3y?)

Nineteenth Report

State Entomologist
of Minnesota

To the GOVERNOR

By A. G. RUGGLES

Agricultural Experiment Station
University Farm, St. Paul, Minn.
December 1, 1922

| ° lof wer i | or f ncagit 3

Nineteenth Report

State Entomologist of Minnesota

TO THE GOVERNOR e/

/
/

By A. G. RUGGLES

SUBJECT INDEX

Page

General report on the activities of the entomologist, including insect conditions
andedstinancialstatement., by. (Gy ug eless-s)-1-.- bers. ie stele el ohelensco eyel= eS

Preliminary report on the life history and control of the potato leaf hopper

Empoasca mali LeB., by A. G. Ruggles and J. R. Eyer...............-- 10

- The red turpentine beetle in Itasca Park by S. A. Graham.................. 15
Effect of physical factors in the ecology of certain insects in logs, by S. A.

(Gant nichgeh saxo or nd tees pe eat oa) ed ails Pree ROME =a Gia ee a ence Ror A BAe Cae oa een Wace ie 22

WMeriiseasr as paresiticide:s yale alesis, Giltriets eer ay te house Sacer eee ee ainda cs eret pho AI
Studies on the life history and biology of Perillus bioculatus Fabricius, includ-
ing observations on the nature of the color pattern (Heteroptera, Penta-

LoOnndae) ie bya attyarlt, micaiolit stcynces cts ela otevons it cetaye ote acl eee ne steal 50

Preliminary notes on the Mutillidee of Minnesota, by Clarence E. Mickel.... 97

- -Synoptical key to the Aphididze of Minnesota, by O. W. Oestlund......... I14

Agricultural Experiment Station
University Farm, St. Paul, Minn.
December 1, 1922

LETTER OF TRANSMIT TALE

q December 22, 1922
Honorable-J. A.©:-Preus, 31
Governor, State of Minnesota,

St. Paul, Minn.

Dear Sir:

In compliance with the law I have the honor to present herewith
a report on the experimental and extension activities of the entomolo-
gist for the years ending December 1, 1921 and December 1, 1922.

Very truly yours,
W._C. CoFFEY,

Dean

Published November I, 1923

December I, 1922
Dean W. C. Coffey,
University Department of Agriculture,
University Farm, St. Paul, Minnesota.

Dear Sir:

In compliance with the law I have the honor to present herewith

‘a report on the activities of the entomologist for the years ending
December 1, 1921 and December 1, 1922. A typewritten report was
given you December 1, 1921, for the year preceding, but as this (1922
*s the year for the report to be printed I am making the report to
cover the two-year period.
The law mentioned states that the entomologist shall make a report
to the governor. As the legislature of 1921 divided my work, placing
the regulatory part under the State Commissioner of. Agriculture and
the experimental and extension part under the University Department
of Agriculture, I have made two reports, that covering the regulatory
phase of the work being incorporated in the biennial report of the Com-
missioner of Agriculture; and the attached report, to be printed as
the nineteenth report of the entomologist, to the governor. These
reports have been the outlet for publishing some very valuable data
on Minnesota insects, and it is believed that the value of the series is
increasing. Many favorable comments have been received from work-
ers in entomology throughout the country as well as from those within
the state. ers,

The legislature of 1894 and every legislature since, appropriated
money for the work of the entomologist directly. Up to the fiscal
year 1921-22 this money has been spent directly by the entomologist.
As the law of 1921 places the responsibility of the work in the two
channels mentioned, the funds are now distributed through the State
Department of Agriculture and the University Department of Agricul-
ture, respectively.

A discussion of the principal insect problems of the biennium and
the financial statement follows:

Insect problems of the biennium

The first year of the biennium 1920-21 was very unusual. The
winter was very mild and consequently more insects than usual were
. able to pass comfortably through the dormant period. This mild winter
was followed by a very early spring and a long warm summer. As
far as insects were concerned conditions were comparable to those

4 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I1Q22

of states much farther south. The usual rigors of our northern winters
and the shortness of our summers prevent many insects from becoming
very serious pests. If 1921-22 had been similar to 1920-21 the great
increase of virulence noted in the summer of 1921 would have reached
serious proportions in 1922. Fortunately the last season returned to
normal and no unusual outbreak occurred.

Corn Ear Worm (Heliothis obsoleta Fabr.)

In 1921 the damage done by the corn ear worm was very severe.
Ordinarily this insect is not a bad pest in Minnesota. In our expert-
mental plot where corn has been grown in some part each year for
seven years, the ears infested have rarely been more than 10 per cent
and usually 5 per cent or less. In 1921 the injury reached 20 per
cent and in some parts of the state much more. Field corn, altho
normally not injured, was seriously damaged. In some cases even the
tassels were attacked before they opened.

The reason for this marked increase in 1921 was probably as
follows: The insect passes the winter as a pupa in the soil and accord-
ing to our experiments, comparatively few survive in Minnesota. Our
infestation comes from moths which fly in from states to the south.
Whether in the winter of 1920-21 more of these pupae survived the
winter or whether more survived the winter in neighboring states, or
whether the moths, on account of the warm spring, were able to start
operations earlier, there was a decided increase which may be accounted
for in one of the ways mentioned. In the summer of 1922 the corn
ear worm infestation was only slightly higher than normal and was
less than 10 per cent in Golden Bantam. The insect will probably not
be serious in 1923.

Unfortunately, no good method for controlling this insect in field
corn has yet, been found. Cultivating the soil as much as possible
after harvest, particularly fall plowing, will help. In small fields of
sweet corn we have controlled the pest by dusting arsenate of lead
directly on the fresh silks, at short intervals over a period of two
weeks. ‘ Experimenters in other states have obtained similar results.

Granary Weevil (Calendra granaria Linn. )

The insects which attack stored grain were unusually destructive
in 1921. The granary weevil, which hitherto had been unknown in
Minnesota spring wheat, was prevalent throughout the southwestern
part of the state. Its general distribution in elevators and granaries
can be accounted for only by the mild winter followed by a long warm
summer. The damage done by the granary weevil was added to by

INSECT NOTES FOR IQ2I-22 5

other insects. The so-called “bran bugs” which are often present in
the state in small numbers were particularly abundant in 1921.

This unusual situation became more complex because recent rul-
ings by insurance underwriters, railroads, and others have prohibited
the use of carbon disulphide. Carbon disulphide has been universally
recommended by entomologists for fumigating infested grain. Much
time has been devoted to the study of fumigants in an effort to provide
the grain growers and dealers with some adequate means of protecting
their grain from these pests.

In 1922 the superabundance of these granary pests decreased, but
the experimental work on fumigants is siill being carried on vigorously
under the direction of Dr. R. N. Chapman. Preliminary work indicates
that in normal years elevators and granaries can be kept free from
granary weevils and bran bugs by so handling the grain that the tem-
perature is kept at or below the freezing point. If the grower would
grade and clean his grain during the first cold snap of the fall it
would seem that he would have very little trouble from these pests.

Potato Leaf Hopper (Empoasca mali Le B.)

- Probably the insect about which the most complaints were made
in 1921 was the potato leaf hopper. It has been in the state for many
years, but it is only in particularly dry seasons that it seems to do
serious damage in Minnesota. In 1916 a very bad outbreak 6ccurred,
but at that time the seriousness of the pest was not thoroly realized
and its connection with “hopper burn” not fully recognized. ° S. Marco-
vitch, working with this insect here at that time, was convinced of
its seriousness and its relation to hopper burn, and published his con-
clusions in the local press. Between 1916 and 1921 there were no
serious outbreaks in this state, but in 1921, taking the state as a whole,
this leaf hopper was responsible for a 25 per cent damage. In 1
this damage was equally severe.

In our experimental plots where different liquids and dusts were
tried, liquid bordeaux mixture (4-4-50) applied at 175 pounds pressure,
three nozzles to the row, and applied three times during the season
gave good control. No other spraying compound was nearly as effec-
tive. This again bears out our recommendations of several years ago,
advocating high pressure and better sprayers.

Grasshoppers

In 1921, Minnesota was threatened with a grasshopper outbreak.
Fortunately a wet June in the infested areas caused the death of most
of the young hoppers. In Kittson County one large area was infested

6 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

but the prompt action of the county agent in organizing the farmers
and ge‘ting them to spread the poison bait of bran and arsenic stopped
the invasion at the outset. Grasshoppers were reported doing damage
around Grand Rapids on the edge of the Iron Range, but the injury
did not prove serious. From specimens obtained the principal depre-
dator here was Melanoplus bruneri Scudder, a species never previously
reported as doing damage in Minnesota.

In 1922 no reports were received of damage done in the state by
erasshoppers.

Hessian fly (Mayctiola destructor Say )

For some unknown reason fhe hessian fly has done no serious
damage in Minnesota for many years. In 1922, a field of winter wheat
near Waconia was badly injured by this pest. It is too early to say
whetker the insect has obtained sufficient foothold to continue its
depredations.

The best preventive remedies are plowing under stubble as soon
after harvest as possible, keeping down volunteer wheat, rotation of
crops, and in the case of winter wheat, sowing as late as possible, not
before September 2

Chinch Bug (Blissus leucopterus Say )

In Minnesota fifteen and twenty years ago innumerable chinch bugs
destroyed the grains and corn. Since 1908 there has been no authentic
record of this insect being present in the state. In 1922 some specimens
were sent in from the northern part of the state. We were unable
to find, however, that they had done any damage. The last two seasons
Fave been very favorable for their reproduction, being hot and dry,
and therefore this insect may again become a serious pest in the near
future.

Apple Maggot (IRhagoletis pomonella Walsh)

One of the pests that has given much trouble is the apple maggot
or railroad worm. This was first found in Minnesota orchards in
1919. At picking time very little notice is taken of the work of the
insect, but soon after the apples are placed in storage complaints begin
to come in. The real orchard grower is awake to the difficulty but
the small grower and the farmer with a small orchard do not appreciate
the damage until they begin to use the stored fruit. One small grower
in 1922 harvested his fruit and put it away in the cellar. A few weeks
afterward. he was unable to find a sound apple in his crop of 60 bushels.

INSECT NOTES FOR IQ2I-22 7

Our experimental work has shown that spraying with arsenate
of lead at the usual rate about the middle of July and again the first
week in August, if the insect is abundant, will control the pest. These
sprayings of course are in addition to the regular sprayings, the last
of which is usually given the third or fourth week of June.

Oyster Shell Scale (Lepidosaphes ulmi Linn.)

The oyster shell scale is becoming more and more abundant in
southern Minnesota. Several orchards were studied in 1922 which
were badly injured by this pest. Some owners are taking vigorous
steps to control the insect. The dormant lime-sulphur spray applied
as late as possible in the spring, or a miscible oil, will soon put ihe

insect under control.

Asparagus Beetle (Crioceris asparagi Linn.)

The asparagus beetle, found for the first time in the state in 1919,
continued to spread. In 1922 it was found in the valley of the Missis-
sippi, having spread from the St. Croix where it was first found.

Several other insects were unusually abundant in 1922. The
American sawfly (Cimbex americana Leach) and the red-necked cane
borer (Agrilus ruficollis Fab.) were plentiful at Lakeland. The phlox
bug (Lopidea davisi Knight) is proving a serious pest in two different
localities, Mantorville and Winona, in southern Minnesota, and the
plum gouger (Anthonomus scutellaris Lec.) was reported very com-
mon at-La Crescent. A new record for the dark apple red bug ( Hetero-
cordylus malinus Reut. was obtained in 1922. It is possible that this
may prove one of the serious recent introductions. +

Spruce Budworm (Harmologa fumiferana Clem. )

The spruce budworm has continued its destructive work in the
coniferous forests north of Lake Superior. Investigations concerning
its activities were carried on and an extension bulletin on the subject
was published.

Forest Tent Caterpillar (Malacosoma disstria Hbn.)

The forest tent caterpillar has been responsible for considerable
damage in several districts of the state. It was particularly abundant
in the Lake Park region where considerable areas of hardwoods were
defoliated. In this region the caterpillars were heavily parasitized and
the outbreak appears to be on the wane. Apparently this insect is
becoming increasingly abundant in the aspen forests of the north and
promises to be an important factor in the forest economy of that regior

8 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

Jack Pine Sawfly (Diprion abietis Harris)

Many reports of injury to Jack pine by sawfly larvae were received
during the season of 1922. The species responsible was not the com-
mon pine sawfly but the fir sawfly (Diprion abietis). Several localities
were examined where the trees were completely defoliated by this insect,
and judging from reports received from other places not visited, injury
occurred locally throughout the Jack pine region. Owners of summer
hotels and cottages are urged to plant other species of trees and develop
mixed woods about their property. This will tend to reduce the likeli-
hood of a sawfly outbreak in these places, where the esthetic value of
the trees is paramount.

Birch Skeletonizer (Bucculatrix canadensisella Cham.)

In August and early September of 1922, the birch skeletonizer
destroyed the leaves in practically all the birch woods in the northern
part of the state. This defoliation came after the trees had completed
the season’s growth and did comparatively little permanent injury.
In some cases, however, owing to the early loss of leaves and the
late fall, the buds of the birches began to swell before cold weather
set in. This will probably mean a considerable amount of winter
injury. The larvae of this insect were so abundant that there was not
sufficient green foliage to carry them all to maturity. A very large
proportion of the caterpillars starved to death and many others spun
cocoons in an under-nourished condition. As a result it is probable
that the skeletonizer will not be very abundant in 1923.

Many other insects were reported and many letters were written
answering inquiries, but these mentioned were the most important.
Spraying

Experimental work in spraying orchards, comparing the regular
formula of arsenate of lead and lime-sulphur with dusts, has been
continued. Dust versus liquid sprays js a very live question with
the orchardist as well as with the potato grower. The importance of
spraying is being more and more recognized by the grower in this
state and it 1s necessary that the different formulae be tried under
Minnesota conditions. So far the dusts have not proved, either in
results or costs, any better than the liquid formulae advised for several
years, viz., arsenate of lead and lime-sulphur for orchard spraying,
and arsenate of lead or calcium arsenate plus bordeaux mixture for
potato spraying.

FINANCIAL STATEMENT IQ2I AND 1922 9

Except where the oyster shell scale or an abundance of plant lice
eggs are present, a dormant spray of lime-sulphur is not advised.
‘The financial statements for July 1, 1920 to July 1, 1921, and
July 1, 1921 to July 1, 1922, are appended.
Respectfully submited,
A. G. Ruggles,

Entomologist.
FINANCIAL STATEMENT
Fiscal Year, July 1, 1920, to June 30, 1921
SGDDTROSDITB I DV val Si age 5 Aa) alle Pi ania cal eae pee Oh aia ah ere RE $6,300.00
rie batanceer ss aniis Sars ves ce cee ee ss ete eth: AE See Gere eee 404.19
$6,704.19
Expenditures
Bee Regret eta heya iste oe eas oe ies Shame eh $3,720.95
Bibeln lity Fae EXAM EISE SM ere cycles, «ope ccc totorne ous sl ore Seles Bee 530.61
Pecia ine am UDIISINNO N.S catia cdicleciws ot e'v.nedadie sas 812.35
ICES Phe strtae peice ec ee cis noe oie siete ete Felons 19.80
Epined arti N ts SEP SG yore a ire wires citvarei Rartra ciate woekincsts iets oe ale 27.56
WLS a SGT RS) 1 CN SSE ee aera eA a ae Ge Ee 440.56
PeECS ACHES, clit EQUMPITICNE S 4 06 sceciess os bade eWiadled Velsaes 108.23
PEMaIITIES ANG -COUIPINEME 2. soelc<.oce-c # vielsmicwe «8 oe eee oe 1,040.64 6,700.70
BAS IPA AREXS)— ets ety aaah erty eh a A Scere A a AARP ey $3.49
Fiscal Year, July 1, 1921, to June 30, 1922
JASTISUAS /DV8 ZirT Cm Ears ee cro ae Se ese $5,000.00
Expenditures
SUE ESM ee erent Lie eterc ara ire eee RE os eae Les $4,342.11
SAV CIM MEX PENSESE ate aioe cs see cat ek noite ont tie mee 408.96
rere A ROMER ELESS eS oes fc Sek «Se cae cd Oe cic vines ueeha 8.36
IES S gh) SHI O fs SS SR ae ae aS ate ee 53.88
Piemitiber anGee QUpMentrc.. cas) << ses tbs ale tes See 18.75 4,832.06

| SYELLGWEV GI” che Sec em At Opa a an ara eee gr ; $167.94

PRELIMINARY NOTES ON THE LIFE HISTORY AND
CONTROL OF THE: POTATO LEAE-HOERIR:
Empoasca mali LeB.*
by
A. Gz RUGGEES AND. Js Ke Dyer
Life History

Food plants—The food plants of the potato leaf-hopper as de-
termined from observation at University Farm in 1922 are potato,
apple, box elder, blackberry, raspberry, curly dock (umes crispus L.),
rhubarb, and dahlia. Development of the first brood takes place almost
exclusively on potato, while the second brood may develop on any
of these plants, altho potato is preferred. The adults feed indiscrim-
inately on all these food plants when potato is not available.

Overwintering -adults——Observations on the overwintering habits
of the potato leaf-hopper in Minnesota showed that only the adult
stage survived the winter. In 1922, following a heavy frost on
October 12, adults began to leave their food plants to hunt for hiber-
nating quarters. They had completely disappeared from the fields by
November 15. Individuals feeding on potato in the greenhouse left
the plants at approximately the same date and hibernated beneath dead
vegetation and flower pots. In 1922, adults began to come out of
hibernation the latter part of May and to feed on box elder and black-
berry. They were first observed on early potatoes June 7 and became
quite abundant about the middle of the month.

First generation.—Small numbers of eggs were found in the stems
and midribs of potato leaves about June 12, increasing in abundance
toward the latter part of the month. The nymphs hatching from these
eggs required an average of twenty days for development, changing
to adults late in July.

Second generation—The adults of the first generation became
most abundant in August and lived from 25 to 50 days. The egg
laying of these adults was continued from the latter part of July until
early October.

The nymphs hatching from these eggs required about 30 days
for development. Those hatching late in September did not develop

1 Published with the approval of the director as Paper No. 390 of the Journal Series
pf the Agricultural Experiment Station.

PRELIMINARY NOTES ON POTATO LEAF-HOPPER Il

so rapidly, however, and were killed by freezing weather before ma-
turity. The adults of this generation fed on potato until. the plants
were killed by frost and then migrated to other food plants, where

they fed until hibernation.

Control

Experiments were conducted during 1922 to determine the value
of spraying and dusting with various compounds for the control of
this insect. Tenth-acre and one-acre plots of Bliss Triumph and Green
Mountain potatoes were used in order to test the same materials on
an early-maturing and a late-maturing variety. These fields were
planted in duplicate, each set receiving applications of the following
materials :

Liquid bordeaux mixture
Liquid bordeaux mixture and Black Leaf 40

Black Leaf 40 alone

Dosch copper calcium arsenate dust

Dosch copper calcium arsenate and nicotme dust
Nicotine dust alone

When no arsenical was in the mixture an application with an
arsenical was made when needed to take care of the Colorado potato
beetle. All sprays were applied with a Friend power sprayer using
a four-row, 3-nozzle-per-row boom, and dusting was done with a
Niagara power duster.

Times of spraying.—All plots received four applications of liquid
or dust material at intervals of about two weeks. The tenth-acre plots
were first sprayed and dusted on June 24, when the potato plants were
about six inches high. Subsequent applications were made on July 7,
July 25, and August to. The Bliss Triumph plants were mature at
the time of this last spray and died soon after; the Green Mountain
plants remained green until frost. The acre plots were sprayed on
June 29, July 14, July 27, and August 18, and remained green until
the first of September. The tables show the results of these tests.

During the course of these spraying experiments accurate counts
were made in the various plots of the percentage of foliage injury,
and the average number of hoppers per plant. The results gave some
idea of the relation of the hoppers to the percentage of injury and of
the efficiency of the spray materials used. |

On the early maturing variety, leaf-hoppers occurred in greater
abundance over a shorter period of time. The percentage of injury
during their maximum feeding period was approximately the same
on both varieties.

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PRELIMINARY NOTES ON POTATO LEAF-HOPPER 13

PAGE SpleELDy PLAN AND RESULTS OF _POTATO: SPRAYING

EXPERIMENTS ON ONE-ACRE PLOTS AT GRISWOLD
FARM, MINNESOTA

No. and date Yield in bu.
Variety _of applications Materials le) pemacre
Bliss Triumph I-June 29 | Liquid bordeaux mixture 4-4-50
2-July 14 and lead arsenate 2-50.......... 273
3-July 27
4-Aug. 18
Bliss Triumph As above Liquid bordeaux mixture 4-4-50
and Black Leaf 40, 1-800 and
leadvarsenater2=50n osc tsa mentos: 337
Bliss Triumph 1-June 30 | Dosch 13-8-79; copper calcium
2-July 14 ARSeNaLew GtShs .ccratcoarow se eae 185*
3-July 27 ~
4-Aug. 18
Bliss Triumph As above Dosch 13-8-79; copper calcium ar- |
senate dust and Dosch 2-4%
Micotime Mller usta. sien eee «> 201*
Bliss Triumph I-June 2 Inter-series check, between dusted
2-July 14 and sprayed series, lead arsenate
. 3-July 2 PIAA Aes HEA IC Beto 193
4-Aug. 18
Bliss Triumph 1-June 30 | Isolated check, lead arsenate, paris
2-July 14 Sreeme Mime 7-1-40ee sos. wel: 152*
Se 3Iuly 27
4-Aug. 18

* Yields slightly influenced by outbreaks of Colorado Potato Beetle.

Liquid bordeaux mixture markedly decreased the number of leaf-
hoppers and the percentage of foliage injury in both varieties. The
addition of nicotine was followed by a greater decrease in the number
of hoppers, but additional lessening of foliage injury was only notice-
able in the early variety. In the dusted plots, the number of hoppers
and the injury were lessened, but these decreases were not so con-
sistent as in sprayed plots and require further experimental evidence.
Nicotine used alone, in dust or liquid form, produced small decreases
in both number of insects and injury.

It will be seen that liquid bordeaux mixture gave good control
against the leaf-hopper in every plot where it was applied, the yield
being decidedly better than in the check and dust applications. In the
tenth-acre plots no advantage was gained by adding the nicotine solu-

I4 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

tion to the bordeaux mixture, but in the acre plots a decidedly better
yield was obtained. Further experimental evidence should be obtained
in 1923.

It will be seen from the tables that bordeaux dust, whether applied
alone or in combination with a nicotine dust, gave no appreciable results,
in each case the difference between the yield in check plots and in those
where the dusts were used being approximately the same, or at least
within experimental error.

RiP “PURE DN PINE) BEE TEERSEN: LTASCA PARK?

By S. A. GRaAnAM

Injury to trees by the red turpentine beetle, Dendroctonus valens
Lec., has usually been considered of secondary importance and reports of

rh

outbreaks in standing timber are very rare. These occasional outbreaks
have usually followed immediately after the conclusion of logging
operations. In Itasca Park, however, this beetle has been very abundant
and was apparently responsible for a considerable amount of injury to
green trees. Norway pine, Pinus resinosa Aiton, was the species attacked
most frequently. It was not at all uncommon to find groups of appar-
ently healthy trees with from one to a dozen Dendroctonus pitch tubes
about their bases. A large percentage of dead trees showed signs of
Dendroctonus work and from general observation it might easily have
been assumed that many trees were being killed by this insect. In the
course of an improvement cutting carried on during the winters of
1920-21 and 1921-22 the work of these beetles was very apparent. In
one area 30 per cent of the trees removed were infested.

Many apparently healthy trees showed signs of Dendroctonus work.
In many cases these trees were of particularly great esthetic value and
their cutting meant*a considerable loss. This situation gave rise to
two very pertinent questions: (1) Would these infested trees succumb
to the attack of the beetles? (2) Was their presence a menace to the
adjacent timber? The future policy to be followed in handling the
standing timber in Itasca Park hinged to a considerable degree upon
the answers to these questions.

Therefore, with the aid of the State Forest Service, the Division
of Entomology undertook the task of investigating the activities of
the red turpentine beetle in Itasca Park. The problem resolved into
an ecological study of the beetle and was naturally divided according
to the locations in which the beetle might be found as follows:

1. Breeding 1m living trees

2. Breeding in fresh stumps
3. Breeding in freshly cut logs
4. Breeding in slash

The Red Turpentine Beetle in Living Trees
In studying the effect of the beetle upon living trees the sample
plot method was used in collecting data. Forty-five plots were laid

1 Published with the approval of the director as Paper No. 392 of the Journal Series of
the Agricultural Experiment Station.

16 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

out in different parts of the Park in stands representing as wide a
range of site conditions as could be found in the region under observa-
tion. The plots were almost all two-tenths acre in area, but in a few
cases it was found advisable to make them smaller, and then one-tenth
acre was adopted as the unit area.

Each tree in every plot was carefully examined for evidence of
beetle attack. The litter was scraped away from the base of each tree,
exposing the mineral soil, so that the location of all tunnels, both old
and new, could easily be determined. Records for each plot were kept,
showing in addition to the amount of infestation, the exposure, the
size of trees, the condition of undergrowth, the number of trees per
acre, and the presence of old or new cuttings near the plot.

Considering Itasca Park as a whole, the infestation as indicated
by these plots was much lighter than the data gathered in connection
with the improvement cutting of 1920-22 would lead one to suppose.
Of the 45 plots, 8 showed no sign of infestation. On more than
two-thirds of the plots the infestation was Io per cent or less. On
only four plots did the infestation exceed 25 per cent. On only one
plot did every tree show signs of beetle work. In every instance where
the infestation exceeded 25 per cent, freshly cut logs had been held
over the summer season in the immediate vicinity of the plot.

Table I. Percentage of Infestation in Standing Norway Pine

Distance from logs

Location a
Less than 100 yds. 200 yds. 400 yds.
OldMimnillecsite = verrnien o- 100 52 8
Nicollet*cabin {7 5-cyei eens: 66 21 Gi
SW% of SWY Sec. 3... 23 12 9

The distribution of beetles as shown by sample plot studies proved
without doubt that the infestation of green trees is correlated with the
presence of green logs, fresh stumps, lightning-killed trees, or windfalls
in the immediate vicinity. Apparently the beetles are also attracted
to freshly burned areas, and as a result uninjured trees along the edge
of a burn are likely to be more heavily infested than trees farther away.

The abundance of infested trees immediately around the old mill
site southeast of Mary Lake illustrates well the conditions usually
found where freshly cut logs are piled near green trees during the
growing season. On the plot nearest the mill 100 per cent of the
trees showed evidence of beetle work. The amount of infestation
diminished rapidly as the distance from the mill site increased. At

RED TURPENTINE BEETLE IN ITASKA PARK Wi

two hundred yards the infestation dropped to 52 per cent and at four
hundred yards to 8 per cent. Similar conditions existed at Douglas
Lodge, where unpeeled green logs for cabin construction were left
piled in a Norway pine grove during the summer.

In the SW% of the SW% of Section 3, where logs were cut for
cabin construction in 1920 and left piled for some time, 23 per cent
of the trees near the piles were infested. Other plots in the area from
which the logs were cut showed an infestation of 9 per cent. Within
500 yards from the cutting, the infestation was reduced to zero. At
Nicollet cabin the infestation next to the cabin was 66 per cent,
at two hundred yards 21 per cent, and at four hundred yards 7 per cent.

The greatest infestation was always found about spots where logs
had been piled, but a very decided relation was also observed between
the presence of stumps and beetle infestation. Where there were
stumps the trees in the vicinity were always more or less infested.
The time of greatest beetle infestation appeared to be the second sea-
son after the trees were cut. As a rule the infestation near stumps
did not exceed 10 per cent.

TABLE IJ. INFESTATION IN DIFFERENT PARTS OF ITASCA PARK

Location No. plots Stumps Percentage Norway pine infested
La Salle Trail 2 Present 14
Cabin Log Trail Sec. 3 6 Present 12
Cabin Log Trail Sec. 3 3 None o (No recent cutting near)
Old mill site 3 Present 53 (Beetles attracted by green logs)
East of Mary Lake 3 Present 8
Nicollet cabin 3 Present 31 (Beetles attracted by green logs)
Kelley Trail 2 Near 3
Bohall Lake 2 Present 10
NEY Sec. 15 I Present 30
Garrison Pt. 2 Present 11 (All tunnels very old)
Forestry School 2 Near 6
Pritchett’s Grove 2 None 5 (All tunnels in burned trees)
Preacher’s Grove 5 None 6
Near Peace Pipe Springs 1 None )
De Sota Cabin 2 None 3 (in path of 1913 fire)
Ockerson Heights 3 Near 6
Budd Lake I Near 6
East of S.W. cabin 4 None 9 (Edge of burn)

Windfalls and trees injured by fire also appeared to attract the
beetles. When a windfall lay against the base of a standing Norway
pine the standing tree was almost always infested. Wherever the

18 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

forest was undisturbed by cutting, windfall, lightning, or fire, beetle
infestation was seldom found. Without exception all of the nine
uninfested plots were so located.

3efore this study was undertaken, it was suspected that site con-
ditions, density and composition of stand, age and size of trees, density
of underbrush, and other such factors might have some influence in
determining the extent of beetle infestation, but no such relation ts
apparent. The examination of the sample plots, however, does demon-
strate conclusively a specific relationship between infestation of stand-
ing trees by the red turpentine beetle and the presence in the immediate
vicinity of green logs, fresh stumps, windfalls, or injured trees.
Doubtless the beetles are attracted by this freshly cut or iniured
material.

Naturally, where so many trees were infested, as indicated by the
data gathered on the sample plots, one might expect a considerable
number of trees to succumb to the beetle attack. Such an assumption,
however, did not prove to be true. Strange to say, not a single tree
was killed by the beetles on any of the plots examined. In one case a
tree was attacked so heavily that its death was probably only a ques-
tion of time, but it was still alive when examined. ‘The only tree
observed that was without doubt killed by this beetle was a large
Norway pine, standing alone near the mill site referred to above. This
tree had been attacked at fifty-three separate spots about the base. Brood
had been reared in only three of these tunnels. Another large tree
near was spotted about the base with forty-five pitch tubes. No brood
had been reared in any of the tunnels, and the tree was apparently
perfectly healthy and growing normally.

It was exceedingly rare to find any brood emerging from infested
living trees. Usually the adult beetles tunnelled into the tree and, after
a longer or shorter battle with the flow of resin, they were either over-
whelmed and drowned or were forced to leave. From this it would
appear that the beetles attacking living trees are either misguided
individuals whose instinct leads them to impossible breeding grounds,
or they are the overflow which can not be accommodated in the avail-
able material suitable for breeding.

In this connection it must be remembered that all the dead trees
on much of the area studied were taken out in the course of the im-
provement cutting mentioned. Much of the evidence of past beetle
work had been removed before this study was undertaken. Therefore
this report describes conditions only as they exist at present! “tas
certain that with the passing of logging operations in and about the

RED TURPENTINE BEETLE IN ITASKA PARK 19

Park the number of turpentine beetles has been much reduced. A
few years ago, during their flight, these beetles were so abundant
that hundreds could easily be collected as they rested on the screens
of porches, doors, and windows. Last year very few were observed
on the screens.

Red Turpentine Beetle in, Green Logs and Slash

From the considerable infestation in living trees standing near
green logs it might naturally be assumed that such logs would pro-
vide a favorite breeding place for the beetles, but this did not prove
true. In the course of the work many logs, broken butts, and slash
piles were carefully examined. Never was any sign of turpentine
beetle work seen in slash piles or in any part of the tree which came
from a point higher than six or eight feet above the ground. Only
butt cuts were found infested, and in these the stump end was always
most heavily attacked.

Usually the infestation even in butt ends was light, but occasion-
ally a log was found that was particularly attractive to the beetles. In
one such instance the bark was entirely loosened from the wood and
when stripped off a mass of almost full grown larvae was disclosed.
Even with a mortality of 50 per cent during the pupal stage, at least
five thousand beetles would have come to maturity in this log. But
for this one heavily infested log, dozens were examined containing
few or no beetles.

In connection with other experiments in Itasca Park where hun-
dreds of green logs have been used, it has been extremely unusual to
find these logs attacked by the turpentine beetle. Therefore, in spite
of an occasional heavy infestation such as that mentioned above we
are forced to conclude that logs as a general rule do not furnish the
best breeding place for these beetles. It seems probable that the
infestation of trees standing near green logs is not due to beetles emerg-
ing from these logs but to beetles attracted to the spot by the presence
of freshly cut material. Once there they attack the trees.

A comparable instance of this sort of attraction may be cited in
the case of Hylurgops pinifex Fitch. This species is strongly attracted
to freshly cut pine either with or without bark. It is not at all uncommon
in the spring to find bundles of green pine lath filled with beetles of
this species. Sometimes more than one hundred individuals have been
found in a single bundle.

The favorite breeding place of the red turpentine beetle proved

to be freshly cut Norway pine stumps. Fresh stumps were almost

20 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

always found infested, sometimes heavily infested, and it is beyond
question that a large proportion of the turpentine beetles in Itasca
Park breed in them. Examination of a series of stumps cut in the
winter of 1921-22 showed an average of 1.6 tunnels per stump for
White pine and 13.5 for Norway pine. Summer-cut stumps of Nor-
way pine averaged 6.8 tunnels. Brood was reared successfully from
the majority of these tunnels.

In connection with the 1921-22 improvement cutting, an experi-
ment was carried on to determine the effect upon insect infestation of
barking and scorching stumps. One set was barked down to the ground
line; one set was scorched by burning either slash or dry wood over the
stump; and a third set, kept as a check, was untreated. The results
of this experiment are shown in Table ITI.

TABLE III. INFESTATION OF NORWAY PINE STUMPS

No. of new tunnels per stump

Time cut Treatment Maximum Minimum Average
Winter Untreated 27 O Tees
Summer Untreated ASU 0 6.8
Winter Barked when cut 34 te) 127i
Winter Burned when cut 6 O PS

The barking and burning operations were both carried out care-
fully and a much better job was done than could be expected under
ordinary woods conditions. Owing to the frozen condition of the
ground it was impossible to bark below the surface of the litter. As
the beetles tend to concentrate in the lower portions of a stump and
frequently enter below the litter, barking did not have any material
effect upon the number attacking the stumps. Therefore, if barking
is to be effective, it should be done during the summer following
logging. Thoro barking could be cheaply accomplished at that time
and the broods of beetles in the stumps completely destroyed. Even
winter burning did not entirely prevent infestation. However, the
number of beetles per stump was very materially reduced by the treat-—
ment. It was found that burning must be thoroly done to be effective.
Little good resulted when the slash was piled over the stump and
burned. It was necessary to get a good fire all around the stump with
dry material and then pile on the slash a little at a time, keeping the
fire against all parts of the stump. Slash burned over a stump did little
but scorch the upper parts. The cost of barking was not excessive, being

RED TURPENTINE BEETLE IN ITASKA PARK

approximately 314 cents per stump. Burning was slower and _ the
cost therefore ran up much higher, being over 26 cents per stump.
These figures are on the basis of $3 a day.

Conclusions

Altho the red turpentine beetle is abundant in Itasca Park and is
attacking many living trees, it is responsible for the death of very
few. Almost never is brood successfully brought to maturity in living
trees. The infested trees are always found associated with fresh
stumps, green logs, windfalls, or burned areas, the beetles being at-
tracted by the freshly injured wood just as Hylurgops pinifex is at-
tracted to freshly cut pine lath. With the reduction in the logging
operations in Itasca Park the number of beetles and consequently the
amount of infestation will gradually be reduced.

The beetles breed abundantly in fresh stumps and to a lesser

extent in logs. They are never found in slash, as they apparently
confine their activities to the parts of the tree near the ground. Ex-
periments in barking and scorching stumps were effective only when
the treatment was carried down to mineral soil. When the ground
was frozen, it was difficult if not impossible to bark low enough on
the stump for effective results, therefore the early summer months
following logging appear to be the ideal time for this work. Burn-
when thoroly performed, was more effective but expensive.
This study opens up the general question of the treatment of
stumps and waste materials for preventing the breeding of injuriou:
insects. It is evident from the results obtained that even tho stumps are
barked at the time of cutting they may still be a menace. Further work
should be carried on to detemine conclusively what methods can be most
economically employed in handling logging debris, including stumps,
slash, broken logs, and butts.

ing

Ss:

EEPFECT. OF PHYSIGAL FACTORS ING DHE COEOGX= Oe
CERTAIN INSECES IN=LOGS*

By S. A. GRAHAM

The study of forest entomology, like that of almost every branch
of the biological sciences, was first based upon purely empirical knowl-
edge of the insects concerned. The forester learned by experience
and superficial experimentation how the pests of trees lived and repro-
duced, and how they could be controlled.

In Europe, where labor was cheap, there were developed many
mechanical methods of forest insect control such as trapping and other
devices for collecting injurious species, poisoning, and banding. In
America such means as these have proved too expensive and difficult
of application for general use, since the margin of profit in growing
trees for market is small and requires that the expense of all the
operations involved in producing a crop of timber be reduced to the
minimum.

For this reason we must turn our attention to the development
of natural methods, where the elements of the environment are so
balanced as to reduce the probability of extensive outbreaks of injurious
pests. The working out of natural control methods is much more
difficult than the more obvious artificial methods, but it has the decided
advantage of reducing the danger of insect loss to a minimum without
materially increasing the cost of producing timber. The insect control
plan will, under this system, be included in the silvicultural procedure
set forth in the working plan.

