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461

U53
“7 | Seventeenth Report

State Entomolo#ist
of Minnesota

To the GOVERNOR /
By A. G. RUGGLES
ZALLS 4

| ; Agricultural Experiment Station
University Farm, St. Paul, Minnesota
December 1, 1918

i Minnesota: OW Eft
9

US$

EW]

Seventeenth Report
State Entomologist of Minnesota

To the GOVERNOR

By A. G. RUGGLES 7 an
canian Ines;
“tle

+X

f ]
SUBJECT INDEX

Page

General report on insect conditions in 1918, Publications, Financial State-
mamesone Biol Ince Gri INsiryeinynen, IBY VAG IG. IaierelleSo 5555 4ocg Ince d husk oe 3

Life History of an Oak Twig Girdler, (Agrilus arcuatus Say and var. tor-
GRINS JES Cs)\y EWING (Gre M Rebietoal (Scents ee cent aio eh Gis ais omacio eS colo ae owe 15
torent, Somers rin Winomesouay. ley So Nk Cres yin. oaolucoscddeueccocenoeds 21
The Carpenter Ant as a Destroyer of Sound Wood. By S. A. Graham.... 32
Drosophila in’ Bottled Certihed Milk. By Wn Az Riley......5;°. = vache hee s 4]

Contribution to Knowledge of the Tribes and Higher Groups of the Family
Apiididae Cbomoptera). By (Ol We Oestlundssccne. see. ene aoe 46

The Confused Flour Beetle (Tribolium confusum Duval). By R. N.
(@hiebp rival sp cheeses steeeas circ saree Saracen ae seme aa ea ee Us gee 73

The Clover Seed Chalcid (Bruchophagus funebris Howard). By Warren
Wall ienm SO tate way. oe tis atea cone ee ac oboe witty sae anne eek apace oneal a ca ciire RIO estate ees toner arene 95

A Preliminary Report on the Trombidiidae of Minnesota. By C. W. Howard 111

The Hymenoptera of Minnesota. By F. L. Washburn.................... 145

Mines otambanhennyalmsradi cation, Wawenr-msnciin: ceieack cite ciiateeie citer ies 239

Agricultural Experiment Station
University Farm, St. Paul, Minn.
December 1, 1918

ae

Published April 10, 1919

December 1, 1918.
To His Excellency J. A. A. Burnquist,
Governor of the State of Minnesota.
Dear Sir:

In compliance with the Revised Laws of Minnesota 1905, Chapter
38, Section 2382, I have the honor to present herewith a report of the
State Entomologist for the year ending December 1, 1918.

A typewritten report for the year ending December 1, 1917, cover-
ing the year’s work in nursery inspection and other duties of the State
Entomologist was sent you in December, 1917, by Professor Washburn
and a published report of the work on the White Pine Blister Rust by
Mr. Washburn took the activities of the State Entomologist practically
up to February, 1918. At that time the writer assumed the duties of
this office, Professor Washburn having resigned the office of State
Entomologist to continue his work in the university as zoologist of the
Experiment Station.

As the insect work of the year 1918 had not begun, plans for
the growing season were developed immediately. There were two main
phases of the work to be kept in mind; one the purely mechanical work
of inspection, and the other the carrying on of plant pest campaigns.
Besides these two main functions, experimental insect control problems
had to be conducted in connection with the Experiment Station work.
The policy adopted was that the two main functions mentioned should
be carried on at the same time; that the nursery inspection work
should be closely merged with the educational or extension work and
that the inspectors would then be looked upon not as policemen but as
associates and helpers. The policy was to work in every possible way
to keep plant pests out of the state, but if any should become established,
to find the best method of controlling them and assist the nurseryman,
orchardist, gardener and others in their control.

This policy was followed very closely during the last season and
has produced excellent results.

As the chapter of the Minnesota law previously quoted makes the
State Entomologist responsible for combating insect pests and plant
diseases, the work this year naturally divided into four groups:

1. The inspection of nurseries ;

2. The control of white pine blister rust;

3. The eradication of the common barberry ;

4. The study of life histories and control measures for insect
pests.

4 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Fretp Crop INSECTS

Two or three regions in the state were threatened this year with
a grasshopper outbreak. In two instances considerable damage was
done. From May to July we were very fortunate in procuring through
the United States Department of Agriculture an extension man for
field crop insects. Mr. Marshall Hertig, a graduate of Minnesota, was
sent here at our request and we were well satisfied with his work.
When the work was at its height he was called in the draft and is now
serving the country in France. Mr. Hertig devoted his time principally
to the grasshopper situation. He had it well in hand and was planning
a vigorous campaign for the fall and winter among the farmers.

White grubs did considerable damage, but as this was not the year
for their worst attack, we are planning a campaign for 1919 and 1920.

The sugar beet web worm made its appearance and did consider-
able damage to sugar beets, flax and clover in Chippewa, Kandiyohi,
Grant and Polk counties. At Clara City, we tried arsenate of lead
powder in a power dusting machine. The insects were controlled, but
whether the cost of spraying warrants such a control method is yet to
be determined.

Wireworms did considerable damage in small areas of the state
and continue to offer interesting problems. To date, no solution of
the difficulty has been found.

Probably by far the most important insect of the garden was the
cutworm. During the cutworm season from twenty to thirty telephone
calls a day and innumerable letters pertaining to this insect were re-
ceived. In almost every case where poisoned bran mash was used as
directed, the cutworms were easily kept in check.

TREE INSECTS

Among the numerous orchard insects which have made their ap-
pearance in the state is the leaf crumpler of the apple. The increasing
abundance of this pest cffers further problems for investigation.

Tussock moths and canker worms are still on the increase. It is
only where communities decide upon vigorous co-operative measures
that these pests will be kept in control.

The oak twig girdler was in evidence this year, doing a great
amount of damage to the oaks of the lawns and boulevards. Unfor-
tunately the only control measure is the very expensive one of cutting
out all diseased branches of the affected trees and burning them with
their insect contents.

Insect Notes For 1918 5

Carpenter ants are responsible for an immense amount of damage
to standing white cedar in the northern part of the state. The in-
festation varies from 15 to 20 per cent of all swamp trees of pole size
and from 40 to 75 per cent of the trees on higher ground. S. A.
Graham, of this department, has investigated the injury. He believes
that altho it is impractical to suggest methods of protecting the standing
trees from injury by ants, the loss occasioned by them may be reduced
to comparatively small proportions if we discourage wasteful practices
in the woods.

PoTaTo SPRAYING

In an experiment to determine the comparative value of lead
arsenate, calcium arsenate, zinc arsenite and paris green, it was found
that when applied under favorable conditions, the poisons were equally
effective in poisoning the colorado potato beetles. The favorable condi-
tion necessary is dry weather such as we had in 1918 which makes it
possible for the poison to remain on the plants for a long time. Under
less favorable conditions, those materials which are easily washed from
the leaves would have been the less effective.

These results show that two factors determine the comparative
value of the stomach poisons: (1) Ability to stick in spite of rains and
a2 )e the Cost.

Preliminary work in testing the power of adherence of these com-
pounds indicates that both lead arsenate and calcium (lime) arsenate
are resistant to washing, while paris green washes off very readily.
Calcium arsenate (arsenate of lime) is the cheapest of these poisons
and therefore is the most desirable for potato spraying.

IXxperiments for the control of leaf hoppers on potatoes showed
that the commercial tobacco extracts with soap were effective as con-
tact sprays, provided the insects were hit with the material. The
problem of leaf hopper control, therefore, is a problem of perfecting
the mechanics of application.

ORCHARD AND Nursery INSPECTION

During the entire growing season 146 nurseries have been in-
spected and 100 certificates issued. We have also given 11 certificates
to dealers in nursery stock. For the most part the nurseries of the
state were found to be in excellent condition. No dangerously in-
jurious insect or disease was found, necessitating quarantining any
nursery or refusing a certificate. In a few instances barberry eradica-
tion and white pine blister rust called for extra precautionary measures,

6 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

but our inspectors proved efficient and the condemned plants were
destroyed. With the added work of barberry eradication and the extra
vigilance necessary to keep injurious insects and diseases out of the
state, an increase in the funds for nursery inspection must be made.

WHITE PINE BLISTER Rust

During the season just past, we have co-operated very closely with
the United States Department of Agriculture on the control of white
pine blister rust. The federal authorities spent practically $20,000 in
the state this last year, while the state spent $7,500.

Three phases of the work were emphasized in Minnesota (1)
scouting, (2) eradication, (3) nurseries and leads. To better the work
in Minnesota, Dr. E. M. Freeman, chief of the division of plant pathol-
ogy and botany of the Experiment Station, personally guided the work
of scouting. Professor Cheyney, the forester of the Experiment Sta-
tion, took personal charge of eradication and the writer the leads and
nurseries. This arrangement, altho somewhat cumbersome in details
of office work, worked out very nicely under the co-operative plan.
The work is now so well in hand that next year, if the work continues,
the State Entomologist will take immediate charge of the three phases
of the project.

Like the black stem rust of wheat, the white pine blister rust has
two hosts, each necessary before the disease can complete its life cycle—
the common gooseberries and currants and white pines. If there were
no currants and gooseberries, there would be no fear of the white pine
being infested with blister rust. In the scouting work, therefore, the
disease is looked for both on pine trees and currant and gooseberry
bushes. The thirty places, for the most part in the Saint Croix Valley,
reported last year as being infected, were scouted thoroly again this
year as well as the entire country surrounding this area. In six of these
places the disease was again found, but on only two areas had the dis-
case spread beyond the area of infection of last year. The entire
area around the infections for the width of two counties was scouted,
and no disease was found. In the badly infested areas, the infested
pines and gooseberries within a radius of one third of a mile were
destroyed.

A total of 994 white pine plantings were inspected this year. In
addition to this 353 leads were followed where no white pines were
found. Approximately 110,000 white pines were inspected during the
season, and 1,617 were destroyed to prevent possible infection. Five

Insect Notes For 1918 7d

new infections were found by means of the leads, but these were soon
eradicated.

The small number of new infections found and the fact that the
old infections are confined within rather narrow limits, seems very
encouraging. In spite of the fact that it takes several years for the
disease to show itself, we believe that there is a chance of entirely
eradicating it within the state. If given an appropriation to continue
the work for two years more, we shall be able either to eradicate the
disease or to recommend means for keeping it under control. The
white pine lumber of the state is so valuable that with such a possibility
before us, it would seem folly not to spend the small appropriation
needed for the trial.

BARBERRY ERADICATION

On March 19, 1918, the Minnesota Commission of Public Safety
passed an order making the State Entomologist responsible for the
eradication of the common barberry (B. vulgaris) and all its varieties.
This order, No. 28, declared these bushes to be a public nuisance and
a menace to the public welfare, and their maintenance, propagation,
sale or introduction into the state was forbidden. Whenever these
bushes were located, the owner was to be notified that these dangerous
bushes were growing on his premises and that he must forthwith
destroy them.

The United States Department of Agriculture had at this time
already started a campaign of education regarding the dangerous char-
acter of these plants, and as federal scouts were at work in the state, a
hearty co-operation was effected. Much publicity had been given to the
movement and probably four or five times as many bushes as we have
actual record of, were destroyed before active scouting occurred. To
date, all the counties of the state have been scouted except three, and
in two others no barberries have been found. We have records of more
than 50,000 plants dug up and destroyed from the ordinary plantings
of city, town and summer residence lots. In the nurseries of the state,
where we can get more absolutely accurate counts, 607,434 bushes have
been destroyed.

The rust investigators from the different states have observed
many interesting facts in the relationship of the barberry to the black
stem rust of grains this year. In some states every single infection
of rust investigated was directly traceable to barberry. As many in-
stances have been found where the barberries have begun to grow wild
in this state, we believe the campaign for their eradication was started

& SEVENTEENTH Report STATE ENtToMOoLocIst oF MINNESOTA—1918

just intime. The good effect on the grain growing industry can already
be noticed and it is hoped that adequate legislation will put the bar-
berry in its proper place with all the other huns.

A list of publications issued by this department, together with the
financial statement and the list of Minnesota nurserymen are appended.

Respectfully submitted,
A. G. Ruggles,
State Entomologist.

FUBLICATIONS

CIRCULARS
No. 46. Jan. 15, 1918, The Hiydrecy sinc Acid Gas Treatment for
the Flour Moth - - - - Washburn
No. 47. Mar. 25, 1918, Some Insects Injurious to the Potato - Graham
No. 48. Apr. 1, 1918, Spraying - - - - - Ruggles
No. 49, Apr. 15, 1918, Insects of the Home Vegetable Garden - Graham
No. 50, Apr. 20, 1918, Insects Injurious to Small Fruits - Graham

No. 51, May 1, 1918, Fruit Tree Cankers and Their Control -
Stakman & Newhall

QUARANTINE

No. 3. April.1, 1918, All Barberry (Berberis sp.) bushes except
the species and variety known as Japanese barberry (Ber-
beris thunbergii). - - - - - - - Ruggles

FINANCIAL STATEMENT
STATE ENTOMOLOGIST

PNG EOP tO Ue rae sbatece wocde, crea ny hee eas weireue oh So pkerae tates lores anaes $6,300.00
Expenditures

Galatta caren etn eae nesii cr ei tncs boinc Penson Sree y ecm Ratienne ease $3,741.30

ESpenise, amd: travielus. cer.» .tiis -tomtea<sielssievale sts = 324.17

Brnting: and publishing. 6: 5.--ac¢s0. ¢aa0s- + <5 909.71

@iiceestipplicsusyyn tic sie 6 ea oie wianeleee stereo cureees Se 59.06

peio lt aNGvEXpPHESS: sale oc vic slavele vie ducbesde eee ob ‘ 12252

RO GtAe) Une aiancan Gunso eleee Le bias wr aNel's vases a lepeae Sasa i 141.00

Telephone and telegrams Bec Kemer NG ORS NOE C 87.78

IPINGHOS, Gh, Siulesrenipnlesy, Cee sooousccccscenon 306.99

lEremiuoEe aol SOpbljomISiNs > 55ccc0e00b00n00c00006 342.34

IMbigelibvneemis' > Goehasc peop eenosedencacoe mye 373.22 $6,298.09
eal aT Ce eNO Svs ate cess ated olevac vate aheuck a oeaienalen domeisieaeaiie overs $1.91

NURSERY INSPECTION
December 1, 1916 to August 1, 1918

Bellamecs IDeeily IHG S eos osecase dus waco oowor $1,229.54

Appropriation, WIV oocasecocccn bo ce eueodes 3,000.00

Cr. from nursery inspection fees 5/9/18 ...... 20.00 $4,249.54

Expenditures

SHEPTON ae eee Ae $3,191.50

diraneclucnidmescp en Sem ce caravan citer smi citheue oe seeecers ie 883.51

Oicems ip plese tossed tecia stots chtcakl cont eis oe mute 3 28.60

TPYGYSUUEHE: | aw ea acne Ras OE NR Cen ECR 50.00

1 Dera SIONS? 4d que alewePe ce oe Re) HE A Ene ics 89.00

WitusedEbalancenlOlGal7 wae nose es eee 01 $4,242.62
Balance ne. mle ONS P ae owes ers esa ware cde sevens ere ayers et $6.92

10

SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOoTA—1918

Collections—Nursery Fees

Cashtonshand. December ONG, seeercice ee eee 15.00
98 certificates issued to nurserymen (1917).... 490.00
8 certificates issued to dealers (1917)......... 40.00
19 certificates issued to nurserymen (8/1/18)... 95.00
3 certificates issued to dealers (8/1/18)...... 15.00
Deposited with the State Treasurer:
1917
Deak Gee ines Meet cs crc tpt Bee ATEN Sheers farmue behest outs $30.00
WERE! Paatatteae teton Bote AAS Maven Nis Sine eae 10.00
JASSTEROISTE gy dae SO ho SRE SOG cs. i ee eRe 25.00
ENS pets trocers ater d eee haces cceuspe y Sreaees - 30.00
September se tn pica. cen ers crates gai is 70.10
© ctoberel4ge ree nn tances sca te aie Breet athe 65.00
Octo erg Ore Ay eek tenia ee Sole a eres 100.00
INioi yeaa etekelt/tess ey ocse acters ey sclera sisi eo stake lone ce 110.00
INOwemlb ety onn te. 1c tete se Meee ores tee nes 65.15
WEcemberal Owes. cis tees fe eo eusne 35.00
1918
Janay lO wad wee poet obsiicitie clube hie 5.00
Ma relies Oita ncestye atts copes ycsers ore raha icut sense eae 40.00
TANGO iW R27 ed Pe roeele beIeten te ott rt Caen peg 15.00
nA Feta NS) See eRe rec isis ee bie eas Coeeetene Bue ce 20.00

WHITE PINE BLISTER RUST

August 1, 1917 to August 1, 1918
August 1,1917; balance forwarded - 5... .%..5. $5.53

August 1, 1917, balance of appropriation .... 2,500.00
March 14, 1918, credit from 1919 appropriation 4,500.00

Expenditures
SEIMEI Oy Ga eR Sc A cee Ce ga Cnc eI a $3,069.01
Bacpense, anCmtravie ls sates cites cons ccm te 1,868.34
Printings ance publishine: serene tc acerca cer ae 104.50
Offices stp pltespanc. vss ote ere oo mar ace: 85.29
Mreiakt amdcexpnesSmre ance cet aeete tke coterie ave 25.57
Groceries and camp equipment ............. 304.67
BhOtOSs sCUES CEC: wae teed Hoala BOa tae tone Hiss 26.41
[bbanblboae: halal CCapbhyoenketne ga socsnGocosogKooac+ 679.48
| eh] BY oh psec Pape nee ar tant arch etre en CGN rR PER ee 554.80
Miuscellameois: &aatelgiaee ete toieas ces Sere ren he 81.98
Bia lata Ge es say wee eal estaacas eka ta aes Risvatevers mleteccuatenetcgaee ames

Expended on
Nursenieswandsleadsmansacctork corre nee pees $2,147.39
SCOT O Ee ee thio eek te SRG Gh Es, ieee canner boxe ee 2,414.02
He GACICA tO it Rua ick tes akon eee oe eee 2,238.64
MTS it ale acre SEAS Peete dcr re eds Seaela. Staite acheeenct Eee $6,800.15

$655.00

$655.257

$7,005.53

$6,800.15

$205.48

*Credited to inspection fees under 206 G. L. 1913.
*25c for collection charges on country checks.

Town

Allee ILGA coclgs ou
Nose ECEY Golgoacae
uibent Wea esc. 365%
llbentelueal a.a5 0%.
INIESEVTGKREY Sheonse
PATA OMe sve, Steves x

PANS Oita sti tcnetatiens
NEW teTines et e65 deals
PAWS ETI asses eee cage sal
PASTS td Tea ses tee aides ance
NTS Either se enenieets is
IBiaolengactyeccs care ac

Brelitralmaty ware ssp cicts ct.
Breimid Gti, oes. oS stkce
Brendes con bor
Byam meres Se erarer.
ISimariM@InGl gogo see eae

Byron

Canby

Gamitonasevervc ctor
Cloquet & Arago...
Cokatronsimswws ns
Cokatomus.cecee

WWelaniomedecyctak oe
Warsseltern a: cosas
ID@IEING sdemebaoodes
Bagle Bend .......
BastGrand Honks) os
East Grand Forks ...
1a COISOR Ese a pone
EexCelstOteaca. seis s15
Rexcelsiot eo. aes -
Excelsior
Excelstotmeeiiat = oe

Excelsior ries
Excel Stone ee:

CGambrideesy.5-5...

NURSERIES INSPECTED

SEASON 1918

Nursery Proprietor
soos Ing Alloys: Ibe, INTERSECTS 5 obo once O. M. Peterson
Tee Pp Minnes ota StateeNiULSeEynote a ae oe E. C. Eaker
Pee hem S Outi SIdem NiULSe vine e Martin Fridholm
Joo HGS INMMPSCATS 65 oe base de scece as Clarence Wedge
sooo MANIIeoxeNalings IME IRAP 556 ob0660m0oc W. H. Horton
eos Collesierotmhionestiyanrn eee State of Minnesota
soo ine YASIKGny INIMESCMPococotacuosaecob ods IBOlieds
Sere NEW ater eiGUdte sbatiboe se cena. esc roll Peter Peterson
Sho NAG AtICstE INMESENG Soe ocucosaueoe C. F. Woodle
soot Ne ING Jkcimemein, IinGsoo¢se0uo004 Austin Greenhouses
oo ihe turtle Creek Nunsenye --5o05 soe J. M. Lindsay
... Lhe Herschberger Nursery Farm
soo was Syveclneires INGPSSCAT.s socns codecs J. E. Swedberg
... *Johannessohn & Co. Nursery..Johannessohn & Co.
...*Beltrami Nursery & Greenhouses....Otto Brose
... George C. Berglund
Pee Wah-wal-taysees leodger-s. see T. W. Ingersoll
we netems Ane rickson
Ee hewmsivacome Niinsetyaae cine tee ce F. E. Cutting
aOshiurrdaswe Nites et yea ans oe eileen ae re N. N. Oslund
PAU SLVEHtS NURS Clnyar ci ciated sect ee aie Peter Sivert
... *Hillmore County Nursery........ George F. Snyder
ae Colles erormHonestinvey sas eee State of Minnesota
nee pe ckaman
a PTA OMT kl Oferta rem FoR cake sae oie aioe John Eklof
eee Cokatom Seriygehagiineer a eee elo: Fayette Lee
... Crookston Substation....University of Minnesota
TO CHUSteH hy NUESEE Va Mined ac eee E. W. Schuster
ie Shee Delano Nurses cece eae Charles Sell
na Wen. Herouson
ee Ce Ace Bntinkoiws
...*laylor’s Eagle Bend Nursery...... TP Wee taylor

Bast Grands honkcu Nise myers nee eeeine Oscar Wick
jibhne woudenback iNunsetye....) F. M. Loudenback
Roa cketiviNUnset yan soc rene ae sbe ree A. Brackett
.4.*Phe Deephaven Nursery......../ Alfred O. Hawkins
...*The Highlands Fruit Farm..C. P. Jackson Land Co.
ioe Dhe Hawkinson Nursery...) Charles Hawkinson
...*Minnetonka Old Fashioned Flower Garden......
Mrs. N. S. Sawyer

suo Wihisrer Iai IaveiilG ooandcadesaces bic J. K. McBroom
es ©} Eien Seamanese NiitSetye emis aoe ee O. H. Seaman

11

Town

EexcelSionen as nclnien =

iZ SEVENTEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—1918

Nursery Proprietor
ePhunmans. ¢Ntinseiryies siecle ee W. J. C. Thurman

Zumbra Heights (P.O.*University Fruit-Breeding Farm Nursery.........-

Excelsior)

EexcelSiom santos cern
IQenheneKOn ayo ncespeoe

Bainmonituccwmciiete « «
[RaibeanOinle Gon noo coo oe
tara auilities ci ciaie cole
Bamibattlitas peorscicres.-
Baribailite weaceeerieche
Barnibaulite se seceeeer

[Deavalnenslhe orc on 6 oda os
Farwell R. F. D. 1..

Bee pore caries os eye

Gandens@ity. ..5.----
Gilenwillley 2ens. a. aan -
(Grranibbike” Gage oouoode
ieilstad? hence tae or
elim Betepe sco s.cce Syovone
las tiyasmrtattse iv. ae
OTS tome sto ocr 2
owand sWakes....¢
International Falls ...
Cellini. ates foe eS
ISeniyonl: 5. sae 5,44:
IME. Ome S heeseneree oe ok
IMG MVOIl cua ere cl ee ©
Kimibenlyaieccnec es:
Warn@rescent ne ae.
Wa Crescent a. -45 4:
alee: (Gitys = weaelam a:
ake ACity (sack sooo.
Wakes Citys seem cicr

Eales Gity: Mya. hye ec
WalkkeaGity* < os7c.4o5 «
Walcelande 2). schema oe
Wamiberton! ++. .4u- 5.
ILsinalGiidohasl Ga gcemouc
lentchiirel dy yy... eet
Bonglake S220... -

Long Lake &

Minneapolis ......
Wons dale eae es see ae
TW VETINE® cs & erst or nose

University of Minnesota
*Zumbra Heights Fruit and Poultry Farm........
August Sauter

+The Commercial Nurseries of Fairmont

(CIVGalers)) gen. oso nee n eee ees O. B. Dokken
Amber uvakes NiurSetyecn cine moe P. C. Christensen
HH AaieIMOnt I NMGESeriess sane ees sie > oe G. D. McKisson
*The Andrews Nursery........ C. H. Andrews et al:
“[BMeIIN boa mielCOkn ogo tooo oueecuo so obo! A.M. Brand
*Farmer Seed and Nursery Co....... Wm. Kueker
{fhe Northern Nurseries Go. (Dealers)... ..22a..e

F. L. Gorman & C. J. Claybaugh

WioodmiG@rest aitaninmensrs semis ome @ Ho Smith

*Claus Osterberg

*The Wilwerding Nursery and Apiary .............
A. J. Wilwerding

eMinliismivakesiNiunserny aaa: ede aceon eee L. D. Mills
-HMlorals Mound INursery.-e- se «eee J. J. Peterson
*The Lake View Nursery.......... Victor Carlson
“Evergreen Nursery............< Rev. O. A. Th. Solem
HEiucharnts: Soms) Niunseiy seems. oer Hugharts’ Sons
Wright County, INursenys.cees ose: ae J. S. Elofson
Vine cate tlheNtirSenyaeas se cee: Wm. Sandrock

*Howard Lake and Victor Nurseries..W. H. Eddy
*International Falls Nursery..School District No. 4
I. W. Gehron

Kenyon NiurSery=m.um tae os J. A. Mogren & Son
‘bhe = OaleiGrove: INurseny.. cee oe P. HE. Volstad
‘ihe southWwenyon iINunserynoe ae E. J. Hershaug
TAvGesyaackwbutre INUGSeryacies asco H. B. Ayres

Sunnyside thrnuit Harnis2 sce scc-ee ae eS ea blarris

H. Vollenweider
eN: Be Anderson eNurseryes.- sees N. E. Anderson
*The Jewell Nursery Co........-.- J. M. Underwood
{lhe Johnson Nurserpy.s.......0-..0- P. G. Johnson,

3300 Elliott Av. So., Minneapolis

* National Nursery (Coven aasssaee J. L. Anderson
sMollesonm Nursery: (Cons eaaceeees a. G. A. Anderson
*Maynheld Nursery s..-..: L. L. May & Co., St. Paw
The Motter Nursery.tsc..se. .o- Julian P. Motter
*The Chisago Lake Nursery..... Ludwig Carlson
*The Bergusom Nursery... a.c. oso. W. C. Ferguson
*The Daniels Nursery........... Franc P. Daniels
Jiohn Ee Erte Nunsenyacges- es 1. . John H. Hirt
HPonsdale Nursery. seater shies: John P. Vikla
KS UVErMes NUGSELVs aa pitie saeicrie oc sroc ss C. E, Older

NurRsSERIES INSPECTED SEASON 1918 13

Town Nursery Proprietor
MIGNOGI tes Woogie ee Gomes R. Spande
Vitaliy elles acento eh cheat hes O. L. Christopherson
IMIAGHIBOM ctoocosceda0d “hes MadisonsNunsenyss. oes 2. stn Sas M. Soholt
MifamikcatOMscne ec cistee cies UMaine) ~ INIDIPSEIAZ5 ogo usp ebauoconooe Ik 2. ~Siaayitiln
IMiamikkca toMy itr sisters.cyare «chars +M. M. Sinotte (Dealer)
Mantorville? 5320... 20'. *“DodgsexCounty (Nursery...) ces se. W. E. Fryer
MlsiaS neil oebes.ceo oro ote of > Minnesotay state NUnSenye ees one sence lt Cy Baller
WIEN Sou abeaceueee “Orton PankewNunsenys ayes. stot vee Ca Orton
IMiedioOndy aan tice =e sens “iike, Medtord yNunsenry...- 4 Grace Patten Eaton
IMiedittondiies armie sce sens Dae IDeerane@lial INieSEAYS oca6scses000~ L. A. Schoen
IMIMNGIF@GL Gd sos coco oo ued C. B. Finsaas
IMbTOAEZVOVONNIS Gooccoaoce alee, ichalllbhn IByealkeres oo 55 4629 Lake Harriet Blvd.
MIGTNEEOOIIS sogopssoce *Board of Park Commissioners........ Court House
Mitninveapolis) sacs ace a +W. H. Bofferding Co. (Dealers) .7th St. at 2d Av. N.
Minneapolis seers: *Cedar Hill, C. N. Reudlinger, St. Louis P’k, Bx. 114
Minneapolis) ss. 4.14. Tier armer sNUTSer yc neon oo ele i oe
E. A. Farmer, Linden Hills Sta.
Mirnimeapolistescereie ce = (Ca. sbiantere yw rcnacte seiko hee 5700 Nicollet Ave.
Minneapolis ees. ae. WNorthnupytimes sion tWealers)s 4 eine oo ae
Ist St. and Hennepin Ave.
IMiminleapoliswenm anise. *Rose Hill Nursery, John Hawkins, Como and Eustis
Minnie ota takin .s dots sc mil eiolandes# Nise tyres seas ade nee J. L. Teigland
Montevideo! ...5...... INGE Warez IBirwike IMEI. 6oonoansoocoe- M. Oleson
IMromiticelllonensnneinee ice MonticellogNurseryastics.oa0-8 eee — Bateman
INI@mme VCP Sipee 6 ohigeiend sie *Combercroft Farm and Nurseries, G. E. MacComber
ING WiiStewtiey a cene nee oie Nevis Fruit Breeding Station....... Jas. Arrowood
NIG leiefeleytorn Gonoues “balkkeside Iopiltiny arin, .odacc0cccaance Ee tip
INIERSADO NS Sea a a erecideeia oe PUPlae Isenilesy IN(WESEmMRS oo 6 o00codccon dss J. V. Bailey
INiewan Wilts k ones HPioneeriNussenyCoOs.4..nacee Wm. Pfaender, Jr.
INGISSWVid, Geo it sic saree koe *Lundborg Bros. Nursery
iINorthitield( y. sese aon The Northfield Seed and Nursery Co. ............
P. M. Punderson
INOwSteeaulner ascends Nos Sts Paul-Horticultural Parmos.. ooo. J. K. Dixon
@linlah tea ctossh coat shew Dunsmore, Nursery: 3... .....<9. ot Henry Dunsmore
OMA a ese ae fara sesh wets ‘hen Weise a Niinseiya is eee eerie ee Oliver Wyse
Owatonname sere en *The Clinton Falls Nursery Co...Thos. E. Cashman
OWAUOMME ocobooausoor “he sMiiitchelllsNursenyevtese eee D. M. Mitchell
Owatonnase eee ee ‘Owatonnay Nursery ‘Cou. ayosene oa. L. J. Wesely
Ban ales valllenesamnes eles “The Elmwood Select Nursery.. Frank Brown & Son
ena aiivncc its ceptors cre & Ja eae Batter
ine Citys a o0 See cco oc Minnesota Northern Nurseries....... O. J. Graham
RESEO Ml nay naire ois AMG IPrSsitorn INKESCIAYS 5 oon acco peauae C. E. Snyder
IBGINCetOMe ns wears. ses Eee lowell
RrinicetOne nese ase Jer OFeRinsten
IROCHES tet asics ols Evergreen Lawn Fruit Farm...... H. W. Harrison
ROGkMOrd Ga. c.éc.c00 on - (ihe wakes SarahmSpecitalityasharm rh Cam nelcel
RuGhyGityas o5 his ec cen Phen ahan KeilllimernseN tes ety Conner R. E. Killmer
St4@loudimeeycs eee +The St. Cloud Nursery Co. (Dealers)

Sts Hilaire merey./..,..0 26%. 7 Park sRid ten NiInSeiy wee meni oe S. J. Amble & Son

14 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESoTA—1918

Town
Stdiames 5 aoann ties ses
St lOSe pln accisets
Ste Panties + sets ouch

Steal eee 8 sea cone

Style atl Sete ia tere. ears
Sita wcatua ete serch ons

Aye ART ao nee ee
Stayt tears or. eta crerncede ole
S Cala tila tee o eae

SS ae erat earn erates operant
Stbeten recente
Sacred Heart =... %...4.
Starbitelke 5 os hoheteeaes
Springs Valley j1 55.00
taylors Walls pense cr
APS dl (Sie acne ene Bio Sic
AAS fede kis Dep Dn oe a

WWilasyizaltaientn stern sibs) cers
Whanyezaltale kr cera eitain Mest vs
Wayzata sscrrste x 233
Witte sBiear, asiere .c ele
WVsinine bag Onateee ciara:
VWinnebac of cn mncee o.
Wiest Goncordis. =...
Wni@inby ne se dopios aes

Nursery Proprietor

"Ste James Nurserweneac.s toc tose nae Ie Ve deel!
Matthew Reinsinger

CE Am mundsoneNursenye sss. anes eee ete

C. E. Ammundson, 1960 E. Minnehaha

“h CaBe AurdenssonmNansetiye weit eee re atte

J. C. B. Andersson, 1285 Portland Ave.
*+Emporium Mercantile Co. (Dealers) 7th and Robert

‘Hoyt landscape, Nurserniesus sane one iene eens
W. T. March, Hoyt and Hamline Aves.

Kallimectse Northern Nurseries a. acento eens
E. C. Killmer, 1511 Raymond Ave.

ne wPankcaiNarSenies ess. acces Poe eee ee
Holm & Olson, Inc., 20 W. 5th St.

Rainbowa Gat demsn. s,..5 stes.< tose eee oe ae
John S. and Grace Crooks, 1980 Montreal Ave.

*Riverview Gardens..A. J. Wilkus, 909 Winslow Ave.

*Nicollet County Nursery....... C. Edwin Swenson
+ Sacred! ddieart, Nursery. oo. ..-- J. Flagstad & Sons
*Minnewaska Nursery............. Paul J. Klevann
Spring? Valley, Nursery... 0a.40c44- Frank Waskosky
ESitramdasw Nitiisetsyal ewer aoe odie G. W. Strand
Althea diver gINUIESE iyi. selene ae cea oe J. P. Eriksen
*E. L. Thomas & Son

*Miaplehitnst Nunsety. «2... oasee Grace E. Kimball
“ihe-Cabinwood sNursety....o.00o. S. J. Wetherald
*Herodowill Nurseries... .. sce. F,. X. Ferodowill
*The Minnetonka Nursery......... Douglas Winter
A. E. Hooker

*The S. D. Richardson Nursery....S. D. Richardson
dihes Winnebago. Nurmsemyemnnaense meas dee — Peck
* West Concord Nurs ety sees ace Fred J. Cowles
*The Pfeiffer Nursery......... C. A. Pfeiffer & Son

*Nurseries holding certificates 1919.
+Dealers holding certificates 1919.

LIE SaISTORY OF AN OAK MWIG GiIRDLER*

Agrilus arcuatus Say and var. torquatus Lec.

By A. G. RUGGLES

In August, 1914, my attention was called to the blighting of the
oak leaves on the University Farm Campus. The leaves attached
to the tips of the twigs wilted and died as if struck by a blight. Upon
investigation it was found that the damage was localized, being con-
fined to a comparatively small area around the Twin Cities (St. Paul
and Minneapolis) and extending to Stillwater on the St. Croix River.

In studying the damage closely a small buprestid larvae, evidently
belonging to the genus Agrilus, was found burrowing beneath the bark
at the tip of the twigs, causing the death of the part beyond the bur-
row. In looking up the literature it was found that in California
Agrilus politus Say? performed a similar operation on a species of oak
there. No other reference was found to any other insect behaving in
this manner, and hence in our notes we referred to the species as
Agrilus politus. It was not until June, 1916, that adults were obtained
and identified by Dr. Schwartz of the U. S. Bureau of Entomology as
Agrilus arcuatus Say and variety torquaius Lec.

The life history of the insect has been followed very closely for
four years, notes being taken at short intervals for the first two years
and at longer periods for the last two years. Beyond a doubt it is the
worst pest of black oaks discovered in recent years. R. N. Chapman
in the Journal of Agricultural Research, Vol. III, No. 4, Jan. 15, 1915,
published, ““SSome Observations on the Life History of Agrilus biline-
atus Web.” A, bilineatus and A. arcuatus work in the same species of
oak—but particularly Quercus rubra L. The former attacks the trunk
and larger limbs while the latter attacks the tips of the branches and
works downward, often cutting off branches eight feet long. These
two Agrilus species threaten the extermination of the black oak group
in the part of Minnesota above indicated, A. bilineatus attacking from
below and working upward and A. arcuatus attacking at the end of the
twigs and working downward.

1 Published, with the approval of the Director, as Paper No. 169 of the Journal
Series of the Minnesota Agricultural Experiment Station.

2,Cal. Hort. Com. Mo. Bul. Vol III, No. 3, p. 150.

15

16 SEVENTEENTH Report StaTE ENTOMOLOGIST OF MINNESOTA—1918

LIFE HISTORY

Aputts. The first adults of Agrilus arcuatus and var. torqua-
tus were taken July 1, 1916. From that time until July 27 several
hundred were observed. july 7 to 15 seemed to be the week in which

they were most abundant. - During this time they were observed

Fig. 1. An oak leaf eaten by adults of the oak twig girdler.

feeding and sunning themselves on the leaves. In fact the habits of
this species were very similar to those of A. bilineatus mentioned by
(Chapman, with the exception that instead of alighting on the bark to
sun themselves they invariably alighted on the leaves. Numerous pairs
were seen mating during the week of their greatest abundance, and on
July 18, under insectary conditions, a bronze colored male A. arcuatus
was seen to mate with a copper colored female, A. arcuatus var. tor-

quatus.

Lire History oF AN OAK Twic GIRDLER 17

Eccs. The eggs are usually laid singly on the side of the twig
near the terminal bud. Sometimes they are laid an inch or more from
the terminal bud on last year’s wood, as shown in Fig. 3 of Plate I.
As soon as laid, the egg spreads out like a little pancake and adheres
firmly to the bark. These have been taken, still sticking securely to
the bark, two years after being laid. The eggs hatch in about ten
days. When first laid they look like a small flattened piece of green
gelatine. They soon turn brown and after hatching the shell becomes
gray.

LarvaE. First instar. When hatching the young larva makes its
way out of the eggshell directly into the bark beneath the egg. Newly
hatched larvae were first found July 24. The larvae immediately begin
encircling the twig beneath the bark. By August 7 trees all over
the cities showed signs of infestation. As
the burrowing continued more leaves were
cut off. Often the burrowing continued to
the junction of the original twig with a
larger branch and around the larger branch
thus cutting off the nourishment from all the
twigs above this burrow. Consequently all
the leaves on the upper part of the larger
branch soon died. Thus one larva was re-
sponsible for the dying of many leaves.
During the rest of the month of July and
in August and September of the first year
the larvae confine themselves to the cam-
bium layer. The burrows at this time were
of uniform diameter and the head measure-
ment of the larvae was 0.375 millimeters.

Second instar. In May and June of the
next year the larvae still confined them-
selves to working just under the surface
bark. The head measurements at this time
averaged 0.47 millimeters.

Third and fourth instars. The larvae
were actively at work during July, August
and September of the year following hatch-
ing, for the most part burrowing in the
centezwotethe twies, lo’ the middle of

- Fig. 2. The bark on an oak
USS cMemieade measurements averaged (hy 2A et ane sa anne ea

07 millimeters whileatter that'date they — wavgre: tanvae (tm thet: bur.

18 SEVENTEENTH Report STATE ENTOMOLOGIST OF Minnesota—1918

Fig. 3. An oak tree showing dead limbs killed by the oak twig girdler.

measured 0.75 millimeters, which is the head measurement of the
mature larvae.

During October many of the larvae began coming out from the
center of the twig and encircling it just beneath the bark. Burrows
five and six inches long were often found before this occurred. Often
the side branch on which they were working was not long enough and
the encircling of the branch would take place on a main branch. Note

Lire History oF AN Oak Twic GIRDLER 19

Fig. 4, Plate 1. The following year, therefore, this larger branch would
die. One such branch measured an inch and a half in diameter and
was eight and a half feet long.

PupaE. By May 1 of the second year following egg laying the
larvae were found in the prepupal position. By June 1 practically all
found were pupae.

As this life history seems rather unusual, the notes of 1914, 1915
and 1916 were supplemented by notes for 1917 and 1918. In August
and September, 1918, many red oak trees again showed signs of serious
infestation and hence the life history as given is certainly correct for
this part of Minnesota.

PARASITES

Parasitism on the larvae of the species was quite evident. At ten
different times, the first time just a year after egg laying, parasitic
hymenopterous larvae and later, pupae were taken in the burrows of
the twig girdler. The reared adults sent to Mr. S. A. Rohwer of the
U.S. Bureau of Entomology proved to be a new species of the genus
Tetrastichus.

CONTROL

Obviously this twig girdler is a difficult insect to combat. The only
possible control on large shade trees would be to trim all small dead
branches from the trees and burn them with their insect contents. The
odd or second year of the infestation these dead twigs stand out very
prominently over the tree and can easily be cut. The labor expense,
however, in such a project is practically prohibitive. Twenty-five hours
were required to prune one red oak, five feet three inches in circum-
ference, thirty-nine feet high, and with a spread of thirty-four feet.
The work on this tree was done so successfully that in the next infes-
tation year it was not nearly so badly damaged as others in the neigh-
borhood. To be really effective, all the affected trees in the neighbor-
hood should be pruned. It is possible also that spraying the trees with
bordeaux mixture or lime sulphur would act as a preventive as in the
experiments with A. bilineatus. In any case it is a community problem.

20 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Helen A Sanborn ,del

PLATE I

Fig. 1. Adult of A. arcuatus. Fig. 2. Adult of A. arcuatus var. torquatus.

Fig. 3. Egg shown in position on an oak twig. Fig. 4. diagramatice view of a larval
burrow. The figures represent the comparative length of instars. 4b shows the
way a burrow is often continued.

POTALTO-SPRAVING IN MINNESOTA

By S. A. GRAHAM

In the past, it has been the custom of the Division of Entomology,
in testing insecticides, to carry on the preliminary tests on small plots
at University Farm and if these proved satisfactory, to make tests
on a larger scale in co-operative experiments with farmers in different
parts of the state. For several practicai reasons, this system of leav-
ing the final tests to farmers, even with careful supervision, has not
proved satisfactory. Since tests on a large scale are absolutely neces-
sary in order that questions may be intelligently and authoritatively an-
swered, and since there was not sufficient available land on or near
University Farm for such experiments, it was decided in the spring
ef 1918 to try a modification of the old co-operative scheme for the
potato spraying experiments which promised to avoid most of the diff-
culties encountered in past seasons.

The greatest difficulty in the past has been to get the materials on
the plants at exactly the proper time and in the right way, particularly
since most of the experiments were located at some distance from the
Station and often in more than one locality. It was also difficult or
impossible to get comparative data on a number of different insecticides
under the ordinary co-operative agreement. From past experience it
seemed advisable to keep the following points in mind.

(1) All spraying and mixing of materials should be done by
someone connected with the Experiment Station and not by the farm-
er. (2) All observations should be made by a man connected with
the Experiment Station. (3) The spraying should be done with a
standard type of traction spraying machine which should be available
at a moment’s notice. (4) The spraying experiments should all be
located in the same locality, preferably on land owned by a single
person, and readily accessible from University Farm.

After some searching, a suitable location was found and the fol-
lowing verbal agreement was made with the owner of the farm.

The owner agreed to:

1. Plow and harrow the soil and plant the potatoes in three foot

rows.

1 Published with the approval of the Director as Paper No. 158 of the Journal
Series of the Minnesota Agricultural Experiment Station.

21

22 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

2. Cultivate and perform all necessary operations throughout
the season, with the exception of spraying.

3. Allow authorized representatives of the Experiment Station
to come onto his property at any time for making ob-
servations, spraying or collecting.

4. Furnish a team for use in spraying, whenever it was deemed
necessary by the man in charge of the experiments.

5. Furnish water and a place for mixing materials.

6. Furnish a dry storage place for the insecticides.

7. Keep the man in charge of the experiment informed as to the

dates when digging was contemplated, so that he might
be present to record the yield.

The Experiment Station agreed to:

1. Furnish a suitable machine for the work and keep it in repair.

2. Furnish all insecticides and other spray materials.

3. Mix and apply the materials when necessary.

4. Use no materials on a large scale except such as had been
given preliminary tests and had shown promise of suc-
cess.

5. Keep all records and be responsible for all observations.

This agreement fixed the responsibility and made clear to each

party his duties in connection with the experiment.

Under the old system of co-operation, it was impossible to run a
series of experiments on the same farm, using a variety of insecticides
side by side, since the farmer very naturally was unwilling to spend
the extra time and trouble in spraying that such a set would necessi-
tate. Since it is impossible to accurately compare results when plots
are on different farms or even more difficult when they are located in
different counties, the confining of all the potato spraying experiments
to one farm was exceedingly advantageous.

Potato INSEcTs OCCURRING ON THE PLOTS

The plots selected for the work were well supplied with insect
pests, altho no disastrous outbreak of any species was threatened.
The adult colorado potato beetle, Leptinotarsa decemlineata Say, was
very abundant in the spring. The potato flea beetles, Epetrix cucu-
meris Harr., and the leaf-hoppers, Empoasca mali Le Baron, were the
other primary pests. In addition to these insects which were of
primary importance, the tarnished plant bug, Lygus pratensis Linn.,
and several other bugs were common.

Porato SPRAYING IN MINNESOTA 23

MATERIALS TESTED

The stomach poisons tested were:
1. Lead arsenate.
2. Zinc arsenite.
3. Calcium arsenate.
4. Paris green.

Each of these poisons was applied with and without bordeaux
mixture.

The contact insecticides used were:

1. Nicofume.
2. Black leaf 40.
3. Nicofume oleate.

These materials were all applied with a four row traction sprayer
equipped with a “bordeaux” boom which sprayed from the sides as
well as from above, using three large chambered nozzles to the row.
The pressure was kept at about seventy-five pounds. At this pressure
fifty gallons of liquid was required to cover an acre.

ARRANGEMENT OF THE PLOTS

Three fields having a total acreage of about twenty acres were
available for this experiment. A little less than one half of the total
area was planted with Early Ohios and the remainder with Rural New
Yorkers. Since early potatoes as a rule seem to suffer more seriously
from insect attacks than the later varieties, and since the Early Ohios
were planted all together on a fairly uniform piece of ground, these
were selected for the most intensive work. In the case of both the
early and late varieties, the fields were divided into plots. These plots
varied somewhat in size according to convenience. Each material
was applied to two or more plots in the case of both early and late
varieties, so as to eliminate as far as possible error due to soil varia-
tion.

STOMACH PoIsoNs

The first set of arsenical sprays was applied to the early potatoes
and to the late potatoes adjoining them on June 13 and 14. At
this time, the plants in the early plots were eight inches high while
those on the late plots were about six inches high. The adult potato
beetles had been present on the plants for a week or more. Eggs were
observed for the first time four days previous to spraying. None of
the eggs were observed to have hatched at the time the first spray was
applied, altho it is possible that some newly hatched larvae had

24 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

escaped observation. At this time the potato flea beetles were quite
abundant and it was primarily for this insect that the bordeaux mix-
ture was used. The water used in all the experiments was a natural
soft water from lakes nearby. [Everything that went into the tank,
including the water, was poured through a fine wire strainer. As a
result of this care, combined with the fact that large chambered noz-
zles were used, and that the machine was washed out after each day’s
work, practically all nozzle trouble was eliminated.

The weather at the time of spraying was dry and clear with a hot
sun. There was a light breeze from the west and south. The weather
continued dry for several weeks following spraying so that the poisons
were not washed off the plants, thus giving opportunity for maximum
efficiency of all the poisons used. Under these ideal conditions, the
effects of the various poisons on the potato beetles were remarkably
uniform. Before spraying, the adult beetles were abundant in all parts
of the field, and plants on which eggs were found averaged seventeen
to each row. One week after spraying the adult beetles were remark-
ably few in number and less than three plants in each row showed 1n-
jury from larvae. These rows were about sixty rods long.

Thus it would appear that all four of the poisons tested in this
experiment were equally effective under ideal conditions, so far as the
potato beetle was concerned. The dilutions used were two pounds to
the acre, or four pounds to each one hundred gallons of liquid, in the
case of lead arsenate, calcium arsenate, and zinc arsenite, and one
pound to the acre, or two pounds to one hundred gallons of liquid
in the case of paris green. Each of these materials was applied both
with and without 4-4-50 bordeaux mixture. All of these materials,
including bordeaux mixture at the dilutions used, appeared ineffective
as a poison or deterrent for the flea beetle adults.

The second spray was applied July 1. At this time the vines had
doubled in size, leaving a large unpotsoned surface on every plant.
There were, however, so few potato beetles present that it is probable
the average grower would have considered the field “bug free,” and
would not have deemed spraying necessary at this time. There were
enough beetles present, however, to form the nucleus of a consider-
able infestation if permitted opportunity to increase unchecked. This
possibility was illustrated by a field on another farm just across a
railroad track from the experimental plots. This field was later quite
badly injured by beetles altho it was comparatively free at the time
the above observations were made. Materials were used at the same
dilution for this as for the first spraying. The weather was warm and
dry, making conditions again ideal for the maximum efficiency of the

Potato SPRAYING IN MINNESOTA 25

sprays. One week after this spraying, it was difficult to find any
plants on which the beetles were working, except a few at the edges
toward adjoining infested potato fields. The late potatoes adjoining
the early variety and a small block of a little more than an acre, des-
ignated as block No. 2, were also sprayed at this time. The beetles on
these plots of late potatoes were even less abundant than on the early
plots and the control was almost perfect in each case.

The remaining block, designated as No. 3, was not sprayed for
the first time until June 29. At the time of spraying a few larvae
had hatched but for the most part, the eggs were still unhatched.
Adults were abundant. On this block three poisons, paris green, lead
arsenate, and zinc arsenite were used at the same rates as in block 1
with almost perfect control in each case. This block was sprayed
again on July 23, altho the beetles were not numerous enough at
that time to make the treatment commercially profitable. Those pres-
ent, however, were well grown and so a heavy dose of two pounds of
lead arsenate and one pound of paris green per acre was used. This
spraying almost entirely exterminated the beetles in this field.

From this series of experiments it is evident that lead arsenate,
paris green, calcium arsenate and zine arsenite are equally effective
against the colorado potato beetle under favorable conditions of
spraying. Since this is true, the factors which should determine
the most desirable of these insecticides to use in potato spraying
are power of adherence and cost. Since it is a very difficult mat-
ter to determine the comparative power of adherence of insecticides
in the field, this was determined by laboratory experiments.

PoweErR oF ADHERENCE

In the determination of the comparative power of adherence of
arsenicals, considerable difficulty was encountered in devising sat-
isfactory methods of measurement. Two satisfactory methods
were finally worked out. Both of these methods were used, each
serving as a check on the other. The first was as follows. The
materials were mixed with water as for field spraying and a meas-
ured amount of each was placed on clean microscopic slides and
allowed to flow evenly over the entire surface. These slides were
then dried at room temperature in a dust-proof cabinet for 48
hours, after which they were carefully weighed. They were then
fastened in a vertical position and sprayed with water delivered at
a uniform pressure from a spray nozzle. Each slide was placed in
the same position and the nozzle was clamped in place so that each

1918

SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA

26

S

eed se
re PE Hees Bisias

" BE Bs a ety EE, i
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igi S

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eee ge
seams

of

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Aa BE eH Be
[eT EE
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8 eeeareve

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ae

Porato SPRAYING IN MINNESOTA 27

slide received as nearly as possible the same intensity of spray. The
slides were washed for from two to six hundred seconds, dried and
again weighed, cleaned and weighed a third time. From the figures
thus obtained, the percentage of the material washed from the slides in a
given time was computed and a curve constructed for each material.
At least 5 points were determined on each curve and each point was
the average of five slides washed for the same length of time.

The results of this series of experiments showed that of the in-
secticides used, paris green washed from the slides most readily,
100 per cent being washed off in ten seconds. The other three materials
resisted washing much better, zinc arsenite losing about 98 per cent,
lead arsenate 91 per cent and calcium arsenate 88 per cent in 600
seconds.

These results showed that of the four materials used, calcium
arsenate has the greatest power of adherence to glass. Whether or
not the same ratio would hold good on leaves, was open to doubt. To
check this point the second method was used. Geranium leaves were
used in this series of experiments.

