stage, and the examples preserved do
not show the color pattern distinctly enough to permit a compari-
son with those of the species of Xylina. Slingerland’s rearings
demonstrated that there were in New York three species of Xylina
among the green fruit-worms, antennata, grotei and laticinerea. In
larval pattern and pupal structure (according to him) Jaticinerea
differs markedly from the other two. The Te@niocampa pup
closely agree with those of X. laticinerea, as described by Slinger-

19

land, and were very naturally supposed to be that species un-
til the adults were obtained.

It would be quite surprising if two species so closely related as
Xylina antennata and laticinerea evidently are, should have dis-
tinctly unlike larvee and pupze; and it is possible that Slingerland’s
laticinerca larve and pupe were really T@niocampa. Dr. William -
Barnes has very lately secured eggs from an undoubted Jaticinerea
adult, and reared these again to the adult. He very kindly showed
me the larve and sent me some of the pupz, and they seem ex-
actly like those of antennata.

Out of 6 larve and pupe taken from earth under apple trees at
Carbondale, 5 were recognized as antennata, and proven to be such
by rearing; but elsew here the other type—bred by Slingerland to
laticinerea and by us to T@niocampa alia—greatly predominated in
our collections. Of 31 pupz from Flora, Centralia and Olney, 28
were of this type, the other three being antennata.

Larvee of alia were collected May 11, 12, 15 and 22. . The date
of maturing and entering the ground for pupation is recorded as
May 27 in two different - years, and May 24; that of pupation, as
May 24 (7), 30; and June 1,2 and 7. The interval between enter-
ing the ground and pupation was 4 to 6 days. No imagos have
ever been bred or collected by us in fall; the pupze remained as such
during the remainder of the season and the winter following, emerg-
ing in spring. The first adult to appear was probably hastened by
conditions of rearing; it emerged March 21, and the others appeared
April 2 and May 14. Adults have been taken by us at lights and
Ssicat. pril 1,0, 11, 12) 13 a4, 15;and. 290 and May 8

Fig. 13. Green Fruit-worm, Teniocampa
alia. pupa: c,natural size: d, enlarged; e,
lip of abdomen. (Cornell Experiment Sta-
tion.)

The pupa (Fig. 13) is of the usual form, dark chestnut-brown,
about 15 mm. long, the dorsum terminating at the posterior end in a

80

small knob bearing a pair of stout diverging spines. The dorsum is
moderately rugose and sparsely punctate on the thorax and the first
three abdominal segments; the remaining segments are smooth and
more shiny. Segments 4—7 have at their anterior margin, above,
a row of large punctures, becoming blackish and very large and deep
toward the median line. Segment 6 is sparsely punctate laterally;
the anterior half of segment 7 laterally and segment g laterally and
dorsally are moderately punctate; segment 7 ventrally and on the
anterior half and segment 8 thruout are finely and rather densely
punctulate; and 5 and 6 are grooved on the median ventral line,
flattened below and angulated each side of this at the location of the
false feet.

XYLINA ANTENNATA WALK:

Our larve of this species taken on apple leaves were collected
May 12 and 27, except one which was found as late as July 7. One
larva matured and entered the earth May 22, and another July 14.
Unlike the preceding species, pupation does not usually take place
in a few days after the larva enters the ground, but seems to occur
irregularly thruout a considerable period, and is usually delayed
until fall. Of five individuals found July 25 in cells in the ground
under apple trees, four were still in the larval stage, and one was a
pupa. In our breeding-cages pupation took place August 19, 20 and
31, and September 3 and 10. The pupal period averaged about 32
days. The adults emerged August 17 (from a pupa found August
I), September 16 and 19, and October 7 and 8. Another series of
larvee, taken in a different year, gave 15 adults, emerging Septem-
ber 16, 28, 29 and 30, October 9, 10, 14, 15 and 16; two appeared
October 9, and four on the toth. None of this lot hibernated as
pup. Slingerland’s dates of emergence of this species ranged from
September 13 to October 6. The adults winter over, and may be
captured in winter and early spring; very likely some may not
emerge till spring. Two of our pup which did not transform at
all were apparently alive and healthy in the early part of the winter,
and probably adults would have emerged in spring if under normal
conditions. Our dates of capture of adults are September 29, Oc-
tober 31, December 14 and 18 (in fallen leaves), February 24,
March 17, 21, 22, and April 1. Slingerland lists dates from August
4 to April 20, with two records for May without exact date.

The pupa (Fig. 14) differs from that of T@ntocampa alia in the
following minor details. It is impunctate and shining, and without
any el grooves or angulations on segments 5 ae 6 of the ab-
domen, tho the anterior margin of each abdominal segment bears a
narrow band of rather dense, fine punctures; the terminal knob is
longitudinally wrinkled above, and bears two large spinous filaments

81

set close together and parallel, their tips curled outwards, also four
smaller and lighter-colored ones about half as long, similarly

straight, and curled at tip,

Fig. 14. Green Fruit-worm, Xylina antennata,
pupa: c, enlarged (natural size about as in
Fig. 13, c); d, tipof abdomen. (Cornell Exper*~-
ment Station.)

Fig. 15. Green Fruit-

worm, Xylina anten-
nata, adult moth at
rest, natural size.
(Cornell Experiment
Station.)

Fig. 16. Green Fruit-worm, Xylina Fig. 17. Green Fruit-worm, Xyling
antennata,adult. (Cornell Experiment laticinerea, adult. (Cornell Experiment?
Station.) Station.)

82

The known differences between the green fruit-worm species
may be tabulated as follows.

Larve:

Yellowish green; lateral stripe broad, including the spiracles;
piliform spots white, distinct; a few white dots in the
ground color.

Upper edge of lateral stripe irregularly indented and in-
terrupted; subdorsal stripe narrow, but continuous.
CP igte cn cete Eo nan oe X. antennata
Upper edge of lateral stripe even and sharply defined; sub-
dorsal stripe discontinuous, represented by 3 or 4 spots
ON Gach SeeMiene we | fit t ke einer inet eee X. grote
Light apple-green, sometimes with a bluish cast, all stripes nar-
row; lateral stripe running above the spiracles except at
each end; ground color finely mottled with cream-colored
dots. (Teniocampa alia?) (Fie. EI) ne taoe so cee
PREY SONA Pa Lh TAR er apc Ser X. laticinerea (Slingerland)

Pupe (Slingerland) :
With cocoon; terminal knob bearing two large and four small
parallel spinous filaments, curled up at tips (Fig. 14).....
Pre ere Rte Mra eS Satya, Paes X. antennata and grote
Without cocoon; terminal knob bearing a pair of stout diver-
gent spines apically, one on each side (Fig. 13). (Te@nio-
COMPO SAUA?.)).. zoe eae eee X. laticinerea

Pupe@ (this office) :

With cocoon; terminal knob as described by Slingerland for
antennata; each abdominal segment with narrow band of
fine punctuation at anterior margin, otherwise impunctuate.
(Pig <a es ee eens. scene eet eee ee X. antennata

Without cocoon; terminal knob as in Slingerland’s Jaticinerea;
abdominal segments 4—7 above with a single row of coarse
punctures, median ones very large and deep; all of seg-
ment 8 and the anterior half ventrally of 7 finely and
rather densely punctulate. (Fig. 13.)....T@niocampa alia

Life History:
Mostly passing the summer as larve; pupating and emerging
in fall and hibernating as adults..X. antennata and grotei
Passing the summer, and mostly or entirely hibernating, as
pips, -and* emerome<in spring ofr. peeeet tae ee
Sor te sceeeeeae XMlina laticinerea (?), Tentocampa alia

‘

- antl

83

THE APPLE FLEA-WEEVIL
(Orchestes canus Horn)

The apple flea-weevil is a small, dull blackish beetle (Fig. 18)
nearly one-eighth of an inch long, resembling the common flea-
beetles in ge eaeral appearance; and, altho a true weevil or snout-
beetle, it has the power of leaping ike the flea-beetles. The larve
(Fig. 19) make winding burrows (mines) in apple leaves; the
pupe (Fig. 20) are formed within the leaf; and the adults feed

on the Jeaves, making numerous shallow pits which later become
small holes.

Fig. 18. Apple Flea-weevil,
Orchestes canus, adult. Length
about one-eighth inch,

Fig. 20. Apple
Flea-weevil, Or-
chestes canus, pu-
pa, seen from be-

Fig. 19. Apple Lows. diene th
Flea-weevil, O7r- about one-eighth
chestes canus, lar- inch.

va. Length about
one-eighth inch.

54

The species was first found injurious to the apple by the
writer and Mr. E. S. G. Titus in 1901 at various points in the
apple region of the southern third of Illinois, when, as assistants
of the Entomologist’s office, we were making a study of apple in-
sects in that part of the state. It was again found the following
season by Mr. ‘Titus, and by Mr. E. P. Taylor in 1905, thruout
the same region, and in western Illinois by the writer in 1906. — It
was at first supposed to be Orchestes pallicornis Say, and the first
published account of its injuries appeared under that name in the
Transactions of the Hlinois State Horticultural Society for 1gor.

APPEARANCE AND AMOUNT OF INJURY

The completed mine (Fig. 21) is conspicuous as a rather bright
red blotch about one-fourth of an inch in diameter, somewhere
along the margin of the leaf near its outer end; and the pupal
chamber is indicated by a dark brown gall-like swelling near the

]

|

Fig. 21. Apple Flea-weevil, Or-
chestes canus, mine of larva in apple
leaf.

center of this blotch. Often the small passage mined by the newly
hatched larva is seen leading from the inner part of the leaf to the
mined area. “Mr. Taylor noticed that there was always a small
swelling on one of the principal veins near the point where the
larva first began to mine the leaf, and he assumed that this indi-

85

cated the point where the female beetle inserted the egg which pro-
duced the larva. This swelling was always on the lower side of
the leaf, and caused the vein to angle slightly upwards at this point,
noticeably tilting up the part of the leaf beyond the injury.

The beetles, in feeding, eat out the soft tissue between the
smaller veinlets, but leave the surface layer of the opposite side,
thus making a minute shallow pit one-half to one millimeter in
diameter (one-fiftieth to one-twenty-fifth of an inch) closed at the
bottom: by a more or less transparent membrane, which is the dry
epidermis of the opposite side. These pits are usually in groups
of two or more, separated only by the veinlets and a little leatf-
tissue. The beetles usually feed on the lower surface, but some-
times on the upper surface also, especially on woolly-leaved varieties.
As an effect of these injuries the leaves become ragged near the
tip and riddled with small holes.

Injuries by this species are not uncommon thruout south-
ern Illinois, and in some places were abundant enough to be of
economic importance. In one orchard Mr. Taylor counted fifty-
eight mined leaves on a single branch three feet long, and col-
lected several hundred leaves bearing the characteristic pupal cham-
ber. In another orchard, visited by Mr. Titus and the writer, the
beetles were very abundant on the leaves, which were thickly and
conspicuously peppered with small pits.

LIFE HISTORY AND HABITS

The eggs are apparently inserted in the outer part of the leaf
in one of the principal veins. The young larva begins to mine the
leaf near by, invariably starting toward the outer margin. Upon
nearing this it enlarges the mine in all directions, obliterating all
or a large part of its original passageway. ‘The mine remains quite
flat until the larva is about full-grown, when it becomes hemispher-
ical above and slightly swollen below; and in the chamber thus
formed the larva pupates. The adults emerge from the chamber
by breaking it open at the center on either the upper or the lower
side. When touched they leap away with a quick snap, like the
flea-beetles; when the leaf on which they are feeding is disturbed,
they feign death and drop to the ground.

The earliest date for this insect is April 27, for the completed
leaf mines at Carbondale; the earliest record for the adult is in a
note by Taylor to the effect that he has seen the beetles abroad for
several days before May 15. The adults have emerged in largest
numbers during the last week in May from many mines collected
in different years, and the latest date of emergence was June 4. The
beetles were seen by us on apple leaves thru the month of June,

86

but not thereafter. The beetles winter over and lay their eggs soon
after the leaves open, adults of the new generation appearing from
the first part of May to the first part of June, and continuing at
least thru the latter month. The remainder of the life history is
unknown.

DISTRIBUTION OF SPECIES

The species was first recognized and described by Dr. G. H.
Horn in 1878, from specimens of the adult from Michigan and
Colorado,

In Illinois we have seen it or its characteristic injuries at about
thirty different towns: in Pulaski, Union, Jackson and Williamson
counties in extreme southern Illinois; in the prairie fruit region of
Washington, Jefferson, Marion, Clay, Wayne, Edwards and Rich-
land counties; in Jersey, Calhoun and Pike counties in the western
part of the state; and in Coles and Christian counties in south-
central Illinois. It is represented in our collections by several speci-
mens labeled “N. Ill.”, and by one from Normal, McLean county;
and it will probably be found to infest apple trees thruout the state.

NATURAL CHECKS AND REMEDIES

The species is probably usually kept under control by a chalcid
parasite (a species of Eulophus, according to Mr. A. A. Girault),
which has been reared by us three times. In mines collected May
8 and 22 pupe were found May 21 and 25, and adults of this
species were secured May 26 and 27. From material collected
May 15 a considerable number of these parasites were bred May 30
and June 3.

The injuries caused by the apple flea-weevil do not as yet ap-
pear to be serious enough to make insecticide applications necessary.
If they were, an arsenical spray applied near the end of May, would
no doubt kill the beetles, since they are at that time feeding on the
leaves. Especial care would be necessary to reach the lower sides
of the leaves with the spray, since they feed mostly on that side,
and do not eat thru the leaf.

THE SrrRaAWBERRY LEAF-ROLLER
(Ancylis comptana Frol.)

This troublesome enemy of the strawberry grower is an active,
small, slender, greenish larva (Fig. 22, a, b, d) about half an inch
long when full-grown, and having seven pairs of legs. It folds
the strawberry leaf, living within the fold, where it spins a silken
web and feeds on the leaf tissue. The foliage is often thus seri-

87

ously injured, and the quality of the fruit correspondingly affected.
The brown pupa is formed within the fold, and in time changes to
a small miller (Fig. 22, c) about two-fifths of an inch across the
spread wings, the front wings red-brown, marked with white lines
and spots, the hind wings dark gray.

Fig. 22. Strawberry lLeaf-roller, <Ancylis
comptana; a, larva, natural size; 0, head and
fore part of larva, seen from above; c, adult
moth; @, posterior end of larvaseen from above.

As we lack exact information concerning the number of genera-
tions and other details of the life history of this insect, experiments
and observations on this subject were made in the fall of 1905 and
during 1906 by Mr. J. J. Davis, an assistant of this office. Table I
tabulates the life history data obtained by him, starting with the
first brood in spring and tracing the appearance and period, in days,
of the successive stages of the four broods thruout the season, as
‘they appeared in the different years, using a separate line for each
brood of each year.

TABLE I

Eggs first Egg Larve be- |Larval| Pupation Pupal Adults
noticed period |gan hatching| period occurred /period emerged

Aug. 3-17 |8 days.| Aug. 12-16
een (26 examples) (2 (11 examples)
&: Mean, Aug. 7 |exam.)|Mean, Aug. 14
> Aug. 19 (from Aug. 25 4
a 08 adults emerg- (Larve col- pntes April 21-25 ? May 2
ing Aug. 16) lected Aug. 31

June 3-22 ; :
Jun. 11?-Jul.
(Pupe collect-}| 10-++ SOF
ed June 16.) | days | Jume 18-26

July 25-31
Aug. 18-22 |6-8 da.

(13 examples)|Mean,| Aug. 24-29
Mean, Aug. 20] 6.7 da.

Sept. 4 winter

It will be noticed that Davis collected in the field larve of the
last (fourth) brood August 1, 1905. These pupated August 3-17
and the adults began to emerge August 12. August 16, two
emerged, a total of 11 in all, and these two and the remaining
pupz were transferred to another breeding cage. Eggs were no-
ticed in this cage August 19, and larve hatched from them August
25, but subsequently died. Fresh larvae were then collected in the

88

field August 31, and these wintered over in the cages in this stage.
Examinations of field conditions December 13 showed the species
to be abundantly present in the larval stage only. The hibernating
larve in the cages pupated between the 21st and 25th of the fol-
lowing April, and adults emerged May 2. This generation may be
regarded as the first of the year. Eggs from these adults, begin-
ning the second generation, were seen May 2-4, and began to hatch
May 13. Pupation occurred June 3-11, and adults appeared June
11 (?) and 19. In another lot of larvz of this brood, pupation oc-
curred June 17-22, and the adult stage was reached June 23-
July 1. No eggs of the third generation were secured from
these adults, but additional pupz of the second generation from
the field June 16 gave adults June 18-26, from which eggs of the
third generation were obtained beginning June 23. These began to
hatch June 29. The larve pupated July 19-23 and these pupe
became adults July 25-31. Eggs of the fourth generation from
these adults were first noted July 28, and these hatched August 2
and 3. Thirteen larve pupated August 18-22, and gave adults Au-
gust 24-29. This fourth generation may properly be correlated
with the larve of August 1, the pupze of August 3-17, and the
adults of August 12 and later, of the preceding season. From the
adults of August 24-29 eggs were obtained August 31, from which
larvee began to hatch September 4, which entered the winter with-
out transformation, belonging therefore to the first generation of
the following season.

The species produces consequently four generations in central
Illinois, not two or three as has been previously supposed. ‘Table
II shows graphically the distribution of generations and stages
thruout the season.

TABLE II

The egg period in the second generation, in early May was 9
or 10 days; during the remainder of the season it was 5 or 6 days.
The larval period, except that of the hibernating generation, varied
from 29 days in May to 16 in July. The pupal period of the third
and fourth generations varied from 6 to 10 days; the maximum
for the second generation was at least 10 days and probably more.

The eggs are oval and flattened, varying in size from .4.5 mm.
to .6X.7 mm. They are placed singly, very closely attached and

89

inconspicuous, on the lower surface of the leaves, usually along the
principal veins. Young leaves, which have many fine hairs on the
under surface, are freest from them.

The newly hatched larva is not more than 1.25 mm. long. It
feeds at first exposed, mostly on the under surface, gnawing the
epidermis as do most young caterpillars, and not cutting thru the
‘leaf. A few days later it begins to make a web and roll up the leaf,
eating holes entirely thru it. The hibernating larve were first
seen to feed April 21, only a few days before pupation.

The pupa is invariably formed within the rolled leaf.

The adults copulate soon after emergence. Copulation has been
observed on three different occasions, in all cases between 8 :30 and
- 9:30 p. m. Egg-laying begins within two or three days after
emergence.

The two remedies most frequently recommended are burning
over the fields after harvest, and spraying the plants with some
arsenical poison in spring when the larve are hatching, and before
they have rolled the leaves to any extent. The latter period comes
so soon before the ripening of the first fruit that some other plan is
very desirable. It is a common practice to consider infested fields
as worthless and to destroy them by plowing after harvest. Mr.
Fred Hubbard, an enterprising strawberry grower of Urbana, con-
ceived the idea of spraying his fields after harvest, and representa-
tives of this office have investigated the results. The spray used
was arsenate of lead, 134 pounds of lead acetate and 11 ounces of
arsenate of soda to 100 gallons of water. The field was sprayed
once a week from the close of the harvest until frost. Four rows in
the middle of the field were left as checks. A thoro examina-
tion of the field after the close of the spraying gave the most posi-
tive evidence of its good effect. The unsprayed rows could readily
be picked out. The sprayed plants had more foliage, and it was
all of a healthy rich green color, while the foliage of the unsprayed
rows was discolored and less abundant. The larvee were very com-
mon on the unsprayed rows and entirely absent from the sprayed
rows.

The effect of this treatment upon the crops of the succeeding
season was marred by two facts: first, the reinfestation of the
sprayed rows from the adjoining unsprayed ones left as checks;
second, the general reduction of numbers among the leaf-rollers
due to natural causes. Strawberry fields everywhere, regardless of
treatment, were comparatively free from them that season and a
good crop of fruit was secured. If the entire field had been sprayed
there is every reason to suppose that even under the most favorable
conditions for leaf-rollers the field would not have again become
infested the following spring, and that no damage to the crop from
this cause would have occurred.

90

THE STRAWBERRY CROWN-GIRDLER
(Otiorhynchus ovatus Linn.) Z

This insect is a black snout-beetle about one-fifth of an inch
long, which feeds on a great variety of plants, and occasionally
makes itself a nuisance to housekeepers by swarming into houses
in the fall. Its larva is a small whitish grub which girdles the
crown of the strawberry and feeds on the roots of strawberry,
white clover, grasses and other plants.

Serious injury was done by this insect, in 1905, to the straw-
berry beds of Mr. Geo. Wirt, at Alpha, Ill. The excellent observa-
tions of its peculiar habits reported at about the same time by the
experiment stations of Maine and Montana, together with our own
observations in connection with the Alpha outbreak, make possible
a fairly satisfactory account of this insect and of the best methods
of destroying it. It is northern in its distribution, occurring mostly
in the northern half of the United States and in Canada, altho
there is a record of its occurrence as far south as Santa Fe, N. M.

LITERATURE

It was first reported as a strawberry insect by C. M. Weed in
1884 (14th Mich. Hort. Soc: Rep:,-p. 84)... In 1895,, Dr. Lantner,
State Entomologist of New York, discussed it in his roth report, p.
416, especially because of the annoyance caused by its peculiar
habit of infesting houses. In 1899 its serious injuries in Minne-
sota were noted by Mr. Lugger in his 5th report as State Ento-
mologist. In December, 1904, Mr. R. A. Cooley, State Entomolo-
gist of Montana, reported careful observations in connection with
destructive outbreaks at two localities in his state, in his second re-
port (Bull. 55 of the Montana Exper. Sta., p. 130). In Maine,
Miss Edith M. Patch, Entomologist of the Experiment Station
there, has published valuable observations on the life history of
the species in Bulletin 123, and it was briefly treated as a corn in-
sect in the 23d report of the [linois State Entomologist.

STAGES

In its larval form the strawberry crown-girdler is a short, thick-
bodied, footless, small white grub about three-eighths of an inch
long, with a yellowish head. It is very similar in appearance to
the larva of the plum-curculio. It devours the roots and rootlets of
the strawberry, and gnaws the crown of the plant, mostly on the
outside, often completely girdling it, whence its name of crown-
girdler. There are several other small larve which feed on the
strawberry roots and crown, whose life histories and distinctive

on

characters are treated in the 13th report of this office, pp. 141, 142
and 143. These are the strawberry crown-miner (Anarsia lineatella)
—easily recognized as a slender, reddish caterpillar with numerous
short legs—and several beetle larvee similar in form to the crown-
girdler, but somewhat smaller when adult. One of the most im-
portant of these is the true strawberry crown-borer (Tyloderma
fragarve), also a footless grub, which mines the interior of the
crown, within which it changes to the pupa. The crown-girdler, on
the other hand, feeds mostly externally on crown and roots, and
pupates in the earth near by. Very similar in habits to the crown-
girdler are the three species of strawberry root-worms (Typoph-
orus canellus, Colaspis brunnea, and Scelodonta nebulosus), all
larve of the plant-beetle family Chrysomelid@; but these all have
a pair of small but distinct legs on each of the three segments
just back of the head.

The mature larva forms a cell in the earth near by, where
it changes to a whitish inactive pupa, which in about ten days
becomes an adult.

Fig. 23. Strawberry Crown-
girdler, Otiorhynchus ovatus,
aout Length about one-fifth
inch,

The adult (Fig. 23) is a black snout-beetle, or weevil, about a
fifth of an inch long, with a short, thick snout or beak. The straw-
berry crown-borer is also a snout-beetle, but has a slender beak.
The crown-girdler adult is easily recognized, also, by its curiously
globular thorax and egg-shaped hind-body, in conjunction with its
black color and its wrinkled, uneven surface, all well shown in the
figure. These beetles hide by day about the summit of the crown,
forming burrows about the bases of the leaf-stems for convenient
access, and feed by night on the leaves, eating small, irregular

92

patches from them, and gnawing the leaf-stems and even to some
extent the crown and roots.

FOOD PLANTS

The species does not by any means confine its attacks to the
strawberry plant, but is in fact a very general feeder. The larve
are also known to breed freely in the roots of wild strawberry,
white clover, balsam-root (Balsamorhiza sagittata, a western plant),
Potentilla glandulosa (another western species), and on timothy,
June grass, Poa flava (P. serotina), and other grasses. We have
in Illinois two species of Potentilla, which are common weeds
closely related to the strawberry, and probably these and numer-
ous others also serve as food plants for the larve. The adult
beetle is a still more general feeder, eating the leaves of the plants
whose roots are eaten by it in the larva stage. It also feeds on the
corn plant, and on several others. Miss Patch gives a list of 54
species upon which the beetles fed more or less readily when con-
fined for a period not exceeding three days with the leaves or the
blossoms. We once found the beetles at the roots of pumpkin.

LIFE HISTORY

The species undoubtedly spends the winter as a beetle, and,
according to Cooley, in the larval stage also. We have found what
were probably hibernating beetles twice in early April, and also in
October. At the time of the Alpha outbreak, May 26, the larve,
which were almost certainly from eggs laid by hibernating beetles,
had mostly completed their growth and changed to pupze, and a few
had become adult. From a number of pupz placed in breeding
cages, adults emerged at frequent intervals thruout June. ‘These
adults were confined with strawberry plants, and from them a num-
ber of eggs were secured in the latter part of June. A few weeks
later the eggs had well-developed larve within them, and some ap-
parently hatched, but if so, they failed to develop on the roots of
the plants, as none could be found, altho a most careful search
for them was made.