When we come to formulate satisfactory methods for the silvi-
cultural control of forest insects, we soon find that empirical knowledge,
superficial experimentation, and general observation do not form an
adequate foundation upon which to build. We can not construct a
substantial superstructure upon a foundation not based upon the funda-
mental laws which govern insects activities. We must not only know
the life cycle of the insects, as it is ordinarily determined by cage
experiments, but we must also know how they react to the varying
conditions of their environment and how they are affected by the
other living organisms with which they come in contact. Thus the

* This paper is a summary of a thesis presented in partial fulfilment’ of the requirements
for the Degree of Doctor of Philosophy, University of Minnesota. The original thesis is
filed in the Library of the University.

Published with the approval of the Director as Paper No. 389 of the Journal Series of
the Minnesota Agricultural Experiment Station.

EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 23

development of methods for forest insect control resolves itself into a
study of the ecological relationship of insects in the forest envirnoment.

The first single factor of the environment to attract the attention
of entomologists was temperature. Several more or less successful
attempts were made to correlate variations in the length of the develop-
mental period and the geographic distribution of animals on the basis
of this factor alone. Judeich and Nitsche (1895) report a rather
unsuccessful attempt of Forester Uhlig-Therand to correlate the length
of the life cycle of Ips typographus Linn. with temperature by compar-
ing with the length of the insect’s life cycle, the total midday tempera-
ture and the total mean daily temperature, as computed from three
readings a day. Merriam (1808) established life zones on the basis
of the sum of positive temperatures (above 43 degrees Fahrenheit for
the entire season of growth and reproduction) which, he believed,
limited the northward distribution of terrestrial animals. The southern
limits of distribution he believed to be governed by the mean tem-
perature during the hottest part of the year. Sanderson (1908) points
out that low winter temperatures limit the northward distribution of
many insects, since many species do not occur in every locality where
the sum of positive temperatures is sufficient for their development.
He also points out that the effective temperature may vary with differ-
ent insects. Later, Sanderson (1910), in a paper treating of the effect
of temperature on the growth of insects, recognizes the importance
of humidity in influencing the rate of development.

More recently Sanderson and Peairs (1913) published results
showing that the variation in velocity of development at different con-
stant temperatures within normal limits was, other things being equal,
increased directly as the temperature, the curve for the increase being
a true mathematical hyperbole. “The factor, or index of development,
for any point on this curve is the reciprocal for the point. Thus the
reciprocal, . . . takes by definition the form of a straight line;
the inclination of this line to the axes of the curve being governed by
the rapidity of development of the insect and stage.” In this’ way it
is possible to compute the complete development curve by establishing
any two points on the curve and plotting the reciprocals.

The first extensive investigation of temperature and humidity as
applied to forest insects was that of Hennings (1907-10), who pub-
lished a series of articles on the biology of certain bark beetles. His
results were based upon experiments under controlled conditions of
air temperature and humidity. His work has materially contributed

24 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

toward the clearing up of some of the controversies arising from con-
flicting observations of authorities. He shows conclusively that the
activities of insects are not governed by temperature alone but that
humidity plays a very important modifying role.

More recently the work of Pierce, Shelford and his students,
Headlee, and others has further emphasized the importance of humidity.
Huntington in his recent book has attempted to show the effect of
temperature and humidity upon man. In the United States very little
has been produced which bears directly upon the effect of physical
factors of the environment upon forest insects. Hopkins (1919-20)
in his attempt to formulate and apply the so-called “‘bioclimatic law’”’
to the activities of forest insects has taken a step in the right direction.

Craighead (1920) working primarily with ash logs in several
localities in the South, found that the temperature beneath the bark
of logs lying in full sunlight frequently reached a point above the
fatal temperature for wood-boring insects. On the basis of his findings
he recommends the weekly turning of logs to protect them from injury
by wood-borers. Even more recently Craighead (1921) has published
the results of a series of experiments concerning the fatal temperature
of the red-headed ash borer with special reference to the effectiveness
of dry kiln temperatures in destroying these insects. He shows that
the fatal temperature varies with the amount of moisture present.

Studies of the nutritional requirements of insects have opened up
a field of investigation. The food factor appears to be extremely impor-
tant in regulating the activities of all insects, and particularly those
that live upon such materials as wood. Baumberger (1919) has shown
that Drosophila is very largely dependent for its successful develop-
ment upon the microorganisms working in its food. In sterile media
the development is very slow or even impossible, whereas in the presence
of microorganisms normal development takes place. He refers to
the work of Haberland (1915), who has shown that the protein content
of trees is very low except in the cambium and phloem, while the
carbohydrate content is high. As a result of this condition we find
in sound green logs that the rapidly developing insects work in the
cambium or in the outer sap wood, whereas the insects which penetrate
the heart wood are usually much slower in their development. Some
wood-boring species are unable to live in wood in the absence of the
organisms producing decay.

For the sake of brevity no attempt has been made in the above
review to mention all the literature contributing to our knowledge of
this subject. The only aim has been to give a general idea of the

EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 25

status of those problems dealing with the effect of the external factors
upon insect activity, and it will therefore be necessary from time to
time to refer to other works not previously mentioned.

Most of the data included in this thesis were collected during
the summer of 1920 at the field station of the University of Minne-
sota Forest School. The prosecution of the work has been materially
aided by the laboratory and other facilities provided by the School
of Forestry and the helpful suggestions and criticisms by members
of the University staff, particularly Dr. R. N. Chapman, under whose
direction the work was carried on.

The study of insects in their natural environment calls for a
careful study of the environmental factors as they exist in nature.
Under controlled experimental conditions it is possible to study very
accurately the influence of a single factor upon insect activity by keep-
ing uniform all but one of a series of factors. By varying this factor
its influence upon the insects under experimentation may be deter-
mined. Such a study under natural conditions, however, involves the
accurate measurement of individual factors or groups of factors such
as light, temperature, humidity, and evaporating power of the air, and
the condition of the nutritive medium.

Experimental Method

In this investigation five species of logs were used. These were
White pine, Pinus strobus, Linn.; Norway pine, Pinus! resinosa Aiton;
Jack pine, Pinus banksiana Lambe; Black spruce, Picea mariana Brit-
ton Stearns & Poggenberg; and balsam fir, Abies balsamea Miller.
The logs were cut into four-foot lengths and placed in a north and south
direction with the north end slightly raised. Representative logs of
each species were placed under lath shades so constructed as to cut
off three-fourths, one-half, and one-third of the direct solar radiation.
One set of logs was left in full sunlight. The methods employed in
supplementary experiments will be described as the results are pre-
sented. The principal factors considered in this work were light,
temperature, evaporation, and relative humidity.

The measurement of light is always attended with considerable
difficulty. Really accurate methods of light measurement are too
complex and difficult for general field use, so it was necessary to
adopt some simple means of measuring this factor even at the expense
of exactness. The various methods used for measuring light in terms
of chemical activity were considered as a possibility, but finally rejected.
The instrument finally adopted was based upon the principle of the
black body and measured the light in terms of heat units. It consisted

26 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

of two mercury thermometers mounted side by side in a white box.
The bulb of one was white and of the other, black. The readings
were recorded as the percentage of the maximum difference observed
during the season of 1920, this maximum being taken arbitrarily as
100 per cent.

Temperature measurements were made by means of mercury
thermometers. A white bulb mercury thermometer was used for meas-
uring air temperature in the sun. An interesting comparison of un-
covered mercury, white, black, and red spirit thermometers is shown
im Table I.

Table I. Comparative Readings of Thermometers with Differently Colored Bulbs
Taken at I p.m.

Light Light Light Light Light

Color of intensity intensity intensity intensity intensity
bulb 52% 20% 75% 72760 55%
Aug. 31 Sept. 1 Sept. 2 Sept. 6 Sept. 7
IIRC =5 shes cae, “RS E Ae AC. AlOy “1G, AG) AC 40) 3€
IRA SLGM A Seto sia soy AC 28.5316 B8:5.C Mi AG 20.5€
Mercury Sra... gis AE 26555 Cee ep AE ey GC, Says (C
WVilnite ey cecrec aahea(© Bie AS 27 mG aa EC 320, -€

Subcortical temperatures in the logs were measured by mercury
thermometers inserted in a hole bored into the end of the log just
beneath the bark.

The evaporating power of the air for each 24-hour period was
measured by means of Livingston porous cup atmometers. The white
spherical type was used. An average of readings from three cups
was taken for each set of logs. Since these instruments were left in
position during the entire season, it was necessary to equip them with
check valves to prevent the absorption of water during rains. A single
mercury valve mounting proved very satisfactory and caused little
trouble. A special mounting was designed for measuring the rate of
evaporation at any particular time. In this mounting the evaporation
during one minute was measured in a graduated capillary tube and
the rate per hour calculated.

Relative humidity was measured by the use of the cog psychrom-
eter (Clements 1905). This instrument has proved very satisfactory,
as it is accurate and easily operated in a limited space.

Measurements of the moisture content of the cambium and outer
sapwood regions were attempted by running moisture analyses of sam-

EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 27

ples taken from the logs. The method was too slow and cumbersome
to give satisfactory results.
Influence of the Character of Food

Food is one of the important factors limiting insect development
in logs. Some forms are very exacting in their food requirements
and their development is only possible within narrow limits. Others
are not so exacting and are therefore found under a wider range of
conditions. Insects working in freshly cut logs may be divided into
several ecological units on the basis of food.

1. Insects requiring fresh cambium. These forms are living in a
highly nutritious medium and are therefore not greatly dependent
upon the aid of microérganisms. Examples of this group are
many Ipidae.

. Insects requiring fresh cambium for early development and which
are later able to complete their growth and development in the
outer sap wood. Many Cerambycidae and Buprestidae come under
this head.

3. Insects requiring fresh cambium during their early stages, but
later capable of entering both sap wood and heart wood to com-
plete their development. Examples are Monochammus and Chal-
cophora.

4. Insects which live in the wood during the entire development period,

such as the Siricidae.

. Insects which do not depend directly upon the wood for food, but
live upon organisms growing in the wood. This group may be
exemplified by Gnathotricus.

The maximum length of the insect’s developmental period is limited
by the time that its food remains in a usable condition. Insects of the
. first group must complete their development while the cambium is still
fresh and green. Thus their developmental period must be short. The
second and third groups require green cambium for only a compara-
tively small portion of the entire developmental period, therefore their
cycle may be almost indefinitely lengthened.

i)

ol

Influnce of Light and Heat

Insects react in much the same way to both light and heat. Since
as a rule these factors are closely associated with one another and,
under outdoor conditions, usually vary synchronously, it is often im-
possible to determine whether the effects are produced by the one or by
the other. For this reason it seems logical that they should be considered
together.

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EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN: LOGS 29

Both these factors are exceedingly important in their influence.
upon insect activities. Insects vary both within the species and between
species as to their reactions to these factors, but in each case tempera-
ture and probably light also can be divided into optimum, effective,
high and low dormant, and high and low fatal zones. It seems prob-
able, however, that light under natural conditions seldom goes beyond
the limits of toleration for most insects. It does, however, have a
stimulating effect as shown by Hennings (1907) who noted that Ips
typographus Linn failed to develop normally in the absence of light,
and by the fact that Chrysobothris adults remain inactive on cloudy
days at temperatures equal to or higher than the temperature at which
they are active on sunny days.

The influence of heat and of light converted into heat may be
observed in all stages of insects -from egg to adult. Hennings (1908)
has shown the effect of different degrees of temperature and humidity
upon each step in the life history of [ps typographus Linn. Some of
his results are set forth in Table II.

In correlating the period of activity of Chrysobothris adults, our
experiments show that of the factors which influence the activity of
these insects, temperature ranks first and light next, while relative
humidity appears to have little influence. Under bright conditions
activity begins at 26°C. and full activity is reathed.:at 30°C. Under
cloudy conditions they remain inactive until 29°C. With these insects
there seems to be a marked daily periodicity which appears to be inde-
pendent of both light and temperature. Regardless of conditions they
are seldom active before 8:30 a.m. or after 4:30 p.m.

Some other Buprestids appear to have a somewhat lower active
temperature, since Chalcophora and Dicerca were observed flying when
conditions were not favorable for Chrysobothris. In contrast to the
narrow range of activity of Chrysobothris, Monochammus was observed
actively feeding and flying from early morning to sunset.
~ The rate of larval development of wood-boring insects varies
greatly, owing not only to quality of food, but also to temperature dif-
ference. Monochammus will frequently come to maturity in a single
season under favorable conditions, whereas under cool, shady conditions
three years or even longer are required to complete development.

Factors Influencing Subcortical Temperature
The recent work of Craighead (1920) calls attention of ento-
mologists to the high temperatures which occur under the bark of logs
lying in the sun. That this is not the first time this phenomenon has
been noted is evidenced by the repeated reference in bark-beetle

30 NINETEENTH REPORT STATE ENTOMOLOGIST OF MIN NESOTA—I922

literature to heat paralysis, or estivation. Craighead’s article emphasizes
the fact that solar radiation may raise the subcortical temperature above
a point fatal to the insect inhabitants of the logs. He observed sub-
cortical temperatures exceeding air temperature by 60°F. depending
upon locality, condition of sky, and angle of sun’s rays.

The present experiments have shown that the chief factors influ-
encing subcortical temperatures may be summarized as follows:

1. Solar radiation
a. Light intensity
b. Solar altitude
c. Angle of incidence
Character of bark
a. Color
b. Surface
CSS truchire
d. Thickness
Air temperature
Air movement
Evaporation from bark surface
6. Proximity to other radiating or absorbing surfaces.

The highest temperatures recorded were observed beneath the
dark colored bark of White pine. Frequently the noon temperature
exceeded a point fatal to insects and several times reached 60°C.
Under the bark of Norway pine, however, the temperature never was
observed to exceed 44°C., which is several degrees below the fatal
point of most subcortical insects. The fatal temperature for most
insects is about 48°C., altho there is evidence that some bark beetles die
at a somewhat lower temperature, whereas Chrysobothris is able to
endure slightly over 50°C. Tables III and IV show the effect of degree
of shade and the character of the bark upon subcortical temperature
for three species of pine during June, July, and August. From these
tables it is evident that the bark characteristics of the different species

to

ures

and the amount of shading the logs receiverhave a very decided influ-
ence upon the subcortical temperature.

As a result of these experiments it appears that 1n many instances,
even in northern latitudes, the weekly turning of logs as recommended
by Craighead would be effective in destroying wood-boring insects.
This is particularly true of logs with moderately thin dark colored
bark. It is equally evident that the method can not be applied to all
cases since some logs will remain below the fatal temperature of insects
even on very bright days.

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EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 33

Fatal Temperature of Insects in Logs

A consideration of temperatures fatal to insects in logs is essential
if we are fully to appreciate the significance of subcortical temperature.
The fatal temperature varies with the species and also with the indi-
viduals within the species. As a rule, however, a large proportion
(about eighty per cent) of the individuals of a species will succumb at
approximately the same temperature, and those dying above or below
this point must be regarded as erratic. The presence of about twenty
per cent of these erratic individuals makes it necessary to use a suffi-
ciently large number of specimens in each set of experiments to make
clear the distinction between normal and erratic.

In these experiments Pityokteines sparsus Lec. served as a repre-
sentative of the bark beetles and Chrysobothris dentipes as a representa-
tive of the Buprestids. It must not be assumed, however, that the other
species necessarily have the same fatal temperature as these, but it is
reasonable to assume from the results of these experiments that Pityok-
teines sparsus represents a group having a fairly low fatal temperature,
whereas Chrysobothris represents a group having a high fatal tem-
perature.

The experiments with Pityokteines sparsus were conducted without
removing the insects from the logs. The logs containing the insects
were exposed to full sunlight and the temperatures within the logs
were recorded every fifteen minutes. As the various degrees of tem-
perature were attained some of the pieces were removed to a cool
place and the condition of the insects was noted. These experiments
show that 43°C. marks the upper limit of activity, and 47°C. the fatal
temperature for this species. Between 43°C. and 47°C. the insects
are in a state of estivation. The fatal temperature for adult speci-
mens of Chrysobothris is about 52°C. No disturbance of the ability
of these insects to control their movements was noticed until a tem-
perature of 51°C. was attained. From this it appears that the zone
of estivation is very narrow with Chrysobothris. That larvae of
Chrysobothris are able to endure extremely high temperature is indi-
cated by their occurrence on the upper side of logs lying in full sunlight.

Cerambycid larvae are as a whole less able to endure high tem-
peratures than Chrysobothris. They are seldom found developing
normally on the upper side of logs exposed to full sunlight, but usually
confine their activities to the sides and bottom of such logs. Under
partial shade, however, they are active on the upper side.

34 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

The Influence of Moisture upon Insect Activity Within the Log

The effect of moisture upon insect activity has been shown to be
important. Shelford, Pierce, and others have shown that the optimum
temperature and the limits of effective temperature are greatly influ-
enced by humidity. By analogy it is reasonable to suppose that this
factor, the importance of which has been demonstrated for other in-
sects, is also of great importance to insects working in logs. The work
of Henning (1907) demonstrates that Ips typographus is influenced
in every stage of its development by this factor.

The influence of the relative humidity of the air is probably not of
such great importance to insects living within the log as 1s the moisture
content of the wood and inner bark. It does, however, have an influ-
ence upon rate of evaporation and therefore upon the rate of drying
of the log.

Distribution of Insects Under Different Conditions

An examination of the distribution of the different insects under
the four environmental conditions studied shows that these insects may
be grouped according to their ecological requirements. Under one set
of conditions certain species develop at the optimum rate. Under other
conditions development is slow, and under still others it is impossible.
Unfortunately the habits of different groups of insects are so variable
that it seems almost hopeless to find any method of handling and
storing logs that will prevent all insect infestation. Nevertheless when
we remember that not all insects working in a log are injurious, as
some do not enter the wood, we realize that our problem is not quite
so difficult as it first appears. When we can check the development
of the true wood-boring forms, our chief aim has been attained.

The study of the distribution of insects under different environ-
mental conditions illustrates how the species are grouped according to
their ecological requirements. The results may be outlined as follows:

Group 1. Insects requiring high temperatures for development—
represented by Chrysobothris.

Group II. Insects unable to endure extremes of temperature or
moisture—represented by bark beetles such as [ps pini. and by Mono-
chammus.

Group III. Insects requiring cool moist conditions—represented
by Hylurgops and some Cerambycidae.

The insects of Group I are found on the upper side of logs in
full sun, one-third shade, and to a lesser extent in one-half shade.
They are usually most abundant in full sun altho this varies with the

EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 35

character of the log. They occur rarely on the sides of logs and almost
never in heavy shade.

The insects of Group II are more generally distributed. In full
sun they occur most commonly on the side of the logs, whereas in three
quarters shade they find optimum conditions on the top surfaces. They
are not usually abundant on the lower surfaces.

The insects of Group III are confined for the most part to the
lower side of the logs where moist conditions maintain. Few of them
are injurious.

The results so far obtained seem to indicate that logs in heavy
shade are less subject to insect injury than logs in more exposed
situations. This appears to be due primarily to the reduced rate of
development under cool, shady conditions.

Effect of Relative Humidity and the Evaporating Power of the Air

When this problem was undertaken it was thought probable that
relative humidity and the evaporating power of the air would be found
to have a marked effect upon the activity of insects in logs. For this _
reason careful observations of these factors were made using the
instruments already described, 1.e., the Livingston porous cup atmom-
eter and the cog psychrometer. The daily records of these factors
were plotted in graphic form on profile paper together with the daily
records of light, air temperatures, and subcortical temperature of typical
logs. The graphs, however, failed to prove any definite effect of
either the evaporating power of the air or relative humidity. Altho
from this experiment no conclusions can be drawn as to the effect of
relative humidity and evaporating power of the air, it still appears
possible that both these factors have a decided influence upon the

activity of xylophagous insects.

Conclusions

These experiments have shown that the activities of insects work-
ing in logs are greatly influenced by the environmental conditions to
which they are exposed. These conditions are in many cases controlled
or modified by the action of external physical factors such as light,
heat, and moisture. The effect of these factors upon the conditions
within the log to which the insects are exposed varies according to
the characteristics of the species and the characteristics of the indi-
vidual log within the species. i

The food value of logs is determined primarily by the chemical
composition, which is in turn dependent upon the species of tree and
the part of the log under consideration. The cambium and phloem

36 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—1IQ22

regions are comparatively high in protein, whereas the other parts
of the tree contain little protein, but are high in carbohydrates. The
differences in food value of the different parts of a log result in the
definite localization of certain insects within the log. These differences
also lead to variation in the rate of insect development, depending
upon nutritional conditions. Thus we find the rapidly developing insects
localized in the areas in which the wood is most nourishing, 1.e., the
cambium and phloem. The insects in the heart wood develop, as <
rule, quite slowly. In some cases development is made possible or
the rate of development is hastened by the presence of microorganisms
in the wood. These organisms, having the ability to convert cellulose
into proteins, sugars, and starches, increase the nutritive value of the
wood. It has been shown that many insects are unable to develop in
the absence of these organisms. In logs, the process of decay depends
largely upon the the character of infection and the time at which the
organisms gain entrance into the log. Insect infection often determines
to a very marked degree the time and the extent of fungous infection
in the log.

One of the factors which is obviously of the greatest importance
in regulating insect activity within the log, is heat. Since a large pro-
portion of the light which strikes upon the log is converted into heat
units, it is very difficult, in the effect upon insects, to distinguish be-
tween these two factors. Heat may be divided into optimum, active,
dormant, and fatal zones, and theoretically light may also be thus
divided. The effect of temperature has been shown to vary according
to humidity conditions. There is evidence that variations of light
intensity also influence the effect of temperature upon insects. It
has been shown by experiments and observations with Chrysobothris
adults that changes of temperature may bring about changes in the
reaction of insects to light. Differences in temperature conditions as
they occur in nature are sufficient to account for the great differences
in the length of life cycles of insects which have been observed. This
is well illustrated in Monochammus which may, under favorable con-
ditions, complete its development in a single season, whereas under
less favorable conditions two or even three years are required.

The correlation of temperature, light, and relative humidity read-
ings with the active periods of the insects living under natural con-
ditions has shotvn that conditions favorable for the activity of one
group are not necessarily favorable for the activity of another group.
Monochammus adults appear to have an extremely wide range of
active temperature, and for this reason fly at almost any time during

EFFECT CF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 37

the day. Chrysobothris, however, requires high temperature and bright
sunlight before it reaches its maximum state of activity. Other bupres-
tids, such as Dicera and Chalcophora, are active at lower temperatures
than Chrysobothris.

Subcortical temperature was found to be very variable in the same
log. Also there was considerable difference between logs of the same
species and still more between logs of different species. The subcortical
temperature on the upper side of certain logs exposed to full sunlight
often reached a temperature far above that fatal to insects. Craighead
also found this to be true, and recommended that advantage be taken
of solar radiation in the control of wood-boring insects. The present
series of experiments has shown, however, that the application of this
method is limited in its scope, and can not be applied to all logs under
all conditions. Many heat resistant insects, such as Chrysobothris larvae,
are able to withstand extremely high temperatures for short periods
of time, and are thus able to survive and develop normally on the
upper side of many logs lying in the sun. It is true that most insects
succumb to such conditions. On the other hand, some logs, such as
those of Norway pine, which have scaly bark, highly efficient as an
insulator, never reach extremely high temperatures.

Solar radiation, the character of the bark, air temperature, air
movement, evaporation from the bark surfaces, and proximity to other
radiating or absorbing surfaces, are the most important factors control-
ling the subcortical temperature of logs.

The fatal temperature of insects, like their effective temperature,
varies under different conditions. There is considerable variation
within a single species and even greater differences between different
species. From the series of experiments described in this paper it

appears that Chrysobothris has a much higher fatal temperature than“

any other of the insects studied. The adults were able to endure tem-
peratures up to 52°C., while the larvae apparently were still more re-
sistant to heat. Cerambycid larvae have a much lower fatal tempera-
ture than Chrysobothris. The only bark beetle for which the fatal
temperature was determined was Pityokteines sparsus Lec. It was
shown to be comparatively low for this species of beetle, as they passed
into, a state of estivation at about 43°C. and were practically all killed
by a temperature of 47°C. This is about the point at which the majority
of insects succumb.

That moisture conditions within the log have an important effect
upon the activities of xylophagous insects can not be doubted. This
is shown by the distribution of beetles in logs under different conditions.

38 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—19Q22

It was found that some insects are very exacting in their requirements
and occur only in narrowly limited areas. For example, Hylurgops
pinifex is always found in cool moist locations. Unfortunately, the
attempt to measure the moisture content of logs was not attended with
much success because of the few observations which could be made
during the season. For this reason a direct experimental correlation
of this factor with insect activity was impossible.

The effect of the physical factors of the environment upon insects
in logs is well illustrated by the distribution of these insects under
different conditions. The effect of high temperature is clearly shown
in logs in the open. On the upper side of these logs are found only
insects which are most resistant to heat, such as Chrysobothris. In
the cooler portions, however, other species make their appearance.
Under the shade where cooler conditions obtain, the heat loving insects
disappear, whereas the insects which develop best under cool condi-
tions become more and more abundant with increasing shade. Three
quarters shade was the heaviest used in these experiments. Under
this condition no Chrysobothris was present and there appeared to
be some indications of a reduction in abundance of Monochammus.
Under these conditions there was a distinct reduction in the develop-
menial rate of all species represented. From this it seems probable
that still greater shading would check Monochammus as well as Chrys-
obothris. If this is true, the shading of logs which must be left in
the woods over the summer season by covering them with brush or in
some other way, may prove the most satisfactory method for control-
ling wood-boring insects.

From this series of experiments no attempt has been made to
formulate definite recommendations for controlling wood-boring insects.
Rather than to present a solution of an immediate problem the aim
of this work is to lay a foundation for further investigations of a
more .immediate practical nature. These experiments, however, have
shown conclusively that the activities of wood-boring insects are con-
trolled very decidedly by the action of external factors, and that the
zone of their optimum development is often very narrow. These
results indicate that further investigations may make possible the
formulation of simple, inexpensive, and practical control measures. It
will, in all probability, be possible to control wood borers by very
slightly modifying the present-day methods of handling logs. If this
work can form the basis for further development in the control of
injurious wood borers, it will have justified the expenditure of all the
time and energy required in its prosecution.

EFFECT OF PHYSICAL FACTORS IN ECOLOGY OF INSECTS IN LOGS 39

BIBLIO GIRAREDY

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40 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

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, 1898. Life zones and crop zones of the United States. Bulletin
10, Biological Survey, U. S. Dept. of Agr.

Niisslin, O., 1904. Die Generationsfrage beiden Borkenkafer. Nat. Zeitschrift fur
Land-u. Forstwirtsch. 3. 1904.

Peairs, L. M., 1915. The relation of tempereture to insect development. Jour.
Econ. Ent. 7: 174-183.

Pierce, W. D., 1916. A new interpretation of the relationships of temperature
and humidity to insect development. Jour. Agr. Res. Vol. 5, No.°25, pp.
1183-1101.

Sanderson, E. Dwight, 1908. The influence of minimum temperature in limiting
the northern distribution of insects. Jour. Econ. Ent. r: 245-262.

, I9t0. The relation of temperature to the growth of insects.

Jour. Econ. Ent. Vol. 3, No. 2, pp. 113-140.

2 , and Peairs, L. M., 1913. The relation of temperature to insect
life. N.H. College of Agr. Exp. Sta. Tech. Bul. 7, Dec. 1913.

Shelford, V. E., 1913. The reaction of certain animals to gradients of the evapo-

' rating power of air. A study in experimental ecology. Biol. Bul. XXV:
79-120.

Swaine, J. M., 1908. Canadian berkbeetles, Part I]. Bul. 14, Part II, Ent. Branch

Dept. of Agr., Ottawa.

DERRHS AS Ay PARASIEICIDE*

By Paut M. GILMER

Derris, as at present produced commercially, is the product ob-
tained by grinding the dried roots of certain tropical plants belonging
to the genus Deguelia. It has long been known that in the tropics
the macerated roots of these plants are used by the natives for stupify-
ing fish, a fact which has recently led to investigations as to its possible
value as an insecticide. .

In 1919, McIndoo, Sievers, and Abbot called the attention of ento-
mologists to the insecticidal properties of derris. Independently, work
was also done by E. Mathieu, 1920, in the Straits Settlements, and: by
C. J. J. Van Hall, 1920, in the Netherlands’ East Indies, upon its

___ properties as a controller of certain insect pests. All found it to possess
marked insecticidal properties.

In view of the desirability of developing satisfactory powders for
the control of external parasites on animals, and because of the paucity
of data concerning the properties of derris, it seemed desirable to
extend these experiments with the following questions especially in
mind :

1. Is derris a practical and economical insecticide ?

2. Is it advantageous to mix the powder with tobacco dust, and
if so in what proportions is it most effective?

3. What, if any, is the effect upon experimental animals?

4. What is the most practical method of applying it ?

5. Against what type of insects is it most effective?

6. Are the powder and liquid extract equally effective and desirable?

The actual material used in the following experiments is made
from a South American species of Deguelia by an English corporation,
It is prepared both as a powder and as a liquid extract. The powder
is produced by grinding the dried roots, while the liquid derris is
the result of the extraction by certain liquid solvents of the fibrous
residue from the ground roots used in the production of the powder.
It was furnished by the American Tobacco By-Products and Chemical
Corporation, of Louisville, Ky., which at present holds a monopoly of
the supply of the manufactured material for this country.

The active principle is a resinous material, with a rather high
toxic property so far as the higher invertebrates are concerned. It

* Published with the approval of the Director as Paper No. 396 of the Journal Series
of the Minnesota Agricultural Experiment Station.

42 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

seems to act both as a stomach poison and as a contact insecticide.
Results obtained in the following experiments seem to indicate that
it also possesses considerable toxicity for vertebrates.

The liquid derris used was said to contain 16 per cent active derris
and 84 per cent inert substances, the latter being for the grea‘er part
apparently pyridine, which is probably used as the solvent for the
derris resin.

No analyses were made of the composition of the powder, largely
because of the technical difficulties involved and because it would
unquestionably vary considerably in different samples, owing to the
manner of its manufacture. It is suspected, however, that it contains
on the average between Io and 20 per cent of the active resin, the
residue being cellulose, the debris of ground roots, etc. The powders
were used as furnished by the By-products corporation and had the
following compositions :

Powder No. 1. Derris powder 10 %—Tobacco dust co %
No. 2. Derris powder 734%—Tobacco dust 921%4%
No. 3. Derris powder 100 %—Tobacco dust 00 %
No. 4. Derris powder 20 %—Tobacco dust 80 %
No. 5. Derris powder 714%—Tobacco dust 671%44%

Powdered sulphur 25%

The experiments were of two general types; those performed with
the derris powder as furnished, and those with the liquid derris extract.
The experimental animals were cats, dogs, white rats, and chickens;
the insects being fleas, lice, chicken lice, and to some extent cockroaches.
The fleas included the rat flea Ceratophyllus fasciatus Bosc., and the
cat and dog fleas, Ctenophalus canis Curt. and C. felis Rothsc.. The
chicken lice included both the body louse, Menopon biscriatum Paiget,
and the head louse, Lipeurus heterographus Nitzsch., but especially the
latter. The rat louse was the common louse of these animals, Polyplax
spinulosus Burm. The cockroaches included the American roach,
Periplaneta americana Linn., and the croton bug, Blatta gerimanica
Linn.

The experiments began with the use of white rats which were
infested with the rat louse. It was found at once that a very slight
amount of the powder was effective against the insects. It was ordi-
narily applied by small pinches rubbed into the fur, usually two on the
back, one on the belly, and two small pinches on the flanks—five in all.

When used pure the powder (No. 3) acted with surprising rapidity,
the animal usually being practically free of lice within a few hours
(usually from three to five hours). In every case, however, where
the pure powder was used the rats were sick on the following day; a

DERRIS AS A PARACITICIDE 43

profuse, watery diarrhea was noted, the nose was dry, respiration rapid,
and the animal gave every symptom of high fever. Thirst seemed
insatiable, the animal lying by the water container and drinking repeat-
edly. In all cases but one, death ensued within three or four days,
the body being exceedingly emaciated. The surviving case had been
given a rather smaller dosage (three pinches only, one applied to the
belly and two to the back). This animal recovered from the effects
of the derris but never again became vigorous. It died about a month
later from a pulmonary infection with which it had previously suffered.
There can be little doubt that the severe illness due to derris poisoning
considerably hastened its death. The powder acts as an internal poison,
being licked off the fur by the animals in grooming their coats.

The pure powder was used-rather sparingly on a full grown cat
for the flea, C. felis. The animal was completely rid of the insects,
and seemed to suffer but slight inconvenience. There was no sign of
the diarrhea so pronounced in the rats, but some symptoms of a feverish
condition in its dry nose and a desire to drink. The cat was fully
recovered in forty-eight hours and suffered no further inconvenience.
The amount of powder used per unit of body weight was considerably
less than with the rats, approximately one fourth to one third, it is
estimated. No attempt was made to weigh the powder, as the inevit-
able wastage in applying it made such a procedure seem a useless check.

With a small puppy, about the same size as the cat used, so far as
could be noted, the powder produced no ill effects, and was certainly
effectual in removing the fleas, C. canis, with which the animal was
heavily infested. On both the cat and the dog, the powder was applied
in generous pinches on the back, belly, and flanks, and rubbed in by
stroking the animal against the “lay” of the fur. On both the cat and
the dog the insects were quickly stunned, dropping to the paper upon
which the animal was placed and, so far as noted, never recovered
more than enough to crawl weakly for a short time.

Following this series of tests with the pure derris powder, similar
experiments were made with the various diluted powders. Ail were
found more or less effective, but there was considerable variation in
their efficiency and time of reaction. Rats were again largely used as
experimental animals, both because they were easier to handle and to
keep, and because they were more easily reinfected after having once
been cleared of parasites. The insects tested against were again the
rat louse and the rat flea. The general results are discussed in the
following paragraphs.

44 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

A rat, heavily infested with lice, was isolated and dusted as
previously mentioned with five pinches of powder No. 2 (derris 712%
—tobacco dust 92'4%4%). Twenty-four hours later there were still
a considerable number of live lice present, altho the number was very
considerably reduced. Forty-eight hours after treatment the number
was still further reduced. A second and a third dusting produced like
results, the third practically removing all lice.

A rat with a light flea infestation and a fairly heavy louse
infestation was: isolated and treated with powder No. 2 as above. Re-
sults were very similar to those obtained in the former experiment.
No fleas were observed after the second application. It was noted,
however, that the fleas that dropped from this rat very shortly after
dusting seemed only stunned. Many of them recovered and were
used to infect clean rats. It appears that the fleas endeavor to leave
the treated rat to a certain extent. This may account for the faet
that the dusting is not quite so effective in killing them as in killing
the lice, and for the further fact that the second treatment completely
cleared the treated rat. No attempt was made to trap the fleas.

These two experiments are fair samples of all those made with
powder of this strength. The powder is moderately effective in this
dilution but not so much so as are the slightly higher concentrations.

Powder No. 5 is similar to No. 2 in derris content but contains
62%% tobacco dust and in addition contains 25% sulfur in a very fine
state. The results of the trial were slightly more satisfactory than with
the No. 2 powder, owing doubtless to the action of the sulfur. The
following typical experiments show the usual results.

A rat, infested with lice, was powdered as usual with five pinches
of No. 5 powder. Twenty-four hours later the number of lice was
very much reduced, the infestation remaining practically constant again
after forty-eight hours. Twenty-four hours after the second treat-
ment no lice were noted after a careful search. This rat was kept
isolated and in a few weeks again developed lousiness, probably from
the hatching of the numerous eggs contained in the fur.

A second rat, lousy, and with a slight flea infestation, was treated
as usual. Most of the fleas left the animal at once, dropping on the
paper a few minutes after the powder was applied. These fleas seemed
badly affected by the powder, but a fair percentage (approximately
one fourth) recovered after a few hours. This rat was given no second
treatment, as the first completely removed the fleas by either killing
the insects or causing their migration. It was noticed, however, that

DERRIS AS A PARACITICIDE 45

the louse infestation was again very much reduced. There is no doubt
that the No. 5 mixture is considerably more efficient than the No. 2
containing the same percentage of derris.

A rat heavily infested with lice was treated with the No. 1
powder (containing 10% derris and go% tobacco dust). The effec-
tiveness of this powder was about equal to that of No. 5 so far as lice
were concerned, possibly a little more efficient, but two treatments
were necessary to clear the infested animal. Upon continued isolation
infection again appeared in about the same time (two to three weeks)
as in the animals treated with the No. 2 powder, due again probably
to the hatching of the eggs in the fur.

A rat lightly infested with fleas was treated. This treatment
was apparently more efficacious than the No. 5 treatment, the fleas
leaving the animal but very few surviving after doing so. One treat-
ment completely cleared the animal of fleas, and it is calculated that
about 90% of those found on the paper did not survive. No count
was made, the paper containing the fleas being placed over a rat cage
in order to save the live fleas for further use.

The best results were obtained with powder No. 4. This powder
contains 20% derris and 80% tobacco dust. A lousy rat treated with
this powder showed no appreciable number of live lice after twenty-
four hours. A second, examined after twenty-four hours, showed
a few exceedingly sluggish lice. An isolated animal did not show
‘reinfestation within two weeks and a half, when it was returned to
the general hutch for reinfestation. This animal, the same that had
been treated about a month previously with No. 2 powder, did not
carry a large number of eggs, altho a few were noticeable on the
fur at the time of treatment with the No. 4 powder.