The materials were mixed with water as before and placed by
means of a medicine dropper upon the leaves. A measured amount of
the liquid containing the arsenical was placed on each leaf, being care-
ful that none ran off. In this way approximately 4 milligrams of
the desired arsenical was deposited on each leaf. Ten leaves were
used for each material. After drying, these leaves were washed for
5 minutes under a uniform spray. Later they were digested with
sulphuric acid and their arsenic content determined by the Gutzeit
method.” The results are shown in Table 1, tabulated in terms of the
arsenicals used.

AWANIBILIE, Il

Milligrams Percent Coefficient of

left after washed adhesion to ge-

washing oft ranium leaves
Galciim»peansenate sce oe ae ee 3.0 25 74
Weadmanrsenateme sees ce acer: 25 On, 62
ATI CALS CMe sien ss Oo aero nis 2.00 50 50
Paleise eaneeun ina peed Haat So cero 0.04 99 1

The range of experimental error is greater in using leaves than in
using glass slides, but the results from these two sets of experiments
are so comparable that it is safe to assume that the same ratio of ad-
hesion holds good in each case.

2 Scott—Methods of Chemical Analysis.

28 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

COMPARATIVE Cost

The cost of an arsenical cannot always be accurately judged by
its price per pound since the different materials used as insecticides
do not contain the same proportion of arsenic. Table II shows the
approximate proportion of arsenic contained in the four poisons treated
in this article.

PA BEE LT
Arsenic content in
terms of AS, OF
Per cent
(Cailontiine ranehioe a petomniaes Ae, alo GEOR Bee ob boob er muon 42-52
Keacieatseiaceye es hehe cr eo eee ne Sine ct eos horeka tc Jake 30
ZAC MANS EMIT ROE, HER Mote be Pe SO ne eee one 40
PaAriSe SHEET swans oor oo J onion a Ln 58

From this table it is seen that paris green contains almost twice
as much arsenic as lead arsenate. Thus it follows that to do the same
work, lead arsenate must be used at almost double the strength of paris
green. If paris green sells at 70 cents a pound and lead arsenate at
35 cents, the cost of the arsenic would be about the same in each case,
altho the arsenic in paris green would not be worth as much as that
in lead arsenate, owing to the difference in power of adhesion. The
same comparison may be made between lead arsenate and calcium
arsenate or zinc arsenite.

Since calcium arsenate usually costs the farmer about 5 cents
less per pound than lead arsenate, it is by far the cheapest arsenical on
the market. When its high power of adherence is also considered
it stands far above the other materials for potato spraying.

There is, however, one very serious objection to the use of calcium
arsenate for general spraying. Calcium arsenate as sold for insecticidal
use has a tendency to burn tender foliage, due largely to soluble arsenic
contained in it. This difficulty will undoubtedly be overcome even-
tually. It is perfectly safe, however, to use calcium arsenate on potato
vines, since there is not so much danger of burning as with paris
green.

CoNTACT INSECTICIDES

The only contact insecticides used in this series of experiments
were nicotine compounds applied both with and without soap. These
were applied July 9, when the leaf hopper nymphs were most abun-
dant, since it was thought that at this time they would be more easily
hit than when in the adult stage. The results of the field experiments
were not by any means conclusive in themselves, but when considered

Potato SPRAYING IN MINNESOTA 29

together with results in the laboratory, they throw some light on the
problem of leaf hopper control. The results may be tabulated as fol-
iows: The numbers in the per cent killed column represent a com-
parison of the number of hoppers on the sprayed plots with the
number on check plots. An estimate of the average number of hoppers
per plant was made by counting those on one plant in each thirty feet
of each row and averaging for the plot.

TABLE III
Per cent killed
ee Nicotmmesn|=500eancdissoape lilbys topo Omcalaa- meer: 65
Zee NiConimmen ol -o00mawithotiiesOapmec cect cece ac 17
Sh Niece OlOAwS IWe500) Gooucuonooseoocsccuusacgoends 3
AL Nii@oimne Glen ISSU0) Sktucoomoboccooooccsosbe dbo: 4
5.) Black leat 407 1-500 and soap 1 Ib: to 50 gal... 2... 13
Gung blacksleared (ml 5 00 nwathoutssOapeecde meee n eee 6

From the above table it is evident that nicofume with soap was
the only material giving even partially satisfactory control in the field.
Since those results were not sufficiently clear cut to form a safe basis
for any conclusions, it was deemed advisable to test the same materials
under carefully controlled laboratory conditions to determine their
comparative toxicity to leaf hoppers. On account of the difficulty of
handling the adults, well developed nymphs were used. Leaves, each
with six or more hoppers, were placed in individual vials closed with
cheese cloth. As soon as possible after collection, each leaf was re-
moved from the vial with the leaf hoppers clinging to it, quickly sprayed
with the desired material, and placed in a small cheesecloth cage. A
few leaf hoppers were, of course, lost in this operation, but enough
remained for the purpose of the experiment. The spray dried from the
leaves very quickly in the cheesecloth cages thus imitating outdoor
conditions as nearly as possible. The morning following treatment
the cages were opened and the results of the spraying were recorded.
As a check, leaf hoppers were sprayed with clear water and placed
in cheesecloth cages. Without exception, 100 per cent survived this
water treatment. The nicotine compounds were all used at the rate
of one part to 500 parts of water. In order to determine the influence
of the kind of water used in mixing the spray materials upon the
effectiveness of the spray, each material was used with distilled water,
water from Parker’s Lake, and tap water. The results may be
tabulated as follows:

30 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

TABLE IV
Material Per cent killed
Dist. Parker’s Tap
water L. water water
IN GievoliyihaaXen(o} (echtcmiaetaess ecioeeionac nics eitoe aero 75 74 50
Nicofume oleate and soap 1 lb. to 50 gal. ..... 96 100 97
Nicofume oleate with 1% kerosene emulsi-
fT Cetneeera te crace meh Hoe eae ee 67 73 59
mN COMM ney so coca olga ie eae ache ache soteecake ous 48 61 715)
“Nicofume” and soap 1 Ib. to 50 gal......... 100 100 96
SNicotume: and» soap lialb, to 100 gala. -.. -- 80 91 79
lake ean, 4 0ee en soree inn Acca esata tetey nents 58 4] 48
“Black leaf 40” and soap 1 lb. to 100 gal...... 99 er a
“Black leaf 40” and soap 1 lb. to 50 gal....... 100 96 100

From these results it would appear that both nicofume and black
leaf 40 with soap are effective in killing leaf hoppers, but it is also
evident that the insects must be thoroly wet with the spray if the
results are to be most effective. The fact that such a small proportion
of the leaf hoppers was killed in the field experiments was probably due
to the fact that many of the insects were not hit. Altho three
nozzles were used to each row, the under side of the leaves was not
at all thoroly wet. Thus the fault would seem to lie with the mechanics
of application rather than with the insecticide.

From observations in the field and in the laboratory the amount of
nicotine necessary to kill a leaf hopper in either nymphal or adult
stages, is certainly not greater than that required to kill the potato
aphis, since individual aphids accidentally included in experiments
have frequently come through alive, while the leaf hoppers subjected
to the same treatment have all been dead. It seems almost certain,
therefore, that if a tobacco extract with soap can be applied in such a
way as to wet the leaf hoppers thoroly it will be effective in
destroying these insects. Soap, however, seems essential to the suc-
cessful use of these materials, giving the spray liquid the proper
physical characteristics for maximum effectiveness,* as well as adding
a toxic action of its own. For maximum effectiveness, this would
necessitate the separate application of the contact insecticide, or its
application in mixture with other materials not of a strongly alkaline
nature, since a strong alkali would destroy the soap, thus reducing the
value of the tobacco extract. This would preclude the use of these
extracts with bordeaux mixture. On the other hand, they could be used
with lead arsenate, paris green, or zinc arsenite; since the soap solution
would not be destroyed by these compounds. The addition of soap

3 Moore, Wm. and Graham, S. A.— Physical Properties Governing the Efficacy
of Contact Insecticides. Jour. of Agric. Res. Vol. XIII No. 11, June 1918.

Potato SPRAYING IN MINNESOTA 31

would keep the arsenical in suspension for a longer time than would
otherwise be the case, would help to distribute the material over the
leaves,’ and would possibly improve its sticking power. It is doubt-
ful, however, if soap could be used with calcium arsenate, owing to the
excess of lime usually present in that material.

In the field experiments this season, the spray for leaf hoppers was
applied when the nymphs were most abundant. It was thought that
this would be the best time since the insects would then be less able to
jump and fly ahead of the machine. This spraying would probably
have proved effective if the under side of the leaves could have been
thoroly wet with the spray. But, as was pointed out before, this
was impossible with the machinery used. Delaying spraying until the
nymphs are most abundant has the decided disadvantage of withhold-
ing the treatment until a large part of the leaf hopper injury has been
done. These two facts coupled with observations of leaf hopper
adults flying into the spray and falling to the ground in a stupified
condition suggests the possibility of spraying when the adults first
appear on the vines in the spring and driving them through the spray.

In summing up the possibilities for satisfactory leaf hopper con-
trol, it appears that the tobacco extracts when used with soap are
effective in destroying these insects. The present mechanical methods
of applying these materials, however, are faulty and future efforts
should be directed toward improvement along this line.

4 Stokes law—V=2R2+(S—S’) ¢
ON
V=Velocity of settling. S=Specifie gravity of solid. S’=Speceifie gravity of
the liquid. R=Radius of particles. g=Gravity. N=Viscosity of liquid.

THE CARPENTER ANT AS A DESTROYER OF SOUND
WOOD*

By S. A. GRAHAM

The carpenter ant, Camponotus pennsylvanicus Degeer and its
variety ferrugineus Fab. have been universally referred to in ento-
mological literature as workers in decaying wood, but apparently never
have been regarded as pests of sound trees or timbers. Wheeler’ men-
tions the species repeatedly as a dweller in rotten and rotting wood but
never as attacking sound material. Marlatt? states that “it normally
constructs its galleries in logs and dead trees in the forests, but not in-
frequently, in the case of wooden houses, and especially those near
forested tracts, gains access through porch beams or the underpinning
of such houses and mines and weakens the supporting timbers and
other woodwork. As a rule, it affects only decaying portions of the
wood, but sometimes carries its channels into the sound wood.” Com-
stock® also refers to this species as working in rotten wood.

Until recently the observations of the author have tended to con-
firm the facts as set forth in literature, and so when reports were re-
ceived stating that ants were responsible for a large amount of dam-
age to standing white cedar in Minnesota, it was believed probable that
this ant injury was only secondary to heart rot and that the ants were
not primarily injurious. <A trip through the cedar districts of the state
showed, however, that this assumption was erroneous and that car-
penter ants were frequently found working in the solid heart wood of
living white cedars, causing extensive injury.

It seemed that this injury to living cedar has been regarded by the
cedar dealers as a necessary evil and except for culling heavily ant in-
jured poles, little thought has been given it. There has been no effort
to reduce the loss occasioned by this pest on the part of the cedar
men and perhaps for this reason the problem has never before come to
the attention of entomologists. It is nevertheless an important prob-
lem for the forest entomologist and will become more important with
the increasing scarcity of white cedar of pole size.

*Published with the approval of the Director as Paper No. 157 of the Journal
Series of the Minnesota Agricultural Experiment Station.

1 Wheeler—<Ants: Their Structure, Development and Behavior (1910).

2 Marlatt—House Ants: Kinds and Methods of Control U. S. D. A. Farmers
Bulletin 740 (1916).

3 Comstock, A Manual for the Study of Insects (1907).

32

ANTS IN CEDAR POLES 33

MetTHop or WorK

So far as observed, the carpenter ant never attacks a perfectly
sound tree, but always gains entrance through a wound or a decayed
spot. At first thought it would seem that this habit would result in a
scarcity of suitable nesting places and that the spread of the ants would
be limited by this factor to such an extent as to make their injury
negligible. This would probably be true if it were not for the fact
that in Minnesota less than five per cent of the white cedar of pole
size is sound, and many trees which appear sound on the stump have
injured or diseased areas near the ground. Thus almost every cedar
of pole size is a fit subject for ant attack.

hy u es ee a +P:

Fig. 5. Ant nest in cedar butt. X shows the position of a window.

After the colony has been established in a tree, the ants usually
work well above the rotten area into the sound heart wood, honey-
combing the tree with longitudinal galleries until there is often only
a thin shell of solid wood around the nest. Where the main nest 1s
located, they cut openings to the outside, frequently following out a
knot, through which the sawdust may be cast and through which the
inhabitants may pass to and from the nest. These openings, which
are known in the woods as “windows,” make it easy to locate the posi-
tion of the nest without cutting into a tree, since the nest never extends
far above the topmost window.

34 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

The height at which the nests are built varies greatly but they are
usually located within six feet of the ground. They may, however,
be occasionally built high in the trunk. As a rule, the ants gain en-
trance to a tree at a point near the base, sometimes even below the
ground level, starting either in the trunk or in a large root. Occa-
sionally entrance may be gained through a knot-hole in the trunk.
This latter is usually the case when the nest is located at a considerable
distance above the ground.

Fig. 6. Window opening to the outside.

EXTENT OF INFESTATION

The percentage of ant infested cedars varies with the conditions
under which the trees are growing. Trees growing in the swamps are
much less heavily infested than trees growing on higher ground.
Counts made on plots laid out under various conditions showed this
to hold true in every locality studied. A very good example of this
difference was shown in a series of plots located near Blackduck, Min-

ANTS IN CEDAR POLES 35

nesota. This was a series of one tenth acre plots running from high
land through a small swamp and up to the top of a ridge on the oppo-
site side. Plot number one was located on dry land just at
the edge of the swamp and showed an infestation of sixty per
cent. Plot number two was partly in the swamp and showed
an infestation of twenty-three per cent. Plot number three was
all in the swamp and showed an infestation of twenty-three per
cent. Plot number four was on the dry land sloping up from
the swamp with an infestation of seventy-two per cent. The next three

Fig. 7. Ant nest in cedar showing ants.

plots, numbers six, seven and eight were high on the ridge and showed
a sharp reduction in ant infestation to twenty-one, twenty-four and
thirty-eight per cent respectively. This was the only locality where
a sharp reduction of infestation on a ridge was observed. It was,
however, by far the highest ridge on which cedar was studied and so
no other plots were comparable to these. In addition to the high
elevation, the cedar on this ridge was mixed with other species of trees,
which may have had some influence on the extent of ant infestation.
The high infestation on the strip of dry land bordering the swamp,
which is shown so clearly in this series of plots, held true in every
locality. These observations in the field correspond with the observa-

36 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESoTA—1918

tions of men in the cedar yards who say that it is much less common
to find ants in the heavy, sour butts from the swamps than in the light
upland cedar.

In every locality where studies were made, the percentage of trees
infested averaged very nearly the same as that at Blackduck, which
would make the average infestation for the state run between fifteen
and twenty-five per cent in the swamps and from forty to seventy per
cent on the higher land. Altho the factors resulting in the heaviest
infestation occurring on the dry land just out of the swamp have not

Fig. 8. Three trees left “hanging’’ because they showed ant injury on the butt.

been determined, there are several possible theories. The first is
that since the ants are land animals, they prefer the dry ground to
the swamp, but this scarcely seems a satisfactory explanation since it
would be perfectly possible for the ants to make their way about in
the swamps without getting wet at practically any time of the year.
It is possible, however, that the wet condition of the ground would
tend to increase the moisture in the nests, making them less comfort-
able and increasing the danger of an epidemic of s6me fungous parasite
in the colony.

The percentage of trees with heart rot is greater on the dry ground
than inthe swamp. This factor may have considerable influence, since

ANTS IN CEDAR POLES 37

hig. 9. Tree which showed ant injury on the butt, butted off unnecessarily leaving
a stick too short for a pole. Left in the woods although
it would have made several good posts.

Fig. 10. Illustrating the custom of first cutting a pole to length and then butting off
for defect, a practice which results in much waste. Two feet from
the butt of this tree would have cleared it.

38 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

the heart rot would make it easier for the ants to gain entrance into
the trees. The difference in texture of the wood in swamp and high-
land cedar also may have its influence, since the wood of the swamp
cedars is much heavier and closer grained than that grown on the
higher land. All these factors probably have their influence in limit-
ing the extent of infestation in the swamps.

Since such a large proportion of ant infested cedar trees are also
hollowed more or less by heart rot, many poles which must be trimmed
for ant injury would necessarily have to be trimmed for rot even
though no ants were present. When it is remembered, however, that
the ants as a rule work above the rot into the solid wood, it is evident
that they increase considerably the length which must be cut from the
butt. From measurements made in the woods, it is estimated that in
the swamps there is an unavoidable loss of about three feet from the
butt of every ant infested cedar, and on the higher ground, where the
heart rot runs higher, the average loss runs nearly six feet. In either
case, allowing for heart rot it is safe to say that ants were responsible
for an average loss of at least two feet for each infested tree.

While there is an immense amount of unavoidable loss due to ant
injury, the loss occasioned by careless butting is still greater. This
is often due to the fact that many of the cedar makers do not know
how to locate accurately the ant nest, so as to insure cutting just above
it. Frequently a man will get only a 20-foot pole out of a tree which
should have made a 25- or 30-foot pole if properly cut. Sometimes a
man will hack into a pole every two feet until he finds it sound, thus
destroying any value which the butt may have had. It may occa-
sionally be necessary to follow up rot in this way, but where ants
are in a stick their nest is practically always above the rot and it is
only necessary to look for the topmost window to tell where to make
the cut with the least amount of loss. Therefore the first thing to do
in making a pole from an ant infested tree, is to look for the win-
dows and then measure up the pole and cut to the best advantage.
The usual method seems to be to make the pole and then begin butt-
ing off. There is also a great deal of good material in the butts which
could be used for posts, slats or other purposes where they can be
handled to advantage. Butting off the poles in the yard might help
save this loss in many cases.

It is the custom of most of the cedar men to cull very heavily for
ant injury. This custom has brought about a condition which results
in the absolute loss of large quantities of merchantable material as the
cedar makers will not spend their time on pieces which they think may

ANTS IN CEDAR POLES

Fig. 11. Poles showing both rot and ant injury.

Fig. 12.

Posts showing both rot and ant injury on the butts.

39

40 SEVENTEENTH Report STATE ENToMOLOoGIST oF MINNESOTA—1918

be culled. Asa result anything that looks like a cull is usually left in
the woods even though it may contain a considerable amount of good
material.

RECOMMENDATIONS

So far as protection from ant attack of cedar trees in the woods
is concerned, nothing can be recommended at the present time. It is
possible, however, to save an immense amount of merchantable mate-
rial by closer utilization of ant infested cedar, combined with intelli-
gent trimming of poles. Since it is possible to tell approximately
where a pole must be cut to clear it of serious ant injury by simply
looking for the topmost window, it seems unnecessary for the buy-
ers to cull so heavily for this defect as is the general rule at present.
The grading rules regarding this injury should be made more lenient,
so that a cedar maker can be reasonably certain to receive for a pole
what it is really worth. Dealers should accept ant poles at their full
value provided the injury is not such as to weaken the pole. Ii a pole
shows ant work on no more than 10 per cent of the butt surface, and
has no windows more than one foot above the butt, the pole should
not be considered weakened.

Until something of this sort is done it is certain that the cedar
makers will continue to leave in the woods many valuable poles and
much good post material.

SUMMARY

1. Large black ants commonly known as carpenter ants are doing con-
siderable damage to standing white cedar in Minnesota, at least twenty per
cent of the trees cut showing ant injury on the stump.

2. The colonies are started in a wound, knot hole, or decayed spot, usually
near the butt of the tree.

3. The ants hollow out a nest in the heart of the tree sometimes leaving
only a thin shell of wood around it, thus seriously weakening the tree at that
point.

4. From this nest the ants cut openings to the outside called windows
and to locate a nest it is only necessary to look for the windows.

5. Much unavoidable loss is occasioned by ant injury, but there is also an
immense amount of loss through careless cutting of poles.

6. Culling heavily for ant injury has meant leaving in the woods any-
thing that looks suspiciously like a cull.

7. The grading rules regarding ant injury should be made more lenient so
as to encourage more careful trimming of ant infested poles.

DROSOPHILA GIN BOTTER DS CERTIFIED) MibK
By Wo. A. RILEY

The finding of conspicuous extraneous matter in the household
milk supply is never very appetizing. When such material is found in
certified mill in bottles bearing the label, “This milk is certified by your
State Board of Health,” the customer is quite likely to feel and to
express an especial resentment. An instance of this nature which
recently came to my attention proved of much entomological interest
and led to a study which revealed that such cases are not so rare as
might be suspected from the fact that they do not seem to have been
recorded in our literature.

Early in September there was submitted to me a quart bottle of
milk which bore scattered along the sides some thirty small seed-like
specks about 214 mm. in length. Altho these were minute, they stood
out very conspicuously against the white background of the milk, as is
evident from the photograph reproduced herewith. In general appear-
ance they resemble grass—or “hay”’

seed and are often so interpreted
by workers in the dairies and distributing stations. More detailed ex-
amination revealed that the “seeds” were the puparia of a fly of the
genus Drosophila. Attempts to secure adults were made, but for
reasons which will appear later, these were unsuccessful.

The puparium does not correspond to any of the few that have
been accurately described. It is hoped that the accompanying figure
and the following notes may serve to definitely identify the species
when more is known concerning the life histories of the group.

The puparium is of a light straw color, 21% to 3 mm. in length by
0.8 mm. in width, strongly convex on the dorsal surface, but slightly
so on the ventral surface. The segmental limits and the cuticular ap-
pendages are well shown in the figure. The pharyngeal skeleton of the
larva is retained as a conspicuous black mass near the anterior end of
the puparium. The dorso-cephalic region is flattened: and from it
project the two digitate pupal spiracles. The basal portion of these
processes measures some 200 microns in length by 50 microns in diam-
eter and bears 11 filiform processes measuring up to 300 microns in
length. oe

{

1Published with the approval of the Director as Paper No. 145, of the Journal
Series of the Minnesota Agricultural Experiment Station.

4]

42 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

At the posterior end is a pair of spiracles
which represent the single ones of the larva
in Drosophila ampelophila and D. amoena,
whose life histories, thanks to the studies
of Professor Comstock in 1882, are the best
known. These spiracles are borne upon a
pair of clearly separated tubercles. In the
species under consideration, however, they
are carried on the distal end of a single
caudo-dorsal process, as is shown by the
illustration.

Naturally, both the customer and the
milk distributing company were anxious to
know the nature and the source of the in-
festation, while the health authorities were
interested in the possibilities of other gross,
tho less conspicuous, contamination. In
order to investigate conditions five of the
large distributing companies of the city
were visited. In each place I found that the
occurrence of these peculiar) “seeds sven
“bugs” was well known. All agreed that
they were most commonly found earlier in
the season tho two samples were obtained
at the time (September 30) and at another

lai are teytemaioes place they had been observed that day but

discarded. Two more infested bottles were
obtained the next day. Thus it would appear that the phenomenon is

not a rare one.

It developed, as was to be expected from the habits and length of
the life cycle of the flies, that the contamination was in bottles which
had been returned to the central stations infested. Lying about homes
and especially about restaurants and saloons, they had served to attract
the flies which oviposited in the souring milk. It was very significant
that one proprietor noticed the difficulty most frequently in Bulgarian
buttermilk bottles. That this was not the only source was evident
from the fact that the difficulty was observed in dairies that did not deal
in buttermilk, and that two of the samples sent were in cream bottles.

Judging from known life histories, the hatching larvae from the
first deposited eggs would be pupating within a week. The pupae are
sufficiently transparent to escape careless inspection and adhere so tight-

DROSOPHILA IN STERILIZED MILK

Fig. 14. Puparia of Drosophila attached to inside of milk bottle,

44 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

iy to the sides of the bottle that even thoro washing at the dairy fails to
remove them. When the bottles are filled, the insects stand out so
prominently that they are usually noted by the inspector and discarded,
but an occasional one gets to the wagons and is delivered to a customer.

There can be no doubt that in a properly managed dairy the pupae
are not only killed but are rendered thoroly innocuous. The bottles are
treated witha hot, almost boiling, caustic solution, washed in hot water
and come through the washing machine so hot that they cannot be han-
dled with comfort. In this condition there is nothing about them to at-
tract flies and the further process of bottling and sealing affords no op-
portunity or inducement for ovipositing. Even if eggs could be in-
troduced at this stage the milk would be disposed of before there was
any opportunity for the development of the later stages of the insect.

In view of the known habits of the pomace flies there is no reason
to suppose that the forms attracted to sour milk would necessarily be
of one species. Ina cream bottle secured subsequent to the inspection
trip there occurred along with the above described species a preponder-
ance of a considerably larger type of puparium. These measured 5 mm.
in length, nearly twice that of the other species, and were of a bright
brown color. The caudal spiracles were borne on paired tubercles.

In spite of an extensive search I failed to find in the entomological
literature any mention of Drosophila breeding in milk. The nearest
approach is an untraced reference to their occurring in rancid butter.
However, the phenomenon has not completely escaped attention. In the
Zeitschrift fur Fleisch und Milchhygiene, 1913, Vol. XXIII, p. 252-253,
Otto Fettick reports a similar case which came to his attention. The
specimens were in bottled milk which had been obtained from a large
distributing station. ‘Tho it is obvious from his description that he
was likewise dealing with puparia, he regarded them as larvae of
Drosophila or a related genus. He was unable to breed the adults and
concluded that since no motion was to be detected in the “larvae” they
were dead when received.

Fettick speculates as to the source of the contamination and dwells
especially upon the sanitary aspects of the question. He says:

“Fly larvae of this genus find suitable conditions for living in
shallow, easily warmed, foul water, containing organic matter, as well
as in moist, fermenting substances. They cannot live in pure spring
water suitable for drinking, or in tap water, into which, moreover, they
cannot get on account of their size (! R.). It is, therefore, highly
probable that the larvae found in milk reached it at the producing sta-
tion probably through washing and rinsing of the cans or milk

DROSOPHILA IN STERILIZED MILK 45

vessels with unclean and therefore insanitary water. It is,
however, not to be denied that the flies may have gotten into the dirty
bottles containing a residuum of milk before they were filled. For this
reason the milk in the bottle must be regarded as questionable from a
hygienic viewpoint.”

It was this view which first impressed itself upon me. A more
careful examination of conditions has convinced me that it is incorrect
and that the presence of the puparium is no index of the thoroness of
the sterilizing process which the bottles undergo before they are filled.
Indeed it would seem clear that, as in my experience, the failure of
Fettick to rear the flies was due to the fact that the pupae had been
killed by the washing process to which the bottles were subjected.

It must not be overlooked that the presence of such organisms is
but a readily visible illustration of the gross contamination which may
occur in milk bottles in homes and in business places. To one who has
seen conditions it is almost inconceivable that a housekeeper should
be willing to return bottles in the filthy condition in which they are
sometimes received by the dairies. It certainly affords argument for the
enforcement of ordinances requiring milk bottles to be washed when
emptied. il

My thanks are due to Mrs. Helen Sanborn Chapman for the faith-
ful manner in which she has executed the accompanying drawing of the
puparium. Iam also obligated to Mr. C. Kx. Linton, of the Minneapolis
City Health Department, who first brought this subject to my attention
and whose co-operation made it possible for me to study conditions in

Hly|

the local distributing stations.

CONTRIBUTION TO KNOWLEDGE OF THE TRIBES AND
HIGHER GROUPS OF THE FAMILY APHIDIDAE
(HOMOPTERA)

By O. W. OEsSTLUND

Aphids are of considerable importance from an economic stand-
point as all of them feed on the juices of plants. Their identification
and placing in a natural system of classification have become exceed-
ingly difficult of late on account of the great number of new genera
and species made known. The older groups, to which we had become
accustomed, are much overloaded and their demarcations proportionally
indistinct. The following paper is an attempt to bring this side of the
question up to date.

Several attempts have been made to arrange the family in
natural tribes and higher groups. The first serious attempt was made
by Koch, but as no characteristics were published, only the names with
included genera, it has remained practically unnoticed. Passerin1’s
classification has been followed by most writers up to very recent time.
Mordwilko’s arrangement is better and is gradually replacing that of
Passerini. Important additions have still later been made by Tull-
gren, Wilson, and others.

In the following, the attempt has been to give proportionate con-
sideration to the historical, morphological, and biological aspects as
necessary foundations toward a natural classification, which of neces-
sity is largely biological and historical, and not alone morphological.

Famity APHIDIDAE

Linnaeus, 1758, Syst. Nat. Ed. X. Sub Aphis (genus).

Latreille, 1807, Gen. Crust. Vol. 3. Sub Aphidii (family).

Leach, 1815, Encyeclop. Vol. 9. Sub Aphidae (family).

Burmeister, 1835, Handb. Entom. Vol. 2 Sub Aphidina (family).
Zetterstedt, 1840. Ins. Lap. Part 1. Sub Aphidiae (family).

Amyot et Serville, 1845. Hemipt. Sub Gradipedes (family).
Rondani, 1848. Nouy. Ann. Bologna Vol. 9 Sub Aphidinae (family).
Harris, 1852. Treatise Ed. 2. Sub Aphididae (family).

Early writers refer to members of the present family under such
common terms as pediculus, Blat-laus, puceron, plant-louse etc., which
varied with the language and the country. Linnaeus’(1758) named all
forms known to him according to the binomial system under the
generic term Aphis. Latreille (1807) united the genus Aphis with
Thrips and Aleyrodes under the family name Aphidii. Leach (1815)

46

TRIBES OF APHIDIDAE 47

corrected this to Aphidae, the term generally accepted by British
authors. Burmeister (1835) used the term Aphidina, which has been
extensively followed by authors on the continent. Other terms pro-
posed but not generally accepted are: Aphidiae, Zetterstedt (1840) ;
Gradipedes, Amyot et Serville (1843); Aphidinae, Rondani (1848).
Harris (1852) used the form Aphididae as now accepted by the best
writers.

Morphological characters. Much importance has been given to
the form of the head in the classification of aphids. Three types or
lines of modifications may be distinguished. First, the transverse
(generalized), in which the head is broader than long, the distance
between the antennae is wide and the frontal margin straight; this
form is characteristic of the Lachnina. Second, the subquadrate
(aphidian), in which the head is narrowed anteriorly and produced as
a pair of frontal tubercles on which the antennae are situated; the
frontal margin is concave or emarginated. Third, the reduced (pem-
phigian), correlated with the reduction of the antennae and the eyes
in the gall and underground forms of the Pemphiginae. The frontal
margin in this type is usually convex. The family is unique, as far
as known, in the presence of three types of insect eyes at the same
time in the alate forms: the larval eyes which persist through life as
the ocular tubercles with the compound eyes and the dorsal ocelli of
the alate forms. The antennae are typically composed of six segments.
The first two segments are short and broad, and usually devoid of
sense structures. The following segments are more slender and known
as the flagellum, and always provided with special sense structures as
sensilla and sensoria. The terminal segment is characterized by the
presence of a primary sensorium at the apex of the segment, and the
prolongation of the segment beyond the sensorium as a slender filament,
known as the spur, which carries a group of sensilla on the distal end,
very constant and characteristic of the family. The subterminal seg-
ment is also provided with one of the primary sensoria near its apex.

Various types of sensilla (sense hairs) are present on the anten-
nae which have considerable taxonomic value and may be distinguished
under the following heads: First, the long and slender hair-like sen-
silla of the flagellum as present in the Lachnina and related tribes.
Second, the short,and spine-like sensilla of the Aphidini. Third, the
glandular sensilla with enlarged apices of the Macrosiphini. Fourth,
the apical sensilla of the spur just referred to. The sensoria (sense
membranes) are of many kinds and very characteristic of the family.
The following types may be recognized: First, the reticulations or

48 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOoTA—1918

transverse folds of the flagellum. Second, the primary sensoria, usually
fringed with a row of hairs, one on the terminal segment close to the
base of the spur; and a second on the subterminal segment near the
apex. The primary sensoria are the first to appear and are usually
present in the larvae in the earliest stage as well as in the adult; they
are the most constant of all the sensoria. Third, the secondary sen-
soria, variable in number and position on the segments of the flagellum,
are characteristic of the adult but may be present in the larva as well.
The secondary sensoria are usually circular like the primary, but in
the Pemphiginae and forms with shortened antennae they become
crowded and may be transverse or annulated, extending around the
segment like a ring. Fourth, the marginal sensoria, a group of five or
six small sensoria close to the margin of the primary sensorium of the
terminal segment. The arrangement of the marginal sensoria shows
two distinct types: first, where they are scattered over some area, as
in the Lachnina and related tribes, which may be considered as the
primitive condition of the family; second, where they are grouped
close together in a row or in pyramidal form as in the Aphidina. Sen-
soria may also be present on other parts of the body, on the coxa, the
hind tibiae of oviparous females, on the wing-veins, and on the spur
of the antennae (Mordwilkoja). The rostrum is typically composed
of five segments, which is undoubtedly the primitive condition of the
family from which the more common four-segmented condition has
come by fusion of the two terminal segments. The five-jointed con-
dition is clearly seen in the Lachnini.. In some aphids the prothorax
is provided with lateral protuberances or tubercles, the significance
of which is obscure. Similar tubercles may also be found on the
segments of the abdomen, which indicates an original segmental
condition of these bodies. They are seen at their best in the Pterocom-
mini and certain Aphidini.

The long and slender legs of the Lachnina and the Macrosiphini
show undoubtedly the primitive condition of the family; the reduction
of the legs reaches its furthest in the gall and underground forms of the
Pemphiginae; atrophied and greatly modified tarsi are known only
for some of the more specialized genera of the Aphidini. The simple
venation of a Pemphigus is not to be considered as the primitive type,
but rather the complete venation of the Aphidinae from which the
secondary types are derived by reduction or loss of certain veins. Too
great value has been given to venation by most writers in establish-
ing the larger groups of the family. Modifications of the type form
(Lachnina) by reduction or loss of certain veins are found to have
taken place in several of the tribes, producing parallel and convergent

TRIBES OF APHIDIDAE 49

forms which are not necessarily closely related. The cornicles are the
most characteristic structures of the family. Nothing homologous
to them has been found in related families of the Homoptera, though
such organs probably occur. Several distinct types of cornicles may
be distinguished. First, the tuberculate type in which the short
cornicles are situated on cone-shaped and hairy tubercles of the body,
as present in the Lachnina. Second, the truncate type in which the
cornicles are usually not longer than broad and not found on hairy
tubercles; this type is characteristic of the Chaitophorina and the
Callipterina. Third, the cylindrical type as present in the Aphidina.
The Pemphiginae have the cornicles reduced to mere pores or are
wanting. Attention has often been called to the correlation of great-
ly developed cornicles with the corresponding great development of
the cauda. In the Lachnina the cauda is inconspicuous; the
Chaitophorina and Callipterina have the cauda triangular and pointed at
apex or sometimes enlarged (globate); the triangular and pointed
cauda is also characteristic of the Aphidina, where the cauda reaches
its greatest development in the Macrosiphini correlated with the great
development of the cornicles of this group. The Pemphiginae have
inconspicuous cauda correlated with the reduction or loss of the
cornicles.

Biological characters. Aphids are among the most defenseless of
insects, their soft bodies make them an easy and coveted prey to their
many enemies. Their strength lies in their great power of reproduction,
by which they more than hold their own against all their enemies.
The parthenogenetic mode of reproduction has become characteristic
of the family, probably more so than in any other group of insects.
Generation will follow generation in rapid succession through the sea-
son. Aphids are among the first insects to become active in spring
when they have the field all to themselves before their enemies make
their appearance. During the height of the season, when their enemies
have all but cleaned them out of their old haunts, the winged genera-
tions have appeared and they are carried by their wings and the wind
far and wide to establish new colonies in innumerable places. When
the cold of the fall has laid low their enemies, the aphids continue to
spread and multiply, and among the last insects of the season are the
sexes which then develop and deposit their winter eggs.

Protective resemblance is present to a marked degree in some
species, by which they escape their enemies. In the Pemphiginae
special protective structures are of common occurrence. The wax-like
secretions, so common in this group, envelop the individual and the

50 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

colony in a protective covering; some find their protection in folded
leaves, or in galls; many find their protection under ground on roots

of plants.
The number of generations for the season varies greatly; while

some produce only a few, in others the generations follow in rapid
succession. The successive generations may show considerable differ-
ences in structure, so much so that they would easily be considered as
different insects. The following five types of generations may be con-
sidered as typical of the family. First, the fundatrix (foundress or
stem-mother), the individual that comes from the egg and gives rise
to the following generation; the fundatrix is always apterous. Sec-
ond, the spuriae (wingless viviparous females or spuriae apterae) ; the
second may have a number of successive generations all alike. Third,
the migrants (winged viviparous females or spuriae alatae vel mi-
grantes), which acquire wings and serve for the distribution of the
colony; this generation may be followed by one or more generations of
spuriae that are counterparts of the second type. Fourth, the sex-
uparae, the last generation of spuriae (apterous or alate) with which
the parthenogenetic mode of reproduction comes to an end for the
season and which produces the following type. Fifth, the sexuales or
true sex forms, the males and females, which, after copulation, pro-
duce the true ova which remain over winter for the next season.
While the females are always apterous, the males may be either alate
or apterous. The succession of generations in the order given may be
considered as typical of the family, to which many exceptions are
found in the different groups. Thus the second generation may be com-
posed of migrants, followed by spuriae, or there may be several gen-
erations of migrants following each other or at various times during
the season; a generation of spuriae may produce in part spuriae and
in part migrants. Aphids appear to be greatly influenced by external
changes and conditions; under favorable conditions they will continue
to produce generation upon generation of spuriae, but with changed
conditions of temperature and nature of the food only migrants are
produced. The Callipterina constitute a remarkable exception in that
all the parthenogenetic generations acquire wings before reproducing.

Aphids feed upon juices of plants. The part of the plant to
which they have become adapted is various but may be considered
under the following heads. First, the bark feeders (corticola), found
on woody parts of trees and other woody plants. Second, the root
feeders (radicola), feeding underground at base of the trunk or on
roots. This type may be considered as an early adaptation of the
first type and is common in the Pemphiginae. Third, the leaf feeders

TRIBES OF APHIDIDAE 51

(folicola) feeding on the tender twigs and leaves of trees and woody
plants. Fourth, those feeding on annual plants (herbicola), which un-
doubtedly represent the latest type of development in the direction
of food habitat.

KEY TO THE SUBFAMILIES OF THE APHIDIDAE

1. Typical Aphididae in which the aphidian characters are usually expressed by
increase or additions, as seen in the development of the spur and sensoria of the
antennae; and in the great development of the cornicles and cauda. The group is
typically aerial in habitat. .. . Subfamily APHIDINAE

—Specialized Aphididae in which the typical aphidian characters are specialized
in the line of reduction or loss, as seen in the number of segments to the antennae,
in the spur, sensilla and sensoria; in the reduction or loss of the cornicles and cauda ;
reduction in venation is also carried further in this group than in the preceding.
The group is typically subterraneous or protected in habitat, as found in folds of
leaves, in crevices of bark, or in galls. Positive pemphigian characters are seen in
the great development of dermal glands. . . . Subfamily PEMPHIGINAE

SuBFAMILY APHIDINAE

Retzius, 1783, DeGeer’s Genera. Sub “Fam. I. Abdomen corniculatum.”
Latreille, 1807, Gen. Crust. Vol. 38. Sub Bicorniculatum et bituberculatum.
Leach, 1818, Trans, Hort. Soe. Vol. 2 Sub Eriosoma (genus).

Burmeister, 1835, Handb. Entom. Vol. 2. Sub Lachnus (genus).

Koch, 1854, Die Pflanzenl. Heft 1. Sub Dikyphonen et Monokyphonen.
Passerini, 1863 Aphid. Ital. Sub Aphidinae et Lachninae (subfamilies).
Buckton, 1876, Monogr. Vol. 1. Sub Aphidinae (subfamily).

The subfamily Aphidinae was foreshadowed by Retzius (1783)
and Latreille (1807) in their grouping of the species of the genus
Aphis. Leach (1818) first indicated the Pemphiginae by the genus
Eriosoma, restricting the genus Aphis as representative of the present
subfamily. Burmeister further divided the genus by erecting the genus
Lachnus which became the foundation of Passerini’s subfamily
Lachninae. Koch (1854) indicated the subfamily names Dikyphonen
and Monokyphonen, both of which are nomena nuda. Buckton (1876)
united Lachninae with Aphidinae which is now generally taken as the
natural limits of the subfamily.

Morphological characters. Vhe positive characters of the sub-
family are seen in the gradual increase or direct development of the
antennae and the spur, the sensilla and sensoria, and the cornicles
and cauda. The Pemphiginae, on the other hand, show a non-develop-
ment or reduction and loss of the same characters.

Biological characters. Three distinct stages or steps of food
habitat may be distinguished in the present subfamily. First, those
feeding on woody part of trees, which is undoubtedly the primitive
food-habitat of the family. This is characteristic of the Lachnina and
the more generalized Chaitophorina. Second, those feeding on tender

52 SEVENTEENTH Report STaTE ENTOMOLOGIST OF MINNESOTA—1918

twigs and leaves of trees and woody plants; characteristic of the
Chaitophorina and Callipterina. Third, those feeding on annual plants
as characteristic of most of the Aphidina. In form of the partheno-
genetic generations two distinct types may be distinguished in the
subfamily. First, where all the parthenogenetic generations acquire
wings before reproducing, as in the Callipterina. Second, where these
same generations are either winged or wingless which is the condition
of the other groups of the subfamily.

KEY TO THE GROUPS OF TRIBES OF THE APHIDINAPD
1. Cornicles short and rim-like situated on cone-shaped hairy tubercles; anten-
nae usually less than one-half the length of the body and provided with long hairs;
spur short. Iound on the bark of woody plants. . . . I. LACHNINA
—Cornicles not situated on hairy tubercles, cylindrical and conspicuous, some-
times much reduced or variously modified, rarely hairy (Trichosiphini). Usually
found on annual plants or the growing parts and leaves of woody plants.

2.

2. Cornicles short and of the truncate type; if longer than broad then variously
enlarged, rarely cylindrical. .. . 3.
—Cornicles long and cylindrical; sometimes short but then not of the truncate
UVP. Wh Xs 4.

3. Antennae and legs with long slender hairs; cauda broad or pointed, rarely
enlarged at apex; the parthenogenetic summer generations in part wingless (Spuriae)
and in part winged (Migrants); colonies usually strongly gregarious; found on the
leaves of woody plants, sometimes on bark. . . . Il. CHAITOPHORINA

—Antennae and legs smooth or with short hairs; cauda usually globate at apex
and anal plate more or less emarginate; the parthenogenetic summer generations all
acquire wings (Migrants) before reproducing; colonies sporadic, i. e. more or less
seattered; found on leaves of woody plants, rarely on annuals.

» lil, CALLIPTERINA

4. The cylindrical cornicles provided with numerous long, spreading hairs; Asiati¢e
HORM S sary wel we IV. TRICHOSIPHINA
—Cornicles not hairy, or at most with a few hairs; found mostly on annual
plants, sometimes on leaves of woody plants. . . . V. APHIDINA

I. Group LACHNINA

Retzius, 1788, DeGeer’s Genera. Sub Abdomen tuberculatum.
Latreille, 1807, Gen. Crust. Vol. 38. Sub Abdomen bituberculatum.
Burmeister, 18385, Handb. Entom. Vol. 2. Sub Lachnus (genus).
Koch, 1854, Die Pflanzenl. Heft 1. Sub Lachniden (tribe).
Passerini, 1863, Aphid. Ital. Sub Lachninae (subfamily).
Buckton, 1876, Monogr. Vol. 1. Sub Aphidinae (subfamily).
Thomas, 1879, Report 8. Sub Lachnini (tribe).

Mordwilko, 1908, Acad. Imper. Vol. 18. Sub Lachnina (group).

The group Lachnina has been long in coming to its present limits
and position in the family. The group was foreshadowed by Retzius
(1783) and Latreille (1807). Burmeister (1835) erected the genus
Lachnus, the foundation of the present group. Koch (1854) united
a second genus with Lachnus under the tribal name Lachniden which is
a nomen nudum. Passerini (1863) first gave the group the subfamily

name Lachninae. Buckton placed it as a tribe under the Aphidinae.

TRIBES OF APHIDIDAE 53

Thomas (1879) named the tribe Lachnini. Mordwilko (1895-1908)
first clearly indicated the limits of the group under the term Lachninae
which he later changed to the better term Lachnina.

Morphological characters. Head transverse, with frontal margin
broad and straight. Antennae have six segments, rarely only five;
usually less than half the length of the body; spur of the terminal seg-
ment short and undeveloped; segments of the flagellum provided with
numerous long, spreading hairs; secondary sensoria mostly large and
circular, but variable in number and position; marginal sensoria more
or less scattered and not forming a compact group. The rostrum is
usually long, sometimes as long as or longer than the body. In the
Lachnini the rostrum is distinctly 5-jointed. Legs long and slender,
the hind pair especially so; they are usually provided with long and
spreading hairs like those on the body. Wings are large and the
venation is typical of the family; stigma long and slender, rarely short
and broad; stigmal vein (Rs) originating from the distal end of the
stigma and runs as a straight vein to the margin, or, when originating
some distance from the apex of the stigma, it is more or less curved;
the media is a very faint vein in the Lachnini, but more distinct in the
Pterochlorini. The cornicles are short, often mere pores, situated on
conspicuous cone-shaped, hairy tubercles which are seldom much re-
duced or wanting. The cauda is short and broad and not conspicu-
ous.

Biological characters. It becomes apparent from extended mor-
phological and biological studies on the family that the Lachnina rep-
resent the most generalized and primitive forms of the Aphididae that
are in existence at the present time, and that they give the key to the
phylogenetic understanding of the family. This is indicated by their
size, form of the antennae, the structure of the sensilla and sensoria,
the long rostrum with the free distal segment, the venation, and the
form of the cornicles and cauda. But more so does the habitat of
the group, as bark feeders on conifera and deciduous trees, indicate
that they are a remnant of a group that in the past predominated and
gave characters to the family. Paleontology also, as far as known,
points to similar conclusions.

KEY TO THE TRIBES OF THE LACHNINA
1. Stigma long and stigmal vein takes its origin from the distal end of the
truncate stigma and runs as a short, straight vein to the margin; media appears as an
indistinct vein. They are found.feeding on the bark of coniferous trees. 6
1. Tribe LACHNINI
—Stigma long or sometimes short, with the stigmal vein arising some distance
back from the apex of the stigma and curved more or less before reaching the margin;

media slender but distinct. They are found feeding on the bark of deciduous trees
and woody plants. ... 2. Tribe PTEROCHLORINI

54 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

I. Trine LACHNINI

Kaltenbach, 1843. Monogr. Sub **) Radialzelle ete.

Koch, 1855. Die Pflanzenl. Heft 7. Sub Lachnus (genus s. str.)
Mordwilko, 1895 Zool. Anzeig. Vol 18. Sub “Baumliéiuse”.
Cholodkovsky, 1898. Beitr. Monogr. Sub ‘“‘Coniferen—lduse.”

Hartig (1841), in his definition of the genus based on venation,
undoubtedly had in mind a true Lachnus as the type but included also
the heterogeneous forms of Burmeister to which he adds further.
Kaltenbach (1843) recognized this polygeneric condition and remarks
that the genus can not long continue as such; he separates the in-
cluded forms in two sections, the second of which in main corresponds
to the present tribe. Koch (1855) restricts the genus Lachnus to in-
clude the conifer forms. Mordwilko (1895) treats the genus Lachnus
(Burm.) Koch in a tribal sense, in which he is followed by Cholod-
kovsky (1898).

Morphological characters. The distinguishing characters of the
present tribe are found in the venation of the wings. The stigma is
long and narrow, and the stigmal vein takes its origin near the distal
end of the more or less truncated stigma and runs as a short and
straight vein to the margin of the wing. The media appears as a faint
and indistinct vein; it is normally two-branched but sometimes with
only one branch or simple. The Lachnini are further distinguished
by their five-jointed rostrum.

Biological characters. The Lachnini are mostly large; in color
brown or black, those feeding on the needles alone show the green
so common and characteristic of the family. They are all but confined
to conifers, feeding on the trunk and limbs, or on the tender twigs
and needles. They have a wide distribution in the temperate zone, but
have the appearance of a vanishing group with the gradual restriction

ra)
and disappearance of the Conifera.

2. TRinE PTEROCHLORINI

tondani, 1848. Ann. Sci. Nat. Bologna, Vol. 9. Sub Pterochlorus (genus).
Koch, 1855. Die Pflanzenl. Heft 7. Sub Dryobius (genus).

The Pterochlorini are here recognized for the first time as a dis-
tinct tribe; the forms included have hitherto been considered with the
Lachnini. Rondani (1848) first established the genus Pterochlorus
with Aphis roboris L. as type. Koch (1855), not aware of Rondani’s
paper, proposed the generic term Dryobius for the same species as
type, to which he added a second also from the oak. The tribe is

TriBes OF APHIDIDAE 55

readily separated from the preceding by structural as well as biological
characters.

Morphological characters. Antennae six-jointed. Rostrum some-
what shorter and stouter than in Lachnini; apparently four-jointed ;
some forms of the tribe are provided with an exceptionally long
rostrum, much longer than the body, which is evidently an adaptation
and of secondary value. Wings usually long with distinct venation ;
the stigma elongated and coming to a point at the apex, rarely approach-
ing the truncate ; forms with short wings have a short and broad stigma ;
stigmal vein takes its origin some distance back of the apex of the
stigma and runs as a straight vein to the margin of the wing except
for a short curve close to its origin. Forms with short stigma have
a strongly curved stigmal vein. The media is twice branched and
appears as a stronger vein than in the Lachnini.

Biological characters. The Pterochlorini are among the largest
of our aphids, with exceptionally long hind legs. The group is found
as bark feeders on the trunk and limbs of deciduous trees and other
woody plants; more rarely underground near the base of the trunk
or on roots. They are usually found in more exposed places than the
shade loving Lachnini; they are, therefore, more highly colored, the
wings often with dusky bands along the veins and with dusky spots.
In their essential characters they show a close relationship with the
Lachnini.

II. Group CHAITOPHORINA

Koch, 1854-1857. Die Pflanzenl. Sub Aphiden, Phyllaphiden, et Vacuniden.

Passerini, 1863. Aphid. Ital. Sub Aphidinae, Lachninae et Chermisinae.

Buckton, 1876-83. Monogr. Sub Aphidinae et Pemphiginae.

Thomas, 1879. Report 8. Sub Aphidini Lachnini et Pemphiginae.

Oestlund, 1887. Bull. 4. Sub Callipterini.

DelGuercio, 1900. Nuoy. Relaz. Vol. 2. Sub Aphidinae et Myzoxylinae.

Mordwilko, 1907-8. Acad. Imper. Vol. 18. Sub Aphidina, Callipterina et Pem-
phiginae.

Wilson, 1910. Canad. Entom. Vol. 42. Sub Callipterinae.

The genera of the present group have for a long time been dis-
tributed under the various groups or tribes of the Aphidina, Lachnina,
Callipterina and Pemphiginae and only recently have they been united
under a common name. Koch (1854) first established the genus
Chaitophorus under his Aphiden, other related genera were placed
by Koch in the Phyllaphiden and Vacuniden. Passerini (1863) placed
most of the genera in the Aphidinae, except that Sipha was placed in
the Lachninae, and Vacuna with the Chermesinae. Buckton (1876-
1883) distributed the genera treated in part under Aphidinae and in

56 SEVENTEENTH Reporr STATE EntTomoLocist oF M1INnNEsSoTA—1918

part under the Pemphiginae. Thomas (1879) has the genera dis-
tributed under Aphidini, Lachnini, and Pemphiginnae. O¢cstlund
(1887) united Chaitophorus and related genera with Callipterus and
related genera under the tribal name Callipterini, based mainly on
similar type of cornicles and cauda. |Mordwilko distributes the
genera under the subfamilies Aphidinae and Pemphiginae. Wilson
(1910) first united the genera under the three tribes Pterocommini,
Chaitophorini, and Vacunini in the Callipterinae. The three tribes of
Wilson are considered under the group Chaitophorina.

Morphological characters. Head transverse; frontal margin
straight or but slightly concave. Antennae usually shorter than the
body and not on frontal tubercles, or on very indistinct ones; spur of
terminal segment elongated and distinct, usually longer than the prox-
imal part; sensilla long and slender as in the Lachnina, but not as
numerous; marginal sensoria sometimes scattered but more often
grouped close together near the margin of the primary sensorium.
Rostrum very short in the leaf inhabiting forms, longer in the bark
ieeders. Wings with typical venation, or reduced in the Vacunini;
veins often found in dusky bands. Cornicles of the truncate type;
usually not longer than broad, or if longer more or less enlarged in the
middle. Cauda short and broad as in Lachnina, or elongated and
pointed; in some the apex is distinctly globate as in the Callipterina.
Anal plate with distal margin entire, rarely slightly emarginated. Body
usually elongate and somewhat depressed, provided with long hairs. Dis-
tinctive characters of the tribe that separate them from the Lachnina
are the short rostrum, the grouping of the marginal sensoria, and the
cornicles and cauda.