Cooley had somewhat better results. He collected adults late
in May, presumably of the hibernating generation, from which he
was very successful in securing the eggs in June, most of which
were scattered thru the soil and in the burrows made by the
adults, and late in June, after a period of about 20 days from the
laying of the first eggs, a few young larve were discovered. He
did not succeed in rearing them, however. These probably repre-
sented the first larval generation of the year, the dates being a
little later than those for this generation in central Illinois, but not

93

so late as the eggs in our breeding cages, which seem to belong to
a second generation. Adult beetles believed to be of this second
generation were found abundantly by us August 21, in the grass in
the apple orchard of H. M. Dunlap, at Savoy, not far from Ur-
bana, but not near any strawberry bed. Some of these beetles
were put in a cage with the grass (Agrotis major) in which they
were found. They lived until late in September, finally dying,
probably as the result of artificial conditions, but no signs of feed-
ing or oviposition could be discovered. Cooley remarks that the
beetles come together, as if for hibernation, as early as August, and
that the periods of the different stages overlap, so that it is very
difficult to determine the number of generations, all stages being
found together at the same time, the indications being, however,
that there is but one generation a year in his state. In Illinois, as
shown by our observations, there are apparently two generations of
larvee, one in May and one in July, the first becoming adult in June
and the second in August, the latter hibernating until the follow-
ing April.
OTHER BIOLOGICAL DATA

A peculiar feature of the occurrence of this species in unusual
numbers is its limitation to very small areas, and the lack of any
decided tendency to scatter widely and infest large areas when
its numbers become excessive. This is probably due to the fact
that the adults are wingless, their wing-covers being solidly grown
together, so that they can not fly; hence their only means of dis-
persal is by crawling, except when they are introduced into a new
district on strawberry plants from an infested field. Mr. Cooley
has suggested that they may be limited by certain soil conditions;
but this seems unlikely. That they do migrate to some extent in
search of suitable winter quarters is shown by their entering houses.

In the Alpha strawberry fields, the principal infested plot had
shown injury over two small areas the preceding spring, which was
the third spring after planting. The more severe injury was still
limited to these areas, but there was now evidence of injury in
other parts of this plot, and also in the edge of another, adjacent.
Two plots, separated from these only by a lane, showed no sign of
the insect or its injury.

The infested leaves were reddened and small, and the crowns
were so weakened by injury and decay that the plants and a layer
of straw on the ground could readily be rolled up together like a
carpet. Larvee and pupze were very numerous, mostly about two
inches below the surface; the adults were less numerous and were
well hidden in the straw and among the lower leaves. In Maine,
an area of three square feet in an infested patch was carefully ex-
amined, and more than 200 individuals, nearly grown larve, pupe,

94

J

and adults, were found. More than half of the plants were killed.
At one infested spot in Montana the species has prevented the prof-
itable growing of strawberries for eight or ten years.

Like the box-elder bug, these beetles have perhaps attracted
more attention by entering houses when in search of winter quarters
than by their injuries to the strawberry plant. In late summer they
wander about in large numbers in the neighborhood of infested
strawberry plots, and if a house happens to be near by they often
come into it in astonishing numbers. In one case more than four
hundred were killed in one evening in a single room, and the beetles
traveled all over the house, crawling up the walls to the ceiling only
to drop to the floor, and making this journey over and over again.
They are not attracted by lights, as some have supposed.

REMEDIAL MEASURES

From experiments made by us, and also at the Montana sta-
tion, it appears that the beetles avoid leaves which have been sprayed
with arsenical poisons, and feed then upon other parts of the plant.

On the other hand, notwithstanding the general feeding habits
of both larva and adult, there is evidence that a satisfactory rotation
can be arranged that will completely clear an infested plot. Miss
Patch examined one infested area in which there were no culti-
vated strawberry plants. She fotind the larve infesting roots of
wild strawberry, grasses, and white clover, but an examination of
large potato fields close at hand revealed no signs of the insect. Mr.
Cooley also suggests the potato as a possible crop for this purpose.
He suggests that infestation of strawberry plots probably does not
originate among the strawberries, but is due to the planting of
ground already infested. In this connection the history of the
Alpha plot is of interest. It was used for a strawberry crop, then
set with young fruit trees for two or three years, then used again
for strawberries, the injury first being noted in the third season of
this second planting to strawberries. Cooley mentions an instance
in Montana where infested strawberry land was planted to other
crops for a few years, and when subsequently replanted with straw-
berries was not re-infested.

THE BLACKBERRY [EAF-ROLLER

(Exartema permundanum Clem.)

The larve of this leaf-roller were found at Decatur, IIl., June
25, 1905, feeding in small numbers on blackberry, raspberry and
strawberry plants.

They were reared to the adult (Fig. 24) in the insectary, and
the moths deposited eggs, singly, on the glass of the breeding cage.

95

The eggs are yellow at first, and are oval in outline, measuring
about 434 of a millimeter. In about five days the young larve
hatched, and at once formed a nest by drawing several of the
young leaves together. At first they ate only the epidermis in ir-
regular patches, but when they grew older they ate thru the leaf.

From the original larve, collected June 25, adults were obtained
July 5-17. The first eggs from these adults were laid July 12, and
hatched on the 17th. The larve grew slowly, and September 7,
when only about four millimeters long, they began to prepare for
hibernation. A part of the outer edge of the leaf, half an inch or
less in length, was folded over upon the upper surface nearly to the
midrib, each larva thus forming a shelter for the winter.

Fig. 24. Blackberry Leaf-
roller, Hxartema permunua-
num, adult moth, with out-
line showing natural size.
(Saunders.)

One larva passed the winter successfully, and came out about the
first of April, but was not fed until April 21, when a strawberry
plant was put into the cage, and was at once fed upon. The larva
pupated May 28, and the adult emerged early in June.

The larvee taken at Decatur June 25 apparently came from eggs
laid by moths from hibernating larvee, and in that case the species
apparently normally produces two generations. Two exceptions to
the above life history which appeared in the cages indicate that
there is some variation in this respect. One of the original larvee
did not pupate and become adult with the others in July, but re-
mained in the larval stage and folded the leaf as if for hibernation ;
it died, however, before the arrival of winter. On the other hand,
one of the next generation of larve did not winter over with its
fellows, but pupated, yielding a moth the same season, August 15.

BLAcK GNATS IN CUCUMBER HOUSES
(Sciara sp.)
From time to time complaints have come to us from the cucum-
ber forcing-houses of northwestern Illinois, particularly from Dixon

and Morrison, county seats of the two adjoining counties of Lee
and Whiteside, respectively, of a serious wilting of cucumber

96

plants, associated with the appearance of swarms of small, black-
ish, gnat-like flies. An assistant of the office, Mr. E. C. Green, was
sent to the scene of the injury to investigate and experiment, and
this account is mainly a summary of the results secured by him
then.

The flies belong to the family Mycctophilide, or fungus flies,
and to the genus Sciara. The larvee of this large family seem to feed
primarily on decaying vegetable matter, and records of their directly
attacking healthy living plant tissues are rare. However, as is
often the case with insects of this habit, their presence in decayed
parts of plants, or even in close association with plants, seems in
some way to promote decay. The larve of this genus are small,
slender, glassy white, footless maggots, a third of an inch long or
less, and usually with black heads. A species common in wet corn
fields following sod, which sometimes eats the softened seed corn,
especially in cold, wet springs, is treated in the eighteenth report
of this office, where it is called the black-headed grass-maggot. The
frequent occurrence of similar larve in rich soil, especially in flower-
pots and greenhouses, is also mentioned in that article.

Mr. Green found numerous cases of the excessive abundance of
such larve in the soil of forcing-house benches, and swarms of the
flies, often in such numbers as to blacken the woodwork. The close
association of these maggots with wilted and ruined beds of plants, —
and the invariable presence of numerous larve about the bases and
roots of wilting plants, strongly indicate that these larve were the
cause of the injury.

When the cucumber plant wilts in the presence of these Sciara
larvee, the lower leaves are affected first. These droop and finally
hang down, gradually dying from the edges inward until the w hole
leaf is dried and shriveled. The rootlets and smaller roots of wilted
plants are dark-colored and dead. The maggots are usually exces-
sively numerous in the soil about such plants, often especially so
about the main stalk. In no case were the maggots found attack-
ing a firm, healthy stalk or root, but at the least appearance of decay
they attacked it in great numbers, gnawing the surface and tunnel-
ing thru it in all directions. If the larve are full-grown and
rapidly pupating at the time, and the flies are also beginning to ap-
pear in large numbers, the plant usually survives the injury without
assistance, showing signs of recovery in a day or two. An exami-
nation of a plant at this stage shows numberless little, white, new
rootlets starting from the main stalk and larger roots. If, how-
ever, the maggots remain and continue their work several days after
the first wilting of the plants, these do not recover.

In the fields these maggots have been noticed mostly in May
and June, but indoors and in hothouses they may occur at any time
of the year, and the life cycle is probably rather short, so that there

may be quite a number of generations in the course of a year. Some
freshly-laid eggs of this species, gathered January 13 and placed
under glass, hatched about gightcen days later.

Mr. Green made experiments to determine the food preferences
of the larve. A cucumber plant was potted in clean sand, and 100
of the maggots were placed about its base. These affected the
plant, the stem being evidently eaten by them. The same experiment
was made with the addition, at one side of the pot, of a cubic inch
of decayed horse manure, such as is mixed with earth in growing
cucumbers. The larvze were subsequently found collected about the
piece of manure and the plant remained uninjured. Next a plant
was potted in a mixture of manure with earth from the forcing beds
infested by maggots. The plant was not injured. These experi-
ments, although on too small a scale to be decisive, confirm the
supposition that the maggots feed preferably on decaying manure,
injury to the living plants resulting o1 aly in case the farvee are @Xx-
cessively abundant.

A very careful and extended study was made by Mr. Green
of the history of infested beds at Dixon and Morrison, with espe-
cial reference to the source and treatment of the manure mixed
with the earth used in making up cucumber beds. Severe infesta-
tion invariably followed the use of fresh horse manure in fall.
For example, in one case beds were started in the fall with soil from
an old pasture mixed with fresh horse manure. When the plants
were about five inches high they suddenly wilted and all died, and
the flies soon came out in such numbers as to cloud the glass in the
houses. The whole place was thoroly cleaned and whitewashed,
and a new start was made with more manure from the same source
and earth from a nearby cultivated field. Serious injury again
followed, and the flies became as thick as before.

In another case manure was collected from livery barns, and in
late summer and fall some fresh manure was added, also soil from
river alluvium and old land, and the beds were started with the
mixture. Four weeks later the plants began to wilt and about
three-fourths of them died. In a similar case as to material used
the soil was steamed three hours, but without apparent effect, as
the flies became very thick and about 50 percent of the plants
were lost.

When the manure used was gathered in winter or early sum-
mer and well rotted before using, little or no injury followed.

In another class of instances, where the manure used was com-
_ posted with lime, no injury resulted unless, as was frequently the
case, fresh manure was added to make up a deficiency, when the
injury varied with the amount of fresh manure used. In one case
the infestation was slight at first, but reached serious proportions
by the next spring. In another case the additional fresh manure

98

was all used on a certain bed, the other beds being prepared with
composted manure. The bed with fresh manure was a total loss;
the others showed no injury. The ruined bed was simply replanted,
and there was no further injury. In another case the manure, al-
tho obtained in fall, heated greatly in rotting, and no serious in-
jury followed its use. ‘i

One fact observed by Mr. Green may be of value in combating
these pests. He found them much less numerous and troublesome
in the drier houses than in those where water was freely used and
moist conditions prevailed.

It was thought that perhaps some repellent might be intro-
duced about the bases of the plants to drive away the maggots, and
Nickoteen, a proprietary decoction of tobacco stems, was tried for
this purpose. It was found that % of 1 percent of Nickoteen in
water repelled the larve without injuring the plants. A 6 percerit
application of Nickoteen caused a temporary wilting of the plants
and higher percentages killed them.

One curious result of the Nickoteen application should be espe-
cially noted. In an infested forcing house 135 feet long, contain-
ing three benches, the east bench was treated with 1 percent Nicko-
teen, a gallon to each rod of bench, the west bench with 2 percent,
a gallon to each yard, and the middle bench was left as a check.
The treatment of both side benches had the effect of precipitating
the transformation of the larve. These pupated prematurely, with-
out waiting for complete development, and soon clouds of flies
darkened the interior of the houses. These flies seemed to be
weakened by their hasty transformation and died in unusual num-
bers. Evidently, in cases of sudden wilting, when speedy relief
might mean the saving of a large part of the crop, such a treat-
ment might be of great value, and further experimentation with
this and similar insecticides is especially to be desired.

To summarize the results of the investigation, it may be said
that all cases of severe injury to cucumbers in the forcing houses
followed the use of fresh horse manure in fall; that if the manure
had been gathered earlier in the season and well rotted or composted
with lime, or gathered in winter, little or no damage appeared; that
the injury was much worse in the moister forcing houses than 1n
the drier ones; that Nickoteen in water, in strengths of ™% to about
6 percent, will force the insects prematurely thru their trans-
formations to the adult stage, weakening them so that many die;
and that if the injury be of short duration the plants are likely
to recover, but that if it continues more than a few days the plants
will die and the crop may be a total loss.

ON THE MORE IMPORTANT INSECTS OF THE
TRUCK-FARM AND VEGETABLE GARDEN

By J. J. Davis, ASSISTANT ENTOMOLOGIST FOR NORTHERN ILLINOIS

Vegetable gardening is now one of the most important of the
various agricultural interests of Illinois. According to the census
of 1900 there were 256,213 acres in vegetables in Illinois in 1899,
and the value of the products amounted to $10,346,797, this being
the fourth largest valuation of such products for all the states. The
average valuation of vegetables was $42.09 per acre, while that of
all crops taken together was but $10.04. Altho the gardening
industry in Illinois, and especially in Cook county and counties ad-
joining, has greatly increased since 1899, the figures for that year
serve to indicate the relatively great importance of vegetable-grow-
ing in Illinois.

Chicago is the principal center of the truck-garden industry of
this state, and for a distance of 12 to 18 miles north, south, and
west of the city, agriculture is almost wholly gardening. This area
is especially well adapted to such farming, as the more or less sandy
character of the soil permits early tillage—a very important fact
from the truck gardener’s point of view, since it enables him to get
his products on the market at an early date, while prices are still
high. Cook county growers have a market close at hand, so that
they can personally dispose of their produce, making sales from their
own wagons, thus avoiding freight and commission charges.
Further, Chicago affords an ample supply of manure for continuous
fertilization, which is absolutely necessary where such intensive
farming is practiced, and where so much is taken from the soil each
year.

Another important consideration is the labor supply; for such
crops as onions and cucumbers require large numbers of laborers at
certain times of the year, and in isolated localities and in small
towns there is usually insufficient help in the busiest parts of the
season. In Cook county, however, the city of Chicago can usually
furnish all the labor required, and at a cheaper rate than in remote
localities.

Probably the most important garden product of Illinois is the
potato. The area in this crop in Illinois in 1899 was 139,464 acres,
and the estimated value of the product was $4,702,033. In Cook
county alone there were 15,336 acres in potatoes. Onions and cab-
bage are important crops, as are also asparagus, celery, beets, and
that class of vegetables known as general truck, which includes rad-
ishes, lettuce, parsnips, carrots, rhubarb, beans, etc. The growing

100

of sweet corn, tomatoes, beans and peas for canning, and of cucum-
bers for pickling, is becoming a prominent industry, and the same is
(rue of melon-growing in many parts of the state. Cucumbers, to-
matoes, lettuce, and radishes are extensively grown in hothouses,
as well as out-of-doors.

The gardening regions are more or less divided into areas in
each of which a certain class of products is cultivated. For example,
a strip of ground half a mile or a mile in width may be used for
onion culture almost exclusively, or it may be in potatoes or cabbage,
or both, or it may be devoted to general gardening.

The more intensive the culture of a crop, the more important be-
comes the control of its insect enemies. Land is especially desirable
for vegetable gardens near the market centers, and as these are al-
most invariably large cities, such land has a high value, and the
greatest possible returns must be realized from it. To insure this

va

the control of injurious insects becomes of great, if not prime, im- -

portance.

GENERAL FARM METHODS FOR THE CONTROL OF INSECTS

Clean Culture.—Probably the most valuable of all farm practices
for the control of insects is clean culture, by which is meant the
clearing away of all useless vegetation, and the numerous other
general measures which leave for insects no sufficient winter shel-
ter, or adequate protection from the weather, the birds, and other
natural checks upon their numbers. In fall, rubbish of every kind,
and especially standing unmarketable cabbages and onions, should
be collected and destroyed, to deprive insects of their breeding and
hiding places. These methods are particularly helpful in destroy-
ing cabbage and onion maggots, cutworms, thrips, plant-lice, potato-
beetles, and striped cucumber-beetles. In the summer likewise, and
especially early in spring, it is important to keep down the weeds,
for they promote a rapid multiplication of insects, and provide tem-
porary breeding places for some species pending the appearance of
their special garden food-plants. An early cutting of weeds is fur-
ther beneficial by preventing their seeding.

Importance of Healthy and Vigorous Plants.—I\t is a common
observation that healthy and vigorous plants withstand the attacks
of insects much better than weak and neglected ones. One of the
principal requirements for vigorous growth is fertility of the soil.
Good seed is necessarily an important item, and, further, it should
be properly planted and the crop should be thoroly cultivated to
secure strong and healthy plants.. Such plants will also endure the
effects of drouth for a much longer time than weaker plants.

Rotation of Crops.—Crop rotation is one of the most valuable
of the cultural methods for preventing insect attack. As a rule, it

MS cae

101

is bad practice in truck-gardening to grow two successive crops of a
vegetable, or of nearly related vegetables, successively, on the same
piece of land; and, further, a crop should be planted as far as possi-
ble from the location of the same vegetable the year before. Es-
pecially is rotation desirable when the crop was badly damaged by
insects the previous year. Some of the more important insects
whose injuries may be checked or controlled by this method, are cab-
bage and onion maggots, potato-beetles, wireworms, white-grubs,
and cutworms.

Fall Plowing.—Another important means of insect control is
fall plowing. In the northern part of Illinois, where the winters are
usually severe, the value of this measure seems considerable, for its
main object is to bring the insects in the soil nearer to the surface,
where they may be killed by the cold. It is necessary in such locali-
ties to plow as late in fall as possible, when the insects are more or
less inactive and unable to go very deep into the ground. Disking
and harrowing in the fall is often helpful.

Time of Planting.—It is often possible to avoid insect attack by
either early or late spring planting. The object in planting early is
to have the crop well started and sufficiently advanced to withstand
insect attack when it occurs; while the object of late planting is to
bring the crop on after the disappearance of the insect likely to in-
jure it. I have known of but one instance of such benefit derived
from early planting, and this was in the case of the onion-maggot.
Late spring planting is a successful measure of protection against
some insects, such as cutworms, the striped cucumber-beetle, flea-
beetles, ete.

Early Detection of the Presence of Insect Pests —Usually an in-
sect has already done much damage to a crop before its presence 1s
known, and often it is discovered too late for the successful applica-
tion of remedies. This makes it necessary for the gardener to keep
vigilant watch of his crops in order to know when to spray or other-
wise to treat them; that is to say, he should detect the presence of
an injurious insect in his garden almost as soon as it appears.

Insect injury may be recognized by the actual detection of the
culprit; by the failure of seed to germinate; by injury to the leaves;
by a wilting of the plants; by the wilting or curling of the leaves,
caused by aphis attack; by an uneven stand; or by the slow growth
of the plants.

The more important insects known to be injuring garden prod-
ucts in Illinois will now be discussed under the various crops, taken
up in alphabetical order. Methods of preparing the principal in-
secticides used by the gardener are given at the end of the article.

102

ASPARAGUS

The area in asparagus has greatly increased in Illinois in the
last few years, and the plant is now one of the most important prod-
ucts of several gardening districts. Only one insect—the common
asparagus-beetle (Crioceris asparagi Linn.) has been found doing
any considerable damage to this crop, and this in only two locali-
ties.* Where present, however, it is an important pest of this plant,

Sy
SW Sy
SATO
, Yi Yd. N )

ZAK J

Fig. 1. Common Asparagts-beetle, Crioceris asparagi, larve
and adults, on asparagus. Natural size. (Chittenden.)

and the increasing acreage in asparagus may cause its spread over
a much larger territory. The asparagus grower should be on the
continual lookout for it, and at its first appearance take immediate

measures for its control.

*Since the above was written it has been found in other localities, and it is
probably only a matter of a few years until it will become common thruout our

asparagus-growing districts.

103

THE COMMON ASPARAGUS-BEETLE
Crioceris asparagi Linn.

Both beetles and larve of this species cause injury by feeding on
the young shoots as they appear above ground, and by defoliating
the plants later in the season. In the first case the young shoots are
rendered unsalable or of poor quality, while the loss of foliage
greatly weakens the plants. especially seedlings.

Fig. 2. Common Asparagus-beetle, Crioceris asparagi: a, beetle;
b, egg; c, newly hatched larva; d, full-grown larva;
e, pupa. Enlarged as indicated. (Chittenden.)

The beetle (Fig. 2, a) is one-sixth to one-fourth of an inch in
length, and is gaily colored, the thorax being reddish, and the elytra,
or wing-covers, more or less striped with lemon-yellow and dark
blue, and having a reddish border. Early in spring, at the time of
the first cutting of asparagus, the beetles emerge from their winter
quarters and lay their conspicuous, yellowish, slender eggs (Fig.
2, b) end to end, in rows of eight or less, on the stalks or leaves of
the asparagus plants. In our experiments a single female, in con-
finement with a male beetle, laid a total of 386 eggs during her life
of 29 days—from May 13 to June 11. In about a week the eggs
hatch into “grubs,” or larve (Fig. 2, c), which immediately begin
to feed. These become full grown (Fig. 2, d) in about two weeks,
or less, at which time they are a quarter of an inch in length, or
slightly shorter, fleshy, and of an olive color. The mature larve go
into the earth and change to pupe (Fig. 2, e) just beneath the
surface.

They remain in this condition nine to twelve days, and then
change to beetles, which, in turn, come out of the ground and lay
eggs for a second generation. The beetles of this generation go
into hibernation in the fall, about the middle of September in ordi-
nary seasons. It is not certain that there are but two broods a year
in Illinois; the life history has not been completely worked out for
this state, but observations made in northern Illinois indicate that in
ordinary seasons from two to three broods occur there. We have

104

succeeded in raising three broods in one season in confinement, un-
der what were probably optimum conditions, in the latitude of
Chicago.

Methods of Control.—Volunteer asparagus plants should be
kept down in early spring, as they afford a good breeding place for
the larvee. Since the shoots are cut for the market every day or
two, the eggs which may be deposited on them do not have time
to hatch; and if the volunteer growth is kept down there will be
little chance of any eggs hatching in the field.

Fresh air-slaked lime, dusted on the plants early in the morning,
while the dew is on, has been reported by Dr. F. H. Chittenden as
destructive to all grubs with which it comes in contact.

Arsenical poisons are of value upon plants that are not being cut
for food, and possess the advantage of destroying beetles, as well
as grubs. The application should be made at frequent intervals, or
as often as the larve reappear. Arsenate of lead or Paris green in
water are excellent sprays for this purpose. Dry arsenicals are also
effective—as Paris green mixed with lime, with lime and flour, or
with land-plaster.

CABBAGE AND CAULIFLOWER

In Cook county gardens, cabbage and cauliflower rank in 1m-
portance with such garden products as onions, cucumbers, and pota-
toes. Not only are they among the most generally grown vegeta-
bles, but they are peculiarly susceptible to insect attack. In Ilinois
I have found the following insects doing noticeable damage to these
crops: the imported or green cabbage- -worm, cutworms, the root-
maggot, plant-lice, and flea-beetles,

THE [MpoRTED CABBAGE-WORM
Pontia rape Linn.
(Pieris rape)

There is not a gardener who is unfamiliar with this common and
destructive caterpillar. There are several “cabbage-worms,” but the
commonest is the larva of the «white butterfly (Pontia rape) al-
ways to be found flying around cabbages in the summer. It emerges
early in spring, having passed the winter in the chrysalis or pupa
stage. The greenish eggs, small, slender, and ribbed, are soon de-
posited, usually singly, on the leaves of early cabbages or other
cruciferous plants. “The velvety green larva (Fig. 3, a) begins to
feed ravenously on the leaves immediately upon hatching. It gets
its growth in ten to fourteen days and becomes a chrysalis (Fig. 3,
b), changing to a white butterfly (Fig. 4 and 5) some eight to twelve

——"

105

days later. The length of the season and other general conditions
have much influence in determining the number of generations in

Fig. 3. Cabbage Butterfly, Pontia rape: a, larva; b, pupa.
Natural size.

any year. There are certainly as many as three, on an average, in
northern Illinois.

These caterpillars are not only injurious to cabbage, cauliflower,
and other cruciferous plants, but they sometimes do much damage
to lettuce.

Fig. 4. Cabbage Butterfly, Pontia rape, male, natural size.

Fig. 5. Cabbage Butterfly, Pontia rape, female, natural size.

Parasites.—There is hardly a field of cabbage or cauliflower in-
fested with these green caterpillars in which we can not find masses
of small white or yellowish cocoons. These cocoons are formed by
small larvae which live within the bodies of the cabbage-worms, soon

106

killing their hosts. Minute wasp-like adults emerge from the co-
coons, and deposit eggs in the bodies of other cabbage-worms. This
parasite (Apanteles glomeratus) is a valuable friend to the cabbage
and cauliflower grower, and it is sometimes abundant enough to free
the field of cabbage-worms, at least for the time being. Many gar-
deners make the serious mistake of destroying the cocoons of this
parasite, believing them to be the eggs of the white butterfly.