A flea-infested rat was treated, and again the rat was flea-free with-
in twenty-four hours. Apparently none of the fleas that dropped off
this rat within the first five minutes recovered. Upon making a second
test on another rat, of the seventeen fleas dropped off in the first
five minutes none had recovered twenty-four hours later. These fleas
were placed under a bell jar after being counted. This rat was given
a rather heavy treatment, the pinches being generous, and since the
animal was a large one, seven pinches were applied. It was acci-
dentally returned ‘to the flea-infested hutch immediately after treat-
ment. This hutch had a moderate infestation with fleas, and a grow-
ing crop of larvae. Three days later a rat was removed for examination
and no fleas were found. Altho it is not certain, it is probable from
the results of later experiments that the powder retained in this rat’s

46 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

fur was distributed to the other three rats in the hutch as they lay
sleeping together, and was finally scattered over the floor litter. [:x-
amination of the litter showed a remarkable reduction in the number
of live larvae present. This same accident happened twice during the
experiments, the second one completely destroying the flea infestation,

As a new flea culture was not obtainable, the experiments with
fleas on rats were discontinued. However, some further work was
done on stray cats and one experiment was made on a dog, all of which
showed the 20% derris—80% tobacco dust mixture was very effective
against fleas on these animals. The dog was treated by heavily dusting
the rags in the box in which it slept. The method seemed completely
effective against the fleas and also killed the few larvae contained in
the old cloths. The work on cats was less satisfactory, as it was diffi-
cult to apply the powder effectively to them since they were all rather
wild and objected strenuously to being handled.

Of the series of powders used, the No. 4 powder (derris 20%=—
tobacco dust 80%) seemed to be the best combination. When used
on rats pure derris proved fatal to the experimental animal in all but
one case, in which it was used very lightly. While all the powders
produced slight symptoms of illness in rats, none except the pure derris
produced any permanent ill effects. The 20% derris completely re-
moved both the louse and flea infestations in one treatment, and the
fleas did not revive after dropping off the animal. From the results
obtained by placing the treated rats immediately in the flea-infested
cages it seemed evident that direct treatment of the infested animals
was not absolutely necessary. A series of tests was made,. therefore,
to determine if treatment of the nests or bedding was a practical method
of eliminating the insects.

Three rats heavily infested with lice were put in a clean cage
with chip litter. Excelsior was used for nesting material and a small
teaspoonful of derris powder No. 4 was shaken loosely into the excelsior.
The rats quickly worked this over into a nest, spending most of their
time beneath it. Examination two days later showed no appreciable
infestation with lice. The rats were left in the cage about a month
and showed no reinfestation until again placed with infested rats for
reinfestation. The experiment was repeated several times with from
one to three rats with essentially similar results.

A similar experiment was tried with a small kitten harboring the
cat flea, C. felis. Derris powder No. 4 was scattered over the old coat
used as a bed for the kitten. This coat had a fair number of flea

DERRIS AS A PARACITICIDE 47

larvae in it, and the kitten showed a moderate infestation. Three days
later no live larvae were found, altho the kitten still harbored some
fleas. The kitten was not completely cleared, altho the number of
fleas was very considerably reduced. She had the run of a small
room with dusty earth as a part of its floor. She was accustomed to
lie in this dust a considerable part of the time, and this probably served
as a flea breeding ground which was untouched by the powder. It
seems reasonable to believe from the gradual reduction in the number
of fleas found upon her, together with the non-appearance of live
larvae in the bedding box, that under the usual conditions, where the
cat has free run and sleeps largely in the usual bedding box, this
method will effectually clear the animal of fleas.

Since this same method had already been shown to be successful
in the puppy experiment, no further work was done with dogs.

This latter phase of the work was not undertaken until late in the
summer and during the winter, and the possibility of its application
to sitting hens was not worked out. There is, however, more than an
even probability that it may be of value in the treatment of nesting
material for sitting hens for the purpose of destroying lice and mites.
There are no data on its effect upon the viability of incubating eggs,
but since the effective agent is a non-volatile resin, and tobacco dust
is known to be non-injurious, there is no reason to anticipate any ill
effects from its use. The fact, furthermore, that it retains its efficiency
upon exposure to air without deterioration would add very consider-
ably to its value for this purpose. It is intended to carry out investi-
gations upon this phase of its use.

The work which was done in testing the efficiency of the powder
as a louse remover with chickens showed it to be effective, but no
more so than the familiar sodium fluoride. Its action is slower but
equally certain. In the dry form it has certain advantages. It is not
so irritating to the eyes, nose, and lungs of either the operator or the
fowl as is the dry fluoride. It has no advantage over the fluoride dip
treatment, is not so rapid in its action, requires more time to apply,
and in all probability will never be as inexpensive as the fluoride treat-
ment. There is no doubt, however, of its efficiency so far as louse
removal is concerned.

A series of experiments with cockroaches was also undertaken.
Here the 20% derris-80% tobacco dust mixture was also found to be
effective, altho somewhat slow in action. Roaches forced to run through
the powder and then confined in cages or small glass jars all died
within twenty-four hours. These roaches were forced to run over a

48 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

considerable depth of the powder and were thoroly coated with it.
The powder was also mixed with flour and a little sugar and roaches
were allowed to feed upon it. It proved an effective stomach poison,
killing all the roaches experimented upon.

It was found fairly effective under the average conditions in which
such an insecticide would be used. The rat cages and the cracks in
the rough board tables were fairly heavily infested with cockroaches
(B. germanica) which fed upon the grain, etc., found in the litter of
the cages and upon the tables about them. The usual harbor was
beneath the cages. Derris powder No. 4 was scattered fairly thickly
about the cages and dusted into the cracks of the rough pine tables.
There was a very considerable reduction in the number of roaches
and with continued treatment they practically disappeared for some
weeks after the treatment was discontinued.

In comparison with sodium fluoride for this purpose, derris has
no advantage except that it is considerably less irritating to the mucous
membrane of the nose, eyes, and respiratory passages; being, in fact,
practically nonirritant unless inhaled in considerable quantities, when the
tobacco dust will cause sneezing and coughing.

It is believed that derris is not quite so efficient as fluoride, and
undoubtedly is much slower in action, as well as more expensive.
Compared with a goodly number of the patented roach powders, how-
ever, it. is both much more efficient and much less expensive, besides
having the added feature of being non-deteriorating, a glaring fault
of most roach powders having pyrethrum as the insecticidal base.
Derris should be ranked second to sodium floride as a roach exterminator.

Some work was done with liquid derris. Its use upon animals
is not to be recommended. The odor is very strong and repugnant to
both animals and man, while the liquid is almost non-miscible and must
be used with some sort of emulsifying agent such as soap, which
makes it unhandy to prepare and use. As a spray for fruits and vege-
tables it seems to have no properties to recommend it above the ordinary
insecticides. Its efficiency is a little below the better nicotine prep-
arations, while its cost is no less and its preparation is more difficult
It does not mix well with sprays containing lime. It is, however, fairly
effective and sticks well. Its effect if eaten with cabbage, lettuce, etc.,
is not known. It is very slightly toxic, altho probably not to a sufficient
extent to cause illness in human beings in the quantities likely to be
consumed.

DERRIS AS A PARACITICIDE 49

Conclusions

From the experiments undertaken it is evident that derris furnishes
a very efficient insecticide, particularly when used as a powder against
ecto-parasites. It is effective, easily applied, not repugnant to the
animal or man, and retains its insecticidal properties unaltered in ihe
open air. It should be used about the same as pyrethrum powder, and
in the 20% derris-80% tobacco dust mixture affords a killing powder
about as great as commercial pyrethrum. Its stability in insecticidal
power recommends it above pyrethrum even at a slightly higher price.
It seems, however, to lack the instantaneous effect of the latter, and is
not effective against flies when blown into the air. As a check against
roaches, ants, and insect ecto-parasites, it is fully the equal of pyrethrum
as ordinarily purchased.

The powder is not now obtainable commercially. When finally
placed on the market it will probably cost about the same as pyrethrum,
possibly a little less, and should make a very desirable addition to the
means of combating household insects and external animal parasites.

Bibliography
McIndoo, Sievers, and Abbot, 1919—Derris as an Insecticide. Jour. Agric. Re-
search. Wash., D.C.; 17; No. 5, pp. 177-200.
Mathieu, E., 1920—Tuba Root (Derris eliptica) as an Insecticide. The Gardens
Bull. Straits Settlement, Singapore; 2; No. 6, pp. 192-197.
Van Hall, C. J. J., 1920—Derris als Insecticide. Teysmannia, Batavia; 31; No. 4,
pp. 159-166.

STUDIES: ON THE LIFE) HISTORY AND | BIOLOGY ee
PERILLUS BIOCULATUS FABRICIUS, INCLUDING
OBSERVATIONS ON THE NATURE. OF
Tae COLOR EAE a RIN:

(Heteroptera, Pentatomidae )

By Harry H. Knight

The writer’s attention was first directed to Perillus bioculatus when
specimens were found feeding upon the Colorado potato beetle, dur-
ing July, 1913, in Genesee county, N. Y. Upon finding a red and
black bug mating with a white and black individual, the idea imme-
diately occurred that here was a fine opportunity to study color inheri-
tance in an insect. Studies on the life history were at once begun,
and the writer has given more or less time each year since to the
rearing of this Pentatomid, except for the years 1917 and 1918.
After the close of the war, and with the writer’s removal to Minnesota
in 1919, the study of Perillus was begun anew when the species was
found fairly abundant in the vicinity of St.. Paul. The first three
years, or from 1913 to 1915 inclusive, were given over to breeding
experiments and the study of color inheritance in the bugs. By the
close of 1915 it became quite evident that the color forms could not
be segregated by ordinary methods of breeding, but that individual
colors were more dependent on the external conditions under which
the bugs were reared. The season of 1916 was given over to a study
of the factors influencing the color pattern of the bugs. The work
on Perillus at Minnesota during the last three years has been chiefly
on the nature of color, as well as a continuation of study on the factors
influencing the color in individual bugs.

Since the double-eyed soldier-bug is of economic importance in
the control of the Colorado potato beetle, the present paper is given
over largely to an account of the life history and biology of the species
with data on its importance as a beneficial insect. ;

1 Published, with the approval of the Director, as paper No. 303 of the Journal Series
of the Minnesota Agricultural Experiment Station.

Or
a)

STUDIES ON PERILLUS BIOCULATUS FAB.

The following topics are discussed :
Classification and synonomy of Perillus biocu'atus
History and distribution
Methods of rearing

Life history

Life cycle

Egg cluster

Oviposition

Fecundity of females

Incubation

Hatching

Nymphal instars

Feeding habits of nymphs

Habits of edults

Mating habits

Length of life

Hibernation :

Determining the fatal minimum temperature by the thermoelectric method
Economic importance of Perillus
Kinds of insects fed upon by Perillus
Technical descriptions
The egg
Nymphal instars
The adult
Color varieties
_ Nature of the color pattern
Chenge of color in adult
Relation of temperature to color forms
Relation of color to sex
Conclusion
Perillus circumcinctus Stal
Notes on the life history of Perillus circumcinctus

Literature cited

Classification and Synonomy

The double-eyed soldier-bug was first described by Fabricius (1775)
as Cimex bioculatus, from specimens which had been collected in
America by Drury. The same author in his later works (1781, 1787,
1794, and 1803) records the species by repeating the original descrip-
tion but without adding additional information. Goeze (1778) and
Gmelin (1788), both record Cimex bioculatus, but merely transcribe
the original description by Fabricius.

Thomas Say (1825) described this species as new, under the name
Pentatoma clanda, and recorded it as inhabiting “Missouri.” Say states
that the species is very variable and describes varieties a, b, and c. Stal
(1872) placed bioculatus in his genus Perillus, which in 1862 he had

on
i)

NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I19Q22

described as a subgenus of Oplomus for the reception of confluens
H. S., and his new species virgatus and circumcinctus. In the opinion
of the present writer, virgatus Stal is nothing more than one of the
many color forms exhibited by Perillus bioculatus. Distant (1880),
under the name virgatius Stal, gives a good figure of a pale color phase
of bioculatus. In a majority of specimens of this white color form,
the black bar on the anterior portion of the pronotum is separated
by a white median line, but not always, for the writer has a few
specimens in which the black is united to form a transverse bar, as
shown by Distant.

Uhler (1872), under the name Perillus claudus, records bioculatus
from the western territories of the United States, and in subsequent
papers records the species from various western localities. Under
the name Perillus splendidus, Osborn (1894) recorded from Colorado
what was undoubtedly a dark red form of bioculatus.

Schoutedon (1907) made bioculatus Fabricius the type of a new
genus, Perilloides, but later workers have rejected this name, believ-
ing that confluens H. S., genotype of Perillus, is really congeneric with
bioculatus Fabricius.

The present synonomy of the species is as follows:

1775 Cimex biocu’alus Fabricius, Syst. Ent., p. 715.

1778 Cimex bioculatus Goeze, Ent. Beytr., ii, p. 248.

1781 Cimex bioculatus Fabricius, Spec. Ins., ii, p. 358.

1787 Cimex bioculatus Fabricius, Mantissa Ins., ii, p. 295.

1788 Cimex bioculatus Gmelin, in Linnaeus, Syst. Nat., Edn. 13, i, pt. 4, p. 2157.
1794 Cimex bioculatus Fabricius, Ent. Syst., iv, p. 120.

1803 Cimex bioculatus Fabricius, Syst. Rhyng., p. 175.

1825 Pentatoma clanda Say, J1. Acad. Nat. Sci. Phil., iy, p. 312.

1859 Pentatoma clanda Say, Compl. Writ., ii, p. 240.

1862 Oplomus (Perillus) virgatus Stal, Stett. Ent. Zeit., xxiii, p. 80.

1870 Perillus virgatus Stal, Enum. Hem., i, p. 32.

1872 Perillus bioculatus Stel, Enum. Hem., ii, p. 120.

1872 Perillus claudus Uhler, Hayden’s Surv. Terr., Rept. for 1871, p. 395.
1875 Perillus claudus Uhler, U. S. Geog. Surv. w. 100th mer., V, chap. xii, p. 830.
1876 Perillus claudus Uhler, Bul.. U. S. Geol. Geog. SUG. 1 ao. Some

1877 Perillus claudus Uhler, Bul. U. S. Geol. Geog. Sury., iii, p. 308.

1877 Perillus claudus Uhler, Wheeler’s Rept. Chief. Eng., for 1877, p. 1323:
1878 Perillus claudus Uhler, Bul. U. S. Geol. Geog. Surv., iv, p. 504.

1880 Perillus virgatus Distant, Biol. Cen.-Amer., Rhyn., i, p. 34, pl..3, hisses
1886 Perillus claudus Uhler, Check List Hemip., p. 4.

1893 Perillus bioculatus Lethierry and Severin, Cat. Genl. Hemip., i, p. 206.
1894 Perillus claudus Uhler, Proc. Calif. Acad. Sci., ser. 2, iv, p. 228.

1895 Mineus bioculatus Gillette and Baker, Hemip. Golo! ip 12:

1895 Perillus claudus Gillette and Baker, Hemip. Colo., p. 12.

1904 Perillus bioculatus Van Duzee, Trans. Am. Ent. Soc., xxx, p. 66.

STUDIES ON PERILLUS BIOCULATUS FAB.

or
ir

1907 Perilloides bioculatus Schoutedon, Genera Ins., Fasc. 52, p. 37.

1909 Perilloides bioculatus Kirkaldy, Cat. Hemip. Heterop., i, p. 6.

1910 Perillus bioculatus Banks, Cat. Hemip., p. 95.

1912 Perilloides bioculatus Zimmer, Univ. Nebr. Studies, x1, p. 234.

1917 Perillus bioculatus Van Duzee, Cat. Hemip., p. 73.

1917 Perillus bioculatus var. clanda Van Duzee, Cat. Hemip., p. 74.

1919 Perillus bioculatus Hart, Bul. Il. Nat. Hist. Surv., viti, p. 198.

1920 Perillus bioculatus Stoner, Univ. lowa Stud. Nat. Hist., vii, No. 4, p. 117.

History and Distribution

The original home of Perillus bioculatus appears to have been the
eastern slopes of the Rocky Mountain region. From there it has
migrated eastward, apparently following the movement of the Colorado
potato beetle, which forms its natural food. Thomas Say (1825) des-
cribed this species from material collected during the expedition of
Major Long to the Rocky Mountains, and altho the author states
that the species “inhabits Missouri,” the specimens described were
probably collected in the western part of that territory.

What appears to be the first published account of Perillus bioculatus
as a beneficial insect feeding on the Colorado potato beetle, is given
in a bulletin by Howard (1900). This record is in the form of a
letter, which was accompanied by specimens, from Mr. J. A. Green,
Waynoka, Oklahoma. The letter, dated September 16, 1899, describes
the feeding habits of Perillus on the Colorado potato beetle, with notes
on the life history and relative abundance of the species.

An unpublished account of observations on Perillus bioculatus was
recently related to the writer by Dr. H. B. Hungerford. He states
that as a small boy, during the summer of 1896, when living near
Fairbury, Neb., it was his task to rid the potato vines of the Colorado
potato beetle. Then it was that he became acquainted with a con-
spicuous stink-bug, black in color and varied with white, yellow, or
red, which was present in some numbers feeding on the potato beetle.
The predaceous habits of these bugs proved of such interest that speci-
mens were placed in cages where he fed them daily with grubs and
adults of the potato beetle.

The eastward movement of Perillus bioculatus is reflected to a
certain extent in the writings of various entomologists who have
noticed the predaceous habits of the bug in its relation to the Colorado
potato beetle.

Osborn (1892) listed Perillus bioculatus from Iowa, and indicated
that it occurred rarely in the state. Stoner (1920), in a comprehen-
sive account of the Scutelleroidea of Iowa, records only three speci-

54 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—1I922

mens from the state. This would indicate that the species is still rather
scarce, or perhaps the collectors have neglected to look in potato fields.

In his annotated list of the Pentatomidae, Van Duzee (1904) re-
corded Perillus. bioculatus from New Mexico, Colorado, Kansas, Ne-
vada, Idaho, and Montana.

Pettit (1908) reported Perillus bioculatus from Michigan and gave
the following note: A predaceous bug “appeared during the summer
of 1907 in potato fields all over the state and did noble service in kill-
ing off the potato beetles. These bugs were seen to be repeatedly
piercing the larvae of the beetles and sucking them dry. Indeed, we
were told by some farmers that this work was so effective on certain
farms as to make it unnecessary to spray for the | potato] bugs.”

Chittenden (1911) published a note in which he states: “Perillus
bioculatus, a predaceous bug, was reported by Mr. D. H. Shannon,
Appleton, Wisconsin, as having been noted killing the Colorado potato
beetle in August, 1908.”

Bethune (1911) reports as follows: “A very remarkable occurrence
of predaceous bugs has taken place in Southwestern Ontario during
the last few weeks. Correspondents in the counties of Dufferin,
Norfolk, Oxford, and Middlesex have sent in specimens of Perillus
bioculatus Fabr., and of its variety, claudus Say. The latter form was
described and figured in the Second Annual Report of the Entomological
Society of Ontario, published in 1871, under the name of Perillus
circumcinctus. These bugs, both in the imago and nymphal forms, are
destroying the Colorado potato beetles, both eggs, larvae, and mature
beetles, to such an extent that in some fields it is reported that hardly
any of the beetles are to be found, though the plants have not been
sprayed. They are quite abundant also at the College in Guelph and
other parts of the County of Wellington. The specimens have been
kindly identified by Mr. E. P. Van Duzee. He expresses surprise at
the species being found in this part of Ontario, as he considers it a
southern form, and is rarely known to be found as far north as the
State of Illinois.” The present writer is inclined to believe that the
early record mentioned above (1871) really applied to Perillus cicum-
cinctus as we know it now, a species which is sometimes found feeding
on the potato beetle but never in abundance.

Yothers (1911), in speaking of the article by Dr. Bethune, reports
as follows: “I also am glad to report the good work of this insect
in Michigan during the years 1908 and 1909. In 1908 it was sent in
to the Michigan Agricultural College several times, and each time
mentioned as killing the potato beetle. In 1g09 it was sent in quite
frequently, and from many localities. Several of the correspondents

STUDIES ON PERILLUS BIOCULATUS FAB.

on
wat

claimed that it was becoming so beneficial that spraying was hardly
necessary. . . . . There seems to have been a northward spread
of this insect, as it was not formerly known to occur as far north as
Illinois, and here we have it in 1908 and 1909 in Michigan, and in
Ontario in IgIt.”

Caesar (1912) publishes concerning Perillus bioculatus in Ontario,
as follows: “Perillus bioculatus var. clandus has been found in many
counties this year [1911]. Evidently it ranged almost all over the
southern and western part of the province, and, at least, as far east as
Toronto. In some fields it was present in large numbers and destroyed
many of the adult Colorado potato beetles and also the larvae.”

Nash (1912) published the following: “One of the Soldier Bugs,
Perilloides claudus, appeared in considerab'e numbers this year [1911]
in the potato fields, where it fed upon larvae of the potato beetle. Early
in August I found several of these bugs in the nymph stage feeding
on Tussock moth larvae. Claudus has never been a common insect
in Ontario, and why it should have become abundant and so generally
distributed this year is a mystery.”

In 1913 the writer found Perillus bioculatus abundant in Genesee
County, N. Y., at which time the present studies were begun. They
were carried on for four years in that locality. On making inquiries,
one farmer reported having noticed the bugs at work in his potato
field, at least two years earlier, or in 1911. As yet the species has not
been recorded from the New England states but there seems to be
no good reason why it should not move as far eastward as the Colorado
potato beetle has gone. At the present time the eastern limit of distri-
bution for the species must extend well into the eastern half of New
York, altho the most easterly record known to the writer is that of a
specimen taken at Ithaca, in 1915.

In Minnesota, since the summer of rg19, the writer has found
bioculatus fairly abundant in potato fields in the vicinity of University
Farm. Specimens have also been received from Mendota, Northfield,
St. Peter, Jordan, Center City, and St. Cloud. which would indicate
that the species is well distributed in the central eastern half of ihe
state. During the present year, 1923, Mr. C. E. Mickel has found
bioculatus present in potato fields at Quamba, Kanabec County;
Meadowlands, St. Louis County; and Thief River Falls, Pennington
County.

Methods of Rearing
For rearing Perillus, the ordinary type of jelly glass was found

to be a very convenient kind of cage. Holes punched in the lid fur-
nish plenty of ventilation and at the same time prevent the potato

56 NINETEENTH REPORT STATE ENTOMOLOGIST OF M{NNESOTA—IQ22

leaves from drying out too rapidly. One pair of bugs in a glass will
take very kindly to this arrangement, and when fed daily will produce
eggs quite as freely as in the field. After the bugs have been confined
in the jars for two or three weeks they become very tame, rarely try
to fly when handled, and show little fear as they walk about on the
hand or table. The female bug will lay her eggs on the potato leaves
when provided, but in the absence of these, will lay eggs readily on the
sides of the jar or on cheesecloth when it is supplied. The bugs
should be fed once or twice each day, altho they will get along if
neglected for a day. As fast as the eggs are laid they may be removed
to new jars for rearing. After the nymphs attain the third instar it
was found best not to keep more than six or eight in one jar. Unless
plenty of food is available at all times the bugs may develop canni-
balism. The unfortunate victim is usually attacked when in the act
of molting. However, when the bugs are not overcrowded this diffi-
culty rarely occurs. It was found necessary to clean the breeding
jars frequently, especially when rearing nymphs on larvae of the potato
beetle. For the purpose of keeping records, labels were pasted on the
sides of the jars, or attached to the lids.
Life History

Life cycle-——The adults of Perillus come forth from hibernation as
soon as the ground thaws out in the spring. By the time the potato
plants show above ground, and the first potato beetles appear, Perillus
may be found congregating in the potato fields. Their first meal in the
spring is sap from the potato plant, but after that their food is almost,
if not exclusively, the body fluids of potato beetles, their eggs and
larvae.

Perillus lays its eggs in masses on the leaves of the potato plant.
These hatch within five or six days, according to the temperature.
In the second instar the nymphs begin feeding on eggs or small larvae
of the potato beetle and as the bugs grow in size, large grubs and even
beetles fall as prey. The nymphs pass through five stages or instars
before attaining the adult stage; the average length of nymphal life
being 19 days during July and August, and 22 to 24 days during Sep-
tember. Upon reaching the adult stage the bugs begin mating, and
the females may start laying eggs six or seven days thereafter,

In New York, the first brood adults were found mating in the
field July 9 and 10, 1914. One pair of these laid eggs on July 16,
and from this lot adults matured August 9. This lot of bugs, or the’
second brood, laid eggs that matured the third brood during September.
Thus three broods of Perillus matured when the first brood eges were

on
N

STUDIES ON PERILLUS BIOCULATUS FAB.

laid about June 10. But one of the females that laid eggs early in June
also laid eggs as late as July 12. Thus the last eggs laid could not be
expected to produce adults of the first brood before August 6, and
the second generation adults by September 8 or 9. In western New
York, during 1914, three broods of Perillus were reared when the
overwintering females deposited their eggs before June 25, but the
same females continued to lay eggs after that date, and these later eggs
produced only two broods of bugs before the fall frosts drove beetle
and bug into hibernation.

In the latter part of September and early October, depending much
on the arrival of killing frosts, Perillus begins to seek hibernation
quarters. The bugs usually hide away under piles of leaves or rubbish,
altho many of them are found entering buildings. In fact, the habit
of entering buildings appears to be an important factor in the pres-
ervation of the species in northern localities.

Egg cluster. The eggs are normally deposited in a compact double
row (PI. I) on the upper surface of the potato leaf. Two egg masses
have been found on squash leaves, but on vines that were growing by
the side of a potato patch, thus they were probably accidental. It is
unusual to find eggs arranged in other than a double row, but when
disturbed the female bug may at times deposit an irregular mass. In
such case a partial third row of eggs is usually formed. Irregular egg
masses usually occur where the female has been forced to lay on small,
newly formed potato leaves. The average number of eggs laid in one
mass is estimated at 14, altho 24 and 26 eggs have been found in single
clusters, and one mass that was certainly unusual contained 33 eggs.
The large egg masses are usually laid following times when the female
goes three or four days without laying.

Oviposition. The overwintering bugs begin laying eggs in June,
very soon after the potato beetles make their appearance on the potato
leaves. The writer has observed the process of egg laying many times,
both in the field and in the breeding jars. When the female deposits
an egg, the tip of the abdomen first feels for the proper place, and
while the valves of the ovipositor are pressed close to the leaf surface,
they may be observed to swell and spread as the egg moves into posi-
tion. With the end of the egg placed firmly against the leaf surface,
the valves are moved upward and away, thus uncovering the egg
and leaving it standing on end in the desired position. The actual
movement of laying an egg requires only ten or twelve seconds. The
interval between deposition of eggs is usually from one and one-half
to two minutes, but the time for an individual bug rarely varies but

58 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

a few seconds between eggs. The eggs are deposited 1 ina double row,
the sides of the eggs in contact and glued together. *In placing the
eggs the female alternates in such a way that one row never has but
one egg more than the other. The eggs are yellow when first laid
but begin turning brown almost immediately; within ten minutes they
are blackish and by the end of an hour have attained their permanent,
deep black color. The average female lays a cluster of eggs each day
for the first five to seven days of egg production, following which
she usually begins to skip alternate days, while the last egg masses
deposited may be separated by periods of four or five days. Egg
masses of from 24 to 30 eggs are produced as the result of a female
going more than three days without laying.

Females that are kept segregated from the males frequently deposit
infertile eggs. Invariably such eggs are pale in color when laid and
never change to black. Females that are isolated from the males will
continue laying fertile eggs for several days, but in the case of several
such bugs it has been observed that after about two weeks, and the
deposition of several egg masses, the last eggs to be laid remain pale,
and in most cases never hatch. From this it would seem that the
spermatozoa had all been used, and the unfertilized eggs without such
stimulus remain pale in color. This observation has been made so
many times that it appears quite certain that the act of fertilization
produces changes in the egg which result in the black color. Of
perhaps three dozen pale egg masses observed, only one was found
to hatch part of the es
below under incubation.

Fecundity of the females. In Table 1 is recorded the egg laying per-
formance of nine female bugs selected as the most successful layers
among fourteen that were started during August, 1913. The number
of eggs laid in a mass is shown under the different dates as deposited,
and where two or three egg masses were laid on a single day, the
number of eggs in each mass is indicated. The death of a female
is indicated with “D” under the date when found dead. The bugs were
selected from reared lots, and isolated as pairs in cages, the records
showing the total number of eggs laid by each female. The males
lived as long as the females except in pair No. 5, of which the male
died August 29, while male No. 8 died August 16. The highest number
of eggs produced was 264 by femaie No. 8, while the lowest was 62
by bug No. 1, the latter dying somewhat prematurely. Averaging the
total number of eggs laid by these nine female bugs, it is found that
the average per individual is 144 eggs.

5

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Incubation. The period of incubation normally is five or six days.
In temperatures of 80°F. or above, five days were sufficient; with
lower temperatures, or from 70°F. to 78°F., six days elapsed before
the eggs hatched. One egg mass laid June 15 hatched on June 22,
making a period of seven days for June. Since the normal color
of the egg is black, one can not observe changes in the egg just prior
to hatching. In one instance at least, where abnormally pale eggs were
observed, it was possible to see changes of color in the eggs such as
may be observed in Pentatomid eggs that are normally pale in color.
This particular mass of 17 eggs, pale yellowish in color, was thought
to be infertile when laid on August 5. It was observed on August
to that certain eggs in this mass had turned dark orange red, and
the following day these hatched in a normal manner. The egg shells
left after hatching were pale in color, whereas the normal color of
Perillus eggs is black before and after hatching. The nymphs from
these particular eggs grew to maturity, and later two females from
the lot laid eggs which were of the usual black color.

Hatching. Vhe process of hatching requires about 10 or 12 minutes
from the time that the nymph can be observed cutting the lid at the
top of the egg. This is accomplished by means of the egg-burster
or hatching spine, a T-shaped chitinous structure which rests on the
anterior part of the head. By rotating within the egg, the emerging
nymph gradually cuts out a lid at the top of the egg, and this hangs
by a slender portion as if by a hinge, the hatching spine usually re-
maining attached to the lid. This lid is almost immediately forced up
by the head of the hatching nymph, and the act of emergence is ac-
complished by a series of pulsating movements of the body fluids.
The antennae and legs first appear closely appressed to the ventral
surface, but as soon as released the legs take an active part in freeing
the abdomen from the egg shell. Very shortly the newly emerged
nymph moves to one side of the egg mass and remains quietly huddled
with other newly hatched members. The gregarious habit is very
pronounced among nymphs in the first three instars, but in the later
stages the individuals become more or less scattered among the potato
vines.

Nymphal Instars

The length of the nymphal instars varies according to the tempera-
ture under which the bugs are reared, even when an abundance of
food is always at hand. Table 2 gives data on three lots of eggs reared
in glass jars under natural conditions of temperature prevailing at
that particular time of year. The 1913 and 1914 lots were reared

STUDIES ON PERILLUS BIOCULATUS FAB. 61

at Batavia, N. Y., while the 1921 lot was reared at St. Paul, Minn.
The data are arranged in a table similar to that given by Drake (1920)
for Nezara viridula Linnaeus.

Owing to higher average temperatures prevailing during July and
August, the average time from egg to adult in New York was found
to be 24 or 25 days. This time was duplicated by other lots reared,
but for which the exact time for individual instars was not always
kept. During September the period of development for nymphs is
more extended, some not completing their transformations before the
potato beetles enter the ground. From eggs which hatched Septem-
ber 2, 1913, and were reared in the laboratory, two individuals attained
the fifth instar during October. These were kept for hibernation
but both were found dead on November 1.

In Minnesota, where eggs were laid on June 15, 1921, adults did
not emerge until July 20, a period of 35 days. ‘In this lot it is possible
that growth was somewhat retarded because of irregular feeding,
still it is doubtful if the bugs would have found more food in the
potato patch during their eaily stages. From eggs deposited July 17,
1921, adults emerged August 15, a period of 28 days. Another lot
of eggs deposited July 18 developed adults on August 16, taking the
same number of days for development. From ihis it may be seen
that during the most favorable growing period of 1921 three or four
days more were required to mature adults at St. Paul than was the
case at Batavia, N. Y., in 1913 and 1914.

The minimum time observed for an individual bug to pass from
egg to adult stage was found to be 21 days, in 1914, at Batavia, N. A's

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STUDIES ON PERILLUS BIOCULATUS FAB. 63

Feeding Habits of Nymphs

During the first nymphal instar the bugs do not require animal
food. Several groups of newly hatched nymphs have been watched,
yet it seems rather doubtful if they even take sap from the leaf where
they remain quietly huddled. In this stage the nymphs rarely move
about, but spend the whole time in a closely formed group, apparently
awaiting the second day, when they molt and start in search of food.
During the second instar the nymphs feed largely on eggs or newly
hatched larvae of the potato beetle; but when these are not available
they may be observed attacking larger grubs, or joining in the feast
provided by an older nymph or adult bug. When a nymph success-
fully attacks a grub, it is usually joined by two or three of its brothers,
for increased numbers help materially in rendering the prey helpless.
Beginning with the third instar, individual nymphs will attack all
stages of the potato beetle grubs, and during the fourth and fifth
instars the same nymphs will attack mature beetles when the grubs
are not available.

The writer has reared Perillus from egg to adult on nothing but
mature beetles, but in this case the beetles were always rendered
helpless for the beneht of nymphs in the second and third instars.
More labor is necessary in rearing Perillus on beetles alone that when
grubs are available, yet it has been done in order to rear a fall gen-
eration of bugs after the potato beetle grubs have disappeared. By
this method of rearing, Perillus could no doubt be kept active and
breeding during the winter months if proper greenhouse facilities were
available.

To determine the amount of food consumed by individual bugs,
and thereby to estimate the economic value of Perillus, a good series
of bugs has been reared singly in jars and a record kept of the food
consumed. The following is an average for the food consumed during
the different stages of development: Stage I: no food, or possibly sap
from potato leaf; Stage II: 36 eggs of potato beetle; Stage III: 8 large
grubs; Stage IV: 12 grubs or beetles; Stage V: 14 grubs or beetles.
This gives a total of 36 eggs and 34 grubs or beetles, consumed by one
Perillus nymph during its immature stages. Within six weeks one
adult Perillus consumed 84 beetles and grubs, which combined with
the average amount of food taken by a nymph during its development,
gives a total of 36 eggs and 118 grubs and beetles destroyed by one
Perillus. Under field conditions both nymphs and adults undoubtedly
destroy many more eggs than were fed in the above experiments.

64 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

Habits of the Adults

When the adult Perillus comes forth from hibernation in the spring,
it has first of all a thirst for sap from the potato vine. ‘This is well
illustrated by describing the actions of two males and six females
which were observed in one lot confined in breeding cages. These
bugs were kept fairly inactive until May 20 when they were placed
in jars with potato beetles and exposed to outdoor temperatures. ‘These
bugs showed no great desire to attack the potato beetles provided,
and fed only sparingly when mutilated beetles were offered them.
On June 2, potato leaves containing eggs of the potato beetles were
introduced into the cages. Immediately all the bugs became active,
extending their beaks and probing around on the leaf surface, very
quickly inserting the rostrum in veinlets of the leaf in preference to
feeding on eggs of the potato beetle. Two of the bugs actually probed
at the egg masses of the beetle, then without paying further attention
to them, turned to feed on the leaf. Following a period of thirty
minutes all six bugs were still drawing sap from the potato leaves.
After thirty-five minutes, one of the males began paying attention
to a female, whereupon copulation soon took place but without the
female removing her rostrum from the leaf. Shortly after the thirty-
five minute period of feeding, two female bugs turned to feed on eggs
of the potato beetle. Following forty-five minutes of sucking sap
from potato leaves, the last of the six bugs turned to feed on eggs of
the potato beetle. Having finished their first meal on sap of potato
leaves, these bugs were never again observed to probe at leaves for
sap, altho they were watched closely each time fresh leaves were
placed in the cages. Among hundreds of bugs confined in breeding
jars during summer months, only two were ever observed in a feed-
ing position on a leaf, and it seemed doubtful if these bugs were actu-
ally drawing sap. One of these bugs stood with rostrum extended to
the leaf for nine minutes, but the movements were not such as usually °
occur with feeding, and the conclusion reached was that the bug merely
chanced to remain resting in that position. Why these bugs should
desire to draw gap from potato leaves only once, and that the first
chance they get after emerging from hibernation, is a mystery. One
can only guess that following hibernation sap is required for some
physiological function in the process of bringing the body fluids
back to normal from the condition of great density that obtained in
hibernation.

Adults of Perillus feed on eggs, larvae, and mature potato beetles,
apparently taking the stage that is most convenient. Beetles are

STUDIES ON PERILLUS BIOCULATUS FAB. 65

frequently attacked even when the more easily managed lavae are —
abundant. When advancing to the attack, Perillus approaches with
rostrum extended to the front, ready to insert the mandibles and
maxillae the moment a soft part of its prey is touched. To make
the insertion it seems necessary for the bug.to place its front feet on
the victim, thus gaining leverage to make the puncture, following which
the bug retires as far as the rostrum will permit. Once the insertion
is made the prey is securely held by barbs at the tips of the mandibles.
When attacking beetles the bug usually approaches from the rear,
inserting its rostrum near the tip of the abdomen or between sclerites
at the side of the venter. However, Perillus has occasionally been
observed standing on top of a beetle with tip of rostrum inserted at
a point where the head fits into the thorax. Having attained this position
it is difficult for the beetle to dislodge the predator.