Biological characters. Not a few of the present group are found
as bark feeders on the trunk and limbs of deciduous trees; these are
usually of a large size, approaching in this respect the Lachnina. The
larger number of the group are found on tender twigs and on the leaves
of trees, rarely on annual plants. The Vacunini are anomalous forms,
which most writers have placed with the Pemphiginae on account of
their one branched media and reduced cornicles, but a more critical
examination of the tribe shows that they are better associated with the
Chaitophorina. Following Hartig, too great weight has been given to
venation by authors, and many unnatural relations have been estab-
lished as a result. Venation is a character of primary importance in
the family, but when taken unsupported by other characters has no
more value than those of the antennae, cornicles, cauda, ete.

TRIBES OF APHIDIDAE 57

KEY TO THE TRIBES OF THE CHAITOPHORINA

1. Cornicles usually longer than broad and enlarged in the middle; size large.

Found feeding on woody parts of trees. . . . 3. Tribe PTEROCOMMINI
—Cornicles short and truneate; size smaller. Found feeding on leaves of
TLEGS ES a" 2.
2. Antennae of six segments. .. . 4. Tribe CHAITOPHORINI
—Antennae of five segments. . . . 5. Tribe VACUNINI

3. Trre PTEROCOMMINI

Koch, 1857. Die Pflanzenl. Heft 8. Sub Cladobius (Phyllaphiden).

Passerini, 1860. Gli Afidi. Sub Aphioides (pro Cladobius).

Buckton, 1879. Monogr. Vol. 2. Sub Melanoxanthus et Pterocomma.

Mordwilko, 1894. Uniy. Warsch. Sub Symdobits.

Pergande, 1900. Proce. Wash. Acad. Sci. Vol. 2. Sub Cladobius (Koch) Perg.
Kirkaldy, 1905. Canad. Entom. Vol. 37. Sub Aristaphis (pro Cladobius).
Schoutenden, 1906. Mem. Belg. Vol. 12. Sub Melanoxantherium (pro Melanoxanthus).
Wilson, 1912. Canad. Entom. Vol. 42. Sub Pterocommini (tribe).

The Pterocommini have only lately been recognized as a distinct
tribe. Koch (1857) erected the genus Cladobius, the first generic dis-
tinction of the tribe. Passerini (1860) changed this to Aphioides as
Cladobius was preoccupied. Buckton (1879) proposed two new
genera, Melanoxanthus and Pterocomma, the second of which is now
known to be the same as Koch’s Cladobius and replaces this as Pas-
serini’s Aphioides also proves to be preoccupied. Mordwilko (1894)
erected the genus Symdobius which is closely related to the present
tribe. Pergande (1900) considers the American forms under Koch’s
term Cladobius in a somewhat enlarged sense. Kirkaldy (1905) makes
a third attempt to replace the preoccupied term Cladobius under the
name Aristaphis. Schouteden (1906) proposed Melanoxantherium
to replace Melanoxanthus which also proves to be preoccupied. Wil-
son (1910) first recognized the tribe Pterocommini.

Morphological characters. Rostrum moderately long, but shorter
than in the Lachnina. Antennae variable in length, usually shorter
than the body, rarely as long as the body; terminal segment short and
with a short but distinct spur; marginal sensoria sometimes scattered
but more often grouped close together. Wings large and venation typi-
cal, veins sometimes with dusky bands. Abdomen usually with dis-
unct lateral tubercles, a character sharply marked in the present tribe
and again in the Aphidini; the significance of these organs is not
known. Cornicles longer than broad and widest in the middle; rarely
cylindrical, reduced or wanting. Cauda short and broad.

Biological characters. In size the present tribe includes all the
iarger forms of the group; all are bark feeders on woody parts of
trees and in exceptional cases on roots. Body with long hairs and of

58 SEVENTEENTH Report STATE ENtTomoLocist oF MINNESoTA—1918

dusky colors. The close relationship of the tribe to the Lachnina
is plainly seen in their size, colors, and especially in their habitat as bark

feeders.

4. Tre CHAITOPHORINI

Koch, 1854. Die Pflanzenl. Heft 1. Sub Chaitophorus (genus).
Oestlund, 1887. Bull. 4. Sub Callipterini (tribe).

Mordwilko, 1908. Ann. Aed. Imp. Vol. 18. Sub Chaitophorini (tribe).
Wilson, 1910. Canad. Entom. Vol. 42. Sub Chaitophorini (tribe).

Koch (1854) recognized the essential characters of the tribe un-
der the generic term Chaitophorus, which was placed under his Aphi-
den. Oestlund (1887) united Chaitophorus and related genera with
Callipterus under the tribal name Callipterini. Mordwilko (1908)
recognized the tribe Chaitophorini but included the Pterocommini.
Wilson (1910) first recognized the tribe with its present limits.

Morphological characters. Frontal margin straight or nearly so
with no antennal tubercles; antennae shorter than the body, provided
with long spreading hairs like those on the body and appendages ;
rostrum short and stout, rarely extending beyond the third pair of
legs. | Cornicles short and broad, usually broadest at base, truncate at
apex or with a narrow margin. Cauda short, rounded or triangular
and rarely with the apex globate.

Biological characters. ‘he Chaitophorini are nearly all found on
leaves or tender twigs of deciduous trees, rarely on annual plants. They
do not show the robust form of the Pterocommini and Lachnina, but
are smaller with moderately short legs. In color they are usually
found with more or less green in harmony with their habitat on the
leaves of trees. The tribe shows close affinity to the Lachnina in their
hairy body and appendages; as well as in their habitat on trees.

5. Tre VACUNINI

Heyden, 1857. Mus. Senk. Vol. 2 Sub Vacuna (genus).

IKkoch, 1854. Die Pflanzenl. Heft 1. Sub Vacuniden (tribe).
Passerini, 1868. Aphid. Ital. Sub Chermesinae (subfamily).
Thomas, 1879. Report 8. Sub Vacunini (section).

DelGuercio, 1900. Nuoy. Relaz. Vol. 2. Sub Vaeunides (tribe).
Mordwilko, 1908. Acad. Imper. Vol. 18. Sub Vacunina (group).
Wilson, 1910. Can. Entom. Vol. 42. Sub Vacunini (tribe).

Heyden (1837) first recognized the genus Vacuna that fore-
shadows the present tribe. Koch (1854) placed Vacuna in his tribe
Vacuniden which is a nomen nudum. Passerini (1863) placed Vacuna
with Chermes in the subfamily Chermesinae. Thomas (1879) con-

Trises oF APHIDIDAE 59

sidered it as a section under the subfamily Pemphiginae. DelGuercio
(1900) characterized the tribe Vacunides under the subfamily Pem-
phiginae. Mordwilko (1908) considers it as the group Vacunina
under Pemphiginae. Wilson places it as the tribe Vacunini in the
subfamily Callipterinae. In the present paper it is considered as a
tribe in the group Chaitophorina.

Morphological characters. Antennae short, not much longer than
the head and thorax combined; five segmented but often a six seg-
mented condition is found in one or both the antennae of certain in-
dividuals; spur of the terminal segment very short, Rostrum short
and stout. Wings held flat in repose; media one-branched; hind
wings with only one oblique vein. Cornicles very short, extending
but slightly above the surface of the body. Cauda short and rounded,
or when longer then enlarged at apex or globate.

Biological characters. Small size. Found on smaller twigs and
sometimes on the leaves of woody plants as birch, alder and dogwood.
The tribe is remarkable in the extent of reduction that has taken place
in the antennae, cornicles and venation, in convergence with the sub-
family Pemphiginae.

tik Grover CALEIP PE RINA

Koch, 1854. Die Pflanzenl. Heft 1. Sub Drepanosophiden et Callipteriden.
Passerini, 1863. Aphid. Ital. Sub Aphidinae et Lachninae (subfamilies).
Thomas, 1879. Report 8. Sub Siphonophorini et Aphidini (subfamilies).
Oestlund, 1887. Bull. 4. Sub Callipterini (tribe).

Mordwilko, 1908. Ann. Acd. Sei. Vol. 13. Sub Callipterina (group).
Wilson, 1910. Can. Entom. Vol. 42. Sub Callipterini (tribe).

Koch (1854) recognized the two tribes Drepanosiphiden and Cal-
lipteriden, both of which are nomena nuda. Passerini (1863) dis-
tributes the genera under the subfamilies Aphidinae and Lachninae,
and Thomas (1879) under the tribal names Siphonophorini and
Aphidini. Oecestlund (1887) united the present group with the Chaito-
phorina under the tribal name Callipterini. Mordwilko (1908) first
recognized the group under the term Callipterina. Wilson (1910)
considers the same under the tribal name Callipterini.

Morphological characters. Antennae variable in length, spur like-
wise ; never hairy as in the preceding group; secondary sensoria usually
confined to the basal half of the third segment, arranged in a row;
marginal sensoria often scattered or found in a row close to the pri-
mary. Rostrum short or at most moderately long. Venation typical;
the stigmal vein often reduced, at least the basal part. Cornicles short
and truncate like those of the Chaitophorina, rarely short cylindrical or

60 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

enlarged near the base. Cauda usually distinctly globate, sometimes
straight and rounded at apex. Anal plate usually distinctly emargin-
ated, often bifurcate.

Biological characters. In size the Callipterina vary from rather
large to very small. They are found feeding on the leaves of woody
plants and trees, rarely on annuals. The group has much in com-
mon with the Chaitophorina both in structure and habitat, but is
sharply distinguished in that, with few exceptions, all the partheno-
genetic generations acquire wings before reproducing. They are fur-
ther distinguished by not forming large colonies but live scattered and
show greater activity than usual in the family. Not a few of the
species have the ability to leap, reminding one strongly of the Psyl-
lidae.

KEY TO THE TRIBES OF THE CALLIPTERINA
1. Size large and Microsiphum-like; cornicles short, sometimes enlarged at base;
eauda long and unusually straight with the apex rounded.

6. Tribe CALAPHIDINI
—Size moderately large to small; cauda glokate. . . . 2

ie
i)

2. Cornicles rarely longer than broad, truncate at tip, rarely wanting; spur of
the terminal segment usually not much longer than he basal part. sometimes

Shorter... . 7. Tribe CALLIPTERINI
—Cornicles longer than broad and enlarged; antennae and spur exceedingly
Lonnie > eo), 8. Tribe DREPANOSIPHINI

6, “ripe CALAPHIDINI

Walsh, 1862. Proc. Entom. Soe. Vol. 1. Sub Calaphis (genus).

The tribe is here recognized for the first time. Walsh (1862)
first foreshadowed it by the genus Calaphis which gives the name to
the tribe. It is a curious fact that we may recognize a race of large
torms and one of small forms running through the subfamily
Aphidinae. Tribes of the large race-form are some of the Ptero-
chlorini, the Pterocommini, Calaphidini, and Macrosiphini.

Morphological characters. Antennae usually much longer than
the body and situated on distinct frontal tubercles; front concave as
in Macrosiphum. Rostrum short. Cornicles short, cylindrical, and
sometimes enlarged at base. Cauda straight with a rounded apex.
Anal plate entire or slightly emarginated, never deeply bilobed.

Biological characters. These large and Microsiphum-like forms
are found on the leaves and tender twigs of alder and birch. The
tribe has characters that ally it with the Lachnina as well as the
Microsiphini, while its more fundamental characters place it natu-
rally in the Callipterina. Some of the species at least are further
characterized by wax glands on the body, legs and antennae, which

Trripes oF APHIDIDAE 61

secrete an abundant white wax substance in tufts or bands that give
them a very peculiar appearance, and may serve as a protection against
some of their enemies.

7, tren CALEIPTERINT

Kkoch, 1855. Die Pflanzenl. Heft 7. Sub Callipterus (genus).
Mordwilko, 1908. Ann. Acad. Sci. Vol. 183. Sub Callipterini (tribe).
Wilson, 1910. Can. Entom. Vol. 42. Sub Callipterini (tribe).

Koch (1855) erected the first genus of the tribe. Mordwilko
(1908) included most of the genera under the tribal name Callipterini.
Wilson (1910) uses the term Callipterini in the sense of our Callip-
terina including the three tribes here distinguished.

Morphological characters. Front not deeply emarginate nor with
frontal tubercles ; antennae usually as long as or longer than the body ;
spur shorter than, equal to, or much longer than the proximal part of
the segment. Venation normal, but stigmal vein often indistinct, at least
the basal portion. Cornicles short and truncate, sometimes much re-
duced or wanting. Anal plate usually deeply emarginate, sometimes
bilobed. Larval forms with distinct glandular hairs on the body.

Biological characters. Vhe Callipterini have long been favorites
with students of the family. Most delicate in structure and extremely
variable in color and organization they have also been a favorable hunt-
ing ground for the genus makers. They are found almost exclusively
on leaves of deciduous trees.

SRE DRE PAIN © Sip EEENi

Koch, 1854, Die Pilanzenl. Heft 1. Sub Drepanosiphiden (tribe).
Oestlund, 1887, Bull, 4. Sub Callipterini (tribe).

Koch (1854) recognized the tribe under the name Drepanosi-
phiden which is a nomen nudum. Oecstlund (1887) considers it under
the tribe Callipterini.

Morphological characters. Front more or less concave as in the
Macrosiphini but the antennal tubercles are not large. Antennae as a
rule much longer than the body; the extreme length seems to have been
reached in this tribe of the family; spur of the terminal segment ex-
ceedingly elongated in comparison with the basal part which is short
and not elongated as is usual in the Callipterini. Cornicles vary from
short to long, and usually variously enlarged, departing from the cylin-
drical form. Cauda short and conical or even globate. Anal plate
more or less emarginate.

62 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Biological characters. The type form of the tribe appears very
much like a Macrosiphum, with which it has generally been associated
by authors. The more fundamental characters prove it closely allied
to the Callipterina. They are sporadic and all the generations acquire
wings before reproducing, a condition known only for the Callipterina.
They are found on the leaves of various deciduous trees.

IV. Group TRICHOSIPHINA

Westwood, 1890. Entom. Soe. Lond. Sub Siphonophora (genus).
Schouteden, 1905. Spol. Zeyl. Vol. 2. Sub Greenidea (genus).
Pergande, 1906. Entom. News, Vol. 17. Sub Trichosiphum (genus).
Okajima, 1908. Bull. Tokyo, Vol. 8 Sub Trichosiphum (genus).
Wilson, 1910. Ann. Ent. Soe. Am. Vol. 3. Sub Trichosiphini (tribe).

Westwood (1890) described the first representative of the tribe
which he placed in the genus Siphonophora. Schouteden (1905) pro-
posed the genus for Westwood’s species. Pergande (1906) adds a
second genus, Trichosiphum. Okajima (1908) describes additional
species and suggests that the group perhaps represents a new subfamily.
Wilson (1910) places the group as a tribe under the Aphidina.

Morphological characters. Antennae variable in length and com
posed of five or six segments; spur variable but longer than the prox1-
mal part; antennae beset with long, spreading hairs as in Lachnina.
Cornicles usually of the cylindrical type and very long and provided
with long hairs like those on the body, antennae, and legs. Cauda
short and triangular like the Aphidini.

Biological characters. This interesting tribe seems to be confined
to Asiatic countries, India and Japan, and is imperfectly known. All
the forms so far made known are feeders on leaves of woody plants.
The venation and long cylindrical cornicles would seem to place them
close to the Microsiphini, but their exceedingly hairy cornicles and body
indicate a still closer relationship to Lachnina. As the tribe does not
come within our area it may be passed with only an indication of its
position in the family. One tribe is known, the TrictostPHINI.

V. Group APHIDINA

Linnaeus, 1758, Syst. Nat. Ed. X. Sub Aphis (genus).
Burmeister, 1885, Handb. Entom. Vol. 2. Sub Aphidina (family).
Koch, 1854, Die Pflanzenl. Heft 1. Sub Aphiden (tribe).
Passerini, 1863, Aphid. Ital. Sub Aphidinae (subfamily).
Thomas, 1878, Bull. Ill. State Lab. No. 2. Sub Aphidini (tribe).
Mordwilko, 1908, Acd. Imper. Vol. 13. Sub Aphidina (group).

Linnaeus (1758) laid the foundation of the present group in the
genus Aphis. Burmeister (1835) applied the term Aphidina to the

TRIBES OF APHIDIDAE 63

family. Koch (1854) indicated the genus Aphis with several other
genera as the tribe Aphiden which is a nomen nudum. Passerini
(1863) considers it under the subfamily name Aphidinae. Thomas
(1878) has the term Aphidini in a tribal sense. Mordwilko (1908)
first used the term Aphidina as a group including the tribes Chaito-
phorini and Aphidini.

Morphological characters. Frontal margin between the antennae
straight or nearly so, or, more commonly, concave, the angles of the
head being drawn out into frontal tubercles on which the antennae are
situated. Antennae usually as long as or longer than the body; spur
always elongated, sometimes exceedingly long. Sensilla of the an-
tennae are sometimes hair-like, usually spine-like, capitate, or spatu-
iate. Prothorax and abdomen often with lateral tubercles like those
found in the Pterocommini. Cornicle cylindrical and long, sometimes
enlarged or widened. Cauda conspicuous and triangular or pointed.
Anal plate entire.

Biological characters. This is the largest group in the family,
containing something like one half of the species. Their classification
is correspondingly difficult and has lagged behind the other groups
which contain a smaller number of forms. The Aphidina contain the
modern, progressive forms that have taken a prominent place in the
insect world and are still expanding. While some continue to return
to woody plants for ovipositing, the majority have become com-
pletely adapted to live on herbaceous plants. They are all strongly
gregarious, forming large colonies.

KEY TO THE TRIBES OF THE APHIDINA
1. Frontal margin nearly straight, or with broad and shallow coneavities; sen-
silla of the antennae short, spine-like and sharp pointed; sometimes long and hair-
like, but never enlarged at apex; third segment of the antennae rarely with sensoria
IDOE ES PUTA. 10. Tribe APHIDINI
—Frontal margin usually deeply concave; sensilla of the antennae capitate or
variously enlarged apically. . . . 2:
2. Frontal margin narrowly coneave, at least in the apterous and larval forms,
due to a glandular swelling of the antennal tubercles; sensilla of the antennae usually
capitate, like those on the front and body in the larval forms. BPD
11. Tribe MYZINI
—Frontal margin broadly and deeply concave in the larval as well as in the adult
forms; sensilla long and spatulate; those of the front, body and in larval forms
usually hair-like; third segment of the antennae usually with sensoria in the

Soom, 3 Gg et 12. Tribe MACROSIPHINI

LOS Ripe Ab HED ENT

Morphological characters. Frontal margin straight, or with shal-
iow concavities, the antennae not situated on conspicuous frontal tuber-
cles. Sensilla of the antennae rarely hair-like as in Chaitophorini,

64 SEVENTEENTH REpoRT STATE ENTOMOLOGIST OF MinnNeEsota—1918

usually short, spine-like and sharply pointed. | Spuriae rarely with
sensoria on the third segment of the antennae. Prothoracic and lateral
tubercles usually present. Cornicles cylindrical, sometimes swollen in
the middle, rarely short and wanting; reticulation open and not form-
ing closed cells as in Macrosiphini. Cauda cone-shaped, triangular or
pointed with a basal clear area.

Biological characters. Size medium to small, never very large
as the Macrosiphini. While some are found on succulent twigs and
leaves of woody plants from which they usually migrate to herbs for
the summer generations, returning in fall to the primary host plant to
oviposit, most of them develop altogether on herbaceous plants. The
variety of plants inhabited is very great; the largest number is con-
fined to a single or at most a few closely related plants. Some seem to
feed indiscriminately on a very large number of different plants.

hs eme MY Z UNG

Morphological characters. Front concavity narrowed, especially
in the larval forms, due to the glandular swellings on the inner side
of the usually short frontal tubercles, which are strongly reticulated
and provided with capitate sensilla like those on the antennae.
Antennae usually much longer than the body; sensilla sometimes very
short but distinctly capitate. In the larval forms the hairs of the body
are also capitate, at least those on the front of the head. Cornicles
Jong and cylindrical, usually club-shaped or enlarged near the apex.
Cauda much as in the Aphidint.

Biological characters. In habitat the present tribe agrees in gen-
eral with the Aphidini and Macrosiphini, but the presence of capitate
hairs on the body in the larval forms indicates a different line of
development and origin from the other two. Similar conditions of
sensilla are found in the Callipterina, with which the Myzini may be
considered to converge, or it is possible that they have diverged from
a common stock of the past.

12. Trrme MACROSIPHINI

Morphological characters. Front deeply and broadly concave,
antennal tubercles usually distinct. Antennae usually much longer
than the body; sensilla usually long and spatulate or widened spear-
like at apex. Sensilla on the head and body usually hair-like, the
same as in larval forms. Cornicles cylindrical, sometimes widest
in the middle; reticulation closed, forming cell-like arrangement on

TRIBES OF APHIDIDAE 65

the distal end of the cornicles. Cauda long, with an apical, narrowed
prolongation turned upward. Spuriae usually provided with sensoria
on the third segment of the antennae.

Biological characters. The present tribe is evidently a continua-
tion of the large race of the Aphidinae, as met with in Calaphidini,
Pterocommini, and Pterochlorini. In habitat they agree with the
Aphidini, most of them are to be found on herbaceous plants.

SUBFAMILY PEMPHIGINAE

Retzius, 1783, DeGeer’s Genera. Sub Abdomen tubereculatum.

Latreille, 1807, Gen. Crust. Vol. 38. Sub Abdomen corniculis tuberculisque nullis.
Leach, 1818, Hort. Soc. Lond. Vol. 38. Sub EHriosoma (genus).

Hartig, 1837, Jahresb. Vol. 1. Sub Pemphigus (genus).

Koch, 1854, Die Pflanzenl. Heft 1. Sub Monokyphonen et Trichotomen.
Passerini, 1868, Aphid. Ital. Sub Pemphiginae (subfamily).

Kirkaldy, 1906, Can. Entom. Vol. 38. Sub Eriosomatinae (subfamily).

Retzius (1783)) and Latreille (1807) foreshadowed the sub-
family by their grouping of the genera of the genus Aphis. Leach
(1818) established the first genus of the group, and Hartig (1837) the
genus Pemphigus which has given name to the subfamily. Koch
(1854) recognized the two subfamilies Monokyphonen and Tricho-
tomen, both of which are nomena nuda. Passerini (1863) first pro-
posed the subfamily Pemphiginae, in which he has been followed by
most writers. Kirkaldy (1906) proposed Eriosomatinae to replace
the term Pemphiginae.

Morphological characters. Frontal margin more or less convex; a
transverse line touching the anterior margin of the eyes, as seen from
below, cuts the antennal attachment (foramen); the antennal fora-
men has moved ventrad so that the antennae are situated between the
eyes and not in front of them as seen in the Aphidinae. Antennae
usually very short, of three to six segments; spur usually very short,
rarely elongated (Mordwilkoja); sensilla few and inconspicuous or
wanting, except in Anoeciini; sensoria usually transverse or annulate,
sometimes circular. Rostrum short or at most moderately long, often
wanting in the true sexes. Venation reduced, media rarely twice
branched, usually with one branch or simple. Cornicles much reduced,
rarely raised above the surface, often wanting. Cauda usually short
and broad. Dermal glands in most cases characteristically arranged
in larger areas along the margin of the abdomen and on the dorsum,
more exceptionally also present as such on the thorax and head.

Biological characters. The Pemphiginae constitute a small group
in comparison with the preceding. Species are not numerous but- so

66 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

greatly differentiated that the number of genera is proportionally great.
The positive characters of the Aphidinae, the development of the
antennae, frontal tubercles, spur, venation, cornicles and cauda, all
appear as negative in the Pemphiginae. Positive characters of the
Pemphiginae are seen in the great development of the dermal glands
arranged into areas, often very conspicuous on account of the secre-
tion of waxy substance under which many of them find protection; gall
structure is also a very positive character of the group. While the
Aphidinae live more or less exposed, depending more on their extra-
ordinary power of reproduction in order to hold their own, the Pem-
phiginae, on the other hand, seek protection by concealing themselves,
under wax, in crevices of bark, in folds of leaves, in true galls, or
underground on roots of plants. This instinct may be considered as the
distinguishing character of the subfamily, which has expressed itself
in all their structures.

KEY TO THE GROUPS OF THE PEMPHIGINAE
1. Fundatrix with six segments to the antennae; sexes with rostrum; found on
bark of woody plants. .. . VI- Group PHYLLAPHIDINA
—-Fundatrix with fewer than six segments to the antennae; sexes usually without
rostrum; usually found on leaves of trees and woody plants. . . . 2.
2. Radial sector arising from the radius back of the stigma, or from the prox-
imal end of the stigma; found on conifers. . . VII. Group MINDARINA
—Radial sector arising from the middle of the stigma; usually some of the gen-
erations are found in twisted or folded leaves or producing true galls on trees or
woody plants. . . 3.
3. TIundatrix with five segments to the antennae; often found in pseudogalls, i.e.,
twisted or folded leaves of trees. . . VIII. Group SCHIZONEURINA
—Fundatrix with four segments to the antennae; usually found in true galls
produced on tender twigs, buds, or leaves of trees. . . . IX. Group PEMPHIGINA

Vike Group PidyY LEAP EIDINA:

Koch, 1854, Die Pflanzenl. Heft 1. Sub Phyllaphiden (tribe).
Passerini, 1868, Aphid. Ital. Sub Lachninae (subfamily).
Mordwilko, 1908, Acad. Imped. Vol. 18. Sub Callipterini (tribe).

Koch (1854) first recognized the present group under the tribal
name Phyllaphiden which is a nomen nudum. Passerini (1863) placed
Koch’s Phyllaphis in the subfamily Lachninae. Mordwilko (1908)
considers it under the tribe Callipterini. Authors up to the present
have considered Phyllaphis under the Aphidinae on account of the
two-branched media, while in other respects it shows the characters of
the true Pemphiginae and should be considered as such.

Morphological characters. Front convex. Antennae short, have
six segments and a very short spur; articulated to the head in shallow
depressions or pockets; sensilla short and few (Phyllaphis), or long

TRIBES OF APHIDIDAE 67

and numerous like a Lachnus (Anoecia) ; marginal sensoria scattered
or in a row close to the primary. Rostrum short or at most moder-
ately long. Fore wings with a twice-branched media, or but one-
branched in the Anoeciini. Cornicles pore-like. Wax glands small
and scattered, or grouped in large lateral areas. Fundatrix with six
segments to the antennae (four in some).

Biological characters. The Phyllaphidina live more or less ex-
posed on twigs or on leaves of woody plants; one species is known
to form a pod-like gall by the folding of the leaf. The present group
may be said to contain the anomalous forms of the Pemphiginae that
show more of the Lachnina and Chaitophorina characters than
is the case with the more typical Pemphiginae. The two tribes included
are not very closely related, and the arrangement may be looked upon
as a provisional one until the life histories of the included forms be-
come better known.

KEY TO THE TRIBES OF THH PHYLLAPHIDINA

1. Media twice branched as in Aphidinae; provided with gland areas secreting

flocculent fibers. . . . 13. Tribe PHYLLAPHIDINI
—Media with one branch only; antennae with long hairs as in Lachnina and
Chaitophorina. ... . .; 14. Tribe ANOECIINI

(32) Tree PR YEEAP ELD INT

Koch, 1857, Die Pflanzenl. Heft 8. Sub Phyllaphis (genus).

Koch (1857) first recognized the genus Phyllaphis, the only rep-
resentative of the tribe at present.

Morphological characters. Front strongly convex. Antennae
short ; secondary sensoria oval or transverse, the marginal close to the
primary in a row; spur of the terminal segment very short. Rostrum
short. Fore wings with a two-branched media as in the Aphidinae.
Cornicles pore-like. Anal plate very large and rounded and with a
pair of lateral papilla. The glandular areas scattered over the dorsum
or collected in two lateral areas on the posterior end of the abdomen.

Biological characters. Members of the present tribe are found
on tender twigs and leaves of trees and woody plants, covered with an
abundant flocculent matter. Very diverse forms have been described
under the genus Phyllaphis, which further study may dispose of other-
wise.

14. Trine ANOECIINI

Koch, 1854, Die Pflanzenl. Heft 1. Sub Schizoneuriden (tribe).
Mordwilko, 1908, Acad. Imper. Vol. 13. Sub Schizoneurina (group).
Tullgren, 1909, Ark. Zool. Vol. 5. Sub Anoeciina (tribe).

68 SEVENTEENTH Report State EntToMoLocist oF MINNEsoTA—1918

Koch (1854) placed the genus Anoecia in the tribe Schizoneuriden
which is a nomen nudum. Mordwilko (1908) has it under the group
name Schizoneurina. Tullgren (1909) placed it as a distinct tribe
under the term Anoeciina. We would consider it as an anomalous
Pemphiginae which, provisionally, may be placed as a tribe in the group
Phyllaphidina.

Morphological characters. Head convex in front; antennae of
six segments and inserted in shallow depressions, moderately long
and provided with long hairs reminding one strongly of the Lachnina ;
spur of the terminal segment short; secondary sensoria circular,
the marginal scattered and of unequal size; reticulation indistinct or
wanting. Rostrum moderately long. Media one-branched as in
Schizoneura. Cornicles pore-like with rimlike margin slightly raised
above the surface. Cauda short and rounded as in Lachnus. Dermal
glands small and scattered, not forming areas. Sexes provided with
rostrum.

Biological characters. The life history is imperfectly known.
They are found inhabiting twigs and leaves of woody plants. It may
be considered an open question if the present tribe would not find a
more natural association with the Chaitophorina, than with the Pem-
phiginae. At least they have little in common with the Schizoneurini.

VII. Group MINDARINA

Koch, 1854, Die Pflanzenl. Heft 1. Sub Schizoneuriden (tribe).
Tullgren, 1909, Ark. Zool. Vol. 5. Sub Mindarina (tribe).

Koch (1854) placed the genus Mindarus with the Schizoneuriden.
Tullgren (1909) considers it as a distinct tribe under the name
Mindarina. We would consider this term as a group coordinate with
the other groups of the subfamily, which at present contain but one
tribe, the Mindarini.

Morphological characters. Front rounded and with a slight
emargination just above the median ocellus. Antennae moderately
long; spur very short; secondary sensoria slightly oval, the marginal
scattered but close to the primary. Rostrum rather long, reaching
the abdomen. Wings large; stigma elongated, extending almost to the
median vein; stigmal vein almost straight and very long, originating
from the radius back of the stigma or from the proximal end of the
stigma; media one-branched as in Schizoneura. Cornicles or pores
very small. Cauda short and pointed, extending beyond the anal plate.
Gland areas when present margined and composed of equal facets.

TRIBES OF APHIDIDAE 69

Biological characters. The habitat of the group is very exception-
al for the Pemphiginae, being found on conifers. The structural char-
acters indicate a very distinct line and origin from the other groups
of the subfamily.

15. Trine MINDARINI

Characters of the tribe are included with those of the group.

VIII. Group SCHIZONEURINA
Koch, 1854, Die Pflanzenl. Heft 1. Sub Schizoneuriden (tribe).
Buckton, 1876, Monogr. Vol. 1. Sub Schizoneurinae (tribe).
Thomas, 1879, Report 8. Sub Schizoneurini (section).
Mordwilko, 1908, Acad. Imper. Vol. 18. Sub Schizoneurina (group).

Koch (1854) first recognized the group under the tribal name
Schizoneuriden with which he included much that is now treated other-
wise; his term is a nomen nudum. Buckton (1876) makes use of the
subfamily term in a tribal sense. Thomas (1879) treats it as a sec-
tion under the subfamily. Mordwilko (1908) first makes use of the
term Schizoneura in a group sense, but included the genera Anoecia
and Mindarus.

Morphological characters. Head not so strongly convex as usual
in the subfamily. Antennae moderately long, composed of six seg-
ments; sensoria strongly transverse and annulate, with the annuli
forming complete rings. Fore wings with media usually one-branched,
sometimes simple; stigma short and pointed distally and stigmal vein
arising from the middle of the same. Cornicles appear as pores or
are wanting. Cauda short and broad as in Lachnus. The gland areas
are usually composed of large facets arranged more or less regularly.
Fundatrices have five segments to the antennae.

Biological characters. The Schizoneurina are characterized by
forming, for some of the generations, pseudogalls by twisting and fold-
ing the leaves, few forming a pouch-like gall. They are all, more or
less, provided with flocculent matter for protection. In size they
are among the largest of the subfamily. Migrations from one food
plant to one different is very common, and not a few attack cultivated
plants, especially roots, and thus are among some of our most destruc-
tive aphids. The favorite habitat of the group for hibernation and for
the spring generations are Ulmus and Fraxinus.

KBY TO THE TRIBES OF THE SCHIZONEURINA

1. The large gland areas confined to the abdomen, or to the thorax and abdomen,
but not found on the head. . . . 16. Tribe SCHIZONEURINI

—Large gland areas present on the head, thorax and abdomen.
1%. Tribe PROCIPHILINI

70 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESoTA—1918

16. TrinE SCHIZONEURINI

Kkoeh, 1854, Die Pflanzenl. Heft 1. Sub Schizoneuriden (tribe).
Thomas, 1879, Report 8. Sub Schizoneurini (section).
Mordwilko, 1908, Acad. Imper. Vol. 138. Sub Schizoneurina (group).

The tribe is essentially the same as the group as treated by various
authors. The recognition of the tribe followed from an attempt to clear
up the close relationship found between the Schizoneurina and Pem-
phigina, associating the Prociphilini as a tribe with the Schizoneurina.

Morphological characters. The distinguishing characters of the
tribe are the absence of gland areas on the head, and the arrangement
of the large facets of the areas in a ring around a central area; the
annuli of the antennae usually form complete rings; media usually
one-branched.

Biological characters. The favorite food habitat for hibernation
and early spring generations seems to be Ulmus.

17. TRipE PROCIPHILINI

Koch, 1854, Die Pflanzenl. Heft 1. Sub Prociphiliden (tribe).

Koch (1854) considers that Prociphilus represents a distinct
tribe which is placed between the Schizoneurini and Pemphigini.
There are some reasons for this. The type genus at present is con-
sidered by most writers under the Pemphigini. In general appearance
and habitat it is a Schizoneurina, in venation it shows close affinities
to the Pemphigina.

Morphological characters. The distinguishing characters are the
presence of obvious gland areas on the head and thorax as well as on
the abdomen, which appears as a distinct line of development from
those of Schizoneurini and Pemphigina. Media is simple and the
venation of the hind wings is triradiate as in the Pemphigini.

Biological characters. The principal food habitat for hibernation
and the spring generations is Fraxinus.

IX. Group PEMPHIGINA

Hartig, 1837, Jahresb. Vol. 1. Sub Pemphigus (genus).

Koch, 1854, Die Pflanzenl. Heft 1. Sub Pemphigiden (tribe).
Thomas, 1879, Report 8. Sub Pemphigini (section).

Buckton, 1881, Monogr. Vol. 38. Sub Pemphiginae (tribe).
Mordwilko, 1908, Acad. Imper. Vol. 18. Sub Pemphigina (group).

Hartig (1837) proposed the first genus that has given the name
to the group as well as the subfamily. Koch (1854) first named the
tribe Pemphigiden which is a nomen nudum. Thomas (1879) gave

TRIBES OF APHIDIDAE 71

itas a section. Mordwilko (1908) first suggested the term Pemphigina
as a group.

Morphological characters. Antennae usually short; sensoria oval
or ring-like as in the preceding group, but the annuli are usually incom-
plete not extending around the segment; in Hormaphidini the annuli
are complete. Media usually simple and not branched; veins of the
hind wings usually arranged in a triradiate fashion. Gland areas less
conspicuous, the facets usually arranged irregularly and are smaller
and more crowded. Cornicles wanting. Fundatrices with only four
segments to the antennae.

Biological characters. The Pemphigina include all the true gall
forms, migrating to various habitats for the summer but returning to
their favorite plants in the fall for hibernation and the gall genera-
tions.

KEY TO THE TRIBES OF THE PEMPHIGINAE

1. Antennae of the migrants and spuriae with six segments; cauda and anal plate

NOLDODVAOUS Sie) a i 18. Tribe PEMPHIGINI
—Antennae of migrants and spuriae with three to five segments; cauda and anal
joey Olonaoisig 5 ia 6 19. Tribe HORMAPHIDINI

18. Tre PEMPHIGINI

Morphological characters. Antennae in migrants and spuriae
composed of six segments; usually very short; sensoria transversely
oval or as incomplete annuli, the ends of which do not meet or fuse.
Media usually simple; cubitus and anal approximate at origin; veins
of hind wings usually arranged in a triradiate fashion. Cornicles
wanting, and cauda inconspicuous.

Biological characters. ‘This tribe includes practically all the gall
forms, that produce typical aphidian galls. The favorite food habitat
for hibernation and for the gall generations appears to be Populus.

19. Trine HORMAPHIDINI

Osten Sacken, 1861, Stett. Ent. Zeit. Vol. 22. Sub Hormaphis (genus).
Borner, 1908, Monogr. Cherm. Sub Hormaphidinae (subfamily).
Mordwilko, 1908, Acad. Imper. Vol. 13. Sub Hormaphidina (group).
Tullgren, 1909, Ark. Zool. Vol. 5. Sub Hormaphidina (tribe).

Osten Sacken (1861) recognized the first genus of the present
tribe. Borner (1908) considers the group to be of subfamily value and
names it Hormaphidinae. Mordwilko takes it as a group under the
subfamily Pemphiginae. Tullgren (1909) considers it as a tribe.

Morphological characters. Antennae of migrants and spuriae
with three to five segments; sensoria annulate and forming complete

72 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

=<

rings. Cornicles wanting. Cauda distinct, enlarged or globate. Anal
plate divided or bilobed as in the Callipterina. Media simple; cubitus
appearing as a branch of the anal; hind wings with one oblique vein.

Biological characters. The Hormaphidini represent the extreme
of the Pemphiginae line of development. Their approach to the
Coccidae may be looked upon as a convergence rather than any close
phylogenetic relationship. Their favorite habitat for hibernation and
gall generations are Hamamelis and Betula.

THE CONFUSED FLOUR BEETLE?

(Tribolium confusum Duval)
By R. N. CHAPMAN

Introduction

Perhaps the most widely distributed insect attacking flour and
other cereals in Minnesota is the confused flour beetle, Tribolium con-
fusum Duval. During the recent war emergency, when substitutes
for wheat flour were being used and every effort was being made to
conserve food, this insect came to the attention of many dealers, bakers,
and householders. This beetle does not claim the attention of the mill-
ers as much as the Mediterranean flour moth, which spins silk and
clogs the machinery, but it is nevertheless a pest which causes them
much loss.

While conducting work on the insects affecting wheat flour and
the so-called wheat flour substitutes, a considerable amount of work
has been done on Tribolium confusum and this paper contains some
of the results. This is to be looked upon as a preliminary report on
work which is still in progress. The fact that the work 1s still in prog-
ress implies that there is no feeling of finality about the results, but it
is thought that the material contained in this paper is suggestive of the
final outcome of the work, and it may be of value to those concerned
with Tribolium confusum.

DESCRIPTION OF THE VARIOUS STAGES

The descriptions of Tribolium confusum in the various stages of
its life history have been published so many times that it is necessary
to do little more than call attention to the accompanying plate which
figures all of the stages (Pl. IV). The figures showing the actual size
of the eggs as compared with the apparent size, when they are covered
with flour, deserve attention. When first deposited, these eggs are
covered with a viscid fluid which causes particles of flour or cereal to
adhere to them, when it hardens, and in many cases it causes the eggs
to adhere to the sides or bottoms of sacks or other containers. The
apparent size of the eggs as they are found in nature depends, therefore,
upon the coarseness of the cereal in which they are laid. A naked egg
such as is figured (Pl. IV Fig. 1) measures 0.6 mm. x 0.3 mm., while
an egg coated with ordinary wheat flour (Fig. 2) measures 0.8 mm.
x 0.6 mm. and represents about the minimum size for a coated egg. In

1 Published with the approval of the Director as Paper No. 154 of the Journal
Series of the Minnesota Agricultural Experiment Station.

73

74 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

all of the coarser cereals the apparent size is much greater, as in bran or
rolled products where it is difficult to separate the eggs from the flakes
of cereal to which they adhere.

The entire larva of the sixth instar is shown in Pl. IV, Fig. 4 and
the heads of larvae of the other five instars are represented in the proper
proportion (Pl. IV Fig. 3 a,b,c,d,e). At first the larval head measures
only 0.1456 mm. at its widest point, and the entire larva is only 0.91 mm.
in length. At each moult the width of the head increases to such an
extent that one can usually determine the instar of a given larva by
measuring the head. As the result of the measurement of a large
number of larvae it was found that the average head measurements for
each of the six instars were 0.1456 mm., 0.182 mm., 0.273 mm., 0.364
mm., 0.546 mm. and 0.728 mm. Occasionally larvae were found which
were almost intermediate between the usual measurements for two
successive instars. In such cases it is not possible to determine with
accuracy to which instar the larva belongs, except by following the in-
dividual life cycle until the time of pupation. However, the records
of such individuals have shown them to be undersized larvae which
continue to lag behind the usual size for each succeeding instar until
they eventually emerge as undersized adults. Therefore it is usually
safe to assume that a larva which has a head measurement interme-
diate between those given for two different instars belongs to the
instar of the next larger head measurement.

The pupae (PI. [IV Fig. 6) have been found to average about 3.858
mm. in length and the average width of the heads, at the widest point,
has been found to be about 0.819 mm. This size is, however, subject
to the same variation as that of the larvae, as has been stated above.
The sexes of the pupae have been distinguished by the external genital
organs which may be seer on the terminal abdominal segment. The
female possesses a pair of appendages on the terminal segment, while
the male presents only indistinct elevations in this region. (Compare
male and temale Plo Pic. 76>)

The variations in the size of the larvae and the pupae result in
corresponding variations in the size of the adults. The measurements
at hand vary from 3.55 mm. to 4.25 mm. The beetle figured (Pl. IV)
is of average size and drawn in proportion to the larvae and the pupa.

Tue Lire History or Tribolium confusum

The exact number of eggs laid by a female beetle has not been
determined with any great accuracy. Ten pairs of adults were isolated
upon their emergence and each pair was placed in a separate container.

‘Tue Conrusep Fiour BEETLE 75

‘hey were placed in flour and kept at a temperature of 26°C. and in an
atmosphere of about 70 per cent of relative humidity. The number of
larvae found after various periods of time were recorded and used as an
index of fecundity. The eggs are so difficult to distinguish when
coated with flour that it has been found that a count of the larvae is
more accurate than one of the eggs. There may be an error due to
eggs which do not hatch and larvae which may die while very small and
are overlooked in the count. After 42 days the ten pairs of adults
had produced the following numbers of larvae: Ist, 41; 2nd, 23; 3rd,
20% 4th, 32> 5th, 50; 6th, 45; 7th, 12; Sth, 7; 9th, 7; 10th, male died, no
larvae.

Some of the eggs are deposited on the sides or bottom of the con-
tainer but the majority are deposited in the flour or cereal itself. Ina
small quantity of flour which had been exposed to beetles, 263 eggs were
found, 8 of which were adhering to the sides of the container, 15 to the
bottom, and the remainder were found by sifting the flour. In this
case the error from overlooking eggs in the sifted flour would be much
greater than that from overlooking eggs on the sides or bottom of the
container, which was of glass.

Upon hatching, the young larvae moult, for the first time, in about
24 hours. The posterior end of the larva adheres to the eggshell for
some time after hatching and the shell may be dragged about by the
larva, if it is at the surface of the flour. In this case the larva may free
itself only when it moults, leaving the skin attached to the eggshell.
During the first instar the larva is whitish, but a short time after the
first moult it assumes a yellowish color. Perhaps the lack of color in
the first instar is due to the short duration of this instar which does
not permit the formation of a sufficient amount of chitin to give color
to the larva.

Fora short time before each moulting, the larva is inactive and the
body is large in proportion to the head. The skin splits dorsally over
the head and the thorax, and the larva emerges. It is at first white,
like the larva of the first instar, but after twenty-four hours it takes
on a yellowish color. Immediately after moulting, when the larva
has expanded as a result of being freed from the old skin, it has often
been observed to remain quiet for a time. When examined in favorable
light during this time of quiet, one may see small bubbles of air passing
in through the oesophagus and back into the proventriculus. The ap-
parent passiveness of the larva makes it appear as if the air were drawn
in by suction as the body expands. The bubbles of air are retained and
may be observed in larvae of almost any age.

76 SEVENTEENTH Report STATE ENTOMOLOGIST OF MInNEsoTA—1918

The feeding activities of the larvae vary with the character of the
material in which they may be found. In coarse, rolled, or ground
cereals, the larvae wrap themselves about the pieces of food and hold
onto them with their legs while they feed. When in finely ground
material they crawl about, feeding as they go. When the material is
very fine and the particles inclined to adhere together and form small
masses, it often causes the larvae much trouble by catching on the hairs
which project from their bodies and impeding their progress.

As the time for pupation approaches, the larvae become inactive
very much as they do just before an ordinary moult, except that the
period of inactivity is of longer duration and they become more great-
ly contracted. The pupa lies ventral side up, often with the old larval
skin attached to the posterior end. It is at first white, later it becomes
yellowish and at the end of its period it is quite dark brown.

Foop Hapsits

Tribolium confusum is known to feed upon a wide range of foods
and is said to exhibit certain preferences. Dean’ states that while
it is primarily a flour pest, it also infests corn meal, cracked wheat,
any dry starchy material, stored peanuts, beans, and even baking
powder, ginger, and cayenne pepper. He states that it may show a
preference for the sweet and more oily low-grade flours, but intimates
that this preference is not a very marked one for the beetles are to be
found in great numbers in the best patent flours. The general state-
ment has often been made that insects prefer coarse cereals of a low
grade.

In order to determine whether certain preferences actually exist,
two lines of investigation have been pursued. Stocks of flour and
ground cereals have been examined in storehouses to determine the
percentage of infestation in the various products. In the laboratory,
experimental methods have been employed to study the relative sus-
ceptibility of the various flours and cereals under controlled condi-
tions.

THE RELATIVE INFESTATION OF WHEAT FLOUR AND WHEAT FLOUR
SUBSTITUTES

In the examination of the cereals in the storehouses a uniform
method of sampling has been adopted. A brass tube 2 cm. in diameter
and 40 cm. in length was sharpened at one end and graduated on the

1 Bull. 189, Kansas State Agr. Exp. Sta. 1913.

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78 SEVENTEENTH Report STATE ENtToMoLocist oF MINNEsoTA—1918

outside to read in cc. This tube was thrust in between the stitches at
the end of the flour sack and could be withdrawn full of flour without
otherwise disturbing the sack. The sample of flour was then weighed
and sifted. It was found that when the tube was slowly turned in
one direction as it was being pushed in, the sample withdrawn would
be of quite uniform weight.

Four samples were usually taken from the flour next to the out-
side of the sack. The sample was sifted with an Excelsior testing set.’
The size of the standard bolting cloth varied with the character of the
material under examination, but No. 5 was used whenever possible.
After counting and removing the insects, the residue on the bolting
cloth was taken to the laboratory and incubated to determine whether
it contained eggs.

The history of the flour, in so far as it could be obtained, was
tabulated on the record sheet for use in determining where the prod-
ucts became infested. All of the establishments recorded on the accom-
panying table were visited without any advance knowledge of the pres-
ence of insects. This investigation was undertaken so late in the
season that insufficient material was examined to give significance to
the results. However, the results are given here, for they are sug-
gestive of a line of work which will add to our knowledge of relative
infestation. (See Records.)

THE RELATIVE SUSCEPTIBILITY OF WHEAT FLOUR AND WHEAT
FLourR SUBSTITUTES

The experimental work on the relative susceptibility of the various
flours and cereals to Tribolium confusum has proceeded upon the as-
sumption that other things being equal, susceptibility may influence the
number of insects which enter a flour in the first place ; or the rate of de-
velopment of the insects after entrance may lead to their accumulation
in great numbers. In the first case it might be possible to account for
the great number of insects in a certain flour by the fact that a great
number chose to enter it in the first place. In the second case, assum-
ing that equal numbers of insects entered each of a number of foods,
the shortening of the life cycle in one of these would, in time, give
it the appearance of being more susceptible than any of the other
foods.

2 The Excelsior testing set, manufactured by Hammond-Humberg Co., Minneapolis,
Minn., consists of a sifting frame together with the silk bolting cloths No. 0000
standard to No. 16 standard inclusive.

THE CoNFUSED FLoUR BEETLE 79

In consideration of the first proposition, various flours were
placed in cylindrical jars with removable partitions, which divided the
jars into five equal sectors. [qual amounts of the five cereals to be
used in the experiment were placed in the various sectors of the jar
and the partitions were removed. The surface was then made as
smooth as possible without packing the cereal and a small depression
was formed in the center. The jars used were 10.5 cm. in diameter
and the cereal was about three cm. in depth, except in Series 3 as
recorded below. The beetles were placed in the depression in the
center of the jar and, being thus surrounded by equal parts of the five
different cereals, they were free to express their choice.

The experiments were carried out in the dark in order to eliminate
light as a factor. The duration of the experiments varied from a few
hours to several days, the length of time making little difference after
the first few hours when the insects were exploring about. When the
time between examinations extended into weeks another factor entered
in, as will be shown later. Observations were made by replacing the
partitions and removing the different foods to count the number of
insects contained in them. When one hundred insects were used, the
number found in any one flour would be the percentage of relative sus-
ceptibility of that flour as compared with the other flours used in the
experiment. In making the counts, beetles which remained in the center
and expressed no choice were disregarded. Consequently the figures
given for the counts do not always total one hundred. In all cases
where the average percentage is given the actual percentage of the
beetles which did express a choice has been computed.

The relative susceptibility of five grades of wheat flour was
studied in this way. [Fach series of experiments was performed with
a different lot of beetles. The following results are the averages for
each of the five series.

EXPERIMENTS WitH ApuLt Tribolium Confusum

Series 1 Series 2 Series 38 Series 4 Series 5
Average of Average of Average of Average of Average of

Flour Scounts 5counts 6counts 3 counts 3 counts

per cent per cent percent percent per cent
Binst muddilings i... . 12.092 17.504 ese 11.734 112733
Irie GANGS ss oce0case 12.092 10.914 6.52 14.064 14.063

First low grade .:..... 17.812 9.804 1.92 13.734 15.20

IDES TAMbIMES sis soc coe 20.672 14.204 1.92 17.064 16.330
Biraiiipe se teebay seis oem 37.332 47.514 82.320 43.404 43.730

These flours vary in refinement from the fine middlings to the
bran. In Series 3 the materials were only 1 cm. in depth, which may
account for the difference of percentages.

80 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

It will be noticed that the bran contained, on an average, about
twice as many beetles as would be expected if they were equally dis-
tributed among the five flours which were used in the experiments.
All of the other grades of flour show such slight variations from the
expectation that the data proved nothing with regard to selection on
the part of the beetles.

The invasion experiments with the larvae showed no selection.
The percentages are all so near the expected twenty per cent that the
differences are to be explained as chance variations.

Series 1 Series 2
Average of Average of

Flour 5 counts 7 counts
per cent per cent

Bins middlines eee sa. oe 17.931 18.588
ESS TASIZIMGS cso ire 17.373 17.247
Binst lows senade) je. cmc 24.350 27233
Binst failinas) o-satee dee. 22.435 20.272
Bare te hs cues Srey son 17.921 16.481

The study of the susceptibility of the wheat flour substitutes did
not yield any conclusive evidence of preference on the part of the
beetles. The results at hand show such an amount of variation that
conclusions must await the results of a more extended series of experi-
ments. In this paper two series of experiments will be introduced for
comparison with those in which the wheat products were used. Only
four wheat flour substitutes were used and the first low grade wheat
flour was included for the sake of the comparison with the wheat flour

series.

First Second Third
Flour eount count eount

Pirstilow erade see scene 8 19 19

RICE at Oli kere. Aa 24 25 33

Barleyanl Own seer ae sean 16 17 17

White rye flour .........: 31 33 11

Wihiterconnth ounisesmeacre 21 22 20

When rye meal was bolted through a No. 2 bolting cloth and the
bran retained by the cloth was substituted for the first low grade wheat
flour, the results were more decisive.