Another parasite, Pteromalus puparum, kills many pup, or
chrysalides, of this cabbage-worm, and materially decreases the num-
ber of the next generation. Often the chrysalides from which the
butterfly should have emerged, are dark brownish to black, and when
broken open will be found to contain many maggot-like larve or
dark brown pup. These have developed from eggs deposited in
the living chrysalides by adults of Pteromalus puparum, which, like
the parasite of the larve, is a small wasp-like insect. I have reared
48 to 58 of these parasites from single chrysalides.

In one large gardening district where cabbage and cauliflower
are grown extensively, I could not find a single living worm or
chrysalis August 26, 1908, altho a few weeks before both had been
abundant. All had been killed by their parasites.

Remedial Measures—The following remedies are equally ef-
fective for any of the several caterpillars feeding on cabbage leaves,
with the exception of cutworms, which will be treated later.

The use of arsenicals on cabbage and cauliflower is often dis-
couraged because of the supposed danger to the consumer. Experi-
ments with arsenate of lead and Paris green have been made, both
in New York and in Kentucky, in which the sprayed plants were
analyzed to determine the amount of poison remaining on them.
It was found that only a slight trace, if any, was present—in no
case enough to be dangerous, even if all were consumed by one per-
son. Cauliflower, however, should not be sprayed after the ‘‘flower”’
has begun to form, nor should cabbages be sprayed after they are
two-thirds grown.

Paris green is one of the standard remedies, and is more used
today in spraying for cabbage-worms than any other insecticide. It
may be applied dry or suspended in water, and specific directions for
either use of it are given at the end of this article (pages 149-150).
A resin-lime mixture has been highly recommended by Mr. F. A.
Sirrine,* who, after experiments with it, concluded that the yield of
cabbages was increased 60 to 100 percent by the treatment. He
figures the cost of it at about $2.00 an acre. Two applications are
usually sufficient. Directions for the preparation of this mixture
also may be found on page 150.

*A Spraying Mixture for Cauliflower and Cabbage-worms., Bull. N. Y. Agr.
Exper. Station, No. 144 (Sept., 1808). Geneva.

107

Arsenate of lead has been successfully used against the cabbage-
worm, but has the disadvantage of not adhering as well as the resin-
lime mixture, altho better than Paris green alone. It must conse-
quently be applied oftener—sometimes as many as three or four
times a year, but ordinarily only twice. It has the advantage of be-
ing easy to prepare, and, as it is white, one can easily see eed the
plants have been thoroly sprayed.

Pyrethrum is also recommended for this insect. It is more ex-
pensive than the arsenicals, but has the two advantages over them
that it is not injurious to man, and that it can be used later in the
season than they—that is, when the heads are nearly formed.

Hot water at nearly boiling point will, of course, kill the worms,
and is said to be harmless to the plants. Lime has been used against
these worms, but it is ineffective, especially when they are numerous.
Professor J. W. Lloyd says* “Cabbage-worms were abundant late
in the season, and in spite of five applications of air-slaked lime did
considerable damage to the crop.”

Cabbage stalks and other debris should be removed from the
field in fall and burned, unless, as recommended by Dr. F. H. Chit-
tenden,t a few of the plants are left and poisoned as bait for the last
generation of the insects.

THE VARIEGATED CUTWORM
Peridroma margaritosa Haw.
(Agrotis saucia, Peridroma saucia)

Cutworms are sometimes very injurious to cabbage, cutting off
the young plants and killing them outright. For this reason they
are a worse pest than the green caterpillars; but they are not so wide-
spread, and are therefore of less economic importance. The life
history-of the above species and a description of it are given in con-
nection with insects affecting lettuce (pages 129-130).

Remedies.—Poisoned bait (see page 131) is probably the best
remedy for cutworms. If they are known to be present, the bait
should be put on the prepared field just before the cabbage plants
are set out. - If not, it should be used as soon as the presence of cut-
worms is recognized.

Spraying with an arsenical poison, such as Paris green, will de-
stroy some of the insects if the spray is applied to the stems near
the ground; but the stalks are probably more frequently cut off just
below the surface of the ground than just above it, and in the former
case the poison would not be eaten by the cutworms.

The collection of cutworms by hand is advised for some crops,
but it would generally be too expensive for large cabbage fields.

*The Farmer’s Vegetable Garden. Bull. Ill. Agr. Exper. Station, No. 105

(Feb., 1906), p. 190.
tInsects Injurious to Vegetables, p. 139. Orange Judd Co., New York. 1907

108

THE CABBAGE ROOT-MAGGOT
Phorbia brassice Bouché
(Pegomyia brassice, Anthomyia brassice)

One of the most destructive enemies of cabbage and cauliflower
in Illinois is the cabbage root-maggot. It is white or cream colored,
resembling the onion-maggot (Fig. 26), which is known to all Ili-
nois gardeners. It is one of the immature stages of a fly which is
much like the house-fly in appearance, but more cylindrical, some-
what smaller, and of a grayish or brownish color. The winter may be
passed in either the adult, puparium, or maggot stage, the flies hiber-
nating in rubbish, buildings, or any accessible place that will afford
shelter, the puparia in onion bulbs left in the fields in the soil, and the
maggots in the refuse bulbs. Early in spring the flies deposit their
small, elliptical white eggs in small cracks and crevices near the
stem of the plant, or on the stem beneath the surface. Usually
within a week—not so soon if the weather is cool, but often within
24 or 36 hours in the warmer parts of the year—small maggots
hatch from the eggs, and immediately go into the ground and begin
to feed on the roots or stalk. Becoming full grown in a few weeks,
they leave the roots to pupate in the soil near by. They remain in
this dormant stage, as oval brown puparia, for about two weeks (in
summer), and from these the adult flles emerge. There may be two
or more generations in Illinois, according to the length of the season.

Most of the injury to cabbage and cauliflower by this maggot is
done while the plants are small, and particularly to early cabbage.
For this reason the acreage of early cabbage has greatly decreased
in this state within the last few years.

Economic Control.—Many methods have been recommended by
various writers for the control of the cabbage root-maggot, but most
of these are preventive rather than remedial. Cabbage seldom
brings a high price, and many measures that have been proposed
are impracticable because of their cost.

For the prevention of maggot attack in seed beds, probably the
most successful and practical method of protecting the young plants
is that of screening them, as suggested by Dr. James Fletcher,* and
later successfully demonstrated on a large scale by Mr. W. J.
Schoene.t This consists in growing the seedlings under cheap
frames, made of light wood and covered with cheese-cloth (Fig. 6),
to protect the plants from the cabbage-maggot flies. In Mr.
Schoene’s experiments it proved very successful. He says: “Plants

*Insects Injurious to Grain and Fodder Crops, Root Crops, and Vegetables.
Bull. Central Experimental Farms, Ottawa, Canada, No. 52 (June, 1905), p. 35.

tScreenings for the Protection of Cabbage Seed Beds. Bull. N. Y. Agr. Ex-
per. Station, No. 301 (March, 1908). Geneva.

109

raised under cloth grew faster and reached the desired size for trans-
planting one week before the seedlings in the check [untreated ]
area. The screened sets were seasoned by the removal of the cover-
ing thirteen days before the time of replanting, and showed no more
wilting when transplanted than did the check seedlings.”

“The screened bed was entirely free of maggots, and produced
50,000 sets, which were replanted. The check bed, of more than

cone

Fig. 6. Cabbage seed-bed with frame and screening in position,
to keep out the Cabbage Root-maggot, Phorbia brassice.
(New York Experiment Station.)

three times the size, yielded only 30,000 desirable plants. The cab-
bage maggots were generally very destructive to unprotected seed-
lings.”

The total cost for material was approximately 40 cents for each
1,000 plants. The screens not only protect the plants from maggots,
but also from the flea-beetles, which often do much damage to young
cabbage.

For the destruction of maggots at the tune when seedlings are to
be transplanted, roots not too badly infested for use should either
be washed off with water before resetting them, in order to remove
the maggots, or, as Professor F. L. Washburn suggests,* they may
be dipped in a decoction of white hellebore—one part of the powder
to two parts of water. The latter treatment is preferable, for while

*The Cabbage Maggot and other Injurious Insects of 1906. Bull. Minn.
Agr. Exper. Station, No. 100 (Dec., 1906), p. 12. St. Anthony Park.

110

the water will have no effect on the maggots except to remove some
of them, the hellebore may kill them all.

For the prevention of maggot attack after transplanting, prob-
ably the most successful measure is the use of tarred-paper cards.
Those ordinarily used are made of a thin grade of tarred felt-paper,
and are about two and a half inches in diameter. They may be of
any shape, but, as a matter of economy, are usually hexagonal, with
a slit from one side to the center. The card is placed on the piant
by separating the two edges of the slit and slipping the card around
the plant so that the stem comes in the middle of the card. The card
must then be pressed close to the stem and flat on the ground. This
being done, the female fly must lay her eggs either on the card—
where there is small chance of their hatching—or on the stem—and
if the card is close to the stem the young larve hatching from them
will be unable to reach the roots—or else on the ground beyond the
card, in which case the young larve, hatching so far from the plant,
would probably be unable to reach it.

A carbolic acid and lime mixture (see page 155) has been rec-
ommended by others, but in our experience it proved worthless, the
coat of lime cracking and leaving places for the deposit of eggs.
After 24 hours the carbolic acid loses its value as a repellent. The
mixture is applied along the rows with a sprinkling-can or spray-
nozzle as the plants are transplanted, and in such manner as to coat
the entire surface thinly around the plants.

Tobacco dust placed around the base of the plants has been
found to prevent the female from depositing her eggs on or near
them.

When these maggots have once gained a foothold in a cabbage
field it is difficult, if not impossible, to exterminate them. The only
practical insecticides which have been recommended are the carbolic
acid emulsion, a decoction of hellebore, and carbon bisulfid (see
pages 153, 154 and 158), and these have given quite variable results.
The carbon bisulfid has been used with success, but the expense of
application prohibits its use in large commercial gardens. Helle-
bore decoction has given us very good results. A third of a pint
should be poured at the base of each plant when transplanted, and
each week thereafter for three or four weeks.

In using these insecticides it is necessary to make thoro appli-
cation at the base of the plants before the maggots have had a
chance to enter the root and protect themselves.

The application of commercial fertilizers is of much value.
They stimulate the plant and make it more resistant to maggot
attacks.

Clean farming and fall plowing aid in preventing maggot
attack.

111

The use of “blood and bone,” with hellebore, was suggested to
us by a gardener, who reported that some of his cabbages had been
protected from this maggot by this means, while plants not so
treated were seriously damaged by it, as in previous years. We
tried this material this year (1910), placing a small quantity of the
dry mixture about each cabbage plant after transplanting to the
field, but, unfortunately for the test, the maggots were not present
in injurious numbers either in the treated or untreated plots, and
therefore no definite conclusions were reached. Upon examining
the “blood and bone” around the plants, however, we found in it
many maggots which were bred to adults and determined as
Phorbia fusciceps Zett.—a species closely related to the cabbage and
onion maggots, and often injurious to the same crops. The same
species infested “blood and bone” when applied to onions, the mix-
ture being in this case drilled in on each side of the row. Altho
no recommendations can be made from these tests, it is thought
best to make brief record of them.

THE CABBAGE PLANT-LOUSE
Aphis brassice Linn.

During midsummer or early fall this plant-louse becomes notice-
ably abundant on cabbage and cauliflower plants, usually infesting
the under sides of the leaves in large, packed colonies, which rapidly

“” a
ce ie
tt A ERE, s
«

; + OR Fat

Fig. 7. Cabbage Plant-louse, Aphis brassice, on head of cabbage.

112

increase in size unless checked by enemies or unfavorable weather.
Both wingless and winged individuals are to be found, and tho
there are few of the latter as compared with the multitudes of
the former, these few winged lice are the chief means of starting
colonies in uninfested fields. Like other plant-lice, the cabbage
louse gives birth during the summer months to living young, with-
out previous fertilization of the female by the male. In the fall,
as observed by Fletcher, Garman, Quaintance, and others, both
sexes are produced, and eggs are deposited on the stems and leaves
of cabbages remaining in the field. Sometimes, however, vivipar-
ous females are found as late as midwinter, within the cabbage
heads.

The lice are about the size of a pin-head, soft-bodied, pale
greenish, but completely covered with a whitish powder or bloom
which is not unlike the bloom on cabbage leaves.

Plant-lice injure cabbage by sucking the juices of the plant.
\Vhen abundant, they so disfigure and stunt it, especially the
smaller and weaker plants, that it becomes unfit for market.

Natural Checks.—lf it were not for the natural checks on its
increase, the cabbage plant-louse would be one of the very worst
pests with which the cabbage grower has to deal; but wet weather
and its insect enemies greatly restrict its multiplication. It is not
only subject to attack by many minute parasites, but it is preyed
upon by several kinds of “ladybird” beetles and by the larva of a
lacewing fly (Chrysopa), whose combined attacks greatly lessen
the numbers of the aphids, and hold them in check.

Remedies.—Probably the most successful method of dealing
with the cabbage-louse is: fumigation with carbon bisulfid. This
substance was tested by us in the fall of 1908 on cabbages badly
infested with plant-lice. Fumigation of cabbage or cauliflower
on a commercial scale with individual covers for the plants would
be too expensive for profit; but an economical method is to cover
a considerable area of plants with large canvas or muslin sheets,
with props at the corners and center, and wherever else may be
necessary.* The cover being ready, dishes are placed beneath it
containing the carbon bisulfid at the rate of a teaspoonful to each
cubic foot of space. The edges of the cloth, which should lie on
the ground, are covered with earth to prevent, as far as possible,
the escape of the fumes. After forty-five minutes to an hour the
cover may be removed. This treatment also killed the thrips and
cabbage-worms which infested the plants, but it did not kill the
parasites concealed in the aphid skins—which fact is greatly in its
favor. With exposures of 20 and 30 minutes, nearly all gf the lice
were killed; but with only 15 minutes or less, practically none were

*The Melon-louse and other Aphids, by C. E. Sanborn. Bull. Texas Agr.
Exper. Station, No. 89, (not dated) page 47. College Station.

113

killed. (For other particulars concerning the use of carbon bisulfid
see page 158.) Mr. C. E. Sanborn* has recommended the use of
“Aphis Punk’ or “Nico-Fume” paper in fumigating plants under
cover.

Kerosene emulsion of a 10 percent strength is the standard
spray for the cabbage plant-louse. Care should be taken to spray
thoroly the under side of the leaves, where the lice are usually
most abundant, for the liquid must come in contact with the insects
in order to kill them. (For formula, etc., see page 153.)

Tobacco decoction and various soap mixtures have been recom-
mended for this plant-louse, but they are less effective than the kero-
sene emulsion. It is hardly necessary to say that treatment should
begin at the first appearance of the lice.

Clean culture, especially the destruction of the cabbage and
cauliflower stalks in fall, is very important, to destroy the eggs
which are deposited on the cabbage and related plants, and like-
wise to destroy the young and adult lice which may be hibernating
on the same kinds of plants.

THE CABBAGE FLEA-BEETLE
Phyllotreta vittata Fabr.

This flea-beetle, often very abundant and destructive, is the
only one of the many flea-beetles—so named because of their re-
markable leaping ability—which has been found injuring cabbage
in northern Illinois. It is a black, shining oval beetle (Fig. 8, a)

Fig. 8. Cabbage Flea-beetle, Phyllotreta wittata: a, beetle; b,
larva. Enlarged as indicated.

about .o8 inch long, with a broad, wavy longitudinal marking of
pale yellow on each wing-cover. It sometimes injures other crops,
especially radishes, and its food plants include many weeds. It
injures plants by eating innumerable holes and pits in the leaves.

EOC uEGIt-

114

It is most destructive to cabbages early in the year, when the
plants are less than two inches high, at which stage they easily suc-
cumb to such attacks.

I quote in full the concise paragraph on the life history of the
immature stages of this flea-beetle given by Professor H. Garman.*

“The early history of the cabbage flea-beetle was made out in
1865 by Dr. Shimer, of Mt. Carroll, Illinois. He found that the
larva [Fig. 8, b] feeds on the roots of cabbage, in which respect
it is different from a very similar European beetle, and also from
the next one [P. sinuata] treated in this paper, both of them being
leaf-miners. The eggs of this beetle are placed at the base of the
plant. The grubs hatching from them work their way into the
earth, mining and feeding on the roots, in some cases completely
destroying the plants. When fully grown they are about one-fifth
inch long, yellowish white in general color, the head dark brown.
They desert the roots when ready to change to pupe, and pushing
into the earth a short distance, make a small cell, in which the
change takes place.”

Prevention and Remedies.—A useful method of preventing flea-
beetle attack recommended by Mr. W. J. Schoene,+ consists in
screening the seed beds, as described on page 108 for the protection
of seedlings against the attacks of the cabbage root-maggot. The
most effective treatment is spraying with Paris green or arsenate
of lead, using Bordeaux mixture as a diluent (see pages 151 and
152). To use Bordeaux is not absolutely necessary, but as it is
a powerful repellent it adds to the value of the spray.

Many other remedial measures have been recommended, such
as powdering the plants with air-slaked lime, soot, road dust, wood
ashes, tobacco dust, etc., these substances acting as repellents, or
with Paris green and lime—tho the latter mixture is more effective
as a liquid spray; and spraying kerosene emulsion around the base
of the plants is said to destroy the eggs and young larve of this
insect.

Cultural Methods.—As this flea-beetle feeds on many weeds,
especially the crucifers, all weeds in the immediate vicinity of the
garden should be destroyed.

CUCUMBER AND MELON

Cucumbers and melons are among the most important garden
products in Illinois. In 1899, 2,580 acres were devoted to cucum-
bers, and 466,876 bushels were marketed. This report does not
include cucumbers grown thruout the state under many hundred

*Insects Injurious to Cabbage. Bull. Ky. Agr. Exper. Station, No. 114 (June,
1904), p. 37. Lexington.
x TBull. New York Agr. Exper. Station, No. 301 (March, 1908), p. 170.
eneva.

115

thousands of square feet of glass. The same year there were 1I0,-
g63 acres in watermelons and muskmelons in Illinois. The acreage
in both these crops has greatly increased since 1899.

The most important insect enemies of these plants are, outdoors,
the striped cucumber-beetle, the squash-bug, and the melon aphis;
and, in greenhouses, thrips and the white-fly. Altho they are not
insects, two other greenhouse pests should be mentioned, namely,
the red spider, and a nematode worm commonly known as the eel-
worm.

THE STRIPED CUCUMBER-BEETLE
Diabrotica vittata Fabr.

Ordinarily this is a pest which the gardener must carefully
guard against. As the young cucumber, melon, or other cucurbita-
ceous plants make their appearance above ground, they are attacked
by these ravenous beetles, and large areas may be killed by them in
a few days.

The beetle (Fig. 9, a) is small (about two-fifths of an inch
long), with black head, yellowish thorax, and yellowish wing-

Fig. 9. Striped Cucumber-beetle, Diabrotica vittata: a, beetle;
b, larva; c, pupa; d, tip of larva, side view. Enlarged as
indicated.

covers, marked lengthwise with three black stripes. It passes the
winter in the ground or beneath boards or similar shelter, and as
the young food plants appear above ground—usually about the first
week in June—it comes forth and feeds on their leaves. If the
beetles are at all abundant they may soon devour the small, tender
plants. They feed continuously and voraciously for a week or ten
days, and then commence to pair. The eggs (Fig. 10) are de-
posited singly, and may usually be found on the under surface of
the leaf, on the stem near its base, or on the ground near the plant.
The larve (Fig. 9, b, d) upon hatching, feed within the stalks or

116

on the roots, or sometimes on the fruit and vines as they lie upon
the ground. The length of the larval period no doubt varies
greatly, depending on the food supply and climatic conditions,
The pupa (Fig. 9, c) is formed in an earthen cell in the soil, and
the transformation to the adult beetle is completed within 7 to 14
days. Altho the beetles of this new generation begin to emerge
the latter part of July, they may continue to appear thruout August.
Professor Garman, in his studies of this insect,* found that in con-

> £&
A nae
: Se o

Fig. 10. Striped Cucumber-bettle, Diabrotica vittata, egg, much
enlarged, with portion of surface more highly magnified at
right.

finement the entire life cycle of an individual was 26 to 33 days.
It is possible that a second generation may appear in the southern
part of the state, but in northern Illinois probably but One full
generation occurs under normal conditions.

Preventive and Remedial A large number and
variety of methods for the control of this insect have been recom-
mended, but only those which have given promising results will be
discussed. One of the oldest methods for protecting the young
plants from the cucumber-beetle is covering them with a screen;
but while this is very satisfactory in small gardens, it is not so
practicable on a large scale as the use of the Bordeaux mixture in
connection with a trap crop, as discussed farther on. It has been
found that for a short time in spring, before the beetles begin to
pair, they may be killed with a spray of Paris green or arsenate of
lead, but that they will not feed readily upon sprayed foliage after
pairing, and arsenicals alone can not be generally recommended
for the cucumber-beetle without further tests of their efficiency.

The use of squash as a trap crop (Fig. 11) in combination with
a spray of Bordeaux mixture or Bordeaux and arsenate of lead
on the cucumber plants and an arsenical poison on the squash, is
one of the best means of preventing the attacks of these beetles.
Mr. F. A. Sirrine has given a very complete account of this method
of treatment based on his own experiments, and the following is
taken largely from his paper.+

Squash seed is planted around the margin of the field about four
days previous to planting it with cucumbers, or other crop.t At

*Enemies of Cucumbers and Related Plants. Bull. Ky. Agr. Exper. Station,
No. 91 (March 8, 1901), p. 5. Lexington.

tCombating the Striped Beetle on Cucumbers. Bull. N. Y. Agr. Exper.
Station, No. 158 (May, 1899), pp. 14-16. Geneva.

¢Mr. Sirrine informs us that only the Hubbard or the Boston Marrow squash
should be used, these being by far the most attractive to the beetles.

6 S st ts) “i1) 3 <2
(uone}S JouIodxy YIOR MaN) ‘epooq-sroquinonyg pedis oy} JovI}}e 0} Jopsoq Sjr Suope soysenbs yim PfPy Joquunong 11 “St
y 5 ag i a N we Beta

117

118

the time of cucumber-planting there should be a second planting of
squash seed on the margins of the field. At the first appearance of
the beetles about half the squash-vines should be dusted with some
easily obtainable arsenite, and soon after the cucumber plants ap-
pear above ground they should be sprayed with Bordeaux mixture,
using the 4-4-50 formula (for preparation see page 151). At about
the same time the cucumber plants are sprayed with Bordeaux the
squash-vines should again be dusted with an arsenite. Two weeks
after the cucumber plants have appeared all but a few of the squash
plants may be removed. These should be left until the cucumber-
vines have set fruit, as the beetles will feed on the squash flowers
in preference to those of the cucumber. Sirrine recommends spray-
ing the cucumbers with Bordeaux mixture three times: first, as
soon as the seed leaves are exposed; second, when the third true
leaf appears; and last, just before the plants commence to vine.
He says: “The cost of three applications of the Bordeaux mixture
will not exceed $2.00 per acre; whereas, the cost of wire covers
would be $40.00 per acre, and they probably will not last over
three years.”’

Repellents are effective against this beetle, and Bordeaux mix-
ture is one of the best, altho it 1s best to use it in connection with
a trap crop, as above described. Other much-used repellents are
air-slaked lime, land-plaster, sifted ashes, road dust, and tobacco
dust, but these are not always effective when the beetles are
abundant.

Clean culture will prevent much of the damage usually done by
many of the common garden pests, and it is especially effective
against the cucumber-beetle. It has been recommended in this con-
nection, that as soon as the crop is harvested the vines be covered
with straw and burned. This is a far better practice than that of
gathering them up before destroying them, as the latter procedure
leaves many of the beetles undisturbed in the field.

THE SQUASH-BUG
Anasa tristis DeGeer

The squash-bug, altho confining its attacks largely to the squash
and other plants of the gourd family, is often very injurious to
the cucumber in early spring, when emerging from its winter
quarters. It finds its way into the cold frames in which the plants
are being started, when no other food plant is available.
| This large, ill-smelling, dark brown bug (Fig. 12, a) hibernates
as an adult in rubbish, sheds, and wood-piles, under loose bark on
stumps, or in any other available place of protection. In northern
Illinois the bugs make their appearance about the middle or the
last of June, or even later; but I have found most of their injury

119

to the cucumber done while the young seedlings are in the cold
frames. In all such cases these frames were near wood-piles or
out-buildings, and during the occasional warm days of spring, when

quash-bug, Anasa tristis: a, adult; b, egg cluster; c,
young in different stages. Twice natural size.

Rice aes

d,

d
Ss
Gi

the frames were opened, the bugs gained entrance, the temperature
of these beds making them fully active. Shortly after coming from
their winter quarters they deposit the conspicuous clusters of glossy
yellowish-brown eggs (Fig. 12, b), usually on the under side of
the leaves. The young, light gray bugs (Fig. 12, c) hatching from
these, immediately begin sucking the juices of the plants. In their
later immature stages (Fig. 12, d, e)—which differ only in size
from the young bug as it hatches from the egg—they feed, as do
the adults, upon the juices of the plant. The loss of sap, however,
is not the primary cause of the wilting of the plants. This is
due principally, if not wholly, to a liquid poison which the bug in-
troduces into the wound which it makes. In some cases it also
gives entrance to a bacillus which causes a wilt disease.