In the potato field, the encounters between potato beetle and predator
are not without interest. If the potato beetle feigns death when at-
tacked, and tries to drop to the ground, the victim merely becomes
suspended from the tip of the bug’s rostrum. However, the beetle
usually tries to pull away by scrambling rapidly over the leaves of
the potato plant, dragging along the predator, who clings and pulls
back at every opportunity. When these tactics fail the potato beetle
may at times turn upon the enemy with mandibles snapping, trying
desperately to snip antennae or legs, when they can be reached; but
Perillus is very agile and usually manages to keep at rostrum’s length,
except at times when caged in small glass jars for breeding purposes.

In these encounters, all efforts of Perillus, following the insertion
of mandibles in the soft integument of the beetle, are directed toward
dislodging the feet of its prey and trying to keep the victim suspended
in mid air, where scrambling feet avail nothing. These encounters in
the potato field invariably result with Perillus the victor, while the
beetle or grub, following loss of blood, remains suspended over the
edge of a leaf and the predator finishes the meal undisturbed (Plate
En hie. 4.)

In restricted quarters, such as glass breeding jars, Perillus is at a
disadvantage and is not always able to keep the beetle at a safe distance.
Therefore when confining Perillus for breeding purposes, and using’
adult beetles for food, it was found best to snip the mandibles of the
beetle to prevent accidents to the bug, such as the loss of antenna or
leg, which eventually would result in premature death of the bug.

Mating habits. Following hibernation, and after both sexes have
had their first spring meal on sap of the potato vine, the bugs begin

66 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

mating almost immediately. The males are polygamous and_ the
females polyandric, thus it is necessary to keep the sexes isolated
from the time they emerge, if one wishes to control the mating of
individuals. The female will mate within a few hours following
the molt to the adult stage. The male usually approaches from in front,
applies the antennae with a vibrating motion upon head and antennae
of the female. This is followed by the male pushing with head beneath
that of female, very soon turning to one side and applying the head
to basal part of the female’s abdomen, raising her up from the normal
standing position; whereupon the male turns quickly, extending the
oedeagus to clasp with female, and if successful settles in a position
of end to end, the bugs facing in opposite directions. The sexes will
remain quietly in this position for hours at a time, and in the cages
the isolated pairs were found to remain in coitu from early evening
until late the next morning, and for successive nights during the period
when the female was producing eggs.

When the female is deprived of the male during a period of active
egg production, she will, after a period of about two weeks, begin laying
infertile eggs. In the field it has been observed that the sexes con-
tinue mating during the warm days of fall, just prior to the time when
frosts drive them into hibernation. ‘This raised the question whether
it is necessary, in the preservation of the species, that the males hiber-
nate and copulate with the females in the spring. Accordingly, during
the latter part of September, 1921, six pairs of copulating bugs were
isolated in jars and kept for hibernation. ‘Two of these females were
found alive the following spring altho the males had perished. With-
out further contact with a male, one of these females produced a mass
of 30 eggs on June 15, 1922, which were normal in color and hatched
on June 22. This female also laid 6 eggs on June 20, 15 eggs on June
21, and 10 eggs on June 26, all of which hatched. It therefore becomes
apparent that the female may occasionally carry the fertile eggs in
her body during hibernation and deposit them the following spring.

Length of life. Under favorable conditions, the adults which
mature during August and September of one year may be expected
to hibernate and live until the first part of June the following year.
The longest lived individual of which the writer has record was a
white female bug which emerged July 29, 1921, and lived until
June 18, 1922; making a period of to months and 21 days as an adult,
to which may be added 23 days of nymphal development. The usual
length of life is illustrated by a female that hatched on July 23, 1921,
became an adult on August 14, and lived until June 13, 1922, also a
female that hatched on August 28, 1921, and lived until June 25, 1922:

STUDIES ON PERILLUS BIOCULATUS FAB. 67

Ordinarily the male does not live as long cs the female but of two
males which hatched from the same egg mass on July 18, 1921,
one lived until June 4, 1922, and the second until June 28. In New
York, among the bugs that matured during September, 1914, at least
six females were alive in the cages as late as July 8, 1915. One of
these lived until July 13, and a second until July 15. The longest
lived individual laid eggs on July 12 (which hatched), was alive on
July 15, but was found dead on July 18.
Hibernation

With the cotaing of cool days in September, and the disappearance
of the Colorado potato beetle, Perillus bioculatus begins to seek hiber-
nation quarters for the winter. After the potato vines have been killed
by frost, many bugs have been found in depressions of the ground
beneath piles of the dead plants. Others leave the patch entirely and
fly in search of more suitable hibernation quarters. Individual bugs
are frequently found entering buildings, and such situations appear
to be most favorable as places for passing the winter successfully.
In northern regions, as in Minnesota and New York, a greater relative
abundance of Perillus may be correlated with nearness to cities and
villages where large numbers of bugs probably pass the winter safely
within buildings of various kinds. This statement is borne out by
the capture of a considerable number of specimens in buildings late
in the fall and then again in the spring as the bugs become active and
try to get out by way of windows. One bug has been found in hiberna-
tion beneath a burlap band which was wound around the trunk of an
apple tree for the purpose of collecting larvae of the codling moth.

A survey of potato fields and egg plants at University Farm, St.
Paul, was made on September 23, 1921, to learn what activities the
bugs displayed following frost and the drying up of the potato vines.
On that date the sun was shining and the temperature stood at 75°
Bugs were scarce in the dead and dried up potato fields, altho six
specimens of bioculatus were taken from spots where groups of potato
beetles were feeding on potato tubers. From egg plants which were
still largely green, 35 bugs were collected, of which two pairs were
taken in copulation. Bugs were found among the dead leaves at bases
of plants, others were active in the sunshine on the upper surface of
leaves. Several of the active specimens were found feeding on potato
beetles. Of the inactive specimens, five were found in one group
under dead leaves at the base of an egg plant. Others were found
two or three in a spot. Judging by these as well as other observations,

68 NINETEENTH REPORT STATE ENTOMOLOGIST OF MIN NESOTA—I1922

the gregarious instinct in Perillus is sometimes apparent in their
hibernation habits.

Under natural conditions the bugs come forth from hibernation
during the first warm days of spring, or very shortly after the frost
leaves the ground. At St. Paul, the earliest capture in the field was
that of a red male taken on the sidewalk on May 7, 1920. In New
York, the earliest field record was the capture of a female specimen,
on April 17, 1915, at Batavia. Several specimens have been taken in
buildings in April, and one bug was found active in February at the
window of a heated room.

The condition of the bugs when they go into hibernation has much
to do with the chance they have of passing the winter successfully.
This condition depends on the activities of the bug, the amount of
food taken, and the temperatures to which the bug has been subjected
just previous to the time when it becomes inactive for hibernation.
In handling various lots of bugs for hibernation it was noticed that
some were much more successful in passing the winter than others.
This may best be shown by giving actual figures on three lots of bugs
selected from a large series kept for hibernation.

Lot A contained 27 bugs, 10 males and 17 females, all of which
had matured in August. Beginning with September 1, these bugs,
confined in jars without food, were kept in a cool situation which dur-
ing September averaged between 60° and 68°F. On October 1 they
were placed in cold storage where the temperature was gradually low-
ered until by October 15 it had reached 41°F. The temperature of
the hibernating chamber ranged between 41°F. and the freezing point
until the following May. Upon examining the jars on October 19,
it was found that all were alive except 4 males and 3 females. An
examination of this lot of bugs on May 19, 1922, revealed the fact
that 3 males and one female had died since October 109, thus leaving 4
males and 12 females that had passed the winter successfully. These
figures show that 59 per cent of the bugs passed the period of hiberna-
tion and came forth alive.

Lot 207 was composed of 15 bugs, 7 males and 8 females, which
were kept active and given all the food desired as late as September
10. The bugs were then placed under similar conditions with Lot A.
An examination of these specimens on October 19 showed that 6
males and 3 females were dead. When examined on May 19, 1922,
only one male and one female were left alive. In this case only 13
per cent of the bugs survived the period of hibernation.

Lot 218 numbered 86 miscellaneous bugs collected in the field
on September 1 and 2. These bugs were kept alive in jars with plenty

STUDIES ON PERILLUS BIOCULATUS FAB. 69

of food all through September. By September 24, only 55 bugs were
left alive. It was found on September 28 that 11 more were dead.
Some of this number doubtless were bugs of the first brood which
had matured in July, while the remaining 44 must have been of the
second brood and of similar age to the preceding lots. On October
1 this lot of bugs was placed in cold storage beside Lot A and Lot 207.
An examination on October 19 showed that only 3 males and 6 females
were left alive. These figures indicate that 79 per cent of the bugs
died between September 2 and October 19. On May 19, 1922, only
one female was found alive.

On the basis of these observations it would seem that when the
bugs are kept active thoughout September, and with plenty of food
available, they are not in fit condition to go immediately into hiberna-
tion when cold weather overtakes them. The bugs that were kept
inactive and without food during September, in a temperature of from
60° to 68°F., were in the best condition by October to pass into the
hibernating stage.

Under natural conditions of hibernation the mortality of the
bugs must be very high during most years. It has been the writer’s
experience during six or seven years’ observation in potato fields in
New York and Minnesota, that very few bugs appear in the fields
the following spring, where the preceding fall they were very abundant.

Under natural conditions it appears that probably not more than 5
per cent of the bugs which go into hibernation come out safely in
the spring. In New York and Minnesota this may well be due to the
fact that many of the bugs seek hibernation in situations where their
fatal minimum temperature is reached during the cold winters. In
the spring of 1921 the largest number of bugs appeared in the field
that the writer has ever observed. The fall of 1920 was very favor-
able for the bugs that went into hibernation, and following this the
winter was unusually mild. The mild winter probably allowed many
bugs to hibernate safely in situations where during ordinary cold win-
ters their fatal temperature would have been reached. Such con-
ditions would seem to account for the greater abundance of the bugs
in the spring of 1921.

Determining the Fatal Minimum Temperature by the Thermoelectric
Method?

To determine the fatal minimum temperature of a hibernating

Perillus, experiments were performed utilizing the thermoelectric

2The writer is indebted to Dr. R. B. Harvey, of the Botany Department, University
of Minnesota, for the use of certain apparatus as well as for helpful suggestions in the matter
of taking temperatures by the thermoelectric method.

70 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

method for measuring temperatures. Using needle-type thermocouples
with potentiometer that records temperature in millivolts, it was pos-
sible to follow the internal temperature of individual bugs, as well as
the temperature of the surrounding air; to note the amount of under-
cooling which each could withstand, and finally the point at which
actual freezing took place. For details of this method see White
(1910), Harvey (1919), and Taylor (1920).

The bugs used in these experiments were all kept in the same
hibernating chamber at a temperature averaging very close to 4°C., from
October 15, 1921, until the hour of the experiment. The first attempt
to freeze hibernating bugs was made on March 28, 1922, when ether was
used to lower the temperature of the freezing chamber. This was
accomplished by drawing air through the ether which surrounds the
freezing chamber. With this particular apparatus the lowest tem-
perature which could be obtained was —17°C. Four different bugs
were reduced to this temperature and kept there for periods of fifteen
to thirty minutes, but without attaining actual freezing. The freezing
of undercooled tissue or liquids is always indicated by a rebound in
temperature to the actual freezing point. One of these bugs was placed
in the freezing chamber three different times, the periods totaling 45
minutes, during which the internal temperature was read at points be-
tween —15 and —17°C. This bug revived when warmed to room
temperature and was alive and crawling about the next day in spite
of the fact that it had been pierced with a thermocouple. The thermo-
couple, which had been reduced to the thickness of an ordinary pin,
was always inserted through the anus and extended to a point near
the base of the abdomen. The ether freezing chamber was discarded
at this point since it was evident that lower temperatures must be
reached in order to freeze the hibernating insects.

On the following day, March 29, carbon dioxide gas was used to
reduce the temperature in the freezing chamber. With this arrange-
ment one bug was cooled to a point where the internal temperature
was read at —26°C. but without freezing taking place. Unfortunately,
at this point the gas supply gave out, so it was not possible on that
date to find the limit of undercooling which Perillus could withstand.
It was two weeks before a new tank of carbon dioxide gas could be
obtained, so the next attempt to freeze the bugs was not made until
April 15. On this date some more of the hibernating bugs were taken
from cold storage, where they had remained all winter undisturbed,

STUDIES ON, PERILLUS BIOCULATUS FAB. 7i

at a temperature near 4°C. ‘The first bug selected was undercooled
to an internal temperature of —9.2°C., when a rebound occurred to
—2.08°C., thereby indicating the actual freezing point. The second
specimen undercooled was reduced to —g.74°C. when the rebound
occurred and indicated —2.24°C. as the freezing point. Four more
individuals were frozen but not one could withstand undercooling to
a point lower than —9.18°C. It might be added that all these specimens
were undercooled carefully to prevent shaking, which night cause in-
oculation prematurely, thus to determine so far as possible the limit
of undercooling in an undisturbed insect. All bugs that were actually
frozen, that is, in which a rebound in temperature took place, indicating
crystallization, were killed even tho removed immediately from the
freezing chamber.

Table 3 summarizes the data obtained from freezing ten specimens
of Perillus, the first six on April 15 and the last four on April 17.

TABLE 3

Rebound to:

Freeze Undercooled to: (freezing point)
Bug No. (trial) Gs ns

I Ist —Q.20 =P.
2nd —7.20 —2.01

2 Ist —0:74 —2.24
3 Ist —8.17 —1.79
4 Ist —g.18 —2.08
5 Ist ——f90) —1.70
2nd —7.70 —1.79

6 Ist —8.13 ste
2nd = 5\(62 —i.61

7 Ist —7.60 —1.52
2nd —7.60 —1.56

ard —6.79 —1.48

4th —8.13 —1.50

8 Ist —8.40 =e
2nd —7.86 =i.0s

3rd == 5 (0) See!

S Ist OS ae on
2nd —09.03 —2.13

3rd —8.50 —1I.90

4th —7.40 —1.90

5th se —1.90

6th —3.70 ——1.70

10 Ist —7.16 —1.74
and aad —1.88

¥ iP NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

In Figure I, temperature curves are plotted for the freezing of
bugs Nos. 1 and 2, and since the temperature curves for the remaining
bugs are very similar, these latter are omitted to prevent a confusion
of lines on the graph. The dotted line shows the temperature of the
air as recorded by a thermocouple placed at about three-sixteenths
of an inch to one side of No. 1. This curve indicates that sufficient
heat is given off during crystallization to raise the temperature of the
air in the immediate vicinity of the bug. Similar changes in tempera-
ture at the moment of freezing, as recorded by the air couple, were
noted in the freezing of other bugs, the amount depending on the dis-

; MINUTES,
C | ee eae es ae es ee chen ie

Fig. 1. The heavy lines are temperature curves for the freezing of bugs Nos. 1 and 2. The
dotted line gives temperature of the air as recorded by a thermocouple placed at about
three-sixteenths of an inch to one side of bug No. 1. This curve indicates that heat
was given off by the bug at the moment of freezing which was sufficient to raise the
temperature somewhat in the immediate vicinity of the bug.

STUDIES ON PERILLUS BIOCULATUS FAB. FS
tance of the couple from the bug. When lowering the temperature of
the freezing chamber at the rate shown on the graph, the temperature
of the bug showed a lag of about 1°C. This lag was more pronounced
when the temperature of the freezing chamber was lowered more
rapidly.

The surprising result of freezing the bugs on April 15 and April
17 was that not a single specimen could be undercooled to —10°C.
without actual freezing taking place, followed by the death of the insect.
As indicated above, it was not possible to freeze specimens at —17°
on March 28, and one individual was reduced to —26°C. on March 29
without actual freezing taking place. From this it is apparent that
certain changes took place in the hibernating bugs between March 29 and
April 15, altho the latter lot had been kept inactive at a temperature
near 8°C. It also would appear that there must be a periodicity in that
physiological condition which enables the bugs to withstand low tem-
peratures. Whatever the change in the resistance of the insects to low
temperatures, it was not due to physical activity or warming up of the
insect. It seems more likely that this change in resistance must be
related to time or age.

As yet, Perillus has not been frozen at intervals during the fall
as it goes into hibernation. Such experiments would indicate the
rate of change and adaptation to lower temperatures. But from data
presented above it is shown that if the bugs are to live through the
winter they must undergo changes in the fall and adapt themselves
to lower temperatures, something quite analogous to the well known
hardening of plant tissue in the fall. Certainly the bugs undergo a
drying out process, for examination of specimens during the winter
and early spring shows that the body fluids have been practically
eliminated. No doubt this concentration of body fluids and apparent
elimination of free water, is largely responsible for the ability of these
insects to withstand low temperatures during hibernation. This physical
condition, coupled with results obtained in freezing the bugs, bears
out the theory that the phenomenon of hibernation, which permits
undercooling to temperatures much below the freezing point, is pos-
sible only because of the high water-holding capacity of the body
substance; and this in its last analysis can be explained only on a
colloidal basis.

In the tabulated data above, it will be observed that some of the
bugs were frozen from three to six times, altho the bug was in each
case killed by the first freezing. Bug No. 9 shows rather clearly that
with successive freezing and thawing the freezing point is raised and

74 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

approaches that of water. Each time the bug is frozen a certain
amount of bound water is liberated, and a small amount of free water
will prevent much undercooling, for the presence of water causes early
inoculation and freezing. Then it would appear that the amount of
undercooling possible in an insect will depend (1) on the amount of
free water present and (2) on the density of the body fluids, or the
colloidal content.
Economic Importance of Perillus

From time to time enthusiastic reports have come from potato
growers in Michigan, Ontario, and New York, stating that Perillus
was becoming so abundant that spraying for the potato beetle seemed
unnecessary. In Genesee County, New York, the writer had oppor-
tunity to observe the result in a potato patch where the owner was
depending on Perillus to control the potato beetle. The first brood
of potato beetles had undoubtedly done considerable damage to the
potato vines before Perillus had developed to the point of abundance.
By the time the second brood of potato beetles had made their appear-
ance the predatory bugs were quite abundant and apparently destroyed
the eggs and young larvae of the beetle nearly as fast as they de-
veloped. However, a considerable number of potato beetle larvae were
able to reach maturity, and meanwhile these had caused some damage
to the vines. There was no doubt about Perillus doing good work
in checking the damage caused by potato beetles, yet the bugs were
not sufficiently numerous as to cause a scarcity of the beetles. Had
Perillus been as abundant at the beginning of the season as was the
case by September 1, very likely this predaceous bug could have been
relied upon to control the potato beetle.

Unfortunately there are certain factors in the life history of
Perillus which work against the increase of the species from one year
to the next. As brought out under the subject of hibernation, it was
estimated that not more than 5 per cent of the bugs present in the
field in September, hibernate successfully. Thus we find each spring
that Perillus is decimated in numbers, and not until the second gen-
eration has developed do they appear in numbers which would suggest
control of the potato beetle. Some years they appear more abundant
than others, and such seasons apparently follow a mild winter, as that
of 1920-21 in Minnesota.

Another factor which enters to prevent the increase of Perillus is
the fact that the bugs become poisoned by feeding on larvae and adults
of the potato beetle which have previously fed on sprayed potato
vines. Very early in the breeding work the writer learned that one

STUDIES ON PERILLUS BIOCULATUS FAB.

“NI
On

must be very careful about the selection of food for Perillus, and
never select grubs or beetles from vines which have been sprayed with
arsenicals. Perillus is apparently more sensitive to arsenic poisoning
than are the potato beetles, for one can go among the sprayed vines
and select grubs which appear healthy, but when fed to Perillus the
bugs die very shortly. This has been tested so many times that there
is no doubt in the writer’s mind that spraying for potato beetles
will also result in the death of nearly all Perillus in the field sprayed.
It is unfortunate that this is true, for otherwise Perillus might be
able to destroy all the beetles not killed by the spray. From this it
may be concluded that spraying for the potato beetle is also one of
the factors which serves to check the increase of Perillus in commer-
cial potato fields.

Perillus would prove more beneficial in the potato fields if they
were not so economical in their feeding habits. Unfortunately they
rarely waste food by giving up a victim that has been sucked to the
point of death. Once the potato grub or beetle has been overpowered,
Perillus feeds on the victim until it is sucked dry. Then again, when
one Perillus seizes a victim in the vicinity of other bugs, the latter
will join in sharing the food rather than each taking the trouble io
kill a different victim. Were Perillus as bloodthirsty as Podisus macu-
liventris Say, the species would be more efficient as a beneficial insect
in the control of the potato beetle.

The average amount of food consumed by an individual Perillus
has been indicated above under a discussion of the nymphs. It was
found that one nymph consumed 36 eggs and 34 grubs or beetles be-
fore attaining the adult stage. One adult Perillus destroyed 84 beetles
and grubs during a life of six weeks, which is not an uncommon period
of activity. Under field conditions the bugs would doubtless destroy
many more eggs of the potato beetle than were fed in the above
experiments.

Kinds of Insects Fed Upon by Perillus

There are a few records of Perillus bioculatus feeding on insects
other than the potato beetle. Nash (1912) in speaking of this pre-
daceous bug says: “Early in August I found several of these bugs
in the nymph stage feeding on Tussock moth larvae.” Marsh (1913)
says that “Perilloides bioculata Fab. a pentatomid, was frequently
found stabbing the partly grown Mamestra larvae.” The writer‘ has
placed a larva of Mamestra picta in a cage with several hungry speci-
mens of Perillus bioculatus and both nymphs and adults fed unon it.
In 1913 and 1914, while breeding for color inheritance in Perillus, the

76 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22
writer made tests to find if insects other than the potato beetle could
not be used as food for rearing the bugs. Among the insects that
were tried as food were larvae of Calligrapha from willow, the army
worm (Cirphis unipuncta Haw.), and Melanoplus femur-rubrum. In
these tests it was found that the young nymphs of bioculatus failed to
feed readily on the insects provided. Upon finding that the bugs
would not feed on the larvae of Calligrapha, a genus of beetles closely
related to Leptinotarsa, the idea of substituting food: was given up.
During the present year, 1923, while collecting on the high prairie
at Fort Snelling, Minn., the writer found both P. bioculatus and P.
circumcinctus feeding on the goldenrod beetle (Trirhabda canadensis
Kirby). Only one adult bioculatus was found in the field feeding on
this beetle, but three nymphs were collected and reared along with a
dozen nymphs of P. circumcinctus, all of which fed entirely upon
T. canadensis. Specimens of the goldenrod beetle were then placed
in jars with fifth-stage nymphs of P. bioculatus which had previously
fed only upon potato beetle grubs, and several bugs fed upon ihe
beetles provided. In the writer’s experience only two insects, the
potato beetle and 7. canadensis, have been observed in nature to serve
as food for Perillus bioculatus. Altho this Pentatomid has been found
to feed on certain Lepidopterous larvae, such choice of food appears
to be unusual for the species.

Technical Descriptions

The egg. The eggs are keg-shaped, but rounded off above and
below, an average egg being 1.2 mm. high and 0.88 mm. at its greatest
diameter. The upper portion of the barrel is distinctly marked with
irregular reticulations but these become invisible as the lines approach
the middle of the egg. The dorsal portion of the egg is encircled by
a row of semi-erect chorial processes, clubbed at their apices and bent
inward toward the micropyle. Within this ring is a smaller one sur-
mounting the top of the egg, a circular carina of nodular structure,

SS:
which on its outer circumference has a few supporting ridges that
radiate from it. (Plate I.) The chorial processes vary slightly in
number, and of several eggs examined, the number varied from 13
to 15. The color of a normal egg is deep black, but at times fertile
eggs may be found which are dark brown to blackish. Infertile eggs
are invariably pale, altho one pale egg mass was observed in which
several of the eggs hatched.

Nymphal instars. The immature stages are represented by five

nymphal instars, and upon molting for the fifth time the adult stage

STUDIES ON PERILLUS BIOCULATUS FAB. 77

is attained. The first two instars are very similar, the chief difference
being in size. During the third instar a difference in the red coloration
may be noted, for in some individuals the original tomato red color
is retained while in others the color may become orange red. In the
fourth instar the margins of the meso- and metathorax become sinu-
ated; in the fifth instar distinct wing pads are developed. (Plate I.)

First nymphal instar. Length 1.5 mm., greatest width 0.97 mm. ;
black: abdomen tomato red, with five dark patches on median line,
lateral margins of segments with heavily chitinized black spots which
join with similar spots on the ventral surface. The line formed by
posterior margin of metathorax practically transverse. Antennae four-
segmented ; tarsi two-segmented.

Second nymphal instar. Length 3 mm., greatest width 2.3 mm.;
similar to the first stage except in size.

Third nymphal instar. Length 5.2 mm., greatest width 4.3 mm.;
very similar to the preceding stage but in some individuals the tomato
red color may become orange red. The black color of the thorax may
frequently show distinct greenish reflections; also the sclerites of the
metathorax show a slight change in outline. (Plate I.) Tergites
of the abdomen finely punctate.

Fourth nymphal instar. Length 6.5 mm. to 7.5 mm., greatest width
4.5 to 5 mm. Distinguished from the preceding instar by the sinuated
outline of meso- and metathorax. The red coloration exhibits two
distinct phases; the tomato red color may be replaced by reddish
yellow but the dark markings remain much the same. The thorax is
usually blackish with a greenish luster. Punctures on abdomen more
distinct.

Fifth nymphal instar. Length 8 to 9 mm., width 5.5 to 7mm. In this
instar there are two distinct forms, the dark form in which the corium
of the adult will be black, and the light form in which the embolium and
inner half (or margin) of corium will be white or yellowish.

Dark form: Black, shining, with greenish luster, lateral margins
of prothorax and frequently the outer margins of wing pads at base,
yellowish to red; abdomen orange to red as in the preceding instar
but with the dark chitinized areas larger and more prominent. Punc-
tures of abdomen becoming fuscous or black. Wing pads strongly
developed, attaining hind margin of second abdominal tergite.

Pale form: Head, antennae, and legs black to greenish, tibiae more
or less pale on middle third; thorax and abdomen chiefly white or
yellowish, abdomen with dark spots similar to the preceding stage
but much reduced in size. Prothorax with a pair of black spots on

78 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

anterior half but smaller than the corresponding spots in the adult;
basal margin of pronotum blackish but not extending to lateral angles,
also broken at median line by pale. Wing pads greenish black, outer
margins broadly pale; mesonotum with a large pale area which sep-
arates the wing pads at base. (Plate I.)

The males are usually smaller than the females and can be separated
by differences found .in the genital segments. The greenish black
chitinized areas along median line of the tergites, the mediodorsal plates
of Hart (1919), each contain a transverse, curved suture connecting
laterally with the orifice of a scent gland. The first suture, near the
posterior margin of the third tergite, has at each lateral extremity
a minute and perhaps nonfunctional orifice. The fourth and fifth
tergites have more prominent sutures and the lateral extremity of each
bears a well developed orifice, apparently connected with a functional
scent gland. The fourth mediodorsal plate bears a suture but this is
probably without functional glands.

The adult. Male, length 8.6 to 10 mm., width at base of pronotum
5 to5.5mm. Female, length 10.5 to 11.5 mm., width at base of prono-
tum 6.4 to 6.7 mm.

Subelongate, somewhat broadly ovate; lateral margins of abdomen
visible from above, broad at middle and rounding sharply to apex.
Dorsum glabrous, smooth except for punctures. Head rather densely,
irregularly, and coarsely punctate; tylus and juga of equal length, the
former with a prominent subapical concavity, cuter margins of juga
moderately elevated. Rostrum reaching upon intermediate coxae.

Antennae: Segment I, length 0.41 mm., thickness 0.166 mm.; II,
T.05 mm., distinctly compressed and uniform in thickness, greatest
diameter 0.111 mm.; III, 0.83 mm., apex 0.17 mm. thick, slender at base
and gradually thickened to apex; IV, 1.11 mm., 0.166 mm. thick, nearly
cylindrical, slightly more slender at base and apex; V, 1.22 mm.,
0.166 mm. thick, cylindrical, tapering to slightly more slender at base
and apex.

Pronotum deeply, irregularly, and in places sparsely punctate; trans-
versely across middle of disk and between catli, sparsely punctate.
Lateral margins slightly sinuate, rather distinctly concave at middle,
anterior angles with small but apparent tubercle; basal angles bluntly
angulate, nearly forming right angles. Scutellwm more nearly flat
than in circumeinctus; basal half sparsely punctate except on black
area each side of median line, apical half rather closely and more finely
punctate. Pleurites of thorax coarsely, deeply, and irregularly punctate.
Ostiolar peritreme slightly elevated, shining, narrowly surrounded by

STUDIES ON PERILLUS BIOCULATUS FAB. 79

opaque, nearly crescent shaped in outline but the anterior margin recti-
linear, inner half with a shallow sulcus which deepens and leads into
the ostiole; ostiole situated slightly laterad of a line drawn through
lateral extremities of adjacent coxae. In circumcinctus the ostiolar
peritreme is narrower, its length equal to a little more than three times
the width. Hemelytra rather closely and finely punctate; membrane
extending slightly beyond tip of abdomen, dark fuscous to black.

Venter rather deeply but finely punctate, the punctures becoming
obsolete near median line. Ventral spine reaching to middle of pos-
terior coxae. Spiracles surrounded by black which forms a spot equal
to at least three times the diameter of spiracle. Males with a quadrate
area of dense, closely appressed, silvery pubescence each side of median
line on segments five to seven but limited to anterior margin on seventh
segment. Male genital claspers nearly triangular but the dorsal margin
distinctly sulcate in outline. In circumcinctus the dorsal margin of
genital clasper is practically rectilinear, the apex being rather broadly
rounded while in bioculatus the apex is acute.

Legs typical for the genus; the anterior femora with a prominent
tubercle or blunt spine situated on ventral surface, distant from the
apex a space equal to diameter of femur. Rarely a specimen may be
noted in which the tubercle is scarcely apparent.

Color Varieties

White color form. In this form the background is white with
markings of black and brown. Head brown, becoming black at base.
Antennae black, segments I, II, and base of III, brown to reddish.
Pronotum with basal one-third brown, frequently black, basal angles
not obscured ; callosities covered by black, each with a nearly quadrate
spot, separated by white on median line of disk; occasionally speci-
mens occur in which the black spots join, thus forming a transverse
black bar. Pleura black, usually showing ivory white irregularly on
disk of each sclerite. Scutellam with black longitudinally along middle,
becoming wider toward base and usually notched with white at middle
of base; the roughly punctate and depressed basal half of lateral mar-
gins also black. Clavius except basal angle, and outer half of corium
except apex, black; thus with embolium, inner half and apex of corium
white; inner half of corium frequently with white area much reduced ;
membrane always dark fuscous or black. Legs dark brown, tibia
becoming white on middle one-third, tarsi blackish. Venter black each
side of ventral spine but not extending laterally to the spiracle on

80 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

third segment; lateral submargins white, a prominent black spot sur-
rounding each spiracle; ventral portion of. fifth and sixth segments
black or only narrowly pale along median line, in the male partly coy-
ered by dense silvery pubescence, seventh segment black on basal half ;
genital segment black.

The white areas described for this form may with age become
red; the red color appearing first at basal angles of pronotum, tip of
scutellum, apex of corium, and ventral areas of abdomen. Adults
may at time of emergence have the pale areas partly red but in such
specimens the corium is always black. The white color form here
described always emerges from a fifth stage nymph which has the
mesonotum pale, as is shown on Plate I.

Yellow color form. <All the brown areas described for the white
form are here deep black, while the white areas are reduced somewhat
and replaced by yellow except on the tibiae. The corium is entirely
black; embolium yellow but becoming black apically. The black on
scutellum usually expanded, sometimes extending to base, and in dark
forms spreading laterally so that only the apex remains yellow. In
dark specimens the quadrate spots on pronotum may unite to form a
transverse black bar. In the female the black on venter unites to
form a lateral line, but situated somewhat beneath the black spots
enclosing the spiracles.

Red color form. The pattern of this form is similar to the pre-
ceding except that the yellow color is replaced by red. Red forms
occur in which the inner half of corium is red but in this case the bug
was a white form to begin with and the red color has been attained
during the adult stage.

The three color forms here described will include a high percentage
of those which one may expect to find. In a series of several hundred
specimens, however, it is possible to pick out specimens which show a
gradual transition from one form to another. (Plate III, fig. 3.) The
line of demarkation between the yellow and the red forms is not always
clear, for in many specimens the yellow gradually becomes orange,
and in fact that change actually takes place in living adults. However,
the colors never change once the adult has been killed and properly
dried. Ina large amount of material collected ten years ago, the yellow
and red colors have not faded in the least.

During the breeding experiments, in which the writer was trying
to establish pure lines of color, both yellow and red color forms were
reared from parents which were of the typical white color pattern.
Likewise, white color forms have been reared from both red and yellow
parents.

STUDIES ON PERILLUS BIOCULATUS FAB. 81

Nature of the Color Pattern

As stated briefly in the introduction, the writer began his studies
on Perillus with the idea of working on color inheritance in this
insect. After three seasons of breeding work trying to establish pure ~
lines of the white color form, and of a red color form, it became
perfectly clear that the color pattern of individual bugs was influenced
more by conditions under which they were reared than by characters
inherited from the parents. Since that time breeding experiments
have been carried on with the purpose of determining those factors
which produce the white color form, as well as the other extreme,
the red color form. It is hoped to publish elsewhere a more detailed
account of these experiments, but at the present time it is desired to
make a few preliminary statements of the resuits which will better
explain the nature of color varieties in Perillus and other Heteroptera.

The principal types of coloration found in insects have been dealt
with in a comprehensive paper by Hagen (1883). Hagen reviews all
the published statements regarding the nature of color in insects and
then contributes much from his own researches. This author divides
insect colors into: (1) dermal or cuticula colors; (2) hypodermal
colors. Tower (1903) published additional data, especially through
morphological studies on the hypodermis and cuticular layers. The
present writer has made morphological studies on the body wall of
Perillus and finds much in common with the figures published by
Tower, exhibiting details of the hypodermis and cuticula of Coleoptera.

The present studies on Perillus show that the black and brown
colors are located in the cuticula and are not subject to change, once
the adult stage has been attained. The white, yellow, and red colors
are located in the hypodermis and show through where black color-
ing matter is not present in the cuticula. The white color oecurs in
the absence of pigment granules in the hypodermal cells, while in the
yellow and red varieties the hypodermal cells are filled to a greater
or less degree with minute colored granules. The writer’s breeding
experiments with Perillus show that the accumulation of pigment gran-
ules in the hypodermis is influenced largely if not entirely by the
_ physiological activities of the bug. And the physiological activities of
the bug are governed very largely by the temperatures to which it 1s
subjected. With some insects the kind of food taken would be ex-
pected to influence the color, but in the case of Perillus the food uni-
formly consists of body fluids.of potato beetles and their larvae.

Explanation of Plate I

Plate I. Perillus bioculatus Fabricius, showing the five nymphal stages; also dorsal aspect of
eggs, and one egg in lateral aspect greatly enlarged; photograph from colored chart.
Two figures represent stage V, with yellow or red color form above and white form
below.

Explanation of Plate II

Fig. 1. Three fifth stage nymphs feeding on a large grub of the potato beetle.

Figs. 2-5. Showing the actions of two fifth stage nymphs as they strugsle for control of a
potato beetle grub. In figure 5 one nymph has placed all its weight on the other bug.

Figs. 6-7. A fifth stage nymph of the white color form is shown in feeding attitudes, sus-
pended largely by the hind legs.

Fig. 8. Three nymphs of the fifth instar attacking two large potato beetle crubs.
Fig.9. Seven fourth and fifth stage nymphs attacking a large potato beetle grub.

Fig. ro. Adult Perillus, of pedigree stock, feeding on a potato beetle from which the elytra
have been removed.

fig. 11. Second stage nymphs feeding on eggs of the potato beetle, enlarged (X3).

Fig. 12. Nymphs of the second and third instars feeding on newly hatched grubs of the potato
beetle.
Explanation of Plate II]

Fig. 1. Perillus bioculatus, white color form, enlarged (*4™%).
Fig.

ty

Perillus bioculatus, showing four color forms, enlarged (2); a, female, white color
form; b, female, red color form; c, female, \ellow color form; d, male, dark red
color form.

Fig. 3. A series of Perillus bioculatus illustrating the range of color pattern and size (slightly
reduced).

Fig. 4. Perillus bioculatus, red female, shown in characteristic feeding position with potato
beetle grub suspended in mid-air.

Figs. 5-6. Perillus bioculatus, male and female (X1%), shown for comparison with a pair of
Perillus circumcinctus (Stal) in figure ro.

Figs. 7-8. Perillus circumcinctus (Stal) attacking potato beetle grub; (fig. 7) the grub grasps
the plant’ stem and succeeds in throwing Perillus off its feet; (fig. 8) Perillus is
shown retaining its hold with rostrum after losing all foot-holds.

Fig.9. Podisus maculiventris (Say) in characteristic feeding position, with rostrum inserted
on the ventral side of a potato beetle grub. $

Fig. 10. Perillus circumcinctus, male and female (X14).
Fig. 11. Perillus circumcinctus feeding on grub of potato beetle (natural size).

PIC AAR sol

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86 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

The hypodermal colors are subject to change during the active
life of the insect. But the change of color in adult bugs is always 1n
one direction, from white to red, or from yellow to red. Once the
yellow or red color has been attained in the hypodermis of thé adult,
it remains throughout the life of the bug. Large numbers of adult
bugs have been kept under observation, at both high and low tem-
peratures, but in no case has the red color been reduced. The case 1s
different with growing nymphs. During the last three nymphal instars
the yellow color may change to red, or under other conditions, notably
high temperatures, the red of a fourth stage nymph may change to
yellow, and from that to white in the fifth instar. Thus the color
pattern of an adult is determined largely by conditions under which
the nymph has developed; for once having attained the adult stage,
the cuticular, or black color pattern, can not be changed, while the
hypodermal colors can change only in one direction, white to red, or
yellow to red as the case may be.