First Second Third
Flour count count count
Ryesbpran: 64 see oe 40 33 35
Race silos ss eee 19 17 18
Batley tones ae ee 9 11 if
Rye! dG 95: areemor. 14 ZA 10
Cornel oun ene 19 17 18

In this series there is a rather definite percentage of choice so far
as the rye bran is concerned. As with the wheat flours it is the coarse,

Tue ConFuSsED FLourR BEETLE 81

flaky material which is chosen by the beetles. But when cornmeal was
introduced no choice for it was indicated. Unfortunately the experi-
ments in which the cornmeal was included were not properly checked
and will not be included here.

Since the above experiments seemed to indicate that coarseness
was a factor in invasion, an experiment was tried in which the foods
differed in respect to this factor, but were of the same nutritive value.
The bran was sifted and that which was retained by a No. 2 bolting
cloth was divided into two portions, one which was left in the original
coarse condition, and the other which was ground until it would pass
through a No. 5 bolting cloth. The fine material was placed in one
half of a container and the coarse material in the other half while the
beetles were placed in a depression in the center, as in the previous ex-
periments. An average of 62 per cent of the beetles was found in the
coarse material.

For a further check on the factor of coarseness, an experiment
was planned to exclude the factor of nutrition. For this purpose pine
sawdust, which had been treated with alcohol to dissolve out the oils,
was employed. A coarse grade, which passed through a No. 0000
bolting cloth but which was retained over a No. 00 cloth was placed in
one fifth of the jar and the other four fifths of the jar contained fine
sawdust which passed through a No. 2 bolting cloth. The experiments
were manipulated in the same manner as when the five grades of wheat
flour were used. The results were surprisingly like those obtained with
the wheat flours.

First Second Third

Material count count count
Fine sawdust No.1 .... 25 11 10
Fine sawdust No.2 .... 28 8 5
Fine sawdust No.3 .... 11 13 12
Fine sawdust No. 4 .... 2 20 23
(C@girse Sainyalotse .oocdec 34 48 49

These results make it evident that the coarseness of the flour or
cereal may be the dominant factor concerned in invasion by insects.
The fact that similar results were not obtained with cornmeal makes
it seem evident that this factor is concerned with the tactile responses
of the beetles. The beetles respond to the flaky materials between
which they can penetrate very readily while the more granular material
does not offer the same stimulus, because the finer particles fill in the
spaces between the larger particles and thus offer much less favorable
opportunities for the beetles to enter the material.

82 SEVENTEENTH Report STATE ENtomMotocist oF MrInNesota—1918

The influence of nutrition in determining the relative invasion of
the wheat flours has not been measureable as a factor in these experi-
ments. To determine whether the method would indicate differences
of nutritive value, coarse sawdust was introduced in place of the bran
in the wheat flour series and it was found to contain a varying number
of beetles, principally at the edges where the sawdust and flour be-
came slightly mixed. It averaged only 6 per cent of the beetles, which
makes it very evident that the method used does measure the nutritive
difference between the wheat flours and the sawdust.

When an experiment has stood for a period of several weeks it
has been found that the decisive differences between the flaky and fine
materials tend to disappear. Thus the ratio between the percentages
of the coarse and fine bran material was 60 per cent and 40 per cent
examined every 48 hours, but when the experiment was left for a
period of 26 days it was found that the fine material, contrary to the
previous findings, contained 53 per cent of the beetles and the coarse
material contained 47 per cent. An examination of the material after
it has been exposed to a large number of beetles for an extended length
of time shows that it has been burrowed by the beetles until it is
‘“honeycombed” and is apparently more attractive to the insects. The
beetles may be driven by competition to enter the fine flour and thereby
alter it and make it a more favorable environment resembling a flaky
material so far as their tactile responses are concerned.

In consideration of the relative development of the beetles in the
various wheat flours and the wheat flour substitutes, an attempt was
made to determine whether there was a difference in the velocity of de-
velopment in the various foods, and, 1f so, whether this difference was
sufficient to account for more insects being found in certain of the foods
than in others. The experiments were all carried out under controlled
conditions and all of the experiments of each series were carried on
simultaneously so that all of the results were directly comparable.

The first series was started by exposing the material to a number
of beetles for twenty-four hours and then removing the beetles. Since
no attempt was made to determine the sex of the beetles used, a defi-
nite number of eggs could not be expected, but from a dozen or more
beetles, a few eggs could be depended upon. The vials containing
the material and eggs were placed in the dark at a known temperature
and humidity. The material was examined daily except when the task
of making the records made it impossible for all of the material to be
studied each day.

The date of hatching of the eggs is taken from the first daily ex-

Tue ConFrusep FLour BEETLE 83

amination at which larvae were observed. Thereafter the larvae were
measured at each examination and the measurement of the head, at the
point of its greatest width, and the total length of the larva were re-
corded.

The graphs (Plates II and III) are arranged in columns, with the
records of the individual beetles placed one above the other in each col-
umn. The graphs of the beetles in the various foods are grouped
together. The time in days represented by the vertical divisions of
the chart, each large division representing ten days; and the stages of
the life cycle of the beetles are represented by the horizontal divisions
of the chart. The daily temperature is recorded at the top of each
column of graphs.

The first day of the egg stage is represented by an open square,
because the exact time of oviposition is not known within twenty-four
hours. Thereafter the definite records are represented by solid black
squares. Upon the appearance of the larva the record moves up one
space to record the beginning of the next stage of the life cycle. At
the time of each moult, as evidenced by the increase in the head meas-
urement, the record moves up one space. At the end of the record the
appearance of the adult is recorded with an “X.” If the record of the
emergence of the adult is not known within twenty-four hours, the
“X” is placed in an open square.

When open squares are used in the records, they are placed hypo-
thetically from a study of the complete records of other individuals.
At the top of the record for each of the wheat flour groups, the record
of the checks is shown. These beetles were subjected to the same
conditions as the others except that they were not interrupted for the
taking of measurements. Consequently the check records are straight
lines and show only the duration of the entire life cycles.

It will be noticed that the records are very similar for the first
twenty-two days and that the variations in the length of the stages
come in the latter part of the larval life, particularly during the last
instar. While there is considerable variation among the larvae feed-
ing on the different wheat flours, it is to be noted that all of the checks
are of the same length. The variations must, therefore, be attributed
to other factors than the nutritive value of the food. The fall of tem-
perature toward the end of the experiment will, of course, account for
the prolongation of stages then incomplete, but would not account for
the total difference between the long and short stages. .

The records of the beetles fed on the wheat flour substitutes show
the greatest variation, yet, even here, there are some individuals in

ist oF Minnesota—l918

a

ENTOMOLOC

SPORT STATE

E

R

NTEENTH

DEVE

o

&4

eugceeeeauuaeet

Time in Days.-

!

II

PLATE

1M

the small squares, reading

The record of each beetle is recorded in the ten spaces between the

Temperature is indicated by the dotted line
by

days is indicated

raphic comparison of the length of various stages in the life cycle of Tribol
Time in

the plate.

ALES

confuswm under different food cenditions.

across the top of the plate.

across

CoNFUSED FLouR BEETLE

THE

Til

PLATE

a small square,

The first square represents

ach stage of the life cyele is indicated by

oy

I

heavy horizontal lines.

hth square repre-

o
5S

x larval instars, the ei

i

x represents the s

i

sents the pupal stage, and the ninth square represents the emergence of the adult beetle.

starting with each heavy line and reading up the plate.

the egg stage, the next s

86 SEVENTEENTH Report STATE ENtomotocist oF Mrnnesota—1918

each group which do not differ greatly from some of the individuals in
the wheat flour groups. The group of beetles fed on rice flour show
the greatest prolongation as a group, while the longest individual life
cycle is found in the corn flour group.

Another series of experiments has been carried out at a tempera-
ture of 26°C in which the total length of the life cycle was recorded
and no attempt was made to determine the length of the various stages.
Here, as in the checks for the wheat flours of the first experiment, the
records of the insects in the different foods are much more uniform.
The time from the hatching of the eggs until the emergence of the first
adult was 37 days in the middlings, 39 in the sizings, 38 in the low
grade, 38 in the tailings, and 39 in the bran. In the other foods it
was 39 days in the rye flour, 38 in the barley flour, 40 in the corn flour,
and 47 in the rice flour. The shortest time in the rice flour was thus
about 20 per cent longer than in the middlings. But all of the larvae
in the rice flour had pupated by the end of 47 days while one of the
larvae in the middlings was still feeding at the end of this period.

The rate of development of the beetles may be influenced by the
relative fecundity of the beetles in the various foods. The number
of eggs deposited by females which were restricted to certain foods
have given the following results: middlings, 32; sizings, 34; low grade,
41; tailings, 32; bran, 20; barley flour, 50; rye flour, 20; corn flour, 45;
rice flour, 12. The beetles studied have shown such an amount of
variation among the different individuals that the limited data at hand
cannot be considered sufficient for determining the influence of dif-
ferent foods upon fecundity. Such conclusions must await the com-
pletion of a series of experiments involving many individuals reared in
certain foods for many generations.

The analysis of the factors influencing relative development will
require a more extensive study, but there are certain facts which are
brought out by the work thus far. There are individual variations
which seem to be independent of the food on which the insects are
feeding. It is possible that the different portions of the kernels which
constitute the flours are unequally distributed in the mixture as it exists
in market form and that some individuals, by chance, obtain a ration
which accelerates growth, while other individuals, by chance, obtain a
diet which is less favorable for rapid growth.

The observations show that, in general, the beetles with the pro-
longed stages encountered mechanical difficulties. They were found
with particles of flour attached to them and all their efforts for

THE CoNFUSED FLouR BEETLE 87

a time devoted to freeing themselves. Mortality in many cases seemed
to be due to these mechanical difficulties.

From the records at hand the percentages of mortality are as fol-
lows: for the wheat flours, first middlings, 40 per cent; first sizings,
33 per cent; first low grade, 40 per cent; first tailings, 40 per cent; bran,
32 per cent; for the other materials, barley flour, 50 per cent; steele-
cut oats, 32 per cent; rye flour, 55 per cent; white corn flour, 56 per
cent; rice flour, 12 per cent. These percentages are taken from mea-
ger data and should not be looked upon as conclusive vital statistics,
altho they are the result of controlled conditions which approximate
the optimum.

METHOpDS OF CONTROL

The control of Tribolium confusum is the problem of preventing it
from invading stored food products. In cases where the infestation
already exists it may be necessary to resort to some method of
“sterilizing” the infested products.

So little difference has been found in the susceptibility of the vari-
ous food products studied in this connection that the number of insects
which may be found in a given product probably depends very largely
upon the opportunities which the beetles are afforded to invade the
product. Flour on the floors of mills and storehouses supports a small
population of beetles which invade sacks of flour and are then trans-
ported to other storehouses where the infestation may spread. Among
the many instances of this which have been found was that of a large
warehouse which had become badly infested from a single shipment
of infested rolled rye. The flour which was stored closest to the rolled
rye contained the heaviest infestation, and that more distant from it
contained proportionately fewer beetles.

An infested storeroom or mill may be freed from insects by fumi-
gation with hydrocyanic acid gas, or it may be heated to the fatal tem-
perature for insects. Both of these methods have been described by
Dean in Bulletin 189, Kansas State Agricultural Experiment Station,
Manhattan, Kansas.

The fumigation should not be undertaken without detailed direc-
tions and the temperature conditions must be favorable. Furthermore
it requires the shutting down of the mill for several days and always in-
volves a certain amount of risk on the part of the operator. Dean also
states that the gas does not penetrate the accumulations of flour and
the cracks, which harbor the insects, so well as the heat does.

When heat is used to kill the insects in a building it is necessary

88 SEVENTEENTH Report StaTtE Entomotocist or MinNEsotA—1918

to obtain a temperature of 48°C (120°F) and maintain this tempera-
ture until the heat has penetrated all of the flour or grain which may
contain insects. In Kansas it is possible to do this during warm sum-
mer weather, when there is a sufficient amount of radiation, by turn-
ing on the steam Saturday evening and keeping it on until late Sunday
night. In this way the mill is cooled down by Monday morning and no
time is lost. Experiments in Minnesota have shown that it is necessary
to have increased radiation in order to attain the proper temperature.
However, this would seem to be a promising field for experiments.

It has been found that infestations are often spread by the refill-
ing of flour sacks which have not been thoroly cleaned. In several in-
stances where storerooms were found to be free from any source of
infestation the cause of the large number of beetles present in the flour
was traced directly to the refilling of uncleaned flour sacks. When a
method of heating the flour sacks in the oven was adopted, the trouble
ceased. It was found that the empty sacks could be placed in an ordi-
nary baker’s oven at the usual temperature of 230°C (about 450°F)
and left for about five minutes, when all of the insects would be killed,
provided the sacks were not more than three layers deep. As a pre-
caution against scorching of the sacks they should be placed on pans
or boards to keep them from coming in contact with the oven. Care
should also be used not to let the sacks remain in the oven longer than
five minutes at the temperature indicated above. Boxes and other
utensils which are used about a bake shop and which may harbor in-
sects, have also been heated in the oven and all stages of insects killed.

Large amounts of flour or other stored food products may be
freed from Tribolium confusum by fumigation or by sifting. Carbon
disulphide or hydrocyanic acid gas (described above) may be used for
this purpose. The carbon disulphide is placed in shallow dishes on
top of the material to be fumigated and the liquid evaporates. The
fumes, which are heavier than air, settle down into the material and
kill all insects which may be present. This material is very inflam-
mable when mixed with air and should never be used near a fire. The
quantities recommended are about one pound to every 100 cubic feet
of space. When the material is placed in a tight barrel, about one cup-
ful of the liquid will be required. The receptacle must be tightly cov-
ered and left for a day or more, after which the material should be
well aired. Farmers’ Bulletin 799, United States Department of
Agriculture, Washington, D. C., contains much information with re-
gard to the use of carbon disulphide.

89

Experiments with the eggs of Tribolium

confusum have shown that the size of bolting cloth which would re-
Do

remove the beetles only when it is possible to
tain them depended upon the material adhering to the eggs (Tig.

Tue Conrusep Flour BEETLE

Sifting of flour will
pass the material through a bolting cloth which is fine enough to ex-

clude all stages of the beeties.

2).

a
deol

pte

El
Cow

geee

Time in Minutes

eee EEE
alelmielalalal
LoS.
|
HH { FEEE Po,
[ele | SSIES),
eee
EEEEeee
al Pes.
bya Le)
eee
PEE to
EEE HI
cS}
T wel

3
Curves showing the rise of temperature in the top, center,

|

i
Bet
ree Sasa ot
1 if

7:17-Sm

and bottom of
s cold at the start, the cereal was

s as low as it would burn for fifteen minutes.

The oven wa

Mires lay
a pan of cereal heated in a gas oven.

two inches deep in the pan, and the fire wai

90 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Experiments in passing cggs through bolting cloths gave the following
results :

No. 0 standard bolting cloth passed 11 eggs taken from ordinary
wheat flour and retained 1 which was attached to some coarse material.

No. 1 bolting cloth—3 eggs were retained, 4+ passed through
readily, and 3 others were forced through without injury.

No. 2 bolting cloth—retained 5 coated eggs, and 1 naked egg was
forced through endwise.

No. 3 bolting cloth—no eggs were passed through without injury.

The experiments with the larvae gave the following results:

No. 0000 bolting cloth—larvae of all instars passed through.

No. 000 bolting cloth—larvae of the first five instars passed
through readily, 7 larvae of the sixth instar crawled through by exert-
ing some force.

No. 00 bolting cloth—1 larva of the sixth instar passed through
with great difficulty. Larvae of the fifth instar also required some
effort to get through the meshes.

No. O bolting cloth—retained 1 larva of the fourth instar while
3 larvae of this instar and 3 of the fifth instar passed through, the lat-
ter with much effort.

No. 1 bolting cloth—1 larva of the fourth instar passed through,
all others of this and succeeding instars were retained. The younger
larvae all passed through.

No. 2 bolting cloth—2 larvae of the fourth instar passed through
with great effort. Smaller ones passed through and the larger ones
were retained.

No. 3 bolting cloth—2 larvae of the third instar passed through
with great effort, all others of this instar were retained.

No. 4 bolting cloth—3 larvae of the third instar succeeded in
passing through.

No. 5 bolting cloth—3 larvae of the third instar passed through
with effort as before.

No. 6 bolting cloth—1 larva intermediate between the second and
third instars, passed through, 6 larvae of the second instar were re-
tained.

No. 7 bolting cloth—retained 2 larvae of the second instar and 5
passed through after a struggle.

No. 8 bolting cloth—1 larva of the first instar succeeded in getting
through, while all others were retained.

It is evident that larvae may pass through any bolting cloth coarser
than No. 6 and that No. 9 must be used to be absolutely safe. This

Tue CoNnFuSED FLouR BEETLE 91

means that sifting will remove the beetles from only the higher grade
flours. It also indicates that in the process of milling eggs or young
larvae might be included in the coarser and lower grade flours while
they might be excluded from the finer, high grade flours.

For small amounts of flour the safest and simplest method is to
heat it in the oven. This may be done by placing the flour or cereal a
little less than two inches deep in pans and keeping the fire as low as it
will burn well until the surface of the cereal reaches a temperature
of 85°C (185°F). If a gas, gasoline, or kerosene stove is used, the
fire should be turned out and the oven left closed for thirty minutes
after the above temperature has been reached. If a wood or coal stove
is used, the oven door should be left open and the fire kept as low
as possible during the thirty minutes after obtaining the desired
temperature. It is necessary that the fire should be kept low in order to
allow as much time as possible for the heat to penetrate to the center
of the cereal before the top or bottom of the cereal reaches a tempera-
ture which will injure it. It has been stated that some materials will be
injured if heated to 96°C.

Stirring the material when it has reached 85°C helps to distribute
the heat. Figure 15 shows the curves for the temperatures of the top,
bottom, and center of a pan of cereal heated as described above. It will
be noticed that it required fifteen minutes for the top of the cereal to
reach a temperature of 85°C. The temperature of the bottom of the
cereal follows that of the top, while the temperature of the center lags
behind. But even the temperature of the center passes well above the
fatal temperature for the beetles, which is about 48°C. At the same
time the top of the cereal does not reach the temperature which will in-
pure it.

When the heat treatment is followed by careful storing in tight,
clean containers, the possibility of loss due to Tribolium confusum is
eliminated. The heating of all cereals as soon as they are brought into
the house, in warm weather, is strongly recommended. Eggs or small
larvae may be present in the cereal when a close search fails to reveal
them, and a little time spent in heating the cereal will eliminate the
danger of infesting the home. It is much easier to keep the beetles
out than it is to get them out if they once get in.

If a suitable thermometer is not at hand, a heat testing wax is
on the market which is standardized to melt at the proper temperature.
If the grocer does not have the wax he may get it from his wholesale
dealer. A box of the wax costs only five cents and contains nearly a

year’s supply.

92 SEVENTEENTH Report STATE ENtToMoLocist oF MinNEsoTA—1918

SUMMARY

1. The larval life of Tribolium confusum is composed of six
instars which may be distinguished by the measurement of the head at
its widest point.

2. A method of examining flour or cereal to determine the
amount of infestation, has been adopted which makes it possible to
express the results in terms of the beetles in a given weight of flour.
For this purpose the sample of flour is taken from the sack by means
of a brass tube which may be thrust in between the stitches at the end
of the sack. The sample of flour withdrawn is then weighed and
sifted through a bolting cloth and the residue retained by the bolting
cloth is incubated to determine whether any eggs are present. The
number of insects present may be expressed by a computation of the
number per kilogram of material.

3. A study of the relative susceptibility of various wheat flours
and wheat flour substitutes by means of a jar with removable partitions,
has made it possible to determine the number of insects attracted to
each of a number of flours used in the experiment. The results of
this method make it seem that coarse flaky material is slightly more
attractive than fine or granular material. However, by crawling
through a fine flour the beetles cause it to become honeycombed and
thereafter the beetles enter it as readily as they do the coarse flaky
material.

4. A comparison of the rates of development of beetles in various
foods, under uniform conditions, has shown that the life cycle may be
slightly longer in some foods than in others and that this difference in
the rate of development is confined very largely to the last larval
instar.

5. The differences in the relative infestation which workers have
noticed in mills are not accounted for by the experimental methods
employed in this work but it is suggested that these differences may
be due to the methods of handling various products which give the
beetles a better opportunity to enter some of them than others.

6. Materials which have passed through a No. 3 bolting cloth will
contain no eggs. To exclude the larvae of the first instar a No. 9 bolt-
ing cloth must be used.

7. The heating of flour sacks before they are refilled has been
found to control the beetles, when accompanied by a general practice of
cleanliness about storerooms.

THE CoNFUSED FLouR BEETLE 93

8. A convenient method has been devised for treating small
amounts of flour to kill any eggs or other stages of insects which may
be present. It has been found that when flour is less than two inches
deep in pans, it may be slowly heated in an oven until the surface of the
flour reaches a temperature of 85°C and then, after remaining in the
oven for thirty minutes longer with the heat turned off, the flour will
have attained a minimum temperature well above the fatal temperature
for the beetles while the maximum temperature is well below one which
will cause injury to the cereal.

94

SEVENTEENTH Report STATE ENToMoLoGIsT oF MrINnNEsoTA—1918

Fig.
Vig.
Fig.
Fig.
Fig.
Fig.

Fig.

TIS? DUR oto

PLATE IV

Naked egg. x17
Begg coated with flour. x17.

Heads of larvae of first, second, third, fourth and fifth instars.

Mature larva of the sixth instar. x17

Larval leg.

Female pupa and terminal segments of male pupa. x17.
Adult Tribolium confuswm Duval. x17,

Self

EE CLOVER-SEED CHALE»:
Bruchophagus funebris Howard
By WarRREN WILLIAMSON

The clover seed chalcid first attracted the attention of entomologists
in 1879 when Prof. J. H. Comstock at Washington, D. C., reared it from
clover heads infested with the clover seed midge, Dasyneura legumini-
cola Lint. He believed it to be parasitic upon the latter species. Speci-
mens were submitted to L. O. Howard who described it as a new
species, naming it Eurytoma funebris. Dr. W. H. Ashmead in 1894
referred the species to a new genus which he named Bruchophagus,
believing all the species of this genus to be parasitic on the seed weevils,
Bruchidae. Evidently the clover seed chalcid was generally considered
as a parasite until Dr. A. D. Hopkins (1898), in West Virginia, proved
that instead of being a parasite, it is itself a serious clover seed pest.

Other workers whose publications have contributed much to our
knowledge of the subject are R. H. Pettit of Michigan, E. G. S. Titus
of the Bureau of Entomology, who collected data on the distribution
of the pest as well as contributing other important data, F. M. Webster,
Bureau of Entomology, who published the first illustrations, Dr. J. W.
Folsom of Illinois who gave the most complete account of the species
yet published, and T. D. Urbahns who gave, in Farmers’ Bulletin
636, the most recent account of original work with control methods.

The study of the clover seed
chalcid in Minnesota was begun
in 1907 by A. G. Ruggles and
continued by him until 1910 when
T. D. Urbahns had charge of the
investigations for one year. The
work of the writer was begun in
July, 1911, but after 1914 it was
so frequently interrupted by
others duties that it was finally
discontinued altogether.

DESCRIPTION OF INSECT
The following description of

the different stages is quoted
Fig. 16. Clover head showing openings i Be
‘made by adult chalcids in emerging. if from Folsom (1909).

1 Published with the approval of the Director as Paper No. 155 of the Journal
Series of the Minnesota Agricultural Experiment Station.

95

96 SEVENTEENTH Report STATE ENtomMoLocist oF MrInNesota—1918

“The adult 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 sur-
roundings, however, 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 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. partienlan
species, funebris, is black and
non-metallic. Eyes dark brown,

\ antennae almost as long as the
thorax; flagellum of eight seg-
ments, there being five in the
funicle and three in the club; the

funicle segments have each a

Fig. 17. Female chalcid ovipositing. 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 tibiae, 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
jong as the thorax, and its fourth segment is the largest.

“The female is like the male in coloration but is larger, with these

THE CLover SEED CHALCID 97

distinctive characters. Antennal segments not petiolate, and without

the long hairs; flagellum of nine segments, the funicle having six and

Fig. 18. Male of B. fuwnebris.

the club three. Abdomen not
pedunculate, longer than the
thorax, with the fourth and
fifth segments short and sub-
equal, and with a light brown
pointed extremity—a part of
the ovipositor.

“The egg is broadly ellip-
tical 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 trans-
lucent, whitish, and smooth;
within a day, the appendage
shrinks and turns brown.

“The maggot-like larva is

white, stout, footless, with a small head; length when full grown, 1.5
to2 mm. The larva shows few distinctive characters, tho it 1s stouter

and less active than parasitic larvae of the same family.

“The pupa is for a time white, but darkens
as the color of the imago develops; length -

Oem.

It may be noted in addition to the above de- (oe \

scription of the larva that when very young
and feeding upon green seed contents, it has a
greenish tinge. The full grown larva has
brown mandibles, each with a tooth on its
inner edge.

SEASONAL History AND HABITS

The life history of Bruchophagus funebris
consists of two generations in a year with over-
lapping individuals producing a frequent third

ig.

il),

generation. The first brood of adults appears in June.
posit in the soft green seeds of the first crop and of stray clover plants
along roads. The time required for the eggs to hatch varies. Accord-

Egg of B. fune-
biis.

Females ovi-

98 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

ing to Urbahns (1914), under favorable temperatures the larvae begin
feeding in about a week after the eggs have been deposited. If condi-
tions are extremely favorable, the

larvae complete their growth in about

twelve or fourteen days, enter the ay
pupal stage for four or five days and /| S. \
emerge as adults. The larval and ee Sie Aa aeeee Pies
pupal stage are spent entirely within

the infested seed. The second and a partial third brood overlap in July
and August. Females oviposit in the late blossoms or seed crops. A
few of these become adult before winter, but soon perish. They hiber-
nate mostly as full-grown larvae within the seeds, enter a short pupal
stage in the spring and appear as adults in June.

Fig. 21. Larvae of B. funebris in clover seeds. (After Urbahns.)

EMERGENCE OF ADULTS

In 1911 the clover seed chalcid was very rare in the southern
half of Minnesota owing to the failure of the clover crop on account of
the unusually dry season. Observations were made in the vicinity of
Duluth from July 15 to October 15. Adult chalcids were not found
until July 21. They reached their maximum abundance about August
15, then gradually decreased in numbers and were not found in the
fields after September 25. A few specimens were found at Bemidji,
September 21.

THE CLoverR SEED CHALCID 99

In 1912, the weather conditions being favorable for the growth
of red clover, the chalcids got another start in the southern half of the
state. The first specimen was taken June 1 at University Farm, Saint
Paul. This undoubtedly represented the first generation for the year.
So few could be found that we cannot say when this generation reached
its maximum abundance. The second generation appeared in breeding
cages on July 5, emerging rapidly until July 9, then slowly and in small
numbers during the remainder of the month.

In 1912, also, observations and collections were made in the south-
eastern part of the state, Olmsted and Fillmore counties. No data
were secured on the emergence of the first generation. Clover heads
collected in that region on August 8 and 9 and placed in the insectary
at University Farm gave adults from August 19 to September 27.
Heads collected September 11 and 12 gave adults from September 24
to November 16. In all, 217 individuals were reared, two-thirds of
which emerged before September 1, and these came from the heads
collected August 9 and 10. The period of most numerous emergence
for the year in Olmsted and Fillmore counties was probably during the
last week of August.

In Wadena county, in 1912, we were not able to observe the
emergence of the first generation, but from breeding cage records and
field collections it appears that of the succeeding generation a very few
adults were out from August 15 to 25, then a rapid increase, a large
number emerging until September 25, then a rapid falling off in early
October.

In the season of 1913 in the vicinity of University Farm, adults
appeared June 12, a very few until June 18, then no more until July
10. A few appeared during July and until August 18 when there was
a sudden increase and many emerged until September 6. After that a
few during the remainder of the month. Clover heads taken in the
previous September in Fillmore and Olmsted counties gave the first
adult June 12 and the last July 1. The period of most numerous
emergence was from June 17 to June 21.

Clover heads from Wadena county collected in September, 1912,
gave adults in 1913, at Saint Paul, from June 11 to July 5. Nearly all
of these appeared between June 17 and July 1, with the maximum
emergence on June 21.

In November, 1912, clover heads were collected at Duluth, St.
Cloud, Winona and Mankato. Adults emerged in 1913 as follows:

Duluth specimens, June 9 to July 1, maximum emergence, June 18.
St. Cloud specimens, June 12 to July 1, maximum emergence, June 18.
y J

100 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

Winona specimens, June 12 to July 5, maximum emergence, June 16.
Mankato specimens, a few on June 17, no others emerging.

Second generation adults from Lewiston, Winona County, began
to emerge July 2, 1913, and reached their maximum July 10. None
emerged after July 23.

A lot of heads collected at Monticello, Wright County, July 24,
1913, gave adults from August 9 to 25, about two thirds of these
emerging from the 14th to the 16th.

In 1914, at Saint Paul, adults were first found in the field June 2.
The time of most abundant emergence of this first generation was June
10. Second generation adults were on the wing June 29. Emergence
continued in varying abundance until October 2. Three periods of con-
siderable abundance were noted, about June 10 as before stated, then
the last week of July and again the first week of September.

Our earliest seasonal record of emergence is May 25. This was
from a lot of clover heads taken at Lewiston, Winona County, Sep-
tember 19, 1913. From these 2,716 adults emerged between May 25
and July 21, 1914. The majority came out early in June. Maximum
emergence between June 6 and 9, 809 adults.

In connection with these data it should be noted that T. D. Urbahns
while working at this station reported the following: “Seeds collected
in October of 1909 and kept in a cold room all winter produced adults
of the seed chalcid all through June of 1910. In the season of 1910 adults
appeared in the field with the first clover blossoms about June 1. They
increased rapidly until about June 15, after which a rapid falling off
in their numbers took place. About June 20 to June 30 adults of this
species could hardly be found. With the beginning of July they began
to increase in numbers and by August 10 they had reached their
maximum abundance for the year. Late in August the adults of this
species rapidly disappeared with the drying of clover blossoms in our
dry season.”

To summarize: Adults of the spring generation appear early in
June, sometimes late in May. They reach their maximum abundance
from about June 9 to June 18. Most of these are out in June but a few
may not emerge until as late as the third week in July. Adults of
the succeeding generation may be found from early in July until
October. The largest numbers are found from about August 10 to 15
and again in the first week in September.

THE CLoveR SEED CHALCID 101

DISTRIBUTION

The clover seed chalcid appears to be widely distributed over the
United States, altho southern records are few. In Minnesota it is
recorded from Duluth, Hinckley, Meadow Lands, Detroit, Bemidji,
Audubon, Fergus Falls, Wadena, Verndale, St. Cloud, Park Rapids,
Itasca Park, Monticello, Windom, Worthington, Owatonna, Winona,
Montgomery, Mankato, Chatfield, Lewiston, Stewartville and in and
around Saint Paul and Minneapolis. As to foreign distribution, we
quote from Urbahns (1914) “Injury from this insect has been ob-
served in cultivated alfalfa seed imported from Germany, Turkestan
and Chile, and in both the cultivated and uncultivated varieties of
alfalfa seed from Turkey and Siberia.”

Foop PLANTS

As before stated, when it was discovered the species were reared
from heads of red clover, Trifolium pratense L., altho at the time its
true relation to the plant was not recognized. In the eastern part of
the United States and in this section red clover seems to be the favorite
food plant. The mammoth variety is infested as well as the medium.
Crimson clover, Trifolium incarnatum L., also is subject to attack and
it is interesting to note that it was from seeds of this plant that speci-
mens were reared by Hopkins (1898) when he discovered the real feed-
ing habits of the species.

While it received the name it bears because it was first observed
infesting the seeds of red clover, more recently it has become an even
worse pest of alfalfa seed in the region where this crop is grown to a
large extent. Bur clover, Medicago hispida Gaertn., is another food
plant.

Apparently the chalcid does not attack white clover, alsike, and
sweet clover. This statement is based on the fact that we have often
looked for it on these plants and have never found it, and have always
got negative results when attempting to breed the species in cages
containing seeds of white clover, alsike and sweet clover.

On July 30, 1912, observations were made on a female chalcid
confined in a shell vial containing a head of red clover in full bloom.
It crawled over many of the florets, touching each repeatedly with its
antennae. It thrust its ovipositor into several of them, usually into the
side through the calyx tube. When it could not do this on account of
the crowded condition of the florets, it would stand on the top, inserting
its ovipositor into the mouth of the corolla. The red clover head was
removed and the insect was tried with sweet clover and then with

102 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

white clover, but it gave no attention to either. Then it was given
the red clover again with the same results as before. Altho no egg
was found when the red clover seeds were dissected immediately
afterward, the behavior of the insect may be considered as strongly
supporting the other evidence that the chalcid does not oviposit in the
seeds of sweet clover or white clover.

NATURE AND EXTENT OF INJURY

The damage is done by the larva inside the seed devouring its con-
tents. In most cases this work is so thoroly done that nothing is left
but the seed coat. An affected seed still containing the insect can
usually be distinguished from a healthy seed by its dull brown color,
lack of luster and slightly shriveled or otherwise misshapen condition.
Moreover an infested seed can be crushed in the fingers while a sound
seed is hard. A seed from which the insect has emerged is an empty
shell with a hole in one side through which the adult made its escape. If
the adult emerges before the seed has been hulled or shattered out of
its receptacle, a hole may also be made in the latter. In the case of
emergence from a clover seed a hole will frequently be made through
the side of the corolla. An adult coming from an alfalfa seed will
make a hole in the pod directly over that in the seed. The plant itself
is apparently not injured and the only way to detect the presence of the
larva is by examination of the seed.

While the damage to the seed crop by the depredation of this pest
has been very great, in many cases the growers have either not suspected
their loss or, when they have, being ignorant of the real cause have at-
tributed the shortage in yield to weather or soil conditions or to the
work of the midge. Empty seed coats from which the adults have
emerged are blown out with the chaff from the huller and thus escape
notice. Many of the seeds containing larvae, being as heavy as normal
seeds, may go into the bins with the latter, so that if the owner does
not recognize them, as many do not, he will overestimate the value of
the yield.

Counts made of infested seeds give some striking results. Fol-
som (1909), writing of conditions in Illinois, states that out of 49
clover seeds taken at random, 14 were found to be injured. Titus
(1904) reports injury to the extent of 40 to 83 per cent with an average
of 50 per cent to the head. Presumably his data were secured near
Washington, D. C. Concerning the extent of injury to the alfalfa seed
crop, Urbahns (1914) says that in samples collected from different
localities, 10 to 30 per cent of the seeds of early crops and 20 to 70

THE CLoveR SEED CHALCID 103

per cent of those of late crops were found to be destroyed by this insect.
He examined several samples showing damage to the extent of 85
percent. Speaking of the money loss, he says that it varies on different
farms from $5 to $60 per acre.

A. W. Morrill states, in the third annual report of the Arizona
Horticultural Commission, that in the Buckeye valley the destruction
of alfalfa seed by the chalcid ranges from 30 to 60 per cent, entailing
an annual loss of $300,000.

According to Swenk (1913), the loss to the alfalfa seed crop in
1911, in Red Willow County, Nebraska, was 80 per cent.

T. D. Urbahns while employed at the Minnesota station examined
many samples of red clover seeds to determine the amount of infesta-
tion. One record which we select from his notes relates to a lot of
2,183 seeds collected in the field during the summer of 1910. Of these,
856 seeds were infested, or 39.2 per cent. Quoting from his notes:
“Estimating the average crop of clover seed under the present (1910)
conditions to be 150 pounds per acre, and this being at a loss of 39 per
cent, the yield in the absence of Bruchophagus funebris would have
been 246 pounds per acre. The seed chalcid is responsible for destroy-
ing 96 pounds per acre.”

The destruction of 96 pounds of clover seed per acre would mean
a money loss to the grower of $18 to $20 per acre at the present
time.

METHODS OF CONTROL

The most common practice where red clover is grown for seed is to
cut the first crop for hay and the second crop for seed. If the first crop
is left standing too long, that is, until the heads are ripe, the eggs
laid in the seeds by the first generation of adult chalcids will have a
chance to develop and produce the adults which lay their eggs in the
seeds of the second crop.

It was first suggested by Webster (1906) and afterwards recom-
mended by Folsom (1909) that the same treatment employed against
the midge be used in combating this insect also. Early cutting of the
first crop would prevent oviposition to a great extent. If any eggs or
young larvae were present, they would die with the drying of the un-
developed seed. Under this treatment the summer generation of
chalcids would be greatly forestalled while the seeds of the second
clover crop would mature early and most of them would be too hard
to receive the eggs of any chalcids that might appear. Clipping back

104 SEVENTEENTH Report STATE ENntomoLocist oF MINNESoTA—1918

the first crop or pasturing it lightly in the spring has been recom-
mended also.

In order to test some of the measures suggested, several field ex-
periments were carried on. In some of these the infestation was so
light that no conclusions can be drawn from the results. Others, more
conclusive, are reported below. The percentage of infestation given
in each case is computed on the basis of 1,000 seeds taken at random
from different parts of the experimental plot.

Mr. Chris Schultz, Simpson, Minnesota, allowed us the use of his
field for co-operative experiments in 1912. Two plots of 2 acres each
were used, having a uniform stand. They were treated as follows:

Plot I.

Clipped back with the mower, May 31.
Cut for seed, September 2.
Infestation, 1/10 per cent. Yield per acre, about 1 bushel.

Mr. Schultz reported that the seed in this plot was brighter and healthier in
appearance than the seed trom Plot IT.

Plot all:

Cut for hay, June 25. Heads fresh in bloom and_ pink.

Cut for seed, September 25.

Infestation, 2 per cent. Yield per acre, about 1 bushel.

Another plot was to have been used for late cutting of the hay but it was cut
early by mistake.

In 1912 also co-operative experiments were conducted on the
field of Mr. Joseph Jackson, Verndale, Minnesota. Four 4-acre plots
of uniform stand were treated as follows:

Riotel:

Cut for hay, June 14. Heads pink and green.
Cut for seed, October 4.
Infestation, 1/5 per cent.

Plot IT.
Cut for hay, June 22. Heads all pink.
Cut for seed, October 4.
Infestation, none.

PloteLil:

Cut for hay, June 26. About half of ‘heads turning brown.
Cut for seed, October 5.
Infestation, 5 per cent.

PlotlV:
Cut for hay, July 26. Heads all brown.
Cut. for seed, October 5.
Infestation, 831/83 per cent.

Tue CLover SEED CHALCID 105

Owing to the inability of the owner to get a clover huller, a
threshing machine was used and this did such poor work that it is im-
possible to give an accurate report of the yield.

In 1913 P. C. Daley, Lewiston, Minnesota, allowed the use of his
field for co-operative experiment. Three plots of one acre each were
selected, these having a uniform stand. They were treated as follows:

Pilot:

Clipped back, June 1.

Clipped again, July 1.

Cut for seed, October 1.

Infestation, 16.7 per cent. Yield per acre, 87 pounds.

Plot IT.

Cut for hay, July 15. Heads all ripe.
Cut for seed, October 1.
Infestation, 31.7 per cent. Yield per acre, 38 pounds.

Plot ll

Cut for hay, July 3. Most of heads turning brown.
Cut for seed, October 1.
Infestation, 17 per cent. Yield per acre, 54 pounds.

In 1914 red clover was available for experimental purposes at
University Farm, Saint Paul. Two plots were used, No. I being on
series 6, Field E, and No. II on series 7, Field E. Each plot was 130x
132 feet. They were treated as follows:

Plotel:

Cut for hay, June 17. Heads pink.

Not cut for seed because of severe infection of clover rust, Uromyces trifolii.

Ripe heads collected October 23 and seeds examined for larvae of clover seed
chaleid.

Infestation, 2 per cent.

Plot II.

Cut for hay, July 17. Heads all brown.
Not cut for seed because of clover rust.

|

Ripe heads collected October 23 and seeds examined.
Infestation, 8S per cent.

It is evident from these results that early cutting of the first crop
reduces the amount of infestation in the second crop sufficiently to
make it a valuable preventive measure.

Attention must be given also to first-year red clover in the seeds
of which the chalcid may breed and be carried over the winter to infest
the crop of the second year. Clipping off the heads or pasturing can
be recommended in this case. Volunteer clover, being almost always
infested by the chalcid, should be kept down as much as possible.

i06 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

PARASITES

Three species of parasitic chalcids have been found attacking
Bruchophagus -funebris. One of these, Tetrastichus bruchophagi
Ashm. is described to considerable length by Urbahns (1917) but it has
not been observed by the writer. The other two species have been
found in our study of Bruchophagus, (1) Habrocytus medicaginis
Gahan. We quote Gahan’s description of the adult.

Fig. 22. Female of H. midicaginis.

Female—Length about 1.7 mm. Head and thorax closely punctate,
the punctures on the medial portion of the mesoscutum slightly larger
than those on the scapulae and scutellum; antennae with two ring-
joints; pedicel and first funicle joint, excluding the ring-joints, about
equal; following funicle joints a little longer than the first and a trifle

THe CiLover SEED CHALCID 107

longer than broad; viewed from in front the head is broader than
long, the clypeal region with converging striae and a deep median sinus
on the anterior margin; viewed from above, the head is slightly broader
than the thorax, narrow anteroposteriorly, the occiput slightly concave,
the ocellocular line longer than the lateral ocellar line, the lateral ocellar
line not equal to half the postocellar line; pronotum strongly transverse
with a sharp margin anteriorly ; propodeum short, without a neck, with
a median carina and lateral folds, the region between the lateral folds

Fig. 23. Male of I. longfellowzi.

more or less distinctly wrinkled and with a fovea-like depression at the
base and another at the apex of the fold; the region outside the lateral
folds is usually more faintly sculptured with indistinct lines ; propodeal
spiracles elliptical; marginal and post-marginal veins subequal, the
stigmal one-third shorter; abdomen conic-ovate, about as long as the
head and thorax and nearly smooth, the dorsal segments beyond the

108 SEVENTEENTH Report STATE ENtToMoLociIst oF MINNESoTA—1918

first with very faint transverse lines. Head and thorax aeneous; an-
tennae brown, the scope slightly paler beneath; wings hyaline; all coxae
aeneous like the thorax, all trochanters and femorae black with an
aeneous tinge ; tibiae and tarsi usually reddish yellow, the former often
brownish except at apex; apical joint of all tarsi dark; abdomen
polished aeneous.

Male—unknown.

(2) Idiomacromerus longfellowi Girault. This species was dis-
covered in the larval stage in a seed of red clover where it had eaten a
larva of B. funebris, leaving only the empty skin mandibles. It was
reared to the adult. After a number had been reared and collected
in the field several specimens were submitted to Mr. A. A. Girault
(1917) who described the species as new. His description of the adult
is as follows:

“7 mm., with ovipositor two thirds longer. Like genotype but
hind femora simple, compressed, head somewhat longer, longer than
wide, antennae at eye ends, thus lower. Green, wings with an oblique,
twice longer than wide, stain, caudo-proximad from apex of stigmal.
First tibiae save near base, straw; knees, tipe of tibiae and tarsi 1-3,
white. Eyes nearly naked. Body densely, very finely scale punctate.
Propodeum plane, not long, with foveae at cephalic margin between
spiracles. Pedicel twice longer than wide at apex, ring joint 2 wider,
shorter than 1, a third the length of funicle 1 which is nearly twice
wider than long, others a little longer. Mandibles tridentate, teeth
subacute, not large. Stigmal with slender ’
neck. Venation as in genotype. Male
same, nearly.”

Larva. Grublike, nearly white, moder-
ately pubescent, 1.5 mm. long. All body
segments distinct. Dorsum of abdomen
with segmental folds. Head with two con-
spicuous brown tubercles. Mandibles brown,
acute, not dentate. After expulsion of in-
testinal contents, preparatory to pupation,
the body becomes a clearer white and more ... :

= Wig. 24. Larvae of I. long-
flat in form. fellowi.

Pupa. At first yellow, the abdomen being paler than the head and

thorax. Sclerital sutures brown. It gradually becomes darker, and
just before changing to the adult, it is black with green reflections.
Eyes reddish brown. The pupal period of a specimen observed during
May was thirteen days.

THE CLover SEED CHALCID 109

Efficiency of the Parasites. The following figures are taken from
our notes. A lot of alfalfa pods collected when ripe gave in the insec-
tary 151 adults of B. funebris and 165 of H. medicaginis which means
that over 52 per cent of the Bruchophagus larvae were destroyed. I.
longfellowi did not appear in this
lot, altho we have found it in alfalfa
at other times but never so numer-
ous as the other species. In a lot
of red clover seeds, which gave in
the breeding cage 1,216 adults of
B. funebris and 176 parasites, the
latter comprised 156 of J. longfel-
lowi and 20 H. medicaginis. In an-
other lot of red clover seeds there
emerged 937 B. funebris, 86 I. long-

Fig. 25. a. ees of male I. longfellowi. fellow and I4 HT. medicaginis.

b. Pupa of female I. longfellowi. From a lot of alfalfa pods we
reared 151 adults of B. funebris and 165 adults of Habrocytus medt-
caginis. If we assume that each parasite emerging represents one
Bruchophagus larva destroyed, then the original number of Brucho-
phagus larvae was 316, of which over 52 per cent had been killed by

the parasite.
SUMMARY

The clover seed chalcid, at first thought to be parasitic on weevils
infesting seeds, is now recognized as one of the worst pests of clover
and alfalfa seed.

The adult is a small, black, wasp-like four-winged fly easily mis-
taken for a gnat by one not familiar with it. The egg, which is in-
visible to the naked eye, is deposited in the soft green seed of clover
or alfalfa. The larva hatching from it is white and maggot-like, fill-
ing the empty shell of the seed when it is full grown. The pupal stage
is of short duration. The adult in emerging gnaws a hole through the
seed shell and escapes. At least two generations appear during the year.
The species hibernates in the larval stage inside the seed.

The clover seed chalcid is found throughout most of the United
States. In Minnesota, it appears to be present wherever clover is grown.
It is found also in Germany, Turkestan, Chile, Turkey and Siberia.

The first adults appear in June. They are most abundant about
the middle of August and are numerous again in the early part of
September. A few may be found until October.

110 SEVENTEENTH Report STATE ENtToMoLoGist oF MinNEsSoTA—1918

The food plants are red clover, mammoth and medium, crimson
clover, bur clover, and alfalfa. Alsike, white clover and sweet clover
are apparently immune.

The injury is caused by the larvae devouring the contents of the
seed. The greatest amount of damage to clover seed recorded in Minne-
sota is 39 per cent. In other sections of the country, especially where
alfalfa is grown, the injury is often much worse, 85 per cent being
recorded in one instance.

As a preventive measure, the first crop of medium red clover
should be clipped or cut early for hay to prevent the first generation of
seed chalcids from depositing their eggs. Neighborhood co-operation
in this should be urged. First year clover should be kept from bloom-
ing and volunteer clover destroyed.

BIBLIOGRAPHY

Bruchophagus funebris Howard

1899—Pettit, R. H— Bull. No. 175, Mich. Agr. Exp. Sta., pp. 366, 367.
1904—Titus, E. S. G—Bull. No. 44, U. S. Dept. Agr., Div. Ent. pp. 77-80.
1906—W ebster, F. M.—Circ. No. 69, U. S. Dept. Agr., Bur. Ent., pp. 7-9.
1909—Foisom, J. W.—Bull. No. 134, Ill. Agr. Exp. Sta., pp. 125-133.
1911—Morrill, A. W.—Third Ann. Rep. Ariz. Hort. Comm., pp. 27, 28.
1913—Swenk, M. H.—Bull. No. 1, State Ent. of Nebr., pp. 89-94.
1914—Urbahns, T. D.—Farmers Bull. No. 636, U. S. Dept. Agr. pp. 1-10.

Habrocytus medicaginis Gahan
1915—Gahan, A. B.—Proc. U. S. Nat. Mus., Vol. 48 pp. 163, 164.
1916—Urbahns, T. D.—Jour. Agr. Research, Vol. VII, No. 4, pp. 147-153.
[diomacromerus longfellowit Girault

1917—Girault, A. A.—Descriptiones Hymenopterorum Chalcidoidicarum
Variorum cum Observationibus III, p. 8 Hillmead Press, Glenn
Dale, Maryland.

Tetrastichus bruchophagi Gahan

1913—Gahan, A. B.—Proc. U. S. Nat. Mus., Vol. 46, p. 439.
1917—Urbahns, T. D.—Jour. Agr. Research Vol. VIII, No. 7, pp. 277-282.

AY PRELIMINARY REPORT 'ON THE TROMBIDIIDAE, OF
MINNESOTA?

By C. W. Howarp?

In the vicinity of Lake Minnetonka and other lakes near Minne-
apolis and St. Paul, summer visitors are attacked by “chiggers,”
similar to those found in the southern states, altho not so severe in their
effectsonman. They are apparently the larvae of a mite belonging to the
Trombidoidea. Several forms in this group are also of economic im-
portance in being enemies of insect pests. Three years ago a study
of these mites was begun, part of the work centering about an investi-
gation of the life history and biology of the members of the family
Trombidiidae, found in Minnesota. The purpose was to make a com-
plete study of this family before publication. As it will be impossible
for the writer to complete this study, and as our information about the
representatives of the family in America is very incomplete and frag-
mentary, the following descriptions and notes are presented at this
time. Several apparently new species have been found in the state
and these are also described.

Those wishing more general information on the superfamily are re-
ferred to Report 108, U. S. Dept of Agr., Office of the Secretary, by Nathan
Banks, and to Redia, Vol. 8, No. 1, containing an account by Berlese of the
trombidium mites of the world, but excluding North American forms almost
entirely.

KEY TO ADULTS AND NYMPHS FOUND IN MINNESOTA

A. Palpi with a single claw.
B. Dorsal grove expanded at the middle of its length.
(Cc: A pulvillus between the tarsal claws; eyes truncate, a large
species. Allothrombium pulvinus
CC. No pulvillus, eyes sharp pointed, a small species; a white
band across abdomen. Trombidium maculatum
BB. Dorsal groove expanded at the anterior end. Abdomen deeply
indented on the posterior margin. Sericothrombium scabrum
AA. Palpi with two claws.
183, A chitinous plate on the posterior part of the dorsum.

Eutrombidium locustarum

1 Published with the approval of the Director as Paper No. 140 of the Journal
series of the Minnesota Agricultural Experiment Station.

2In fairness to Mr. Howard, who has been in China since October, 1917, it should
be stated that this paper has not been edited, corrected or revised by him.—A. G. R.

111

112 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESoTA—1918

BB. No chitinous plates on the abdomen.
(C. Tarsi I very much swollen, a very small species.
Microtrombidium magnitarse

CC. Tarsi I not so large; larger species.

ID): White markings on the abdomen, eyes sessile, body
hairs very slender. Microtrombidium albovittatum
DD. No white markings on abdomen, body hairs not so
slender.
E. Body hairs spindle shaped, grooves on dorsum

form an inverted triangle.
Microtrombidium triangulum
EE. Body hairs stout, with expanded tips or globose;
no constriction of abdomen.

Ee Hairs of body globose mixed with stout
hairs whose expanded tips are turned
backward.

Microtrombidium nopal-rubrum
FF. Hairs stout and thick, or with expanded
tips turned backward; six pairs of large

pits on the dorsum.
Microtrombidium punctatum

KEY TO) WARVAE

IX Palpi with two claws, one simple and one bifurcate.
B. Larger claw deeply bifurcate; spines on coxae slender and barbed;
processes on mandibular sheath clavate with numerous spines on
the tip. Allothrombium pulvinus

BB. Larger claw not so deeply bifurcate, spines on coxae short and
bifurcate ; processes on mandibular sheath clavate.
Eutrombidium locustarum

AA. Palpi with one bifurcate claw.

B. Claws on third tarsi of equal length; processes on mandibular
sheath blade-like or palmate.
(CG Anterior dorsal shield long and narrow, lateral edges curled

under posterior dorsal shield quadrate in outline; processes
on mandibular sheath blade-like.