Methods of Control.—Collecting the bugs under board traps 1s
probably the most satisfactory of the various methods suggested
for the control of this pest. This should be done in early spring,
as soon as the bugs appear. The boards are simply laid on the
ground as a decoy shelter for them during the night, and here they
may be easily captured early in the morning. The eggs should
likewise be collected and destroyed as fast as they are laid on the
leaves.

Kerosene emulsion kills the young bugs without injuring the
plants if it is very carefully applied, but it is too dangerous for
ordinary use.

120

Here, again, clean-farming methods are of much importance
Cold frames should be placed at some distance from wood-piles
and out-buildings, and as soon as the crop has been gathered the
vines should be covered with straw or other easily inflammable
material and burned.

THE MELON APHIS
Aphis gossypu Glover
(Aphis cucumeris)
Altho the truck gardener may not have noticed the melon aphis
on his cucumber plants, a curling of the leaves (Fig. 13) is pre-
sumptive evidence of its presence in injurious numbers. It is not

only a serious outdoor pest, but it is often very injurious to cucum-
bers in greenhouses.

Fig. 13. Melon Aphis, Aphis gossypii; its work. (Chittenden.)

121

This plant-louse (Fig. 14) varies in color from pale yellowish
to blackish green. Its life history and insect enemies are very
similar to those of many other plant-lice, such as the one which has
already been discussed as a cabbage insect (page 111). Briefly, the
melon aphis appears on cucumber and melon plants early in the

Fig. 14. Melon Aphis, Aphis gossypii: a, winged female; aa,
enlarged antenna of same; ab, dark female, side view; J,
young nymph or larva; c, last stage of nymph;

d, wingless female,—all greatly enlarged.

season, and increases rapidly in numbers during the summer unless
checked by its insect enemies or by unfavorable weather. It is
still doubtful whether it ever produces eggs to carry the species over
winter, but it is known that viviparous females—the form found
thruout the summer—may hibernate in some parts of Illinois.

Remedial Measures——The measures recommended for the con-
trol of the cabbage-louse (pages 112-113) may be used against the
melon aphis, and of these, fumigation with carbon bisulfid 1s
doubtless the most efficient.

Owing to the large number of its food plants, clean culture is
especially important in dealing with the melon aphis, particularly
the cutting and burning of weeds and old vines; and fall plowing
is also advisable.

In greenhouses, fumigation with hydrocyanic acid gas is doubt-
less the best treatment for this insect. The procedure is described
on pages 150-158.

THE GREENHOUSE WHITE-FLY
Aleyrodes vaporariorum Westwood

One of the most troublesome and ‘destructive insects with which
the greenhouse vegetable-gardener must deal is the white-fly. This
file pest attacks f icaninees, tomatoes, peppers, and lettuce under
glass, and a considerable variety of flowering and ornamental
plants.

The winged adult (Fig. 16) is about .o6 (one seventeenth) of
an inch in length, and looks as if dusted with flour. The minute

122

irregularly ovoid eggs are deposited on the under surface of the
leaves, to which each is attached by a very short, slender stalk.

Fig. 15. White-fly, Aleyrodes vaporariorum, nymphs on leaf.
Twice natural size. (Connecticut Experiment Station.)

Recently hatched larve are flat, oval in outline, and transparent or
translucent according to age. They settle on the leaf close to the
empty egg-shells, soon attach themselves, and there remain ( Fig.
15), molting four times and becoming adult with the last molt.
The entire life cycle of the white-fly from the time the egg is de-

Fig. 16. White-fly, dleyrodes vaporariorum, adults on leaf. Twice
natural size. (Connecticut Experiment Station.)

posited until the adult emerges, is completed in a month to five and
a half weeks, at the ordinary greenhouse temperature in summer.

The larvee and pupz secrete a honeydew which falls on the
leaves below them; and on badly infested plants, where this liquid

123

becomes abundant, a sooty fungous growth appears on the leaves
covered with it, which hastens the death of the plants.

Parasites.—In the university greenhouse, at Urbana, many of
the plants, especially Salvia and pansy-geranium, were badly in-
fested in the midwinter of 1908 by the little white-fly, but two
months later these insects were found to have been almost exter-
minated by a minute hymenopterous parasite, which proved to be
a new species, and has since been described by Mr. A. A. Girault
as Encarsia versicolor.* It attacks the immature forms of the
white-fly, and the infested young may be recognized by their black
color, those not infested being pale greenish.

Remedies.—Fumigation with hydrocyanic acid gas is by far the
most efficient means known for controlling the white-fly in green-
houses. In ordinary greenhouses it may be used at a strength of
one ounce of cyanide of potassium’to 3,000 cubic feet of space. In
new tightly built houses a smaller quantity may be used; but in
very loosely built or weather-shrunken houses more must be used.
The mode of using this gas is described on pages 156-158. It is
commonly necessary to fumigate three or four times, at intervals
of about two weeks.

Fumigation with tobacco stems, or with any of the commercial
tobacco extracts, is partially effective against this insect, and where
the use of hydrocyanic acid gas is impracticable this treatment is
recommended (pages 159 and 160). More fumigation will be re-
quired, but, if persistently followed up, the white-fly can be kept in
check by this means.

THE ONION THRIPS
Thrips tabaci Lind.

This insect, which is very injurious to cucumber plants in the
greenhouse, is discussed in connection with its injury to the onion
(page 137). In the greenhouse its life history is the same as out-of-
doors, excepting that the life cycle varies greatly in length under
the various artificial conditions which prevail in greenhouses. As
a rule, cucumbers are started under glass in fall, and it is at this
time that the thrips migrates from outdoor vegetation into the
houses. It breeds successfully on almost any kind of greenhouse
vegetation, and may soon become well established; but it is not
usually until midwinter that it becomes abundant enough to alarm

the gardener.

Remedial Measures.—Clean culture is one of the most im-
portant means of holding this pest in check. Asa rule the grasses
*Encarsia versicolor species novum, a Eulophid Parasite of the Greenhouse

White-fly, Aleyrodes vaporariorum Westwood. Psyche, Vol. XV, No. 3 (June,
1908), pp. 53-57. Cambridge, Mass.

124

and weeds around greenhouses are badly infested with thrips in
summer, when the greenhouses are not in use, and on these plants
it continues to breed until fall, when the seed heads of such plants
as pigweed (Amarantus retroflexus), wild sunflower (Helianthus
retroflexus), and foxtail grass (Chetochloa viridis) are filled with
winged thrips ready to migrate into the houses. It is very im-
portant, consequently, that all weeds should at least be kept down
by cutting, tho it is much better to cultivate the land several times
during the summer to prevent weeds and grasses from coming up.
Cold frames to be used in starting young plants should not be
placed near an infested onion field, nor where vegetation is allowed
to grow wild.

Spraying and fumigation with tobacco extracts (pages 154 and
159) thruout the fall and winter will hold the thrips in check. The
gardener should not wait until his plants are visibly injured, but
should continually look for the insect, and as soon as the first
thrips is found, should begin operations.

Hydrocyanic acid gas has been used by some with apparent
success. In a small greenhouse containing 4,500 cubic feet of space,
we were successful in killing 99 percent of the thrips, without
injury to the cucumber plants, by using the gas at a strength of
one ounce of cyanide of potassium to 2,000 cubic feet. The maxi-
mum and minimum temperatures thruout the period of fumiga-
tion, which lasted all night, were 74° and 65° F. respectively.

Kerosene and soap emulsions (page 153) are effective against
the thrips before the plants have made much foliage, but at a later
period it is impossible to spray thoroly under the surface of all the
leaves, and as these emulsions kill by are: it is of the greatest
importance to reach all the insects.

Dipping the leaves of small plants in a soap solution just before
transplanting them to the greenhouses has been found useful w hen
plants become infested in cold frames.

THE RED SPIDER
Tetranychus bimaculatus Harvey
(Tetranychus telarius)

This common pest is a tiny mite rather than a true spider. It
has been a source of trouble to the indoor cucumber-grower for
years, and altho it can usually be kept in check by careful and
thoro cultural and spraying methods, it is a veritable pest when
it once obtains a foothold. It is a general feeder, and among the
outdoor vegetables which it often injures are celery and eggplant.

This mite (Fig. 17 and 18) is so familiar to growers that a
brief description will suffice. It is about one-fiftieth of an inch

125

long, oval, with four pairs of legs, and usually a dark spot on each
side. This latter character, however, is not constant. The general
color also varies, some mites having a decidedly reddish tint, while
others are almost colorless. They spin fine webs over the surface

Fig. 17. Red Spider, Tetranychus Fig. 18. Red Spider, Tetranychus

bimaculatus, male, greatly bimaculatus, female, greatly
magnified. magnified.

of the leaf—usually on the under side—beneath which they live,
and it is largely for this reason that they are hard to reach. The
minute eggs are globular, pale and transparent when deposited, but
later change to reddish. They are commonly placed on the under
surface of the leaf, but sometimes on other parts of the plant. The
young mites mature in about ten or twelve days.

Remedial Measures.—This pest can usually be held in check,
or even exterminated, by thoro and timely spraying of the plants
with water, if the spray is fine and the pressure considerable; but
this is a preventive rather than a remedial measure, for, owing to
the excessive rate of multiplication of the mites in a hot, dry atmos-
phere, and owing further to the fact that the web beneath which
they live becomes denser as their numbers increase, the spraying
is ineffective unless it is done while the infestation is still slight.
Indeed, no treatment is of much practical value if the mites have
become well established on living plants. A special nozzle intro-
duced by Dr. B. T. Galloway, of the U. S. Department of Agri-
culture, for use against the red spider is very effective, “as it

126

readily serves to keep the leaves in a thoroly healthy condition,
and at the same time wets the beds but little.’’*

Fumes of sulphur or hydrocyanic acid gas will kill the red
spider, but the strength required is by far greater than the plants
will stand. After the cucumber or other crop has been gathered,
and before infested vines have been removed, it is advisable to
fumigate them with one of these two substances, using one ounce
of cyanide of potassium to one hundred cubic feet of space, or
burning one pound of sulphur to one thousand cubic feet. It is
hardly necessary to say that these strengths will kill living plants.
(For full directions for the use of these materials, see pages 156
and 159.) a

Sulphur is one of the best remedies for the red spider, and
most of the remedies that have been recommended require sul-
phur as one of the ingredients. Liberally dusting the plants with
sulphur after syringing is effective, or, better, applying a spray
consisting of one ounce of sulphur to one gallon of water. A little
soap added to this sulphur solution will increase its efficiency.

Soap solutions, either whale-oil or a neutral soap such as the
“Ivory,” are of great value in the eradication of the pest, but the
addition of sulphur as mentioned above increases their value.

A lye-sulphur mixture has recently been recommended by Dr.
I’. H. Chittenden, and is said to be more effective than any of the
many other materials tested. Directions for preparing this spray.
are given on page 155.

Whatever insecticide is used, especially when the infestation
is severe, should be applied with as great pressure as practicable,
for the greatest trouble in controlling this mite arises from the diffi-
culty in penetrating the web which it spins. The stream should
also be directed to the lower surfaces of the leaves, for it is here
that the spider is most often found.

THE EEL-worRM
Hetcrodera radicicola Greeff

The eel-worm is a common pest in hothouses, particularly in-
jurious to the cucumber, and, unfortunately, it is apparently becom-

Fig. 19. Nematode worm, Heterodera radicicola, among particles of
soil. Greatly magnified. (Massachusetts Experiment Station.)

*The Common Red Spider, by F. H. Chittenden. Circ. U. S. Dept. of Agr.,
Bur. of Ent., No. 104 (Jan. 26, 1909), p. 8.

Se

E>

127

ing more widespread each year. In Illinois it is known only as
a greenhouse pest, and our observations indicate that here, at least,
it is unable to survive the winter in the field.

The only unmistakable indications of the presence of this root-
feeding worm are the swellings or enlargements of the roots (Fig.
20) often referred to by the gardener as root-knots.* These root-

Fig. 20. Cucumber roots showing galls of a nematode, Hete-
rodera radicicola. (Massachusetts Experiment Station.)

knots vary in size and shape, largely according to the number of
worms present, to their position on the roots, and to the kind of
plant. The presence of the eel-worms may be indicated by a sickly
appearance of the plant, by the dying of its leaves, and by its final
collapse, altho nothing but an examination of its roots can certainly

*This deformity should not be confused with the club-root of cabbage and
related plants, which is due to bacterial disease.

128

incriminate the species. Plants are commonly half grown or bear-
ing fruit before they are noticeably weakened by the eel-worm.
The young eel-worm (Fig. 19) is very minute and elongate.
It is provided with a spearlike organ projecting from the head, and
with this it pierces the tender root (Fig. 21), in which it ultimately
embeds itself. The worms continue to grow—in width rather than

Fig. 21. Tip of cucumber root with young nematodes, Hete-
rodera radicicola, just entering. Enlarged.
(Massachusetts Experiment Station.)

in length—within the root, the female finally becoming club-shaped,
but the male resuming its original slender form. The young, hatch-
ing from the eggs laid within the root, make their way into the soil,
and thence into new roots.

Preventive and Remedial Mecasures——Tools which have been
used in soil infested by eel-worms should be thoroly washed or,
better, sterilized before using them in other soil.

Among the most suggestive methods of treating infested green-
houses is that used by Mr. W. F. Preston, of Dixon, Illinois.
Having had serious trouble with nematodes on cucumber plants,
he used the sterilization process about to be described, but, owing
to the ‘solid bed,” worms in the unsterilized soil below soon rein-
fested the treated soil. To prevent this, a cement floor was put in
the bed about ten inches below the top, the wooden sides being
retained. The nematodes did not reappear until the following sum-
mer, when the vines were old and ready to be removed, as was
also the soil. They then gained entrance between the cement floor
of the bed and the wooden side-walls. The soil could probably be
wholly protected by making the sides as well as the floor of cement.
sloping the floor from the center towards each side, and leaving
holes along the sides, near the floor of the bed, for drainage.

7a

129

Sterilization of the soil by steam is the most efficient measure
of controlling the eel-worm, as well as many insect pests ordinarily
introduced into the greenhouse with the soil, and various ways of
accomplishing this have been devised by hothouse gardeners. Per-
haps the earliest record of this soil treatment is that of Mr. W. N.
Rudd,* of Chicago, who used it successfully in 1893. The most
practical and economical method with which I am acquainted, is
that of Mr. J. F. Ammann, of Edwardsville, Illinois. Into a steril-
izing bin of rough boards, measuring two feet high, 10 feet wide,
and 20 feet long, about a foot of soil is placed, and a heating ap-
paratus of five “runs” of old perforated two-inch pipe is laid and
connected with the steam supply. Another foot of soil is added,
and potatoes are placed in the bin, one at each end and another in
the center. The bin is then covered with a tarpaulin, and 80
pounds of steam are turned into the pipes for about an hour and
a half, or until the potatoes are well cooked.

jel BALL GK Oe

The cultivation of lettuce, tho carried on thruout the year, is
confined to hothouses during the cooler months. The hothouse
product is far the most important, and it is to this that insect pests
are the most troublesome. Cutworms, the lettuce plant-louse, and
the cabbage-worm are usually abundant enough to do it much
damage, and need the close attention of the lettuce grower.

THE VARIEGATED CUTWORM
Peridroma margaritosa Haw.
(Peridroma saucia, Agrotis saucia)

Young lettuce, cabbage, and other plants, are often cut off, or
otherwise eaten, by some unseen insect, and later the leaves may
be so badly eaten as to ruin them for market. In such cases if one
searches near the plant, just beneath the surface of the soil, he 1s
almost certain to find a grayish or dark fleshy cutworm.

The only cutworm I found feeding on lettuce and other vege-
tables in the greenhouses and out-of-doors in 1908 was the species
named above. The egg (Fig. 22, e) from which it hatches 1s
about one-fiftieth of an inch in diameter, dome-shaped, with ver-
tical ribs. When first laid it is creamy white with a pearly luster,
but it soon changes to a pinkish tint, and finally to lilac or darker.
The parent moth may deposit 500 eggs, or even more, in masses
of 60 and upwards (Fig. 22, f). The larva hatches in five or six
days, and after eating the egg-shell from which it has emerged,

*Killing Grubs in Soil. American Florist (Chicago), Vol. IX, Sept. 28, 1893,
D170.

130

begins feeding on the lettuce leaf. When full grown (Fig. 22, b, c,
d) it is about an inch and a half long. It is usually dull, blackish
brown, mottled with gray, some larve being paler and others
darker. A characteristic marking is a row of four to six yellowish
dots along the median line of the back. This cutworm feeds at

Fig. 22. Variegated Cutworm, Peridroma margaritosa: a, adult;
b, larva, side view; c, same, curled up; d, dark-colored larva,
seen from above; e, single egg; f, cluster of eggs on
twig. Ail natural size except egg.

night, and hides during the day in the soil just beneath the surface,
or under boards or rubbish near the plant. It remains a cutworm
for 25 to 30 days, and then goes into the ground and pupates in
an oval earthen cell, usually found just below the surface. Fifteen
to nineteen days later it comes out as a moth (Fig. 22, a). The
pupa is shining reddish brown, growing darker with age. It is
about an inch long, slightly pointed at one end and rounded at the
other. The moth measures about one and three quarters inches
across the expanded wings. The fore wings are brownish, mottled
with black or gray, the shades and markings varying considerably.
The hind wings are nearly uniform grayish or pale brownish, with
a darker border. Like the larva, the moth is nocturnal in habit.
and the eggs are laid at night. The adult may live a week or more,
but rarely lasts more than ten days. ‘The complete life cycle in
summer requires 45 to 54 days, but in winter, in greenhouses, the
period is much longer. Out-of-doors there are two generations in
a year, and in greenhouses probably four or more. According to
various writers the winter may be passed outdoors in either the
pupal, larval, or adult stage.

131

Natural Enemies.—A single tachinid fly (Archytes aterrima

‘Desv.)* has been bred from this cutworm in Illinois, but three

species of these flies and several hymenopterous parasites have been
reported to infest it elsewhere. None of these, however, is of
much importance in lessening its numbers.

Remedial Measures.—In the greenhouse, for such vegetables as
lettuce, insecticides may best be used in the form of a poisoned bait.
Successful experiments against cutworms were made by me in a
Chicago greenhouse this year (1908) with both poisoned bran and
poisoned lettuce leaves. In lettuce houses the latter will usually be
the most convenient. If the soil is new, and especially if it is a sod

. soil, lettuce leaves should be laid on the beds and dry Paris green

sprinkled lightly over them before the crop is planted. Or if the
lettuce has already been planted, it should be pulled up if cutworms
are abundant, and a row of lettuce leaves should be laid along each
side or in the center of the bed, and then poisoned. Even tho there
are but very few cutworms in the greenhouse, it is always best to
repeat this process at the final gathering of each crop. It is but
little trouble to lay fresh refuse leaves along the bed and sprinkle
them with the poison.

Fig. 23. Trap lantern for adults of cutworm.

A lantern trap (Fig. 23) is also useful in the greenhouse. This
consists of a tub with an inch or two of water in the bottom and
a little kerosene to form a surface film, and a lantern is hung over
the tub to be kept burning for several nights. The moths are at-

*Determined by C. A. Hart.

132

tracted by the light, and in flying around it drop into the tub and
are killed by the oil.

Outdoor plants, such as cabbages, Gece and onions, may be
protected by the use of poisoned bran mash, the formula for which
is given on page 155. This should be placed in small piles, about a
tablespoonful to a pile, at the bases of the plants. When a field
which has been in grass is to be planted to vegetables, it is well to
use the poisoned bran in spring, shortly before. planting the crop.

Dusting or spraying plants with Paris green or arsenate of
lead is effective against cutworms and safe for most vegetables, but
not for lettuce.

It is often easier to pick, brush, or shake off cutworms than to
destroy them by poison.

In agricultural practice, early fall-plowing is often helpful if
done while cutworms are still actively feeding. Their food being
thus destroyed, many will starve, and others will be too weak to
survive the winter. On the other hand, if the plowing is delayed
until the cutworms have pupated, little or no benefit will follow.
Crop rotation may sometimes be useful, but as very few garden
plants are unmolested by cutworms, it is not to be relied on. Nev-
ertheless, if it can be avoided, the more succulent plants should not
be grown in soil known to be infested by cutworms.

Clean culture is, of course, important. Weeds and rubbish af-
ford excellent breeding places for cutworms as well as for many
other insects.

THE LETTUCE PLANT-LOUSE
Macrosiphum lactuce Walt.
(Nectarophora lactuce, Siphonophora lactuce, Aphis lactuce)

The lettuce-louse is probably to be found in every Illinois green-
house where lettuce is grown. It often becomes very abundant,
especially in the lettuce heads, and not only stunts the plants, but
makes the product unsalable because it is impossible to free the
heads thoroly from the lice. I have also found this louse on celery
out-of-doors, but never sufficiently abundant to do injury.

Its life history is the same as that of most other plant-lice; that
is, the viviparous female reproduces without the intervention of the
male, and gives birth to living young. Each louse may produce 50
to 100 young, and because of this great reproductive capacity a
greenhouse may be almost overrun before the presence of the in-
sects has been noticed.

Natural Enemies.—Fortunately, this species, like most plant-
lice, is subject to the attacks of many parasitic and predaceous in-
sects which do much to control it. They are seldom capable of

133

holding it completely in check, however, and remedial measures
must be resorted to.

Remedies.—Only remedies to be used in greenhouses need be
mentioned, as this louse has not been found by us of economic im-
portance elsewhere.

Fumigation is the only satisfactory remedy. The lice are
usually within the heads, making it almost impossible to reach them
with a spray; and at any rate the use of an effective spray would
probably spoil the lettuce for the market. Tobacco or one of the
tobacco extracts, or, better, hydrocyanic acid gas, may be used as
a fumigant. The latter is the more effective, and will also destroy
the white-fly and the aphis of the cucumber, which plant is usually
grown in the same houses with lettuce. (See pages 156 and 159.)

Tue [mMporTED CABBAGE-WORM
Pontia rape Linn.
(Pieris rape)

Occasionally the cabbage-worm becomes abundant and destruc-
tive to greenhouse lettuce, and I have seen beds which were planted
the last part of August or the first part of September completely
ruined by it. It has been already sufficiently discussed as one of
the cabbage insects (pages 104-107).

Methods of Control.—As arsenicals can not be used on lettuce,
it is hardly probable that the cabbage-worm in greenhouses can be
successfully treated by any of the measures advised for its con-
trol out-of-doors (pages 106-107). If there are cabbage gardens
near a greenhouse, it is not advisable to plant lettuce until the mid-
dle or last of September. If, in spite of precautions, a bed becomes
badly infested, the plants should be thoroly sprayed with Paris
green, and pulled up within two or three days, after which the
bed may be replanted.

ONION

With the possible exception of the potato, the onion is the most
important’ garden product of Illinois and its insect enemies are
the most difficult to control. In 1899, 2,563 acres were used for
the growing of onions in this state, and the acreage has enormously
increased since then. ‘There are but two onion pests which are of
general economic interest, the onion-maggot and the onion thrips.

THE ONION-MAGGOT
Phorbia ceparum Meigen
(Pegomyia cepetorum, P. ceparum, Anthomyia ceparum)

Any one who has ever had anything to do with onion-growing
is fully aware of the great damage done by the onion-maggot (Fig.

134

26). As soon as the plant begins to sprout, the work of the maggot
begins, and it is at this time that much of the damage is done, altho
it 1s not so evident then as later. Much of the trouble attributed
to poor seed is really due to the maggot, which may attack and
quickly kill the plants just as they appear above ground, or even
sooner. The earlier the attack the greater the number of plants
destroyed, since more will be eaten by the maggot.

Fig. 24. Onion-maggot, Phorbia ceparum, female and head of
male. Length of, body about three-sixteenths of an inch.

The adult (Fig. 24) of this maggot is very similar to the com-
mon house-fly in general appearance, except that it has a grayish
thorax and is somewhat smaller. It is a near relative of the cab-
bage root-maggot, already described, and the two insects, as well
as their work, are much alike. The winter may be passed in any
one of its various stages excepting the egg. Hibernating adults,
or adults maturing early in spring, deposit eggs deep in the cracks
and crevices of the earth, near the young plants. The minute mag-
gots hatching two to four days later, more or less according to the
prevailing temperatures, make their way to the bulb and begin
feeding on the roots and the underground parts of the plant. They
burrow within the bulb, causing the inner parts to decay. An in-
fested onion may appear sound, but by pressure the rotten parts
and the maggots may be forced out. When full grown, some two
or three weeks after hatching, the maggots change to brownish

i=

135

oval puparia (Fig. 25) in the bulbs or in the earth not far from
the onions in which they have been feeding. These puparia trans-

Fig. 25. Onion-maggot, Phorbia ceparum, puparium. Length
about one-fourth inch.

form to adult flies in about two weeks, and the flies, in turn, de-
posit eggs for a second generation.

Fig. 26. Onion-maggot, Phorbia ceparum, larva, side view.
Length of body about five-sixteenths of an inch.

Fig. 27. Onion-maggot, Phorbia ceparum, tip of larva, top and
side views. Greatly magnihed.

Natural Enemics.—The onion-maggot has a few parasitic ene-
mies, but they are seldom numerous enough to hold it in check,
and have little economic value in Illinois. Chickens and other
domestic fowls are fond of this insect, but on a large onion farm,
it would be too difficult and expensive to keep enough of them to
be of much assistance.