Change of Color in Adult

As brought out above, the change in hypodermal colors of the
adult Perillus 1s always in one direction, from white to red, or from
yellow to red. The change of color in the typical white color form
is of particular interest. In this form a yellow stage can scarcely
be detected, for the appearance of color in the white pattern is almost
immediately that of red. It is also noticed that the red color appears
first at basal angles of pronotum, tip of scutellum, apex of corium,
and ventral areas of the abdomen. From these points it progresses
outward until in the final stages all the white areas may appear deep
red. Male specimens turn red much more rapidly than do females,
and in fact it is difficult to keep white males as long as two weeks
without the red color developing. An examination of the hypodermis
at points where the red color is just appearing, shows that the granules
in the hypodermal cells are yellow at first but change very soon to
red, or at least by the time the cell is well filled with granules. It
appears that once these pigment granules have formed in the adult
hypodermis, reduction never takes place.

The typical yellow color form has the hypodermal cells filled with
yellow granules. Under certain conditions, notably temperatures of
78°F, or above, this color may be maintained unchanged. When the
temperature goes below 75°F. for a few days, the yellow color begins
to take on an orange-red cast, and if the bug lives six or seven weeks
it may become deep red in color. During hibernation there appears

STUDIES ON PERILLUS BIOCULATUS FAB. 87

to be no change in color of the bugs, and this is just as might be ex-
pected, since the physiological processes are at a standstill. It also
shows that temperature of itself can not affect changes in color but
only influences physiological processes during the active life of the
insect. However, rapid changes of color have been observed in the
two or three weeks prior to entering the state of hibernation, and
again during the period when the bug becomes active in the spring.

Relation of Temperature to Color Forms

Rather early in the breeding work, the rearing of a high percentage
of white color forms was correlated with high temperatures, both in
the laboratory and in field collections. This was rather forcibly im-
pressed on the writer during August, 1914, at Batavia, N. Y., while
breeding for pure lines of color in Perillus. The progeny of pair
No. 27 (yellow forms) began maturing August 3, and by August ro
twenty-one adults had emerged, all of which were yellow forms except
one, which was white. From August 5 to 10, inclusive, the weather
turned unusually hot, the temperature ranging between 83°F. and
95°F ., the minimum temperature not going below 76°F. in the labo-
ratory, and that only early in the morning. Of thirteen specimens
that matured on August 14 and 15, two males were yellow, while three
males and eight females were white. The appearance of white forms
in other breeding jars was-also conspicuous. From August 12 to 21
inclusive, the temperature remained much cooler, not going above
78°F. Between August 16 and 21, a total of thirty-nine yellow
forms and only four white bugs matured in a group of nine breeding
jars, which also included the progeny of pair No. 27. To the writer
this was rather convincing evidence that external conditions, notably
temperature, were having much to do with the color of the maturing
bugs. However, breeding for pure lines of color was not discontinued
at that time, but was kept up through the following year. Eventually,
all progeny of the white parents became yellow or red forms, this
occurring in the fall generation or in the spring. The progeny of
red parents all became yellow or white during the hot weeks of July
or August, and thus the parent type could not be maintained. Again
in 1921 an effort was made to breed for a pure line of white color
forms, but all the progeny from three pairs of white bugs became
either yellow or red during the second or early-fall generation.

The influence of humidity on color varieties of Perillus has not
been tested under conditions with absolute control, yet bugs have been
reared under two extremes of humidity where the temperature was
kept the same for both lots. This was accomplished by rearing bugs

88 NINETEENTH REPORT STATE ENTOMOLOGIST OF MIN NESOTA—1922

in glass jars, one lot in which the humidity was kept near the satura-
tion point by supplying fresh potato leaves regularly. These created
enough moisture to condense on the sides of the glass. The other
lot of jars contained only cheese-cloth for the bugs to crawl over and
thus was kept at the same humidity as the outside air. The bugs used
in these experiments were in each case selected from one egg mass,
part placed in the humid jars and part in the low humidity jars.
Both lots of jars, when kept at a temperature of 85°F. or higher,
matured a high percentage of white color forms, an occasional yellow
male, but never a red one. The results from these two extremes indi-
cate that humidity has little, if any, influence on the coloration of
the bugs. These experiments were carried on during two different
years but always with similar results.

Sunlight can scarcely be said to have a direct influence on the color
pattern, for the above experiments have been carried out in the labora-
tory where the bugs were never exposed to direct rays of the sun,
However, if the deposit of pigment granules in the hypodermis has
a direct relation to physiological processes in the bug, it- is very prob-
able that sunshine indirectly speeds up these processes. Many observa-
tions show that sunshine stimulates an insect to greater activity, as
do high temperatures even without sunshine. But at a given tem-
perature, sunlight probably speeds up the physiological processes and
produces what otherwise would be attained only at a higher temperature
in the absence of the sun’s rays.

Relation of Color to Sex

It was observed rather early in these studies that the male sex
averaged darker in color than the female, altho it is possible to find
white males as well as red females. An average population of 341
bugs, collected during August and September, 1913, gives the follow-
ing results:

White form Yellow form Red form
163 852 LOnS= 502 [2S eo aigas

From this it 1s observed that in a given population of bugs, reared
under the same average conditions, the male sex tends to be dark
in color while the females tend to be light. This difference in color
may very well be accounted for on a physiological basis. Since the
females must mature large numbers of eggs it seems reasonable to
suppose that the physiological processes go on at a higher rate than
is the case in the male. Male specimens of the white color form have
never been reared except with temperatures averaging above 82°F.

STUDIES ON PERILLUS BIOCULATUS FAB. 890

In the male sex, then, the only way of raising the physiological activity
to a point where white color forms appear, is by rearing the bugs
under high temperatures.

In Conclusion

It appears to the writer that Perillus bioculatus is, even among the
Hemiptera, an exceptionally good form for the study of color in an
insect. Bearing in mind that the food of this species is nothing but
the body fluids of the potato beetle or its immature stages, and the
quantity all that the bug desires, certain food factors that might influ-
ence changes in color are here reduced to a minimum.

Experiments show that low temperatures cause a greater deposit
of coloring matter in the hypodermal layer, and with this condition
a lower rate of physiological activity can be correlated, namely, longer
periods of growth for nymphs to reach the adult stage. Apparently
it is not temperature directly that affects the deposit of coloring matter
in the hypodermal cells, but the influence of temperature on the phy-
siological processes of the insect. With the ceasing of physiological
activity, as in hibernation, no changes in color can be observed.

Since a maximum amount of pigment is deposited in the body wall
under low temperatures (65°-75°F.), and the minimum amount de-
posited under high temperatures (85°-95°F.), it appears that increased
metabolism does not produce pigment, but on the contrary must con-
sume or otherwise dispose of the materials which under lower tempera-
tures are laid down as pigment in the body wall. In this connection
it is interesting to note that the most frequently found yellow and red
pigments, in both plants and animals, belong to the group known as
Carotinoids (Palmer, 1922). Furthermore, it has been shown by
several workers that the carotinoid pigments oxidize readily in animals
having a high rate of metabolism. Palmer (1922, p. 136) states: “The
normal cause of the disappearance of carotinoids from both plants and
animals is an oxidation. This is undoubtedly their ultimate fate in
animals unless they are secreted in the milk fat or egg yo!k (in fowls)
or stored up as adipose tissue and thus protected from oxidation.
Where the oxidative tone of the body is low, as in diabetes, coupled
in many cases with abnormally large intake of carotinoids, it is not
surprising that the pigments should appear in the tissues in abnormally
large amounts. ‘This is especially likely to be true of the epidermal
tissues inasmuch as the effect of eating carotinoid-rich diets in normal
persons shows that the subcutaneous glands can serve as an excretory
medium for these pigments.”

gO NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

Palmer (1922) also calls attention to the work of Physalix (1894)
who made chemical tests of the red pigment in one of the Heteroptera:
“Red coloration in the integument among some species of bugs 1s un-
questionably carotinoid at times, perhaps carotin itself. Thus, Phy-
salix (1894) extracted the red pigment [undoubtedly frem the hypo-
dermal layer} of the hemipter, Phyrrhocoris apterus, from two liters
of the insects. The pigment was deep red in carbon disulfide, yellow
in alcohol and ether, gave the lipochrome reaction with concentrated
H,SO,, and showed the absorption spectra of carotin. Physalix as-
serted that the pigment was carotin or a very closely related substance.”

In the case of Perillus, it is interesting to note that once the red
pigment is laid down in the hypodermis of the adult, it is never
diminished, thus it must be protected from oxidation. The case is
different in growing nymphs, for the yellow and red nymphs may at
times (under high temperatures) become distinctly paler even between
molts, altho the most rapid changes occur at the time of molting.
Adults and nymphs placed in alcohol (70 to 95 per cent) remain for
years (10 years) without losing their characteristic red and yellow
colors, while dried specimens preserved on pins and kept for the same
period retain the bright red and yellow colors nearly as in life.

The type of coloration manifested in Perillus bioculatus is exhibited
in some degree throughout the order Hemiptera. In numerous forms
examined, the yellow and red colors are all located in the hypodermis.
Correlating the prevailing temperatures with extensive collecting of
Neoborus amoenus (Reuter) and Horcias dislocatus (Say), indicates
that the color varieties of these species are influenced by temperature
in a manner similar to Perillus.

In the present work no attempt has been made to determine the
chemical nature of the pigments involved, but rather to arrive at some
understanding of the ecological factors which influence or govern the
production of color in the body wall of Hemiptera. To the biologist it
is worth something to know when and how the color pattern manifests
itself. It is left to the chemist to say what it is.

In 1923 the writer interested Dr. L. S. Palmer, chemist and
an authority on carotinoid pigments, in making chemical tests on the
nature of the red and yellow pigment found in the hypodermis of
Perillus bioculatus. Results of these experiments will be published
elsewhere, but it may not be out of place to state that all the tests
show the pigment to be nothing but carotin, the yellow or red color
depending on the concentration of this pigment. Furthermore, chemical

STUDIES ON PERILLUS BIOCULATUS FAB. OL

analysis of the blood of the potato beetle grub shows that the reddish
color is due entirely to carotin and, strangely enough, not a trace of
xanthophyll could be detected.

Perillus circumcinctus Stal

Another species, Perillus circumcinctus Stal, is sometimes found in
potato fields feeding on Leptinotarsa decemlincata (Say). This species
of Perillus has been the subject of some confusion as regarding its
identity and relation to bioculatus Fabricius.

Van Duzee (1904), in speaking of circumcinctus Stal, says: “I
have observed but little tendency to vary in this species.” The writer
is entirely in accord with this statement, and believes that all the varia-
tion mentioned by Zimmer (1912) was to be found only in specimens
of bioculatus Fabricius. Distant (1880, Biol. Centr. Am., Heter. I,
pl. 4, fig. 6) has figured an insect which he took to be a black form
of cicumcinctus Stal, but judging from the colored figure, the present
writer is satisfied that it represents an entirely different species. The
outline of the drawing as well as the coloration is not that of circum-
cinctus Stal.

Because of a long acquaintance with bioculatus Fabricius, the
writer desires to point out some of the differences between this species
and circumcinctus Stal. In Perillus circumcinctus the pronotum is
slightly longer and more convex, and this has been pointed out by
Van Duzee (1904) and Stoner (1920). The coloration of the antennae
can not be used for distinguishing the species, for in some pale forms
of bioculatus, segments I, H, and base of III, are brownish to reddish.
However, certain color aspects of circumcinctus appear to be distinctive,
and since the species is not variable in this respect, those points are
mentioned here. The spiracles appear black but are never surrounded
by a distinct black spot having a diameter greater than the spiracle
itself. In bioculatus the spiracles are inclosed in a black spot which
in diameter is at least equal to three times that of the spiracle. In
circumcinctus the pronotal disk is rarely transversely pale across middle,
that is, just behind the callosities, but instead there are two broad dark
brownish rays extending from the callosities to basal margin of disk,
thus leaving the lateral margins and a distinct longitudinal median ray,
pale. The dark color on dorsum is always more brown than black,
also shines with a bronze luster, while the pale areas never become red.
It is rare to find specimens of bioculatus so dark that the black color
on base of disk extends to join that covering the calli. There are at
hand three specimens of bioculatus, selected from perhaps one thousand
examined, where the black on base of pronotal disk has joined with

92 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

that on calli, but in these specimens the longitudinal median red ray
has likewise been eradicated, or does not extend beyond middle of
disk. Differences in the male genital claspers have already been des-
cribed under the technical description of Perillus bieculatus.

Notes on the Life History of Perillus circumecinctus

On June 28, 1923, the writer found Perillus circumcinctus 11 some
numbers on the high prairie at Fort Snelling, Minn. On that date
several nymphs and two adults were taken. These specimens were all
found on goldenrod where they were feeding on the goldenrod beetle
(Trirhabda canadensis Kirby). his beetle was very abundant on
certain large clumps of goldenrod and Perillus circumcinctus was con-
centrated in these places. Upon visiting the same locality on July 3,
twelve nymphs and five adults were taken. The nymphs were kept
for rearing and the last one matured July 1o. All specimens collected
were kept in cages and supplied with fresh goldenrod to which was
added numbers of Trirhabda canadensis, their favorite food. How-
ever, it soon became apparent that P. circumcinctus would not rear a
second brood, for no mating was observed among the several pairs.
By the end of July several individuals showed distinct indications that
they were preparing for hibernation. Fewer of the beetles were fed
upon and the bugs began to crawl under dead leaves and cellu-cotton
with which the cages were provided. One or two of the bugs were
active until August 10, on which date they were last observed to feed
on the goldenrod beetles. A collecting trip to the high prairie was
made August 3, and while the goldenrod beetle was abundant, not a
single specimen of P. circumcinctus could be obtained. No doubt all
the bugs had retired preparatory to hibernation, as was noted in the
breeding cages. At the present time, August 25, all the bugs, five
pairs, remain in a hibernating position, with legs drawn up and antennae
closely pressed against rostrum and ventral side of thorax.

‘These observations indicate that Perillus circumcinctus develops only
one brood each year. Mating will not take place until next spring.
This is very different from P. bioculatus, which species may frequently
be found mating on the last warm days of September, some days after
the last potato beetles have disappeared.

STUDIES ON PERILLUS BIOCULATUS FAB. : 33

LITERATURE CITED

Banks, NATHAN

1910 Catalogue of the Nearctic Hemiptera-Heteroptera. 8vo. Philadelphia,

1910. American Entomological Society. pp. 1-103-+(index) i-viil.
BETHUNE, C. J. S.

1911 Predaceous bugs. Can. Ent., xliii, p. 320, 1911.

1912 An enemy of the potato bug. Thirty-seventh Annual Report of On-
tario Agricultural College and Experimental Farm. 1911. Toronto,
1912, pp. 23-30.

Caesar, L.

1912 Insects of the season in Ontario. Forty-second Ann. Report of the

Entomological Society of Ontario. 1911. (1912) pp. 28-36.
CHITTENDEN, F. H.

1911 Notes on various truck-crop insects. U. S. Ent. Div., Bul. 82, pt. vil,
pp. 85-108. 1911.

1919 The striped cucumber beetle and its control. U. S. Dept. of Agr.,
Farmers’ Bul. 1038, 1919. pp. I-19.

Distant, W. L.

1880 Insects. Rhynchota. Hemiptera-Heteroptera. Vol. I, 1880-1893. pp.
I-xx-+1-462. 39 col. pls. Jn Biologia Centrali-Americana. 4to.
London, 1880-1900.

DRAKE, Cart J.

41920 The southern green stink-bug in Florida. Quarterly Bulletin, State

Plant Board of Florida, iv, 1920, pp. 41-94.
Fasricrus, Jou. CHrist.

1775 Systema Entomologiae sistens Insectorum classes, ordines, genera,
species, edjectis synonymis, locis, descriptionibus, observationibus.
8vo. Flensburgi et Lipsiae, 1775. pp. 1-832.

1781 Species Insectorum exhibentes eorum differentias specificas, synonyma
auctorum, loca natalia, metamorphosin adjectis observationibus, de-
scriptionibus. Tome II. Hamburgi et Kilonii, 1781. pp. 1-404.

1787 Mantissa Insectorum sistens species nuper detectas adiectis synonymis,
observationibus, descriptionibus, emendationibus. Tome II. 8vo.
Hafniae, 1787. pp. 1-383. [Hemiptera (Rhyngota) pp. 260-320.]

1794 Entomologia Systemetica emendata et aucta. Secundum classes, ordi-
nes, gener2, species, adjectis synonimis, locis, observationibus. Tome
IV. 8vo. Hafniae, 1794. pp. [i-vi]+1-472+ (index) 5.

1803 Systema Rhyngotorum secundum ordines, genera, species adjectis synon-
ymis, locis, observationibus, descriptionibus. 8vo. Brunsvigae, 1803.
pp. 1-x+1-314+ (index) I-21.

GILLETTE, C. P, and Baxer, Cart F.
1895 A preliminary list of the Hemiptera of Colorado. Colorado Agr. Exp.
Sta., Bul. 31, pp. 1-137, 1895.
GMELIN, JOHANN FRIEDRICH
1788 Caroli a Linne Systema Naturae. Tomes {-III, in 10 vols. 8vo.
Lipsiae, 1788-1793. [Insecta in Tome I, vols. IV-V. Vol. IV, pp.
1517-2224; V, pp. 2225-3020. Hemiptera in vol. IV, 1788, pp. 2041-
2224.]

04 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

GorzE, Jou. Auc. EPHRAIM
1778 Entomologische Beitrage zu des Ritter Linné zwoliten Ausgabe des
Natursystems. Zweyter Theil. 8vo. Leipzig, 1778. pp. iti-lxxii+
1-352. [Hemiptera pp. 1-352.|
HacEn, H. A.
1883 On the colour and the pattern of insects. Proc. Am. Acad. Arts Sci.
ser. 2, 1x, 1882, pp. 234-262. (1883).
Hart, CHARLES ARTHUR
1919 The Pentatomoidea of Illinois with keys to the Nearctic genera. Lhi-
nois Dept. of registration and education, division of the Natural
History Survey, Bul. viii, article vii, pp. 155-223, pls. xvi-xxi. 1919.
Harvey, R. B.
1919 Importance of epidermal coverings. Bot. Gaz., Ixvil, pp. 441-444, figs.
1-2.
Howakrp, L. O.
1900 A new western enemy of the Colorado potato beetle. Jn Some mis-
cellaneous results of the work of the Division of Entomology. U. S.
Ent. Div., Bul. 22, n. s., pp. 102-103. 1900.
KirKkaLpy, G. W.
1909 Catalogue of the Hemiptera (Heteroptera) with biologicel and ana-
tomical references, lists of food plants and parasites, etc. Vol. I:
Cimicidae. pp. XL+1-392. 8vo. Berlin, 1900.
Letuierry, L., and SEVERIN, G.
1893 Catalogue Général des Hémiptéres. I, Heteroptera. S8vo. Bruxelles,
1893. pp. x+286.
MarsH, H. O.
1913. The striped beet caterpillar. /1 Papers on insects affecting vegetables
and truck crops; “U. S. Bur. Ent., Bul. 127, pt. i, pp) Di-16s2One:
Nasu, C. W.
1912 Reports on insects of the year. Forty-second annual report of the
Entomological Society of Ontario. I9QII. pp. 17-19. (1912).
Osporn, HERBERT
1892 Catalogue of the Hemiptera of Iowa. Proceedings of the Iowa Acad-
emy of Sciences, i, pt. ii, pp. 120-131. 1892.
1894 Notes on the distribution of Hemiptera. Proc. Iowa Acad. Sci., i, pt.
iv, pp. 120-123. 1804.
PALMER, Leroy S.
1922. Carotinoids and related pigments, the Chromolipoids. The Chemical
Catalog Co., New York. 8vo. pp. 1-316.
Reni. ele
1908 Insects of 1907. Michigan Agr. Exp. Sta., Bul. 251, pp. 113-123. 1908.
PHyYSALIX, C.
1894 Recherches sur la matiére pigmentaire rouge de Pyrrhocoris apterus L.
Compt. Rend., 178, 1894, pp. 1282-1283.
Say, THOMAS
1852. Descriptions of new Hemipterous insects, collected in the expedition
to the Rocky Mountains, performed by order of Mr. Calhoun, Sec-
retary of War, under command of Major Long. Jour. Acad. Nat.
Sci. Philadelphia, iv, 1825, pp. 307-345.

STUDIES ON PERILLUS BIOCULATUS FAB. 95

1859 Complete writings of Thomas Say on the entomology of North Amer-
ica. Edited by John L. Leconte, M. D. 2 vols. New York, 1859.
ScHOUTEDEN, H.
1907 Genera Insectorum. Heteroptera. Pentatomidae. Fasc. 52, 1907, p. 37-
Stat, Caro.us

1862. Hemiptera mexicana enumerayit speciesque novas descripsit. Ento-
mologische Zeitung. Herausgegeben von dem entomologischen Vere-
ine zu Stettin. xxiii, 1862, pp. 81-118, 289-325, 437-462.

1870 Enumeratio Hemipterorum (part 1). Kongliga Svenska Vetenskaps-
Akademiens Handlinger, Band 9, No. 1, 1870, pp. 1-232.

1872 Enumeratio Hemipterorum (part 2). Kongl. Sven. Vet.-Akad. Hand.,
10, No. 4, 1872, pp. I-159.

Stoner, Dayton

1920 The Scutelleroidea of Iowa. University of lowa Studies in Natural

History, viii, No. 4, pp. 1-140, pls. i-vii. 1920.
TAyior, G. F.

1920 Some improvements on the needle-type thermocouple for low tempera-

ture work. Jour. Indus. and Engin. Chem., xii, pp. 797-799.
Tower, W. L.

1903 The development of the colors and color patterns of Coleoptera with
observations upon the development of color in other orders of in-
sects. Chicago Uniy., Decennial Publ., ser. 1, x, 1903.

UHLeErR, Pump REESE

1872 Notices of the Hemiptera of the western territories of the United
States, chiefly from the surveys of Dr. F. V. Hayden. In U. S.
Geol. Surv. Terr., Montana, etc. Prelim. rept., pp. 392-423.

1875 Report upon the collections of Hemiptera made in porticns of Nevada,
Utah, California, Colorado, New Mexico, and Arizona during the
years 1871, 1872, 1873, end 1874. United States Geographical and
Geological Explorations and Surveys west of the tooth Meridian,
Vol. v, Chap. xii, pp. 829-842, pl. xlii. Washington, 1875.

1876 List of Hemiptera of the region west of the Mississippi river, including
those collected during the Hayden explorations of 1873. /n Bul.
Worse Geols Geog, Sury, Terr; 1.1876; ' pp: 267-361, pls. .19-2r.
[Issued as a separate: pp. 267-280+15-95.]

1877. Report upon the insects collected by P. R. Uhler during explorations
of 1875, including monogrephs on the Cydnidae and Saldidae, and
the Hemiptera Collected by A. S. Packard, jr. M.D. Bul. U. S.
Geol. Geog. Surv, iii, No. 2, pp. 355-475.

1878 On the Hemiptera collected by Dr. Elliott Coues, U. S. A., in Dakota
and Montana, during 1873-74. Bul. U. S. Geol. Geog. Surv., iv, No.
2 pp 5038-502)

1886 Check list of the Hemiptera of North America. 8vo. Brooklyn,
1886. pp. 1-29+ (index) 3 pp.

1895 Observations upon the heteropterous Hemiptera of Lower California,
with descriptions of new species. California Acad. Sci. Proc., ser.
2, iv, 1893-4, pp. 223-205.

06 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

Van Duzer, E. P.
190, Annotated list of the Pentatomidae recorded from America North
ot Mexico, with descriptions of some new species. Trans. Amer.
Ent. Soc., xxx, 1904, pp. 1-80.
1917 Catalogue of the Hemiptera of America north of Mexico excepting
the Aphididae, Coccidae, and Aleurodidae. Univ. Calif. Publ., Div.
Ent. Tech. Bul., ii, pp. i- xiv-+-1-902. 1917.
Wuite, W. P.
1910 The thermoelement as a precision thermometer. Physical Review, xxx1,
p. 135.
Yoruers, M. A.
1911 Perillus claudus, a beneficial insect. Can. Ent., xliii, p. 418, 1911.
ZIMMER, JOHN Topp
1912 The Pentatomidae of Nebraska. Univ. Nebraska Studies, xi, No. 3,
IQII, pp. 219-251. 1912

PRELIMINARY NOTES ON THE MUTILLIDAE OF
MINNESOTA WITH DESCRIPTIONS OF
THREE NEW SPECIES?

By CLARENCE E. MIcCKEL

During the summer of 1922, in the course of an ecological study
of the sand dune area just north of Minneapolis, a large blowout was
found to be literally swarming with solitary wasps. In fact, these
insects were so numerous that it is doubtful if a square foot of ground
could have been found in the whole ten acres that did not harbor sev-
eral of them. The fauna included a great many species but the most
conspicuous, in point of numbers, belonged to the families Bembicidae,
Sphecidae, and Mutillidae. The Bembicids were especially numerous,
were to be seen everywhere, and the ground was honeycombed with
their burrows. The Sphecids were busy everywhere digging their
nests, bringing caterpillars for provisions, and putting the finishing
touches on their completed nests. Mutillids were universally present,
the females running over the ground, and the males flying overhead,
a foot or two above the ground. The number of Mutillids was rather
remarkable since they are usually seen in small numbers, one or two
individuals at a time. It was at once evident from an examination
of a few representative specimens that several species of Mutillids were
involved in the fauna of this sand dune area. Therefore an attempt
was made during the season to collect a large number, hoping thereby
to obtain specimens of all the species present. This collection and
other specimens taken in other parts of the state during the year and
a few collected in previous years, form the basis of this paper.

The blowout mentioned above is located in a sand dune area in
the most southern part of Anoka county, about one mile east of the
town of Fridley, and about two miles north of the Minneapolis city
limits. It is about ten acres in area, and is practically barren except
for a few spots which are sparsely covered with short vegetation.
There are several other blowouts in the same vicinity but none are so
large or have so abundant’a fauna of solitary wasps as this one. The
soil of the surrounding country is sandy but in most places is covered
with vegetation and is not blown about by the wind. The adjacent
territory is for the most part virgin prairie, altho on the southeast

1 Published with the approval of the director as Paper No. 391 of the Journal Series
of the Minnesota Agricultural Experiment Station.

98 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

side there is a small area of oak woods, and within a mile there are
stands of oak and other trees.

The Bembicids which were found so abundant belonged to the
species Bembix pruinosa Fox, and Microbembex monodonta Say; the
Sphecids were mostly Sphex argentatus Hart; while there were 17
species of Mutillids. Mutillids were so numerous that 625 specimens
were collected in eight hours. About 2500 specimens were taken here
during the season. Considering the abundance of the Mutillids, and
the enormous number of Bembicids in this situation, it would seem
probable that at least some of the species of Mutillids were para-
sitic in the nests of the Bembicids. While this assumption is entirely
hypothetical, no other species of insect appeared to be numerous enough
to furnish host material for such a large number of Mutillids. It 1s
hoped that during the season of 1923 some definite information can
be obtained regarding the life history and habits of the Mutillids in this
sand dune area.

The female Mutillid wasps at once attract attention, when seen,
because they are wingless and their bodies are covered with velvety
pubescence. The lack of wings gives them much the appearance
of ants and they are therefore commonly known as ‘“‘velvet-ants.”
The females are usually seen when running around over bare ground
and it is seldom that more than one is seen at a time. The males, which
are winged, may often be found visiting flowers, from which they
secure nectar. Both sexes are fond of sweet liquids and occasionally
are found in considerable numbers on plants where aphids are present,
where they congregate to partake of the honeydew which the aphids
excrete. Under such circumstances as this, and the conditions which
existed in the blowout described above, Mutillids may sometimes be
collected in large numbers. The female Mutillids have the reputation
of possessing very painful and severe stings. One species in the
southern states has received the name “cowkiller” on this account. In
collecting female Mutillids at the sand dunes it was found that large
numbers could be collected only by picking them up with the fingers
and placing them in the cyanide bottle. This necessitated vettiny stune
occasionally, but experience demonstrated that their sting was no more
painful than the injury caused by pricking one’s finger with a sandbur,
so that getting stung occasionally came to be regarded as a more or
less annoying, but not painful experience.

For the most part, these wasps are parasitic in the nests of solitary
wasps and bees, but the actual hosts for the various species of Mutillids
are known in only a comparatively few cases. Psecudomethoca sanbornii

STUDIES ON PERILLUS BIOCULATUS FAB. 99

Blake, which is found in Minnesota, has been reared from the cells
of a bee, Nomia patteni Cockerell. A species which occurs in Texas
has been reared from the nests of the mud dauber, Chalybion caeruleum
L. A species in Europe is said to be parasitic in the nests of bumble
bees. In recent years several species have been found to be parasitic
on the tsetse fly, Glossina morsitans Westwood, in Africa, and are
‘therefore of considerable economic imporance.

The Mutillidae are to be found in all parts of the world but are
much more numerous, both in individuals and species, in the arid and
semiarid regions of the tropics and subtropics. In the United States
the species are especially numerous. in the southwest. As one proceeds
northward the number becomes less and less, so that comparatively
few species are known from Canada. It has therefore been somewhat
remarkable to find 22 species of Mutillids in one year’s collecting for
Minnesota, and it is probable that other forms yet remain to be found.

Prior to 1918 no species of Mutillidae had been definitely recorded
from Minnesota. Washburn (1918) lists eight species of Mutillidae
as occurring in Minnesota but gives no definite dates or localities for
any of them. Four of these records, Dasymutilla ferrugata F., D.
macra Cresson, D. vesta Cresson, and Mutilla (Sphaerophthalina)
mutata Blake, are misidentifications. These species, so far as known, do
not occur in Minnesota. The specimens of Mutillidae from which the
figures in Professor Washburn’s paper were made have been examined
and their synonymy cited under the correct specific name. The present
material included 22 species representing four genera, as follows : Pseudo-
methoca, 3; Dasymutilla, 16; Timulla, 2; and Ephuta, 1. No doubt a
number of other species will be found to occur in the state when collect-
ing has been done in other localities. The following notes are intended
only as a preliminary survey of the family as it occurs in Minnesota,
and as an aid to the further investigation of these interesting wasps.

Two male Mutillids are described here which occur commonly
throughout the United States east of the Rocky Mountains, and which
have heretofore been confused in collections with other species. A more
detailed study of these two species and several related forms which
bear a superficial resemblance to them must be made before the average
worker will be able to identify any of them with certainty. This is
especially true of castor Blake, fenestrata Lepeletier, agenor Fox, and
several undescribed species. It is the intention of the writer to treat
these in a future paper.

100 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

KEY TO THE GENERA OF MINNESOTA MUTILLIDAE

1. Eyes round, strongly convex, usually polished.................+ esses sees 2
Eyes ovate, strongly faceted; in the males deeply emarginate within........ 3

2. First abdominal segment greatly enlarged toward the apex, completely sessile
with the second; second abdominal segment at the base scarcely wider than
the apex-or the hist, yd ee ees ovate cioera. bree Pscudomethoca Ashmead

First abdominal segment constricted at the apex, before the base of the sec-
ond; not completely sessile with the second; base of second abdominal
segment considerably wider than the apex of the first..Dasymutilla Ashmead

3. First abdominal segment completely sessile with the second; tergites of the
male without, or only the last one with a longitudinal carina. . Timulla Ashmead

First abdominal segment petiolate, not at all sessile, short, nearly cylindrical ;
third to seventh tergites of male with a longitudinal carina...... Ephuta Say

Genus PSEUDOMETHOCA Ashmead

Key to the species
Females

T Head spinose oridentate; bemeathiezia: iat a. - cer seit hehe rane canadensis Blake
Head not spinose,or dentate, bemea tiny eam itera) weit ele te fedecd = fel ee aed ee o
2. Propodeum with the posterior face more or less rounded into the dorsum,
not at a distinct right angle with the dorsum; metapleura micropunctate,
thinly: wlothedsawithiestlvety spies ert een eet eer sanbornt Blake
Propodeum with the posterior face at a distinct right angle with the dorsum;
metapleura sometimes very slightly micropunctate, not clothed with silvery

PILE! hp ee Mek ols sends Ses Be ok Cee genoa ant Seis: epiener ne ope propinqua Cresson
Males

r. Postero-lateralanglesvor head) dentate: 022 422 anes eee canadensis Blake

Postero-leterall ancles of head rounded’. hs.) chee ote oor 2

2. Abdomen ferruginous, with black pubescence................. sanbornit Blake

Abdomen black, with golden pubescence................-.-- propinqua Cresson

Pseudomethoca canadensis (Blake)
1871. Mutilla (Sphaerophthalma) canadensis Blake, Trans. Amer. Ent. Soc., iii,
25210.
1800. Photopsis cressonu Fox, Ent. News, i, 138 ¢ (not Mutilla cressoni
Blake).
1899. Mutilla canadensis Fox, Trans. Amer. Ent. Soc., xxv, 224 9 ¢.
Specimens examined: 9 August 1, 1922, Jordan, Scott county (A. T.
Hertig).
Pseudomethoca sanbornii ( Blake)

1871. Mutilla (Sphaerophthalma) sanbornii Blake, Trans. Amer. Ent. Soc., iii,
248 4.

1899. Mutilla sanborni Fox, Trans. Amer. Ent. Soc., xxv, 228 4.

1916. Pscudomethoca (Nomiaephagus) montivaga Bradley, Trans. Amer. Ent.
Soc, xiii, 320.9 (not of Cresson).

1918. Nonuaephagus sanborni Washburn, 17th Rept. State Ent. of Minnesota,

200.

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA IoL

Specimens examined: @ July 14, 1922, Fridley sand dunes, Anoka

county (A. A. Nichol); ¢ August 5, 1896, Gray Cloud Island.

This species, as well as the other two species of Pseudomethoca,

seems to be uncommon in this state. +

Pseudomethoca propinqua (Cresson)

1865. Mutilla propinqua Cresson, Proc. Ent. Soc. Phila., iv, 433 ¢.
1865. Mutilla montivaga Cresson, Proc. Ent. Soc. Phila., iv, 436 9.
1899. Mutilla montivaga Fox, Trans. Amer. Ent. Soc., xxv, 227 @ (in part).
1899. Mutilla propinqua Fox, Trans. Amer. Ent. Soc., xxv, 228 ¢.

rN)

Specimens examined: ? August 21, 1911, Fergus Falls (Stoner).

Genus DASYMUTILLA Ashmead
Key to the species

Females
Miamdithblesm trig emtatc.wractae ta aera Aersatic sasvo Giese: re amicus harmonia Fox
Mandibles bidentate, without a third tooth within..::..................-; 2
Lateral angles of vertex rounded, neither carinate nor tuberculate........ 3
lgateraleanclesmotmvertex: carimate one tuberculate a. + -e4-oe oe eerie 7
Head and thorax clothed with appressed, silvery pubescence...... canco Blake
rleadsand thoraxs withered or yellow pubescence. -cac-es an see seeoee nae 4

Third tergite entirely black pubescent, except the lateral margins; disc of

second tergite with sparse, fine, rather indistinct punctures.............
chlamydata Melander

Third tergite either with a median spot of silvery pubescence on the apical

margin, or the apical margin entirely silvery pubescent.................. 5
shhonassmwithywanscutellai | SGAles 1 5.cma serstee ch ko ls ee te oe elas NOhWwer
BhonaxmnnthOutucdescutellan tocaleey sn acer nem ce che che ssiaier ss coe ie ice ees 6
Apical margin of second tergite with black pubescence; no median spot of

SUlmelvanPUbeESCONCE Maen loc ane cee kara serete ser Peters avast or champlaint Rohwer

Apical margin of second tergite with a median spot of silvery pubescence. .
Sparsa Fox
Second abdominal tergite black, with two small basal, and two large,

Stay calanivO LyseSPOUSi we. aaem einen. Snckhael trac acura ayruct ee: quadriguttata Say
Secondeabdominaletereite tennis OUStn anaes ete ae ee eee 8
Front with a delicate carina extending from the base of the antennae to

Prema at: Clnle On reMer eviews a senaimaters ceeeln svete Metals nett ciate cariniceps Fox
HrontaniihoutwsuGlioa.. Caminatr yeresmtere ire tthe eae eh etNe we Meee deeet Pl oe fe 9

Second tergite with two small basal, and two large subepical, pale, ferru-
ginous spots, coarsely and closely punctate; posterior face of propodeum
TALIS O(N LACIE cae sate hte set ies «see wha aha hsahctord eway aia dhrers Rusty cypris Blake

Second tergite without spots, finely and sparsely punctate; posterior face of
HROpPoOdeummcoatselysiettculater sna ce ee awe Lmectelod. since > rugulosa Fox

102 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

Males

1. Second sternite with a longitudinal keel, surmounted by a crest of bristles...
asopus Cresson

Second isternite without a loneatudinalkeelsa..sssee see a: ener 2
2. “Body entirely black’. ..ihecrds ciciess cio ete a eiaiate = Gyo ie) s otsrers oer teleua ts eropoNore gibbosa Say
Body not entirely black; at least second abdominal segment reddish........ 3
3. Second sternite with a pit which is filled with bristles........ permista n. sp.
Second =stennite wathout Such) aap ite rue cxeesrye eiereyeleetore = alot) -letetey televene eee eee 4
4. Worsum of thorax with reddish pubescence.....:......:... bioculata Cresson
Dorsum ‘of thorax with’ black ‘pubescence... e. ssec. re ce ole ents eer i:
& Wegulae, impunctates .).:.Js see es qetelseeine «cuca ater meets che cko ey ecke te enameae 6
Tegulae punctate: Coaart sd hve weer cr aretoeae Fe os eit ere yee ole eee here agenor Fox
6. Abdomen black, except second segment ferruginous........... hirticula n, sp.
Abdomen castaneous, with black pubescence..................ddmetus Blake

Dasymutilla harmonia (lox)
1899. Mutilla harmonia Fox, Trans. Amer. Ent. Soc., xxv, 229 9.