Microtrombidium triangulum
CC. Anterior dorsal shield as wide as long; lateral edges not
curled under; posterior dorsal shield spindle-shaped ; processes
on mandibular sheath palmate.
Microtrombidium muscarum (?)
BB. Claws on third tarsi not of equal length, the shorter one extends

dorsad; processes on mandibular sheath brush-like.
Sericothrombium scabrum

Allothrombium pulvinus Ewing.
All. pulvinus Ewing (in manuscript)

Adult females: Color: dull scarlet, darker than Eu. locustarum,
more nearly approaching Brazil red in tone, a small triangular area at

TROMBIDIIDAE OF MINNESOTA 113

the base of the cephalothorax on the dorsum and posterior to the
genital opening on the ventral side is usually brighter colored. Size:
3.75 to 5 mm long by 2 to 2.5 mm wide. The males are smaller. Body
constricted near the middle, widest anteriorly, covered thickly with
slender plumose hairs. On the dorsum of abdomen three transverse
grooves and a median posterior depression; on the venter two trans-
verse grooves; genital opening posterior to coxae IV, anal opening
nearer to the posterior margin than to the genital opening. Cephalo-
thorax wider than long, the base somewhat concealed by the overhang-
ing abdomen. Dorsal groove expanded a little posterior of the middle.
Eyes on long pedicels located a little further anterior than the expan-
sion of the dorsal groove. Palpi with segment II nearly three times
as long as segment I and considerably swollen, segment III about a third
of segment II in length, 1V twice as long as III, with a single stout claw
at its tip. The thumb is as long as or longer than segment IV, a little
clavate in outline. Mandibles long and slender.

The legs are long and slender. Between the claws at the tip of
the tarsi is a hairy pulvillus. Tarsus of leg I not swollen. The male
differs from the female in its smaller size, more pronounced dorsal and
ventral grooves, and shorter and wider genital opening.

Nymph. Similar to the adults except in the following points:
body smaller in proportion to the length of the legs, covering of hairs
more sparse, cephalothorax and legs yellowish, while the body is dark
orange colored, cephalothorax larger in proportion to the size of the
body, and tarsi I slightly swollen. Size unengorged, 0.45 x 0.35 mm,
engorged 0.80 x 0.60 mm.

Larva. Unengorged: color scarlet, size 0.30 mm long by 0.20 mm
wide. Elliptical in outline, widest near the middle, ends broadly
rounded. On the dorsal side an anterior chitinous plate or shield
nearly a third of the length of the body and irregularly pentagonal
in outline. Near the lower central portion a pair of very large pits
from each of which arises a long slender barbed hair, three other
pairs of stout barbed hairs near the margins. The paired eyes just
laterad of posterior angles of this shield. A smaller elliptical plate
just posterior to and contiguous to the anterior plate. Numerous
heavy barbed spines on the abdomen. Ventral side with spines similar
to the dorsum. Coxae very large, I and II contiguous, III separated
slightly from II. Opening to tracheal system between I and II. The
mouth parts are hidden beneath the dorsal shield. Palpi short and swol-
len, segment IV with a heavy bifurcate terminal claw and a smaller
simple post-terminal claw. Thumb papilla-like with two very long

114 SEVENTEENTH Report STATE ENntTomMoLocist or MINNEsSoTA—1918

plumed hairs on the tip, besides several small hairs. Mandibles re-
tracted into a surrounding sheath. On the base of this sheath is a
pair of large clavate spines, brush-like at the extremity. Legs slender,
tarsi all normal, with two stout curved claws and a dorsal tactile hair.
When engorged the larva becomes 0.8 mm long by 0.5 mm wide.
Coxae II and III become widely separated as well as the posterior
dorsal plate from the anterior dorsal plate.

Eggs. Spherical 0.19 to 0.20 mm in diameter; outer shell smooth ;
color scarlet.

Adults collected at many points in Hennepin, Carver, Ramsey, and
Washington counties, Minnesota, probably found in all parts of the
state where conditions are suitable.

This species was named for me by Ewing as Allothrombium
pulvinus, with the statement that his description was still in manuscript.
It is extremely common in certain regions of Minnesota. What is
probably the same species is mentioned by Riley and Johannsen (1914)
as occurring about Ithaca, N. Y. It is the largest of our Minnesota
species. The color is a dull scarlet, as if they had traveled over dry
dusty soil and marred the original brightness of their velvety scarlet
coats. On rocky or gravelly river banks where there is a great deal
of undergrowth and where the soil is covered with fallen leaves they
are especially common. They are seldom found close to the water’s
edge, but usually high up where the soil is dry. They are also found
along the edges of woodlands where the growth is scrubby and even
along the edges of cultivated fields. During the last spring, however,
quite a few were taken in a low, wet, marshy flat along the banks of
the Minnesota River in company with Sericothrombium scabrum, Eu-
trombidium locustarum, and Microtrombidium magnitarse. Because
of its abundance fairly complete observations were made on this
species.

Adults appear in late summer and autumn, i. e., from late August
to late October. During this time they are active during mid-day hiding
in the soil and leaves at night time until a heavy frost appears, after
which they bury themselves in the soil in a cell two or more inches be-
low the surface. There they spend the winter until the frost is out
of the ground and small forms of animal life become active. By
April 1 they once more become active and may be seen on the search
for food or preening themselves in warm spots of sunshine. In doing
this the legs and palpi re curled beneath the body, the mandibles and
palpi are rubbed with the front tarsi, then the legs are brushed and
cleaned with any tarsus which is convenient. In searching for food

TROMBIDIIDAE OF MINNESOTA ; 115

the palpi and first pair of legs are held forward and act as feelers.
As soon as a victim is touched it is grasped by the palpal claws and
held as if in a hand between the claws and thumbs. The sword-like
mandibles are thrust into the body, moved about by a more or less
circular motion, and the body fluids sucked out. The mandibles may be
removed several times and thrust in at a new location. From April
1 to the middle of June they continue their search for food. If
sufficient food is at hand four to six days will suffice for full engorge-
ment. The food consists of small insects and insect-like forms in the
soil or on low plants. In the field we have seen them feeding on small
coleoptera larvae, small adult chironomids which had fallen to the
ground, small spiders and plant lice. In the laboratory they have
fed on killed coleoptera larvae, injured centipedes, very small ant larvae,
aphids

5)

young grasshopper nymphs just emerging from the ‘amnion,’
and their eggs, eggs of Sericothrombium scabrum, and upon members
of their own species. It seemed to be more often the larger females
which devoured the smaller males when there was a lack of natural
food in the breeding jars. In the field the shrivelled remains of mites
may often be found in such places as to arouse the suspicion that
cannabalism may be fairly common. They seem to be extremely fond
of plant lice and are often seen climbing plants and shrubs in search of
them, going as high as two or three feet. This is the only one of our
trombidiums which is commonly seen climbing plants. It is also able
to walk up the sides of a glass jar. The presence of the pulvillus will
explain this ability to climb. In the laboratory we have fed adults
on the winter eggs of willow aphids and upon the aphids of box elder,
salvia, aster, dahlia, sunflower, red clover, cherry, woolly aphis of the
elm and upon white-fly larvae. They will also devour grasshopper eggs
readily, but probably do not do so in nature, as they do not seem to
show any tendency to burrow in their search for food. On the other
hand while animal food seems to be their choice they will take other
forms of food. On one occasion we found a specimen enjoying a
meal from a crumb of moist bread which a picknicker had dropped on
the ground. Repeatedly we have found them evidently sucking nectar
from fallen oak catkins, and liquid from the sticky bud coverings
of box elder, as well as sucking moisture from wet soil. One lot of
several adults was brought into the laboratory and placed in a jar
with very moist soil. No food was given. They were unengorged and
several were noticed inserting the mandibles into clumps of moist soil
exactly as if feeding on an insect. Next morning they were very
noticeably increased in size. After a few days eggs were deposited.

116 SEVENTEENTH Report STATE ENtomoLocist oF MinNnEesota—1918

This was repeated a second time and engorgement secured and eggs
iaid when soil moisture was the only food obtainable.

The periods of the life history are very irregular owing to the
difficulty which some individuals meet in finding a sufficient food sup-
ply. As soon as the female has become engorged with food she pre-
pares for oviposition. The larger number oviposit between April 22
and June 25. The mating process has not been observed except that in
a breeding cage on one occasion in early April several pairs were
engaged in what seemed a mild acrobatic contest. Altho the cage was
watched closely no actual mating was seen.

The eggs may be placed at the surface under leaves or other de-
tritus, or beneath the surface at a depth of three-eighths to one-half
inch. The eggs are cemented together rather firmly and the mass
further bound together by a few silvery silken threads. Each mass
may contain from two hundred to four hundred eggs, depending upon
the extent to which the female has been able to secure food before
oviposition. The incubation period of the eggs is from three to five
weeks, depending upon the temperature. At about the middle of the
period of incubation the outer shell of the egg splits open and the
legs of the embryo covered with the inner membrane protrude in a
conical fashion above the ruptured edges of the egg shell. At this time
the mass of eggs assumes a paler color. Hatching of the larvae occurs
from late May to mid July.

Soon after hatching the six-legged larva crawls about upon the soil
and up onto the vegetation, always going upward in search of some
insect to which it may attach. Apparently plant lice are their favorite
host. Several tried to engorge on adult Arphia pseudonietana and
Chortophaga viridifasciata, but were unable to do so. They refused
to feed on small beetle and ant larvae. The soft bodied aphid is more
easily punctured by their small mandibles. They were reared on aphids
from red clover, lettuce, box-elder, snowball and raspberry. As many
as five or six may attach to one aphid, and in two to four days will
swell to many times their original size. If disturbed or for any other
reason dissatisfied they will detach themselves and roam about until
they find another suitable aphid to which they will attach and feed.
When, however, they are nearing engorgement removal from the host
is difficult or impossible.

When fully engorged the larva drops to the soil and burrows one-
eighth of an inch to two inches below the surface, depending on the
character of the soil, and there it goes into a resting condition. This
securs usually during the month of June or early July. While in this

TROMBIDIIDAE OF MINNESOTA ILI

condition the larval skin hardens and the nymph is formed inside.
About one week is spent in the soil after which the nymph appears at
the surface. Nymphs are found from late June to late July. They re-
semble the adult closely except for size, and feed as do the adults on
aphids and other insects. By late July they enter the soil once more or
hide in curled up dried leaves at the surface. The skin hardens and in-
side is formed the adult mite. In about two weeks the adult bursts the
old dried nymph skin and crawls to the surface of the soil. From this
time, early to late August, onward, the adults feed until cold weather
when they enter the soil once more and remain until early spring.

Altho somewhat localized in distribution this species must
be very beneficial, especially in the control of aphids, as every stage
feeds upon them, even destroying the winter eggs. It seems to have
few enemies. Rove beetles in one of the breeding jars were seen to
eat the adults and ants were seen attempting to carry them away. No
other insect has been seen, however, to prey upon them in the field or
in breeding jars, nor have any parasites been reared from them.

The larvae of this species seem to have no relation to the “chigger”’
pest. On several occasions large numbers were placed inside the writ-
ers stocking or underwear, but in no case did one attempt to penetrate
the skin. Where they are most abundant there seems to be little
trouble from “Chiggers.”

Eutromlidium locustarum (Walsh).

Astoma locustarum Walsh, Practical Entomology, Vol. I p. 126;
1886 LeBaron, Ill. Report. 2, p. 61; 1875.

Astoma gryllaria Riley. 7th Missouri Report, p. 176; 1875.

Trombidium locustarum Riley, Rpt. U. S. Ent. Comm. p. 306;
1878.

Ottonia locustarum Banks, Trans. Am. Ent. Soc.: Vol. 21, p. 213;
1894.

Microtrombidium locustarum Ewing. System. and Biol. Study of
Acarina of Ill. Univ. Studies, Univ. Ill. Vol. 3, p. 94; 1909.

Adult female. Color, scarlet, darkening with age, in certain lights
the folds on the abdomen have a whitish reflection, under side brighter
than dorsal. Size, 2.75 to 3 mm. long by 2 mm. wide. When en-
gorged may reach a length of 4 mm. long by 2.50 mm. wide. Body
covered with slender plumose hairs; constricted near the middle, wider
in anterior half, a deep transverse groove at the line of constriction, a
second near the middle of the wide anterior half; a large trapezoidal
chitinous plate at the posterior end of the dorsum, nearly a third as
iong as the abdomen, and a little longer than wide; a shallow arched

118 SEVENTEENTH Report State Entomotocist or Mrnnesota—1918

transverse groove anterior to the plate. On the ventral surface a deep
transverse groove between the two anterior and the two posterior coxae
and another just posterior to coxae 1V, a longitudinal groove extend-
ing from this to the posterior end of the body. Genital opening op-
posite coxae IV. Anus less than half way between the genital opening
and the posterior margin. .

The cephalothorax inserted in a deep anterior emargination of the
abdomen, wider than long, base somewhat hidden by the overhanging
abdomen. Eyes sessile, two on each side, placed at about the middle
of the length of the cephalothorax. Dorsal groove expanded at the
middle of its length into a quadrate area bearing two stout spines.
Palpi with segment II a little more than three times as long as seg-
ment I, segment III one-third as long as segment II, segment IV with
two stout terminal claws, the smaller on the inner side. The inner sur-
face of segment IV has a variable number of heavy spines, usually
seven in a double oblique row; the oblique rows of spines are sometimes
reduced to two in each row, and there may at times be few to several
spines forming a dorsal crest on the segment, the number not always
corresponding on the two palpi of a single specimen. The outer sur-
face bears three very heavy nearly equal spines, near the ventral
edge; in some specimens there may be only two, in others four; these
may also vary on the two palpi of a single specimen; in ten specimens
examined the number were as follows: 2-2, 4-4, 3-4, 3-2, 4-2, 3-3, 2-3,
2-2, 3-3, 4-3. Thumb longer than segment IV, of nearly equal diameter
throughout length, four times as long as wide.

Legs slender; tarsi I nearly three times as long as wide.

Male. Similar to female except as follows: smaller, 2 to 2.50 mm
long by 1 mm wide, constriction of body and grooves more marked,
does not engorge so fully as the female, cephalothorax more exposed,
dorsal plate only twice as long as wide, and more angular, abdomen
narrower posteriorly, genital opening narrower, legs relatively longer
than in female.

Nymph. Resembles the adult closely. Size 1.50 to 2 mm long by
0.75 to 1 mm wide. Hairs on dorsum sparse and of a paler scarlet,
those on venter, legs, and cephalothorax cream colored. Body more
pointed at posterior extremity. Cephalothorax resembles that of the
adult, except that it is a little larger in proportion to the size of the
body. Palpi has only two heavy spines present on the outer surface
of segment IV while the inner surface has an oblique row of six heavy
curved spines whose tips reach beyond the base of the terminal claw,
and also a dorsal comb of five heavy hairs. The legs are slender,

TROMBIDIIDAE OF MINNESOTA 119

longer in proportion to the size of the body than in the adult, tarsi I
slender, two and one-half times as long as broad.

Larva, unengorged. Color, scarlet, size 0.20 mm long by 0.11 mm
wide, oval in outline, wider in front. On the anterior end of the dor-
sal side is a large, more or less pentagonal chitinous shield, which
completely hides the mouth parts beneath, and is more than a third as
long as the body. Four pairs of spines are present on this shield,
one of extreme length at each posterior angle. Posterior to it is a stout,
wide, quadrilateral shield, also bearing four pairs of plumose hairs.
Laterad of each posterior angle of the anterior shield is a pair of eyes.
Abdomen with several plumose hairs—Ventral side, with the coxae
large and contiguous. Opening of tracheal system between coxae |
and IJ. Each coxa has a short stout bifid spine near the insertion of
the legs. Mandibles sabre-like projecting from a tubular sheath be-
neath the dorsal shield, a pair of heavy clavate appendages on the
ventral side of this sheath. Palpi short, segment IV with two claws,
the terminal one larger and bifid. Thumb short and bears several
stout hairs on its tip. Abdomen with stout plumose hairs. Legs stout,
tarsi slender, claws long and slender, a tactile hair arising between
the claws and extending dorsad of them. Tarsus III with one very
long curved claw, the second claw short and thick and raised dorsally,
ventrad below the long claw projects a stout heavily plumed pul-
villus-like tactile hair.

Larva, engorged. Reaches a size of 1.22 to 1.30 mm long by 0.53
to 0.60 mm wide, losing all resemblance to its previous form. Body
widely rounded at both ends, and somewhat constricted at the middle.
Integument with fine transverse striations—Coxae I and II remain in
contact, but tarsus III becomes separated with the expansion of the
body as do also the two dorsal shields.

Eggs. Spherical, outer shell smooth and shining, color flame
scarlet, 0.16 mm in diameter.

Adults taken at many points in Hennepin, Ramsey, and Otter-
tail counties, Minnesota. It is apparently present throughout all the
grasshopper areas of the state.

The adults of this mite are found on or in the soil in open ground
during the early spring, the first warm days bringing them out of their
winter hiding places. They start immediately in search of grasshopper
egg pods. Riley records that in locust breeding grounds they may be
so abundant as to give the soil a scarlet appearance. In grasshopper
areas in Minnesota they may be so numerous in ordinary years that
several hundred can be collected in three or four hours. During locust

120 SEVENTEENTH REporRT STATE ENToMoLoGIstT oF MInNNESoTA—1918

cycles they become more noticeable. Apparently the character of the
soil does not influence their distribution for they may be found on dry
sandy hillsides and in low wet bottom lands, providing grasshopper eggs
of one species or another are present. Every nook and crack in the
soil is searched by the adults in their efforts to find grasshopper egg
pods. When one is found they at once begin to dig down into it,
doubtless aided materially by the heavy spines on the anterior edges of
the palpi. Sometimes four or more may be found in one egg pod,
but usually only one. The egg shells are pierced by the sharp blades of
the mandibles and the contents sucked out until the shell collapses.
How many eggs are necessary before the adult is fully engorged and
ready for oviposition is not known exactly. Apparently three to four
are sufficient. We have found this mite in the egg pods of Melanoplus
bivittatus, Melanoplus femur-rubrum, Melanoplus atlanis, Melanoplus
minor, and Stenobothris curtipennis. Probably the egg of any acridid
will be eaten. It is possible that adults may subsist in part on moisture
in soil. In cages we have secured partial engorgement and oviposition
when the only food present was moisture in a soil rich with humus.
While the female is entering the egg pod the males seem to be attracted
to her, as many as three or four may be found attempting to enter the
same burrow after the female. Actual mating of the sexes has not
been observed. The female engorges to twice its previous size and be-
comes so swollen that the typical grooves on the body nearly disap-
pear. The male does not engorge to such an extent. As soon as the
female is full fed she excavates a smooth walled chamber not far from
the egg pod where she fed and deposits her eggs after an interval of
nine to twelve days. These chambers are half an inch to an inch below
the surface of the soil. The eggs are bright orange color and very
conspicuous against the dark soil. They can usually be found from late
May to early June. Various masses of eggs in our breeding cages con-
tained from three hundred to seven hundred eggs; their delicacy and
the tenacity with which they are glued together makes accurate count-
ing difficult. An average of four hundred to five hundred eggs is prob-
ably correct. In twenty-four to thirty days the eggs hatch. Previous
to hatching, when the embryos are twelve to fourteen days old, the outer
shell of the egg splits and the legs of the embryo project upward in a
more or less conical manner thru the rent in the shell, still enclosed by
the inner membrane. As soon as hatched the six-legged larvae crawl
about rapidly in search of grasshoppers to which they may attach.
Larvae which have just crawled upon grasshopper nymphs or adults
may be found from late June to mid July, altho a few will be met with

TROMBIDIIDAE OF MINNESOTA 121

even as late as early October. This unevenness in the life history
is due to the delay which often occurs in the adult finding food in
spring. The larvae attach themselves to any stage of the grasshopper
from the first instar to the adult. They prefer to attach at a com-
missure between the segments of the abdomen or thorax, especially
under or on the wing pads, or at the joints of the tarsi or about the
mouth. On adults they often attach on the veins of the wings. The
reasons for attaching at such points are obvious, when their delicate
mouth parts are considered. Almost any species of acridid may be
chosen as host. We have fed them on Tettix sp., Melanoplus bivittatus,
M. femur-rubrum, M. gladstoni, Stenobothris curtipennis, Orphulella
speciosa and O. palidna. Anywhere from one to one hundred twenty-
four larvae have been counted on a single grasshopper nymph. The
orange colored larvae soon engorge to several times their original size,
losing all resemblance to their previous form and resembling engorged
female ticks in appearance. In fact they are popularly known as grass-
hopper ticks. Engorgement may require as long as fourteen days.
If it so happens that a larva has just attached to a nymph which is
about to molt or is unable to penetrate the body wall and reach the
body fluids and so not engorge readily, it will migrate to the moulted
host after the skin is sloughed off, or to a more favorable part of the
body. If, however, it has begun to engorge it is unable to migrate.
Usually engorgement is completed between moults, or after the host
has moulted to the adult stage.

As soon as the larva is fully engorged, which occurs for the ma-
jority by mid July, it drops off and enters the soil, burrowing from one
quarter of an inch to one inch deep. The hardened larval skin acts as a
cover for the developing nymph, which emerges in about five days. The
nymph appears in late July to mid August when many grasshoppers are
beginning to oviposit, and it at once searches for these eggs as food,
altho at this time they may take other food than grasshopper eggs. We
have had some partly engorge on angle worms and attempt to feed on
larvae of M. domestica. The latter, however, proved too active. They
will readily attack eggs removed from the oviducts of female grass-
hoppers. After engorgement, which requires fourteen to twenty days,
they again enter the soil and pass through a transformation stage from
which the adult emerges. The adult may eat at this time or it may go at
once into hibernation. Most of those in our breeding cages refused to
eat. The mature adults appear during late August when many grass-
hoppers are ovipositing.

The economic importance of Eutrombidium locustarum is un-

122 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESoTA—1918

doubtedly great. The larvae, even if present in large numbers, prob-
ably do little more than weaken the grasshoppers to which they at-
tach, but the adults and nymphs render a considerable service by
destroying large numbers of grasshopper eggs. While they may not
destroy all the eggs in any egg pod the fact that both nymphs in late
summer and the adults in spring and to some extent in autumn feed on
them, must make the aggregate destroyed quite large and we must con-
sider them as one of the important natural checks on grasshopper in-
crease.

The larvae of this species seem to have no connection with
“Chiggers.” They have twice been placed in large numbers inside
the clothing of the writer but no unpleasant results followed. The
fact that they inhabit open ground would clear them of any connection
with the “Chiggers.”

Microtrombidium magnitarse Ewing.

Micro. magnitarse Ewing. Ill. Univ. Studies Vol 3, p 92; 1909.

Adult female. Color, dull scarlet, size 1.50 mm long by 1 mm
wide. Body oval, only very slightly constricted at the middle, wide-
iy rounded behind, wider in front, anterior edge concave, clothed thick-
ly with short slender plumose hairs, the dorsal surface with a trans-
verse groove just posterior to the forward margin, a second groove
near the middle may be present or absent. Ventral surface with
grooves corresponding to those on dorsum. Genital opening opposite
coxae IV. Anus half way between genital opening and posterior
margin.

Cephalothorax rather elongate, base concealed only in part by the
abdomen. Dorsal groove expanded at the posterior end. Eyes sessile.
Mandibles long and slender. Palpi stout but not much swollen, seg-
ment II nearly twice as long as wide, segment III as wide as long,
segment IV twice as long as III, two long heavy claws at the tip, the
inner one smaller. On the inner side, a crest of three or four heavy
curved spines on the dorsal margin and three irregularly placed spines
at the base of the thumb; thumb short and tapering, about three times
as long as wide.

Legs slender, legs I not as long as the body; legs II and III
three-quarters as long as I : legs IV reach beyond the end of the body.
Tarsi I very much swollen, more than half as wide as long, usually
held so that they are turned backward toward the.body.

Male, smaller than female, 1 mm long by 0.50 mm wide, grooves
more marked.

Adults of this species were collected in decaying leaves and wood

TROMBIDIIDAE OF MINNESOTA WZ

and other vegetable matter in low bottom lands along the Minnesota
River near Minneapolis, also under decaying leaves in woodland about
Lake Minnetonka and near the University Farm Campus in May 1917.
Ewing records this species as collected from under the bark of an
ash tree. In the laboratory we were unable to ascertain anything as
to its habits except that it seems to prefer wet, decaying vegetable
matter as its habitat. It is the smallest of our local trombidiums.

Microtrombidium triangulum, n.sp.

Adult female. Color, dark scarlet, lighter when engorged.
Body elongate oval, broadest in front, narrower behind where it is
broadly rounded, no marked median constriction. Size—1.55 mm
long by 1 mm wide. Dorsal surface with a shallow transverse groove
posterior to the cephalothorax, two other strongly marked transverse
grooves, and at the posterior end three pits in the form of an inverted
triangle, these and the tips of the grooves are connected by longitudinal
grooves. On the ventral side a transverse groove posterior to cephalo-
thorax and another below coxae I and II; genital opening opposite
coxae IV; anus just posterior to genital opening. Surface of body
covered with short, stout, spindle-shaped hairs, each covered with
numerous branches. In the region of the cephalothorax and in the
median portion of the venter these become long and more slender.
The hairs on the legs are slender and branched.

Cephalothorax entirely exposed, wider than long. Eyes sessile,
Dorsal groove with a prominent posterior expansion, Palpi short and
stout, segment II swollen, two thirds as wide as long, segment III, as
wide as long, a third as long as II, segment IV longer than III, two
stout claws, the inner smaller thumb short and thick, pointed at tip, on
the outer surface of segment IV a row of stout bristles forming a crest
on the dorsal margin, seven other bristles arranged in diagonal rows on
the outer face. The inner surface bears one heavy spine at the base of
the thumb.

Legs slender, lighter colored than body, Tarsi I, short and swollen,
a little less than half as wide as long.

Male. Similar to female—length 1 mm long by 0.70 mm wide.

Larva, unengorged. Of a light yellowish orange color. Body
slender, length 0.25 mm by 0.13 mm wide. On the anterior end the
chitinous shield is an elongate pentagon, not quite twice as long as
wide, the two anterior edges are curled in toward the ventral side, a
pair of small spines near the rounded anterior end and another near
each posterior angle, in a large pit. Eyes are triangular plates laterad
of the shield. Posterior shield quadrilateral, short and a little wider

124 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

than the anterior shield, bears two pairs of branched hairs. On the
ventral side the mandibles are concealed inside of a slender tube with
flaring mouth, on its ventral side a pair of serrate blade-shaped ap-
pendages. Mandibles scimiter shaped, with an expanded serrate blade
at the tip. Palpi slender, segments of about equal length, thumb pap-
illa-like with several long hairs on its tip, claw short, thick and nearly
straight, slightly bifurcate at tip. Coxae very large, nearly touching
on the median line, coxae I with two branched hairs, coxae II and III
with one branched hair each. A pair of hairs opposite the interval
between coxae I and I! and coxae II and III. Spiracles between
coxae I and II. Two pairs of branched hairs posterior to coxae III.
Anus midway between coxae III and posterior margin. On the pos-
terior end of the body are four long branched hairs.

Legs stout and long, tarsi normal except tarsi III, which resem-
bles those of Sericothrombium scabrum.

Eggs. Vypical as to shape and appearance, orange in color.
Diameter 0.15 mm, fifty to one hundred in a mass.

Ten adults taken on June 16, 1917, in a small clearing on Big Is-
land, Lake Minnetonka, Minnesota, near a low marshy area. Some
were entering the soil to oviposit.

Attempts were made to rear this species from the eggs, but
failed. The eggs require about twenty-five days to hatch, the shell
rupturing and the legs of the embryo protruding after the eleventh
day. The larvae are easily distinguished from those of the other
species reared by their lighter yellowish color, and more elongate form.
Microtrombidium albovittatum. n.sp.

Adult female. Color scarlet, under parts, legs and cephalothorax
brighter. ~Size 1.65 to 2 mm long by 1 to 1.35 mm wide. Body
slightly constricted in the middle similar to Serico. scabrum, but more
slender and no posterior indentation, covered with slender plumose
hairs. Two deep transverse grooves in the wide anterior part of the
body, a third at the point of constriction, in the narrower posterior
part three pits connected by two shallow grooves, and forming a V-
shaped demarkation. Parallel to and just posterior to the anterior
groove is a wide white band, on each lateral margin posterior to this
band is a triangular white area with the base outward and apex ex-
tending between the second and third transverse grooves. On _ the
ventral surface the genital opening is opposite coxae IV. The anus
is half way between the genital opening and the posterior margin.

The cephalothorax is set in a deep anterior emargination, con-
cealed partly by the overhanging abdomen, longer than wide. Eyes

TROMBIDIIDAE OF MINNESOTA 125

sessile. Dorsal groove expanded at the posterior end. Palpi rather
slender, segment II twice as long as wide at widest part, segment II]
as long as wide, one-third as long as II, segment IV as long as III,
two claws at the tip, the inner smaller. Thumb almost cylindrical,
slightly clavate, longer than segment IV. On the outer side of seg-
ment IV are three heavy spines at the base of the thumb, and near
the base of the claw two long branched hairs projecting dorsally ; on the
inner side are two oblique rows of six or seven stout hairs each, legs
slender, tarsi I not swollen, a little more than three times as long as
wide, claws very long and slender, those of tarsi I much smaller than
those on the other tarsi.

One specimen was taken in a cultivated garden in Minneapolis,
along with Serico. scabrum on May 22, 1917, another at Fort Snelling
in low lands, along with Ew. locustarum and Serico. scabrum.

This species might easily be confused with Serico. scabrum were
it not for the white markings. Its habits also seem to be the same.
In the laboratory it was impossible to find any food which it would
take. On one specimen the white markings were more extensive than
described above, the white triangles extended along the margin of the
abdomen nearly to a transverse white band at the rear margin.

Microtrombidium nopal-rubrum, n.sp.

Adult female. Color, nopal red, lighter on the under side and legs.
Size 1.50 mm long by 1 mm wide. Body flattened and oval in outline,
wider in front, anterior edge deeply emarginate, posterior end rounded,
no constriction at the middle. Entire dorsal surface sunken, with
two deep anterior transverse grooves, two shallow median transverse
grooves, present or absent, and a large, shallow, posterior, convex area.
Ventral surface with genital pore opposite coxae [V. Anus just pos-
terior to genital pore. Body covered thickly with peculiar stout
branched hairs expanded at the top and turned backward. Muingled
with these, especially near margins of the body are short globose hairs.

Cephalothorax as wide as long, set into a deep emargination of the
abdomen so that it is entirely exposed. Clavate hairs on cephalo-
thorax, with ends turned forward. Eyes sessile. Dorsal groove ex-
panded on the posterior end. Palpi stout, and curved, segment II two
thirds as wide as long, segment III as wide as long, segment IV a third
longer than III, two stout terminal claws, the inner one smaller, thumb
stout and cylindrical, as long as segment IV. Segment IV has on the
inner surface a dorsal comb of stout hairs, also a double row of stout
hairs parallel to the dorsal edge. On the outer surface are clavate
hairs like those on the body. All other hairs are slender and barbed.

126 SEVENTEENTH Report STATE EntTomoLocist oF MINNESoTA—1918

Legs rather stout, legs I as long as the body, legs IV reach beyond
the body. Tarsi I three times as long as wide. Legs have clavate
hairs on the dorsal side, slender branched hairs on the other surfaces.

Male. Smaller than female, 1 mm long by 0.5 mm wide, lighter
colored, cephalothorax longer than wide, genital opening concealed with
long bristles.

A female collected in leaf mold under trees along Minnehaha Creek,
Minneapolis, May 2, 1917, also one male and one female collected in
similar material on Big Island, Lake Minnetonka, Minnesota, June 16,

1917.

Microtrombidium punctatum n.sp.

Male. Color, pale orange red, size 1.50 mm long by 0.90 wide,
body oval in outline, wider in front, not constricted at the middle,
anterior margin concave, posterior margin widely rounded. Body and
cephalothorax clothed sparsely with intermingled stout, blunt, barbed
hairs, and knobbed hairs, with the knobs bent backward, the upper
surface of the knob on these hairs is cuplike and filled with a soft
membranous mass. Legs with knobbed hairs on the outer edges and
slender barbed hairs on the inner edges. On the dorsum are six pairs:
of large, deep pits, but no grooves. On the venter the genital open-
ing a little posterior to coxae IV, three times as long as wide. Anus
the length of the genital opening posterior to it, very large and circular
in outline.

Cephalothorax large, wider than long, not hidden by the abdomen.
Eyes sessile, opposite the middle of the cephalothorax. Dorsal groove
expanded at the posterior extremity. Palpi stout and strongly flexed,
segment II not much swollen, a third longer than wide,
segment III as wide as long, segment IV longer than III, two long
slender claws on the tip, inner one smaller, thumb slightly clavate,
longer than segment IV. On the inner surface of segment IV is a
dorsal comb of stout spines, parallel to this is a row of six heavy spines
in line with the base of the smaller claw, several stout spines are placed
irregularly at the base of the thumb. On the outer surface of seg-
ment IV is a row of three heavy spines at the base of the thumb. Legs
stout, legs I not quite as long as the body, legs IV reach beyond the
body. Tarsi I somewhat swollen, three times as long as wide.

One specimen collected among fallen leaves in woodland, Minne-
haha Creek, Minneapolis, May 16, 1917.

Microtrombidium muscarum (Riley) (?)
Atoma parasiticum Latreille. 1806 (larva).
Astoma parasiticum Riley, 7th Missouri Rpt. p. 177; 1875.

TROMBIDIIDAE OF MINNESOTA 127

Trombidium parasiticum Murray—Econ. Ent. p. 129; 1877.

Trombidium muscarum Riley. Ist Rpt. U. S. Ent. Comm. p. 306;
i878s\\ Banks rans. 7Am> Mate Soc. Volk Zit spre2 13;
1894.

Microtrombidium muscarum Ewing. Ill. Univ. Studies, Vol. 3,
Paco, EGOS:

The adult of this species has not been collected in Minnesota but
must occur here, as what is probably the larva has been found three
separate times, twice on adult W. domestica, (April 8, 1916, and July
8, 1914), and once in a manure pile (August 11, 1914). They were
true trombidium larvae. The description follows:

Larva, partly engorged. Color scarlet, size 0.50 to 0.66 mm long
by 0.35 to 0.45 mm wide. Oval in outline, widest a little before the
middle, Dorsum with numerous branched hairs. On the anterior end
a large pentagonal chitinous shield widely rounded on the anterior
angle, three heavy spines near each of the lateral edges, two of these
branched, the middle one unbranched and borne in a large pit; a pair
of hairs near the anterior angle. Just laterad of this anterior shield,
on either side, are the paired eyes on small elliptical plates. Just pos-
terior is a narrow more or less spindle-shaped plate bearing a pair of
branched hairs. Ventral surface with fewer hairs. Coxae I and II
contiguous, with opening to tracheal system between. Coxae III sep-
arated from the others. Mouth parts completely hidden beneath the
dorsal plate. Mandibles concealed inside of a cylindrical sheath which
bears on its under surface two palmate appendages. Palpi short and
stout, segments subequal, segment IV ends in a bifurcate sword-shaped
claw, bearing a spine at its base. Thumb papilla-like, surmounted on
the tip by several very long finely branched hairs. Legs slender, claws
of tarsi normal, those of tarsus III like tarsi I and II.

Sericothrombium scabrum (Say)
Trombidium scabrum Say—J\. Acad: Nat. Sci. Phila., Vol. 2, pt. I,
prolselsZ i:
Le Conte, Comp. Writings of Say. Vol. 2, p. 16; 1859.
Banksy Drans. Am. Ent: Soc, Vol.-21*p. 212; 1894
bynes. Vl Unive Studies, Vol. 3, No:-0,p.90); 1909.
Adult female. Color, bright scarlet, pale on under side. Size,
2.25 mm to 5 mm long by 1.50 to4 mm wide. Body strongly constricted
in the middle, very wide in front, narrow behind, posterior edge
rounded with a prominent indentation at the median point. The
grooves on the dorsal surface form an angular figure 8. The ventral
surface has anterior transverse groove, followed by a second and a

128 SEVENTEENTH Report State Entomo.Locist or Mrinnesota—1l918

third arched groove which may join the second in the middle and pass
laterally below the hind coxae. The cephalothorax is set into a deep
anterior emarginatim on the ventral side and with it the first two pairs
of coxae; when at rest or disturbed the anterior legs and palpi are
curled into this emarginatim so as to be invisible from above. Coxae
III and IV are near the point of constriction. The genital opening is
opposite coxae 1V. The anus is just posterior to the genital opening.
Body thickly covered with stout, blunt, barbed hairs, giving it a velvety
appearance. The hairs on the legs and palpi are slender and taper at
the tip.

The cephalothorax is almost completely hidden by the projecting
abdomen. Dorsal groove with the expansion at the anterior end. Eyes
on rather long pedicels and placed rather far forward, a little posterior
to the level of the expansion of the dorsal groove. Palpi stout, and
somewhat swollen, segment IV as long as III, thumb as long as seg-
ments III and IV, swollen distally, one strong claw on the tip of seg-
ment IV, fine branched hairs on all the segments. Legs of moderate
length, tarsus 1 somewhat swollen, three times as long as wide.

Male. Smaller than female, 1.25 to 1.50 mm long by 1 mm wide,
abdomen more strongly constricted at the middle, and grooves more
strongly marked. Genital opening longer and narrower.

Nymph. Not reared.

Larva, unengorged. Color, scarlet; size 0.16 mm by 0.31 mm.
Dorsum with an anterior pentagonal chitinous shield. Three branched
spines at the lateral angle of this shield close together. Posterior
dorsal shield quadrilateral in outline and close to the anterior shield.
Ventral side, with mouth parts hidden from above by the dorsal shield.
Palpi short, and swollen, only one terminal claw, which is scimeter
shaped and bifurcate; papilla-like thumb bears several long hairs. The
thick, sharp mandibles have a heavy tooth at the base. On the ventral
side of the mandibular sheath is a pair of short, stout processes divided
brush-like into numerous long, fine branches. Coxae I and II con-
iiguous, each with two long branched hairs; elongate opening to
tracheal system between them. Coxae II] separated from the others
and with only one branched hair. Legs slender, tarsi I and II normal,
tarsi III as in Ew. locustarum larva. Anus near posterior margin, four
heavy spines on the posterior margin, each nearly a third as long as the
body.

Eggs. Spherical in outline. Shell smooth and shiny. Color
chrome yellow. Size 0.15 mm to 0.17 mm in diameter. About 300 to
400 placed in a cluster as in other species.

TROMBIDIIDAE OF MINNESOTA 129

This species has been collected in Hennepin, Ramsey, Otter Tail,
Roseau and Nicollet counties, and is probably distributed over the en-
tire state. This is undoubtedly the species which Banks calls Trom-
bidium seucium. It is the commonest and most evenly distributed
trombidium found in Minnesota, altho not so abundant in any given
locality. The minute, short, chunky, bright scarlet adult can be found
almost any day from early spring to midsummer, running about the
soil of cultivated fields. They move with a nervous energy looking into
every crack and crevice in search of food. Not only are they com-
mon in cultivated land, but also in woodland, among the fallen leaves,
on dry hillsides and in wet bottom lands. Sometimes one can collect
this species, Allothrombium pulvinus, Eu. locustarum and Micro. magni-
tarse in the same place. Occasionally one may be found climbing the
bark of a tree.

We have never yet seen one feeding in the open. On one occasion
they refused grasshopper eggs.

Oviposition has occurred in breeding jars on several occasions.
One lot of eggs was ‘aid on July 1. These hatched about July 15,
a nymph was found in the soil on August 13 but died before the
adult emerged. A second lot of eggs was laid on June 13, these
hatched on July 22. A third lot of eggs laid on May 22, hatched
about July 1. The rupturing of the egg shell occurred seven to ten
days after the eggs were laid. Ina fourth attempt to rear this species,
adults were fed on small insects collected by sweeping grass and
shrubbery. Engorgement was secured easily, but it was not possible
to find what insects were chosen for food. When fully engorged they
become very rotund and the stretched skin shiny. Egg masses were
placed on June 20 to 22 under leaves at the surface of the soil or
in the soil even to the depth of an inch. Each mass contained about
200 eggs of a lemon yellow color, becoming more orange colored with
the development of the embryo. After about seven to ten days the
shells began to rupture. About twenty-two days were required before
hatching took place.

It was found that these larvae would readily attack a white rat,
but not a young pigeon or a thirteen-lined gopher. On the rat they
burrowed into the skin and caused lesions similar to those caused by
chiggers on man.

The eggs are easily distinguished from those of the other common
species by their larger size and lemon yellow color.

Trombidium maculatum. n.sp.
Adult female. Color dark scarlet, an irregular transverse white

130 SEVENTEENTH REpoRT STATE ENTOMOLOGIST oF MINNESOTA—1918

band just anterior to the groove opposite median constriction of the
abdomen, the spines in this area white. Very much wider in front
than behind, size 2.5 mm by 1.5 mm. Abdomen overhangs the cephalo-
thorax slightly, clothed with stout, thickset tapering hairs, each with
numerous long branches. A shallow groove near the anterior mar-
gin, a second deep one at the median constriction, a third arched groove
posterior to this, with three pits forming a triangle near the posterior
end. Ventral surface of a creamy color except that portion posterior
to the last coxae. Cephalothorax set into an anterior emargination to-
gether with coxae I and II. Coxae III and IV near the median con-
striction, genital opening opposite coxae IV, anus two-thirds of dis-
tance from genital opening to margin of body.

Legs slender, tend to a creamy color except legs I which are scar-
let, legs I] shortest, legs [IV reach much beyond body. Tarsi I about
five times as long as wide. Covering hairs of legs slender.

Cephalothorax light colored—wider than long—Dorsal groove
with the expansion in the middle. Eyes stalked, about opposite the
expansion of the dorsal groove, sharp pointed at the top. Palpi short
and thick, segment II very much swollen, nearly as wide as long; seg-
ment III wider than long, about a third as long as I1; segment IV twice
as long as III, a very heavy tooth on the extremity, longer than the
segment; thumb slender, clavate and reaching beyond the end of the
claw; long, slender, branched hairs on segment IV reaching nearly to
tip of claw.

Male. Similar to female—size 1.4 by 0.95 mm. Legs more slen-
der, and grooves of body more marked. Outline of body is more
wedge-shaped.

Two males and a female taken in leaf covered humus under wild
raspberries, Big Island, Lake Minnetonka, Minnesota, June 16, 1917.

OnE GEARS.

Under this heading will be described the undetermined larva
which attacks man in Minnesota. It is obviously the larva of one of
the Trombidiidae and according to Oudemans (1912) would be the
larva of a Microtrombidium. It does not, however, conform to the
characters of one member of this genus, which we have bred and which
is described in this paper. These larvae will attack birds as well as
man. During the summer of 1916, large numbers of prairie chickens,
quail and pheasants were attacked by them on the Game Preserve at
Lake Minnetonka. They penetrated the skin so thickly about the neck,
anus and under the wings that immense areas of the skin were in-

TROMBIDIDAE OF MINNESOTA 131

flamed, and many birds were so weakened as to become victims of
dysentery and died. The mites did not bury themselves in the skin,
but inserted the mouth parts and filled with blood. Some were seen
fully engorged and walking away or dropping to the soil. When at-
tacking men they do not seem to bury themselves in the skin, and the
results of their bites are not so severe or extensive as usually described,
but are similar to those of poisonous insects. The small area of in-
flammation lasts for only a few days unless scratched or otherwise irri-
tated and then disappears. Individuals, however, differ in their sus-
ceptibility to these mites.

Description of larva: Nearly circular in outline, color scarlet;
size 0.25 by 0.17 mm. Dorsal surface with numerous long, stout barbed
hairs; a trapezoidal shield at the anterior end, about twice as wide as
long, and bearing four pairs of barbed hairs; paired eyes just laterad
of the shield. The heavy capitulum is well exposed from above, widely
petagonal in outline with the point forward, the mandibles protrud-
ing beyond it; a wide, shallow median groove extending its entire length.
Ventral side with numerous barbed. hairs, coxae close together, stig-
mata between coxae I and II, anus about half way between coxae III
and posterior margin of body. Mandibles enclosed in a more or less
cylindrical sheath. Palpi stout and curved toward median line, borne
at the lateral angle of the capitulum on the under side; segments II
and III about as wide as long, segment IV nearly twice as wide as long,
claw on segment IV long, stout and bifurcate, thumb stout and having
several long plumose hairs on its tip.

Legs stout with numerous barbed hairs.

BIBLIOGRAPHY

Banks, N. Some New American Acarina. Trans. Am. Ent. Soc. 21, pp.
209-229 ; 1894.

Banks, N. The Arcarina or Mites. Rept. No. 108, U. S. Dept. Agri., Office
of Secy. 1915.

Berlese, A. Trombidiidae—Redia—8, p. 291; 1912.

Chittenden, F. H. Harvest Mites or Chiggers—U. S. Farmers’ Bul. No.
671; 1915.

Ewing, H. E. Syst. and Biol. Study of the Acarina of Hl. Bul. Univ. of
TESZ, p: 1203 1909:

Murray, A. Economic Entomology, Aptera, London, 1897.

Osborn, H. and Underwood, L, M. Prelim. list of species of Acarina of N.
Am.—Can. Ent., 18, pp. 4-12; 1886.

Oudemans, A. C. Die bis jetzt bekannten larven von Thrombidiidae und
Erythraeidae—Zool. Jahrbiicher, Suppl. 14, pp. 1-230; 1912.

Riley and Johannsen. Handbook of M edical Entomology, p. 60; 1915.

Riley, C. V. Report U. S. Ent. Com.; 1878.

132 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

PLATE V

Allothrombiwn pulvinus

A—Dorsal view of adult female. x12
B—Ventral view of adult female. x12
C—Palpus of adult: x50

D—Fourth segment of palpus. x75
E—Mandible. x50

F—Blade of mandible. x260

G—Tip of tarsus I showing pulvillus. x75
H
I —Coxae III and IV of adult. x25

J —Hair from body of adult.

Eyes. x75

K—Dorsal surface of larva. xSO
L—-Ventral surface of larva. x80
M—Process on mandibular sheath. x490

N—Palpus of larva. x330

133

TROMBIDIIDAE OF MINNESOTA

PLATE V

134 SEVENTEENTH Report StaTE ENToMOLOGIST oF MINNESOTA—1918

PLATH VI

Hutronbidium locustarum.

A—Dorsal surface of female. x8
B—Venetral surface of female. x8
C—Palpus. x25

D—Segment IV of palpus. x50
E—-Tarsus I of adult. x25

W—HDyes. 55

G—Hair from body of adult. x55
H—Posterior dorsal plate of male. x12
I —Posterior dorsal plate of female. x12
J —Dorsal surface of larva. x150
i<—Ventral surface of larva. x150
L—Mouth parts of larva. x300
M—Segment IV of larval palpus. x600
N—Tarsus III of larva. x300

O—Engorged larva—dorsal surface. x25

TROMBIDIIDAE OF MINNESOTA

PLATE VI

135

136 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

PLATE VII

Sericotrombium scabrum.

or

A—Dorsal surface of female.
B—Ventral surface of female. x15
C—Palpus of adult. x30

D—lLeg I of adult. x30

E—Eyes. x50

F—Hair from body of adult. x350
G—Dorsai surface of larva. x100
H—Ventral surface of larva. x100

I —Segment IV of larval palpus. x400
J —Tarsus III of larva. x400

Ix—Tip of mandible of larva. x400
L—Process of mandibular sheath. x600

TROMBIDIIDAE OF MINNESOTA 137

PLATE VII

138

SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

PLATE VIII
Microtrombidium trianguluin.

A,—Dorsal surface of female. x16.
By—Palpus of adult. x65

C,—Segment IV of palpus, inner surface. x65
D,—Tarsus I of adult. x35

E,—Hair of body. x600

F'y—Hair from legs and palpus. x600
Gi—Dorsal surface of larva. x90

H,—Ventral surface of larva. x90

I, —Process from mandibular sheath of larva. x720.
Ji;—Mandible of larva. x630 al

Kk ,—Segment IV of palpus of larva. x360

Trombidium maculatum.

Ao—Dorsal surface of female. ~ x25
Bo—Palpus. x100

Ce—Tarsus I. x50

Do—Eye. x350

Ee

Feo—Hair from body. x450

Hair from body. x450.

TROMBIDIIDAE OF MINNESOTA 139

PLATE VIII

140 SEVENTEENTH Report STATE ENntTomoLocist oF MinNesota—1918

PLATE IX

Microtrombidium nopal-rubrum.

A,—Dorsal surface of female. x15
By—Palpus, inner surface. x60
Cy—Tarsus I. x30

D,—Hair from legs. x120
Ey—Hair from body. x120
Fy—Hair from body. x120
G1i—Hair from body. x120
H,—Hair from body. x120

I, —Hair from body. x120

Microtrombidiwm magnitarse.

Ae—Dorsal surface of female. x20
Bo—Palpus, inner surface. x30
Co—Tarsus I. x40

De—Hair from body.

Microtrombidium punctatum.

As—Dorsal surface of male. x15

33—Palpus, outer surface. x45

Cs—Segment IV of palpus, inner surface. x45
Ds—Tarsus I. x30

Bs
F3—Hair from legs and palpus. x150
G3—J3—Hairs from body. x150

Ks—Eye. x75

Hair from body. x150

141

TROMBIDIIDAE OF MINNESOTA

PLATE 1X

142 SEVENTEENTH Report STATE ENntTomoLocist oF MinnEesota—1918

PLATE X

Microtrombidium albovittatum.

Ai—Dorsal surface of female. x20
Bi—Palpus, inner surface. x60

C,;—Segment IV of palpus, outer surface. x60
D,—Tarsus:- I. x80!

E,—Bye.

Microtrombidium muscarum. (?)

Ao—Dorsal surface of partly engorged larva. x66
Bo—Ventral surface of partly engorged larva. x66
Co—Mouth .parts of larva. x333

Do—Segment IV of larval palpus. x666
Ee—Process from mandibular sheath, x1000
Fo—Tarsus III of larva. x200

TROMBIDIIDAE OF MINNESOTA 143

PLATE X

144 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

PLATH XI

“Chigger Mite.’
A—Dorsal view. x160
B—Ventral view. x160
C—Palpus. x240

THE HYMENOPTERA OF MINNESOTA*
By F. L. WasHBuRN

The Minnesota Entomologist’s reports issued between the years
1895 and 1901 comprise, amongst other subjects, treatises on certain
orders of insects as they occur in Minnesota. Dr. Lugger, State En-
tomologist during that period, issued one report on the Grasshoppers
of Minnesota, another on Butterflies and Moths, another on the Bee-
tles, and still another, the sixth and last, on the Bugs of the state. It
was evidently his intention, had he not been prevented by death, to
complete the series, issuing reports on Diptera, Hymenoptera and
possibly other groups of minor importance.

The writer published in 1905 a brief report on the Diptera, list-
ing perhaps not more than one-tenth of the species of two-winged flies
occurring in the state. Subsequently, a list of additional species was
issued. For several years, at times when other work permitted, he
has been working upon the Hymenoptera. The results of this work
are embodied in this publication.

In view of the fact that hitherto no special effort has been di-
rected towards the study of this group in Minnesota, and hence
comparatively little collecting has been done, it is gratifying to note
that our collection at this time includes as many species of wild bees as
have been taken in that favorite collecting ground of entomologists,
namely—the state of New Jersey.

Readers of this report should realize that securing anything ap-
proaching all the species occurring in Minnesota would mean many
years of collecting; hence no list of Minnesota species would be
approximately complete, which did not represent the work of a lifetime
in collecting in this state. We list all species collected and determined
to date, emphasizing in descriptive text those of economic importance.

In presenting this report on Hymenoptera, we take pleasure in
acknowledging the invaluable assistance of Mr. H. L. Viereck of
the United States Biological Survey, in identification of species, and
in various other lines connected with the technical part of the work.
The colored plates and drawings, except where noted, were made by
Miss I. L. Wood under the author’s direction. We acknowledge the
courtesy of the officers of the State Geological and Natural History
Survey of Connecticut in allowing us to use the drawings referred to

*Published with the approval of the Director as Paper No. 156, of the Journal
Series of the Minnesota Agricultural Experiment Station.

145

146 SEVENTEENTH Report State ENtTomoLocist or MinnNesota—l918

below. Mr. Warren Williamson, of this department, was of material
assistance in compiling material in the early part of the work.

We wish to acknowledge also material assistance in identifica-
tion of specimens afforded by S. A. Rohwer and associates, Dr. W. M.
Wheeler, Dri J. Chester Bradley, Dr. H» IT. Fernald, and Dr- ai
Swenk. Dr. H. J. Franklin identified most of the Bombids and species
in a few other groups. Dr. Headlee, of the New Jersey Station, kindly
loaned certain cuts previously used in a New Jersey report, Howard’s
Insect Book and in Insect Life. C. W. Hooker identified our Ophion-
int.