Methods of Control.—As this insect often lives over the winter
as a maggot or as a puparium in the onion bulb, it is of great im-
portance that the fields should be thoroly cleaned up in fall, no
onions being allowed to remain there over winter.

As a rule, this pest is more abundant and destructive on com-
paratively sheltered areas than in open fields over which the winds

186

have full play. This fact should be borne in mind in locating onion
beds.

The amount and kinds of manure used may have an important
influence on the damage done by this insect. Prof. C. G. Hewitt,
of the University of Manchester, England, has recently shown*
that Anthomyia radicum, a European species very closely related to
the onion-maggot, breeds freely in horse manure. It has often been
noticed by entomologists and gardeners that fields which have been
abundantly manured are worse infested than those where little ma-
nure has been used.+

It is much easier to keep these maggots from infesting onions
than to kill them after their appearance. The three best repellents
and preventives which have been recommended from time to time
are hellebore, tobacco dust, and dry lime. The first two are dis-
cussed under remedies for the cabbage root-maggot, (pages 109 and
110) and on pages 154 and 155. Dry lime may be applied in the
same manner as tobacco dust. These substances either repel the
fly or prevent the maggot from reaching the plant even tho the
eggs are deposited. They should be applied about the time the
plants are sprouting or just as they appear above ground.

After plants have become infested it is often possible to kill
the maggots before they enter the bulb by applying a contact in-
secticide. Carbolic acid emulsion and a decoction of hellebore
(pages 153, 154) have given the best results. They should be ap-
plied as soon as the maggots are noticed, or at least before they
enter the bulbs, otherwise it is impossible to reach them with any
insecticide.

Old onions may be used as traps for the maggots by placing
them along the edges of the field in small piles in early spring,
before the onion seed has been planted. The flies will be attracted
to these decaying onions, which should be destroyed after infes-
tation, particular care being taken to do this before any of the
maggots have become adults.

Mr. F. A. Sirrinet suggests the following hand method: ‘‘To
get at the onion-maggot after the eggs have been laid, carefully
lift all the infested onions and destroy the maggots by crushing
or by dipping in kerosene. If this is done early in the season,
when their work is first noticed, it will be no more of a task than
the process of first weeding.”

*On the Life-history of the Root Maggot, Anthomyia radicum, Meigen.
Jour. Econom. Biol., Vol. II, Pt. 2 (Aug. 31, 1907), p. 57; and On the Bionom-
ics of certain Calyptrate Muscide and their Economic Significance, with es-
pecial Reference to Flies inhabiting Houses. Ibid, Pt. 3 (Dec. I1, 1907),
pp. 86-87.

For tests with “blood and bone” see page III.

¢+Maggots and Smut in Onions. Rural New Yorker, May 12, 1900, Vol. 59,
Pp. 334.

137

he use of commercial fertilizers, to force the plants rapidly
at first, will greatly lessen the amount of injury by the maggot.

THE ONION THRIPS
Thrips tabaci Lind.

In July or August one sometimes sees whitened onion plants
in numbers sufficient to give the entire field a hoary look. This
“white blast,” as it is often called, is due to a tiny winged insect,
the thrips of the onion, sometimes incorrectly called the “onion-
louse,’ which often appears in great numbers, feeding first at the
axils Of the leaves. It does not actually eat the leaves, for its

JR pS) b
SS J B/) LLL,
TIE.
eZ SASL ES \S
TT ss NI
HN EAN SM
Oe (as
Wa Bs: td

Fig. 28. Onion Thrips, Thrips tabaci: a, adult; b, antenna of
same; c, young larva; d, full-grown larva. All highly
magnified.

mouth parts, which form an inverted cone projecting from the
under side of the head, are not of the true biting type. It pierces
the epidermis of the leaf, and by moving the tip of the cone back-
ward and forward it makes an opening, thru which it sucks the
juices of the plant. Since this thrips is a general feeder, attacking
many cultivated plants as well as weeds, it is of great economic
importance, not only to the truck gardener but to the florist also.
It is often injurious to cabbage and to cucumber plants in green-
houses.

Its eggs are deposited just within the leaf tissue. ‘The young
(Fig. 28, c) are very minute at hatching, elongate, and pale yellow-
ish. The adults (Fig. 28, a) closely resemble the young in shape,
but differ by their darker color, and usually by the possession of
wings. There are several generations a year, the number varying
according to the season. The winter is passed in either the larval
or the adult stage.

Natural Checks.—The insect enemies of this thrips are of no
importance, but the character of the weather has a noticeable in-
fluence on its abundance, wet weather being decidedly to its dis-
advantage. oy

Remedial Measures.—The standard insecticides for thrips are
kerosene emulsion and whale-oil soap. Spraying must begin at the
first appearance of the insects, and must be repeated in a week or
ten days. The most effective indoor remedies are thoro and fre-

138

quent fumigation with tobacco and tobacco extracts, or with hydro-
cyanic acid gas.

Clean culture is very important, since thrips hibernate on weeds
and grasses along the edge of the onion fields. By plowing up all
weedy and grassy land late in fall, after the thrips have left the
onions, or by thoroly burning over such land during the winter,
the number of thrips can be greatly diminished. Entire com-
munities should practice these farming methods, for otherwise
fields properly cared for may become reinfested from those
neglected.

GARDEN “PEAS

Garden peas are grown to a considerable extent by many of
the market gardeners, and one insect pest, the pea-louse, has been
found to do great injury to this crop in Illinois.

THE PEA-LOUSE
Macrosiphum pist Walt.
(Nectarophora destructor, Siphonophora pisi, Aplus pist)

This plant-louse (lig. 29) 1s common in all parts of the United
States, and is a pest of some importance in Europe, its original

Fig. 29. Pea-louse, Macrosiphum pisi, on stems of red clover.
Natural size.

139

home. Its life history is not unlike that of plant-lice already de-
scribed. The adult is about the size of a pin-head, or a little larger,

Fig. 30. Pea-louse, Macrosiphum. pisi, winged viviparous female.
Greatly magnified.

pale green, and soft. It may be winged (Fig. 30) or wingless
(Fig. 31). The winter is passed either in the egg or the adult
stage, and usually on clover, from which it migrates to the pea in
spring, sometimes multiplying enormously on this crop.

Fig 31. Pea-louse, Macrosiphum pist, wingless viviparous female.
Greatly magnified.

Natural Enemies.—Many parasitic and predaceous insects prey
on the pea-louse and materially aid in checking its rapid multipli-
cation, the parasites not infrequently becoming numerous enough
to control it completely. (Fig. 32.)

140

Fig. 32. Pea-louse, Macrosiphum pisi, empty skin after the
emergence of a winged parasite. Greatly magnified.

Fig. 33. Pea-louse, Macrosiphum pist, attacked by fungus.
Greatly magnified.

Remedial Measures.—Sprays of kerosene emulsion or whale-
oil soap solution are probably the best remedies known. They
should be applied at the first appearance of the lice, and continued
as needed.

The brush and cultivator method is also much used. With this
in view the peas must be planted in rows at least two feet apart.
As soon as the lice infest the vines, and at intervals subsequently.
they are brushed from the vines and covered by a cultivator before
they can get back. Brooms made of fresh-cut pine branches have
been suggested for brushing the lice from the vines.

POTATO

The potato is the most important vegetable grown in Illinois,
both in acreage and value of the crop. Tho it is attacked by a

141

number of insect pests, none are of much economic importance in
this state except the Colorado potato-beetle, the wireworms, the
flea-beetles, and the potato plant-louse. The stalk-borer (Papai-
pema nitela) is also occasionally injurious to this crop. For a dis-
cussion of this insect see pages 147-148.

THE COLORADO POTATO-BEETLE
Leptinotarsa 1o-lineata Say
(Doryphora ro-lineata)

This common and injurious species has doubtless caused greater
damage to potatoes in Illinois than any other insect, and it is found
on the vines in destructive numbers every year. It is a western
species, its original habitat being the Rocky Mountain region. Its
native food consisted of wild plants closely related to the potato,
and when potato-culture reached its native prairies it promptly
availed itself of the increased food supply thus afforded. It began
its migration eastward, by way of the potato fields, about the year
1860, reaching Illinois some fifteen years later. Except in the
Pacific coast region, it is now found generally distributed thruout
the United States and Canada, wherever the potato is grown.

e

Fig. 34. Potato-beetle, Leptinotarsa to-lineata: a, a, eggs; 0, larve,
young and full-grown; c, pupa; d, adults; e, wing-cover of
adult; f, hind leg of adult. Natural size except

@ and 7.

The yellow and black striped beetle (Fig. 34, d, d) passes the
winter in the ground, and makes its appearance early in spring. It
feeds at first on the young potato plants if these are at once avail-
able, or, if not, on some one of its wild food-plants. The sexes soon

142

mate, and the clusters of bright yellowish-orange eggs (Fig. 34,
a, a) are deposited on the under side of the leaves. Each cluster may
contain from 25 to 75 eggs, or even more, and individual beetles
have been known to lay as many as 3,000 eggs under certain arti-
ficial conditions. The average number, however, is about 450.* The
fleshy, grub-like larvee (Fig. 34, b, b, b) hatch in four to seven days
and at once begin to eat the potato leaves. They are dark red when
hatched, but gradually become paler as they grow, with two rows of
blackish spots along each side of the body. When two or three weeks
old they go into the ground for pupation, emerging as beetles one
or two weeks later. These beetles may feed and then go into hiber-
nation, or eggs may be deposited for another generation. The num-
ber of generations is still in dispute, but there is probably but one as
a rule, only a few of the beetles first to emerge laying eggs for a
second generation the same year.

Natural Enemies.—Insect enemies of the potato-beetle are not
uncommon, but it is doubtful if in Illinois they ever play any consid-
erable role in reducing its numbers. Its commonest parasite in the
vicinity of Chicago was a Tachina fly—Phorocera rufilabris V. d.
W.+t The white eggs of this fly were common on the backs of both
beetles and larvee—on the thoracic plate of the adult, and between
the thoracic segments of the larva. The maggots hatching from
these eggs enter the bodies of the beetles or the larve, soon killing
them. Many predaceous enemies are known, including soldier-bugs,
robber-flies, spiders, ground-beetles, ladybirds, tiger-beetles, rove-
beetles, and some native birds and the domestic fowls.

Methods of Control.—The two standard remedies for injuries by
this pest are Paris green and arsenate of lead. In Illinois, dry Paris
green, with or without lime or flour, is used by nearly all potato
growers. It has the advantage of being easy to prepare and apply,
but there are offsetting disadvantages which make it less desirable
than Paris green in water. It is less adhesive than the fluid spray,
and hence must be applied more frequently, and more labor is re-
quired. The dry poison is very injurious when breathed into the
lungs by the person applying it. Bordeaux mixture should always
be added to Paris green when it is applied in water—as also to the
arsenate of lead—for this compound spray is more effective against
flea-beetles, and is a remedy for blight. Furthermore, the lime in
the Bordeaux unites with the Paris green, thus increasing its adhe-
siveness, and it changes the soluble arsenic to insoluble, thus pre-
venting the burning of the foliage which often follows when Paris
green is used alone. The method of preparation is:given on pages

*Further Biological Notes on the Colorado Potato-beetle, Leptinotarsa
decemlineata (Say), by Alec. Arséne Girault. Annals Ent. Soc. America,
Vol. I, No. 2 (June, 1908), p. 158. Columbus, Ohio.

*Determined by C. A. Hart.

143

£51-153. The potato patch, and indeed the entire farm, should be
kept free from weeds of the nightshade family, for the potato-
beetle can breed on these.

\WIREWORMS
Limontus confusus Lec.

But one kind of wireworm has been found by us common enough
in Cook county to require special mention, but this single species is
very injurious there to potatoes (Fig. 35, 26), radishes, onions, tur-
nips, tomatoes, cabbage, corn, and horseradish. It burrows into or

Fig. 35. Potatoes showing injury by wireworms, Limonius con-
JusUs.

devours the roots and tubers of these vegetables, thus often com-
pletely ruining the crop. With the exception of the onion, tomatoes,
cabbage, and corn, the plants above mentioned give no evidence
above ground of the presence of wireworms, their attacks seldom
weakening the plant, but merely disfiguring the marketable part.

Fig. 36. Wireworm, Limonius confusus, larva.
Length about three-fourths inch.

Bien 37. 1 dip on elatva:
seen from above.
Greatly magnified.

144

Remedial Measures.—Three methods of control are practiced:
rotation of crops, fall plowing, and poisoned baits. Cropping for
two years with some vegetable which is virtually immune, such as
beans, peas, spinach, cucumber, melon, rhubarb, lettuce, or pepper,
should rid the soil of wireworms.*

Fig. 38. Wireworm, Limonius confusus, adult beetle. Length
about three-sixteenths inch.

Late summer or fall plowing is frequently resorted to in order
to destroy the pupze and beetles. The land should be cultivated thor-
oly several times in the fall.

Trapping the adults by poisoned baits is a method sometimes used
in the eastern states. Sliced potatoes, wads of green clover, or corn-
meal dough, poisoned with Paris green, have been found effective.t
These baits should be placed under boards in various parts of
the field, and renewed once or twice a week during the spring and
early summer.

*This list is given on the authority of those who have reported these plants
to be practically uninjured by wireworms, even when the latter are present in the
soil.

+Our own experiments the past year with poisoned baits for this insect
were not sufficiently effective to pay for the labor and materials.

145

THE PoTATO FLEA-BEETLE
Epitrix cucumeris Harr.
(Crepiododera cucumeris Harr.)

Potato leaves are often riddled with small holes as if they had
been the target for a discharge of shot. Such injury is the work of
flea-beetles. The life history and habits of the potato flea-beetle

Fig. 39. Potato Flea-beetle, Epitrix cucumeris, adult. Enlarged
as indicated.

(Fig. 39) are essentially the same as those of the cabbage flea-beetle,
which is discussed on pages 113-114.

Remedies.—The best remedy is spraying with Paris green, or
arsenate of lead, and Bordeaux mixture, as recommended for the
potato-beetle (page 142). Potatoes may be thus protected against
the potato-beetle, the flea-beetle, and the blight. Other remedies
applicable to this pest may be found on page 114.

THE PoTaTo PLANT-LOUSE
Macrosiphum solanifolii Ashm.
(Nectarophora solanifolii, Siphonophora solanifolti)

The potato plant-louse is often a very troublesome species,
densely infesting the tops of the plants and soon stunting or even kill-
ing them. It is so much like the notorious and destructive pea-louse
that the two species can not be distinguished without a closer exam-
ination than the ordinary observer is likely to make. Altho com-
monly pale greenish, there is a red variety of this species which, dur-
ing the summer, is often as abundant as the commoner green form.
The life history and natural enemies of this aphis are similar to
those of other plant-lice already described.

Remedial Measures—The only available remedies are those
suggested for other plant-lice; namely, kerosene emulsion and soap
solutions (page 153).

146

Clean culture seems to be of much importance, inasmuch as the
eggs are deposited in fall on shepherd’s-purse and possibly on various
other weeds.*

Fall plowing and burning over grassy and weedy areas in the
neighborhood of potato fields are certainly to be recommended; and
Miss Patch further commends, as a precaution, the practice of burn-
ing old potato stalks, since belated specimens of the plant-lice may
possibly remain on them under certain conditions.

S PEN AC Et

Spinach is often attacked in fall by a plant-louse which some-
times destroys entire fields.

THE OMNIvoROUS PLANT-LOUSE
Myzus persica Sulz.
(Rhopalosiphum dianthi, Aphis dianthi) —

In the fall of 1908 my attention was attracted to the great abun-
dance of a plant-louse infesting spinach on many truck-farms near
Chicago. This louse may feed on almost any plant, as the common
name above given implies. Among the vegetables which it sometimes
injures, weakening the plants and causing a curling of the leaves, are
turnip, radish, celery, cabbage, and cauliflower. It is impracticable
to wash off these green lice after they become abundant, and the
presence of thousands of them on the spinach renders it unsalable.

Remedies.—The only practicable remedy is thoro spraying with
a contact insecticide which will not give a permanent odor or taste
to the leaves. The standard tobacco or nicotine extracts (page 154)
answer the purpose. It is very important that spinach should be
closely watched, and that the plants be sprayed at the first appear-
ance of the lice. The treatment should be repeated at intervals as
may be necessary.

TOMATO

Altho not extensively grown in the truck gardens of Cook county
the tomato is of much importance in other parts of the state, partic-
ularly as supplied to canneries. A stalk-borer (Papaipema mitela) is
the principal insect enemy of the crop in Cook county, and is no
doubt the cause of more damage than is commonly charged to it. To
the casual observer there is no indication of the presence of this in-
sect when the plants wilt and die from its attack, and as a rule the
gardener is at a loss to find the cause, the characteristic round hole
in the stalk being easily overlooked. Occasionally the Colorado

*According to Miss Edith M. Patch. See “The Potato Plant Louse.” Bull.
Maine Agr. Exper. Station, No. 147 (Nov., 1907), pp. 247-248. Orono, Me.

147

potato-beetle, treated on pages 141-143, damages tomatoes soon
after transplanting to the field.

THE STALK-BORER
Papaipema nitela Guen.
(Hydrecia nitela, Gortyna nitela)

This borer, or “heart worm,” as it is often called by corn grow-
ers, was found destructive to tomato and corn, and occasionally to
potato, in a number of restricted areas during the past year. Other
vegetables known to be injured by it are rhubarb, spinach, cauliflower,
eggplant, and pepper.

The presence of this caterpillar in the tomato plant is indicated
by the wilting or death and final breaking down of the top, and by
the presence of a round hole in the side of the stalk, from which a

Fig. 40. Stalk-borer, Papaipema nitela: a, adult; b, half-grown
larva; c, mature larva in burrow ; d, side of one of its
segments; ¢, pupa. Slightly enlarged.

brownish excrement is oozing. Upon careful examination of plants
so injured a peculiarly striped larva (Fig. 40, b) will usually be
found in the stalk. The following description is quoted from Pro-
fessor Forbes.*

The larva may be readily recognized “by the peculiar break in
the striping of the body at the middle * * * [Fig. 40, 6] giv-
ing it an appearance as if it had been pinched or injured there. It is

*Twenty-third Rep. State Ent. IIl., pp. 44, 45.

148

about an inch long when full grown. The general color varies from
purplish brown to whitish brown, according to age, and it is marked
with five white stripes, one running down the middle of the back,
and two on each-side * * *, The stripes nearly vanish as the
larva matures [Fig. 40, c]. The head and top of the neck, and the
leathery anal shield at the opposite end of the body are light reddish
yellow with a black stripe on each side.”’

The young caterpillar first feeds within the stems of grasses or
weeds, but as it becomes larger it is compelled to seek thicker-
stemmed plants, and it is at this time that it begins to infest garden
vegetables. In northern Illinois, in 1908, half-grown larve were
found in tomato stalks the middle of June, when fully half the plants
in the field had been killed by.them. The larva usually enters the
stem near the base and burrows upwards. When full grown it
changes into a reddish brown pupa (Fig. 40, e) within the stalk,
usually below the original entrance-hole, and later the grayish moth
(Fig. 40, a) emerges. According to Prof. F. L. Washburn * the
eggs of this moth are deposited in masses on the stem of the plant
near its base. It is supposed that they are laid in grass lands in fall,
and that they hatch the same season or the following spring.

Economic Procedure.—After plants have become infested, no
remedy can be used to save-those individual plants, and they should
be pulled up and burned immediately to prevent the larve from en-
tering other plants, and also to decrease the number of the borers
for the next year.

In spring, vegetation around tomato, potato, and corn fields
should be watched, and if it is wilting or dying it should be exam-
ined to learn if this borer is present, in which case the weeds should
be cut and destroyed without delay.

Late fall-plowing of infested fields is advised in order to bury
the eggs, which, as already said, are supposed to be laid in grass or
weedy land in fall, and all weeds, not only in the fields but along
the roadsides adjoining them, should be destroyed at this time.

PREPARATION OF INSECTICIDES FOR Use AGAINST INSECTS
Insurtous TO GARDEN AND HorHousE VEGETABLES

From the economic point of view insects are divisible into two
classes; those which chew and swallow the tissues of the plant, and
those which suck their juices. Insects of the first class—cabbage-
worms, potato-beetles, and cutworms, for example—can usually be
destroyed by one of the so-called stomach poisons listed on page
149; but those of the second class—plant-lice, thrips, the white-fly,

*Preliminary Report upon Work with the Stalk Borers in Minnesota. 12th Rep.
State Ent. Minn., p. 151. Dec., 1908

<M

149

etc.—are unharmed by such insecticides because they take their food
from the interior of the plant, and so a contact insecticide must be
used.

The classification in the following synoptical list of insecticides
is based on their most obvious distinctions, and the subsequent treat-
ment corresponds to the order of the list.

Dust or Liquid Sprays.

Page
Stomach poisons for biting insects.
Paris green, dry, with or without an adulterant...... 149
fuse EORIT BICC SGI oh: ob es. aoter ths os ee ae ee 150
J NOP SCIELO VN Es La 4 IA eae agate a Meee bares Ay 150
heen iitie “mit xtite, with a poison. <%. 22.0. ye ks a 150
Boreas Mixture. with a poison (ks £8.25 es ig

Contact insecticides—for sucking insects.

MeaecccmemiulsiOn 2. o's oe pa hd) eae eee 153
Nitale-ou soap SOlWtON 2243s esa e-o ees oe se 153
npmicnd Cicmretit SION: 3% ch. r 2. ine eee ae yak ae
feletleWoiess CECOCHON .! a7 S oaeeat= suas, Os ee ee 154
iniseer powaer (pyrenuium or pulmach) 7. > 02.0... +5 - 154
Tobacco decoction and nicotine preparations ........ 154

58

Boye copia ew AcWersh ear etr. aL ca Ss res. we. oe aT

Poisoned Baits—for biting insects.

is OuempnGdMonsas Mima ae erga eran oc ws ola ene ei 155
EGinomeduiciicerom Clovereavesma .. 6. Aj. e 155

Repellents—for any insects.

Canoe ACI AMG Me das... Ee nee Lee oe 155
Ty GOSS GCOANCHIST EIS 2 Page (Oe tec ge 155
IL IAPS Ge i eo a ee aE 156
SOU SFE S Saath 9 ONT OMAP hy 5 aan ee ei erat 152
Fumigants—for any insects.
frleliuGyanier ACI FAS oC ere. we Bas coking eiee Syn eee 156
RGIS)“ DISILT| Saeea eiaernP ee eene eae ernie 158
See SUITE REE aR oN etter mete tn Str eae aU aa ee oR 159
OMe ieee SUIS) 2 a8 Siig e was s ehsictels ou a Spee eaters 159
Icomine PHCPATALIONS 9,022). ses «os sas owes gs aye Se 159

Paris GREEN—Dry

Unmixed Paris green may be sprinkled upon plants, but the dan-
ger of burning the leaves is lessened by adulterating it with flour,

150

land-plaster, or air-slaked lime in the proportion of one pound of
the poison to twenty-five pounds of flour or to fifty pounds of land-
plaster or lime.

Apply thoroly and evenly with a hand “‘dust-sprayer” early in
the morning, when the dew is on the plants.

Paris GREEN—LIQUID SPRAY

Formula

Paris et eene sire te cea nyse eae ee eee I pound
Wrastakede limes 4.940.627. se ce. nce cet ameee 1% pounds
WVCILEE 0: cnet ens Rha anata Cen aoe 150 gallons

Slake the lime and add the Paris green, thoroly mixing before
adding the water. The mixture must be kept well stirred while it is
being sprayed, and most spray-pumps have an attachment for this
purpose. The liquid spray is safer and more efficient than either of
the dry mixtures previously mentioned.

ARSENATE OF LEAD

Arsenate of lead can be made by properly combining lead acetate
and arsenate of soda, but it is difficult to make a good grade of it,
and unless large quantities are needed it is best to purchase standard
brands, which are ready for use when dissolved in water.

Tehe price of arsenate of lead is less than that of Paris green, but
as one must use two to three times as much of it to secure a desired
result, it is slightly more expensive as an insecticide than Paris
green. This fact is offset, however, by the following advantages
which arsenate of lead has over all other arsenicals: it is much more
adhesive, remaining on the foliage for a period during which two or
three sprayings with Paris green would be necessary; it remains in
suspension better; it shows on the foliage; and it is harmless to vege-
tation, this last fact being of special advantage when the more ten-
der plants are sprayed.

Care should be taken to obtain a good grade, for there are many
worthless brands on the market. Usually a good grade can be ob-
tained from any reliable wholesale druggist. As the strengths of
the various brands differ, the gardener should follow the directions
accompanying the arsenate he is to use.

RESIN-LIME MIXTURE

The resin-lime mixture serves as a stock solution to which poi-
sons may be added. It is valuable chiefly because of its adhesive
properties, being for this reason well suited to smooth leaves, such
as those of the cabbage. It has the disadvantage, however, that con-
siderable time is necessary for its preparation, and that it is especially
liable to clog the spray-nozzle. It is prepared as follows.

151

Stock Solution

PAI ENIZCC. TESIN Wtkaes nk a Hes ae eS eceptee ok 5 pounds
Wonteeminated lye, tee 5 4 Bec). hoes eee Ser I pound
Fish oil, or any animal oil except tallow ..1 pint

Din PRC MmMIRCe a betas creo she vors os eerie a 5 gallons

Place the resin, oil, and a gallon of hot water in an iron kettle
and heat until the resin is softened, after which the lye should be
added to the heated mixture and the whole thoroly stirred. Then
add the remaining four gallons of water and boil for about two
hours, or until it will unite with cold water and make a clear, amber-
colored liquid. If there is less than five gallons of the preparation,
add water enough to make that quantity. This stock solution will
keep indefinitely, and the quantity needed for the whole season may
be made up at one time.