Specimens examined: 49? July 27, 1922, Ft. Snelling (C. E. Mick-
el); 32 July 28, 1922, Fridley sand dunes, Anoka county (Paul
Gilmer ; 4? July 28, 1922, Fridley sand dunes, Anoka county (C. E.
Mickel) ; 2? August 8, 1922, Fridley sand dunes, Anoka county (A. T.
Hertig) ; 5 2 August 8, 1922, Fridley sand dunes, Anoka county (C. W.
Johnson) ; 2? Hennepin county; @ August 5, 1896, Gray Cloud Island.

This species is comparatively uncommon at the Fridley sand dunes.
It doubtless will be found in sandy situations over most of the state.

Dasymutilla esopus (Cresson)
1865. Mutilla asopus Cresson, Proc. Ent. Soc. Phila., iv, 435 ¢@.
18c9. Mutilla asopus Fox, Trans. Amer. Ent. Soc., xxv, 230 ¢@.
1918. Dasymutilla (Bruesia) asopus Weshburn, 17th Rept. State Entomologist of
Minnesota, 209.

Specimens examined: ¢ July 27, 1922, Ft. Snelling (C. E. Mickel) ;
é August 8, 1922, Fridley sand dunes, Anoka county (A. T. Hertig) ;
@ August 8, 1922, Fridley sand dunes, Anoka county (C. W. Johnson) ;
4 August 20, 1898, Gray Cloud Island.

This may possibly be the male of harmonia.

Dasymutilla caneo (Blake)
1879.. Mutilla caneo Blake, Trans. Amer. Ent. Soc., vii, 2
1899. Mutilla caneo Fox, Trans. Amer. Ent. Soc., xxv, 240 9.

Specimens examined: 992 July 21, 1922, Fridley sand dunes.
Anoka county (C. E. Mickel); 49 July 24, 1922, Fridley sand dunes,
Anoka county (Paul Gilmer) ; 692 July 28, 1922, Fridley sand dunes,
Anoka county (Paul Gilmer) ; 69 July 28, 1922, Fridley sand dunes,
Anoka county (C. E. Mickel); 199 August 8, 1922, Fridley sand

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA 103

dunes, Anoka county (A. T. Hertig); 139 August 8, 1922, Fridley
sand dunes, Anoka county (C. W. Johnson).

This species is easily recognized by its small size and the appressed,
silvery pubescence of the head and thorax.

Dasymutilla chlamydata (Melander)
1903. Mutilla chlamydata Melander, Trans. Amer. Ent. Soc., xxix, 299 @?.
1918. Dasymutilla ferrugata Washburn, 17th Rept. State Ent. of Minnesota, 200,
fig. 98 (not of Fabricius).

Specimens examined: 9? August 5, 1896, Gray Cloud Island ;
22 August 20, 1896, Gray Cloud Island; 29 September 3, 1899, Gray
Cloud Island; 59 August 1, 1922, Jordan, Scott, county (Av T. Her-
Moe © Aucust 25, 1922, Barden, Scott ‘county (©. E. Mickel);
9 July 17, Ramsey county ; 3? Hennepin county; 39 July 27, 1922,
Fr snelling (C. E. Mickel); 639 July 21, 1922, Fridley sand dunes,
Anoka county (C. E. Mickel); 309 July 24, 1922, Fridley sand. dunes,
Anoka county (Paul Gilmer) ; 13 2 July 24, 1922, Fridley sand dunes,
Anoka county (C. E. Mickel) ; 123 9 July 28, 1922, Fridley sand dunes,
Anoka county (Paul Gilmer); 146¢ July 28, 1922, Fridley sand
dunes, Anoka county (C. E. Mickel); 259 August 8, 1922, Fridley
Samy dunes Anoka county (AL T. Hertic) > 31 9 “August 8; 1922,
Fridley sand dunes, Anoka county (C. W. Johnson).

This is the most abundant species at the Fridley sand dunes. It
is found in sandy localities‘over a wide area in the middle west. The
individuals vary a great deal in size, the length varying from 7 to
15 mm. They also vary in color from a golden yellow to a deep
ferruginous. The series can be separated into two sections: those in
which the color is for the most part yellowish and which vary in
size from 7 to 10 mm.; and those in which the color is for the most
part ferruginous, and which vary in size from 12 to 15 mm. How-
ever, I can find no other tangible characters upon which to separate
them and for the present have designated all of them as chlamydata.
If a study of their life history can be made, it may throw some light
on this variation. It seems probable that this species is parasitic in
the nests of Bembix pruinosa Fox, or in those of Microbembex mono-
donta Say, or perhaps in both.

Dasymutilla bioculata (Cresson)
1865. AMutilla bioculata Cresson, Proc. Ent. Soc. Phila., iv, 431 ¢@.
1899. Mutilla bioculata Fox, Trans. Amer. Ent. Soc., xxv, 243 ¢.
1918. Dasymutilla bioculata Washburn, 17th Rept. State Entomologist of Minne-
sota, 200, fig. 97.

104 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

Specimens examined: ¢.July 7, 1921, Lake City (A. A. Nichol) ;
é August I, 1922, Jordan, Scott county (A. T. Hertig); ¢ Henne-
pin county; é June 30, 1922, Fridley sand dunes, Anoka county (A.
T. Hertig); 5¢ July 21, 1922, Fridley sand dunes, Anoka county
(C. E. Mickel) ; 166 July 24, 1922, Fridley sand dunes, Anoka county
(Paul Gilmer) ; 16 6 July 24, 1922, Fridley sand dunes, Anoka county
(C. E. Mickel) ; 83 6 July 28, 1922, Fridley sand dunes, Anoka county
(Paul Gilmer) ; 78 6 July 28, 1922, Fridley sand dunes, Anoka county
(C. E. Mickel) ; ¢ August 8, 1922, Fridley sand dunes, Anoka county
(A. T. Hertig) ;5¢ August 8, 1922, Fridley sand dunes, Anoka county
(C. W. Johnson).

This is the most abundant male Mutillid at the Fridley sand dunes.
It is probably the male of chlamydata. This series may also be
separated into two sections on the basis of size; (1) those varying in
length between 7 and 10 mm.; and (2) those varying between 12 and
15 mm. Both sections have identically the same genitalia and there is
apparently no character other than size upon which they may be
separated. I have therefore designated them all as bioculata.

Dasymutilla champlaini (Rohwer)
1912. Dasymutilla champlaini Rohwer, Proc. U. S. National Museum, xli, 461 ¢.

Specimens examined: @ August 5, 1896, Gray Cloud Island;
2 August 20, 1898, Gray Cloud Island; @ August 1, 1922, Jordan,
Scott county, (A. T. Hertig);, 2 August 25, 10922, Bardens Seo
county (C. E. Mickel) ; 59 July 21, 1922, Fridley sand dunes, Anoka
county (C. E. Mickel); 492 July 28, 1922, Fridley sand dunes, Anoka
county (Paul Gilmer); 119 July 28, 1922, Fridley sand dunes, Anoka
county (C. E. Mickel); g¢@ August 8, 1922, Fridley, sand) dune
Anoka county (A. T. Hertig); 132 August 8, 1922, Fridley sand
dunes, Anoka county (C. W. Johnson).

This is one of the more uncommon species at the Fridley sand
dunes. These specimens have been compared with the type of cham-
plaint and found to be identical. This species, together with sparsa,
is easily distinguished from related forms by the lack of a scutellar

scale on the thorax.

Dasymutilla sparsa (Fox)
1899. Mutilla sparsa Fox, Trans. Amer. Ent. Soc., xxv, 2409.
Specimens examined: @ August 1, 1922, Jordan, Scott county
(W. E. Hoffmann). This specimen has been compared with the type
of sparsa and found to be identical.

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA 105

Dasymutilla zella (Rohwer)
1910. Mutilla sella Rohwer, Proc. Ent. Soc. Wash., xii, 509.

Specimens examined, 29" July 27, 1922) Ft. Snelling o( Caw
Mickel) ; 792 July 21, 1922, Fridley sand dunes, Anoka county (C. E.
Mickel) ; 172 July 24, 1922, Fridley sand dunes, Anoka county (Paul
Gilmer); 1492 July 24, 1922, Fridley sand dunes, Anoka county
(C. E. Mickel) ; 302 July 28, 1922, Fridley sand dunes, Anoka county
(Paul Gilmer) ; 412 July 28, 1922, Fridley sand dunes, Anoka county
(C. E. Mickel); 422 August 8, 1922, Fridley sand dunes, Anoka
county (A. T. Hertig); 552 August 8, 1922, Fridley sand dunes,
Anoka county (C. W. Johnson).

This is the second most abundant female Mutillid at the Fridley
sand dunes. These specimens have been compared with the type and
found to be identical. This is not the same species as vesta Cresson.

Dasymutilla quadriguttata (Say)
1823. Mutilla quadriguttata Say, West. Quart. Rept., 11, 749.
1899. Mutilla quadriguttata Fox, Trans. Amer. Ent. Soc., xxv, 239 9.
Specimens exammed: 29 July 13, 1922," La Crescent’ (Cx E.
Mickel); 9 August 5, 1896, Gray Cloud Island.

Dasymutilla cypris (Blake)
1871. Mutilla (Sphaecrophthalma) cypris Blake, Trans. Amer. Ent. Soc., ili, 246 Q.
1871. Mutilla (Sphaerophthalma) mutata Blake, Trans. Amer. Ent. Soc., iii
247 Q.
1899. Mutilla cypris Fox, Trans. Amer. Ent. Soc., xxv, 240 9.
1916. Dasymutilla (Dasymutilla) cypris Bradley, Trans. Amer. Ent. Soc., xlii,
326 9.
1918. Dasymutilla cypris Washburn, 17th Rept. St. Ent. of Minnesota, 2009, fig. 96.
‘1918. Mutilla (Sphaerophthalma) mutata Washburn, 17th Rept. State Ent. of
Minnesota, 200. ;

Speemens, examined:) 9 June 14, . 1922, Rochester (GC. E:
Mickel); 49 August 5, 1896, Gray Cloud Island; 22 August 20,
1898, Gray Cloud Island; 32 August 1, 1922, Jordan, Scott county
(eel lenin) = 29s July.27, 1922, Ft. Snelling (GG. .E4.Mickel):
@ June 5, 1911, St. Anthony Park, Ramsey county; ¢ August 7,
1922, St. Anthony Park, Ramsey county (A. T.. Hertig); 10? July
21, 1922, Fridley sand dunes, Anoka county (C. E. Mickel); 9? July
24, 1922, Fridley sand dunes, Anoka county (Paul Gilmer); 592 July
28, 1922, Fridley sand dunes, Anoka county (Paul Gilmer); 49? July
28, 1922, Fridley sand dunes, Anoka county (C. E. Mickel); 149

,

106 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—192z2

August 8, 1922, Fridley sand dunes, Anoka county (A. T. Hertig) ;
229? August 8, 1922, Fridley sand dunes, Anoka county (C. W.
Johnson).
Dasymutilla cariniceps (Fox)
1899. Mutilla cariniceps Fox, Trans. Amer. Ent. Soc., xxv, 241 @.
1916. Dasymutilla (Dasymutilla) carimiceps Bradley, Trans. Amer. Ent. Soc.,
Sulit ween Ol

Specimens examined: 29 July 21, 1922, Fridley sand dunes,
Anoka county (C. E. Mickel); 2 August 5, 1922, Ramsey county
CAs LE eblentio:):

This is one of the rare species of Mutillids at the Fridley sand
dunes. Fewer specimens of this species were collected than of any
other. ;

Dasymutilla gibbosa (Say)
1836. Mutilla gibbosa Say, Bost. Journ. Nat. Hist., i, 2908 ¢@.

1899. Mutilla gibbosa Fox, Trans. Amer. Ent. Soc., xxv, 246 2.
1916. Dasymutilla (Dasymutilla) gibbosa Bradley, Trans. Amer. Ent. Soc., xlii,
322 4.
Specimens examined: ¢ July 18, 1911, Chisago county.
Dasymutilla rugulosa (lox)

1899. Mutilla rugulosa Fox, Trans. Amer. Ent. Soc., xxv, 240 9.
1916. Dasymutilla (Dasymutilla) rugulosa Bradley, Trans. Amer. Ent- Soc., xii,

1918. BRE bers. vesta Washburn, 17th Rept. State Ent. of Minnesota, 200, fig.
95 (not of Cresson).

Specimens examined: 9 July 13, 1922, La Crescent (C. E.
Mickel); 9 July27, 1922; Ft. Snelling. (C. jE. Mickel); (929)ialy mane
1922, Fridley sand dunes, Anoka county (C. E. Mickel); @ July 24,
1922, Fridley sand dunes, Anoka county (C. E. Mickel); 29 July
28, 1922, Fridley sand dunes, Anoka county (Paul Gilmer); ? Au-
gust 8, 1922, Fridley sand dunes, Anoka county (A. T. Hertig) ; 29
August 8, 1922, Fridley sand dunes, Anoka county (C. W. Johnson).

Dasymutilla agenor (Fox)
1899. Mutilla agenor Fox, Trans. Amer. Ent. Soc., xxv, 245 @.

Specimens examined: 4 July 27, 1922; Ft: Snelling» (Cage
Mickel); ¢ July 13, i911, Ramsey county; ¢ July 21, 1922, Fridley
sand dunes, Anoka county (C. E. Mickel) ; 134 July 28, 1922, Frid=
ley sand dunes, Anoka county (Paul Gilmer); 98 July 28, 1922,
Fridley sand dunes, Anoka county (C. E. Mickel); 10g August 8,
1922, Fridley sand dunes, Anoka county (A. T. Hertig); 106 Au-
gust 8, 1922, Fridley sand dunes, Anoka county (C. W. Johnson).

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA 107

Dasymutilla hirticula n sp.

1899. Mutilla macra Fox, Trans. Amer. Ent. Soc., xxv, 245 g (in part).

1916. Mutilla (Dasymutilla) macra Bradley, Trans. Amer. Ent. Soc., xlti, 329 ¢
(not of Cresson).

1916. Dasymutilla macra Rohwer, Hymen. Conn., Bull. 22, Conn. State Geolog.
and Nat. Hist. Surv., 624 (not of Cresson).

@. Black; second abdominal segment entirely ferruginous; length, 9mm.
Head black, about as wide as the thorax, sparsely clothed with long, erect, black,
pubescence; mandibles tridentate, i.e. acute at the apex end feebly bidentate
within; clypeus feebly bidentate medially at the cephalic margin, finely, confluently
punctate; scape closely punctate, with a sharp, longitudinal carina beneath; front
with strong, confluent punctures; vertex and genae punctate, but with the punc-
tures more separated than on the front; eyes round, very prominent.

Thorax black, sparsely clothed with long, black pubescence; pronotum, meso-
notum, end scutellum with strong, deep, confluent punctures; dorsum and pos-
terior face of propodeum coarsely reticulate; propleura with strong, confluent
punctures, cephalic margin rounded; mesepisternum and mesepimeron with large,
separated punctures, interspersed with a few very fine punctures; metapleura
polished, except the basal one-fourth, which is rugosely punctate; sides of propo-
deum polished, with a few scattered punctures; tegulae polished, with a few punc-
tures at the base.

Abdomen black, the second abdominal segment entirely ferruginous, clothed
with long, shaggy, black pubescence, except that on the apical four-fifths of the
second tergite dark orange-colored; first segment strongly petiolate; first tergite
with coarse, confluent punctures throughout; second tergite with elongate, sep-
arated punctures, the latter finer and closer on the apicel margin; tergites 3-6
with fine, close punctures, ultimate tergite longitudinally rugose; second sternite
with distinct, well-separated punctures: sternites 3-6 with fine, confluent punctures
at the apical margin; ultimate sternite closely, irregulerly punctate.

Wings dark; cell R4 indistinct.

Legs black, clothed with black hairs.

Holotype: ¢ July 28, 1922, Fridley sand dunes, Anoka county,
Minn. (C. E. Mickel), collection University of Minnesota.

Earasypes: CONNECTICUT: 4 4é° August's, 1915, Lyme. DIS-
DPaCGiy OF -COLUMBIA:...¢ .Atigust/ 21; . 18098, Washington:
Pe@meatess) 6 jily 20, 1976, Brinson.. LLULLNOIS: “6 July 15,
1894, Algonquin; ¢ July 19, 1895, Algonquin; ¢ July 20, 1895, Al-
eonquine “MASSACHUSETTS: 3) MINNESOTA: -¢ August
25 1oer, Houston, county (J. D.. Winter); .¢ July 27, 1922, Ft.
Snelling (C. E. Mickel); 23 July 28, 1922, Fridley sand dunes,
Anoka county (Paul Gilmer) ; 24 July 28, 1922, Fridley sand dunes,
mnaaka county s(C: HE. Mickel).: NEBRASKA: 204 August 16,
1912, Monroe Canyon, Sioux county (R. W. Dawson); 96 August
16, 1912, Monroe Canyon, Sioux county (FE. J. Taylor); ¢ August
6, 1908, Monroe Canyon, Sioux county (C. H. Gable); ¢ Bad Lands,

108 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

Sioux county (L: Bruner); oo ¢ August: wg; Glen, Siotx — county;
é August Q; 1912,;Halsey «CJ.;T! Zimmer)>:> NEW ofERSEY? 2a
August 16, 1404; Weymouth; ¢ July 16, 1901, Da"Costa;* ¢ Sep
tember 6, 1903, Hammonton; ¢ September 10, 1gto; Milltown;
6 June 24, 1906, Brown’s Mills Jc.; 3 July 13, 1912, Ramsey. NEW
YORK: °. 6° August “7, 1898, Pelham. ' NORTH CALRGER
é August 1,.1916,, Southern Pines... VIRGINIA: 3°¢. Awousimiss
1913,. Kearney (Wm. Middleton); g August 4, 1913, Ialls Church
(S.A; Rohwer):;‘¢ August4, 1913, ‘Falls Church —( Hy Bss hae
6 August 20, 1913, Falls Church (C: T: Greene); 13° Septenibente
1915, Falls Church (C. T. Greene); 6 August 28, 1913, Wiehle (Wim.
Middleton ).

Paratypes are deposited in the following collections: U. S. Na-
tional Museum, American Museum of Natural History, University
of Minnesota, University of Nebraska, State Entomologist of Penn-
sylvania, and the author’s.

The paratypes vary in length from 7 to 12 mm. This species has
much the same appearance as macra Cresson and is confused with
the latter in all collections of Mutillidae. It may be distinguished
from macra by the following characters: the second abdominal seg-
ment is entirely ferruginous, while in macra only the second tergite
is ferruginous; second tergite with the -punctures elongate and dis-
tinctly separated on the disc, more or less contiguous on the basal
third, while in macra the punctures are elongate and close on the
disc, and confluent on the basal third. The genitalia of this species
is distinctly different from that of macra. The types of Blake’s macra
and hispida have been examined and found to be quite different from
this form. The species macra Blake, so far as known, does not occur
in the eastern part of the United States.

Dasymutilla permista n. sp.

1899. Mutilla castor Fox, Trans. Amer. Ent. Soc. xxv, 244 @ (in part).

1903. Mutilla castor Melander, Trans. Amer. Ent. Soc., xxix, 302 ¢° (in part).

1916. Dasymutilla (Dasymutilla) castor Bradley, Trans. Amer. Ent. Soc., xii,
326 ¢@ (in part).

@ Black, second tergite more or less ferruginous; length, 12 mm. Head
black, about as wide as the thorax, sparsely clothed with long, erect, black
pubescence; mandibles tridentate; clypeus strongly bidentate medially on the
cephalic margin, very closely punctate; scape closely punctate, bicarinate beneath;
front closely, confluently punctate; vertex and genae with smaller, separated
punctures; eyes round and prominent.

Thorax black, sparsely clothed with long, erect, black pubescence; pronotum
and mesonotum with large, close punctures, those on the disc confluent; scutellum

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA 109

rugoso-punctate; dorsum and posterior face of propodeum reticulato-punctete ;
propleura with a few large punctures, interspersed with very fine punctures,
cephalic margin with a weak carina extending ebout half way from the ventral
margin to the humeral tubercle; mesepisternum and mesepimeron with large
punctures, separated on the ventral half, confluent on the dorsal half; metapleura
polished, with a few large punctures near the ventral margin; sides of propodeum
coarsely punctate; tegulae convex, polished, punctate near the besal margin.

Abdomen black, second tergite with two large, ferruginous spots, covering
almost the whole of the tergite; abdomen clothed with moderately dense, long,
erect, black pubescence, except that on the ferruginous spots the pubescence is
more or less yellowish: first abdominal segment strongly petiolate; first tergite
coarsely, confluently punctate throughout; disc of second tergite with moderate
punctures, separated by about their own width; tergites 3-6 very closely, moder-
ately punctate; pygidial area feebly longitudinally rugose; second sternite with
strong, separated punctures, medially with an ovate pit, about three times as
long as wide, closely packed with erect bristles; sternited 3-6, punctate at the
apical margin; ultimate sternite with strong, separated punctures.

Wings dark; cell R4 indistinct.

Legs black, clothed with black hairs.

Holotype: & July 28, 1922, Fridley sand dunes, Anoka county,
Minnesota (C. E. Mickel), collection University of Minnesota. —

Paratypes: COLORADO: ¢ August 7, 1899, Durango; g Au-
Susts iO, pro04, soterline 6. CONNECTICUT: «16 sAtieust 25}
1g09, Lyme (A. Champlain); ¢ August 28, 1909, Lyme (A. Cham-
plain). ILLINOIS: ¢ July 12, 1895, Algonquin; ¢ July 15, 1894,
Algonquin; 26 July 22, 1894, Algonquin; ¢ July 1, 1901, Belvidere
Wy ao. riereeyer dtuse4, Hayanay? KANSAS s\( '3) July ira Riley
county (Popenoe); 24 July 17, Riley county (Popenoe) ; 34 July 109,
Riley county (Popenoe); ¢ July 21, Riley county (Popenoe) ; 24
July 22, Riley county (G. A. Dean); ¢ July 25, Riley county (G. A.
Dean); ¢ August 9, Riley county (Popenoe); ¢ August 9, Riley
county (J. B. Norton); ¢ August 25, Riley county (G. A. Dean) ;
26 August 27, Rooks county; 3 ¢ September 1, Riley county (Pope-
noe) s/o sjulyen7;, 1901;) Wellsville.» LOUISIANA: | 6¢.2-MASSA=
CHUSE TERS igdvAucust 18, 1890, Elyannisport: (J. Ie-Zabriskie):;
é August, 1898, Woods Hole (C. L. Marlatt), MINNESOTA:
per iilyas, 1922, Ia vCrescent (C: Ey Mickel)aserAueust 1 7;| 1900;
Gray Cloud Island; $ August 20, 1898, Gray Cloud Island; 84
July 12, 1921, Gray Cloud Island (Wm. A. Riley); ¢ August 0,
1899, St. Anthony Park, Ramsey county; ¢ July 13, 1911, Ramsey
county; ¢ July 21, 1911, Washington county; $¢ August 2, 1922,
St. Peter (R. R. Holland); ¢ July 6, 1910, Hennepin county; 114
July 27, 1922, Ft. Snelling (C. E. Mickel); 26 July 21, 1922, Frid-
ley sand dunes, Anoka county (C. E. Mickel); 8 July 24, 1922,

II0O NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

Fridley sand dunes, Anoka county (Paul Gilmer) ; 24 July 28, 1922.
Fridley sand dunes, Anoka county (Paul Gilmer); ¢ August 8, 1922.
Fridley sand dunes, Anoka county (C. W. Johnson). NEBRASKA:
6 July, 1903, Meadow; 8 July 29, 1914, Louisville (E. G. Ander-
son); ¢ July 30, 1914, Louisville (H. A. Jones); ¢ July 30, 1914,
Louisville (E. G. Anderson); 3 July 31, 1914, Louisville (E. @
Anderson); ¢ July 31, 1914, Louisville (H. A. Jones); 56 August
I, 1914, Louisville (E. G. Anderson); ¢ August 2, 1914, Louisville
(H..A: Jones); 3¢ July, Emcoln; ¢ July 4, 1920, Lincoln (CR. W:
Dawson); ¢ July:a11; 1920,. Lincoln .(C. -B.: Philip); 173 Julyeae
4920, Lincoln (C. “EE. Mickel); 54> July 18, 1920; Lmecomn(RawWe
Dawson); ¢ July 30, 1909, Lincoln (C. H. Gable); & August 26,
roo1, Lmeoln. (W.. DY Pierce) ; 26 - June, 1887; "West, Hotinteees
June 24, West Point; ¢ August 20, 1906, Broken.Bow (H. S. Smith) ;
é August 8, 1912, Halsey (J. IT: Zimmer) 3.23 -July-22; 1902) oak
county (W. D: Pierce); 8¢ July, Pine Ridge. NEW JERSEY ig
South. Amboy; @ September 2, 1901; Lucaston’;: oul ss ream
Manunruskin;’ @ July 30; 1912, Ramsey... NEW “YORKa iar
28, Fisher’s Island; ¢ Flatbush, Long Island: +2 July 21, "iro0e
Cold Spring’s Harbor, Long Island; ¢ July 23, 1900, Cold Spring’s
Harbor, Long Island; 2¢ July 24, 1900, Cold Spring’s Harbor, Long
Island; ¢ July 27, 1900, Cold Spring’s Harbor, Long Island. PENN-
SYLVANIA: 2¢. July 24, 1902, Castle Rock (E. Daecke) 5d July
5, Rockville;. 3g. July. 29; ‘Rockville; ¢ Mount Hope’ TEXAS:
6 June 21, 1905, Quinlan (F. C. Bishopp); ¢ July 7, 1906, Bryan
(J. C. Crawford); 3 . ume 28; 1905;. Rosser (©. "Re jones) wens
August 22, 1907, Overton (W. W. Yothers); ¢ Hockley. VIR=
GINIA: + @ July 13,:191r,. Vienna (C. W. Hooker) 32:6 Seprenibes
i, 1915, Ralls Ghureh (CFT. Greene),

Paratypes are deposited in the following collections: _U. S. Na-
tional Museum, American Museum of Natural History, University
of Minnesota, University of Nebraska, State Entomologist of Penn-
sylvania, Kansas Agricultural College, Colorado Agricultural College,
and Oregon Agricultural College.

The paratypes vary in length from 8 to 16 mm. In a few the
ferruginous color extends on to the second sternite and the first ab-
dominal segment.

The type of castor Blake has been examined and found to be a
unique from Texas. The specimens designated as Mutilla castor
Blake in collections consist of several distinct species. This is ane

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA Til

of the most common species found in those series. Superficially this
is very much like agenor Fox, fenestrata Lepeletier, and several other
species. The relationships of these species will be treated in a future
paper.
Dasymutilla admetus ( Blake)
1872. Mutilla (Sphacrophthalma) admetus Blake, Trans. Amer. Ent. Soc., iv,
74 ¢-

1899. Mutilla admetus Fox, Trans. Amer. Ent. Soc., xxv, 245 ¢.

Specimens examined: ¢ July 28, 1922, Fridley sand dunes, Anoka
county (C. E. Mickel).

‘

Genus TIMULLA Ashmead

Key to the species
Females

1. Thorax with a distinct scutellar scale; last three abdominal segments

ROLeLG Ess fire eects eee ees, Mee vray hare nents eect rasan So ope gee Neate are briaxus Blake
Thorax without a scutellar scale; last three abdominal segments red......
SAG t ES Chak lad OS aes ERR ALCO Sc IEC ce Ona RnR ed Aer EE eH Cicer euterpe Blake

Timulla briaxus (Blake)
1871. Mutilla briaxus Blake, Trans. Amer. Ent. Soc., ili, 227 ¢.
1909. Mutilla (Timulla) briaxus Rohwer, Trans. Amer. Ent. Soc., xxxv, 132 9.
1916. Mutilla (Timulla) briaxus Bradley, Trans. Amer. Ent. Soc., xlli, 207 ¢ 9.
Specimens examined: ¢ July 7, 1921, Lake Gity (A. A. Nichol);
@ July 18, 1922, Newport (A. A. Nichol); 2 July 18, 1922, New-
port (C. E. Mickel) ; ¢ June 27, 1921, Minneapolis (A. A. Nichol).

Timulla euterpe (Blake)
1879. Mutilla euterpe Blake, Trans, Amer. Ent. Soc., vii, 249 @ .

Specimens examined: @ Hennepin county.

A specimen of this species in the University of Minnesota collec-
tion bears the above locality label. Whether the data are authentic
or not, can not be determined. The species has been known hereto-
fore only from the unique type collected in Florida. There is, there-
fore, some doubt as to whether this species actually occurs - in

Minnesota.
Genus EPHUTA Say

Ephuta conchate n. sp.

@. Entirely black; length 9 mm. Head coarsely, confluently punctate, with
appressed and erect, short, whitish pubescence; two low carinae diverge from
between the antennae, then are subparallel to a point about half way to the
margin of the clypeus, here they flare outward to the margin of the clypeus;

112 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

the space thus enclosed finely rugose at the base, polished at the epical margin;
first joint of flagellum about three-fourths the length of the second; lateral
ocelli a little more than four times their diameter from the inner margin of the
eyes.

Pronotum, mesonotum, end scutellum very coarsely, confluently punctate,
with semi-erect, short, sperse, whitish pubescence; cephalic surface of pronotum
punctate; dorsum of propodeum very coarsely and deeply reticulate, with a sub-
rectangular, median enclosed space, separated from the posterior surface by a
sharp ridge; posterior surface of propodeum reticuletely punctate; propleura
confluently punctate, the cephalic margin sharply carinate; humeral angles promi-
nent, almost dentate; mesepisternum and mesepimeron reticulately punctate,
clothed with dense, semi-erect, whitish pubescence ; metapieura polished; sides of
propodeum coarsely reticulate; tegulae very large, shell-shaped, elongate convex,
not ridged longitudinally, irregularly punctate and hirsute, the lateral and apical
margins polished and impunctate.

Abdomen clothed with spare, erect, whitish pubescence; first and second
tergites with a band of dense, eppressed, whitish pubescence at the apical margin;
first segment cylindrical, coarsely punctured, with a keel beneath; second segment
with large, deep, contiguous punctures above and beneath; remaining segments
distinctly and closely punctate; tergites 3-7 with a median longitudinal] keel.

Wings subhyaline.

Legs black, clothed with whitish pubescence; calcaria whitish.

Holotype: 8 July 27, 1922, Ft. Snelling, Minnesota (A. A.
Nichol), collection University of Minnesota.

This species is apparently related to tegulicia Bradley. It may be
distinguished from that species by the form of the carinae on the
clypeus and the absence of a longitudinal ridge on the tegulae.

BIBLIOGRAPHY
BLAKE, C. A.
1871 Synopsis of the Mutillidae of North America, Trans. Amer. Ent, Soc..
iii, 217-265.
1872 Additions to the “Synopsis of North American Mutillidae,” Trans.
Amer, ‘Ent. Soc. 1v, 71-76.
1879 Cetalogue of the Mutillidae of North America, with descriptions of
new species, Trans. Amer. Ent. Soc., vii, 243-254.
Brapiey, J. C.
1916 The Mutillidae of the Eastern United States, Trans. Amer. Ent. Soc,
xlii, 309-336.
Cresson, E. T.
1865 Catalogue of Hymenoptera in the collection of the Entomological
Society of Philadelphia, from Colorado Territory, Proc. Ent. Sac.
Phila., iv, 428-442.
Foxy Ws J:
1890 Three new species of aculeate Hymenoptera, Ent. News, i, 138.
1899 The North American Mutillidae, Trans. Amer. Ent. Soc., xxv, 219-202.

PRELIMINARY NOTES ON THE MUTILLIDAE OF MINNESOTA I1l3

MELANDER, A. L.
1903 Notes on North American Mutillidae, with descriptions of new species,
Trans. Amer. Ent. Soc., xxix, 201-330.
RoHwer, S. A.
1909 New Hymenoptera from western United States, Trans. Amer. Ent.
Soc., XXXV, 130-134.
1910 Some new wasps from New Jersey, Proc. Ent. Soc. Wash., xi, 49-50.
1912 Descriptions of new species of wasps in the collections of the U. S.
National Museum, Proc. U. S. Nat. Mus., xli, 455-464.
1916 The Hymenoptera of Connecticut, Mutillidae, Bull. 22, Conn. State
Geolog. and Nat. Hist. Surv., 621-625.
SAve eH,
1823 A description of some new species of Hymenopterous Insects, West.
Quart. Rep., ii, 74. (Leconte Ed., i, 163.)
1836 Descriptions of new species of North American Hymenoptera and
observations on some already described, Boston Jour. Nat. Hist., i,
295-299. (Leconte Ed., ii, 738-741.)
WasHeBurn, F. L.
1918. The Hymenoptera of Minnesota, 17th Rept. State Ent. Minnesota,
208-209, fig. 95-98.

A SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA
By O. W. OESTLUND

A synopsis of the Aphididae of Minnesota was published as
Bulletin No. 4 of the Geological and Natural History Survey of
Minnesota for 1887. This bulletin has long been out of print as well
as out of date. The classification of Thomas, Riley, Monell, and
Buckton, as then usually accepted, was followed. The classification of
the family has undergone great changes since that time, and the author
has long had in mind again to present this early effort of his in a
more modern form. Limit of time and space will not allow a full
account of the various groups and species as now known to occur
in the state, but a key is given that will lead the user to the more
modern name. The practical entomologist and the student have not
the time or the literature at hand to enable them to follow the many
changes that have taken place in the names of many of our genera
and species leading up to a modern phylogenetic view of the family.
The contibutors to this study of the Aphididae for the last thirty
years have been many, for America as well as for Europe and other
parts of the world. Their publications are scattered over a large
number of scientific periodicals and other publications, which only
the specialist may be fortunate enough to possess or to know of.
They are found in various languages, as English, Latin, French, Ger-
man, Italian, Dutch, Scandinavian, and Russian. To codify this exten-
sive and varied knowledge, as far as our fauna is concerned, is one
of the great needs for the present. In a previous contribution by the
author, in which he endeavored to establish the tribes and higher groups
of the family as held somewhat differently by Mordwilko, Van der
Goot, and the author, the statement was made that the groups of tribes,
there recognized and largely suggested by Mordwilko, are not super-
tribes but would eventually work out as such. Mordwilko in some
of his latest works, the Fauna of Russia and Aphids of the Grami-
naceae, has so regarded them. To be sure he calls them tribes and
not supertribes, but this is of minor importance, the important thing
is that they represent natural phylogenetic groups which help us to
form a conception of the probable order of development of the famity.
We differ somewhat as to the number and order of these groups,
but it is out of place to discuss this here. The differences as well as
the similarities can best be expressed by a phylogenetic tree that
accompanies this paper. Quite a number of new generic terms have

SYNOPTICAL KEY TO THE APHIDADAE OF MINNESOTA It5

been suggested which may seem to complicate the classification rather
than simplify it, but the taxonomist, as he finds new relationships and
differences, requires terms to express them, be these specific, generic,
or of higher order.

5e-Horgwaphidini 22-Tetraneurini 14.Wacroaiphini 8. Aphidinit
24. Pemphigini 21.Fordini 1Z%.Mioroeiphini T.Hyelopterini
24.-Prooiphilini 20.Scechironeurini 12.Mysini
I
PEWMFHISZA
H E c
SCHIZONEUREA NACROSYPHBA APHIDEA
Epo
19.Vacunitni 11.Drepanociphini] 6.Chaitophorini
18. Anoeciini 19.Calliptecrini 5-Pterocomnini
17.Tereliini 9.Celsaphidini
lv 16. Phyllaphidini
Fpoch
G D e
PRYLLAPFIDEA CALLIPTERSA CHELITOPHIDREA
15.Hinderini 4-Tresini
§.Pterochlorin:
vekulschnint
ITI
Epoch 1. Lachnini
z A
MINDAZEA LACHNEA
1]
Fpoch Penrphizinae Aphidinee
1 Aphididae
Epoch

heey Oh ELE A PHT DARLO RS MEN NB SORA:

1. Superfamily APHIDOIDEA. It is now generally conceded
that Chermes and Aphis represent distinct families, the Chermesidae
and the Aphididae. Together they form the superfamily Aphidoidea
or Aphidodea of Mordwilko. Some would prefer the term Phyllox-
eridae in place of Chermesidae, but there are no good reasons for

116 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

discarding the term Chermes that has been current in literature for

a century or more. An obvious distinguishing character is the ab-

sence of the stigmal vein (radical sector) in the Chemesidae, and the

simple media which appears as a stigmal vein. In the Aphididae the
radial sector appears as a distinct vein and only very exceptionally
is it reduced or wanting ; the media is usually once or twice branched.

In the following key only the family Aphididae is treated. . . . . 2.