To serve students of Hymenoptera, a brief technical description
of each family is inserted and in explanation of same, descriptive fig-
ures used in “The Hymenoptera or Wasp-like Insects of Connecticut’’*
are printed herewith.

We have not hesitated to use technical matter from the Connecti-
cut volume wherever it was thought that it would be helpful, believ-
ing it to be the best work on the subject up to the date of its publica-
tion. Subsequent to that time, a certain amount of hymenopterous
literature has appeared, which has thrown additional light on classi-
fication and caused us to depart somewhat from the plan followed in
the Connecticut volume. The changes referred to will be apparent
to the student.

It is believed that with the brief technical synopsis, introducing
each family and the figures above alluded to for reference, there is no
pressing need of a synoptical key or a glossary.

THE MINNESOTA COLLECTION

Experts in Hymenoptera pronounce our collection one of the best
in the country outside of some of the larger eastern collections, and
that of the Federal Bureau. Dr. Lugger, however, habitually neglected
to place locality labels with his specimens. While he probably knew
personally exactly where each specimen was collected, he did not appear
to be impressed with the necessity of leaving a record for those who
came after him. The result is that we have very many species in the
collection, without doubt to be credited to Minnesota, which neverthe-
less we hesitate to include in our faunal list. Many of the boxes in
the Lugger collection are filled with specimens undoubtedly taken here,

*State of Connecticut State Geographical and Natural History Survey Bulletin
No. 22, Guide to the Insects of Connecticut, prepared under direction of W. E. Brit-
ton, State Entomologist, by H. L. Viereck with the collaboration of A. D. MacGillivray,
Cc. T. Brues, W. M. Wheeler and S. A. Rohwer.

THE HyMENOPTERA OF MINNESOTA 147

though lacking the locality label. We have, in this publication, cred-
ited to our state fauna only those individuals labelled as collected here,
or which have been reported on indisputable authority as occurring
within the state. Manifestly many times more species occur in this
state than are indicated in this publication.

An excellent account of egg laying of gall flies may be found in
Volume 3, Proceedings of the Entomological Society of Washington
and in Kelloge’s “American Insects.” Howard’s “Insect Book,” pp.
26-28 has an interesting description of the Vespidae, while the valu-
able observations of the Peckhams may be found in the Wisconsin
Geological and Natural History Survey Bulletin No. 2, Scientific Series
No. 1. In this work under the headings, “The Little Fly Catchers,”
“The Toilers of the Night,” “Enemies of the Orthoptera,” “The Bug
Hunters,” “Some Grave Diggers,” and other more technical titles, they
discuss the O-vrybelidae, the Crabronidae, the Trypoxylonidae, the
Sphecidae, the Astatidae, Cerceridae and other families. The student
is referred to Page 12 of Howard’s Insect Book and to Volume VI of
the Cambridge Natural History for the habits of Andrena. Howard’s
Insect Book also contains a good account of the leaf-cutting bee, the
life history of bumble bees and the habits of the small carpenter bee,
as well as furnishing the student with a large series of photographs
of pinned Hymenoptera. The student of the order cannot afford to
miss the valuable material found in Fabre’s “The Bramble Bees and
Others,” “The Mason Bees,” and “The Hunting Wasps.” An abun-
dance of other matter of a popular nature pertaining to Hymenoptera
is available to students, and technical synopses of the group and de-
scriptions of genera and species occur in our leading entomological
journals.

CHARACTERISTICS OF HYMENOPTERA

This order is characterized by the presence of four wings, mem-
branous, and for the most part, translucent, and with but few cells.
The hind wing of each side, is, in flight, more or less firmly fastened
to the front wing by a series of hooks on the front edge of the former,
which articulates with a fold on the rear édge of the front wing. The
mouth parts of the adults are adapted for biting and sucking. The
ovipositor of the female is usually modified to form a sting, piercer or
saw.

Hymenopterous insects have a complete metamorphosis, i.e., dis-
tinct egg, larval, pupal and adult stages. The larva, frequently re-

148 SEVENTEENTH Report STATE ENtToMoLocist or MINNESoTA—1918

ferred to as “grub” or “maggot” is generally, but not always (notably
sawfly larva), footless. The pupal stage is quiescent and exhibits all
the appendages of the adult enclosed in a pupal sheath. This pupa
may or may not be contained in a cocoon. In the bees and wasps the
pupal stage is passed in the comb. Of all the orders of insects, the
Hymenoptera contains perhaps the most species and amongst them
some forms which have a most important bearing upon man’s welfare.

A student of Hymenoptera is impressed with the fact that apart
from the highly useful activities of the honey bee, the two most 1m-
portant and useful functions exhibited by the group are those of polli-
nation or cross-fertilization so necessary in the production of good
seed and good fruit, and of parasitism, by which characteristic
the number of injurious insects is materially reduced.

The modifications of flowers to bring about cross-fertilization by
insects, and to prevent self-fertilization, are many and striking. In
an observation covering twenty-six days, 275 species of insects were
observed to visit the flowers of Pasturaca sativa; of these, 173 species
belonged to Hymenoptera. Of 115 species of insects visiting milk-
weed, 52 were Hymenoptera and 42 Diptera. Of 87 species observed
on the flowers of willow during 7 days, 43 were Hymenoptera. It
will be noted that this group is an important one in this connection.

The services of Hymenoptera in the matter of parasitism have been
referred to above. Suffice it to say that the Hessian fly, Tussock moth,
scale insects, plant lice and a host of others are kept within bounds by
the activity of hymenopterous parasites. These are chiefly occupied
in destroying the tribes of vegetarian insects; 63 species attack a cer-
tain species of moth; the American Tent Caterpillar is said to be para-
sitized by 12 species of Hymenoptera, to say nothing of attacks upon
them by Dipterous parasites. [From a single caterpillar of the Cab-
bage Moth (Plusia brassicae) over 3,000 individuals of Copidosoma
truncatellum have been bred by Girard.

On the other hand, we find in this group, many injurious forms
such as the larch sawfly and other sawflies and many gall makers.

IXPLANATION OF COLORED PLATH 1

Cimbex americana Leach.

Trogus (Automalus) quebeccensis Prov.
Perilampus hyalinus Say.

Tetrachrysis caerulans F.

Odynerus molestus Sauss.

Vespula vulgaris L.

Chalybion caeruleum L.

AA Or WD

BUR. ENGRAVING, MPLS.

1. L. WOOD, DEL.

MINNESOTA HYMENOPTERA

Plate 1.

f a i. ne

des a vale =

ee eee Saag! ee

149

THE HyMENOPTERA OF MINNESOTA

Pitan BN VEE)
2 7 Ny)

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Sy. ' -douemAyT oq} Jo AUB JO UOT}dIIOSep ur posn
; LytLilt !
JO HY! | | i SUI} SUTjOId19}UT UI [NjJosn puNnos oq IIA
J LZ PUS 9Z SSA /18S9Qll MAPU0OLIId °9% “SIA
M10 -> prone

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Ba Net sans go Ops
Be ag G9 O HF
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S98 oka G0? He

150 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

In the following pages the order is divided into two groups, the
Chalastogastra, represented by the first ten families, all included in the
one superfamily Tenthredinoidea and the Clistogastra, which embraces
all the remaining superfamilies.

NoMENCLATURE OF WING ParTs IN THE DRAWING OF

Pteronidea ribesi

OLD SYSTEM COMSTOCK-NEEDHAM SYSTEM
Front Wings

Veins Veins
Costal Costa
Subcostal Sc-+-R+M
Median Cubitus
Anal Ist A+2nd A
Accessory 3d A and 2d A
Inferior Hind margin (not a vein)
Radial Rs—R,
Cubital M—R,+,+M,
Subdiscal m and M,
Transverse costal Sc,
Transverse radial Radial cross-vein (7)
First transverse cubital Radio-medial cross-vein (7-m)
Second transverse cubital Free part of R;
Third transverse cubital Free part of R,
Basal Medio-cubital cross-vein (m-cu)
First recurrent M3t,
Second recurrent Transverse part of M,
First transverse median M,+Cu,
Second transverse median M,
Transverse lanceolate Free part of 2d A

Cells Cells
Costal Grandesc;
Subcostal M
Median Cu+Cu,
Lanceolate Ist A + 2d 2d A and Ist 2d A

Usually the wing area covered by 1st
A, 2d A, and 3d A

Anal 3d A, or Ist 2d A+ 3d A
Radial Rit.
Appendiculate Appendiculate
First cubital R

Second cubital Re

Third cubital R,

Fourth cubital R,;

First discal M,

Second discal Ist M,

Third discal M,;

First posterior M,

Second posterior 2d M,;

THe HyMENOPTERA OF MINNESOTA

Hind Wings

Veins Veins
Costal Costa
Subcostal R+M
Median Cubitus
Anal Free part of Ist A
Accessory neespartron edu
Radial R;—R,
Axillary 3d A
Cubital M—R,t+,+M,
Subdiscal m and M,
First transverse cubital M
Second transverse cubital R,
First recurrent Medio-cubital cross-vein (m-cu)
Second recurrent Transverse part of M,
Cells Cells
Costal C+Se,
Subcostal M
Median M:+ Cu+Cu,
Lanceolate sie ZN
Anal 2d A+ 3d A
Radial Rjt.
First cubital R+Ry4;
Second cubital Rk,
Lower discal M,+1st M,
First posterior M,
Second posterior 2d M,

KEY TO SUPERFAMILIES.

1. A deep constriction at the base of the first abdominal segment,* conspicuously

separating the abdomen from the thorax.

No marked constriction at the base of the abdomen, ‘the thorax and anterior

abdominal segments being approximately equal in breadth.

151

to

Tenthredinoidea Page 152

2. First abdominal segment* (sometimes also the second) forming a lens-shaped
scale or knot (petiole), strongly differentiated from the remaining abdominal

segments (gaster) : Formicoidea Page 198
Abdominal segments not strongly differentiated as petiole and gaster 3
3. Mesothorax anteriorly without the free prepectus shown in illustration of
Chalecidoidea (ig. 66) 4
Mesothorax anteriorly with a prepectus as shown in Fig. “66; usually winged,
with venation reduced to a minimum as in Fig. 65; usually less than 3 mm.
length and metallic. . i ; ; Chalcidoidea Page 180
4..Tegulae present, wings nea ell devareped: sometimes vestigal or lost Dd
Tegulae ES wines epnely absent, habitus es as in Ee
forms. e
5. Pronotum ach its hia vantes or eeubeneles fnnigent ha a werent aie Ghar
tangent to anterior edge of teulae, touching or underlying tegulae 6
Pronotum with its hind angles or tubercles always distinctly remote from
tegulae. 2 : 5 : 5 12
6. Body not flea- like he ‘ F us
Body flea-like; trochanters usually, composed of a single joint; wings usually
with a characteristic venation as shown in Vig. 65. . : Cynipoidea Page 177

*In all Hymenoptera the segment which is morphologically the first abdominal
segment (propodeum) is intimately fused with the thorax, of which it seems to be a
part. In this work, the general usage of descriptive writers is followed, and the
segment which is apparently the first abdominal segment, though morphologically the

second, is uniformly called the first abdominal segment.

IisZ SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA-—1918

Wings with at least basal, median and submedian veins present, usually with
venation well developed as shown in Fig. 40. 5 8
Wings usually without veins or with only subcosta and part of ‘radius present,
rarely as in Fig. 40, or as in figure of Pelecinus in Packard’s Guide.
Serphoidea Page 195

8. Trochanters composed of two joints. : : Tchneumonoidea Page 164
Trochanters composed of one joint ; g ; 5 : i : 3 op 4
9. Body not flea-like, not compressed ; 2 a a 5 = : ky)
Body flea-like, compressed as in winged forms. : ‘ Cynipoidea Page 177
10. Body not densely hairy A ; : 5 2 : ; : F ‘ Be eal
Body densely hairy : ‘ : : , ‘ ; Vespoidea Page 204
1i. First abdominal segment aipocied : ; i Ichneumonoidea Page 164
First abdominal segment not elbowed : e ; E Serphoidea Page 195
12. Hairs of dorsulum simple, not branched or plumose_. : o 13
Hairs of dorsulum branched or plumose : : : 3 Apoidea Page 223
13. Abdomen with more than three segments visible, segments beyond third not
hidden. . : A Sphecoidea Page 215

Abdomen with three segments visible, seg ments beyond third hidden
Chrysidoidea Page 203

14. Cutting edge of mandibles turned inward, their tips meeting or overlapping
when mandibles are fiexed toward mouth. é 3 Vespoidea Page 204
Cutting edge of mandibles turned outward, their tips usually neither meetin
nor overlapping when mandibles are flexed toward mouth.

Ichneumonoidea’ Page 164

CHALASTOGASTRA
‘TENTHREDINOIDEA

This is that part of the Hymenoptera known as the Phytophaga,
Phyllophaga, Tenthredinoidea or Saw-flies and Horn Tails or Ten-
thredinoidea and Siricoidea. Lately, S. A. Rohwer' has split up this
complex group into four Superfamilies—Megalodontoidea, Oryssoidea,
Siricoidea and Tenthredinoidea. The first of these superfamilies is
represented in the following pages by the Megalodontidae, Cephidae
and Xyelidae, the second by the Oryssidae, the third by the Xiphydrii-
dae and the Siricidae, the fourth by the Cimbicidae,” Areidae
Diprionidae, Tenthredinidae and Pterygophoridae.

The suborder includes all those individuals which feed upon
vegetable tissue, either directly as in the case of the saw-flies which eat
practically the entire leaf, or indirectly as with the gall flies, where
by the injection of some active irritating or stimulating agent, or by
similar effect induced by the presence of the egg or eggs or larva in
the plant tissue, produce distorted growths in and upon which the
larva feeds until maturity. The galls on willow, oak, rose, goldenrod
and some of the other plants and trees are examples of these growths.

Many members of the group are injurious, and in some of the
torms the ovipositor is modified to form a pair of saw-like plates
lying inside of, and protected by a sheath. The insects so character-
ized, are compact with the thorax and abdomen about equal in trans-

11911 Proc. Ent. Soc. Washington 138 (215-226).

Tue HyMENOPTERA oF MINNESOTA 153

kAirve/ dine. >

VITYOSHA M78.

l

Molormund/, Mune

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Coxgl’ fine \ N COxa/ sohef

oS VIS COXGIC

A fostocelar lize.
| Oa CM ociijar hive
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pe--l- /
Aiitemal Purr on 1 Tes
AT. sy 2 x2 Sypraorbital ine.
\ Lateral oceler
| lee ee "72. :
t i FOU Mie.
aN
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8 | | Antemroc lier Wie.

aC.
Y

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8
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Mater Octiigr We |
esa ear pie eee | |
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Loferel ocellar
WTEC.

— “7 &/ locejoitel bine.

Qs Mire. a) hire.

LVS LUT ‘a

Fig. 27. Exochilum morio : different views of head, thorax and propodeum, From
Connecticut Hymenoptera.

154 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

verse diameter. The abdomen is closely applied to the thorax by its
entire width. This condition is described by the expression “abdo-
men sessile” (not stalked). The wings are folded over the abdomen
when the insect is not in flight.

The larvae are unmistakable; they are either slug-like and slimy,
or resemble caterpillars very closely with the exception of having more
than five pairs of prolegs.

Larvae of this group need not be confused with caterpillars of
Lepidoptera, for saw-fly caterpillars have from eighteen to twenty-two

Fig. 28. Macrophya cassandra Kirby: female.

prolegs and these have no circlet of hooks as in Lepidoptera. The
former larvae move more slowly than the true caterpillars of the
Lepidoptera and they frequently assume grotesque postures never
taken by true caterpillars. When disturbed, they sometimes curl up,
lying on their sides. They are in some species covered with slime,
or exude a disagreeable liquid, and often change their color dur-
ing larval life.

Tenthredinid larvae generally change to the pupal stage in a
cocoon. There may also be an outer
cocoon, hard and coarse, and within that,
one of finer texture.

This group may perhaps be regarded
as a connecting link between the Lepi-
doptera and the Hymenoptera.

The superfamily contains the most
injurious individuals of the order. The

species are largely confined to the tem-

Fig. 29. EHiphytes mellipes -
fc Norton; female. perate AoE:

THE HyMENOPTERA OF MINNESOTA 155

MEGALODONTIDAE

Hind margin of the pronotum, or collar, straight or nearly so, being nearly the
shortest distance between the fore margins of the tegulae; dorsulum never extending
much beyond the fore margins of the tegulae; proepimeron wanting; first perapterum
wanting; fore tibiae with two spurs.

Inhabit woods, flying in
the sun, settling on leaves
and occasionally, but rare-
ly on flowers. Larvae
smooth, cylindrical, with
six short articulate and no
prehensile legs. Feed on
leaves of trees and inhabit
webs of their own making.
Pupa changes in a silken
cocoon on the stem of the
tree it inhabits, or on the
ground. IJtycorsia discolor

Cress, and Pamphilus per-
Fig. 30. Sterictiphora johnsoni MacGill; male. sicus MacG. occur in

a “sy

Minnesota.

CEPEEDAE

Hind margin of the pronotum, dorsulum and proepimeron as in Megalodontidae;
first perapterum present and seen a short distance below the tegulae as a small free
plate; fore tibiae with one spur; basal joints of the flagel separate; intercostal vein
wanting, radial cell with one cross vein; species slender and elongate.

Cephus pygameus Linn., is known as a wheat-stem borer, an in-
troduced insect; in Europe it attacks corn. Another form, Janus
integer Nort., bores in pith of currant. Another works in blackber-
ries, entering at the bottom and boring upward.

Janus abbreviatus Say, 1s a Minnesota species.

XYELIDAE

Hind margin of pronotum, dorsulum, proepimeron and first perapterum as in
Cephidae; fore tibiae with two spurs; basal joints of the flagel consolidated into a
long basal joint; intercostal vein present, radial cell with two cross veins; species
robust. Larva footless.

Imagoes appear early in the year, February, March and April,
deposit their eggs and disappear, so that few specimens are taken
and only the common forms known. Newman says of the group:
“Inhabits fir trees, occasionally settling on umbelliferous plants.”
Ent. Mag. II, p. 408, 1834. Dyar, however, is reported as finding

156 SEVENTEENTH Report STATE ENtTomMoLocist oF MINNESOTA—1918

one species upon hickory and butternut in New Jersey and the larva
of another species is reported as found upon the leaves of elm. The
iarva of Xycla minor has been found on pine. The larvae feed on the
leaves of the numerous elms found along the walks on the College
Campus at Saint Anthony Park. The adults are very inactive, so
much so, in fact, that they will lie still and allow themselves to be
crushed under foot on the walks. When they are disturbed in such a

way as to be compelled to use their wings, they have a slow lumbering

Fig. 31. Tenthredinid larvae, Craesus latitarsus Nort. on birch, showing a char-
neteristic attitude—From lIIlymenoptera of Connecticut.

flight and soon alight again; that is, the generalized condition of their
wings, as regards the number and arrangement of their veins and
trusses is confirmed by field observations, and proves that this insect
not only has wings that are poorly fitted for
a rapid flight, but that in fact it is an ex-
tremely poor flyer.

This is a small family embracing five gen-
era and a limited number of species which
are confined mainly to the American fauna.
It is easily separated from all other Hymen-
optera by the presence in its wing of the

free part of the vein R» The family con-
tains, at least so far as their wing vena-

; 4 ; Fig. 32. Cimbex americana
tion is concerned, the most generalized Leach. Another position as-

‘S sumed by saw-fly larvae.—
Hymenoptera known. From Hymenoptera of Con-
necticut.

THE HyMENOPTERA OF MINNESOTA 157

ORYSSIDAE

Hind margin of the prono-
tum strongly curved, dorsu-
lum extending well beyond
the fore margins of the teg-
ulae; metanotum concealed,
metapostnotum present and
large; antennae inserted
much below the apparent
elypeus; propodeum not di-
vided; proepimeron wanting;
fore wings with two cubital
cells.

Only one genus oc-
curs) in. this family,
Oryssus, of which there
are but a few rare spe-
cies: 0. sayi West,. is
found in Minnesota.

Fig. 38. Oryssus sayi West.

SIRICIDAE

Hind margin of pronotum and mesonotum as in Oryssidae; metanotum always
present, altho the metapostnotum is sometimes concealed; antennae inserted
above the clypeus; fore wings with more than two cubital cells; scutel completely
separated from the mesoscutum by a suture; proepimeron wanting, fore tibiae with
one apical spur; sheath exserted beyond the tip of the abdomen; cubitus joining the
basal vein much below the costa; notauli wanting, mesoscutum with oblique sutures
from the tegulae to the fore margin of the scutel; pronotum large, perpendicular
anteriorly and angulate laterally ; apex of abdomen with a triangular plate; fore wings
without an intercostal vein.

The ovipositor is held projecting backward from the extremity
of the body. Looks like a powerful sting. It is much longer than it
appears, as it is attached not
to apex of body but far forward,
to the under surface. It consists
of a pair of elongate sheaths,
which are easily separable
though they wrap together and
enclose a slender tube. This
tube is rigid and quite straight ;
tho appearing solid, it is really
composed of two very per-
fectly adjusted laminae and a
third arched piece or roof. The
two lower laminae are called
spiculae; they are serrated or

grooved in a peculiar manner

Fig. 384. Urocerus albicornis Fab.

158 SEVENTEENTH Report STATE ENtomMoLocist oF MINnNESoTA—1918

near the tip, and altho so closely adjusted to the borer or upper
piece of the tube as to appear to form one solid whole with it, they are
said to be capable of separate motion.

The Siricidae are the Uroceridae of authors. Something like
fifty species are known in this country, amongst them occurs the well-
known Pigeon Tremex, 7. columba.

The females of this species have a boring ovipositor or horn, pro-
jecting from the abdomen. With this, a hole is drilled in solid wood
and an egg is deposited therein. This pest attacks apple, maple, beech,
oak, elm, pear and other trees ; is apparently partial to the elm. It is kept
fairly well in check by parasites. Females, when egg-laying,
are sometimes unable to withdraw their ovipositors and are prisoners
until death relieves them. The larva, when full grown, is 1% inches
long; it transforms in a cocoon made of silk and fine chips, and when
ready to emerge, gnaws through the bark and flies away.

The genus Sirex is a wood borer and may pass so long a period
in wood that it is brought into a house in furniture. An instance is
cited where from wood, supposedly brought from Canada and made
into a house in England, Sirex emerged, to the great terror of the oc-
cupants. Sirex is often found in dried wood incased in metal, and
has been known to gnaw its way through the metal. Tremex columba
L., Sirex edwardsii Brulle, and Urocerus albicornis Fab. occur in this
state.

XxTPAYDRWDAE

Hind margin of pronotum, mesonotum, metanotum, metapostnotum, antennae,
forewings, scutel, proepimeron, spurs of fore tibiae, exsertion of the sheath and junc-
tion of the cubitus with the basal vein, as in Siricidae; notauli present; mesoscutum
without oblique sutures from the tegulae to the fore margin of the scutel; pronotum
very short medially and not angulate laterally; apex of abdomen normal; fore wings
with an intercostal vein.

Larva without feet. Inhabits and lives on the dead or dying
wood of various trees. Pupa changes in the same situation.

Xiphydria maculata Say and X. erythrogastra Ashm. are found
in Minnesota.

CIMBICIDAE

Hind margin of pronotum, mesonotum, metanotum, metapostnotum, insertion
of antennae and number of cubital cells in fore wings as in Siricidae; scutel never
completely separated from the mesoscutum by a suture, the suture always wanting
laterally, proepimeron present; fore tibiae with two apical spurs; cubitus joining or
touching the basal vein very close to the costa; mesoprescutum always present; first
perapterum present; abdomen sharply angled laterally, the tergites, laterally with
a dorsal and ventral aspect; antennae clavate.

The American Sawfly, or Elm Sawfly, Cimbex americana, is a
common species of general distribution, feeding on willow, basswood,
elm, birch and allied trees. The yellowish green larva has a black

THE HyMENOPTERA OF MINNESOTA 159

stripe along the middle of the back. Eggs are laid in June and the
winter is spent below the surface of the ground, in the larval stage,
not changing to pupa until spring. This species, normally destruc-
tive, has been observed to prey upon Gypsy Moth caterpillars (The
Gypsy Moth, Report of Forbush and Fernald, Mass. State Bd. Ag.
1896, p. 379). For an illustration of the larva of this form see Fig. 32.
The adult is shown on colored plate 1.

ARGIDAE

Agrees with the preceding description of Cimbicidae except as follows: Abdomen
not sharply angled laterally; antennae not clavate; sternauli or a suture separating
the mesosternum from the mesoepisternum, present; hind coxae adjoining or nearly
so; antennae three jointed.

The Purslane Sawfly, Aprosthema sabriskei Webster, occurring
commonly in Minnesota, is an interesting form in that it is sometimes

quite effective in checking the purslane. The eggs are deposited by
the female in the edges of the leaves. The larvae work within the
leaf between the two surfaces. The pupal stage occurs in the ground
and lasts about seven days.

Other Minnesota
species are Arge cae-
rulea Nort., the larva
feeding on white
birch; A. clavicornis
F;, A. humeralis
Beauv., A. scapularis
Klug, A. mcLeayi
Leach, A. pectoralis
Leach, A. dulciana
Say, and Stericto-

phora johnsoni MacG.

DIPRIONIDAE

Agrees with the preceding description of Argidae except as follows: sternauli
wanting; antennae more than six-jointed, furthermore, the first discoidal cell is not
petiolate, the mesoepimeron is divided into two plates with the sculpture of the dor-
sal one similar to that of the mesoepisternum, proepisternum not divided into two
plates; antennae many jointed, serrate in the female, pectinate in the male.

The larva feed on various pines and on fir. Diprion abboti some-
times defoliates branches of pine. The species has the habit of throw-
ing back head and tail when disturbed. D. abietes feeds, in companies,
on fir leaves until full grown. The whitish, tough cocoons often ad-
here to the leaves until the following season. Both of these species
may be quite destructive. D. pinetum, occurs in Minnesota, the larva

feeding on pine.

160 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

TENTHREDINIDAE
Agrees with the preceding description of Diprionidae except as follows: Meso-
episternum not divided into plates; proepisternum divided into two plates; antennae
seven to twelve-jointed, never serrate or pectinate.

Characterized by a large number of species, at least 2,000 being
known, amongst them some of our most common pests, for example,
the pear and cher-
ry slug, larch saw-
fly, currant worm,
the imported and
native, the former
being green and
black, spotted in the

adult larval stage,

Fig. 36. Lygaeonematus erichsoni Hartig. The Larch while the latter,

SENN with the excep-

tions of its black

head, is all green. In this family occur the rose slugs, raspberry slug,
pine sawfly and other pests.

Eggs are laid in slits cut by females in the leaf of host plant; in
currants, gooseberries and some other plants the eggs are laid on the
under side of the leaf. The larvae of some of the species “skeletonize”

the leaf, eating only the softer tissues, while others, like the currant

Fig. 37. Lygaeonematus erichsoni Hartig. The Larch Sawfly, male and female
and tips of abdomens.

THE HyMENOPTERA OF MINNESOTA 161

worm, eat the leaf entire. When full grown, the larvae make an
oval parchment-like cocoon which may be attached to host plant or
just below the surface of the ground.

Several species work on pine, others on strawberries, one on
alder—on Cornus, oak, maple, etc. Two attack willows. One species
is found on butternut. Another bores into the leaf stem of sugar
maple. At least one species is known to work on cranberry. Still
others make galls and two or more are known to be leaf rollers. One
feeds on poison ivy, and another feeds on sweet potato.

The family is referred to as “sawflies” because the females have
saw-like ovipositors, the ovipositor represented by a pair of stylets,
each serrate on outer margin.

Fig. 38. Tenthredella lobata Norton: female.

The larch sawfly, Lygaeonematus erichsonii is a menace to the
tamaracks of the northern part of the United States and Canada.

The effect of the attacks of the pear and cherry slug may be so
severe as to cause the leaves of these trees to brown and fall to the
ground in the middle of the summer. Fortunately, this pest of the
orchardist is easily destroyed, yielding readily to any of the arsenical
insecticides, to hellebore or pyrethrum, to dusting with air-slaked lime,
or even with road dust.

162 SEVENTEENTH Report STATE ENTOMOLOGIST OF M1NNESOoTA—1918

The imported or common currant worm occurs in this family,
a well-known pest of currants and gooseberries, stripping the leaves
from the bushes if not promptly checked. It is particularly destructive
in that its attacks are fre-
quently not observed until
too late to save the foliage.
The yellow-spotted willow
slug, Nematus ventralis
Say, is a common pest of
the willow. The larva is
dark with yellow spots.

Minnesota species: Em-
phytes mellipes Nort.
Fig. 39. Tenthredella verticalis Say: male. Pteronidea ribesi Scop P
ventralis Say, Lygaeonematus erichsonii; Hartig (larva feeds on Euro-
pean and American Larch).

Allantus basilaris Say, Macrophya lineata Nort., M. cassandra
Kirby, M. fulignosus Nort., Croesus latitarsus Nort., Tenthredella
grandis Nort., T. rufopectus Nort., T. lobata Nort., T. tricolor Nort.,
T. verticalis Say, Loderus albifrons Nort., Dolerus apricus Nort., D.
aprilis Nort., D. bicolor Beauv., D. similis Nort., D. unicolor Beauv.,
Tomostethus bardus Say. Viereck took Fenusa sp. Aug. 13 in St.
Louis County, and Schizocerus sp. in Sept. in Rock County.

PTERY GOPHORIDAE

Agrees with the description of Cimbicidae except as follows: First perapterum
present, sternauli or the suture separating the mesosternum from the mesoepisternum
wanting.

Acordulecera dorsalis Say, black, with white feet, is said to be

common in Indiana. A specimen in our collection is labelled “Va.”

163

THe HyMENOPTERA OF MINNESOTA

‘uuoD jo BiajdouemAFY oY, WO1y—

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SN -9SN 9q []IM UONBAISNI[I OU :10gnuzuao sajazAjquep ‘OF ‘StL “hy Vig y)} --xtypootuy
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L

aes GL: PAY SLL)

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LMM ALCO:
HY 274A “L100 Oa ae
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anid, dS

smpey
peurbseys YALE

164 SEVENTEENTH Report STATE ENToMoLOGIsStT oF MINNEsota—1918
NOMENCLATURE OF WING PARTS IN THE DRAWING OF

Amblyteles centrator

OLD SYSTEM COMSTOCK-NEEDHAM SYSTEM
V eins Veins
Costa subcostal Costa (C)+Sce+R+M
(In the Ichneumonoidea consid- .

ered in this work these veins are
usually seemingly but not actually

coalescent.)
First transverse cubital. r-m and Rs
Second transverse cubital R,
Cubital My. and R»,+ M,
First recurrent M.ty
Second recurrent Transverse part of M, or first abscissa
of M,
Basal M and m-cu
Subdiscoidal mand M,
Abbreviated cubital or stump M
Externomedial Cu
Da § 1st abscissa M,
Discoidal (2d and 3d abscissa M;

Transverse median of fore wings, or M,+Cu,
nervulus

Marginal or S 1st abscissa Radial cross-vein
radius (2d and 3d abscissa R,
Transverse median of hind wings, or
nervellus M;
Cells Cells
Areolet Rats
Cubitodiscoidal Wiste Roataixat Vy
CEISTOGASERA

SuporpER ICHNEUMONOIDEA

Trochanters are composed of one or two joints, the first abdominal segment is
elbowed and the cutting edge of the mandible, in some groups, is turned outward.
Wings usually with at least the basal, median and submedian veins present; body
never flea-like; pronotum with its hind angles or tubercles tangent to a vertical line
drawn tangent to the anterior edge of the tegulae and touching or underlying the
latter; tegulae and wings usually present, sometimes vestigeal or lost. Where the
tegulae and wings are wanting, the habitus is as in the-winged forms, the body is not
densely hairy and the first abdominal segment is elbowed; mesothorax anteriorly
without a free prepectus, first and second abdominal segments never developed into
a lens-shaped scale or into a node,

This is the most important group of Hymenoptera, in that it con-
tains the bulk of the useful parasites for which the order is noted.

THE HyMENoPTERA OF MINNESOTA 165

There are over 1,200 species of the suborder in Great Britain
alone, and probably more than 6,000 described species. Unquestion-
ably, there are more species still unknown. ‘The tropics, for example,
offer a field practically unworked.

The larvae are all
parasitic, principally
on caterpillars, de-
stroying enor-
mous numbers of
these pests. Some
attack spiders.

Attacks by these
parasites are not con-
fined to land species,
for one [European
form, Agriotypus ar-
matus, 1s aquatic, go-
ing under the water
and remaining there

for a considerable
period in order to lay
lig. 41. Cocoons of a Vipionid Apanteles (Pro- .
topanteles) congregatus, Say on Young Tobacco Worm. its eggs on larvae of
Natural size.—Courtesy of the Conn. Ag. Exp. Sta. anys
caddis flies.

A single genus, Aphidius, contains parasites on plum louse, cur-
rant, rose and wheat lice, as well as lice infesting cherry, willow, pop-
lar and cabbage.

Breathing in the larval stage is effected by osmosis between the
body of the parasite and the lymph or blood of its host in which it lies.

VIPIONIDAE

Cutting edge of mandibles turned inward, their tip meeting or overlapping, when
the mandibles are flexed toward the mouth ; mesothorax with its sternum and pleurae,
or at least the latter, not divided into an anterior and posterior portion by the
presence of a carina or suture, in short, without a prepectus; second and third ter-
gites fused as is evidenced by the apparent second tergite having two pairs of spira
cles.

Found in willow galls; parasitic on some hairy caterpillars, cot-
tony maple scale, etc.

Neopius carinaticeps Gahan has been reared from Agromyza
mines in Hordeum. Ofius (Eutrichopsis) dinidiatus Ashm. is a
parasite of Agromyza pusilla, and O. foveolatus Ashm. parasitizes

Pegomyia.

166 SEVENTEENTH Report STATE ENtToMoLocist or MInNEsoTA—1918

Minnesota species: Protapanteles sp. reared from Agresthia alter-
natella by S. Marcovitch. Also taken Sept. 15 at Lanesboro. A large
number of Apanteles were reared in our insectary in the 80’s and
are in the collection, but without labels to indicate the locality of collect-
ing. Specimens, however, were taken by Viereck at Lanesboro, Sept. 15,
1913. Atanycolus is found here (taken Sept. 11 in Rock Co. on sun-
flower) as are also the genera Habrobracon, Iphiaulax (Monogono-
gastra), Microbracon (Fillmore Co. in Sept.), Cardiochiles, Mirax
and Opius, representatives of the latter genus being taken in Itasca Co.,

Sept. 1, 1913.

Fig. 42. Aleiodes abdoniinalis Cress.: female. Family Braconidae.

MEN GSIOUD IND:

Second and third tergites fused as is evidenced by the apparent second segment
having two pairs of spiracles. Cutting edge of mandibles turned outward, their tips
neither meeting nor overlapping when they are flexed toward the mouth; mesothorax
with its sternum and pleurae, or at least the latter not divided into an anterior and
posterior portion by the presence of a carina or suture, in short without a prepectus.

This family contains parasites on various injurious forms, the
cabbage maggot, horn fly, wheat louse, etc. Dipterous larvae appear
to be its choice.

Coelinidea ferruginea Gahan, is a parasite of Meromyza ameri-
cana. Mesocrina pegomyiae was reared from P. brassicae and orig-
inally described from Minnesota by Brues. The same is true of
Aphaereta pegomyiae Brues, also reared from P. brassicae in our lab-
oratory. Specimens of Phaenocarpa were taken Aug. 14 at Duluth;
Ischmocarpa specimens were captured Sept. 3 in Itasca Co., and rep-
resentatives of Dacmusa were taken in Roseau Co., Aug. 19. Aspilota
has been taken in Fillmore Co., and Anisocyrta in Roseau Co.

Tue HyMENopPTERA OF MINNESOTA 167

STEPHANIDAE

Second and third tergites not fused. All known forms winged. Wings with a
distinct costal cell, i. e., with four cells running to base of wings. Frontal line longer
than clypeo-antennal line, or antennae inserted below middle of face; second divi-
sion of dorsum of abdomen with
only one pair of spiracles; pro-
podeum hardly extending be-
yond base of coxae, upper edge
of hind coxal sockets or coxal
line close to lower edge of ab-
dominal soeket or abdominal
line; mesothorax as in Alysii-
dae.

All rare insects; but lit-
tle known of their habits.
Ashmead says (Proc. U.
Sy Nats Muss) Volk Xue:
149) “The cephalic and
venational characters of
this curious group recall
those to be found in the
family Oryssidae, and I
can not help but think the
two families, in ages past,

had a common ancestry.”

Fig. 48. Chelonus sericeus Say, a Braconid.

BANCHIDAE

Second and third tergites not fused. Wings without a distinct costal cell, ie.,
with but three cells running to base of wing. Spiracles of first and second dorsal
segments in or before middle. Fore wings with two recurrent veins, the first repre-
sented by the cubito discoidal vein, first abscissa of cubitus wanting; frontal line
shorter than clypeo-antennal line; second division of dorsum of abdomen and propo-
dem as in Stephanidae.

The genus Banchus is represented in Minnesota.

BRACONIDAE

Fore wings with one or two recurrent veins: edges of fused second and third
dorsal abdominal segments may or may not meet beneath. First abscissa of cubitus
wanting or present. Caterpillars are often found more or less covered by tiny white
cocoons of Braconid parasites, the adult larvae having left the cocoons of their host
and spun their cocoons on the surface of the body of their dying victim.

Several hundred species are known to occur in this family, for the
most part highly colored. The larvae are parasitic in (rarely on) the
bodies of larvae or of pupae of other insects. They have also been
reared from the imagoes. One species is known to attack ants (there
are but few Hymenopterous parasites on Formicids.) Of insect in-
ternal parasites, it may be said that the victim is not eaten, the parasite

feeding on the lymph within the body either by means of its mouth or

168 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

by endosmosis. The host shows no sign of sickness at first, and

eats voraciously. But generally, when the period arrives at which
normally the larva would change to a pupa, the host sickens and
dies.

Vig. 44. Brachistes, sp., femaie. Bred Fig. 45. Brachistes, sp., male. <A
from borers ir poplar. Braconid.

To indicate the fecundity of these insects, and by inference,
their usefulness, we might cite the case of Microgaster. As many
as 1,200 specimens of
this genus have been
raised irom, a) -simele
Lepidopterous larva.

The following are
found in Minnesota:
(Blacus) Eubadizon
gracilis Brues, Ichneuti-
dea secunda Roh., reared
from larvae of the Purs-
lane Sawfly by S. Mar-
covitch, also taken in
Rock Co;, Sept. 9. sve
crodus simillimus Cress,

Chelonus sericeus Say,
\ (Chelonus, sp. Sept. 10
Fig. 46. Meteorus, sp. in Rock ConiGwelees

THe HyMeENoptrera OF MINNESOTA 169

tus Cress., Ascogaster rufipes Prov., Schioprymnus texanus Cress.,
Urosigalphus robustus Ashm., Earimus limitaris Say, Aleiodes ab-
dominalis Cress. and the genera Microtypus, Meteorus, (St. Louis
Co., Aug. 13), Orgilus, Brachistes and Heterospilus. An unidentified
Aleiodes was captured in Roseau Co., Aug. 19, and Macrocentrus, sp.
taken near Duluth, Aug. 14, and Blacus, sp. Sept. 1, at Itasca Park.
Triaspis was found in Rock Co. in Sept.

CAPERONIED Ags

Abdomen inserted high up on _ pro-
podeum, in middle or above middle of
latter; upper edge of hind coxal sockets
or coxal line remote from lower edge
of abdominal sockets or abdominal line.
Mesothorax with its sternum and its
pleurae, or at least the latter, more or
less divided into an anterior and pos-
terior portion by the presence of a
carina or suture, in other words with a
prepectus as indicated by Snodgrass.
Second and third tergites as in Alysii-
dae.

Only one genus, Capitonius,
found in the United States. See
Rohwer’s key to the species,
Canadian Entomologist, Vol.
DEEN ioe o kG:

Fig. 47. Capitonius ashineadi D. T.

C. ashmeadii D. T. found in Min-
nesota has been bred from Sterni-
dius alpha, living in the pith of
Rhus glabra.

EVANIIDAE

Abdomen inserted high up on propo-
deum in middle or above middle of latter,
upper edge of hind coxal sockets or coxal
line remote from lower edge of abdominal
socket or abdominal line. Abdomen al-
ways with more than two dorsal segments. _

Fig. 48. Hyptia harpyoides Bradley

The Evaniids are called by
Comstock, “ensign flies” because they carry the abdomen aloft like a
flag.

170 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

A striking peculiarity of the family is noted in the fact that the
abdomen is attached to the top of the metathorax, not to the posterior
end. The abdomen is compressed and has a very slender base.

Certain species in this group deposit their eggs in egg capsules of
cockroaches, and have been reared from them. They are met with
where cockroaches are abundant, and are reported to have been ob-
served on board ships, where, quite commonly, roaches are a pest.
Gasteruption incertum Cress., Odontaulocus abdominalis Cress., Hyp-
tia harpyoides Bradley, and the genus Aulacus occur in Minnesota.

TRIGONALIDAE

First abdominal segment broadened or bulbous at apex, not cylindrical. Costal
cell distinct.

A family of parasites living in nests of Polistes and Vespa and
preying upon the occupants.

Geo. W. Taylor reports (Can. Ent. XXX p. 14, 1898) taking nine
male Trigonalids in the vicinity of a large nest of Vespa occidentalis
in October. He says “The day was dull and the wasps sluggish, but
quite a number of males and perfect females were crawling about
around the entrance to the nest. Among the wasps were some speci-
mens of a conspicuous yellow and black Hymenopteron.”

These were identified as Trigonalys canadensis Hargm.

ICHNEUMONIDAE

As in Trigonalidae, but costal
cell obliterated by approximation
of costal and sub-costal veins.

Typical -parasites’ ‘of
many forms of insect life,
such as army worms, cut-
worms, and other injuri-
ous Lepadoptera. “As
parasites, however, their
attacks are by no means
limited to the butterflies
and moths, for they also
prey upon certain Coleop-
tera and Hymenoptera, as
well as on plant lice. The
larvae of Phryganids, al-

Fig. 49. Thyreodon brullei Vier.

THE HyMENOPTERA OF MINNESOTA 171

tho living in the water, do not escape them, and some species attack
spiders.

Generally, all have long slender bodies, ovipositors sometimes very
long and protected by a sheath. Eggs are laid either upon the outside
or within the caterpillar or other larva. When hatched, the Ichneu-
mon grub devours the fatty portions of its victim, the latter gradually

Fig. 50. The parasite, Lysiphlebus, sp.
attacking grain plant louse. From life.

growing weaker and dying about the time it would normally pupate.
The parasite lives largely by the absorption of the lymph and blood of
its host.

The genus Aphidius, an Ichneumon preying upon plant lice, is
extremely useful to the agriculturist. The species are all small.
Some prey upon aphids on oats, others on different forms of wheat
aphids. Usually a parasitized aphid is swollen and globular in
marked contrast to other non-parasitized aphids. The method of at-
tacking plant lice on the part of this genus is interesting; “the female
alights upon a leaf and runs about amongst the plant lice. When
she has selected one in which to oviposit, she stands with her head to-
ward it, and bending her abdomen under her thorax, between her legs,
she darts her ovipositor forward into the body of the aphid.” (Com-
stock). In this connection see the illustrations made in our labora-
tony, bes. 50. coleand 52.

172 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Another interesting form is Megarhyssa (Thalessa) and the genus
is exceedingly useful in destroying larvae of injurious borers belonging
to the family Siricidae. In order to reach these borers in the wood, the
ovipositor is of extreme length (six inches). It is bowed over the
back of the parasite, the tip being thus brought vertically down on the
wood, the latter is pierced or drilled and the egg laid in the burrow of
the borer. The injurious Tremex is the chief sufferer.

Fig. 51. <A grain plant louse, M. gran- Fie. 52 \
aria, in which the full grown parasi- :
tic larva can be seen.

“oreen bug’ killed by a
parasite.

Minnesota species: Thyreodon bruellei, var. transitionalis Vier.
T. morio Fab., Automalus quebecensis Proy. (see colored plate 1).
Ameloctonus fugitivus Say, A. clisiocampae Weed, Heteropelma flavi-
cornis Say, Exochilum fuscipennis Nort., E. tenuipes Nort., Eremoty-
lus macrurus L., Ophion slossonae Davis, O. bilineatus Say, O.
bifoveolatus Br., Enicospilus purgatus Say, Estochus laevis Cress.,
Anomalon lactatorius Fab. (Roseau Co., Aug. 19), Homotropus bi-
capillaris Walsh, Phaeogenes vincibilis Cress., P. discus Cress., Glypta
erratica Cress., Centetarus tuberculifrons Prov., Theronia allantae ful-
vescens Cress., [toplectis marginatus Prov., I. tenuicornis Cress. (Sept.
1, Itasca Park), Scambus indagator Walsh, S. monta Cress., Pimpli-
dea pedalis Cress., Odontomerus mellipes Say, Eremochila indagator
Walsh, Tromatobia scriptifrons Cress., Polysphincta lunata Cress.,
Lissonota frigida Cress., L. varia Cress., L. rufipes Cress., L. pleuralis
Cress., Bathycetes scutellaris Cress., Meniscus elegans Cress., Coleocen-
trus pettitu Cress., Cryptus americanus Cress., C. nuncius Say, C. per-
similis Cress., C. limatus Cress., Amblyteles calignosus Cress., A. brevi-
penmis Cress., A. instabilis Cress., A. insolens Cress., A. jucundus

THE HyMENOPTERA OF MINNESOTA 173

Brull., A. malacus Say, A. comes Cress., A. laetus Cress., A. rufiven-
iis, Brully “A -orpheus Cress., A. lewissi (Cress. A. \sublatus
Cress., A. acerbus Cress.,
A. cincticornis Cress., A.
questuosus Cress., A. brevi-
cinctor Say, A. amulipes
Cress., A. ventralis Cress.,
A. suturalis Say, A. laetus
Brulle, Pterocormus _ sp.
(see colored plate 2), Meg-
arhyssa atrator F., M.

lunatrix F., Ichneumon
canadensis Cress., I. irri-
tater Fs, 2i(Filimore: (Coe
Sept.. 15), °F... funestus
Cress., Trogus quebecensis
Prov. The following gen-
era also are represented in
our collection: Trioxys,
Lysiphlebus, Praon, Plec-
tiscus, (Aug. 4, St. Louis
Co., woodland, along lake shore), Porizon, Cremastus, Mesochorus
(Sept. 1, Itasca Co.), E-vetastes, Paniscus, Sagarites, Diodes, Anisitsia
(taken Aug. 28, Itasca Co.), Neonortonia, Promethes costalis Prov., has
been taken at Itasca Park in Aug. and Stoplictus marginatus Prov.
in Sept. Periope aethiops Cress., was found at Itasca Park the last

Fig. 538. Megarhyssa lunatrix Fab.

of August, sunning on asters; Polyblastus edalis Cress., Itasca Park,
Hoplesmenus morulus Say taken in Itasca Co. in Sept. The hosts of
the latter are Grapta and Euvanessa.

The following have also been taken in Minnesota by H. L. Viereck
in 1913: Exochilum sp. St. Anthony Park, Sept. Callisphialtes sp.
Roseau Co., Aug. 20. Paranomalon Martin Co., Sept. 13. Epiurus
Aug. 29 Itasca Co., flying and sunning. Paniscus, Sept. 15, Fillmore
Co. Iseropus, Sept. 1, Itasca Co. Lissonota Sept. 15, Fillmore Co.
Aphidius Sept. 1, Itasca Co. Conoblasta Aug. 28, Itasca Co. E-xoly-
tes Sept. 1, Itasca Co. Stilpnus Sept. 15, Fillmore Co. on Cardius ar-
vensis. Campoplex Aug. 29, Itasca Co. Phygadewon Aug. 16, St. Louis
Co. Cryptus Aug. 12, St. Louis Co. woodland. Hemiteles Aug. 16
St. Louis Co. woodland along creek. Anomalon Aug. 13, St. Louis
Co. woodland along lake shore. Pezomachus Aug. 14, St. Louis Co.
woodland. Herpestomus Aug. 28, Itasca Park.

174 SEVENTEENTH Report STATE ENtTomoLocist oF M1inNEsoTa—1918

Fig. 54. (Hremotylus) Allocamptus
macrurus Li. Fig. 55. Ophion bilineatus Say.

Exetastes sp.

OU
~

Fig. 58. Sigalphus cureculionis, parasite on plum curculio, male and female adults,
larva a, cocoon b, and pupa c; all much enlarged.—Report of New Jersey State Mu-
seum, 1909.

ICHNEUMONIDAE

THE HyMENOoPTERA OF MINNESOTA 175

Fig. 60. Anisitsia sp.

Fig. 59. Rhyssa sp.

Vig. 61. Trogus vulvinus on a but-
terfly chrysalis (Papilio) from which
it has just emerged —From Report of Fig. 62. Idechthis sp. Bred from Ephestia
New Jersey State Meseum 1909. kithniella.

ICHNEUMONIDAE

Entomotocist oF MinnNEesota—l918

SEVENTEENTH ReEporT STATE

176

‘YnoTOsuUOD jo RAioJdoUsTIAHY 9G, Wor y[—
‘BaplodIudAy 94} JO UOTIBUPA SUIM PUB dINjJONA}S SUT}PRAISNI[I ‘ssojnqau snydowsMid “EO “StA

en

\

Wie ey) Vey

THe HyMENOPTERA OF MINNESOTA We
NOMENCLATURE OF WING PARTS IN THE DRAWING OF

Diastrophus nebulosus

OLD SYSTEM COMSTOCK-NEEDHAM SYSTEM
Marginal cell SO ar ZiaGl IAP Ie,
Areolet Rats
CYNIPOIDEA

(Gall flies )

The members of this superfamily are, for the most part, typical
gall makers. The peculiar growths seen upon oak and various other
trees are largely the work of Cynipids; the different galls in oaks, par-
ticularly, are the work of members of this family. Some of these oak
galls are designated as follows: Fibrous oak apple, spongy oak apple,
larger empty oak apple, smaller empty oak apple, bullet gall, giant oak
gall. On the blackberry also we have the pithy blackberry gall, and in
the rose, the mossy rose gall. Lack of space forbids a detailed descrip-
tion of these galls.

The group may be subdivided into three divisions. (a) True gall
flies, whose eggs are laid in plant tissue and whose early stages are
passed within galls, Cynipidae. (b) Iniquilines or guest flies; these
may be referred to as tenants or dwellers in another man’s property ;
and (c) Parasites, living in the interior of the bodies of other living
insects, chiefly aphids or the larva of Diptera. This latter division is
represented by the family Figitidae.

Guest gall flies resemble closely the true makers of the galls, and
Kellogg states conjecturally that the guest species may be a degen-
erate, loafing scion of the working stock.

Over 200 years ago, Malphigi advanced the theory that these galls
were caused by the injection of a fluid into the plant. Previous to this,
it was supposed that the galls were a purely vegetable production and
that the maggots found therein were due to spontaneous generation.
Reamur came to the conclusion that Malphigi’s views were in part er-
roneous and that the gall was not due to any fluid but to irritation
of tissue when stung, and by the presence of the egg.

Later studies of the ecology of these insects, while still leaving
much to be learned, indicate that the mere presence of the eggs or
the injection of fluid by the parent do not necessarily of themselves

178 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESoTA—1918

produce galls; but that probably gall growths are due in part at least
to reactions between physiological processes of the plant tissue and the
growing larva, which may absorb the sap at that particular part of
the plant.

Amongst gall flies, we find the occurrence of parthenogenesis dur-
ing the summer; in fact, in many species the males have never been
discovered. Out of many thousand galls of Cynips districtra and C.
folii (28,000 or more) about 14,000 flies were raised; but all females.
The fact has been thoroly established that in many of these in-
sects we have an alteration of generations, one of the two being par-
thenogenetic ; individuals of one generation are like their grandparents,
not their parents.

Packard says in this connection, “When we see a single oak hung
with countless galls, the work of a single species, and learn how
numerous are its natural enemies, it becomes evident that the demands
for a great numerical increase must be met by extraordinary means
like the generations of the summer broods of Plant Lice.”

Referring again to the guest gall flies also found in galls, it may
be said that frequently they resemble very closely the fly that makes
the gall. In this connection, it may be stated that from a single species
of gall, as many as 30 different kinds of insects (largely guest gall
flies) have been obtained.