Preparation for Use

SOG eS OMMMIGHAMER. s-Sc)s) <). nscesetit sae nen % t gallon
NI MISUCES Gig yeccek Jat dee aa eh A 16 gallons
MESES Soin a it 22" a a iL ar ane Ae, 2 gallons
SIS OMRON ecg acne! Hind apc tre) hee et eckbe eae Y% pound

First add the water to the stock solution, mixing thoroly; then
add the milk of lime; and, finally, add the Paris green, previously
stirred up with water to form a thin paste. The whole mixture must
then be thoroly stirred. This preparation should be made up as
needed, for if allowed to stand any considerable time it will settle,
and will also gum up the pump valves and the nozzles.

BORDEAUX MIXTURE AND PARIS GREEN

Bordeaux mixture is primarily a fungicide; but it is also useful
as a repellent against some insects, and with Paris green or arsenate
of lead it makes an excellent combination spray to be used when both
fungi and leaf-eating insects are to be dealt with on the same crop.

Various strengths of the Bordeaux are used by the vegetable gar-
dener according to the plants to be sprayed. Those in commonest use
are often conveniently designated as 4-4-50, and 6-6-50. The sig-
nificance of the figures is evident from the following 4-4-50
formula:

Sanmemesulpiate. sent sf seas Saha 4 pounds
NSTC CG Si oa ese te eae Die ec ee Prag 4 pounds
‘ys SGPETE 5 gigas sR ecg aT cc ea arte ae 50 gallons

For such plants as asparagus, tomatoes, and melons, the 4-4-50
strength is used; and for the potato and related plants, the 6-6-50.

*Milk of lime is made by slaking stone lime and adding sufficient water to
make a thin whitewash.

152

To make the Bordeaux mixture, dissolve the copper sulphate in
about 20 gallons of water—best done by placing the sulphate, or
bluestone, as it is often called, in a gunny sack or other stout cloth
bag and suspending it in the water. It will dissolve ina day or so,
and if covered to prevent evaporation it will keep indefinitely. If less
than 50 gallons of the Bordeaux mixture is needed, or if the solu-
tion is wanted immediately, the bluestone may be readily dissolved
in hot water.t In another vessel slake the lime, adding the water
slowly, to obtain a smooth, creamy liquid, using barely enough wa-
ter to cover the lime after it has settled. In this condition, if evap-
oration is prevented, it will, like the copper-sulphate solution, keep
indefinitely.

When ready to spray add enough water to each stock solution,
separately, to make 25 gallons, stir each thoroly, and then mix the
two together. This may be done by having the barrels containing
the two solutions on a high support, with plugs near the bottom so
that both solutions can be run into a third vessel below, the operator
stirring the fluids as they unite. Or, if such an apparatus is not ob-
tainable, the mixture may be made by pouring the two fluids to-
gether from buckets (Fig. 41).

Fig. 41. Method of preparing Bordeaux mixture by hand.
(Missouri Experiment Station.)

For the combined fungicide and insecticide, add five or six ounces
of Paris green, previously made into a paste with water, to fifty gal-

*Copper sulphate, either dry or in solution, corrodes iron, and a wooden,
earthen, brass, or copper vessel should be used.

153

lons of Bordeaux mixture, and thoroly stir. If arsenate of lead is
used in place of the Paris green, about four or five times as much
will be required.

Altho the separate solutions of the copper sulphate and of the
lime are stable, they are not so when combined, and therefore only
the quantity to be used at the time should be made up.

ICXEROSENE EMULSION
Stock Solution (66 percent kerosene)

SCODNL) © ORS Re A a Y% pound
EIR ESS ETE = 2a Se SRE are pam Cen 2 gallons
“IULINDIE Ee a a 1 gallon

If hard soap is used, cut it into fine shavings and dissolve in boil-
ing water, after which remove from the fire and immediately add
the kerosene and thoroly mix. This may be done most easily by
churning for about ten minutes with a force-pump, the nozzle being
turned back into the liquid; or, in the absence of a pump, the liquid
may be turned from one bucket to another for fully ten minutes,
holding the bucket high so as to give force to the falling liquid.
When thoroly emulsified it will have the consistency of thick cream,
and the oil will not separate out. There is great danger of injuring
the plants if the mixture is not well and thoroly made.

For spraying vegetation the stock solution should be diluted to
the desired strength. For a five percent emulsion add 37 gallons of
water to 39 gallons of the stock solution; for a 10 percent emulsion
add 17 gallons of water to the same; and for fifteen percent emul-
sion add 10% gallons.

It is desirable to use soft water both for the stock and as a dilu-
ent, but if this is not obtainable the water should be softened by add-
ing lye or sal-soda.

The emulsion should be applied to plants with a spray-pump, and
in a fine mistlike spray. For most insects a ten percent emulsion is
strong enough.

WHALE-OIL SOAP SOLUTION
Whale-oil soap is an effective insecticide for plant-lice and other

soft-bodied insects. For use, dissolve one pound of the soap in six
to eight gallons of hot water.

CARBOLIC ACID EMULSION
Carbolic acid emulsion is a contact insecticide, and also acts as a
repellent, being chiefly used for the treatment of root-infesting in-
sects.

*Either hard or soft soap may be used. Whale-oil soap and “Tak-a-nap”
soap have given excellent results.

154

Stock Solution

Hard soap (preferably “Ivory” or ‘““Tak-a-nap”) 1 pound
Olt AWahese arias & Sel nO ener... cee ae t gallon
Crudemeariolie acid, sol see a. 5 eee eee I pint

Dissolve finely shaved soap in boiling water, add the carbolic
acid, and churn as for kerosene emulsion. For use, one part of the
stock solution is diluted with thirty to forty parts of water.

HELLEBORE DECOCTION

For use against root-maggots, this decoction is prepared by steep-
ing two ounces of white hellebore in one gallon of hot water for 30
minutes. For insects infesting the foliage, one ounce of hellebore
to two gallons of water is sufficient. Hellebore very soon loses its
insecticidal properties by exposure to the air, and care should be
taken to obtain only such as is known to be fresh.

INSECT PowpDER (PYRETHRUM, OR BUHACH)

Pyrethrum, or insect powder, as this insecticide 1s commonly
called, is of special value for killing certain kinds of insects, and it
has the advantage of being harmless to human beings and the higher
animals. On the other hand, its expense prohibits its use on a com-
mercial scale, and it quickly loses its virtue when exposed to the air.
If used in a dry form it should be mixed with twice its weight of
common flour, and kept in a tightly closed vessel for 24 hours before
using. It may be applied with a dust sprayer or some sifting appa-
ratus. A decoction of pyrethrum may be made by mixing one ounce
of the powder with enough water to form a thin paste and allowing
it to stand several hours, after which sufficient water should be added
to make two gallons. This is less effective than the dry powder.

In purchasing pyrethrum, only hermetically sealed cans of it are
safe, for the reason already given, but if they can not be obtained
care must be taken to buy only an absolutely fresh article.

Tospacco DECOCTION AND NICOTINE PREPARATIONS

Tobacco decoction, altho not so effective as some of the above-
mentioned contact insecticides, is still used by many for killing soft-
bodied insects, such as plant-lice. It is prepared by steeping tobacco
stems in hot water at the rate of one pound to two to three gallons.

More reliable than the above are various commercial prepara-
tions which likewise have nicotine as their active principle. (See
page 159.)

155

LYE-SULPHUR WaAsH

This contact spray is said to have particular value against the
red spider. It is prepared by mixing five pounds of flowers of sul-
phur with cold water and then adding to this sulphur paste two and
a half pounds of pulverized caustic soda. Water is added from time
to time, to prevent burning, until a concentrated solution of five
gallons is obtained. One gallon of this stock solution is sufficient for
25 gallons of spray.

PoIsOoNED BRAN MasuH

OLD Coe 5 Soe Pe te ae nr 16 pounds
PAVED SEe Ocean a I pound

Slightly dampen the bran and add the Paris green, mixing until
every particle of the bran bears some of the poison. The bran should
be barely wet enough to make the powder adhere to it, as experi-
ments in greenhouses strongly indicate that a soggy mash is not
freely eaten by cutworms. A little salt in the water used is said to
give the mixture additional relish.

POISONED LETTUCE OR CLOVER LEAVES

Small lots of lettuce or clover are poisoned with Paris green,
either dry or suspended in water, and the poisoned vegetation is
then cut or mowed and scattered over the infested tract (see page
131). This and the poisoned bran mash seem to be about equally
effective.

CARBOLIC ACID AND LIME

A coating of the soil at the base of the plants with carbolic acid
and lime has been recommended by Dr. John B. Smith * as ‘“‘the most
effective material tested” in his experiments against the onion-mag-
got in New Jersey. To make the mixture, slake three pints of lump
lime in a gallon of water, and add one tablespoonful of crude carbolic
acid. When applied properly along the rows with a sprinkling-can
or spray-nozzle, a thin crust will form on the ground around the
plants, which is said to serve the same purpose as the tarred felt-
paper protectors described on page 110.

Tospacco Dust

Tobacco dust has been recommended as a useful repellent , par-
ticularly against such insects as root-maggots and cucumber-beetles.
It has the further advantage of serving as a contact insecticide and

*The Cabbage and Onion Maggots. Bull. N. J. Agr. Exper. Station, No. 200

(Feb. 12, 1907), pp. 16-19.
tFor reference to our own experience with it see page IIO.

156

as an excellent fertilizer. Indeed, it is said that its value as a fer-
tilizer alone is sufficient to cover its cost.

For leaf-eating insects it is dusted on the leaves early in the
morning, while the dew is on. For root-feeding insects it is sprink-
led along the rows at the base of the plants, preferably when the soil
is moist.

Dry LIME

Fresh air-slaked lime or quicklime when used as a repellent for
root-maggots is sprinkled along the rows close about the plants, and
acts similarly to the carbolized-lime application. As some insects of
economic importance are attracted to manures, the latter should be
sprinkled over with lime where there is danger of infestation by in-
SECT pests.

Dry lime, especially when fresh,-is strongly caustic, and is there-
fore valuable as a contact insecticide for slugs, plant-lice, and soft-
bodied insects generally.

HyprocyANic Acip GAs

Hydrocyanic acid gas is doubtless the most powerful and ef-
fective fumigant known. Indeed, many are afraid to handle the
deadly gas; but it can be used with perfect safety if proper care be
taken.

It is impossible to give a set formula for its use, owing to
differences in the structure of greenhouses. In those of average
tightness I have used it on cucumber plants, without injury to them,
at a strength of I ounce of potassium cyanide to 3,000 cubic feet of
space—fumigating in the evening, and keeping the house closed over
night.

The materials necessary for fumigation with hydrocyanic acid
gas are potassium cyanide (98 to 99 percent pure), commercial sul-
phuric acid, and water; and the requisite utensils are half-gallon or
gallon jars—stone, earthen, or granite—and a supply of ordinary
small paper bags.

Fig. 42. Diagram illustrating determination of cubic contents of -
greenhouse.

157

The number of cubic feet in the house should first be accurately
calculated. The method of doing this may be illustrated by a sim-
ple computation based on the dimensions given in the accompanying
figure, the understanding being that the length of the greenhouse
is 100 feet. (Fig. 42.) The cubic contents of the rectangular sec-
tion of the house, ac d e, equals 246 100—=14,400 cubic feet;
that of the triangular section a b x, equals 88x 100-—-2==3,200
cubic feet; and that of the other triangular section, b c x, equals
8 16 100--2—6,400 cubic feet. The cubic contents of this house
are, therefore, 14,400 + 3,200-+-6,400—24,000 cubic feet. Assum-
ing this house to be of no more than the average tightness, we may
safely use potassium cyanide at the rate of one ounce to every 3,000
cubic feet of space, and 24,000 divided by 3,000 gives 8 as the num-
ber of ounces required in this illustrative case.

The next procedure is to prepare the materials for use and to
place the jars in the house. For every ounce of the potassium cya-
nide used, two ounces of sulphuric acid and four ounces of water are
required. Two ounces of the cyanide is about the right quantity for
each jar, therefore, for a house of the above dimensions, four jars
should be placed at equal intervals along the aisles, and the eight
ounces of cyanide divided into four equal parts, and each part put
into one of the paper bags. These are used not only for convenience
in handling the cyanide when placing it in the jars, but also because
they slightly delay the action of the sulphuric acid upon it, thus giv-
ing the fumigator ample time to leave the house before the reaction
occurs. The jars being in place and the cyanide properly weighed
and bagged, the next step is to close all the ventilators in order to
prevent any avoidable escape of gas. The water—four liquid ounces
to every avoirdupois ounce of cyanide—is then placed in each jar,
the sulphuric acid—half as much as the water—is added, and as
soon after as possible the bags of cyanide should be put into the jars
and the house vacated immediately. Doors should be locked and
labels posted indicating the danger. No one should enter the house
until it has been thoroly aired by opening the side doors, and, if con-
venient, the ventilators also. It is best to fumigate in the evening,
keeping the house closed till morning. I have never found a green-
house so tight that the fumes would remain in it in dangerous quan-
tities all night; nevertheless, it is safest to air the house well before
entering.

Precautions and Miscellaneous Directions.—As cyanide of potas-
sium is a powerful poison it should be handled as little as possible.
It should be kept in tightly closed cans or jars, plainly labeled, where
it will be inaccessible to persons not acquainted with its poisonous
properties. Use only a grade 98 to 99 percent pure. It may be ob-
tained in either granulated or lump form, the former being the most
convenient for use in fumigation.

158

Sulphuric acid should not come in contact with the hands or with
the clothes, as it will severely burn the flesh and ruin the clothes. It
should not be placed in metal receptacles, as it will soon eat them
thru.

Fumigate in the cooler parts of the day, and avoid, if possible, a
temperature above 60° or 65° F., since at a higher temperature the
plants are more liable to be injured.

The foliage of plants to be fumigated should be perfectly dry,
otherwise it will absorb the gas and be burned.

The best-shaped jar, when using two ounces of cyanide to a jar
is one four or five inches in diameter and about nine inches high.
If more cyanide is to be used in each receptacle larger jars must be
used.

Always put the water into the jars first, adding the acid later.
Never pour water into the undiluted acid.

After placing the sulphuric acid in the jars the bags of cyanide
should be put in as soon as possible, for any delay will interfere with
the proper reaction of the chemicals owing to the fact that the acid
acts most powerfully when it first unites with the water. The manner
of putting the bags into the acid is also important. They should
not be held a foot or more above the jars and dropped in, as the
bags may be thrown out by the reaction. Each bag must be care-
fully laid in the jar, but the fumigator must not lean over the jar
as he does it, nor remain near it to watch the reaction. After a few
fumigations the operator often becomes less attentive to the pre-
scribed directions and precautions. This tendency should be
promptly checked, the utmost care and caution being uniformly nec-
essary.

CARBON BISULFID

Carbon bisulfid is used as a fumigant for aerial plant-lice, for
root-lice and root-maggots, and for weevils in seeds. For methods
to be followed in treating the first class mentioned, see page I12.
For root-lice and root-maggots, a small hole is made in the ground
near the plant, and into it is poured a small tablespoonful of the liq-
uid. The hole is then promptly closed and the maggots are killed by
the fumes. The carbon bisulfid should not be poured on the plant
above ground nor directly on the roots. For weevils, the seed should
be placed in a tight box or bin, space being left at the top for a pan
or other shallow dish for the carbon bisulfid. This should be used
at the rate of one ounce to 60 cubic feet of box space, and the box
should be kept closed for 24 hours. The vapor given off, being heav-
ier than air, descends, killing all insects present without injuring
the seed.

159

As the fluid is inflammable, and its vapor, mixed with air, some-
what explosive, precaution should be taken never to permit a spark
of fire to come in contact with it.

Carbon bisulfid may be obtained at drug stores for 20 to 35
cents a pound. A grade known as “Fuma Carbon Bisulphide,” which
is fully as effective for fumigation as the ordinary grade sold by
druggists, is manufactured by E. R. Taylor, Penn Yan, New York,
and furnished in 50- or 100-pound cans at 10 cents a pound.

SULPHUR

Thoro cleaning of greenhouses for the eradication of insect pests
should be practiced by the greenhouse gardener when the houses are
empty, and fumigating with sulphur is one of the best and easiest
means to this end. About one pound of sulphur should be burned
to every 2,000 cubic feet of space, after which the house should be
kept tightly closed for 24 hours, or longer if convenient. It is need-
less to say that at this strength all plants, as well as insects, will be
killed.

For fumigating houses containing growing plants, evaporate a
small quantity of sulphur in a suitable receptacle over a lamp or oil
burner, taking care that it does not catch fire; or the steam pipes may
be painted with a sulphur paste made by mixing sulphur and water.
A paste is sometimes made in which the sulphur is mixed with oil
instead of water. Sulphur is not only valuable as an insecticide, but
useful in controlling mildew.

TosBacco STEMS

Tho tobacco stems for fumigation purposes have been largely
superseded by the recent introduction of various nicotine extracts,
they are still used, and are recommended for killing plant-lice and
thrips, especially when easily obtainable at a reasonable price.

Three piles of stems, of about half a bushel each, are used to every
100 linear feet of the house, the piles being dampened to prevent
rapid burning. These are set on fire in the evening, when the build-
ing is left for the night. The house must be kept as tightly closed
as possible until morning. Frequent fumigations—at least weekly—
are necessary to obtain the best results.

NICOTINE PREPARATIONS

Many nicotine preparations are now on the market under such
trade names as “Nicoteen,’ ‘‘Nicoticide,” ‘“To-ba-ken,” ‘“Nico-
Fume,” etc. Most of them contain 25 to 45 percent of nicotine, and
are more effective, tho more costly, than tobacco stems or tobacco
dust. They may be used as fumigants in various ways. The com-

160

mercially prepared fumigating papers are suspended in strips and
lighted when ready to fumigate. Dry preparations are placed in
shallow dishes and ignited. It is sometimes advisable to add a few
drops of kerosene to facilitate their burning. The extracts are evap-
orated over a lamp, or, like the sulphur paste, are painted on the
steam pipes. They evaporate or burn slowly, producing a powerful
vapor. Asa rule it is best to fumigate in the evening, keeping the
houses closed over night. Most insect pests of the greenhouse may ~
be controlled by thoro and oft-repeated fumigations with one of these
extracts.

INDEX

A

acerni, Sesia, 35.

Agrilus anxius,
borer, Bronze.

Agrotis saucia, 107, 129.

Ailanthus, 60.

Alders injured by Poplar and Wil-
low Borer, 40.

Aleyvrodes vaporariorum, 121-123. See
Greenhouse White-fly.

alia, Taeniocampa, 77, 78-82.

Althea infested by San Jose Scale,
59.

Amarantus retroflexus as breeding
plant of Onion Thrips, 124.

Ammann, J. 1st 129.

ice ri “. a

53-55. See SBirch-

Arbor-vitae infested by
39.
by San Jose Seale, 60.
Archytes aterrima as parasite of Va-
riegated Cutworm, 131.
Arsenate of lead and Bordeaux mix-

ture for Cabbage Flea-
beetle, 114.
for Colorado Potato-bee-

Bag-worm,

tle, 142.
for Potato Flea-beetle,
145.

composition and compara-

tive cost and rank of, as
insecticide, 150.
for Bag-worm, 40.

ERRATA

Page 46, in legend for Fig. 51, for 7chne summoned read ichneumonid.
Page 93, line 6, for Agrotis read Eragrostis.
Page 146, line 13, for pe rsica, read persice.

Punk for Cabbage Plant-louse, 113. | Arsenicals for Apple Flea-weevil, 86.

Apple Flea-weevil, 83-86. for Bag-worm, 40.
infested by Cottony Maple Scale, for Forest Tent Caterpillar, 23.
62. for green fruit-worms, 78.
by Walnut Caterpillar, 8. for Gypsy Moth, 19.
injured by Apple Flea-weevil, 84, for Imported Cabbage-worm, 106.
85. for Poplar and Willow Borer, 44.
by green fruit-worms, 75, 76. for Strawberry Crown-girdler, 94.
by Oak Twig-pruner, 50, 51. for Striped Cucumber-beetle, 116,
by White-marked Tussock-moth, 118.
10. for Walnut Caterpillar, 9.
leaves, Taeniocampa alia reared on, for Yellow Poplar-Caterpillar, 8.
Wile use of, on Cabbage and Cauliflow-
-tree Borer, Round-headed, com- er, 106.
pared with Heart-wood Borer, 72. Ash, 62.
-trees honeycombed by Heart- Black, injury to, by Heart-wood

wood Borer, 70-71. Borer, 68-69.

160

mercially prepared fumigating papers are suspended in strips and
lighted when ready to fumigate. Dry preparations are placed in
shallow dishes and ignited. It is sometimes advisable to add a few
drops of kerosene to facilitate their burning. The extracts are evap-
orated over a lamp, or, like the sulphur paste, are painted on the
steam pipes. They evaporate or burn slowly, producing a powerful
vapor. Asa rule it is best to fumigate in the evening, keeping the
houses closed over night. Most insect pests of the greenhouse may ~
be controlled by thoro and oft-repeated fumigations with one of these
extracts.

INDEX

A.

acerni, Sesia, 35.
Agrilus anxius,
borer, Bronze.
Agrotis saucia, 107, 129.

Ailanthus, 60.
Alders injured by
low Borer, 40.
Aleyrodes vaporariorum, 121-123. See

Greenhouse White-fly.
alia, Taeniocampa, 77, 78-82.
Althea infested by San Jose Seale,
5g:
Amarantus retroflexus as breeding
plant of Onion Thrips, 124.
Ammann, J. F., 129.
Anarsia lincacella, 91.
Anasa tristis, 118-120.
Ancylis comptana, 86-89.
ancylus, Aspidiotus, 61.
Anomala binotata, 73-75.
species, 73.

53-55. See Birch-

Poplar and Wil-

antennata, Xylina, 77, 78, 79, 80, 82.
Aunthomyia brassicae, 108.

ceparum, 133.

radicum, breeding of, 136.
anxius, Agrilus, 53.

Apanteles glomeratus as parasite of
Imported Cabbage-worm, 106.
cocoons of, 105, 106.
Apatela populi, 6-8.
Aphis brassicae, 111-113.
cucumeris, 120.
dianthi, 146.
gossypii, 120-121.
lactucae, 132.
Melon, 120-121.
pisi, 138.
Punk tor Cabbage Plant-louse, 113.
Apple Flea-weevil, 83-86.
infested by Cottony Maple Scale,
62.
by Walnut Caterpillar, 8.
injured by Apple Flea-weevil, 84,
85.
by green fruit-worms, 75, 76.
by Oak Twig-pruner, 50, 51.
by White-marked Tussock-moth,
10.
leaves, Taeniocampa alia reared on,
Mile
-tree Borer, Round-headed, com-
pared with Heart-wood Borer, 72.
-trees honeycombed by Heart-
wood Borer, 70-71.

Arbor-vitae
Soe
by San Jose Seale, 60.
Archytes aterrima as parasite of Va-
riegated Cutworm, 131.
Arsenate of lead and Bordeaux mix-
ture for Cabbage Flea-

infested by Bag-worm,

beetle, 114.
for Colorado Potato-bee-
tle, 142.
for Potato Flea-beetle,
145.
composition and compara-

tive cost and rank of, as
insecticide, 150.
for Bag-worm, 40.
for Brown-tail Moth, 18.
for Catalpa Sphinx, 3.
for Common Asparagus-bee-

tle, 104.
for Common Canker-worm,
26.

for Fall Web-worm, 6.
for Gypsy Moth, 19.
for Imported Cabbage-worm,
107.
for Poplar and Willow Bor-
er, 44.
for Strawberry
89.
for Striped Cucumber-beetle,
116.
for Walnut Caterpillar, 10.
for White-marked Tussock-
moth, 14.
formula for, 89.
Arsenic and molasses for Locust Bor-
er DOE
Arsenicals for Apple Flea-weevil, 86.
for Bag-worm, 40.
for Forest Tent Caterpillar, 23.
for green fruit-worms, 78.
for Gypsy Moth, 19.
for Imported Cabbage-worm, 106.
for Poplar and Willow Borer, 44.
for Strawberry Crown-girdler, 94.
for Striped Cucumber-beetle, 116,
118.
for Walnut Caterpillar, 9.
for Yellow Poplar-Caterpillar, 8.
use of, on Cabbage and Cauliflow-

Leaf-roller,

er, 106.
Ash, 62.
Black, injury to, by Heart-wood

Borer, 68-69.

Ash— Continued.
English, Green,
White, injured by
Ze
infested by Putnam’s Scale, 61.
injured by White-marked Tussock-
moth, 10.
Mountain, infested by Putnam’s
Scale, 61.
by Scurfy Scale, 56.
injured by San Jose Scale,
59.
Prickly, 60.
White, infested by San Jose Scale,
59.
Ashes for Cabbage Flea-beetle, 114.
asparagi, Crioceris, 102, 103.
Asparagus, 99, 102-104.
beetle, Common, 102,
strength of insecticide for,
Agspidiotus ancylus, 61.
juglans-regiae, 61.
perniciosus, 58-60.
aterrima, Archytes, 131.

Mountain, and
Lilae Borer,

58,

103-104.
151.

B
Bacterial disease of Cabbage, 127.
Bag-worm, 38-40.
Rald Cypress, 60.
Balm of Gilead, 40.
injured by Memythrus dollii
and M. tricinctus, 31.
Balsam-root (Balsamorhiza sagit-
tata) as food plant of Strawberry
Crown-girdler, 92.
Baltimore Oriole as enemy of Forest

Tent Caterpillar, 21.
Barberry, 60.
Barnes, Dr. William, 79.