2. Family APHIDIDAE. Tarsi 2-jointed; antennae usually
6-jointed, the terminal segment with a slender prolongation or spur ;
wings transparent and with characteristic aphidian venation. Ab-
domen with a pair of dorsal tubes, or cornicles, on the posterior end,
sometimes very short or wanting; the last segment of the abdomen
with a more or less obvious dorsal projection, the cauda, and usually
with a less obvious ventral projection, the anal plate. Passerini
divides the family into several subfamilies, but the best writers of the
present admit only two:

a. Living exposed on plants. Typical Aphididze in which the antennae, cor-
nicles, and cauda show a tendency to increase in size and complexity ;
sensoria, on ‘the antennae usually circulars. i...) se 5! WEISMAN a

b. Living concealed under woody secretions, in folded leaves, in galls, or
underground on roots; antennae, cornicles, and cauda show a tendency
to become reduced or lost; sensoria on antennae usually transverse or
ATTA ARE, “Aye Aho ee aniegs exe ee RES a a Ee oe PEMPHIGINAE 106

3. Subfamily APHIDINAE. Antennae always longer than the
head and thorax, usually half as long, equal to, or longer than the
body; spur of the terminal antennal segment much longer than the
basal part, sometimes equal to it or shorter in the more generalized
forms. Cornicles obvious as cylindrical tubes; cauda usually well
developed. The fifteen or more tribes of the subfamily may be
grouped in three series of tribes:

a. Spur short; body end appendages thickly covered with long spreading
hairs; found on trunk and limbs of woody plants.....................

Bi creative me owe Series LACHNEA PROPER 4
b. Spur long; hairs on the antennae usually short and spinelike; found on
leaves of trees, on tender growing twigs, or om herbs...............7-5

ies aoe Series LACHNEA-APHIDEA 19
ce. Spur long; hairs on the antennee and usually on the body with enlarged
apices or globate (capitate) ; feeding on leaves of trees or on herba-
CEOUSMP ANUS imine etc oe. eee Series LACHNEA-MACROSIPHEA 62
4. Series LACHNEA PROPER. Antennae about half, the length
of the body; terminal segment with a very short spur (unguis) ; body
and appendages thickly covered with long, slender hairs and sensilla;

SYNOPTICAL KEY TO THE APHIDADAE OF MINNESOTA IIl7

cornicles very short, situated on hairy, cone-shaped tubercles; cauda

short and broad, hardly extending beyond the anal plate. Large,

spiderlike, dark colored forms living in large colonies on woody parts
of trees, or underground on roots or in nests of ants.

a. The three or four tribes of the series are further considered as a super-
tiibelwithethessameyucharacters, aS. thepsemes (44-149 eae cori risicekie ale:

3 Supertribe LACHNEA 5

5. Supertribe LACHNEA. The distinguishing characters are the

same as those already given for the series. Two groups of tribes are
recognized :

a. Stigma of fore wings long and narrow, transverse or blunt at distal end;
radial sector arising from the lower distal angle of the stigma and run-
ning as a straight vein to the margin of the wing. Found exclusively
CIM COtihenarvrs soya Nona eset oie Sala nies Group LACHNINA § 6

b. Stigma long and narrow, or short and broad, the distal end truncate or
ending as a point in the margin of the wing; radial sector arising from
the middle of the stigma, or at least some distance back of the end, and
more or less curved. Found on woody parts of deciduous trees and
MOO CV Dlctitis e Oia a Oml GOOLSIar ay ciocicieieis cisielteld-ieleuee Group TRAMINA 13

6. Group LACHNINA.~ Usually very large forms and in the
aptera spiderlike in appearance and in movements; black or brown
and hairy; rostrum with five distinct segments; media is faint, in-
distinct vein in comparison with the other veins, and is usually twice
branched. Two tribes are recognized in this group:

a. Large forms with wide and globete abdomen and long legs. Found on
PUMkeanadeiimps Ob WCOMtehas sess sieiele vere cere cieasi cele Tribe LACHNINI

b. Medium to small forms with narrow, elongated abdomen; found on the
needles of pines and usually with some green colors..................

Tribe EULACHNINI to

7. Tribe LACHNINI. Large, hairy, black or brown, often with
metallic reflections; legs long, especially the hind pair; found ex-
clusively on woody parts of conifers. Two genera are recognized:

NI

a. The media of the fore wings twice branched.......... Genus LACHNUS 8
b. The media of the fore wings with only one branch..................--
Genus SCHIZOLACHNUS- g
8. Genus LACHNUS (llliger) Burmeister, 1835. Type: Aphis
pini Linnaeus, 1758. Antennae about half the body in length; usually
6-jointed, and terminal segment with a very short spur (unguis).
Size large, body and appendages provided with numerous, long,
spreading hairs; rostrum distinctly 5-jointed. Wings long and _ nar-
row ; stigma long and narrow with distal end blunt or truncate; radial
sector arising from the lower distal angle of the stigma and running

118 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

as a short, straight vein to the margin of the wing; media faint, in-
distinct vein in comparison with the other veins, and usually twice
branched ; hind wings with two oblique veins arising nearer the base
of the wing than usual in the family. Cornicles very short, on hairy,
cone-shaped tubercles; cauda short and broad, extending but slightly
or not at all beyond the rounded anal plate. Found on woody parts
of conifers. The species found in Minnesota may be arranged in
three habitat groups:

a. Abies-Picea group. Very large forms, black or brown, with long oval
abdomen. Basal part of terminal antennal segment with at least 10
sensilla besides the 7 or 8 terminal rods.

(1) LACHNUS CURVIPES Patch, 1912
Found on Balsam Fir, Abies balsamia.

(2) LACHNUS PICEAE (Panzer) Altum, 1875

Found on Spruce, Picea canadensis.

b. Pinus group. Medium large to large, with broad oval or globate abdomen ;
brown and often mottled with darker spots or with metallic reflections.
Basal part of terminal antennal segment with 10 or less hairs besides
the terminal rods.

(3) LACHNUS STROBI (Fitch) Fitch, 1858

Found on White pine, Pinus strobus.
(4) LACHNUS PINI (Linnaeus) Burmeister, 1835

Found on Scotch pine, Pinus sylvestris.
ce. Larix-Juniper group. Medium to small, light brown to yellowish; spur
somewhat longer, basal part of terminal segment with 5 or 6 hairs be-
sides the terminal rods.

(5) LACHNUS LARICIFEX (Fitch) 1858

Found on Tamarack, Larix laricina.

(6) LACHNUS JUNIPERI (DeGeer) Kaltenbach, 1843

Found on Juniper, Juniperus communis,

9g. Genus SCHIZOLACHNUS Mordwilko, 1908. Type: Aphis
tomentosa DeGeer, 1773. Similar to Lachnus but with the media of
the fore wings with only one branch; found on young twigs and
needles of pines.

(7) SCHIZOLACHNUS TOMENTOSUS (DeGeer) Mordwiko, 1908

This widely distributed species has not been taken in the state,
but seen from the West and is reported from various places, and
should be found in Minnesota.

10. Tribe KULACHNINI. The Eulachnini are closely related to
the preceding tribe (Lachnini), but may be distinguished readily by

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 119

their smaller size and elongated body; they are found on the needles
of pines and not on the bark, and usually with some green or paler
colors. They are of much interest as showing the probable line of
modifications leading to the two higher series of tribes of the sub-
family. Several genera are already recognized in the tribe, of which
we have one and probably a second:
a. Antennae 6-jointed; media of fore wings simple, not branched..........
Genus UNILACHNUS 11
b. Antennae 5-jointed; media with one branch......... Genus ESSIGELLA 12
11. Genus UNILACHNUS Wilson, 1919. Type: Lachnus parvus
Wilson, 1915. Size small; antennae 6-jointed; media simple; found
on needles of pines. Only one species is known:

(8) UNILACHNUS PARVUS (Wilson) Wilson, 1919
This species, the smallest known of the Lachnina, has been taken
on the needles of White pine in Minnesota.

12. Genus ESSIGELLA Del Guercio, 1909. Type: Lachnus cali-
fornicus Essig, 1909. Antennae 5-jointed; media of fore wings with
one branch. Found on needles of pines; colors green or yellowish-
green. A genus with only one species known. This may be found
in Minnesota as it 1s reported from both east and west of us.

(—) ESSIGELLA CALIFORNICUS (Essig) Del Guercio, 1909

13. Group TRAMINA. The group is readily separated. from the
Lachnina by the radial sector arising, not from the distal end of the
stigma, but from the middle or some distance back of the tip of the
stigma and running as a more or less curved vein to the margin of the
wing. None are found on conifers but on woody parts of deciduous
trees and other woody plants; some are to be found on roots and
underground in-nests of ants. While the group contains some of the
largest forms known in the family, it also has several medium or
smaller sized forms. Two tribes are recognized:

a. Feeding on woody parts of trees; tarsal joints as usual in the family....
Tribe PTEROCHLORINI 14

b. Feeding underground on roots, or found in nests of ants; tarsi of hind
legs very long, nearly as long as the tibia.......... Tribe TRAMINI 18
Me ibe- LE ROCHLORINIG (Size usually. large +.stigma: of
fore wings long and narrow, sometimes short and broad as usual
in the family; radial sector arising from the middle of the stigma,
or at least some distance back of the apex, and running as a more or
less curved vein to the margin of the wing. While the stigma may
be truncate as in the Lachnini, it is more often rounded and ends

120 NINETEENTH REPORT STATE ENTOMOLOGIST OF MIN NESOTA—I9Q22

as a point in the margin of the wing; media slender but usually more
distinct than in the Lachnini; colors of the body brown or black and
wings often with smoky bands or spots. Found on woody parts of
trees and other woody plants. The tribe is represented by the fol-
lowing genera in Minnesota:
a. Stigma elongate, extending far in the stigmel celi and truncate at the
distal end!; no abdominal dorsal tubercle present. ...2% 42.67. oo oeuer
Genus LONGISTIGMA 15
b. Stigma elongate, pointed distally ; radial sector long end curved only basal-
ly; abdomen with a median dorsal tubercle or gland..................
Genus TUBEROLACHNUS 16
c. Stigma short: radial sector strongly curved; wings usually with dusky
DALCHES hs, cans | aysierd BERR ee beso PA ro PAIN Genus PTEROCHLORUS 17
15. Genus LONGISTIGMA Wilson, 1909. Type: Aphis caryae
Harris, 1841. Stigmal vein arising some distance back of the apex
of the very long and narrow stigma and only slightly curved near
its base, running almost as a straight vein; stigma truncate at apex
in the middle of the stigmal cell, and continued as a dusky band to
or beyond tip of stigmal vein; found on woody parts, as trunks and
limbs, of oak, hickory, basswood, etc. One species is known from
Minnesota :

(9) LONGISTIGMA CARYAE (Harris) Wilson, 1909
This very characteristic species is rather abundant in Minnesota.
The primary habitat is oak rather than hickory. It has repeatedly
been taken on Tilia, hickory and other trees, but the sexes are
known only from the oak. The species was well described by
Monell under the name Lachnus longistigma taken on Tilia.

16. Genus TUBEROLACHNUS Mordwilko, 1908. Type: Aphis
viminalis Boyer, 1841. Stigma long, apically rounded and ending
in the margin of the wing. Abdomen with a dorsal median tubercle,
which is apparently glandular in function. Found in large colonies
on woody parts of willow. One species is known from Minnesota :

(10) TUBEROLACHNUS VIMINALIS (Boyer) Mordwilko, 1908
Found on various willows, Salix.

17. Genus PIEROCHLORUS Rondani, 1848. Type: dphis ro-
boris Linnaeus, 1758. Stigma short, apically rounded; stigmal vein
strongly curved; wings usually with spots. Found on woody parts
of oak and rose. One species is known from Minnesota:

~ (11) PTEROCHLORUS ROSAE (Cholodkovsky)

Found on the stalks of the rose, usually close to the ground or
even partly under ground.

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 121

18. Tribe TRAMINI. Distinguished by the very long tarsal joint
of the hind legs. [Found on roots of plants and in nests of ants. No
representative of this tribe has been recorded from Minnesota, but
probably occurs. They must be looked for on roots of plants (trees
‘and Compositae) and also in nests of ants.

19. Series LACHNEA-APHIDEA. Antennae 6-jointed, rarely
only 5-jointed; spur of terminal segment as long as or longer than
the basal part; sensilla of the antennae hair-like or spinelike ; cornicles
short and truncate, or long and cylindrical; cauda usually obvious
and projecting beyond the rounded anal plate. The series includes
two supertribes :

a. Antennae usually shorter than the body, with numerous long, curved
hairs like those in Lachnus; spur usually much longer than the basal
part; cornicles short and of the truncated type, not longer than broad,
Omuimlonger then swollens.a.). .ct.ccs + te Supertribe CHAITOPHOREA 20

b. Antennae usually as long 2s or longer than the body; sensilla on the
antennae usually short and spinelike with a pointed apex; cornicles cylin-
dricel and much longer than broad, sometimes very short and small or
SATO ee tegen ery AU an cfm rayne tree ere Nee natin clererteae 7c a Supertribe APHIDEA 29
20. Supertribe CHAITOPHOREA. The long, spreading, curved

hairs of the body and appendages are characteristic of the Chaito-
phorea. While some are still found on the bark and woody parts of
trees, most of them have become adapted to live on the leaves and
succulent growth of their host plant. There is an obvious and easy
transition fom the Lachnea to the Chaitophorea. Two tribes are
represented in Minnesota:

a. Usually large forms found on woody parts of treés; cornicles longer
then broad and swollen, rarely cylindrical, and usually pale, yellow or
red, contrasting with the darker colors of the body...................

Tribe PTEROCOMMINI a1

b. In size medium to very smell and depressed forms found on leaves and
succulent growths of trees, rarely on the woody parts; cornicles short
and truncate, rarely absent; cauda triangular, extending beyond the
Anlaleen Ate ser OsStnuil esos miss eter Tribe CHAITOPHORINI 25

/

21. Tribe PTEROCOMMINI. The Pterocommini represent the
generalized Chaitophorea which stand nearest to the Lachnea as seen
in their large size, shorter antennae, and moderately long spur in
comparison with the more highly specialized Chaitophorini; they are
all bark feeders on woody plants. Characters in advance over the
Lachnea are their shorter legs, enlarged cornicles. The lateral
tubercles of the body are also better preserved than in the Lachnea.
Representatives of three genera are known from Minnesota:

122 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

a. Corhicles*cylindrical, pale-) habitat Ropulsesn(Sai) eee a ct eee
Genus PTEROCOMMA 22
b. Cornicles more or less distinctly swollen; in color pale yellow or red;
habitat sS alata (Populus) eciasccs centre Genus MELANOXANTHERIUM 23
c. Cornicles slightly swollen and abruptly constricted at distal end with a
very small opening; body covered with flocculent matter as in the Pem-
phiginae:,habitabes Glenna eens ee eee Genus PLOCAMAPHIS 24
22. Genus PTEROCOMMA Buckton, 1879. Type: Pterocomma
pilosa Buckton, 1879. Cornicles cylindrical. No representative of
this genus is known from Minnesota but is likely to be found.

23. Genus MELANOXANTHERIUM (Koch) Schouteden, root.
Type: Aphis salicis Linnaeus, 1758. Size large; cornicles pale, yellow
or red and distinctly swollen. The following species are known from
Minnesota :

(12) MELANOXANTHERIUM SALICIS (Linnaeus) Schouteden,
IQOI

Color bluish black with white patches of pulverulent matter on

the abdomen; spur of the terminal segment of the antennae

shorter than the cornicles; veins of the wings with dusky bor-

ders, anal vein especially conspicuous in this respect. Rather com-
mon on branches of willow.

(13) MELANOXANTHERIUM BICOLOR (Oestlund)

Color reddish brown, the pulverulent spots less conspicuous; spur
of the terminal antennal segment about equal to the cornicles and
twice as long as the basal part; veins clear without dusky bor-
ders. Much rarer species, sometimes found in small colonies with
the above form.

(14) MELANOXANTHERIUM SMITHIAE (Monell)

Color dark brown; terminal segment of the antennae longer than
the cornicles; cornicles short, not more than twice as long as
broad.

24. Genus PLOCQAMAPHIS gen. nov. Type: Melanoxanthus
flocculosus Weed, 1891. Color dull yellowish brown; body very floc-
culent; cornicles longer than broad, swollen above the middle and
strongly contracted to a very small opening without a flange. The
very distinct type of cornicles with the conspicuous flocculent matter
would indicate distinct generic differences. One species is recorded:

(15) PLOCAMAPHIS FLOCCULOSUS (Weed)

This peculiar form is not rare on willow

25. Tribe CHAITOPHORINI. The Chaitophorini are medium
to small in size in comparison with the preceding tribe, the body is
more or less depressed, with shorter legs and rostrum; antennae about

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 123

as long as the body, and the spur of the terminal segment longer than.

the basal part; cornicles short and truncate, not longer than wide,
cauda short and broad, triangular or globate, projecting beyond the
rounded anal plate. The following genera are represented in Min-
nesota:

a. Cauda short and broad, like the Pterocommini; veins with dusky borders ;

found- on Populus. ...c.cccceseceieses Genus NEOTHOMASIA 26
b. Cauda triangular; with dimorphic summer forms; found on maple and

OE CLL CT Pear etches lek ers teal ae Rants EES Genus -RPERIPRYLEUS 27
c. Cauda triangular or globate; no peculiar summer generations present;

found on willow end poplar......... Genus CHAITOPHORUS 28

26. Genus NEOTHOMASIA (Wilson) Baker, 1920. Type:
Chaitophorus populicola Thomas, 1879. Cauda broad; habitat Populus.
The generic characters approach the Pterocommini and represent the
generalized and transitional forms of the Chaitophorini. Only one
species is recorded and rather common in the state:

(16) NEOTHOMASIA POPULICOLA (Thomas) Baker, 1920

Common on cottonwood.

27. Genus PERIPHYLLUS (Thornton) Van der Hoven, 1863.
Type: Phyllophorus testudinatus Thornton, 1852. The genus is well
characterized by the presence of summer generations that are very
different from the ordinary spring and fall forms; the dimorphs are
very small and greatly depressed, with fanlike setae around the margin
of the body, and show no disposition to grow or change for a month
or more. The habitat of the genus is maple and box elder.

(17) PERIPHYLLUS NEGUNDINIS (Thomas) Baker, 1920
Rather common and sometimes injurious to box elder.

28. Genus CHAITOPHORUS Koch, 1854. Type: Aphis popula
Linnaeus, 1758. Cauda usually enlarged at apex or globate. The
dimorphic summer forms are never present. The habitat of the
genus is willow, poplar, and oak. Several species are known from
the state, but the species are difficult to separate and have not been
sufficiently studied:

me) CHAITOPHORUS VIMINALIS Monell, 1879
Surface of the head with broken reticulations or granulations;
spur long; color yellowish green.

(19) CHAITOPHORUS NIGRAE Oestlund, 1886

Surface of the head with distinct reticulations, not broken; colors
green or black.

124 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

(20) CHAITOPHORUS DELICATA Patch, 1913
Color pale with transverse bands on the abdomen; larvae whit-
ish; this small and delicate little species is found on Populus den-
tatus and willow.

(21) CHAITOPHORUS QUERCICOLA Monell, 1879
Veins of wings with dusky bends; larvae with stout brown or
black spines; found on the leaves of oak.

29. Supertribe APHIDEA. Abdomen short and broad and
abruptly rounded posteriorly, rarely elongated; antennae usually as
long as or longer than the body with spur much longer than the basal
part; sensilla usually short and spinelike; cornicles rather stout and
much longer than broad, sometimes distinctly swollen in the middle,
or again very small and inconspicuous; cauda distinct and usually
triangular with a clear area near the base. Migration from winter
habitat, usually some tree, to more succulent herbs for the summer
and again returning to the winter habitat for ovipositing is rather
common in the group. Two tribes are represented:

a. Cornicles very short and small, usually shorter than the cauda.........
Tribe. HYALOPTERIND 3a
b. Cornicles longer than the cauda (with some exceptions) and cylindrical

or swollen; body short and legs moderately long....Tribe APHIDINI 34

30. Tribe HYALOPTERINI.. The, Hyalopterini -are “quite wa
large assemblage of genera, which should be held distinct from the
Aphidini proper, as representing a more primitive line of develop-
ment in which the cornicles are very short and weak (not reduced).
The body 1s more or less elongated and pulverulent ; antennae shorter
than the body; rostrum and legs short. Three genera are present in
Minnesota :

a. Living exposed or in crumpled leaves; migrating from plum to Phrag-

ABVUBG Sri sea cg eee ane = Rey nt Ry Genus HYALOPTERUS 31
b. Living in closely folded, pod-like leaves on Chenopodium albus..........

Genus HAYHURSTIA 32
c. Living exposed on cruciferous plants and on cabbage; cornicles slightly

swollen” 253 0...e sea sum oon eR Pee Genus BREVICORYNE 33

31..Genus HYALOPTERUS Koch, 1854. Type: Aphis prunt
Fabricius, 1775. Secondary sensoria in migrant scattered and present
on the third and fourth segments; cornicles short and slender, slightly
narrower basally.

(22) HYALOPTERUS PRUNI (Fabricius) Koch, 1854
Found on plum and during the summer on Phragmuites.

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 125

32. Genus HAYHURSTIA Del Guercio, 1909. Type: Aphis
atriplicis Linnaeus, 1761. Secondary sensoria in migrant in a row on
the third segment of the antennae; cauda rather long and slender.

(23) HAYHURSTIA ATRIPLICIS (Linnaeus) Del Guercio, 1909
Found in podlike folds of the leaves on Chenopodium.

33. Genus BREVICORYNE Van der Goot, 1915. Type: Aphis
brassicae Linnaeus, 1758. Cornicles slightly swollen in the middle
and short ; secondary sensoria in migrant, numerous and scattered on
the third segment of the antennae.

(24) BREVICORYNE BRASSICAE (Linnaeus) Van der Goot, 1915
Found on cruciferous plants and on cabbage.

34. Tribe APHIDINI. The Aphidini have the body usually short
and rounded posteriorly ; antennae usually about as long as the body,
with spinelike sensilla, which rarely are long and hairlike; cornicles
cylindrical or swollen, stout and often wider at base and tapering ;
reticulations on cornicles in broken lines; cauda obvious, triangular,
and usually with a clear area at base. Found on leaves of trees or
more commonly on herbs. This is the largest tribe in the family,
rich in genera and species. Two main divisions may be recognized :

a, Commoles- ey hinchacei ll Jac docuucpcsueodoc Division CYLINDRICORNIA 35
MB GGERGLES * SWONMENIS, «ro. os. ulate: oreid o Ors Sa teheyeha'v os Division CLAVICORNIA 55

35. Division CYLINDRICORNIA. Cornicles stout, cylindrical,
usually much longer than the cauda; reticulations on the cornicles
broken or disconnected lines. The genera of this large division may
further be divided into three groups:

a. Antennae provided with long, slender hairs like those found in the
Ghaitophoncar swe eae horse ee The CHAITOPHOROIDES group 36

b. Sensilla on the antennae short, str2ight and spinelike hairs...............
The APHIS group 4o

c. Similar to the preceding group but showing some marked aberrant cher-

acter as reduced venation or antennal segments, tarsal characters,

SCO ici ERR ay REUSE hg ee ae ania ay et ee The TOXOPTERA Group
36. The CHAITOPHOROIDES group. Mordwilko separated a

rather large aphis form with the body and appendages provided with

I

On

long, slender hairs like those of the Chaitophorea under the generic
name Chaitophoroides. We have several similar forms in America,
not all of which can be placed in Mordwilko’s genus. Three genera
of the group are at present known from Minnesota:

a. Secondary sensoria in migrant 15-30, rather large; pulverulent glands,
when present, in dorsal longitudinal rows; cornicles cylindrical.......
.Genus CHAITOPHOROIDES 37

126 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

b. Secondary sensoria in migrant 50 or more, small and scattered; pulverutent
glands massed in large areas on each side of the abdomen; cornicles

cylindrical and -Aphis-likeses. 2... ae Genus AMPHICERCIDUS 38
c. Secondary sensoria in migrant 40 or more, smail and scattered; pulveru-

lent glands along the sides of the ebdomen; cornicles very short, not

longer -thanswides tava cotetra keratoses wearers Genus GYPSOAPHIS 39

37. Genus CHAITOPHOROIDES Mordwilko, 1908. Type: Apis
lantanae Koch, 1854. Size large with the aspect of a Pterocommiuni;
antennae with long, slender hairs ; cornicles rather long and cylindrical ;
cauda triangular and Aphis-like with many scattered hairs. Found
on tender twigs and leaves of various trees and woody plants. The
following species are recorded from Minnesota:

(25) CHAITOPHOROIDES MACULATA (Oestlund)

Found on Cornus and Populus and sometimes on Salix.

(26) A second species found on elm is imperfectly known and unde-
scribed. Forms of this genus have in the past been more or less
mixed with the Pterocommini, and will require an extended syn-
onymical study to clear un,

38. Genus AMPHICERCIDUS gen. nov. Type: Apis pulveru-
lens Gillette, 1911. Third joint of the antennae rather long and pro-
vided with numerous small sensoria (50 or more) in migrant;
body strongly pulverulent, the glands massed along the sides of the
abdomen. Found on the stem of wolfberry, close to the ground. The
sexes appear late in September. One species is known:

(27) AMPHICERCIDUS PULVERULENS (Gillette)

Brownish; strongly pulverulent; on the stems of Symphoricarpus
occidentalis.

39. Genus GYPSOAPHIS gen. nov. Type: Aphis lonicerae
Monell, 1879. The third joint of the antennae in migrant long and pro-
vided with many small sensoria; cornicles short, not longer than broad ;
body strongly pulverulent. Found on stalks and leaves of Lonicera
glauca. One species is known:

(28) GYPSOAPHIS LONICERAE (Monell)

A large green form found on honeysuckle.

40. The APHIS group. Abdomen broad and short, segments 6-8
usually abruptly narrowed; cornicles cylindrical, or wider at base;
reticulation on cornicles broken; sensilla of antennae short and spine-
like; cauda short and triangular, or rather long, cylindrical, and
pointed, with hairs showing tendency to be arranged in rows; spur of
antennae always longer than the base; rostrum moderately long and

a

Se

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 127

stout ; lateral tubercles usually present. Found on trees, or migrating
to herbs for the summer, or their entire history is passed on herbs.
Four genera are found in Minnesota, two of which must be indicated

mas LEW ;

a. Pleurites on the sides of the body with large glands in place of lateral
tubercles. The secondary sensoria of the antennae with.wide margins,
and crowded so as to be transversely oval; cauda short................

Genus CEDOAPHIS 41

b. Pleurites with lateral tubercles in place of glands; secondary sensoria with
wide margins but not crowded so as to be transversely oval; cauda
Aphis-like; cornicle narrower at base........... Genus THARGELIA 42

c. Pleurites with lateral tubercles in place of glands; secondary sensoria
with narrow border, circular; cornicles short, with spinelike crowded
reticulations; cauda short and triangular........ Genus ANURAPHIS 43

d. Pleurites with leteral tubercles, sometimes reduced or wanting; secondary
sensoria with narrow border and circular; cornicles usually long and
cylindrical, with open, loose reticuletions; cauda rather long, cone-
Sushil ere eoyahea harceill Bhs a wale nen BS cleo cioiec cbc ese corte cio Genus APHIS 44

41. Genus CEDOAPHIS gen. nov. Type: Aphis symphoricarpi

Thomas, 1878. The pleurites on the sides of the body are provided

with very large glands in line with the lateral tubercles and cornicles

when present. These glands are not pulverulent or wax glands, but
of the same order as the cornicles which are also glandular in function.

These glands are apparently very primitive structures and are best

S I ; Y.-J

seen in the present genus, and again in some of the more generalized

Callipterini. Their association with the lateral tubercles and cornicles

opens up a very interesting field in connection with the functions and

origin of the cornicles so unique and characteristic of the family

Aphididae.
(29) CEDOAPHIS SYMPHORICARPI (Thomas)

Found in distorted leaves of Symphoricarpus.

42. Genus THARGELIA gen. nov. Type: Aphis albipes Oestlund,
1887. Pleurites with lateral tubercles in place of glands; cornicles
narrowed at base and slightly swollen toward the apex; secondary
sensoria on the antennae with wide margins, but smaller than in the
preceding genus and not crowded. The secondary sensoria of these
two genera indicate a distinct form from those found in the rest of
the family.

(30) THARGELIA ALBIPES (Oestlund) —

Found on Symphoricarpus in twisted leaves, sometimes on the
same bush with the much rarer form Cedoaphis symphoricarpi.

128 NINETEENTH REPORT STATE~- ENTOMOLOGIST OF MINNESOTA—IQ22

43. Genus ANURAPHIS Del Guercio, 1907.. Type: Aphis pyre
Koch, 1854. Pleurites with lateral tubercles in place of glands; sec-
ondary sensoria of antennae with narrow margins, and of the usual
type; cornicles short, cylindrical, with crowded reticulations, which
appear as rows of minute spines; cauda short and cone-shaped. The
genus as first indicated by Del Guercio, based on the relative length
of the cornicles and cauda, is an artificial character and will not hold.
Baker has lately restricted the genus, based on the peculiar type of
cauda. Tho better, it also is not sufficient to separate it from the
genus Aphis. Adding to this the peculiar type of reticulations on the
cornicles, we probably have a natural genus. Two species are known
from Minnesota:

(31) ANURAPHIS BAKERI (Cowen) Baker, 1920
The short-beaked clover aphis. Found on apple end clover.
(32) ANURAPHIS CRATAEGIFOLIAE (Fitch) Baker, 1920
The long-beaked clover aphis. On Crataegus and clover.

44. Genus APHIS Linnaeus, 1758. Type: Aphis sambuci Linnaeus,
1758. Pleurites with lateral tubercles (sometimes reduced in number
or wanting) ; cornicles long and cylindrical (sometimes reduced or want-
ing), cr with a wider base; reticulations on the cornicles open or
broken lines; cauda usually long and more or less copstricted near
the base, and usually with a clear area above. Several attempts have
been made of late to further restrict the genus but without satisfactory
results. The grouping of the species is still unsatisfactory and more
or less artificial, but is probably the best that can at present be given
with the incomplete knowledge of their life histories and the sexes.
The species may be grouped in two divisions based on the arrangement
of the secondary sensoria on the antennae:

a. The secondary sensoria on the antennae are numerous (15-50 or more),
scattered, circular, and ‘varying more*sor less in Sizey..7 -.0- -qen ee

Division POLYSENSORIA 45
b. The secondary sensoria on the entennae are found in small numbers (4-15),
usually large and subequal, and arranged in a single row, or nearly so..

Division PARVISENSORIA 48

45. Division POLYSENSORIA. The Polysensoria probably rep-
resent an early condition of the secondary sensoria, when they were
numerous, small, and scattered over the first three segments of the
flagellum. With their further development for greater efficiency, they
became fewer and larger, allowing more favorable positions for func-
tioning, which gave rise to the second division as the more modern

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 129

and specialized. The division may further be divided into two sections
based on the number of segments with secondary sensoria :
a. The third segment of the antennae with 12 or more sensoria; the fourth
and usually also the fifth with a smaller number............ Section A 46
b. Secondary sensoria present only on the third segment.......... Section B 47
46. Section A. The third segment of the antennae with 12 or
more sensoria more or less scattered; the fourth and usually the fifth
with a smaller number. Usually rather large forms. The following
species are recorded from Minnesota:
(33) APHIS HELIANTHI Monell, 1879

Found on Helianthus; dark green in color; when numerous cause |
the leaves to curl.

(34) APHIS MIDDLETONI Thomas, 1878

Found on the roots of Erigeron canadensis and other Compositae.
(35) APHIS THASPII Oestlund, 1887

Found on Thaspium aurewm; abdomen dark green.
(36) APHIS NEILLIAE Oéestlund, 1887

Found on Ninebark, Physocarpus opulifolius; abdomen black.
(37) “APHIS -CARDUELLA > Walsh, 1862

Found on Circium; abdomen dull green.
(38) APHIS NEPETAE Kaltenbach, 1843

Found on Nepeta catarea; abdomen green.
(39) APHIS RUMICIS Linnaeus, 1758

Found on Rumex, Chenopodium, and other herbs; abdomen black.
(40) APHIS MAIDIS Fitch, 1856

Found on corn; abdomen green.
(41) APHIS MIMULI Oestlund, 1887

Found on Mimulus: a very small form; abdomen pale green.

47. Section B. Secondary sensoria are found only on the third
segment. The following species are known from Minnesota :

(42) APHIS CARDUI Linnaeus, 1758

Found on plum and thistle; rostrum very long for an Aphis.
(43) APHIS RIPARIAE Oestlund, 1886

Found on Vitis riparia,
(44) APHIS CORNIFOLIAE Fitch, 1851

Found on Cornus; abdomen dark brown.
(45) APHIS OXYBAPHI Oestlund, 1887

Found on Oxybaphus angustifolia.

130 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I1Q22

(46) APHIS ASCLEPIADIS Fitch, 1851
Found on Asclepias cornutus and related plants.

48. Division PARVISENSORIA. Secondary sensoria are usually
large, equal in size, and fewer in number (4-12), arranged in a single
row, or nearly so. This division may also be considered under two
sections based on the position of the sensoria on certain segments:

a: -Sensoria, present ion, Sezments:37to) 5... asces. ce oui alent nase es Section A 49
b: Sensoria: restricted to. the third ssesmientij.. «iis rte areas ees Section B 50

49. Section A. Sensoria or segments 3 and 4 or 3 to 5. The fol-
lowing species occur in Minnesota:
(47) APHIS LUTESCENS Monell, 1879
Found on Asclepias syriaca.
(48) APHIS SPIRAEAE Oestlund, 1887
Found on Spiraea salicifolia.
(49) APHIS IMPATIENTIS Thomas, 1878
Found on Impatiens fulva.
(50) APHIS MONARDAE Oestlund, 1887
Found on Manarda fistulosa.
(51) APHIS FRONDOSAE Oestlund, 1886
Found on Bidens frondosa.
(52) APHIS EUPATORIL Oestlund, 1886
Found on Eupatorium perfoliatwm.
50. Section B. Sensoria restricted to the third segment.
(53) APHIS POMI DeGeer, 1773
Found on apple and Graminaceae.

(54) APHIS SALICICOLA (Thomas) Monell, 1879
Found on the leaves of willow.

(55) APHIS CERASIFOLIAE Fitch, 1855
Found on chokecherry, Prunus virginiana.

(56) APHIS FORBESI Weed, 1889
Found on strawberry.

(57) APHIS RUBICOLA Oéestlund, 1887
Found on leaves of Rubus.

(58) APHIS APARINES Fabricius, 1775
Found on Galium aparine, twisting the leaves.

(59) APHIS OENOTHERAE Oeéestlund, 1887
Found on Oenothera.

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA I3I

51. Group TOXOPTERA. In a more strict classification the fol-
lowing genera would be arranged with the preceding group, but it is
more practical to consider those genera separately that differ greatly
in some one character which at once distinguishes them from the
ordinary Aphis. Such aberrant characters are a reduction in venation,
- antennae, or tarsi. The following genera are known from Minnesota:

a. Media of forewings with only one branch........ Genus TOXOPTERA 52
b. Hind wings with only one oblique vein....... Genus HYSTERONEURA 53

ce. Tarsi of all the legs reduced and without claws..Genus MASTOPODA 54
52. Genus TOXOPTERA Koch, 1857. Type: Aphis aurantiae
Boyer, 1841. Media with only one branch in the fore wings; cornicles
cylindrical and moderately long; cauda Aphis-like; sensoria on the
antennae in small*number.
(60) TOXOPTERA GRAMINUM (Rondani) Passerini, 1860
This southern grain aphis is at times quite common.

53. Genus HYSTERONEURA Davis, 1919. Type: Siphonophora
setariae Thomas, 1878. Aphis-like in characters, but the hind wings
have but one oblique vein; sensoria on the antennae in small number. |

(61) HYSTERONEURA SETARIAE (Thomas) Davis, 1919
This red-brown species is rather common on plum, migrating to
various grasses for the summer.

54. Genus MASTOPODA Oestlund, 1886. Type: Mastopoda
pteridis Oestlund, 1886. Antennae with only five segments, the third
and fourth connate; cauda short and cone-like; tarsi reduced to a
small mamma-like joint without claws. Found on fern.

(62) MASTOPODA PTERIDIS Oestlund, 1886
Found on Pteris aquilina; a comparatively rare form.

55. Division CLAVICORNIA. Koch placed all aphids with
swollen cornicles in the genus Rhopalosiphum; it has since been found
that swollen cornicles are present in many of the tribes of the family
and that the character is more than generic. Koch’s Rhopalosiphum
has therefore been broken up into numerous genera, some of which
belong to the division Clavicornia of the tribe Aphidini. The division
‘includes those genera that are Aphis-like, but with distinct swollen
cornicles. The following genera are found in Minnesota:

a. Cornicles swollen on the apical half; cauda slender... .............5-000-
Genus RHOPALOSIPHUM 56

b. Cornicles slightly swollen in the middle; cauda stout.................-06-
Genus SIPHOCORYNE 57

c. Cornicles strongly swollen in the middle.......... Genus LIOSOMAPHIS 58

>

132 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

d. Abdomen with a dorsal tubercle above the cauda...Genus CAVARIELLA 59
e. Cornicles with two swellings, one in the middle and one apical............

Genus CACHRYPHORA 60
f. Cornicles with only the apical swelling......... Genus EPAMEIBAPHIS 61

56. Genus RHOPALOSIPHUM Koch, 1854. Type: Aphis
nymphaeae Linnaeus, 1761. The characters are those of the genus
Aphis, but with the cornicles swollen on the upper. half, or club
shaped.