Gall flies appear to be closely allied to the Chalcids and resemble
them strikingly. Their bodies are flea-like; trochanters usually com-

posed of a single joint; wings usually with a characteristic venation.
See ice 63:

FIGITIDAE

Dorsal abdominal segments extending down along the sides and meeting beneath,
enclosing or concealing the ventral segments or all the ventral segments except a part
of the apical one.

One species in this family is parasitic on the cabbage louse.
Pseudocoelus gilletii Ashm. has been reared in Minnesota from
puparia of Pegomyia brassicae. This is a most extensive family, well
represented in North America. Without exception, as far as known,
the species are all parasitic, principally upon larvae of Diptera, tho
some prey upon aphids ard one is known to attack the larva of the
lace-winged fly.

THE HyMENopPTERA OF MINNESOTA 179

CY NIBIDAE

Dorsal abdominal segments not extending down the sides (as in Figitidae) so as
to meet beneath ventral segments. All or nearly all the ventral segments visible.
Basal joint of hind tarsi usually shorter and never much longer than joints two to
five united. Abdomen not at all or very little longer than head and thorax combined.

The true gall makers, affect oaks particularly. The amateur
may well ask the question: “Why do galls take different shapes”; for
it is a fact that “each spe-
cies of gall insect infests a
special part of one or more
particular species of plant,
and the gall made by each
species of insect is of a
definite form.” Cook, who
has done much work on
the Cynipidae believes that
the morphological charac-
ter of the gall depends upon
the insect producing it,
rather than upon the plant
upon which it is produced ;

Vig. 64. (Rhodites) Diplolepsis rosae L. and es as = Be
side view of head, thorax, and abdomen. for example, galls Be

duced by insects of a par-
ticular genus show great similarity of structure even tho on plants
widely separated, while galls on a particular genus of plants produced
by insects of different genera, show great differences.

The larval gall fly reaches its full development coincidentally with
the full growth, or end of the vitality of the gall. On deciduous leaves,
the vitality of the gall is shortest, ending in autumn; twig galls may
retain their vitality all winter, or even through a second winter. The
insect pupates in the dead protecting gall.

In these galls, as stated, one finds not only the gall makers, but
frequently guests or parasites. Both of these groups (commensals or
parasites) may themselves belong to the Cynipidae. On the other
hand, the parasites may be Braconids or Chalcids or Ichneumonids,
while the boarders may be beetles or lepidopterous caterpillars.

Cynips confluens Harris, is the maker of a gall known as the oak
apple or may apple, found on the leaves of the red oak. These galls
are sometimes two inches in diameter, green, pulpy at first, but later
acquiring a hard shell with a spongy interior in the center of which is
a woody kernel containing larva or pupa.

180 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

This group offers a most interesting and inviting field for the
student and collector and much remains to be learned regarding it.
Galls should be collected early in the autumn, separated as to kind and
enclosed in muslin bags.

(Rhodites) Diplolepsis rosae L. occurs in the Lugger collection,
with many other unnamed galls. We are indebted to Prof. O. W.
Oestlund of the state University for the following list of Cynipid galls,
collected in this state and now in the University collection.

Biorhiza forticornis Walsh, Oak Fig Gall. Cass Lake, Sept. 10.
Neuroterus batatus Bassett, Oak Potato Gall, Manitou Junction, Oct.
15. Dryophanta lanata Gill, Excelsior, Oct. 1. Holcaspis globulus
Fitch, Oak Bullet Gall, Minneapolis, Oct. 5. Cynips confluens Harr.,
Oak Apple, Burntside Lake, Aug. 17. Amphibolips inanis Osten
Sacken, Empty Oak Gall, Duluth, Sept. 12. Andricus petiolicola Bas-
sett, Oak Petiole Gall, Minneapolis. Andricus frondosus Bassett, Mani-
tou Junction, Oct. 15. Andricus seminator Harr., Oak Seed Gall,
Minneapolis. hodites bicolor Harr., Spiny Rose Gall, Minneapolis.
Rhodites multispinosus Gill. Large Spiny Rose Gall, Cass Lake, Sept.
10. Rhodites globulus Beutenmiller, Globular Rose Gall, Granite
Paliss@ct- l"Cass ake: sept. 10:

IBALIUD AT

Same as Cynipidae, but basal joint of hind tarsi at least twice as long as second,
third, fourth and fifth joints united. Second, third and fourth joints of tarsi longer
than fifth; abdomen very distinctly compressed from side to side and distinctly longer
than head and thorax united.

This family represents a small group of parasites. W. H. Har-
rington states that /balia maculipennis destroys the larvae of Tremex
columba and Xiphydria albicornis. In the Riley collection is a sin-
gle specimen of the above insect labelled “So. Ill. bred from Hickory
wood June 4, 1875.” Probably, therefore the group attacks, gen-
erally, members of the superfamily Siricoidea.

CHALCIDOIDEA

First abdominal segment not forming a scale or knot (petiole) and therefore not
strongly differentiated from the remaining segments. Usually small insects, less than

9

3 millimeters in length and metallic.

All species in this superfamily with few exceptions (Isosoma for
example) are parasitic. The insects are small and noted for their bril-
liant colors and striking forms. Dr. L. O. Howard of Washington,
D. C., was the first entomologist in America to work on this group,
and he and the late Mr. Ashmead applied themselves, practically

THE HyMENOPTERA OF MINNESOTA 181

NOMENCLATURE OF WING PARTS IN THE DRAWING OF

Phasgonophora sulcata

OLDISVSiEM COMSTOCK-NEEDHAM SYSTEM
Submarginal vein Sc+R+M
Marginal vein Scaigka ist abscissaonm pant)
Postmarginal vein Scapa (2daabscissasone pane)
Stigmal vein. r (radial cross vein)

fig Su oF 1g SUE tit SOME gogcles

f -- Mb iy some soedres

Fig. 65. P. sulcata, showing typical structure of a Chalcid.—From The Hymenoptera
of Connecticut.

182 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOoTA—1918

alone in the field for many years, to systematic and ecological work
in this suborder. As far back as 1867, Kirchner listed 2,407 Euro-
pean species, and more than 4,000 species have been described.
There are probably more than 1,000 species in the group in
North America and a large field is still open for investigation as to
species both in Europe and North and South America.

The group exhibits great variety in methods of parasitism; a large
number live in galls, feeding on the gall makers themselves or guest
insects frequenting the galls; others attack caterpillars; some feed only
on pupae; others prey upon bees; some on scale insects and aphids,

PIC IOLMTI

1 FrKQO0OCLIT
ie

>
LOIET LTT

LOM? LMI

) el qohLr 7

lig. 66. Thorax of Syntomaspis, typical of the Chalcidoidea.—F rom The Hymenoptera
of Connecticut.

and others are found in the egg-case of cockroaches. One European
species is parasitic on the common housefly. Other species prey upon
the larvae of the Hessian fly. It is evident that this group is of the
greatest economic importance. Illustrative of this fact is the condi-
tion sometimes prevailing in the south, where in a certain year, 95 per
cent of the eggs of the destructive cotton caterpillar were killed by a
chalcid parasite.

As evidence of the work of one chalcid, we may cite the case of
Leucospis gigas, the female of which pierces the masonry-like hard-
ened mud walls of an European mason bee. By patient work, the

THe HYMENOPTERA OF MINNESOTA 183

hard, stone-like wall is punctured by means of the ovipostor of this par-
asite and an egg introduced. Fabre has observed that one bee cell may
be visited at least four times by a parasite, four eggs being deposited in
a cell where there is only food supply for one larva. This, says Fabre,
appears to illustrate a deficiency in instinct, for the parasite first

hatched apparently destroys the eggs of its brothers and sisters.

Even a brief account of this group would not be complete with-
out reference to the pollenization or caprification of the Smyrna Fig
by a Chalcid. Caprification, as practised in Italy and the Grecian
Archipelago, is a remnant of an old custom based upon the belief that
figs would not develop unless so treated. It consists in making use
of a chalcid, Blastophaga grossorum (and possibly other species),
which infects wild figs. Branches of the wild fig are suspended
amongst branches of cultivated varieties; the fruit on the latter is
entered by the female insect and thus pollenization secured, altho
she does not lay her eggs in the fruit of cultivated varieties.

This time-honored custom is probably not necessary, for figs ripen
in parts of the world where this is not practised, tho Kellogg states
that this process has really added the Smyrna Fig to California’s
fruit list.

MYMARIDAE

Hind wings linear, pedunculate at base, ovipositor usually issuing just in front
of tip of abdomen. Antennae in female most frequently terminating in a distinct fusi-
form or egg-shaped solid club, more rarely in a two-jointed club.

Wings of members of this family are minute, slender, destitute
of nerves, fringed with long delicate hairs and stalked at the base.
Perhaps the most striking fact about the group is that two species are
found in water, one form swimming by means of its wings.

One species is parasitic on scale insects and another has been bred
from eggs of the plum curculio.

Here occurs Alaptus excisus West., said to be the smallest known
insect. Westwood gives the following measurements: length 1/6 mil.
or 1/150 of aninch. This, however, is probably A. pesculus Hal. and
is about % mil. long. Other insects may be smaller; a certain beetle
for example is %4 mil. long.

184 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Halliday, in speaking of this group (Ent. Mag. Vol. I p. 342)
says: “This tribe comprises the very atoms of the order Hymenop-
tera. Their hues are mostly black or yellowish, unadorned by metallic
splendor; the plumed and iridescent wings of many are beautiful ob-
jects for the microscope. . . . The females oviposit in the eggs of
other insects, from which the tiny parasite emerges only in the per-
fect state, a single butterfly’s egg often nourishing the transformation
of many individuals.”

Polynema consobrinus Gir. has been bred from Anthonomus signa-
tus by S. Marcovitch in our Insectary (16th Rep. State Ent. Minn.
1916) and Mr. Marcovitch has also reared Anaphoidea conotracheli
Gir. from the eggs of the purslane sawfly. Girault reports an egg
parasite of the codling moth from this family.

TRICHOGRAMMIDAE

Tarsi three jointed and antennae elbowed with few joints, at most 9-jointed;
pubescence of wings arranged linearly.

Species have been raised from the Buffalo treehopper. Others
are parasitic on the more common butterflies. In Minnesota, Apros-
toctus whitmani Gir. has been reared from the eggs of the sunflower
tortoise beetle Physonata unipuncta Say, and we also have in the state
Chaetostricha pretiosa Riley.

EXPLANATION OF COLORED PLATE 2.

8. Hucerceris zonata Cress.

9. Microbembex monodonta Say.

10. Crabro sexmaculatus-Solenius (Xestocrabro) Sayi Ckll.
11. Halictus (Agapostemon) virescens F. female.

12. Halictus (Agapostemon) virescens male.

13. Triepeolus bardus Cress.

14. Amblyteles (Pterocormus?) longulus Cress.

15. Chlorion (Ammobia) ichneumon L.

1. L. WOOD, DEL. BUR. ENGRAVING, MPI

MINNESOTA HYMENOPTERA

Plate 2.

THe HyMENOPTERA OF MINNESOTA 185

TEDTRASTIGCRIDAL

Sub-marginal vein with from one to five bristles; post-marginal vein usually
absent. Scutel with four bristles, all behind the middle; abdomen sessile; hind tibiae
with one spur; male antennae simple.

Fig. 67. Tetrastichus sp., bred
from clover heads.

Tetrastichus esurus Riley, is a parasite of the cotton worm. Many
specimens have been bred from oak galls, and the genus Tetrastichus
is a well-known parasite of the Hessian fly. T. racemariae Ashm.,
occurs in Minnesota.

ENTEDONTIDAE

Sub-marginal vein either ornate or provided with two bristles; scutel with two
bristles near the middle. Hind tibiae and male antennae as in Tetrastichidae.

An interesting family of parasites, its members attacking the
mourning cloak butterfly, the peach lecanium, the white-marked tus-
sock moth, and other injurious insects. The greater number of species
appear to have been bred from leaf miners and particularly from the
trumpet leaf miner of the apple, Tischeria malif oliella.

In Minnesota, Mr. Marcovitch has reared Secodella argyrestheae
Crawford from Argyresthia alternatella; also Achrysocharisk ansensis
Gir. from eggs of the purslane sawfly.

186 SEVENTEENTH Report STATE ENtToMoLocist oF MINNESOTA—1918

EULOPHIDAE

Abdomen sessile or with a distinct petiole that is transverse and smooth. Hind
coxae normal; post-niarginal and stigmal veins rather long; antennae often flabel-
late in male.

One species in this family is parasitic on the tussock moth; others
are parasitic on leaf miners and some borers; others on grain plant
lice; one on the Hessian fly; and another attacks the fruit bark-beetle ;
another is a parasite on the woolly louse of the apple; others on oyster-
shell scale and other scales including the San Jose scale.

ELASMIDAE

Abdomen as in Eulophidae; hind coxae very large and strongly compressed; head
semi-globose, front deeply, sparsely punctate; antennae flabellate in male.

These beneficial parasites (Elasmus) have been reared from vari-
ous leaf mining caterpillars.

Elasmus has also been bred from microgasterid cocoons and from
other insects.

ELACHERTIDAE

Abdomen usually with a distinct petiole, antennae inserted below middle of face,
simple in male. Sub-marginal vein entire. Hind tibiae sometimes with two spurs.

Parasites on pomace fly, horn fly, wheat plant louse, cabbage
plant louse, Hessian fly, apple curculio, joint worm, cabbage butterfly,
grain weevil, angoumois grain moth, strawberry weevil, etc. The
eggs of one species are laid within the eggs of the tent caterpillar moth,
and they have been reared by the thousands from the American tent
caterpillar.

PTEROMALIDAE

Antennae elbowed, thirteen-jointed with two ring joints and three joints to the
club; seape large and long; occipital line incomplete. Head most frequently trans-
verse or subquadrate. Mandibles usually stout, three or four dentate at apex. Ovi-
positor issuing far anterior to tip of abdomen.

Members of this family parasitise Hessian flies, joint worms,
wheat lice, cabbage plant lice and other aphids, tent and other cater-
pillars, strawberry weevils, cabbage butterflies, grain weevils, white

THe HyMenortera or MINNESOTA 187

pine weevils and various other insects. They also breed in Pimpla and
many other primary parasites.

S. Marcovitch has bred Habrocytus obscuripes Ashm., and Cato-
laccus perdubius Gir. in the Minnesota insectary, from the strawberry
weevil. (16th Rep. State Ent. Minn. 1916).

§
4
4

L Fig. 70. Collopisthia nematicida Pack, parasite of larch
Fig. 69. Pteromalus puparum. sawfly.—F'rom a colored drawing.

SPALANGIIDAE

Antennae 12-jointed. Abdomen distinctly petiolate. First tarsal joint not swol-
len.

The minute Spalangia muscae has been bred from Stomoxrys pupae.
The same species is known to attack the pupae of both the horn fly
and the house fly. Parasitism by this species always takes place in the
pupal stage of the host. In a collection of Stomoxys pupae made in
Texas, it was found that 40 per cent were parasitized by this insect. S.
hirta Haliday, confined with horn fly pupae promptly attacked the latter.

S. lanaiensis Ashm. has been reared from dipterous pupae. The
latter two species are evidently important enemies of the horn fly.

TRIDYMIDAE

Abdomen almost sessile. Antennae 12-jointed; pronotum scarcely visible in the
middle; funicle of antennae 5-jointed.

Hemadas nubilipennis Ashm. has been reared from galls on
huckleberry made by Solenozopheria vaccini Ashm.

188 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESoTA—1918

APHELINIDAE

Antennae §-jointed; notauli distinct ; middle tibial spur moderately long; meso-
sternal pleurae distinct.

This large and useful family of parasites attacks many of the
scale insects, among others, the San Jose scale, the Lecaniums, the
cottony maple scale, the woolly aphis of the apple, cabbage aphis,
and many other injurious forms.

Aphelinus fuscipennis How., and A. mytilaspides both.attack the
San Jose scale in California, the first named being quite abundant.

ENCYRTIDAE

Antennae 11-jointed, elbowed, scape large and rather long; pronotum small, fre-
quently not visible in the middle. Second pair of legs long, saltatorial with a very
long tibial spur. Hind wings never narrow, nor linear; ovipositor issuing far an-
terior to tip of abdomen.

Parasitic on oys-
ter-shell scale, rose
scale, maple “seale
joint worm, Hessian
fly, ladybird beetles.
Bred from puparia of
syrphid flies; found
in caterpillars of vari-
ous moths and butter-

flies. Species have

y been bred from cab-
bage lice, from bag
Vig. 71. Copidosoma gelechiae Howard. Feared from gall bata ungeeite JOU e
on golden rod. in the egg sacks of
spiders. They are also
parasitic on eggs of certain species of butterflies, and on mealy bugs.
(Timberlake Univ. of Calif. Bull. March 28, 1918.)
Aphycus pulvinariae How. is a parasite of the maple scale and
A. bruneus How., a parasite of the rose scale. A. flavus attacks the
European fruit Lecanium in California. Chiloneurus dactylopii How.
and Encyrtus inquisitor How. probably occur in all greenhouses where
their host, Pseudococcus citri, is found. Encyrtes (Aphidencyrtes)
aphidiphagus Ashm. attacks the cabbage aphis. Copidosoma gelechiae
How. occurs in Minnesota, its host being Grorimoschema gallae-solida-
ginis.

Tue Hymenoptera oF MINNESOTA 189

SIGNIPHORIDAE

Antennae 6-jointed; marginal vein about as long as subcostal vein. Second pair
of legs long, saltatorial with a very long tibial spur. Vronotum small, frequently not
visible in the middle.

Signiphora flavopalliata Ashm. is parasitic on Lepidosaphes becku;
and S. occidentalis How. has been reared from the red scale.

EUPELMIDAE

Pronotum small, frequently not visible in the middle. Second pair of legs as in
the two preceding families. Antennae 13-jointed ; occipital margin of vertex rounded.

Eupelmus allyni French is an important parasite of Mayetiola
destructor; E. reduvii How. has for its host the common squash bug.
Eupelmus coleopterophagus Gir. has been reared, in Minnesota, from
the strawberry weevil by S. Marcovitch (16th Rep. State Ent. Minn.
1916). The female of Eupelmus mirabilis, a species bred by C. V.
Riley from the eggs of the angular-winged katydid, and from the
eggs of a large sphinx moth, is able to roll itself up into a more or less
compact ball. See Riley’s excellent illustration, Fig. 48, p. 162, 6th
Mo. Report where he refers to the species under the name of Anti-
gaster mirabilis, as “The back-rolling wonder.”

CALLIMOMIDAE

Thorax not strongly developed, pronotum large; antennae many jointed, elbowed;
body metallic, sides of scutel curved, abdomen frequently compressed; if without an
extended ovipositor, the abdomen is conical or conic-ovate; ovipositor far anterior
to tip of abdomen. Fore tibiae armed with a large curved spur,

Specimens of the Genus Ornyrus have been bred from cynipid
galls and from [Rhodites. Diomorus gabriskei Cress. is parasitic in
nests of Ceratina dupla. Oligosthenus stigma F. has been reared from
Rhodites rosae and Syntemaspis druparum Boh. from apple seeds.
Megastigmus nigrovariegastus Ashm. has been bred from seeds of

Rosa rugosa.

EURYTOMIDAE

Mandibles not strong, mostly 4-dentate at apex. Thorax as in preceding family.
Antennae many jointed, with ring joints, rarely without; scape large and rather
long; body not metallic; sides of scutel almost straight; anterior tibial spur large
and strong, middle tibial spur small and weak, hind tibiae with two apical spurs.
Ovipositor far in advance of tip of the abdomen.

Members of this family are markedly parasitic. Species have been
reared from the eggs of tree cricket, from the fruit bark beetle, and
many other forms. There are, however, in the group, a few species

190 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

which are not parasites. Brucophagus funebris, for example, is the
well-known clover-seed chalcid, very destructive to seed of clover and
alfalfa; and of the genus /sosoma, I. tritici and I. hordei called “joint
worms,” live in grain or grasses. Here occur both winged and wing-

The clover seed Chalcid, Brucophagus funebris after Urbahns, U. S. Bureau
Ent. a imago, b larva, ec pupa.

e.
gg
“1
to

less females. These insects produce galls on wheat stems, checking the
growth of the plant and causing the leaves to yellow. One or more
gall-like swellings of the stem of grains or grasses denote the presence
of the larva. Straw should be used up completely during the winter,
for the adult insects emerge from infested stems in the spring.

I. tritici and I. grande were supposed to be two distinct species,
but it has been demonstrated by Riley that there is here, really, an alter-
nation of generations of one species. Both generations may be wholly
or in part parthenogenetic. Eurytoma pissodis, described by Girault
in Bull. Brooklyn Ent. Soc. is parasitic on the white pine weevil.

THe HyMenorrera or MINNESOTA 191

Macrorileya oecanthi Ashm. has been reared from the eggs of the
snowy tree cricket. Eurytoma crassineura Ashm. is parasitic on
Scolytids. Evoxysoma vitis Saunders, has been reared from grape
seeds. Eurytoma gigantea Walsh has been reared in Minnesota by S.
Marcovitch from goldenrod gall. EF. juniperinus Marcovitch was
reared from deformed berries of Juniperus virginiana L. Oct. 13. (Ann.

Gi >
| i Hl

Vi i

| | i \

hall

Vig. 73. Isosoma tritici, a, b larva, f female, g fore wing TT Uf |
h, hind wing.—The Insects of New Jersey, 1909. 7 i
Ap \X\ \

Am. Ent. Soc. 8 pp. 166-168). Bruchopha-
gus funebris How. the clover seed chalcis is
common in Minnesota, destroying the seeds

of crimson clover and alfalfa.

( Anna

Wig. 74. Female Jsoso:
ma oOvipositing in
stem of wheat.—In-
sects of New Jersey,
1909.

PERILAMPIDAE

Antennae elbowed, fore tibiae armed with a large curved spur; hind femora not
greatly enlarged; thorax strongly developed, much arched and deeply punctate; stig-
mal vein developed; abdominal segments visible.

Perilampus hyalinus Say occurs in Minnesota (see colored plate
1). Reported as parasitic on the pine saw fly. It is also a second-
ary parasite on Amelectonus fugitivus Say. Ashmead has reared
Perilampus sp. from Chrysopa cocoons.

192 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESoTA—1918

RUCHARIDAE

Same as Perilampidae, but stigmal vein not developed, and second abdominal seg-
ment very large, inclosing other segments. Ovipositor well forward,

In members of this
family, the structure of
the thorax, particularly
of the scutellum, is most
curiously modified. This
modification with the
brillant metallic blue
and -green colorme
which characterizes the
members of the family,
make it perhaps the

most striking group of

Vig. 75. Pseudometegia sp. dorsal and side view. the superfamily. Some,

or all, attack ants and

are particularly abundant in tropical countries where ants abound.
Fig. 75 illustrates a species found in Minnesota.

CHAECIDIDAE

Antennae elbowed and with f
one, two or three ring joints, i
very rarely without ring joints;
tarsi 4 or 5-jointed, fore tibiae
armed with a large curved spur,
hind tibiae with two apical
spurs; hind femora much _ swol-
len; fore wings never folded ; ovi-
positor rarely prominent, not
curved over dorsum of abdomen.
Abdomen most frequently con-
ical or conie ovate, more rarely
globose or oblong.

Strongly typical of the
suborder and _ containing
a large number of useful
parasites: At least:vone
species is a secondary para-

site on parasites working

Fig. 76. Phasgonophora sulceata Westw.

on Lepidoptera larvae.

The minute and interesting chalcid Podagrion (Palmon) pachy-
menes is said to shelter itself under the wings of a species of Mantis

THe HyMeENopTerA OF MINNESOTA 193

in order to be in favorable position to oviposit in the eggs of the latter
when it is forming its peculiar egg case or ootheca.

Spilochalcis mariae Riley parasitizes our larger moths, Telea,
Samia ete. S. debilis
Say is a secondary
parasite of Hemero-
campa leucostigma ;
its hosts are Amor-
phota orgyiae, Mete-
orus communis, M.,
hyphrantiae, Prota-
panteles hyphantrae,
P. delicatus. Chalcis
compsilurae Crawf.,
has been reared from
me | _. puparia of Compsi-

Fig. 77. Polyneina striaticorne Gir. lura concinnata.
Minnesota species:
Phasgonophora sulcata Westw., Polynema_ striaticorne Gir. Spilo-
chalcis sp.

LEUCOSPIDAE

As in Chaleididae, but fore wings when at rest folded longitudinally, and oviposi-
tor is curved over dorsum of abdomen.

In Minnesota Leucospis affinis Say has been bred from the nests
of a leaf-cutting bee.

NOMENCLATURE OF WING PARTS IN THE DRAWING OF

Serphus caudatus

OLD SYSTEM COMSTOCK-NEEDHAM SYSTEM
Veins Veins
Basal M and m-cu ,
Cubital Media and at wing margin R,4+,+M,
Transverse Cubital R; and r-m
Recurrent Mst4
Cells Cells
First submarginal Ist R,+R

Fused cells beyond Ist submarginal Rststs
Marginal (reduced to a minute area
beyond the stigma) Zd Ra eR:

194 SEVENTEENTH Reporr State ENToMoLoGIsSt oF MINNESOTA—1918

\

Cabiraton Or
cens beyond
SZ SMTAGIAG/

a _—~
, a — — —_—=—

Fig. 78. Serphus caudatus, structure typical of the Serphoids.—From the Hymen-
optera of Conn.

THe HyMenorpTera oF MINNESOTA 195

SERPHOIDEA
( Proctotrypoidea )

Abdominal segments not strongly differentiated as petiole and gaster; wings
usually well developed, sometimes vestigial or lost; body not flea-like; wings usually
without veins, or with only sub-costa and part of radius present. Slender insects
mostly small. ,

Many of these are egg parasites transforming within the eggs of
their victims, largely butterflies, moths and Hemiptera. Species very
minute, hardly to be seen with the naked eye, extremely active and of
brown or black coloration. They may be obtained by sweeping, with a
net, grass and other herbage. Some of the species lay their eggs in the
larvae of various wheat flies. The larva of one genus (Gonatopes)
has been found fastened under the wings of leaf hoppers. Some spe-
cies have been reared from larvae or galls of small Dipterous midges,
some from cynipid galls, some from ants’ nests, and some are known to
attack Coleoptera.

PEG AS RD AE:

Trochanters with two joints, or stigma very short and broad; antennae inserted
below middle of face at junction of clypeus with face; wings wanting in most spe-
cies; abdomen with sides acute or margined; labial palpi with one joint; abdomen
sessile or sub-sessile.

One species of this family oviposits in the eggs of the spring
canker worm and helps to keep it in check. Another is an egg para-
site of the Hessian fly, and
it is claimed that from a
single egg of the parasite,
there may develop several
of the adult insects. Mem-
bers of the family exhibit
a wide choice of victims.
Species are known to at-
tack a Cecidomyid, feeding
on walnut, a blackberry gall
midge, a nut weevil, the
Fig. 79. Platygaster herrickiim—From Proce. U.S. Carolina locust and other

INEM DER: NCD ie Daas locustids, the squash bug,

tree crickets, the harlequin

cabbage bug, the fall web worm, tent and other caterpillars, the tus-

sock moth, tabanids, clover flower midge. Leptacis sp. taken by H.
L. V. in Fillmore County, September 15.

196 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

SCELIONIDAE

As in the preceding family, but labial palp has two or more joints. Antennae
with twelve, eleven or seven joints. Abdomen generally carinated.

Parasitic on locusts, tree crickets

and various bugs and caterpillars.

( ( Specimens have been bred from

the corn worm, from the eggs of

the tussock moth and eggs of Dip-
tera.

Scelio luggeri (Riley) Ashm.
occurs 1n Minnesota, parasitic on
the eggs of Caloptenus. The genus
Telenomus also occurs in the state
and doubtless many forms not evi-
denced in our collection.

Fig. 80. Telenomus sp.

CERAPHRONIDAE

Trochanters with two joints, or stigma very short and broad; antennae inserted
below middle of face; abdomen with sides rounded.
A Hessian fly parasite, Ceraphron des-
tructor, occurs in this family; also a
parasite on the cherry aphis. Lygocerus
niger How. is parasitic on grain plant
lice; Eumegaspilus erythrothorax Ashm.
is found in nests of Lasius. Measpilus
striatipes Ashm. has been bred from a

2 CERAPHRON—somne

Pegomyia puparium in our Insectary. Fig. 81. Ceraphron humatatus—
; U. S. Nat. Mus. Bull. 45.

DIAPRITIDAE

Wings present, sometimes absent; front wings never with a more or less dis-
tinct stigma; hind wings with no basal cell; labial palpi with two joints; antennae 12-
13- or 14-jointed, inserted on the middle of the face, usually on a frontal prominence ;
trochanters 2-jointed, or stigma very short and broad.

Bred from syrphus flies, wheat stem maggot, cabbage maggot
and other Diptera.

Entomacis ambigua Brues, is found in nests of Stemamma ful-
vumpiceum. Loxotropa pegomyae Brues has been bred from the cab-
bage maggot in Minnesota. Galesus sp. taken by H. L. V. at Itasca
Park Sept. 1. Diapria (Tropidopria) conica F. is a parasite of Eris-
talis tenax. For an account of the biology of this species see G. E.
Sanders Can. Ent. 43 (48-50) 1911.

THe Hymenoptera oF MINNESOTA 197

BEY DA
As in Diapriidae, but labial palpi with three joints.

“An extensive and but slightly studied group closely related to the
Diapriinae and formerly confused with them. . . . Nothing is
known of the habits of the species
comprising this group, altho Nees
von Esenbeck and others believe they
undergo their transformation within
[the larvae of Diptera that inhabit
fungi. From their close structural
resemblance to the Protoctrypinae,
this supposition is probably correct.”
Ashmead on Belytinae—Bull. U. S.
Nat. Mus. No. 45, p. 345, 1893.
Tee achonie ctalrlavicnuda: Belyta fulva Cameron, is recorded
UES. Nat Muss Bull: 45: from Bolitophila luminosa.

J ACROPIESTA-~€aum

SERPEIDAE

Trochanters with two joints or stigma very short and broad. Antennae inserted
on middle of face; wings present; wings may be absent; front wings when present
with a more or less distinct stigma; mandibles without teeth; antennae with thir-
teen joints.

Serphus obsoletus Say is parasitic on Stelidota stugosa, having
been reared from the latter insect by Professor Comstock.

S. caudatus Say is widely distributed over the U. S. and prob-
ably occurs in this state.

S. clypeatus has been reared
from a tree fungus from which
Melandryid, Mycetophagid, Staphy-
linid and Scaphidiid beetles were
obtained.

An _ unidentified Serphus was
taken at Itasca Park, Sept. 1, by

ie tes Va

Pee © RMD ANE:

Similar to Serphidae, but mandibles with
teeth, and antennae with fourteen or fifteen
joints.

Members of the family are para- :
: : Fig. 838. Helorus adoxr Provy.,
sites, typical of the group. zy Sema yl See a

198 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

“So far only a single species (of Helorinae) has been detected
in our tauna.” Ashmead, p. 331, Proc. UW Ss. Nat. Mus) 45,0895:
Helorus paradoxus Prov. is parasitic on the cocoon of Chrysopa. It
occurs in Minnesota. The genus Helorus is represented in Europe
by several species.

PELECINIDAE

Trochanters with one joint; antennae with fourteen joints; mandibles without
teeth; stigma very narrow, long; antennae inserted on middle of face; abdomen of
female greatly lengthened, about five times the length of head and thorax united,
composed of six segments; male abdomen clavate.

The male in this family differs
strikingly from the female in
the fact that the abdomen of the
former is not elongated.

Pelecinus polyturator Drury,
occurring in Minnesota, is a
striking species, the female hav-
ing a long slender abdomen in
marked contrast to the short ab-
domen of the male. The latter
is rarely seen. The species is

parasitic on grubs of the May

Fig. %. NOGA aon Drury, beetle (Lachnosterna), and is
emale,

common over most of the tem-

perate parts of the New World.

FORMICOIDEA

A deep constriction at the base of the first abdominal segment conspicuously
separating the abdomen from the thorax; the first abdominal segment forming a scale
or knot (petiole).

All true ants occur
in this super-family
and in the single fam-
ily which alone rep-
resents the group.

True ants vareat
once recognized by
the presence of one
or two knots or scales

at the base of the ab-
domen. Fig. 85.

Formica sanguinea Latr.

THe HyMENOopPTERA OF MINNESOTA 199

More than 2,000 species have been described, and it is estimated
that there are probably 5,000 species in existence. Distinctively social
insects for the most part, each colony is characterized by the presence
of one or more queens, living in harmony (in this respect differing from
social bees). There are also in each colony, worker ants which may
be represented by more than one class, and in some species we find
soldiers whose duty it is to fight for the colony they represent. The
workers are sterile or undeveloped females. The soldiers are workers
with large heads and powerful jaws. Their functions are those of

Fig. 86. Formica fusca L., female.

guarding the nest, fighting, crushing seeds, etc. Both male and
female ants in most species are winged at time of mating, and it is
no unusual thing in summer to see swarms filling the air during their
nuptial flight. After this is accomplished, the females strip off their
wings and proceed to egg-laying. There are, however, certain species
in which wings are never developed. Where one or both of the sexes
are wingless, mating must take place on or in the ground. The eggs
of ants are white or yellowish and hatch in about fifteen days, tho
at least one observer (Lubbock) claims a longer time is required, from
30 days to six weeks. The pupal stage lasts from three to four weeks.
The pupae are carried about by the workers to different places in the
nest as occasion may require, and if one disturbs an ant nest in sum-

200 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918§

mer, the occupants will be seen running excitedly about, carrying the
yellowish pupae in their jaws. These pupae are popularly supposed to
be the eggs.

Historically, ants are more prominent than any other insect, their
industry is often cited, and the habits of ants, in colony life, have been
made the object of profound study. Scholars have marveled at their
seeming intelligence evidenced by a “language” (an apparent communi-
cation by means of their antennae), by their care of aphids from which
they obtain a pleasing nectar, by their enslaving ants of other colonies,
by their storing vegetable tissue in their nests, which later forms an

Fig. 87. Lasiuws sp. female.

excellent culture for the growth of a fungus used by the ants as food.
Recognition of friends even after separation, is effected, as above
indicated, by antennal touch; and an ant in distress causes solicitude
amongst the others. On the other hand, they are equally quick in
recognizing enemies, or ants from another colony, and such recogni-
tion means a battle royal.

Further examples of what was regarded by early observers as
intelligence on the part of ants are not lacking; mud “sheds” are some-
times built by them over colonies of aphids, feeding in the open air,
thus protecting these insects from which they obtain nectar; the ant
genus Lasius carries plant lice to suitable plants where an abundance
of food is assured, and it is claimed, in the autumn, takes the eggs of
aphids into its burrow for protection against winter cold.

Tue HyMENopTERA OF MINNESOTA 201

In spite of the early beliefs that the complex actions of ants must
be accounted for on the ground that these insects possess intelligence,

Fig. 88. Lasius sp. male.

modern scientists have denied
the possession of psychic facul-
ties on the part of ants or other
insects. Bethe has made a care-
ful study of the ecology of this
group as a result of which he
states “they learn nothing, but
act mechanically in everything
they do, their complicated re-
flexes being set off by simple
physiological stimuli.”

Some ants make sounds by
tapping or scraping leaves with
their heads (by inference, there-
fore, ants can hear).

The bite of some species, as
many of us are aware, is pain-
ful. They are extremely coura-
geous, battling fiercely with hos-
tile colonies. Their relative
strength is out of all proportion
to the size of the insects; we

frequently see ants dragging dead caterpillars or grasshoppers many

times their size and weight.

z Fig. 89.

Myrmica sp. female.

0

bo

SEVENTEENTH Report STATE ENToMoLocist oF MINNESoTA—1918

Bb)

For an exhaustive account of ants, the student is referred to
that excellent work of W. M. Wheeler, “Ants, Their Structure, De-
velopment and Behavior’—Columbia University Press, 1910.

Fig. 90. Camponotus herculeanus L. sub species
pennsylvanicus De Geer.

FORMICIDAE
With the characteristics of the sub-order

In this, the only family of the suborder, we find familiar and in-
-eresting species, as well as exotic forms exhibiting most wonderful
traits.

Lasius niger, var. americanus is the little ant of our lawns and
walks. It is sometimes called the “corn louse ant” because it acts as
nurse for the corn root louse, Aphis maidiradicis. Packard says of
this species “The little yellow ant, abundant in parks and about houses
in New England generally swarm on the afternoon of some hot day
in the first week in September, when the air is filled toward sunset with
myriads of them. The females after their marriage flight in the air
may then be seen entering the ground to lay their eggs for new
colonies.”

An account of the relations of ants to aphids or plant lice might
easily be sufficient to fill a good sized volume. The basis of this amic-
able association lies in the fact that the sweet nectar elaborated from
sap by aphids is very attractive to ants, and they frequently resort to
tapping the plant lice with their antennae to induce them to give up the
liquid. This caress or tapping frequently results in a louse emitting,
not through the honey-tubes as originally supposed, but through the
anal opening, a drop or two of this fluid, which is eagerly eaten by the
ant. This process is sometimes alluded to as “milking the aphids,” and

THe HyMENopTerA OF MINNESOTA 203

plant lice have been called “ants’ cows.” Because the ants in many
cases act as nurses for plant lice, protecting them from harm in vari-
ous ways, and encouraging their increase, they are indirectly injurious
to the farmer, orchardist, and gardener. An orchardist who sees large
numbers of ants on his trees, must not infer that they are themselves
working injury to the tree. A careful search will doubtless disclose
large numbers of plant lice.

Ants are also associated with insects other than aphids. One finds
in their burrows ants’ nest beetles (Pselaphidae and other families)
also Hemiptera and Orthoptera. A few crustaceans also live with ants.
Some of these aliens in ants’ nests are parasites, some are messmates.
Of 1,177 species of insects recorded by Wasmann in 1900 as living for
a part or all of their time in ant nests, 993 were beetles (Pselaphidae,
Staphylinidae, Histeridae, Silphidae, etc.), 76 were Hemiptera (plant
lice and scale insects ), 39 Hymenoptera, 26 Lepidoptera larvae, 20 Thy-
sanura, 18 Diptera, 7 Orthoptera larvae, 34 mites and 20 spiders.

Monomorium pharaonis is the tiny house ant introduced into this
country from the Old World, barely visible, yet sometimes a great pest.
To be successful in eradicating it from a house, it is necessary to
destroy not only the workers of the colony but the queen or queens.
This is sometimes accomplished by means of fumigation. So tiny are
these insects that it requires “17,000 individuals to weigh one gram.”
(Cambridge Natural History. )

All of our native ants, with the possible exception of the house
ant just mentioned, live in galleries and chambers in the ground. It is
said that some species dig as deep as nine feet. The underground
excavations are generally accompanied by hills of various sizes on the
surface.

Conditions under which ants are troublesome are so varied that
individual cases should be referred to Experiment Station authorities.

The family is well represented in Minnesota Camponotus, Lasius,
Formica, Myrmica and A phaenogaster.

CHRYSIDOIDEA

Abdominal segments not strongly differentiated as petiole and gaster; tegulae
present, wings usually well developed, sometimes vestigial or lost; hairs of dorsulum
simple, not branched or plumose; abdomen with three segments visible, segments be-
yond third hidden.

These are the most brilliantly colored of the wasps. Some may be
iniquilines or “guests,” though Ashmead believed they are all para-

204 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

sites (Psyche, May 1894). Walsh has bred Chrysis caerulans from the
potter wasp. The species are small, but conspicuous on account of
their brilliant coloration, generally metallic green or blue. They
run or fly rapidly in the hot sunshine and in England have been
given the name of “cuckoo flies,’’ because of their resemblance in habits
to the European cuckoo, 1n that they steal into the nests of fossorial
wasps or bees, as the cuckoo does with other birds, when the owner is
away, and lay eggs therein. They are most persistent parasites and an
incident is on record where an enraged wasp returning to her nest and
finding a “cuckoo fly” on the point of leaving her egg there, attacked
the latter, and being unable to sting her because Chrysidids double
themselves up and present only an armoured surface, gnawed off the
parasite’s wings and threw her out on the ground. The unwelcome
and disabled parasite however, after the departure of the rightful
owner, crawled up the post and into the nest wounded as she was, and
deposited her egg before dying.

CHRYSIDEDAE.

With the characteristics of the sub-order

The insects of this family are often called ‘cuckoo flies” or “gold
wasps.”

The only family in the suborder and hence partakes of all the
characteristics given above. The species are well distributed over most
parts of the world. While a few forms attain a length of ™% inch or
more, they are for the most part small insects. Their bodies are strik-
ingly stout. The abdomen of some species is tipped with red. The
sting has no poison sack and is at the end of a retractile tube consist-
ing of the posterior abdominal segments. There are over 400 known
species which are guests or parasites in the nests of bees and wasps.

Chrysislauta, C. (Tetrachrysis) caerulans F. (see colored plate 1).
C. (Tetrachrysis) nitidula F. C. (Oleochrysis) pacifica Say, and
FHedychrum sp. occur in Minnesota. Tetrachrysis sp. taken in Mar-
tin County on Aster in September.

VESPOIDEA

Wings usually well developed, sometimes vestigeal or lost; body not flea-like;
wings usually with venation well developed; trochanters composed of one joint:
cutting edge of mandibles turned inward, their tips meeting or overlapping when
mandibles are flexed toward mouth.

This familiar group contains, besides some parasites, our social
wasps, strictly predaceous and insectivorous. They feed their young

THe HyMENopTEeRA OF MINNESOTA 205

with chewed insects for from 8 to 15 days, or to the end of their larval
life. They do not store up food, and colonies persist for only one sea-
son. In the more common species, nests consist of comb and envelop-
ing layers made of a papery material secured by scraping wood fiber
from weather worn boards and posts and mixing it with a salivary
secretion. They will take paper itself when sufficiently wet and pulpy.
Here occur our “yellow jackets” and “hornets.” These particular
insects are fond of meat and are attracted to exposed beef carcasses
in butcher shops and elsewhere.

BETHYLIDAE

Wings not folded longitudinally in repose; wings may be absent or reduced; no
constriction between first and second abdominal segments; discoidal cells obsolete, or,
if the first is present, it is petiolate; head oblong; antennae with twelve or more
joints; fore tarsi of female never chelate.

For an interesting account of the life his-
tory, ‘ot “a ‘Bethylid, see Howard's “Insect
Book” p. 34, where Mr. Busck’s observations
upon Laelius trojodermatis Ashm., parasitic
on Dermestid larvae, are published at some
length.

Pseudisobrachium myrmecophilum Ashm.
lives in ant nests, as does also P. mandibulare
Ashm. Neoscleroderma tarsalis Ashm. 1s

YG -TOPUS-tamen parasitic on Silvanus surinamensis. Other
Fig. 91. Gonatropus flavi. {fOrms are parasitic in various beetles. Go-

itor ed) SNut. Mus. “niozus sp. is parasitic on the codling moth.

DRYINIDAE

As in Bethylidae, but the head is transverse, subquadrate or globose; antennae
10-jointed; stigma large; fore tarsi of female chelate.

Dryinus ormenidis Ashm. is parasitic on Ormenis pruinosa and
O. septentrionalis, and the latter insect is also parasitized by Gonatopus
typhlocybae Ashm.

SCOLMDAE

Females winged. Wings not folded longitudinally in repose; a constriction be-
tween the first and second abdominal segments; legs of usual length; posterior femora
when directed backward not reaching to middle of abdomen; sternellum large, sharply
defined, extending between intermediate coxae; tibiae usually flattened with bristles
exteriorly.

206 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

These are large powerful Hymenoptera, usually hairy, black,
generally with bands or spots of red and yellow. Some of the species
prey upon the larvae of lamellicorn beetles, the female Scoliid pene-
trating the ground to find the lar-
vae. Tiphia inornata, ‘shiny,
black, 1s parasitic on white grubs.
Numerous wingless forms occur
in the family, the larvae living
parasitically at the expense of
other Hymenoptera.

Fig. 92. Tiphia inornata, a white grub

parasite; a. adult; b. head of larva; In the genus Elis, the females
ce. larva; d. cocoon.—From Insects of

RE Se tO! are much more robust than the
males and have short antennae,

while the males are long
with slender antennae, and
the radial cell, unlike that
in the female, touches the
costal margin of the wing.
This genus is quite com-
monly seen on the flowers
of golden rod and on flow-
ers of umbellifers. Elis
quinquecincta Fab. and
Campsomeris plumipes
Drury, occur in this state. Fig. 93.

Go

Myzine sexcincta Fab. female=Elis
quinquecincta F.

SAPYGIDAE

Females winged. Wings, when present, not folded longitudinally in repose: a
constriction between first and second abdominal segments; legs as in Seoliidae; ster-
nellum not defined; intermediate coxae usually contiguous; tibiae not flattened; apex
of abdomen in male without appendages; eyes deeply emarginate; abdomen usually
marked with yellow or white.

All species said to be parasitic though some are reported as
guests in the nests of some bees. The genus Sapyga has smooth slen-
der body ornamented with yellow; it lays its eggs in the cells of Osmia,
the larva consuming the stores which the latter has laid up for its
young. One species of Sapyga has been bred from Pelopaeus cemen-

tarius.

I. L. WOOD, DEL BUR. ENGRAVING, MPLS,

MINNESOTA HYMENOPTERA

Plate 3.

THe HyMENopPTERA OF MINNESOTA 207

METHOCIDAE

Wings, when present, not folded longitudinally in repose; constriction between
first and second abdominal segments; legs of usual length; posterior femora when
directed backward not reaching to middle of abdomen; sternellum not defined; inter-
mediate coxae generally contiguous; tibiae not flattened; clypeus transverse, very
much wider than long; eyes usually entire; female thorax divided into three parts;
apex of abdomen of male armed with single spine. j

The family is a small one, the Connecticut volume listing only one
genus and species. Methoca stygia Say, described by Say under the
name of bicolor, “has a black head, while the remainder of the insect
is almost entirely castaneous. The male is black with the wings
dusky.” This species resembles an ant.

MYRMOSIDAE

Same as Methocidae, but female thorax divided into two parts, prothorax being
well separated; apex of abdomen in male without spines; females always apterous.

We figure a male Myr-
mosa unicolor which oc-
curs in Minnesota and is of
general distribution over
the U. S. and Canada.

MUTILLIDAE

Same as Myrmosidae, but fe-
male thorax undivided; apex of
abdomen in male with two
spines.

All parasitic, and for the
most part in the nests of
wasps or bees wherein at times they may play the part of guests.

There is a striking difference between the sexes; the females are
wingless, the males winged. (Morawitz states that “wingless males
occur in two species.”) They closely resemble ants but have no node
or knot at base of abdomen. The females are provided with powerful
stings. Members of the family are also characterized by a velvet-like

Fig. 94. Myrmosa unicolor. Male.

PXPLANATION OF COLORED PLATE 3

16. Megachile (Xanthosarus) latimanus Say.
17. Ceratina dupla Say.

18. Xenoglossa (Peponapis) pruinosa Say.

19. Melissodes sp.

20. Bremus borealis Kby.

21. Psithyrus laboriosus, var. contiguus Cress.
22. Bremus ternarius Say.

23. Bombias separatus Cress.

208 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

Vig. 96. Dasymutilla cypris Blake.

Fig. 95. Dasynutilla
vesta Cress.

Fig. 97. Dasymutilla bioculata Cress. Fig. 98. Dasymutilla ferrugata Fab

MUTILLIDAE

THe HyMENOPTERA OF MINNESOTA 209

pubesence over their bodies, upon which occur sharply outlined mark-
ings of bright colors, or ivory-like spaces. Some of the species are
bright red, others yellow or orange. They are frequently called ‘“vel-
vet ants,” also “cow ants” and “‘cowkillers.” The family is distributed
over the entire world, but is apparently most common in South
America. About two hundred species occur in the United States,
largely in the southwest.

Dasymutilla ferrugata F., D. macra Cress., D. cypris Blake, D.
(Bruesia) asopus Cress., D. vesta Cress., D. bioculata Cress., Nomiae-
phagus sanbornii Blake, Mutilla (Sphaeropthalma) mutata Blake oc-
cur in Minnesota.

PSAMMOCHARIDAE
(Pompilidae )

Wings not folded longitudinally in repose; a constriction between first and
second abdominal segments; legs very long, posterior femora when directed back-
ward extending beyond middle of abdomen,

These are , slender
long-legged wasps with
abdomen united to thor-
ax by a very stout stalk.
They are generally vel-
vety black or blue, often
with orange bands;
wings are usually black
and constantly kept in
jerky motion while the
insect is moving about.

The family is almost

cosmopolitan in its
Fig. 99. Psammochares scelestus Cress. range. The species are
large, many reach 2 or 3

inches in length. They are frequently seen running rapidly over the
ground “with quivering wings and vibrating antennae.” ‘Their sting is
capable of inflicting a painful wound. Spiders are their special prey
and they can easily conquer the largest spider. They are frequently
called “spider wasps.” Their nests, usually in sand, are stored with
spiders and caterpillars. In Texas, Pepsis formosus Say attacks ta-
rantulas and is called “the tarantula killer.’ For an interesting ac-
count of the habits of Pompiloides (Pompilus) and Agenia, see “The
Spider Ravishers” by G. W. and E. C. Peckham, p. 125 et seq. Wisc.

210 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

Geol, jand Nat! Hist. Survey. Bull. No: 2, Sct“ Series: Novel whos
Fabre’s observations on Calicurgus see p. 157 “The Life and Love of
the Insect.” See also quotations from Fabre on pp. 101, 102, 103 Vol.
Vi; Camb. Nat. History.

Perez states that when Pompiloides has obtained a spider to provi-
sion its nest, it is sometimes pursued by Ceropales, another Psammo-

NG

Fig. 100 (Psammochares) Episyron biguttatus Fab.

charid, which lays an egg on the spider, thus providing food for its own
young.

The following occur in Minnesota (Pompilus) Psammochares
argenteus Cress.; (P.) P. tenebrosus Cress.;(P.) P. scelestus Cress.;
(P.) P. luctuosus Cress.; (Psammochares) Episyron biguttatus Fab.,
Agenia sp. Psammochares sp. taken in Rock Co. in Sept. and Crypto-
cheilus in Itasca Co. in Aug.

EUMENIDAE

Wings always present and folded longitudinally in repose; claws dentate; two
forms, males and females; middle tibiae with one or two apical spurs.

These are solitary, predatory wasps storing their cells with vari-
ous kinds of insects. They may bore in pith or in wood, or make mud
nests. It is the only family of solitary wasps whose members fold
their front wings longitudinally as social wasps do.

The common so-called “potter wasp” Eumenes fraterna occurs
here. It attaches its graceful vase-like mud nests, frequently

with small stones imbedded in the wall, to low plants and

THe HyMENOopPTERA oF MINNESOTA PAUL

bushes. These nests are said to have served as models for early In-
dian pottery.

The group is of great economic importance, valuable to fruit
growers and farmers, for its members prey upon caterpillars and larvae
of beetles, many thousands of which it destroys each year. Some-
times as many as from six to a dozen are found in one cell. Cater-
pillars are first paralyzed by being stung, and, to insure safety for the
single egg, the latter is suspended by a thread from the roof of the
cell. The different species destroy numbers of tineids, geometrids,
tortricids, and noctuid moths during the season.

There is no worker caste in
this family, all duties being per-
formed by the perfect female.
A few of the species resemble
“yellow jackets” so closely that
they fill one with alarm.

In some genera, Eumenes for
example, the pedicel at the base
of the abdomen is very elongate,

Fig. 101. Odynerus flavipes and its nest built Ww hile 7 others, It 1s strikingly
HE EE SOUL ftekee LON ENe short. In fact, Odynerus has a

sessile abdomen.

Odynerus capra Sauss. provisions its cells with the larvae of the
destructive larch saw-fly. This genus lives in holes in walls, in posts
or other woodwork, in burrows in earth, or in stems of plants.

Ashmead states that in Florida he has observed O. errynis St.
Farg. making its nest in the lock of his front door and in old holes
in his board fence. He also reared it many times from cells con-
structed in old oak galls. C. V. Riley found an Odynerus cell in the
tunnel through the center of a spool. Fig. 101.

The following species may be credited to Minnesota: Odynerus
(Ancistrocerus) capra Sauss., O. foraminatus Sauss., O. molestus
Sauss., (see colored plate 1.) Eumenes fraterna Say, on Aster in Aug.
and Sept., Odynerus sp. taken at Itasca Park, Itasca Co. Aug. 22 and
29 and Sept. 1, in Roseau Co. Aug. 19 and in Rock Co. Sept. 11.