Basswood, Heart-wood Borer found
under bark of, 69.
injured by San Jose Secale, 59.
(See also Linden.)

Beach-plum infested by Viburnum
Borer, 34.
Beans, 99, 100.
immunity of, from wireworm in-
jury, 144.

lseech, Heart-wood Borer in, 68.
infested by Putnam’s Scale, 61.
by Walnut Caterpillar, 8.
injured by Cottony Maple Scale,
62.
Beets, 99.
bimaculatus,

binotata, Anomala, 73.
Birch-borer, Bronze, 53-55. X
Birch defoliated by White-marked
Tussock-moth, 10.
White, infested by Putnam’s Scale,
61.
destroyed by
er, 538, 54.

Tetranychus, 124.

Bronze Birch-Bor-

vi

Birches infested by San Jose Seale,
: 59.
injured by Bronze Birch-borer, 53,
54.
by Poplar and Willow Borer, 40.
Birds as enemies of Colorado Pota-
to-beetle, 142.
of Common or Spring Canker-
worm, 25.
of White-marked Tussock-moth,
14.
Bittersweet, 60.

injured by Cottony Maple Scale,
62.
Climbing, injured by Oak Twig-
pruner, 50.
Black Cherry, Wild, injured by Vi-
burnum Borer, 34.
Gum, 60.
injured by Forest Tent Cater-
pillar, 21.

-headed Grass-maggot, 96.
-knot of plum, Viburnum Borer
bred from, 34.
Blackberry as food plant of Black-
berry Leaf-roller, 94.
infested by San Jose Scale, 60.
Leaf-roller, collection and rearing
of, 94-95.
BPladderwort injured by White-marked
Tussock-moth, 10.
Blueberry, 60.
Bordeaux mixture and arsenaté of
lead. See Arsenate of lead.
and Paris green, combination
spray of, 151-153.
for Striped Cucumber-beetle, 118.
Borer, Heart-wood, 68-73. See Heart-
wood Borer. 3

Lilae, 27-31. See Lilac Borer.
Locust, 48-50. See Locust Borer.
Maple, 35-36.

Ninebark, 37-38. .
Poplar and Willow, 40-44. See Pop-
lar and Willow Borer.
Viburnum, 34-35.
Borers, poplar, 31-34.
borers.
Box-elder injured by Cottony Maple
Seale, 62.

See Poplar

by White-marked Tussock-moth,
10.
Bran mash, poisoned, formula for,
155.
brassicae, Anthomyia, 108.
Aphis, 111.
Pegomyia, 108.
Phorbia, 108.

Bronze Birch-borer, 53-55.
Brown-tail and Gypsy moths,
parasites of, 21.
powers of migration of, 14,
15.

14-21.

Beawe tail and Gypsy Moths—Continued.
relative rank of, as_ pests,
18.
Moth, annoyance from
caterpillar of, 18.
description of adult, 16.
of immature stages of, 17.
hibernating stage and nests of,
Sy, iG.
measures for control of, 18.
sources of introduction of, into
Tllinois, 15.
brunnea, Colaspis, 91.
Parandra, 68. .
Buhach. See Pyrethrum.

Burning birches infested with Bronze
Birch-borer, 54.
branches or trees

Lilac Borer, 30-31.
cabbage stalks, ete., as protection
against Imported Cabbage-worm,

107.
cucumber-vines, to destroy Striped
Cucumber-beetle, 118, Squash-
bug, 120, and Melon Aphis, 121.
fallen twigs to destroy larvae of
Oak Twig-pruner, 53.

hairs of

infested with

trees badly infested with Locust
Borer, 50.
with Poplar and Willow Bo-
rer, 44.

webs of Fall Web-worm, 6.
weeds and rubbish as affording
breeding places for cutworms,
Sie
Butternut, 60.
Walnut Caterpillar common on, 8.
Buttonbush, 60.
injured by White-marked Tussock-
moth, 10.
Cc
Cabbage, 99, 100, 129.
and Cauliflower, 104-114.
insects injurious to, 104.
club-root of, 127.
Flea-beetle, 113-114.
injured by Cabbage
12:
by Cabbage Root-maggot, 108.
by cutworms, 107.
by Imported Cabbage-worm, 104,
105.
by Limonius confusus,
Plant-louse, 111-113.
Root-maggot, 100, 101, 108-111.

Plant-louse,

143.

-worm, Imported, 104-107, 133.
-worms, cutworms, and _ potato-
beetles, insecticides for, 148.

eandicans, Populus, 31.

eandida, Saperda, 72.

canellus, Typophorus, 91.

Canker-worm, Common or Spring, 23-
26.

canus, Orchestes, 83.
Carbolic acid and lime for Cabbage
Root-maggot, 110.
formula for, 155.
and soft soap against Maple Bor-
er, 36.
emulsion for Onion-maggot, 136.
formula for, with directions
for making and using, 153-
154.
Carbon bisulfid for
LOWSe; lel Qadai3y
for Cabbage Root-maggot, 110.
for Melon Aphis, 121.
for weevils in seeds, 158.
how to fumigate with, 158-159.
Carolina Poplar, 7, 31, 40. See also
Poplar, Carolina.
Carrots, 99.
Catalpa, 62.
infested by San Jose Scale, 59.
injured by White-marked Tussock-
moth, 10.
Sphinx, 2-3.
description of, 3.
measures against, 3.
catalpae, Ceratomia, 2.
“Caterpillar, the,’ 22.
Caterpillar, Forest Tent, 21-23.
Walnut, 8-10.
Yellow Poplar, 6-8.

Cauliflower and Cabbage, 104-114.
insects injurious to, 104.
infested by Cabbage Plant-louse,
he
injured by

108.
by Imported Cabbage-worm, 105.
by Stalk-borer, 147.
Cedar, 60.
Red, infested by. Bag-worm, 39.
Celery, 99.
injured by Red Spider, 124.
Lettuce Plant-louse found on, 132.
eeparum, Anthomyia, 133.
Pegomyia, 133.
Phorbia, 133.
cepetorum, Pegomyia, 133.
Ceratomia catalpae, 2-3.
Chaetochloa viridis as food plant of
Onion Thrips, 124. }
Chalecid parasite of Apple Flea-wee-
vil, 86.
Cherry, Heart-wood Borer found un-
der bark of, 69.
infested by Viburnum Borer, 34.
injured by Common Canker-worm,
23.
by San Jose Scale, 59.
Sour, infested by San Jose Seale,

Cabbage Plant-

Cabbage Root-maggot,

59.
Wild Black, injured by Viburnum
Borer, 34.

Chestnut infested by Viburnum Bor-
er, 34:
by Ninebark Borer, 37.
by San Jose Scale, 59.
telegraph poles injured by Heart-
wood Borer, 69-70.
Chickens as enemies of Onion-mag-
got, 135.
Chionaspis furfura, 55-57.
Chittenden, F. H., 51, 52, 55, 69, 104,
107, 126.
Chrysomelidae, 91.
Chrysopa as enemy of Cabbage Plant-
louse, 112.
elrysorrhoea, Euproctis, 14.
Clover as hibernating plant of Pea-
louse, 139.

Club-root of Cabbage, 127.

Coffee-tree, Kentucky, 60.

Colaspis brunnea, 91. E

Colorado Potato-beetle, 141-143, 146-

147.

comptana, Ancylis, 86.

confusus, Limonius, 143.

Conifers, 10.

Cooley, R. A., 90, 92, 93, 94.

Corn as food plant of adult Straw-

berry Crown-girdler, 92.
destroyed by Stalk-borer, 147.
injured by Limonius confusus, 143.
roots, old, Anomala binotata found

among, 73.

Sweet, 100.
Sugar, Anomala binotata found in

fields of, 74.

Cornus sanguinea injured by

wood Twig-girdler, 47.
sp. injured by Ninebark Borer, 37.

Creosote, crude, to destroy egg mass-

es of white-marked Tus:ock-

moth, 14.
oil, carbolic acid, turpentine, and

coal-tar, mixture of, to destroy

egg masses of Gypsy Moth, 19.

Cottonwood infested by Poplar and

Willow Borer, 41.
Cottony Maple Seale, 62-67.
description of female of, 64.
history of, in Illinois, 62.
insecticide treatment for, 66-
67.

life history of, 64.

parasites and insect enemies
of, 62, 65.

trees and woody plants in-
fested by, 62.

Crataegus injured by San Jose Scale,
59.

Crepidodera cucumeris, 145.

Crioceris asparagi, 102, 1038-104..

Crown-borer, Strawberry, 91.

Crown-girdler, Strawberry, 90-94.

Dog-

viii

.
Crown-miner, Strawberry, 91.
Cryptorhynehus lapathi, 31, 40-44.
See Poplar and Willow Borer.
Cucumber and Melon, insect pests
of, 114-129.
-beetle, Striped, 100, 101, 115-118.
beetles, repellent and insecticide
for, 155.
immunity of, from wireworm in-
jury, 144.
injured by Eel-worm, 126-128.
by Greenhouse White-fly, 121.
by Red Spider, 124.
by *Squash-bug, 118, 119.
plants, injury to, 96.
Cucumbers, 100.
cucumeris, Aphis, 120.
_ Crepidodera, 145.
Hpitrix, 145.
Currant infested by San Jose Scale,
59.
injured by Ovyster-shell Scale, 58.
by Scurfy' Seale, 56.
Cutworm, Variegated, 107,
Cutworms, 100, 101. 104.
cabbage-worms, and potato-beetles,
insecticides for, 148.
remedies for, 131.
Cyllene robiniae, 48-50.
Cypress, Bald, 60.

129-132.

D

Datana integerrima, 8-10. See Wal-
nut Caterpillar.

Davis; Juv ly ety wiiosnel ayn oie

10-lineata, Doryphora, 141.
Leptinotarsa, 141.

deltoides, Populus, 31.

destructor, Nectarophora, 138.

Diabrotica vittata, 115-118.
dianthi, Aphis, 146.
Rhopalosiphum, 146.

dispar, Porthetria, 14.
disstria, Malacosoma, 21.
Dogwood infested by Dogwood Twig-
girdler, 45.
injured by Ninebark Borer, 37.
by White-marked Tussock-moth,
10. "
Cottony Maple Scale on, 62.
Red-osier, injured by | Dogwood
Twig-girdler, 47.
Red-twigged, injured by Oyster-
shell Scale, 58.
by Scurfy Scale, 56.
Twig-girdler, 44-47.
Dogwoods infested by San Jose Seale,
59.
dollii, Memythrus, 31.
Doryphora 10-lineata, 141.
Dunlaps As ge. v6:
Dunlap? HM. 76). 93.

BE
Fel-worm, 126-129.
as a Cucumber pest, 126-128.
Eggplant injured by Red Spider, 124.
by Stalk-borer, 147.
Eggs of Anomala binotata, 73.

of Apanteles glomeratus, 106.
.of Apple Flea-weevil, 85, 86.

of Bag-worm, 39, 40.

of Blackberry Leaf-roller, 94, 95.
of Bronze Birch-borer, 54, 55.
of Brown-tail Moth, 17.

of Cabbage Flea-beetle, 114.

of Cabbage Plant-louse, 112, 113.
of Cabbage Root-maggot, 108, 110.

of Canker-worm, Common or Spring,
24, 25.

Catalpa Sphinx, 3.

Colorado Potato-beetle, 142.
Cottony Maple Scale, 62, 64, 65,
(5 =
Dogwood Twig-girdler, 45, 46.
Eel-worm, 128.

Fall Web-worm, 6.
Forest Tent Caterpillar,
green fruit-worms, 78.
Greenhouse White-fly,
Heart-wood Borer, 72.
Imported Cabbage-worm, 104,
106.

Lilac Borer, 27, 28.

Locust Borer, 49, 50.

Maple Borer, 35, 36.

Melon Aphis, 121.

Oak Twig-pruner, 52.
Onion-maggot, 134,
Onion Thrips, 137.
Oyster-shell Scale,
Pea-louse, 139.
Phorocera rufilabris, 142.
Poplar and Willow Borer, 48.
poplar borer, 31.
Pteromalus puparum, 106.
Putnam’s Scale, 61.

Red Spider, 125.

Sciara sp., 97.

Scurfy Scale, 56, 57.
Squash-bug, 119.
Stalk-borer, 148.
Strawberry Crown-girdler,
93.
of Strawberry
89. E
Striped Cucumber-beetle, 115.
Taeniocampa laticinerea, 79.
Variegated Cutworm, 129,
Viburnum Borer, 34.
Walnut Caterpillar, 8.
Walnut or Willow Seale, 61.

of
of
of

of
of
of
of
of
of
of
of

22, 23.

122.

of
of
of
of
of
of
of
of
of
of
of
of
of
of
‘of
of
of
of
of
of

135, 136.

58.

92,

Leaf-roller, 87, 88,
of
of
of
of
of
of

130.

ix

Eggs— Continued.
of White-marked Tussock-moth, 10,

DS eae
Elaphidion villosum, 50-53.
Elder infested by San Jose Scale,
60.
Elm as food plant of Bronze Birch-
borer, 55.
defoliated by White-marked Tus-

sock-moth, 10.
infested by Putnam’s Scale, 61.
injured by Brown-tail Moth, 17.
by Common Canker-worm, 23, 26.
by Cottony Maple Scale, 62.
by Oak Twig-pruner, 51.
by Oyster-shell Scale, 58.
by San Jose Scale, 59.
by Scurfy Scale, 56.
by White-marked Tussock-moth,
10.
Emerick, Geo. W., 76.
Encarsia versicolor as parasite of
Greenhouse White-fly, 123.
English Ash injured by Lilac Borer,

PAT CU
Ivy, 60. :
ephemeraeformis, Thyridopteryx, 38.
I{pitrix cucumeris, 145.
Eragrotis major, 93- (see Errata):

Eulophus sp. ‘as parasite of Apple
Flea-weevil, 8&6.

Huproctis chrysorrhoea and Porthe-
tria dispar, 14-21. See Brown-tail
Moth and Gypsy Moth.

Evyergreens infested by Bag-worm, 39.

by Heart-wood Borer, 72.
injured by Gypsy Moth, 18.
Exartema permundanum, 94-95.

EF
Wall Web-worm, 4-6.
Invelhes” IDBe ee Ai Das.

Tir injured by Oak Twig-pruner, 50.
Hiteh, Asay pil, iil.
flava, Poa, 92.

Flea-beetle, Cabbage, 113-114. See
Cabbage Flea-beetle.
Potato, 145.
Tlea-beetles, 101.

screens for protection against, 109.
Flea-weevil, Apple, 83-86.
Fletcher, James, 57, 108,
Flint, W. P., 50.

Forest and shade trees injured by
green fruit-worms, 75.

* Tent Caterpillar, 21-23.

Forsythia infested by

Seale, 59.

Foxtail Grass as breeding plant of

Onion Thrips, 124.
fragariae, Tyloderma,
Fringe-tree, 60.

112.

San Jose

$1.

Fruit trees injured
Caterpillar, 21.
killed by- Brown-tail Moth, 17.
-worms, green, 75-82.
appearance and method of in-

by Forest Tent

jury by, 75-76.

differences in larvae, pupae,
and life histories of, tabu-
lated, 82.

distribution of, and serious in-
jiey bys. th

feeding period of, 77.
INjUTIES bys ibe Gs tte ta:
method of destroying, 78.
parasites of, 78.
transformations of, 77-78.
Fuma Carbon Bisulphide, 159.
I'umigation for Cabbage Plant-louse,
ila Pea ines
for Greenhouse White-fly, 123.
for Lettuce Plant-louse, 133.
for Melon Aphis, 121.
for Onion Thrips, 124, 138.
for Red Spider, 126.
with hydrocyanic acid gas, instruc-
- tions for, 156-158.
Fungous injury due to infestation
by Greenhouse White-fly, 122-123.
I'ungus fly in cucumber houses, 96.
furfura, Chionaspis, 55.
fusea, Lachnosterna, 74.
fusciceps, Phorbia, 111.

G

Gahan? Ab. 60. 72:
Galloway, B. T., 125.
1B

Garman, H.,- 3, 1 4 IG:
Gibson, Arthur, 69.

Ginko, 60.

Gairaule, “An Ac. Soper

glandulosa, Potentilla, 92.
#Zlomeratus, Apanteles, 106.

Gnats, black, in cucumber houses,

95-98. See Sciara sp.
Goding, F. W., 51.
Goldenrod flowers as food of Locust
Borer beetle, 49.
Gooseberry injured by
Seale, 59
Gortyna nitela, 147.
gossypii, Aphis, 120.
Crafting-wax on tree wounds to pre-
vent borer attack, 36.

San Jose

Grape infested by San Jose Seale,
60.
injured by Cottony Maple Scale,

62.
by Oak Twig-pruner, 50.
Grass, Foxtail, as breeding plant of
Onion Thrips, 124.
lands, Anomala binotata abundant
ims Ts:

-maggot, Black-headed, 96.

Grasses as food of Gypsy Moth, 19.
of Strawberry Crown-girdler,

90, 92.

Green Ash injured by Lilac Borer,

20g soUs
fruit-worms, 75-82. See Fruit-

worms, green.

Green, E. C., 96, 97, 98.

Greenhouse White-fly, 121-123.

grotei, Xylina, 78, 82.

Ground-beetles as enemies of Colo-
rado Potato-beetle, 142.
Gum, Black, 60.
injured by Forest Tent Caterpil-
lar 2ie
Sweet, 60.
injured by
Pillar, 21.
Gypsy and Brown-tail Moths, 14-21.
See Brown-tail and Gypsy moths.
Moth as a feeder, 19, 20.
description of stages of, 19-20.
destruction of eggs and cater-
pillars: of, 3195-20.
hibernation of, 19.
parasites of, 21.

TIorest Tent Cater-

: H
Hackberry infested by Putnam's
Seale, 61.
by San Jose. Seale, 59.
Hawthorn infested by Scurfy Scale,
56.
injured by Cottony Maple Scale, 62.
by San Jose Scale, 59.
Heart-wood Borer, 68-73.
character of attack by, 71.
compared with Round-headed
Apple-tree Borer, 72.
description of, 68.
distribution of, 70.
life history of, 72.

summary concerning, 72-73.
Heart Worm, 147.
Helianthus retroflexus as breeding
plant of Onion Thrips, 124.
Hellebore as repellent for Onion-
maggot, 136.
decoction for Cabbage Root-mag-
got, 109-110.
formula for, 154.
Hemerocampa leucostigma, 10-14.

See Tussock-moth, White-marked.
Hemlock, 60.

infested by
Heterodera radicicola,
Hewitt, C. G., 136.
Hickories, 60.

Oak Twig-pruner

Dike
Walnut Caterpillar on, 8.

Putnam’s Seale, 61.
126-129.

injurious to, 50,

Hickory injured by White-marked
Tussock-moth, 10.
Hodgkiss, H. E., 1.
Honey-locust infested by San Jose
Scale, 59.

by Walnut Caterpillar, 8.

injured by Cottony Maple Scale,
62.
Honeysuckle infested by San Jose
Seale, 59.
Cottony Maple Scale on, 62.
ELCOO eda ey wholes
Hopkins, A. BD., 48, -50.
inorn. (Ge en soe

Hornbeams, 60.
Horse-chestnut defoliated by White-
marked Tussock-moth, 10.

Cottony Maple Scale on, 62.
infested by San Jose Scale, 59.
injured by Oyster-shell Scale, 58.

Horseradish injured by Limonius con-
fusus, 143.

Eloward. ie O0-18.
Hubbard, Fred, 89.
Hulst, Geo. D., 30.

Hydrangeas, 60.
Hydrocyanie acid gas for Greenhouse
White-fly, 123.
for Lettuce Plant-louse,
for Melon Aphis, 121.
for Onion Thrips, 138.
for Red Spider, 126.
fumigation with, 156-158.
Hydroecia nitela, 147.
Hyphantria textor, 4-6.

133.

I

Ilex infested by Putnam’s Scale, 61.
Illinois shade trees and shrubs, some
important insects of, 1-67.
vegetable gardening in, 99, 100.

Insect pests of greenhouse, control
of, 160:
powder. See Pyrethrum.
Insecticides, classification and sy-

noptie list of, 149.
preparation of, 148-160.
Insects of Illinois shade trees and
shrubs, 1-67.
of the truck-farm
garden, 99-160.
integerrima, Datana,
Ivy, English, 60.

and vegetable

8.

J

Japanese Quince, infestation of, by
San Jose Scale, 58.

japonica, Pyrus, 58.

Jasmine, Yellow, 60.

Judas-tree, 60.

juglans-regiae, Aspidiotus, 61.

June Grass as food plant of Straw-
berry Crown-girdler, 92.

xi

Juneberry infested by Viburnum Bor-

er, 34.
Juniper, 60.
K
Kelly; -Bi.. ©: 2G:, 73.

Kentucky Coffee-tree, 60.
Kerosene for Walnut Caterpillar,. 9.
emulsion for Cabbage Plant-louse,

ilalsy
for Cottony Maple Scale, 66.
for Onion Thrips, 124, 137.
for Pea-louse, 140.
for Potato Plant-louse, 145.
for Scurfy Scale, 56-57.
for Squash-bug, 119.
formula for, 66-67, 153.
Koebele, Albert, 78.
L
Lace-wing fly, larva of, as enemy

of Cabbage Plant-louse, 112.

Lachnosterna, 75.
fusca, 74. t
implicita, 74.
lactucae, Aphis, 132.
Macrosiphum, 132.
Nectarophora, 132.
Siphonophora, 132.
Ladybirds as enemies of Cabbage

Plant-louse, 112.
of Colorado Potato-beetle,
(See also Ladybugs.)
Ladybugs and their larvae as ene-
mies of Cottony Maple Scale, 65.
Lantern-trap for moth of Variegated
Cutworm, 131-132.
lapathi, Cryptorhynchus,
Larches, 60.
Larsen, John, 55.
laticinerea, Xylina, 78, 79, 82.

142.

31, 40.

Laurel, Mountain, infested by San
Jose Scale, 59.
Leaf-roller, Blackberry, collecting

and rearing of, 94-95.
Strawberry, 86-89.
Leatherwood, 60.
Lepidosaphes ulmi, 57-58.
Leptinotarsa 10-lineata, 141-143.
Lettuce, 99, 100, 129-133.
as food plant of Variegated Cut-
worm, 129.
immunity of, from wireworm
jury, 144.
injured by Greenhouse
eis
by imported Cabbage-worm,
13a,
by Lettuce Plant-louse,
Plant-louse, 132-133.
leucostigma, Hemerocampa,

in-
White-fly,
105,

132.

10.

Lilac Borer, 27-31.
description of,
of adult, 30.
injuries in New York by, 30.
measures against, 30, 31.
places of deposit of eggs of, 27,
28.
trees injured by, 27, 30.
injured by Lilac Borer, 27, 30.
by Oyster-shell Scale, 58.
by San Jose Scale, 59.

29-30.

Lime, air-slaked, for Cabbage Flea-
beetle, 114.
for Common Asparagus-beetle,
104.

for Imported Cabbage-worm, 107.
and sulphur mixture, directions
for making, 60.
winter spray of, for San Jose
Seale, 60.
for Scurfy Scale, 56-57.
dry, as repellent for Onion-mag-
got, 136, and soft-bodied insects
generally, 156.
Limonius confusus, 143-144.
crops injured by, 143.
remedial measures against, 144.
Linden defoliated by White-marked
Tussock-moth, 10.
infested by Putnam’s Scale, 61.
injured by Cottony Maple Seale,
62.
(See also Basswood.)
lineatella, Anarsia, 91.
Mintner wie cArsatas 90).
Lloyd, J. W., 107.
Locust, Black, in Illinois, 48.
injured by Cottony Maple Scale,
62.
by Locust Borer, 48.
Borer, 48-50.
measures for control of, 50.
infested by San Jose Secale, 60.
injured by Oak Twig-pruner, 50.
by White-marked Tussock-moth,
10.
plantations, management of, 50.
Lugger, O., 69, 90.
Lye-sulphur spray for Red
126, 155.
formula for, 155.

Spider,

M

Macrosiphum lactucae, 132-133.
pisi, 138-140.
solanifolii, 145-146.
major, Eragrostis, 93 (see Errata).
Malacosoma disstria, 21-23. See For-
est Tent Caterpillar.
Maple Borer, 35-36.
Hard, 62.

injured by Maple Borer, 35.

Maple, Hard, injured—Continued.
by White-marked Tussock-
moth, 10.
infested by Putnam’s Scale, 61.
by San Jose Scale, 59.
injured by Brown-tail Moth, 17.
by Forest Tent Caterpillar, 21.
by Oak Twig-pruner, 50.
Norway, injured by White-marked
Tussock-moth, 10.

Scale, Cottony, 62-67. See Cot-'
tony Maple Scale.
Soft, base of, honeycombed by

Heart-wood Borer, 71.
defoliated by White-marked Tus-
sock-moth, 10.
injured by Cottony Maple Seale,
62.
by Maple Borer, 35.
margaritosa, Peridroma, 107, 129.
Matrimony-vine, 60.

Melon and Cucumber, 114-129.

Aphis, 120-121.
immunity of, from wireworm in-
jury, 144.

Melons, strength of insecticide for,
alisaly

Memythrus tricinctus and M. dollii,
31-34.

Mildew, sulphur for, 159.