VESPIDAE

Same as Eumenidae, but claws simple. Three forms, females, males, and work-
ers; abdomen either sessile or petiolate.

This family contains our social wasps, living in communities and
constructing dwellings of papery-like material. This is made of woody

212 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

fiber, gathered from old fences, sheds, etc., chewed up and cemented
by glandular secretion. A colony consists of males, females and
workers, the latter being imperfect females. These carry on all the
industrial work of the colony while the perfect females are egg lay-
ing. The nests are only used for a single season, the cold weather of
fall killing off all but the young females. Even in the tropics, the
colonies die off annually. While Vespula arborea and V. sylvester and
V’. norwegica, as well as others, suspend their nests from trees, bushes
and elsewhere, ’. germanica and V. vulgaris form nests below the sur-
face of the ground.

Females that have hibernated, start their cells in early part of
summer; “the solitary female wasp begins by making three saucer-
shaped receptacles in each of which she deposits an egg; she then pro-
ceeds to form other similar shaped receptacles, until the first eggs
deposited are hatched and the young grubs require a share of her at-
tention. From the circular bases, she now begins to raise her hexagonal
cells, not building them up at once, but from time to time, raising them
as the young grubs grow.” Proc. Ent. Soc. London 1858 p. 52.

Next to Polistes, Vespula (Vespa) is the most abundant genus.
Members of both of these genera feed their young upon the chewed
up fragments of Lepidoptera and other insects. Adult yellow-jackets
feed on meat, fresh or decaying, on insects, dead fish, exposed
fruit, raw or preserved, and on all sweet material. Vespula (Dolicho-
vespula) maculata, the bald-faced hornet, is perhaps the best builder
of globe nests; V. germanica and V. cuneata (“yellow jackets”)
usually build in hollows in stumps or in stone fences or underground.
Sometimes, however, their nests are found suspended from bush, tree
or building. One may see in the spring, the single comb nest made
by the queen of Vespula, suspended from bush or elsewhere, partially
enclosed in paper covering.

Both Polistes and Vespula are subject to parasites; the former is
sometimes parasitized by Xenus a beetle belonging to the Stylopidae.
Vespula is attacked by Stylopids, and by at least two species of Ichneu-
mons.

Underground wasp nests, which may become very large, can be
destroyed by pouring into the nest at dusk, a little bisulphide of carbon.
The large paper nests of hornets may be rendered untenable by drench-
ing them with kerosene. It is safer to do this after dark if possible.

THe HyMenoptera oF MINNESOTA

213

If the drenched nest is not attached to a building or fence, it may be
burned after this application of kerosene.

Minnesota species are as follows: Vespula vidua Sauss., Vespula
(V.) germanica F., V. (V.) vulgaris L. (see col. pf. 1), V. (V.) con-
sobrina Sauss., V. (Dolichovespula) maculata L., V. (D.) diabolica

Sauss., Polistes pallipes Le.P—=P. metricus Say.

Polistes sp. taken

in Rock Co., Fillmore Co., and Martin Co. in Sept.

NOMENCLATURE OF WING PARTS IN THE DRAWING OF

Chlorion (Ammobia) ichneumoneum

OLED SYSTEM

Veins

Costal

Subcostal

Median

Submedian or anal

Radius or marginal

Basal

First ‘transverse cubital
Second transverse cubital
Third transverse cubital
Transverse medial
Discoidal

Cubital

First recurrent

Second recurrent

Subdiscoidal

Cells

Costal

Median or externo-median
Submedian or interno-median
Anal

Marginal or radial

First submarginal or cubital
Second submarginal

Third submarginal

Fourth submarginal

First discoidal

Second discoidal

Third discoidal

First apical

Second apical

Stigma

Front

COMSTOCK-NEEDHAM SYSTEM
Wings

Veins

CostavorG
Sc+R+M
Cubitus or Cu
A

j Ist abscissa. radial cross-vein or 7,
< 4th abscissa R,; recurved tip Sc.+
( Ry

Medio-cubital cross-vein and Media
R,; and r-m
R;
R,
M,+Cu,
Ist abscissa M,, 2d abscissa M,
M+R; at margin M,+R,,
Most,
Transverse part of M,

(1st abscissa) medial cross-vein
oa abscissa) M,

Cells
GiESe

M

Cue Gu;
Ist+2d+3d A
Agl Reale

Ist R,+R

Stigma or cell Sc,

1918

MINNESOTA

State ENTOMOLOGIST OF

SEVENTEENTH REPORT

214

‘qnoroouuo,) Jo BiojdousmsAH 94 WOIg—'sploooydg jo oanjonays [RordAy Swnauownauyor (miqgowwmp) UolwojyQ “ZOE ‘“BtA

Vi Loyal ; “{ Wh
V
l

a0 2 JO N

i He \

Tie
SRPUY

SLIP PT ofa! eae

SYP EY 9

THe HyMENopterA oF MINNESOTA 215

Hind Wings

Veins Veins
Costal Costa or C
Subcostal R+M
Median Cu and M,
Anal Ist Asvat tipelst AY and) 2d A
Radian or marginal R,; (at its tip)
Cubital m-cu and R,+,+M,
Discoidal m and M,
Transverse median M,
Transverse cubital Free part of media or M
Axillary 3d A

Cells Cells
Costal C+Sc+Sce,
Median M
Submedian Cu+Cu,+M,
Anal Ist A+ 2d A; 3d A
Marginal or radial Ry
Submarginal or cubital R-+R,+R,+R,
Ist discoidal M,+1st M,4M,
2d discoidal. 2d M,

SPHECOIDEA

Abdominal segments not strongly differentiated as petiole and gaster; tegulae
present, wings usually well developed, sometimes vestigial or lost; pronotum with its
hind angles or tubercles always distinctly remote from tegulae; hairs of dorsulum
simple not branched or plumose; abdomen with more than three segments visible,
segments beyond third not hidden.

This superfamily includes the solitary wasps (see also Eumeni-
dae, superfamily Vespoidea) which for the most part make burrows
and store their nests with insects which they have paralyzed by
stinging. For an interesting account of life history and habits of in-
sects in this group, see the excellent treatise by G. W. and E. G. Peck-
ham of Milwaukee “On the Instincts and Habits of the Solitary
Wasps,” Bulletin No. 2, Scientific Series 1, Wisconsin Geological and
Natural History Survey. Students should also read pp. 18 et seq. in
L. O. Howard’s “Insect Book,” Doubleday, Page and Co., 1904. The
student should also consult Fabre’s “The Hunting Wasps,” Dodd,
Mead & Co., 1915. Fabre’s observations are by no means confined to
wasps of this superfamily.

AMPULICIDAE

Mesosternum produced posteriorly into an elongate process which is cleft or bi-
furecate apically ; middle tibiae with two apical spurs; prothorax long; femora swol-
len near middle; abdomen petiolate, no constriction between the first and second
segments.

Species in this group are very rare. An European species lives
on cockroaches. The only genus listed in the Hymenoptera of Con-
necticut is Rhinopsis, small wasps, not quite ™% inch long, black.

216 SEVENTEENTH Reporr STATE ENToOMoLocIst oF MINNESOTA—1918

PREOIMUT Pep yjley
Vay SOPH ORLLA Jobe ScusfefVuimn

AOL C/E
Oa \ \ LTCSEGUTIL O17

\ ‘ \ | SV CTHIOM LMI
/ | hia

Ta

F FOOSE
L7CSCQOISI CL IMM

) ef GOlCliea

Fig. 108. Thorax of Chlorion (A.) ichneumoneuin.— From The Hymenoptera of Conn.
4 I

NYSSONIDAE

Labrum entirely covered by clypeus, or at most with only apex visible; meso-
sternum normal, not produced into a forked process posteriorly ; middle tibiae with
two apical spurs; abdomen sessile or
sub-sessile, without a constriction be-

tween the first and second segments.

Nysson, Alyson, Gorytes, and
other representative genera nest
in sand. We have but little
knowledge of their habits.

The following species are
found in Minnesota: Pseudopli-
sus phaleratus Say, Nysson mel-
lipes Cress., Gorytes albosigna-
tus Fox, G. canaliculatus Say,
Alyson trianguliferum Prov.,
A. oppositus Say, A. melleus
Say.

Fig. 104. Nysson aequalis Patten.

N

THe HyMeENopTerA oF MINNESOTA 21

PSENIDAE

Antennae inserted near middle of face; mesepisternum with a dorsal and ventral
plate; abdomen petiolate; wings with three cubital cells.

This family has the rank of a sub-family (Pseninae, Family
Sphecidae) in the “Hymenoptera of Connecticut.”

The family is fairly well represented in Canada and the United
States. Psen concolor provisions its nest in hollow stems with Psyllids.
In 1913 Psen (Pemphredon) tenax was reported as attacking roses in
the Toronto district.

OXY BELIDAE

Head transverse; scutelleum margined; post scutellum armed with a spine, thorn
or forked process and with squamae; front wings with the first discoidal cell oblit-
erated, rarely distinct, most frequently confluent with the second discoidal cell.
First cubital and first discoidal cells confluent. Eyes with their inner margins sub-
parallel.

These small wasps burrow in
the sand and provision their
nests with flies, not stinging
them, but crushing the thorax
and thus destroying the princi-
pal nerve ganglia. The Peck-
hams found in some of the bur-
rows of Oxybelus quadrinotatus
a dozen flies in the same nest,
all with the thorax crushed.

We figure O. subulatus as a
Minnesota species.

Fig. 105. Oxybelus subulatus Rob.

CRABRONIDAE

Head large, quadrate or trapezoidal; scutellum normal, post scutellum unarmed;
front wings with the first discoidal cell always distinct; front wings with only one
sub-marginal cell; middle tibia with only one apical spur. Eyes with their inner mar-
gins strongly converging below.

Sometimes popularly referred to as “sand wasps.”’ Over cne
hundred species of this family are known. ‘They exhibit great diver-
sity of habits. Westwood says, “Those (species) whose economy has
been clearly traced, make their cells in wood, boring into palings, posts,
willows, stumps, pithy stems, etc. Their fore feet are well adapted for
digging and tunneling. Members of this group, like the preceding,
are said to crush the thorax of their prey, thus paralyzing the chief

218 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

nerve centers, rather than stinging their victims. Their nests are provi-
sioned largely with Diptera, though they also attack caterpillars,
spiders, aphids and other insects.

Crabro stirpicola was observed by the Peckhams to work night and
day for forty-two consecutive hours.

Minnesota species: Crabro trapezoideus Pack., Thyreopus sp.,
Crabro (Rhopalum) pedicellatum Pack., Solenius (Xestocrabro) sayt
Ckll. (See col. plate 2.) Anacrabro ocellatus Pack. Unidentified
species of Crabro were taken by Viereck on aster, golden rod and achil-
lea, at Itasca Park during Aug. 1913 and in Roseau Co. near Lake of
the Woods.

Fig. 106. (Crabro) Rhopalum pedicellatum Pack. Female.

PHILANTHIDAE

Head wider than the thorax; eyes most frequently normal, sometimes slightly
emarginate within, rarely deeply emarginate within; front wings with three sub-
marginal cells, intermediate tibiae with two apical spurs; abdomen frequently sessile
or sub sessile, rarely petiolate, not elongate, first segment frequently with a deep con-
striction between the first and second.

Members of this family look something like wasps. The males
exhibit brushes of long hairs on each side of the clypeus. Honey bees
are frequently their victims. Philanthus triangularis Fab. according
to Latreille, digs burrows in hot sandy situations and provisions its
nest with honey bees. A single bee is sufficient for rearing one
wasp. Living with the honey bee, which is defenceless against its
armor, this species stings its unsuspecting host on the under surface

THe HyMeENopTerA oF MINNESOTA 219

of the mentum; “afterwards the poor bee is subjected to a violent
process of kneading by which the honey is forced from it.” It is then
carried to the burrow of Philanthus. This burrow may be a yard long.
Some very interesting
and original observations
upon this species are to be
found on pp. 150 to 178 in
Fabre’s Social Life in the
Insect World, Century Co.
LONG and reterence to) the
Same especies arey ito) be
noted in “The Hunting
Wasps” by the same au-
thor.
The habits of Philanthus
Fig. 107. Philanthus dubius Cress., male. punctatus are discussed at
length in the Wisconsin
volume above alluded to. Aphilanthops frigidus Sm. provisions its
nest with queen Ants (Wheeler “Jl. of Animal Behavior,” Vol. III,
374-387, 1913.)

<n
Pe Sey

Fig. 108. Philanthus ventilabris Fab., male.

P. (Philanthus) punctatus Say, P. (P.) dubius Cress., and P.
(Pseudanthophilus) ventilabris Fab. are on record as occurring in Min-
nesota. Philanthus gibbosus Fab. taken by Viereck Sept. 10 in Rock
Co., and Philanthus sp. taken along lake shore in St. Louis Co., Aug.
15. Eucerceris gonata Cress. was collected at Gray Cloud Island,
Minn., in August. For an illustration of P. (P.) solivagus Say, see
Howard’s Insect Book, Pl. III fig. 3.

220 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

TRY POXYLONIDAE

Head not wider than the thorax; eyes always deeply emarginate within, or reni-
form; front wings with two submarginal cells, the second more or less indistinct;
middle tibia with only one apical spur; abdomen elongate, clavate, first segment
elongate, petioliform; a strong constriction between the first and second abdominal
segments.

These are slender wasps without
yellow bands on abdomen. . They
make cells in pithy plants, separating
them by mud partitions, or they make
mud cells against walls near or in
houses. These nests are stored with
spiders. Some of them, Tryposylon
albitarse, for example, according to
Walsh, select the deserted cells of a
mud dauber, provisioning its nest with
spiders. Another species, 7. carini-
frons, stores its cell with aphids. We
figure a female of Trypoxylon biden-
tatum Fox, from a Minnesota speci-

Fig. 109. Trypoxylon bidentatwm Fox,

female. men.

MELLINIDAE

Mesosternal suture wanting; intermediate coxae contiguous; middle tibia with
two apical spurs; abdomen with a more or less distinet constriction between the first
and second segments, first segment coarctate.

There is only one genus of this family, containing three species,
in America. There are therefore scanty if any observations on the
group in this country. Members of the genus Mellinus have been ob-
served on patches of cow dung feigning death, only to grasp a blue bot-
tle fly which came within reach.

The European species M. arvensis provisions its nest with small
Diptera, including Stomo.xys calcitrans, the stable fly.

SPHECIDAE

Antennae inserted above the base of the clypeus. Mesosternum not produced into
an elongate process; prothorax usually transverse; femora normally not swollen in
the middle; prepectus present; abdomen distinctly petiolate, no constriction between
first and second segments.

Comstock calls these ‘“‘thread-waisted” wasps because the most

striking characteristic is the fact that the first segment of the abdomen
forms a long, smooth, round petiole suggesting the name. Unlike the

THe HyMenoprera OF MINNESOTA 221

bees, the legs of these wasps are adapted only for digging and walk-
ing. They love the sunshine and move actively about in the heat.
Provided with a powerful sting, they are enabled to paralyze their prey
(insects) by stinging the principal nerve ganglia. Their victims stored
in their nests as food for their larvae, live many days but are incap-

Fig. 110. Pseudoplisus phaleratus Say.

_able of movement which would endanger the life of the sphecid egg or
larva. Caterpillars so stung may transform to pupae but are too weak
to carry the transformation further. Members of this family either
make nests in sand or act as “mud daubers,” building their cells of mud
and plastering them on walls.

Ammophila (Sphex) is a genus of giants. Many of them prey
upon the large Cicadas or harvest flies, easily carrying them off to
‘great golden dig-

‘

their nests. S. ichneuwmon sometimes called the
ger,” isa common form in the United States. Packard reports seeing in
late summer or early autumn nearly a dozen of these wasps engaged in
digging holes in a gravelly walk. These holes were from four to six
inches deep.

This genus also preys upon crickets. These insects, tho paralyzed,
survive for several weeks (Fabr.). Three or four crickets are some-
times found in each cell and a single Sphex may destroy one hundred
or more crickets in this way. The egg is placed on ventral surface of
victim between 2nd and 3rd pairs of legs, and hatches in three or four
days. In six or seven days, the larval Sphex has completely eaten out
the insides of the cricket, and it then attacks another. In ten or twelve
days the stock of crickets is exhausted.

S. W. Williston reports (Ent. News Vol. III p. 85), that Ammo-
phila (Sphex) yarrowi Cr. has been observed to bury four or five
caterpillars, storing them in her burrow for food of her future off-

222 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

spring. He further says, “the things that struck us most, were the
most unerring judgment in the selection of a pebble of precisely the
right size to fit the entrance and the use of the small pebble in smooth-
ing down and packing the soil over the opening, together with the in-
stinct that taught them to remove every evidence that the earth had
been disturbed.”

The relative strength of wasps of this genus is surprising. Ash-
mead saw A. (Sphex) cementaria Smith, after paralyzing a half grown
Sphinx larva by stinging, seize it just back of the head with its jaws
and since it was too heavy a burden to fly with, straddle it, and
drag it off to its cell, moving forward. A European species has
been observed “dragging a very large inflated spider up the nearly
perpendicular side of a sand bank at least 20 feet high.”

Ammophila pictipennis provisions its nest with cutworms. The
steel-blue Chalybion caeruleum stores in its burrows, crickets, locusts,
and spiders.

Minnesota species: Chlorion (C.) cyaneum Dahlb., C. (Pal-
modes) abdominalis Cress., C. (Priononyx) atratum LeP., Sphex
(Psammophila) luctuosa Sm., Chalybion caeruleum L. Sceliphron
cementarius Drury, Chlorion (Ammobia) ichneumoneum L. (see col.
pl. 2). Sphex pictipennis Walsh, S. robusta Cress., Chlorion (A.)
pennsylvanicum L. For illustration of the latter see Howard’s Insect
Book, Pl. VII, fig. 20.

Sphex sp. has been taken in Rock and Fillmore Counties in Sep-
tember.

LARRIDAE

Eyes most frequently normal, rarely emarginate within; hind ocelli normal or
aborted, or wanting; labrum small, not free; usually completely hidden by the ely-
peus; mandibles often emarginate on the under side; front wings with a distinct
stigma, and with two or three submarginal cells; middle tibiae with only one apical
spur; abdomen sessile, never petiolate; no strong constriction between the first and
second segments.

Fig. 111. Tachysphex terminatus Sm.
female.

THe HyMeENopTerA OF MINNESOTA 223

These wasps make burrows in sandy places and provision their
nests chiefly with grasshoppers and crickets.

They are active insects and very hard to net in the field. The
small Lyroda subita feeds its young daily with crickets. We have
recorded as occurring here Tachytes crassus Patt. and Tachysphex
terminatus Sm.

Fig. 112. Tachytes crassus Patton,
male.

ASA DATE

Abdomen depressed, dorsal surface flattened; intermediate tibiae with two apical
spurs; radial cell truncate; wings with three cubital cells. (Listed as a subfamily
in Conn. Hym.)

The males of this family are characterized by the possession of
very large eyes. Members of the group are partial to the Heteroptera
in the matter of food. At least two species select bugs and do not

paralyze, but kill them.

224 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

PEMPHREDONIDAE

Eyes normal, not emarginate within; ocelli distinct; labrum most frequently
hidden; front wings with two submarginal cells: middle tibia with only one apical
spur; abdomen sessile or petiolate, without a constriction between the first and second
segments. (Listed as a sub-family in Hym. of Conn.)

These are rather small, slender
wasps, of a shiny black color, which
burrow in pith of dry branches, mak-
ing very irregular and complicated
channels. They. frequently store
their nests with plant lice.

Pemphredon tenax Fox. occurs in

Minnesota, and Stigmus sp. has been
taken in St. Louis Co. in August.

Fig. 118. Pemphredon tenax Fox,
female.

BEMBICIDAE
Antennae inserted close to eclypeus; cheeks narrow, prepectus wanting; eyes
normal, not emarginate within; ocelli aborted, represented by sears; labrum large,
free, well developed, much longer than wide, triangularly elongated: front wings with
three submarginal cells; abdomen sessile, never petiolate, no strong constriction be-
tween first and second segments; otherwise as in Sphecidae.

These wasps nest in the ground, frequently in colonies, and provi-
sion their nests with Diptera or Hemiptera. The biology of this group,
particularly of Bembe.x, has been treated by various observers. An ex-
tremely interesting account of Bembex occurs in Fabre’s “The Hunt-
ing Wasps.” To the question as to why Bembex does not paralyze her
prey by stinging, Fabre replies that her abdomen is so formed that
shevcannotdo-so. Parker (Proc. U.S. Nat.’ Mus; Vol, 52 -pi2snee
seq.) discusses at length the biology of the Bemicidae and in the course
of his remarks states his belief that a Bembicid wasp finds her skill-
fully concealed burrow by the sense of smell, citing several instances
where he greatly disturbed the surface over the burrow, even to the
extent of dashing water over it, but never succeeded in confusing the
female wasp.

A prominent member of this family is Sphecius speciosus Say, the
giant sand wasp or “cicada killer,’ which provisions its burrows
with different species of Cicadas. A Florida species preys upon the
large horse fly Tabanus atratus. Coquillet reported frequently ob-
serving, in California, Bembex fasciata storing its nest with Eristalis
tenax and other flies. Members of the genus Stizus (large hairy
bodied wasps) paralyze grasshoppers and other large insects (in-
cluding the dog-day cicada) and carry them off to their burrows.

THe HyMENopTERA OF MINNESOTA 225

The sense of direction appears to be well developed in this group,
for they cover their burrows so adroitly that there appears to be ab-
solutely nothing by which the exact position of the nest can be traced.
Yet Bembex flies to it without failing. At least one species, Bembex
spinolae supplies flies to the growing larva during the life of the larva,
digging away the soil from the entrance of the nest each time and
scraping it together again when she leaves the nest. B. rostrata also
makes frequent visits to its nest with fresh food.

Fig. 114. Left figure Sphecius speciosus Say, carrying a Cicada to her burrow. Right
figure, Cicada in burrow of Spheciws with full-grown larva of digger wasp feed-
ing.—From Insect Life.

A Tachinid fly of the genus Miltogramma lays eggs on victim
being carried to burrow by Bembex, and its maggot later eats this
store of provisions intended for the young Bembex larva.

Minnesota species: (Bembidula) Bicyrtes ventralis Say (Rock Co.
Sept.). For an account of the habits of this species see Parker, Proc.
WaswNat Mussel 52, p. 132: et: seq.

B. quadrifasciata Say. Ibid., B. spinolae LeP., Ibid. Microbembex
monodonta Say. (see col. pl. 2; also Vol. 52 Proc. U. S. M., p. 134 et
seq. ) Bembex spinolae LeP. was taken by Viereck in Sept. 1913 in
Rock Co.

226 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

CERCERIDAE

Mesosternum not produced into an elongate process; femora normally not swol-
len in the middle, prepectus wanting; antennae inserted much above clypeus; cheeks
broad, first abdominal segment much narrower than second; lower posterior margin
of propodeum rounded; a dorsal plate to mesepisternum.

Members of the
genus Cerceris make
burrows in the ground
and store them with
beetles. | These bee-
tles when captured
are stung between the
pro- and meso- thor-
ax. Some European
species ‘store their

nests with bees, others

Fig. 115. Cerceris fasciola Cress., female.

with beetles.
We figure Cerceris fasciola Cress., from a Minnesota specimen.
Viereck took Cerceris sp. on goldenrod and aster in Aug. and
Sept. in Rock and St. Louis counties.

SuBORDER APOIDEA

A deep constriction at the base of the first abdominal segment, conspicuously
separating the abdomen from the thorax; abdominal segments not strongly differen-
tiated as petiole and gaster; tegulae present, wings usually well developed, sometimes
vestigial or lost; pronotum with its hind angles or tubercles always distinetly remote
from tegulae; hairs of dorsulum branched ar plumose.

With few exceptions, these are all “bee-like” in appearance, differ-
ing of course from certain bee-mimicking flies (Syrphidae and Bomby-
iiidae) by the presence of two pairs of wings instead of one pair. Some-
thing like a thousand species are known to occur in North America.
Individuals are more or less hairy, and the tongue is always formed
for lapping, the hind legs are generally modified to carry pollen.

HALICEID AE

Females and most males with a flat triangular area on the apical dorsal abdominal
segment; clypeus hardly protuberant; labrum concealed except at base, posterior
angle of mandible not in front of posterior margin of eye; tongue acute, flat, rarely
filiform; labrum not free from mandibles and not as large as eclypeus; hind meta-
tarsus invariably narrower than tibia; marginal cell acute toward front edge of
wing; basal vein forming more or less perfectly an are of a circle; face with no pube-
sent depressions of fovae.

These are very small, for the most part short-winged solitary
bees (i.e., no specially developed workers), some of them brilliantly

THrt HyMENopTeRA OF MINNESOTA 227

blue and green in color. Altho solitary in the above sense, they
may occur in communities, a large number of individuals building in
the same territory. While each bee works for its own progeny, there
may be community labor as in making a gallery needed by a colony.

Work of excavating is carried on at night. The handsome little
bees of genus Halictus, only about 1/100 to 3/100 of an inch long, often
metallic in color, dig branched
tunnels seven or eight or more
inches long. They sometimes
occur in large colonies on the
sides of sand cliffs.

Minnesota species: Halictus
(Halictus) lerouxi var. rubrum
Ckll., Halictus (Agapostemon)
wrescens EF. (see col. plate 2.):
Hi CA.) radiatus Say, Teas)
texanus Cress., H. (A.) splen-
Fig. 116. Halictus (Agapostemon) radi- dens LeP., H. (Chloralictus ) teg-

atus Say, female. ularis Rob. H. (C.) pilosus Sm.,

H. (C.) pruinosus Rob., Chlora-

lictus) vierecki Crwfd., Augochlora sp. and O-xysloglossa sp. (aster

and golden rod, Itasca Co. in August), Halictus lerouxi Fab., lake

shore, Duluth, St. Louis Co., H. ligatus Say, Rock Co. Sept. 11, on

aster. Chloralictus sp. Itasca Co. in Aug., and Martin, Fillmore and

Rock Cos. in Sept. on aster, sunflower and golden rod. Evylaeus sp.

Itasca Co., Aug. 25, on Solidago. Lasioglossum sp. taken on sun-
flower and aster by H. L. V. in Itasca Park, Aug. 29.

ANDRENIDAE

Same as Halictidae but basal vein forming a more or less perfectly straight
line, and face with pubescent depressions or fovae, at least in female; hind femora
always with a pollen brush, or flocculus.

These bees are of moderate or large size. They resemble honey
bees, and are sometimes mistaken for them; generally, however, they
are smaller. A large number of species is known, most of them diggers,
and all of them solitary, although they almost always live in colonies,
constructing burrows in the ground and preferring sandy places, some-
times, however, selecting a gravel path. Andrena “villages” have been

228 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

observed, covering only one square rod of ground, that included several
thousand nests. The sexes are different in appearance and are rarely
found together. The cells are stored with pollen and honey.
Minnesota species:
Andrena imitatrix
claytoniae Rob., A.
(A.) — erythrogaster
Ashm., A. (A.) dun-
ningt Ckll. A. (A.)
carlimt Ckll. A. (A.)
bisaheis VierS eae
(A.) robertsom D. T.,
A. (A.) commoda
Fig. 117. Andrena (A.) mariae Rob., female with 2d Sm., A. (G28) sigiae
Eeecha Gee on left and enclosure on Rob.., Jl (A.) mariae
Rob., A. (A.) flavo-
clypeata Sm.,A.( Tra-

chandrena hippotes
Rob., A. (Trachan-
drena) crataegi Rob.,
A. (A.) placida Sm.,
A. (A.) nubecula Sm.
(on goldenrod and
aster, Martinand Rock
counties “im, Séept.);
A. (A.) canadensis
Prov., A..\( A.) fragt
hs Sm,, A. (A.) lir-
ticincta Prov., AL Fig. 118. Andrena (T.) crataegi Rob., female.
(A.) cressoni Rob.,

A. (Pterandrena) helianthi Rob. (on aster, Martin and Itasca counties
in Sept.), A. (P.) asteris Rob.

DUFOUREIDAE

Females and most males with a flat triangular area on apical dorsal abdominal
segment; clypeus hardly protuberant, labrum concealed except at base, posterior an-
gle of mandible not in front of posterior margin of eye; tongue acute, flat, rarely
filiform; labrum free from mandibles and as large as clypeus.

Halictoides (Conohalictoides) novaeangliae Rob. is found in this
state. Visits flowers of pickerel weed.

THe HyMeENopTERA OF MINNESOTA 229

NOMIIDAE
Tegulae very large; glossa lance-linear, acuminate, shorter than mentum; man-
dibles bidentate, not bevelled; posterior angle of mandible not before posterior line of

eye; clypeus hardly protuberant; labrum usually small, concealed except at base
and with a basal process, metathorax produced beyond postscutel.

The type genus Nomua is a large one. Nomia (Eunomia) heter-
opoda Say occurs in Minnesota.

MACROPIDAE

Same as Dufoureidae, but labrum not free from mandibles and not as large as'
elypeus; hind tibia and metatarsus of equal breadth.

The genus Macropis occurs in this state (collected on Indian Hemp
along lake shore, St. Louis Co., by H. L. V.) WM. ciliata Patt. is some-
times found on Lysimachia terrestus.

PANURGIDAE

Same as Macropidae, but
hind metatarsus invariably
narrower than tibia; margin-
al cell truncate toward front
edge of wing.

We figure Calliopsis
sp. and Perdita sp. col-
lected in Minnesota. Pa-
nurginus has also been

Ape

Fig. 119. Calliopsis sp.

taken here on aster and gold-
enrod (Rock, Fillmore and
Martin Cos. in Sept.), Calh-
opsis andreniformis Sm. oc-
curs in this state, as does also
Panurgus sp. Fig. 120. Perdita sp.

NOMADIDAE

Females and most males with a flat triangular area on apical dorsal abdominal
segment; clypeus protuberant, or mandibles beveled so as to show all of labrum or
a great portion of it; labrum large without a basal process, tongue filiform; first and
second joints of labial palpi flat; first portion of sub-discoidal vein shorter than third
portion of discoidal vein.

Small, not very hairy bees, somewhat resembling wasps. They
are parasites in the nests of other bees. In accord with their parasitic

230 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

habits, their legs are not modified to carry pollen. These bees appear
to live on the best of terms with their hosts, and their larvae are fed
with the pollen and honey stored up by the latter.

Minnesota forms: Epeolus scutellaris Say, Nomada sp., Gnathias
sp. Triepeolus bardus Cress. (see col. plate 2), Centrias sp. Holono-
mada sp. Triepeolus is found in late summer on the Compositae.
Nomada is an early flier visiting aments of willow.

EUCERIDAE

Same as preceding family as to apical dorsal abdominal segment of males and
females; also as to clypeus, mandibles and labrum, tongue, and first and second joints
of labial palpi. But first portion of sub-discoidal vein distinctly longer than third
portion, and marginal cell bent away from costal vein; vertex crested.

Often densely hairy, of moderate size. Xenoglossa is one of the
chief agents in pollenizing the flowers of pumpkins, squashes, melons
and cucumbers.

Cemolobus ipomoeae Rob. visits flowers of the morning glory.
Melissodes (Anthedon) compta Cress. is illustrated in Howard’s In-
sect Book, Pl. III and Melissodes (M.) rustica Say in Fig. 12 pl. IV,
op. cit. Tetralonia atriventris Sm. is illustrated in Fig. 19, pl. II, op.
cit.

Minnesota species: Melissodes bimaculata LeP., M. (M.) rustica
Say, M. nivea Rob., M. perplexa Cress., Tetralonia speciosa, Melis-
sodes sp.. (see col. plate 3), Nenoglossa (Peponapis) pruinosa Say.
We have taken Melissodes on aster in this state in Aug. and Sept. in
Itasca, Martin and St. Louis counties.

EMPHORIDAE

Same as in Euceridae but vertex not crested.

There is no representative of this family in the Minnesota collec-
tion. Melitoma taurea Say is figured in Howard’s Insect Book, PI.
III, fig. 7, Emphor bombiformis Cress. visits flowers of morning glory
(Ipomoea) and marshmallow (Hibiscus).

ANTHOPHORIDAE

Same as Emphoridae, but marginal cell not bent away from costal vein.

These solitary bees are, in size, between a honey bee and bum-
ble bee. They are for the most part hairy and many burrow in the
soil, forming cells in underground tunnels and laying their eggs there-
in upon a mixture of pollen and honey. The cell is then closed. Some

THe HyMeENoprera oF MINNESOTA al

species in this family bore into wood, or they may occupy old burrows
of some carpenter bee. (Howard)

Anthophora (Clisodon) terminalis Cress, is the only species on
record in the state, taken on aster at Itasca Park in August.

HYLAEIDAE

Females and most males without a flat triangular area on apical dorsal abdominal
segment; second recurrent vein bent or directed outward before joining first portion
of subdiscoidal vein; tongue flat, bilobed; depressions or fovae on face; wings with
two closed submarginal cells; black and yellow markings.

These are the bees that Ashmead called the “obtuse-tongued car-
penter bees.” But few of them are parasitic. They burrow in the
pithy twigs of shrubs, frequently elder, where they construct their cells,
filling them with pollen and honey. Hylaeus sp. occurs in the state,
taken on aster in St. Louis Co. in August.

COELETRIDAE

Same as Hylacidae, but wings with three closed submarginal cells; black with-
out yellow markings; head and thorax more or less clothed with a dense pubescence ;
tongue flattened and broad. Hind femora, tibia and tarsi of females always with a
pollen brush or flocculus.

Moderate sized blunt tongued hairy bees, burrowing in sandy
places.

Fig. 121. Colletes conipactus Cress. Fig. 122. Colletes americanus Cress.

The females resemble somewhat the workers of the honey bee,
but the males are much smaller. Their burrows are lined with a deli-
cate parchment-like membrane, and are divided into several cells, six
or more, by parchment-like partitions. An egg is deposited in each
cell on or in a mixture of pollen and honey.

232 SEVENTEENTH Report STATE ENTOMOLOGIST oF MINNESOTA—1918

In Europe Colletes is parasitized by Miltogramma punctata, a
tachinid fly, which lays its own egg in the cell on the food intended for
the Colletes larva. Another parasite of this genus is the cuckoo-bee,
Epeolus variegatus.

We figure Colletes compactus Cress., and C. americanus Cress.
from Minnesota specimens. The first named has been collected from
flowers of Solidago and asters. Colletes sp. has been taken in Hub-
bard, St. Louis and Itasca counties in August.

SPELIDIDAE

Females and males as in Hylaeidae but second recurrent vein never strongly
bent or directed outward before joining first portion of subdiscoidal vein; tongue
filiform; no depressions or fo. ae on face. Wings with two submarginal cells; claws
left, inner tooth subapical.

These are bees with whitish
margins on the dorsal segments
of the abdomen. Females of
the genus Stelis, the only genus
in the family, lay eggs in Os-
mia’s cells in blackberry stems,
before the rightful owners have
oviposited. Thus the egg of
Stelis is lower down in the mass
of food than is the later laid
of Osmia. The larva of

2 FO
eg

oOo

Stelis grows more rapidly than
the Osmia larva and eats the
latter.

Stelis also preys upon a mason bee, Chalicodoma. Stelis (Chel-
yina) nitidis Cress. (see drawing), is a Minnesota species.

Fig. 125. Stelis (Chelynia) nitidus Cress.

MEGACHILIDAE

Same as Stelididae but claws simple or in some species with a basal tooth; labrum
entirely covered by the clypeus; hind tibiae with two apical spurs.

This family contains the leaf-cutting bees and their parasites, as
well as the mason bees. The latter earn their name by constructing
small earthen cells in various situations.

The leaf-cutting bee, Megachile, is the insect which cuts semi-
circular pieces from the edges of rose leaves, and from other tender
leaves. These pieces of green leaves are used to line the tunnel which

THe HyMenoprera oF MINNESOTA 233

this bee makes in a pithy stem or in solid wood. The genus is almost
cosmopolitan, being found in nearly all parts of the world. It is
about the size of a honey bee. Ashmead reported a Megachile nest
(Psyche. Feb. 1894) with “thirty cells arranged in nine rows of un-
equal length, the largest row contained. six cells. There must have

%9

been a thousand pieces of leaves used in the above.

The genus Osmia is an in-
teresting one; O. lignivora
bores in maple, forming cells
in its burrow. Ashmead, in
reporting observations on this
species (Psyche March 1894),
states “the tunnel was over
three inches long. Bless
contained five cells.” O. lig-
naria and O. pacifica build
cells under stones, while the
small O. simillima constructs
cells in deserted oak galls.”

It will be noted from the Fig. 124. Coelioxys octodentata Say,
above that the diversity of in- Gua Te,
stinct displayed in formation
of nests of various species is quite remarkable. They generally
choose hollow places already existing, excavations in wood, in the
mortar of walls, in sand banks, and elsewhere. O. tridentata makes a
burrow in the pith of bramble stems.

The following are found in Minnesota either present in our col-
lection, or on record as occurring here: Heteranthidium chip pewaense
Graen., type-locality—Indian village at junction of the Lower Tama-
rack and St. Croix rivers, Minnesota. Alcidamea sp., Andronicus sp.,
Coelioxys octodentata Say (see drawing), Heriades sp., Monumetha,
Anthidium sp., Megachile (Xanthosarus) latimanus Say (col. pl. 3),
Osmia (Ceratosmia) lignaria Say, Coelioxys sp. taken in Jackson Co.
on sunflower and aster Sept. 12.

CERATINIDAE

Females and most males without a flat triangular area on apical dorsal abdominal
segment; second recurrent vein never strongly bent or directed outward before join-
ing first portion of subdiscoidal vein; tongue filiform; no depression or fovae on
face; wings with three submarginal cells; apex of sixth abdominal segment in female

234 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

with a spine; first submarginal cell longer than second, and as long as third; hind
tibiae with a sparse pubescence; segments of the abdomen more or less constricted
at the sutures.

Small bees, smooth, frequently metallic in coloration (green, blue
or blue-black) boring in the pith of briars.

In connection with this and the preceding family and particularly
for a discussion of Osmia, the student would do well to read Fabre’s
“Bramble Bees and Others,’’ Dodd, Mead and Co., 1915.

Ceratina dupla Say, occurs here (see col. plate 3), collected by
H. L. V. in Rock and Martin counties in September, frequenting asters.

XY LOCOPIDAE

Same as Ceratinidae, but with first submarginal cell shorter than second; thorax
densely pubescent laterally; hind tibiae with two apical spurs; abdomen not elon-
gate, convex above.

This group contains many of the largest and most powerful-of the
bees and is widely distributed. The genus Xvylocopa contains black
or blue-black species, robust with shiny integument, more or less coy-
ered with hair. X. virginica is the. large carpenter bee, which bores
frequently in solid wood, or even, according to Howard, in lumber and
in joists of buildings. These burrows may be one-half inch in diameter,
and are sometimes found in beams about porches, sheds, rafters, palings
of fences, door frames and window sills.

An interesting statement has been published by Bingham (Brit.
Ind. Hymenoptera 1, p. 534), according to which X. rufescens Sm. is
“crepuscular, on fine moonlight nights its loud buzzing can often be
heard all night long.” Other bees are known to work at night, notably
Sphecodogastra texana Cress. On July 15 at Prescott, Wisconsin,
these bees were found working on evening primrose as late as 10 p. m.
and were not observed upon these or any other flowers in that vicinity
during the day time. Both males and females of this species have large
ocelli. (S. Graenicher in Bees of Northern Wisconsin, Vol. 1 Art.
POE,

APIDAE

Apical dorsal abdominal segment of males and females, second recurrent vein,
depressions of fovae on face, and submarginal cell as in Ceratinidae; tongue very
elongate, slender and always longer than mentum; apex of sixth dorsal abdominal
segment in female without a spine; first submarginal cell shorter than second; cheek
or malar space distinct. Hind tibiae with or without apical spurs, thorax densely
hairy; three sexes, females (or queens), workers and males.

These are the true bees, most of them social, and most of them

storers of honey. Volumes have been written upon the honey bee,
Apis mellifera L., to which works the reader is referred, for it is mani-

THe HyMENopTeRA OF MINNESOTA 235

festly impossible to do justice to the honey bee in a report of this kind.
For an excellent account of bee management, as well as the ecology of
Liewwoneyepee, sce Uhe ABC: Vand X]Y-Z. of Bee Culture; latest
edition, published by the A. I. Root Co., Medina, Ohio.

The honey bee is distributed practically over the entire globe and
it should be borne in mind that there is only one species, the appella-
tions “German,” “Italian,” “Carniolan,” etc., referring simply to strains
of the same species.

Next in importance, perhaps, is the group containing the bumble
bees, of which over 50 native species are known. A striking char-
acteristic of these bees is the abundant hair covering; and there is a
great variation in color of same, as well as in the size of the individ-
uals. They are distinctly social. Males, females and workers exist,
the workers not being distinguishable from the females, and if the true
queen dies, the smaller females may continue the colony. The nest is
made of dry grass or leaves in a hollow in the field in or under old
stumps, under boards, or even below the surface of the ground. In
the latter case there may be 200 or 300 individuals in a nest, but the
colonies on the surface are less populous.

In autumn, large numbers of males are produced, also new
queens. The colony as a whole then dies except a few fertilized
queens, which survive the winter, each destined to start a new colony
in the spring. The eggs first laid produce neuters or workers, later
males and productive females are produced. Certain female bees in
the colony, smaller than the queen, may help in egg-laying, and this
is sure to be the case if the true queen dies. About four weeks elapse
between the depositing of the egg and emergence of the perfect insect.

Bumble bees do not use cells twice, but form new cells on the rem-
nants of the old; consequently the nests may be quite bulky. They
are destroyed by several animals, either for the honey or for the larvae
contained therein. Field mice, weasels, and foxes are the chief ma-
rauders.

In the nest are found “honey tubs,” “pollen tubs” and the cells of
a “friendly parasite,” Psithyrus (Apathus), discussed below. Honey
is stored in empty pupal cells and in other special receptacles made en-
tirely of wax. Country boys are aware of these stores and rob the
nests.

Psithyrus (Apathus) is always found in and about bumble bee
nests. It is widely distributed and resembles a bumble bee very closely,

236 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

“each species of Psithyrus resembling the bumble bee with which it
usually lives.” Since the genus only appropriates a portion of the
food supply of its host, it may be re-
garded as a messmate or “commensal”
and not a parasite, though sometimes
destructive.

In observations made on the habits
of this bee, it has been observed that
it is not as industrious as the bumble
bee, only leaving the nest somewhat
before noon and returning toward
evening, and sometimes passing en-
tire days in the nest, consuming the
honey of its host. Since this “board-
er’ is much larger than its host, and

consumes a large amount of honey,

Fig. 125. Psithyrus ashtoni P . :
: edaa eaale: y the number of bumble bees raised in

an infested nest is naturally reduced.

The following species are found in Minnesota either present in
our collection, or on record as occurring here: Bombias auricomus Rob.,
B. separatus Cress., (col. plate 3), B. rufocinctus Cress., Bremus bor-
ealis Kirby, (col. plate 3), B. fervidus F., B. pennsylvanicus Deg.
B. affinis Cress., B. terricola Kirby, B. impatiens Harris, B. perplexrus
Cress., B. vagans Sm., B. ternarius Say. (col. plate 3), Psithyrus
ashtomi Cress., (Fig. 125), P. insularis Sm., P. laboriosus Cress., (col.
plate 3), Apis mellifera Linn. (various strains and hybrids. )

Viereck’s collecting in 1913 did not add to our list of known Min-
nesota species of bumble bees. He found the above forms well dis-
tributed over the state on aster and sunflower in August and September.

THe HyMENOpTERA OF MINNESOTA 237,

INDEX OF FAMILIES AND SUPERFAMILIES

(Colored plates 1, 2 and 3 face pages 148, 184, 207 respectively. )

/NINASTRIG LENS. Meteeae cain er oeaes Go Rca lets 165
Aimplicidiacwes sash ceieeacse- Cio
An heMidaietan ot asr eat seucicis ot oe ae.
ANTE MODIMOIGIAS. Goosneoncsooncbs 230
ADMITS Seodscodsosoneucdos 188
PATIL Mee Nis Bees ace ae PUR cats tee OF:
EAN Old ear VNR ee eee oCO
ING Out Aten Men ee Sea ee 159
INSTALL CACM tana eek eS
Banchitd adem sss. dee oe ook: 167
BD elivittdaete. mete. a. a nae a aes eee 197
Bembicidaen- aeons sae eae.
Bethivlidaes men oncirce arene 205
Braconidae ier st cak acto cos shyt cies 167
(CaillnnmomnGaen oo Sane aaeodooods oc 189
Capitoniidadesaeee sas eee 169
Cerapliromdaeuan. sae anaes 196
Gerarinidae Ae. hsc ose sen. 233
Geli versie sehen 8 ale eee en 155
@eCenidaeie yan eek Sot ee
Chalastocastraeeeeaeee ne eaeeias 152
CGiralerdtdaes sy. ri site are 192
@Ghialcidoidea eee er ene. 180
@hiysididae geet) sea cee eee 204
Ghinysidoidea) ir. ae ee 203
@impretdaey ea ee ee cee 158
@listovastrart.. consumo ee 164
Colletidtems ee ict aoe 231
Crabromidae see sees ee oe 217
Gymipidaee tas eee nee aati ye: 179
Cyipordeare wank ae acento a7
Diapiiidacwes nar meee een 196
Dipnomdacmen ce ere eee 159
Dyrayatalt ae ysrety. tei satel er ic ses eaten 205
Dinkounerdaesaue. oe eee ee
Blachertidaeaere sae see cee 186
eal alsin lalemeeans cant sete theo ees 186
IStaplonidaen ve eos h Gates ok eee 230
Biieymntidaere yen eese sees cee 188
Bintedombidae yn sees ae eee 185
PCE aerate. aac sake ohne 230
Rchiatrt dace net seeks eee 192
iB nlophidacran vcceiwnicc cost 186
Stamler ayewe ys 5 aise sic ote este ieniee 210
tp elimidaegened ee oe ere nan. 189
Banytomiddere. ie ates oe o 18)
EivamiiGnekrenm ae eicce ceil einicis. 169
isibid aleve tre eRe ee: 178
Romi cdacmaeey teeta LOL
IDG yeaMIGONGIEZ ao os Oh onou adladeca die 198
FlAlictidaekieew 7, aero eats 220
Eelonrdalesre 5.5: ers e eae cs 197
Fly deid aeea.nesesty. ns Pee cetionacs. 231

Dhalnidae whee see eae p ee 180
lichnemmonidacwe seer ener 170
lichietmmonoideaee esse ee ene: 164
ania nee. ctr A tse SELLE,
ILFAHCOR GES skiscedddonubeccacac 192
Macropiddernreer een ee eee
Merachilidaem ee sare cere ecoe
Mecalodontidacieenann eee eerie 155
Mielinmidaesr es Wo05 Ah en vue 22)
Wiretihto cidade ms sem ae 4t te eee oe 207
Miyinanidacige<h ci ote eee ee 183
MIWSROMROGGAS ob: caenecmoccsense 207
Miritillid aes iis ats. Se oe 207
iINomadidacwaseers. reo
INionnitd ae Wee ietise | cra eee MOSS.
INivsSonidaee anemia ace eee ce 216
Oryssidaey aii ae oe 157
Oxy belidaewsns eee eee 217
Pamiinet daeweecmce tn ci or nclO
Relecintdaey sy seein sobee 198
Remphredomidae a5 ne ssede ae a2 ot:
Reitlampidaemnnne ease 191
Rivlanthidaes en pe ereeee 218
PleiingeeIeeienaeie 5 40655 bo oub one 195
Sannin chiaigidaecmee er aert ret 209
IRSenid acta: ao aes ees erate VAY
IAISAO DINOS ssoosacooonccc< 162
Pteromalidadeunre meee en sete 186
Sapycidae Diocese Sonera 206
Scelionidaee yi reeierchncriaey tees: 196
ScolidaGeng sree ee Pre 205
Ser pliidaes sctantar tees 197
Sespiordeagsnn tse ee 195
Sieniphonidaeiers a soe eee 189
Sinicidaepaiserystocae Oni ane: 157
Spalanieidaciasereeeee aoe 187
SplveenGkiS “Ge cdadavcenceoscuses LAY
Sphecoideawyave er nee eee 215
Stelididaee ve acts ee ore Oe
SuepinaimiGAe™ , ceScoacocuccobsbec 167
aventhinedinidaea = ane macoeeec 160
Mentimedinoideass eee ae 152
Metrastichidader: aac oat etek 185
Mrichogramimidaes esses scene 184
IB ovehsnolGe Engg gan eoomioe Shado SNe 187
‘Brisonalidacgyne sce eee esis siete 170
Mirypoxmylomdaes ae eee ec
Mespida ernie. aks sein acre PA
Wiespo1dea: to.. casei cs sores eee 204
WVipronidaer acne one aes aoe 165
XGipliyriidaee ec seer eee ares 158
Xcyeliidia emis a. tate cec eis ree arte 155

Meyhocopidaer sett, vce cos 234

MINNESOTA BARBERRY ERADICATION LAW
GENERAL LAWS OF MINNESOTA FoR 1919
Chapter 81—S. F. No. 120

An act requiring the owner or occupant of premises within this
state, on which Mahoma bushes and Barlterry bushes of the rust pro-
ducing varieties may be grown, to destroy the same, declaring the same
to be a public nuisance; imposing certain powers and duties with refer-
ence to the same on the state entomologist; and providing penalties
for the violation thereof.

Be it enacted by the Legislature of the State of Minnesota:

Section 1. All Barberry (Berberis sp.) bushes and all Mahonia
(Mahonia sp.) bushes except the species and variety known as Japa-
nese barberry (Berberis thunbergit) are rust producing species and are
hereby declared to be, and the same are, a public nuisance and a menace
to the public welfare, and their maintenance, propagation, sale or intro-
duction into the state is forbidden. It shall be the duty of every person
owning, occupying or having charge of any premises on which such
bushes of the rust producing varieties are grown, or at any time found
growing, to forthwith destroy such bushes.

Section 2. The state entomologist is authorized, and it is hereby
made his duty to cause all such rust producing Mahonia bushes or
Barberry bushes within the State of Minnesota to be eradicated. The
state entomologist shall make rules and regulations relating to the most
convenient and expedient method of eradicating and destroying such
rust producing Mahonia bushes or Barberry bushes; he shall have the
power to appoint one or more agents to enforce the provisions of this
act, and he, or his agents, shall have free access at all reasonable hours
to any premises to determine whether such rust producing Mahonia
bushes or Barberry bushes are growing thereon, and to require reports
from the owners or occupants of any premises as to the presence of
such bushes thereon.

Section 3. In pursuance of his powers hereby granted, whenever
the state entomologist, or his agents, shall have found Mahonia bushes
or Barberry bushes of such rust producing varieties on any premises,
it shall be the duty of the state entomologist, or his agents, as the case
may be, to immediately notify or cause to be notified, the owner or
occupant of the premises on which such bushes are growing; such
notice shall be sent to such owner or occupant in such form as the state
entomologist shall prescribe, and if such Mahonia bushes or Barberry

239

240 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918

bushes are not destroyed within ten (10) days after the mailing of
such notice, if sent by registered mail, or within eight days after the
delivery of such notice, if delivered by messenger, the state entomo-
logist, or his agents, shall destroy or cause to be destroyed such Ma-
honia bushes or Barberry bushes. The expense of such destruction
shall be paid to the state entomologist by the owner of the premises
within ten (10) days after the rendition of a bill therefor, and if such
cost shall not be paid within said time the bill shall be reported to the
county attorney, who shall forthwith collect the same in the name of the
state and shall turn the amount collected over to the state treasurer
to be credited to the road and bridge fund of the county.

Section 4. The state entomologist, or his agent, may, or when-
ever requested by any resident of the state, shall determine, or cause to
be determined, whether or not the Mahonia bushes or Barberry bushes
grown on certain premises are of the rust producing varieties. The
said entomologist shall make a certificate of his findings and determina-
tion in the premises, which certificate shall be prima facie evidence
of the facts therein recited. Such certificate may be received in evi-
dence in any civil action arising under the provisions of this act.

Section 5. Any person violating any of the provisions of this
act shall be guilty of a misdemeanor.

Section 6. This act shall take effect and be in force from and
after its passage.

Approved March 21, 1919.

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