Milk of lime, how to make, 151.
Mountain Ash infested by Putnam’s
Seale, 61.
injured by Lilac Borer, 27.
by San Jose Scale, 58, 59.
by Scurfy Scale, 56.
Laurel infested by San Jose Scale,
59.
Mulberry infested by San Jose Seale,
59.

Cottony Maple Scale on, 62.
Mycetophilidae, food of larvae of, 96.
Myrtle, Wax, 60.

Myzus persicae, 146. (See Errata.)

See Piant-louse, Omnivorous.

INI

nebulosus, Scelodonta, 91.

Nectarophora destructor, 138.
lactucae, 132.
solanifolii, 145.

Nematode injurious to Cucumber, 126.

Nickoteen for black gnats in cucum-
ber houses, 98.

Nico-Fume paper for Cabbage Plant-
louse, 113.

Nicotine extracts for
Plant-louse, 146.
preparations as fumigants, 159-160.

Ninebark Borer, 387-38.
infested by Poplar Borer, 34.
. injured by Ninebark Borer, 37.

Omnivorous:

nitela, Gortyna, 147.
Hydroecia, 147.
Papaipema, 146, 147.

Oo

Oak galls, Ninebark Borer bred from,
Bilis
Heart-wood Borer found in, 68, 69.
infested by Putnam’s Scale, 61.
by Walnut Caterpillar, 8.
injured by Cottony Maple Scale,

62.
by White-marked Tussock-moth,
10.
Twig-pruner, 50-53.
Oaks, 60.
injured by Forest Tent Caterpillar,
piles

Oak Twig-pruner bred from, and
injurious to, 50, 51.
Oats fields, Anomala binotata found
Thao (S nat (24

Oberea tripunctata, 44-47.

Omnivorous Plant-louse, 146.
Onion, 133-138.
insect enemies of, 133.
-louse, 137.
-maggot, 100, 101, 133-137.

Dhirips;ei23=024> 133. 137-138.
white blast of, 137.
Onions, 99, 100.
‘injured by Limonius confusus, 143.
Opulaster opulifolius, borer infest-
ing, 34.
injured by Ninebark Borer, 37.
opulifolius, Opulaster, 34, 37.
Orchards injured by Forest
Caterpillar, 21.
by green fruit-worms,. 76.
by Gypsy Moth, 19, 20.
by White-marked Tussock-moth,
10.
Orchestes canus, 83-86.
pallicornis, 84.
Osage Orange infested by Putnam’s
Seale, 61.
injured by Oak Twig-pruner, 50.
by San Jose Seale, 59.
Osten-Sacken, Baron R., 72.
Otiorhynchus ovatus, 90-94. See
Strawberry Crown-girdler.
avatus, Otiorhynchus, 90.
Oyster-shell Seale, 57-58.

Tent

12)

pacifica, Taeniocampa, 78.

Packard, A. S., 69:

Paleacrita vernata, 23-26.

pallicornis, Orchestes, 84.

Pansy-geranium infested by Green-
house White-fly, 123.

Papaipema nitela, 146, 147-148.

xili

Papaw, 60.

Parandra brunnea, 68-73. See Heart-
wood Borer.

Parasites and other enemies:

of Apple Flea-weevil, 86.

of Brown-tail Moth, 21.

of Cabbage Plant-louse, 112.

of Canker-worm, Common, 23.
of Colorado Potato-beetle, 142.
of Cottony Maple Scale, 65.

of Dogwood Twig-girdler, 47.

of green fruit-worms, 78.

of Greenhouse White-fly, 123.
of Gypsy Moth, 21.

of Heart-wood Borer, 69.

of Imported Cabbage-worm, 105-
106.
of Lettuce Plant-louse, 132-133.

of Onion-maggot, 135.
of Pea-louse, 139.
of Variegated Cutworm, 131.
of White-marked Tussock-moth, 13-
14.
Paris green and Bordeaux mixture
for Cabbage Flea-beetle,
114.
for Colorado
tle, 142.
for Potato Flea-beetle, 145.
carbolic acid, soft soap, and
soda against Lilac Borer, 31.
directions for using dry, 149-
150.
for Cabbage-worms, 106, 133.
for Catalpa Sphinx, 3.
for Colorado Potato-beetle,
for Common
104.
for Common Canker-worm, 26.
for cutworms, 107, 132.
for Fall Web-worm, 6.
for Striped Cucumber-beetle, 116.
for White-marked Tussock-moth,
14,
formula for liquid spray of, 150.

Potato-bee-

142.
Asparagus-beetle,

| Parsnips, 99.

Patch, Edith M., 90, 92, 94, 146.

Fea-louse, 138-140.

Feach infested by
Scale, 62.
by Viburnum Borer, 34.
injured by green fruit-worms, 75.
Oak Twig-pruner bred from and
injurious to, 50, 51.
Pear infested by San Jose Scale, 59.
by Scurfy Scale, 56.
injured by green fruit-worms, 75.
by Oak Twig-pruner, 50, 51.
liable to injury by Cottony Maple
Seale, 62.
Peas, 100.
garden, 138-140.

Cottony Maple

Peas— Continued.
immunity of, from wireworm
jury, 144.
Pecan, 60.
infested by San Jose Seale, 59.
Walnut Caterpillar on, 8.
Pegomyia brassicae, 108.
ceparum, 133.
cepetorum, 133.
Pepper, immunity of, from wireworm
injury, 144.
Veppers injured by
by Greenhouse White-fly,
Pepperbush, 60.
Peridroma margaritosa, 107, 129-132.
saucia, 107, 129.
permundanum, Exartema, 94.

Stalk-borer, 147.
121.

perniciosus, Aspidiotus, 58.
persicae, Myzus, 146. (See Errata.)
Persimmon infested by San Jose
Scale, 59.
Oak Twig-pruner bred from, 50.
Philadelphus, Cottony Maple Scale
found on, 62.

Phorbia brassicae, 108-111.
ceparum, 1338-137.
fusciceps, 111.

Phorocera rufilabris as parasite of
Colorado Potato-beetle, 142.

Phyllotreta sinuata, 114.
vittata, 113-114.

pictipes, Sesia, 34.

Pieris rapae, 104, 133.

Pigweed as breeding plant of On-
ion Thrips, 124.

Pine, 60.
Heart-wood Borer common under
bark ‘o£, 69:

pisi, Aphis, 138.
Macrosiphum, 138.
Siphonophora, 138.
Plant-beetles, 91.
Plant-lice, 100.
insecticide for, 154, 158, 159.

thrips, white-fly, etc., insecticides
for, 148-149.
Plant-louse, Cabbage, 111-1138.
Lettuce, 132-133.
Omnivorous, 146.
Potato, 145-146.
Plowing, fall, as means of insect

control, 101, 148.
Plum, black-knot of, Viburnum Bor-
er bred from, 34.

-cureculio, 90.
infested by
62.
by Viburnum Borer, 34.
injured by green fruit-worms,
by Oak Twig-pruner, 50.

Cottony Maple Scale,

75.

Poa flava as food plant of Straw-
berry Crown-girdler, 92.
serotina, 92.

Podosesia syringae, 27-31.
Borer.

Vontia rapae, 104-107, 133.

Poplar and Willow Borer, 40-44.

burrows of, 42.
description of adult of, 42-
43.
of larva of, 42.
indications of injury by, 42.
introduction and spread of,
40, 41.
life history of, 42, 438.
measures against, 44.
as food plant of Bronze Birch-bor-
Cl nies
borer bred from, 34.
borers, 31-34.
Carolina, 7, 40.
infested by poplar borers, 31.
injury to, by Yellow Poplar-Cater-
pillar, 7.
-Caterpillar, Yellow, 6-8.
injured by Cottony Maple Seale,
62.
by Oyster-shell Secale, 58.
by Poplar and Willow Borer, 40.
by poplar borers, 31, 34.
by San Jose Scale, 59.
by White-marked Tussock-moth,
10.

populi, Apatela, 6.

Populus candicans, 31.

Porthetria dispar and Euproctis chry-
sorrhoea, 14-21. See Brown-tail
Moth and Gypsy Moth.

Potato, 99, 100, 140-146.

-beetle, Colorado, 141-1438.
-beetles, 100, 101.
cabbage-worms, and
insecticides for, 148.
destroyed by Stalk-borer,
Flea-beetle, 145.
Plant-louse, 145-146.
principal insect enemies of, 141.
rank of, as a crop in Illinois, 140.

Potatoes injured by Limonius con-
fusus, 148.

Potentilla glandulosa as food plant
of Strawberry Crown-girdler, 92.

Poultry as enemies of Colorado Po-

tato-beetle, 142.
of Onion-maggot, 135.

See Lilac

cutworms,

147.

Preston, W. F., 128.
Frickly Ash, 60.
Frinters’ ink as protection against

Canker-worm, 26, and Forest Tent
Caterpillar, 23.
Prunus infested by

61.

Putnam’s Seale,

Ptelea injured by White-marked Tus-
sock-moth, 10.

Pteromalus puparum as parasite of
Imported Cabbage-worm pupae,
106.

Fulvinaria vitis, 62-67. See Cottony
Maple Scale.

Pumpkin, adult Strawberry Crown-
girdler found at roots of, 92.

puparum, Pteromalus, 106.

Putnam’s Scale, 61.

Pyrethrum .for Imported Cabbage-
worm, 107.

Pyrus japonica, infestation of, by
San Jose Scale, 58.

Q

Quaintance, A. L., 112.
Quince injured by green fruit-worms,
am, Aes
by Oak Twig-pruner, 50.
by San Jose Scale, 59.
Japanese, infestation of, by San
Jose Secale, 58.

R

radicicola, Heterodera, 126.
radicum, Anthomyia, 136.
Radishes, 99, 100.
injured by Cabbage Flea-beetle,
an hR
by Limonius confusus, 143.
rapae, Pieris, 104, 133.
Portia, 104, 133.
Raspberry as food plant of Black-
berry Leaf-roller, 94.
infested by San Jose Scale, 60.
Red Birch injured by Poplar and
Willow Borer, 40.
Cedar infested by Bag-worm, 39.
-osier Dogwood injured by Dog-
wood Twig-girdler, 47.
Spider, 124-126.
-twigged Dogwood injured by Scurfy
Seale, 56.
Kedbud injured by Oak Twig-pruner,
50.
Reed, Shelby, 68.
Remedies and preventives for in-
sect depredations:
Aphis Punk, 113.
arsenate of lead, 3, 6, 10; 14, 18,
LOS E26: 40,4489; 104, 107,
IAS AGS 4D 145, 150:
and Bordeaux mixture, 114,
W425 145.
arsenic and molasses, 50.
arsenicals: (8, 9, 19, .23,°40, 44, 50;
Tos SO woe 94, 1045 106; a07,. 146.
ashes, 114.
banding tree trunks, 14, 20, 23,
24, 26; 78.

Remedies— Continued.

“blood and bone’’ with hellebore,
alalals
Bordeaux mixture, 116, 118.
and arsenate of lead, 114, 142,
145.
and Paris green, 114, 142, 145,
IRs laa aCe
bran mash, pcisoned, 132, 155.
brush and cultivator method, 140.
buhach. See Pyrethrum.
burning bags of Bag-worm, 40.
infested plants, 148.
trees, 31, 44, 50, 54.
twigs or branches, 6, 8-9, 23,
SO RSU Os) Dos
over, fields, $9; 148, 112.0.
webs of Fall Web-worm, 6.
winter nests, 18.
earbolic acid and lime mixture,
DEO lbs
and soft soap, 36.
emulsion, 110, 136, 153.
carbon bisulfid, 110, 112, 121, 158-
15:9.
clean culture, 100, 107, 110, 113,
114, 118, 120, 121, 128-124 132,
DSM) AEBS al bys B3e
contact insecticides, 149.
covering tree wounds, 36, 44.
creosote, crude, 14.
oil, carbolic acid, turpentine, and
coal-tar, mixture of, 19.
destruction of egg masses, 14, 19,
Ber elo lO}.
digging out borers, 36, 44.
dust or liquid sprays, 149.
fertilizers,’ 110, 137, 156.
fumigants, 149.
fumigation, 112-113, 121, 123, 124,
126; 133, L385 Wb6-58.
hand-picking, 8, 40, 107, 132, 136.
hellebore, 109-110, 136, 154.
hot water, 107.
hydrocyaniec acid gas, 121, 123, 126,
133, 156-158.
insect powder. See Pyrethrum.
jarning Insects. from) trees) S278.
keeping down volunteer’ growth,
104.
kerosene, 9.
emulsion, 56-57, 66, 113, 119, 124,
POM AOS arabe lis.
lime, L047 M07, ila, 2365 156:
and sulphur, winter spray of, 56-
Fils OO-
lye-sulphur spray, 126, 155.
Nico-Fume paper, 113.
nicotine preparations, 146, 154, 159-
160.
painting trees, 31, 36.

xvi

Remedies— Continued.

Paris!-green,73, 6; 245526; 204, a06,
LOT As AG hs Ol S'S aad Oe
149-150.

and Bordeaux mixture,
142, 145, 151-153.
with flour, 142, 149-150.
with land-plaster, 104, 149-150.
with lime, 104, 114, 142, 149-
150.
and flour, 104.
with soft soap, soda, and ecar-
bolic acid, 31.

114,

plowing, siall, L015 0S Wot 139):
138, 144, 148.

poisoned baits, ROM Seelra lease ar
149, 155.

pyrethrum, 107, 154.

repellents, .98, 210; 14 118) 136;
149.

resin-lime mixture with Paris

green, 106, 150-151.
rotation of crops, 94, 100-101. 132,
144,
screening seed-beds, 108-109, 114.
young plants, 116.
soap mixtures and solutions,
124, 126, 145.
soot, 114.
steam to sterilize soil, 128-129.
sulphur, 126, 159.
suppressing volunteer growth, 104.
tarred-paper cards, 110.
time of planting, 101.
tobacco decoction, 113, 154.
dust, 110, 114, 136, 155-156.
extracts, 23. adiz4ds 133. 146.
stems, 123, 159:
trap crop, 116-118.
lantern, 131-132.
trapping under boards, 119.
with old onions, 136.
wash for tree trunks, 36.
water, 109, 125.
Whale-oil soap solution, 126,
140, 153.
whitewash, .57.
Resin-lime mixture with Paris green,
106, 150-151.
retroflexus, Amarantus,
Helianthus, 124.
Rhododendrons, 60.
Khopalosiphum dianthi,
Rhubarb, 99.
immunity of, from wireworm in-
juny, 144,
injured by Stalk-borer, 147.
Riley CaMV .; (6S vio:
Robber-flies as enemies of Colorado
Potato-beetle, 142.
robiniae, Cyllene, 48.
Root-lice, fumigant for, 158.

113,

137,

124.

146.

Root-maggot, Cabbage, 100, 101, 108-
aia fie
Root-maggots, repellents and insecti-
cides for, 155, 158.
Root-worms, Strawberry, 91.
Rosaceous plants, Scurfy Seale on,
56,
Rose injured by San Jose Seale, 58,
59,
Rotation of crops as_ protection
against insect pests, 100.
for cutworms, 132.
for Strawberry Crown-girdler,
94.
for wireworms, 144.
Rove-beetles as enemies of Colorado
Potato-beetle, 142.
Rudd, W. N., 129.

rufilabris, Phorocera, 142.
Ss
sagittata, Balsamorhiza, 92.
Salvia infested by Greenhouse White-
fly, *1:23.
San Jose Scale, 58-60.
Sanborn, C. E., 113.

sanguinea, Cornus, 47.
Sassafras infested by San Jose Scale
60.
saucia, Agrotis, 107,
Peridroma, 107, 129.
Scale, Cottony Maple, 62-67.
Oyster-shell, 57-58.
Putnam's, 61.
San Jose, 58-60.
Sceurty,. 55=57.
Walnut or Willow, 61.
Scelodonta nebulosus, 91.
Schoene, W. J., 108, 114.
Sciara larvae, general description of,
96.
sp. in cucumber houses, 98.
effect of Nickoteen appli-
cations as repellent for,
98.
food preferences of larvae
ef, tested, 97-98.
results of investigation of,

129.

98.
scitula, Sesia, 37.
Scurfy Scale, 55-57.
compared with Oyster-shell Seale,
58.

serotina, Poa, 92.
Sesia acerni, 35-36.

pictipes, 34-35.

scitula, 37-38.
Shimer, Henry, 114.
sinuata, Phyllotreta,
Siphonophora lactucae,

pisi, 138.

solanifolii, 145.
Sirrine, Gh Ar. A06, daliGseilSamulcoe

114.
132.

xvii

Slimeerland> IV. Vin bb; 77, 78, 79, 80,
82.
Smith, John “By bb:
Smoke-bush infested by San
Scale, 59.
Smoke-tree, Cottony Maple Scale on,
62.
Snowberry injured by San Jose Scale,
59.
Cottony Maple Scale on, 62.
Snyder, T. E., 69, 72.
solanifolii, Macrosiphum, 145.
Nectarophora, 145.
Siphonophora, 145.
Soldier-bugs as enemies of Colorado
Potato-beetle, 142.
Soot as repellent for Cabbage Flea-
beetle, 114.
Seur Cherry
Scale, 59.
Sphinx, Catalpa, 2-3.
Spice-bush, 60.
Spider, Red, 124-126.
Spiders as enemies of Colorado Po-
tato-beetle, 142. _
Spinach, 146.
immunity of, from wireworm in-
jury, 144.
injured by Stalk-borer, 147.
Spiraea infested by San Jose Scale,
60.
Cottony Maple Scale on, 62.
Spruce, White, infested by San Jose
Scale, 59.
Squash as’ trap crop for Striped Cu-

Jose

infested by San Jose

cumber-beetle, 116-118.
-bug, 118-120.
Stalk-borer, 141, 146, 147-148.

Steam to sterilize soil, against Eel-
worm, 128-129.
Strawberry as food plant of Black-
berry Leaf-roller, 94.
Crown-girdler, 90-94.
character of injury by, 90, 91,
91-92.
compared with
ry insects, 91.
distinguishing characters of ad-
Tt, (On
distribution of, 90.
food plants of, 92.
life history of, 92-93.
literature of, 90.
remedial measures for, 94.
serious injury by, 90, 93, 94.
stages of, 90-92.
injured by Strawberry Crown-gird-
ler, 90, 93-94.
insects, larvae of, compared, 91.
Leaf-roller, 86-89.
root-worms, 90-91.

other strawber-

Sulphur, directions for
with, 139.
for mildew, 159.
for Red Spider, 126.
Sumach infested by San Jose Scale,

fumigating

59.
injured by Cottony Maple Scale,
62.
by Oak Twig-pruner, 50.
Sunflower, Wild, as breeding plant
of Onion Thrips, 124.
Sweet Corn, 100.
Gum, 60.
injured by Forest Tent Caterpil-
lars e2dls

Sycamore, 60.
injured by White-marked Tussock-
moth, 10.
Syringa, 60.
False, Cottony Maple Scale found
on, 62.
syringae, Podosesia, 27.

‘ Ad
tabaci, Thrips, 123, 137.
Tachina fly as parasite of Colorado
Potato-beetle, 142.
Tachinid flies as parasites of Varie-
gated Cutworm, 131.
Taeniocampa alia, 78-80, 82.
pacifica, 78.
species destructive in orchards, tte
Tanglefoot against Tussock-moth cat-
erpillar, 14, and Locust Borer, 50.
Taylor, E. P., 84, 85.
Taylor, E. R., 159.
telarius, Tetranychus, 124.
“Ment caterpillar,” 5, 22:
Tent-caterpillar, Common, 22.
Tetranychus bimaculatus, 124-126.
telarius, 124.
textor, Hiyphantria, 4.
Thorn, Walnut Caterpillar found on,
8.
Moripss el! 007th 9).
Onion, 123-124, 133, 137-138.
plant-lice, white-fly, etc. class of
insecticides for, 148-149.
tabaci, 123-124, 137-138.
Thyridopteryx ephemeraeformis, 38-
40.
Tiger-beetles as enemies of Colorado
Potato-beetle, 142.
Timothy as food plant of Strawberry
Crown-girdler, 92.
Titus: sHaes. (G., 84,) So.
Tobacco decoction for Cabbage Plant-
louse, 1138. ?
directions for making, 154.
dust as repellent for Cabbage Flea-
beetle, 114.
for Cabbage Root-maggot,
110.

xviii

‘Tobacco dust as repellent— Continued.
for Onion-maggot, 136.

for Omnivorous Plant-louse, 146.

or tobacco extracts as fumigants

for Lettuce Plant-
louse, 133.
for, Onion “Thrips: =124;,
138.
stems, directions for fumigating
with, 159.
as fumigant for Greenhouse
White-fly, 123.
Tomato, 146-148.
destroyed by Stalk-borer, 147.

injured by
Ad:
by Limonius confusus, 143.

insect injury to, 146-147.

strength of insecticide for,
Tree of heaven, 60.
tricinctus, Memythrus, 31.
tripunctata, Oberea, 44.
tristis, Anasa, 118.
Trumpet-creeper, 60.

Cottony Maple Seale on, 62.
Trumpet-vine, 60.
Tulip-tree, 60.
Turnips injured

fusus, 143.
Tussock-moth, White-marked,

description of adult, 13,
of caterpillar of, 10.
life history of, 10-13.
measures against, 14.
parasites of, 13.
Twig-girdler, Dogwood, 44-47.
Twig-girdlers, egg-placing of,”
Twig-pruner, Oak. 50-53.
Tyloderma fragariae, 91.
Typophorus canellus, 91.

Greenhouse White-fly,

151.

by Limonius con-

10-14.

44,

Gh
ulmi, Lepidosaphes, 57.

Vv

vaporariorum, Aleyrodes, 121.

vernata, Paleacrita, 23.

veriscolor, Encarsia, 123.

Viburnum infested by San Jose Scale,
60.

injured by Viburnum Borer, 34.
by White-marked Tussock-moth,
10.
villosum, Elaphidion, 50.
Virginia Creeper infested by San Jose

Scale, 59.
injured by Cottony Maple Scale,
62.
viridis, Chaetochloa, 124.

vitis, Pulvinaria, 62.

vittata, Diabrotica, 115.
Phyllotreta, 113.

Ww
Walnut, Black, infested by San Jose
Scale, 59.
injured by Cottony Maple Seale,
62.
Caterpillar, 8-10.

or Willow Scale, 61.
Washburn, F. L., 109, 148.
Water-locust infested by Putnam’s
Scale, 61.
Wax Myrtle, 60.
Web-worm, Fall, 4-6.
Weed, C. M., 90.
Whale-oil soap solution for
Phrips; pol.
for Pea-louse,
for Red Spider,
formula for, 1538.
White Ash as breeding plant of Li-
lac Borer, 30, and injured by,
27.
infested by San Jose Scale, 59.
Birch, infested by Putnam’s Scale,
61. 3
by Bronze Birch-Borer, 53.
blast of Onion, 137.
Clover as food plant of Strawber-
ry Crown-girdler, 90, 92, 94.

Onion

140.
126.

-fly, Greenhouse, 121-123.
thrips, and plant-lice, insecticides
for, 148-149.
-grubs, 101.

Whitewash for Securfy Scale, 57.
Willow as food plant of Bronze Birch-
borer, 55.
. infested by Putnam’s Scale, 61.
by Walnut Caterpillar, 8.
injured by Cottony Maple Scale,
62.
by Oyster-shell Scale, 58.
by Poplar and Willow Borer,
40, 41.
by San Jose Scale, 59.
by Walnut or Willow Seale, 61.
by White-marked Tussock-moth,
10.
by Yellow Poplar-Caterpillar, 7.
Memythrus tricinctus bred from,
Siilis
or Walnut Scale,
Weeping, 40.
Wireworms, 101, 143-144.
plants practically uninjured
144.
remedial measures against, 144.

61.

by,

Malti GeO... 90) : Xylina—Continued.

Wistaria, 60. antennata, 77, 78, 79, 80-81, 82.
Cottony Maple Scale on, 62. grotei, 78, 82.

Witch-hazel, 60. laticinerea, 78, 79, 82.

Woodpeckers as enemies of Heart-
wood borer, 69.
pd

Yellow Jasmine, 60.
Poplar-Caterpillar, 6-8.

x
Xylina, larvae of, injuring fruit, 77.
and Taeniocampa, 75-82. See Tae-
niocampa, and Fruit-worms, green.

ae oy! ?
Ps Sour: P= Prem ‘>

Sy a th
Thre

Vk a
hie er, ik |

4

ay 4 i ;

iat

i MW aaa ny )
' re h pie hi t

bs

: a ¥!

a Pie
is?
Cae ulale

es ee
te)

i a ey

ae

i
Lia

MA P|
ia
Tay 4 ‘

ie te
i m4

wi
WW
Ui

Bee abel

Ph A Saeragen

j j
VEN! ce
¢ 1h

AS

iva alah labial
Peps ERE sel {| ane nas

A re iets
| Sang

Pepa

AA An ae
| Anan’ reir I ane ay

aa
Pease? |

te

en AMA re es a i
A Anarene i Raa anane Diba nat
| | wis | | mn AR lal) anannat

lel rat eis Pe TY
pon Perea eat te 8 |

aA ia ATT a Pe ui i
: AAA ree ae toca eile
wankdnnce: ‘ot conor EET TAY T EA

2b ISIE Ee | 5 aa

PETE TL.

~

ath
“aia
maatttmnat Aaa

‘ear s

IVY \elalglala

“on Joseph

aes

~

r->T *

Fr
RA

f NR oa atl all a

Lane ARAR: A

~ sae RGennatannee, Ne
:

SMITHSONIAN INSTITUTION LIBRARIES

Tn