(63) RHOPALOSIPHUM NYMPHAEAE (Linnaeus) Koch, 1854
A species common on various water plants.

57. Genus SIPHOCORYNE Passerini, 1863. Type: Aphis xylos-
tet Schrank, 1801. Similar to Rhopalosiphum but with a large and
stout cauda.

(64) SIPHOCORYNE XYLOSTEI (Schrank) Passerini, 1863
Found on honeysuckle (Lonicera).

58. Genus LIOSOMAPHIS Walker, 1868. Type: Aphis ber-
beridis Kaltenbach, 1843. Cornicles distinctly swollen in the middle,

(65) LIOSOMAPHIS BERBERIDIS (Kaltenbach) Walker, 1868
At times abundant on barberry.

59.: Genus CAVARIELLA Del Guercio, 1911. Type: Aphis pas-
tinacae Linnaeus, 1758. The distinguishing character of this genus
is the presence of a tubercle above the cauda, which appears as a
cauda above the cauda.

(66) CAVARIELLA PASTINACAE (Linnaeus) Del Guercio, 1911
Found on parsnips and other umbelliferous plants.

(67) CAVARIELLA SALICIS (Monell)
Rather common on Salix.

60. Genus CACHRYPHORA gen. nov. Type: Rhopalosiphum
serotinae Oestlund, 1887. Cornicles with a double swelling, one in
the middle and a second as a distinct swelling of the apex, a decided
constriction separates the two; cauda conical. The enlarged apices”
of the sensilla on the head and antennae would indicate a Myzini re-
lationship, but the frontal margin and the head place it in the tribe
under consideration.

(68) CACHRYPHORA SEROTINAE (Oestlund)

Cornicles capitate at apex and swollen below
Found on goldenrod, solidago.

61. Genus EPAMEIBAPHIS gen nov. Type: Aphis frigidae
Oestlund, 1886. We may also include this genus with the Clavicornia

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 133

based on the swollen, knob-like apex of the cornicles, tho the sensilla
show Macrosiphea characters.

(69) EPAMEIBAPHIS FRIGIDAE (Oestiund)
Found on Artemisia frigida.

62. Series LACHNEA=-MACROSIPHEA. Traced from a com-
mon stock with Lachnea and the series Lachnea-Aphidea, we have two
other supertribes that have evolved alongside the Aphidea line.
The body is usually large and pointed posteriorly ; antennae usually
longer than the body, with very long spur, and provided with apically
enlarged sensilla and hairs on the antennae and other parts of the
body. The two supertribes of the series may be separated as follows :
a. The glandular apex of the sensilla globate; cornicles short and truncate...

Supertribe CALLIPTEREA 63
b. The glandular apex of the sensilla flattened and spearlike ; cornicles usually
lonewands cylindiacals ten ao set cree oi Supertribe MACROSIPHEA 83

63. Supertribe CALLIPTEREA. Sensilla on the antennae and
on the body, especially in larval forms, glandular and ending in glob-
ular apices ; cornicles short and truncate, usually not longer than broad ;
cauda usually ending in an enlarged or globate apex. The supertribe
differs from the rest of the family in being sporadic and not gregari-
ous, never found in large colonies, and in the fact that the_partheno-
genetic generations all acquire wings before reproducing. The follow-
ing tribes are represented in Minnesota :

a. Large and Macrosiphum-like, front strongly emargineted................
Tribe CALAPHIDINI 64

b. Medium to small, front not strongly emarginated; cauda globate..........
Tribe CALELIPTERINI- 68

Ge Conmiciess longer tharmproad widest at Das o.i2 (2 a: Laie enw oe aegis aivyallags
Tribe DREPANOSIPHINI 81

64. Tribe CALAPHIDINI. Size large and front strongly emar-
ginated as in the Macrosiphini; cornicles usually somewhat longer than
broad and cylindrical, sometimes swollen at base. Body and appen-
dages often with pulverulence or wax threads. Three genera are
recognized :

a. Spur shorter than the very long base; stigmal vein distinct; cornicles
swollen or bulged at base.. Genus QUIPPELACHNUS 65

b. Spur shorter than the base; stigmal vein distinct; cornicles cylindrical.....
Genus EUCERAPHIS 66

c. Spur longer than the base; stigmal vein indistinct on besal half or more;
cornicles; eylitidrical iec.. veces ehi een =< Genus CALLIPTERINELLA 67

134 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I922

65. Genu QUIPPELACHNUS gen. nov. Type: Euceraphis gil-
lettei Davidson, 1915. Spur of terminal antennal segment shorter than
the base; stigmal vein distinct; cornicles swollen or bulging at base.
Habitat Alnus.

(7o) QUIPPELACHNUS GILLETTEI (Davidson)
A conspicuous western and northern form with tufts of flocculent
strands on body and legs.

66. Genus EUCERAPHIS Walker, 1870. Type: Aphis betulae
Koch. Spur shorter than the base; stigmal vein distinct; cornicles
cylindrical; anal plate usually entire.

(71) EUCERAPHIS BETULAE (Koch)
Sensoria on the third joint, crowded on the enlarged basal part.
Found on Betula.

(72) EUCERAPHIS ALNIFOLIAE (Fitch)
Sensoria not crowded. Found on Alnus.

67. Genus. CALLIPTERINELLA- Van der Goot, 1913.) bype=
Aphis betularius Kaltenbach, 1843. Spur of the antennae longer than
the base; stigmal vein indistinct on the basal half or more; cornicles
cylindrical.

(73) CALLIPTERINELLA BETULAECOLENS (Fitch)
Rather common on Betula,

68. Tribe CALLIPTERINI. Size moderate to small; cornicles
short and truncate; cauda globate at apex; antennae with the spur
shorter or much longer than the base. This large and interesting
tribe has long been a favorite with aphidologists: Their classification
is still unsatisfactory, but of great phylogenetic value as it gives a
picture of a very remote condition of the family that has become
lost by all the other tribes. The following subtribes are represented in
Minnesota:

a. Found on woody parts of trees (Corticola group)..Subtribe SYMYDOBII 69

b. Found on leaves of walnut and hickory (Juglans-Myrica group)..........
Subtribe PANAPHIDII 71

c. Found on leaves of linden and oak (Tilia-Quercus group)................
Subtribe CALLIPTERII 76

69. Subtribe SYMYDOBII. Corticola group. Antennae about as
long as the body; spur of the terminal segment about equal to the
base; cornicles short and truncate and cauda slightly emarginated ;
abdomen with lateral tubercles and rather hairy; sensilla spine-like.
A genus that stands midway between the Chaitophorea and the Callip-
terea but is usually considered to belong to the latter.
a> With characters “of thepsubtribe..... Ses «ns cmen se Genus SYMYDOBIUS 70

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 135

70. Genus SYMYDOBIUS Mordwilko, 1894. Type: Aphis oblonga
Heyden, 1837. Our American representative of this genus has long
been considered the same as the type form of Europe, but Baker has
lately indicated it as distinct.

(74) SYMYDOBIUS AMERICANUS Baker
Found on shoots and twigs of Betula papyracea.

71. Subtribe PANAPHIDII. Juglans-Myrica group. Antennae
usually much shorter than the body; spur shorter than the base; anal
plate emarginated. Found on walnut and hickory. The following
genera may be indicated :

a. Antennae less than half the length of the body....... Genus PANAPHIS 72
b. Antennae about half the length of the body...... Genus CHROMAPHIS 73
c. Antennae as iong as or longer than the body.......... Genus MONELLIA 74
d. Antennae longer then the body; many spine-like tubercles on various parts
GieGMeRDOUVAN, Sac <cs cess = oor Sites TE Ste Genus MELANOCALLIS 75

72. Genus PANAPHIS Kirkaldy, 1904. Type: Aphis juglandis
(Frisch) Gmelin, 1788. The very short antennae and spur led Pas-
serini to consider juglandis the type of his Callipterus which was
placed with the Lachnini. Koch considered it a Callipterint.

(7s) PANAPHIS JUGLANDIS (Gmelin) Kirkaldy, 1904
On the upper sides of the leaves of walnut. Not known from
Minnesota but may be looked for.

73. Genus CHROMAPHIS Walker, 1870. Type: Lachnus jug-
landicola Kaltenbach, 1843. Antennae about half the length of the
body.

(76) CHROMAPHIS JUGLANDICOLA (Kaltenbach) Walker, 1870
Found on the underside of the leaves of walnut.

74. Genus MONELLIA Oestlund, 1887. Type: Aphis caryella
Fitch, 1855. Antennae longer than the body; spur of the terminal
segment somewhat shorter than the base; cornicles very short, small
and primitive and not far in advance of the lateral tubercle type.
The following species are found here:

(77) MONELLIA CARYELLA (Fitch) Oestlund, 1887
This delicate whitish form is rather common on the leaves of
hickory.

(78) MONELLIA CARYAE (Monell) Gillette, 1910

Found with the ebove species; not as depressed and wings held
roof-like at rest.

136 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

75. Genus MELANOCALLIS gen. nov. (The black beauty):
Type: Callipterus caryaefoliae Davis, 1910. This very interesting form
is found on the leaves of hickory. They are found as minute black
specks along the veins and have considerable leaping ability. The body
is provided with many spinelike tubecles on various parts:

(79) MELANOCALLIS CARYAEFOLIAE (Davis)
Found on the underside of the leaves of Carya.

76. Subtribe CALLIPTERII. (Tilia-Quercus group.) The sub-
tribe indicates the maximum of Callipterini development. The North
American continent seems to be their center of distribution as at-
tested by the large number of species found in comparison with other
parts of the world. The group has a wide habitat on forest trees,
besides Tilia and Quercus they are also found on Alnus, Corylus,
Castania, etc. _The following genera are found in Minnesota:

a. On Tilia. Base of terminal antennal segment elongated..................-
Genus CALLIPTERUS 77
bo (On Alnus.) Base noteloneatedepas acts ene Genus PTEROCALLIS 78

c. On Corylus and Quercus. Stigmal vein often indistinct...................
Genus MYZOCALLIS 79

d: On Quercus end Ulmus. Body with dorsal-tubercles/=3.22....-0.s meio
Genus TUBERCULATUS 8o

77. Genus CALLIPTERUS Koch, 1855. Type: Aphis tiliae Lin-
naeus, 1758. Stigmal vein distinct; base of terminal antennal segment
elongated, spur somewhat shorter. The genus Callipterus was estab-
lished by Koch in 1855 based on all the species included without
indicating any one as the type. Some years later Passerini broke up
the genus, indicating several additional genera, and restricted Koch’s
Callipterus to juglandis as type and placed with the Lachnini. Koch’s
description of his Gaylous, very obviously does not apply to juglandis,
but rather to the forms Passerini included in the genus Myzocallis.
Later writers like Walker, Riley, Monell, Thomas, Buckton, and others,
strongly protested the procedure of Passerini and attempted to restore ~
Callipterus to its original meaning as given by Koch. Callipterus
Koch and Callipterus Passerini are two very different conceptions, as
Passerini misinterpreted Koch. Walker first suggested that tilia be
the type of Koch’s genus Callipterus and that Myzocallis be restricted
to species on Corylus and Quercus. In place of Passerini’s Callipterus
he proposed the term Callaphis, which Buckton later changed to Pty-
chodes, a tem that was still later changed to Panaphis by Kirkaldy.
It should be noticed that Koch arranged his species in a descending
order, placing first the more typical forms, and ending with the lowest,

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 137

juglandis, which was followed by the genus Lachnus. Monell aimed
to suppress the term Myzocallis altogether. There is undoubtedly a
place for Myzocallis and it should be retained, but Koch’s Callipterus
should be applied to tiliae and not to juglandis.

(80) CALLIPTERUS TILAE (Linnaeus) Walker, 1868

Not known from Minnesota bui may be looked for on Tilia.

78. Genus PTEROCALLIS Passerini, 1860. Type: Aphis alni
DeGeer, 1773. - Antennae about as long as the body; spur .of the
terminal segment slightly shorter than the base; anal plate slightly
emarginated; radial sector indistinct basally, and anal vein with a
distinct bulla on the base of the vein.

(81) PTEROCALLIS ALNI (DeGeer) Passerini, 1860
A rather small delicate form found on the leaves of Alnus.

79. Genus MYZOCALLIS Passerini, 1860. Type: Aphis coryh
Goeze, 1778. Antennae usually much longer than the body ; basal part
of the terminal antennal segment not elongated, and the spur equal
to or commonly much longer than the base; stigmal vein usually in-
distinct on basal part. The following species are known from Min-
nesota :

(82) MYZOCALLIS DISCOLOR (Monell) Wilson, 1910
Cornicles black; wings mottled with brown arezs.
(83) MYZOCALLIS ASCLEPIADIS (Monell) Wilson, 1910
Cornicles yellow; wings with brown areas.
(84) MYZOCALLIS PUNCTATUS (Monell) Wilson, 1910
Wings clear; spur slightly longer than base.
(85) MYZOCALLIS WALSHI (Monell) Baker, 1917
Wings clear; spur nearly twice the base in length.
(86) MYZOCALLIS BELLUS (Walsh) Thomas, 1879
Wings with black border; spur nearly twice the bese in length.
80. Genus TUBERCULATUS Mordwilko, 1894. Type: Aphis
quercus Kaltenbach, 1843. Abdomen with dorsal tubercles; spur
shorter than base.
(87) TUBERCULATUS ULMIFOLII (Monell)
Common on leaves of elm; a small, pale, delicate form.
81. Tribe DREPANOSIPHINI. Antennae much longer than the
body; cornicles longer than broad, enlarged basally; abdomen with

dorsal tubercles. One genus is known from Minnesota:
ay houndsoneleavesvor. soft maple... a.m. sec aes Genus DREPANAPHIS 82

138 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—19Q22

82. Genus DREPANAPHIS Del Guercio, 1909. Type: Siphono-
phora acerifolii Thomas, 1878. The excessive length of the antennae,
conspicuous dorsal tubercles with white flocculent patches, indicate a
high development similar to what is found in the Macrosiphni.

(88) DREPANAPHIS ACERIFOLII (Thomas) Del Guercio, 1909
Rather common on the leaves of soft maple.

83. Supertribe MACROSIPHEA. Size large or moderately large,
with abdomen more or less pointed posteriorly ; antennae usually longer
than the body ; spur of terminal segment very long ; sensilla on antennae
and parts of the body with a glandular, globate, or spearshaped apex,
sometimes only fingerlike and blunt; cornicles long and cylindrical,
rarely short, sometimes swollen; reticulations on cornicles usually
continuous and forming closed cells; cauda long and usually curved.
The three tribes may be separated as follows:

a. Frontal tubercles enlarged or swollen on the inner side and strongly reticu-

lated'--sensilla. clobatetate os acctac reco ere one ret Tribe MYZINI 84

b. Frontal tubercles not swollen on the inner side; cornicles very short.....

Tribe MICROSIPHINI 90
c. Cornicles long and cylindrical; sensilla on antennae spear-shaped..........
Tribe MACROSIPHINI 92
84. Tribe MYZINI. Size moderately large to small; frontal tu-
bercles with obvious swelling on the inner side, strongly reticulated
and provided with glandular hairs like those on the antennae ; cornicles
usually long and slender, cylindrical or slightly swollen apically. The
Myzini partake in form both of the Aphidini and the Macrosiphini,
but their glandular, capitate sensilla appear to be a distinct type that
may be directly traced from the Callipterini, while the Macrosiphini
are traced from the Calaphidini. The following genera are represented
in Minnesota:

a. Antennae usually shorter then the body; sensilla short in the aptera;
latéral-tuberclesu-present...nsanctacce ee eter eet er Genus MYZUS_ 85

b. Antennae longer than the body; sensilla short in aptera; no lateral
tubercles present on the abdomen; spurea sometimes with sensoria on

the “third segment =:28-. 2 Gace cate Cae eee Genus NEOMYZUS &
ce. Antennze usually equal to or shorter than the body; sensilla long in the
aptera: 10 Sensoria in Sputease...-ace een Genus CAPITOPHORUS 87

d. Antennae much longer than the body; sensilla long in the larval forms;

sensoria many and scattered on segments 3-5 in the migrant...........
Genus CRYPTOMYZUS._ 88

e. The swellings on the frontal tubercles are produced into projecting horn-
like tubercles, best seen in the spurea............ Genus PHORODON 8&9

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 2-130

85. Genus MYZUS Passerini, 1860. Type: Aphis cerasi Fabricius,
1775. Myzus partakes more of the Aphidini than any other genus
of the group. The following species are known from Minnesota:

(89) MYZUS CERASI (Fabricius) Passerini, 1860
This black species is rather common on cherry.
(90) MYZUS PERSICAE (Sulzer) Passerini, 1860

A very common species on various field and garden plants.

86. Genus NEOMYZUS Van der Goot, 1916. Type: Siphonophora
circumflexus Buckton, 1876. This genus partakes somewhat of the
Macrosiphini.

(91) NEOMYZUS CIRCUMFLEXUS (Buckton) Van der Goot, 1916
Found on Vinca and other plants. ~
(92) A species belonging here is e2lso found on the rose.

87. Genus CAPITOPHORUS Van der Goot, 1913. Type: Aplus
carduinus Walker, 1850. The numerous and long sensilla on the body,
especially in the apterous forms, relate this genus to the Callipterini.
The following species are found in Minnesota:

(93) CAPITOPHORUS CARDUINUS (Walker) Van der Goot, 1913
Common on Canada thistle.

(94) CAPITOPHORUS XANTHII (Oestlund)
On Xanthium or cocklebur.

(95) CAPITOPHORUS ROSARUM (Walker)
Found on rose
88. Genus CRYPTOMYZUS nomen nov. Type: Aphis ribis Lin-
naeus, 1758. Van der Goot considered this as the type of his genus
Myzus, but incorrectly so.
(96) CRYPTOMYZUS RIBIS (Linnaeus)
Common on currant, cupping the leaves.
89. Genus PHORODON Passerini, 1860. Type: Aphis humul
Schrank, 1801. One representative of this genus is rather abundant:
(97) PHORODON HUMULI (Schrank) Passerini, 1860
Found mostly on wild hops.
go. Tribe MICROSIPHINI. Cholodkovsky in 1908 erected the
genus Microsiphum for a very peculiar form that is not an Aphis,
a Myzus, or a Macrosiphum. It is a representative of a characteristic
tribe and fauna found on Artemisias and related plants on the great
plains. When Aphis frigidae was described as new in 1886 from
Artemisa frigida, it was seen that it did not look o behave like an
ordinary Aphis, but would eventually become a distinct genus. A
second species was also described at the same time from the same

140 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

habitat, as Siphonophora frigidae. Williams described several addi-
tional species from Artemisias and still later Gillette and Wilson have
increased our knowledge of these forms. There 1s something distine-
tive about all our Artemisia forms, tho most of them can be associated
with the Aphidini and Macrosiphini. There are some that can not so
be placed and probably represent a different stock, as indicated by
the present tribe. One would not expect the sage-bush areas of the
great western plains to be rich for collecting aphids, but a score of
species are now known and many remain to be made known. Miunne-
sota is on the border of this area and can be considered to come
within it, as several different Artemisias are found over the state, which
become infested with these western forms from time to time.

It has long been a puzzle to me to account for this peculiar sage-
bush fauna, as most of them can easily be associated with various
tribes, the Aphidini, Chaitophorini, Myzini, and Macrosiphini. They
may be looked upon as a biological group and not a phylogenetic, with
the exception of the Microsiphini. The geology of the great plains
may give us the clue as to the origin of the fauna. In the early stage
of the North American continent the western plains did not exist, as
geologists tell us, but the land was only slightly above the sea level
and the flora and fauna were probably the same for both the east-and
the west. With the gradual elevation of the west, the original flora and
fauna would tend to disappear, except for those forms that were able to
adapt themselves to the new and changed condition, and a new flora,
adapted to the changing conditions, would come in, replacing the old
and disappearing one. The Artemisias were some of those new im-
migrants, and have now become the dominant forms. The various
forms of Aphis, Chaitophorus, Myzus, and Macrosiphum persisted
only to the extent that they became adapted to the dominant Artemi-
sias; while Lachnus, Callipterus, and Pemphigus have disappeared
from those areas. One genus of the Microsiphini is well represented
in Minnesota :
acl Génus (MIC RO STP HUM 8 ra. ere ccs aie ne ee ee ne ee a OI

gt. Genus MICROSIPHUM Cholodkovsky, 1908. Type: Micro-
siphum ptarmicae Cholodkovsky, 1908. Has the general appearance
of a small Macrosiphum with very short cornicles.

(98) MICROSIPHUM ARTEMISIAE (Gillette) Wilson, 1915

Color wine red; found on Artemisia Iudoviciana.

g2. Tribe MACROSIPHINI. Size large and gradually pointed

posteriorly ; antennae usually much longer than the body; sensilla of

4 SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 141i

the antennae long and apically enlarged, arrow-shaped, spoon-shaped,
or finger-like ; sensoria are usually present on the third segment of the
spurea; head strongly emarginated in front owing to large antennal
tubercles, which are not swollen on the inner side, or very slightly so;
cornicles long, stout, and cylindrical or swollen; reticulations on the
cornicles continuous and forming cells or closed areas on the upper
part ; cauda long and usually curved, with the hairs arranged in rows
on the sides. This large tribe has usually been considered as the high-
est development of the family, or more correctly, of the subfamily.
The two subtribes may be separated as follows:

a. With typical or normal venation and other characterss.......6.........-

Subtribe MACROSIPHII 93
be Vienation abnormal! more or less) aberramt) fons: 12 castes iets fen eile

Subtribe PENTALONII 104

93. Subtribe MACROSIPHII. Typical Macrosiphini with normal
venation ; cornicles cylindrical or swollen. The subtribe may further
be considered under two divisions based on the cornicles:
aw Copniclesmeylindnical iaeniseG sce. ete Division CYLINDRICORNIA 094
bajGognicles=swollenive vo. axit ee Done e td tse es Division CLAVICORNIA 102

94. Division CYLINDRICORNIA. Cornicles cylindrical and usu-
ally strongly reticulated; sensoria usually present and restricted to
the third segment in both the spurea and the migrant. The genera of
this rather large group may again be arranged in two groups:
a. Cornicles short and with aphis-like reticulation; generalized forms...... 05
b. Cornicles long and cylindrical with closed reticulations; typical forms..... 98

95. Group Generalized Cylindricornia. Cornicles comparatively
short and the reticulation often indistinct or broken as in the Aphidini.
Two genera are represented in Minnesota:

a. Cauda short and conical; cornicles short end not much longer than the

CALI attra eee rraia i acce sic amnstaee chasse Genus MACROSIPHONIELLA 96
b. Cauda longer and Aphis-like; cornicles longer than cauda...............

Genus CATAMERGUS 097

96. Genus MACROSIPHONIELLA Del Guercio, 1911. Type:

Siphonophora atra Ferrari, 1872. A genus established by Del Guercio

for certain Aphidini-like Macrosiphini, based on the short cone-shaped
cauda and cornicles with aphis-like reticulation.

(99) MACROSIPHONIELLA SANBORNI Gillette, 1908
Found on chrysanthemum in greenhouses.

97. Genus CATAMERGUS gen. nov. Type: Nectarophora fulvae

Oestlund, 1887. The characters of the cornicles are similar to Macro-
siphoniella, but the cauda is long and Aphis-like.

142 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

(100) CATAMERGUS FULVAE (Oéestlund)

Found on Jmpatiens fulva; larvel forms pulverulent.

(101) CATAMERGUS PURPURASCENS (Oestlund)
Found on Thalictrum purpurascens; pale green.

(102) CATAMERGUS CYNOSBATI (Oestlund)
Found on Ribes cynosbati.

98. Group Typical Cylindricornia. Large and typical forms with
cornicles long and cylindrical and with an area of closed reticulations
on the apical part; sensoria present in the spurea as well as in the
migrant and usually restricted to the third segment. The following
genera are found in Minnesota:

a. Third segment of the antennae with numerous, scattered sensoria _(poly-

sensoria) ; found on Compositae.......... Genus TRITOGENAPHIS 99
b. Sensoria not so numerous and scattered; found on Rosaceae and other

PLATES HC ices peo nr eaE ie Oe eee eee Genus MACROSIPHUM too
c. Sensoria few and arranged in a single row; in the spurea the sensoria are

usually: «1-4 Wor “wantines “oso sea eee Genus ACYRTHOSIPHON tor

99. Genus TRITOGENAPHIS gen. nov. Type: Aphis rudbeckiae
Fitch, 1851. Very large and typical Macrosiphini found on Composi-
tae, and usually brown, red, vermillion, or green in color. A large
number of our Macrosiphini belong to this genus:

(103) TRITOGENAPHIS RUDBECKIAE (Fitch)

Found on Rudbeckia, Silphium, and golden glow; bright vermilion
red in color.

(104) TRITOGENAPHIS AMBROSIAE (Thomes)
Found on Iva and Ambrosia; color seal-brown or red brown

(105) TRITOGENAPHIS CHRYSANTHEMI (Oestlund)
Found on Bidens; color dark red brown.

(106) TRITOGENAPHIS ERIGERONENSIS (Thomas)
Found on Erigeron canadensis; color green.

(107) TRITOGENAPHIS LUDOVICIANAE (Oestlund)

Found on Artemisia ludoviciana; color green with white pulveru-
lent matter.

100. Genus MACROSIPHUM (Passerini) Schouteden, Igor.
Type: Aphis rosae Linnaeus, 1758. The sensoria on the antennae are
not so numerous as in the foregoing genus, and are less scattered, show-
ing a tendency to be arranged in a row and may be present on segments
3-5. It may be noticed that Passerini never once associated his Macro-
siphum with a species altho he published several papers and species
since he proposed the new term; Schouteden was the first to associate
the term as a genus with a species in 1901, and this association should
be ascribed to him and not to Passerini, who only suggested the term
and never made use of it.

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 143

(108) MACROSIPHUM ROSAE (Linnaeus) Schouteden, 1901
Found on roses; color green.

(109) MACROSIPHUM PALLIDA (Oestlund) Sanborn, 1906
A pink form found also on rose; this species has been re-
described by Patch as pseudorosac.

(110) MACROSIPHUM POTENTILLAE (Oestlund) Sanborn, 1906
A pale brown form found on Potentilla.

(111) MACROSIPHUM GERANII (Oestlund) Sanborn, 1906
Found on geranium; a pulverulent form.

(112) MACROSIPHUM FRIGIDAE (Oestlund) Sanborn, 1906
Found on Artemisia frigida; color dark green.

101. Genus ACYRTHOSIPHON Mordwilko, 1914. Type: Aphis
pisi Kaltenbach, 1843. Sensoria few, arranged in a row and usually
restricted to the third segment; spuria with only a few, 1-4, found on
the base of the third segment. Large green or pale forms found on
various plants, mostly herbs.

(113) ACYRTHOSIPHON PISI (Kaltenbech) Mordwilko, 1914

Found on various Legwmenosaec; color green.

(114) ACYRTHOSIPHON GRANARIUM (Kirby) Mordwilko, 1914.
Found on Graminaceae; color pale brown.

(115) ACYRTHOSIPHON SOLANIFOLII (Ashmead)
Found on cruciferous plants and potato.

102. Division CLAVICORNIA. Cornicles very long and swollen,
usually without closed reticulations except a few near the apex of the
cornicles. At present a great many different forms are considered
under one genus:

a. Cornicles swollen; large Macrosiphum-like forms.....................-. 103

103. Genus AMPHOROPHORA Buckton, 1876. Type: Ampho-
rophora ampullata Buckton, 1876. A number of genera that Mord-
wilko recognizes for the European fauna have not yet been applied to
our American representatives.

Ge) AMPHROPHORA NABALI (Oestlund)

Found on Nabalus albus; a large and conspicuous form, with
numerous small sensoria on segments 3 to 5 in the migrant.
(117) AMPHOROPHORA SONCHI (Oestlund)
Found on Sonchus oleracea; similar to nabali but with fewer and
larger sensoria on the third and the fourth segments.
(119) AMPHOROPHORA RUBICOLA (Oéestlund)
Found on growing stalks of Rubus; sensoria restricted to the third
segment.

144 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

(120) AMPHOROPHORA AMPULLATA Buckton, 1876
What is considered to be this species was once taken at Minne-
apolis on the Ostrich fern, but has not since been seen and may
have been an escaped form from some greenhouse; sensilla on
antennae short and small.

104. Subtribe PENTALONII. The Pentalonii have certain ab-
normalities in venation and otherwise that separate them from the
typical Macrosiphii. A very interesting biological question is asso-
ciated with this peculiarity of tropical or subtropical forms. One
representative is known from Minnesota:

a. Hind wings much reduced and without oblique veins....................
Genus MICROPARSUS 105

105. Genus MICROPARSUS Patch, 1909. Type: Microparsus
variabilis Patch, 1909. A peculiar genus characterized by the media
of the fore wings with only one branch, and by the reduced hind
wings with only a stump of an oblique vein or altogether wanting.

(121) MICROPARSUS VARIABILIS Patch, 1909

Found on tick trefoil or Desmodium.

106. Subfamily PEMPHIGINAE. 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; reduction in venation is also carried
further in this subfamily than in the preceding. The subfamily is
typically subterraneous or protected in habitat, and found in folds
of leaves, in crevices of bark, or in galls. Positive pemphigian char-
acters are seen in the position of the antennae and in the great develop-
ment of the dermal glands. The antennae are usually shorter than
half the length of the body, and inserted on the under side of the head
in depressions not seen from above; sensoria are often crowded and
therefore usually transverse or annulate; media of the fore wings
usually simple, or with one branch, rarely with two branches ; cornicles
very short and appear as pores, or are wanting. It may be noticed
that in Lachnea the antennae are inserted on the sides of the head in
front of the eyes, in the Aphidea and the Macrosiphea lines they tend
to become dorsal, while in the Pemphiginae they have moved to a
ventral position. Only one series is recognized :

a.” The Mindarea=Pemphigea - series. 22): car. enacts a ie te ene ere ee 107

107. Series MINDAREA-PEMPHIGEA. The characters of the
series are the same as those for the subfamily. The following super-
tribes are at present recognized :

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 145

a. Radial sector arising from behind the stigma; found on Conifera........
Supertribe MINDAREA 108

b. Sector arising from the middle of the stigma; fundatrix with six segments

to the antennae; sexes with rostrum; found on woody plents..........
Supertribe PHYLLAPHIDEA 111

c. Pena usually with five segments to the antennae, sometimes with six ;

sexes without rostrum; found in folded or twisted leaves, sometimes in

(Se US Pepe aCe ene Re eu inae iene ine (ae MA Supertribe SCHIZONEUREA tar
d. Fundatrix usually with only four segments to the antennae; sexes without
rostrum; found in galls and on roots........ Supertribe PEMPHIGEA 129

108. Supertribe MINDAREA. In the Mindarea the stigmal vein
arises from the base or back of the stigma and runs as a straight vein
to the margin of the wing. This is considered as a very primitive
condition that is known also from fossil forms. Only one tribe is
known
ies Ware thea oye. MY LIUINIDUANIRG TIN [I lise os 6 a ceca aicela 8 cicteieteap ino cin io. a oto isos encase 109

tog. Tribe MINDARINI. With the same characters as the super-
tribe. Only one genus is known at present:

Fee Sia nbs PING DANN WIS oer AER ed a ATA Are STE Be Corea h se abio nce co Achy irae sae 110

110. Genus MINDARUS Koch, 1857. Type: Mindarus abietinus
Koch, 1857. Antennae 6-jointed; sensoria round or oval; cauda
obvious ; the sexes are both apterous and provided with rostrum. Found
exclusively on Conifera.

(122) -MINDARUS ABIETINUS Koch, 1857

Found on pine and spruce, twisting the needles.

I1k. Supertribe PHYLLAPHIDEA. The position of the antennae
indicate the Pemphiginae relations of all the tribes included. Some
Phyllaphidint and Vacunini show Callipterini characters, while the
Anoectini and Vacunini also show Chaitophorini relations. The fol-
lowing tribes may be recognized:

a. Media twice branched; sexes with male alate and female apterous........
Tribe PHYLLAPHIDINI 112

b. Media with only one branch; sexes sometimes both alate or both apterous. .
Tribe TAMALIINI 114

c. Antennzee with long hairs; sexes both small and apterous.................
Tribe ANOECIINI 117

d. Hind wing with only one oblique vein; sexes alate or apterous..........
Tribe VACUNINI 119

Tribe PHYLLAPHIDINI. Forms living free on plants. pro-
tected by abundant secretion ; media of fore wings with two branches :
a Genicu Gree WMC em orien se a... t edad ais hs pa s,s 113

146 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

113. Genus PHYLLAPHIS Koch 1857. -Type: Apmis jagt- Ling
naeus, 1758. Cauda globate; anal plate slightly emarginated ; sensoria
oval.

(123) PHYLLAPHIS FAGI (Linnaeus) Koch, 1857
Not known from Minnesota.

114. Tribe TAMALIINI. Type: Pemphigus coweni Cockerell,
1g05. Antennae 6-jointed; cauda short and broad, not extending.
beyond the anal plate; cornicular pores slightly raised above the sur-
face; media with one branch. Found in gall-shaped folds or between
united leaves. ‘Two genera may be recognized:

a. Found in pod-like folded leaves of Arctostaphylus..... Genus TAMALIA 115
b. Found in folded margins on the leaves of oak, or between united leaves..
Genus STEGOPHYLLA 116

115. Genus TAMALIA (Pergande) Baker, 1920. Type: Pemphi-
gus coweni Cockerell, 1905. Oviparous female sometimes alate ; media
with 6ne branch in the fore wings; cauda entire, short, and rounded ;
anal plate not divided.

(124) TAMALIA COWENI (Cockerell) Baker, 1920
Found in folded leaves of Arctostaphylus.

116. Genus STEGOPHYLLA gen. nov. Type: Phyllaphis querci-
cola Baker, 1916. The first generation is found in folded margins
on oak leaves. Later generations spread on under side of leaves, or
between those folded by other insects. Antennae 6-jointed ; media of
fore wings with only one branch; in the sexuales both the male and

the female are apterous; summer generations with conspicuous floc-
culent matter.

(125) STEGOPHYLLA QUERCICOLA (Baker)
Found on white oak.

117. Tribe ANOECIINI. Antennae 6-jointed, with rather large,
round or oval sensoria, and covered with long hairs as in the Chaito-
phorini; media with only one branch; cauda short, broad and rounded
like the anal plate; sexes small and both apterous and provided with
rostrum. One genus is known: -

Rs ee Ren aan SP On Genus ANOECIA 118

118. Genus ANOECIA Koch, 1857: Type: Aphis corni Fabricius,
1775. One species is sometimes found in Minnesota:

(126) ANOECIA CORNI (Fabricius) Koch, 185

Found on dogwood. :

a. Characters as for the tribe

lod

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 147

119. Tribe VACUNINI. Antennae 5-jointed; body and append-
ages more or less hairy as in Chaitophorini.
Qe (EMSS: WAC WIN Ac pres Coan Since eRe cm cates cM RM ger er eater op Sara el 120
120. Genus VACUNA (Heyden) Kaltenbach, 1843. Type: Aplus
dryophila Schrank, 1801. Heyden included coccinea and dryophila
without indicating either as type. His description of the genus would
imply dryophila as the type rather than coccinea, which he interpreted
as also having five segments to the antennae like dryophila. Kalten-
bach restricted the genus to dryophila and placed coccinea in Boyer’s
genus Phylloxera. Hence Vacuna (Heyden) Kaltenbach, 1843 in sen.
str. is monotypic with dryophila as the type, as implied and accepted
by most authors since the time of Kaltenbach. There is no good reason
for discarding this well known term. Formerly authors endeavored
to conserve the older terms; modern writers too often discard them on
mere technicalities. Neither Heyden nor Kaltenbach recognized types
‘in the modern chronological sense but their genera were erected on all
the species included. Heyden had no true conception of the genus
Phylloxera, and the species in hand he attempted to interpret as a
Vacuna. Jxaltenbach corrected this and restricted Vacuna as now
understood. ,

(127) VACUNA DRYOPHILA (Schrank) Heyden, 1837

Not known from Minnesota.

121. Supertribe SCHIZONEUREA. Sexes small and> without
rostrum; fundatrix with 6, 5, or 4 segments to the antennae; media
with one branch or simple; found in folded leaves, in nests of ants,
or in true galls. The following tribes may be separated:

a. Fundatrix with 6 or 5 segments; media with one branch; cornicles usually

present as pores; antennae of migrant 6-jointed; found in folded leaves..
Tribe SCHIZONEURINI 122

b. Cornicles wanting; media of fore wings simple; antennae of migrant with

5 or 6 segments; found in nests of ents..............- Tribe FORDINI 124
c. Cornicles wanting; media of fore wings with one branch or simple;

fundatrix with only four segments to the antennae; migrant with 5 or

Gratoundtineatnuercallsteascry oeimc. elect rc Tribe TETRANEURINI 125

122. Tribe SCHIZONEURINI. Media of fore ‘wings with one
branch; transverse veins in hind wings far apart at place of origin;
migrant with six segments to the antennae ; fundatrix with five, or some-
times with six segments ; wax glands composed of large facets arranged
concentrically. One genus is represented in Minnesota:

a; ~ Medtamynithigome sbtanchioncr = stkean secre eee Genus SCHIZONEURA 123

148 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22

123. Genus SCHIZONEURA Hartig, 1837. Type: Aphis lanigera
Hausmann, 1801. Eriosoma was used by Leach in a broad and loose
sense, contrasted with Aphis and is equivalent to Pemphiginae as a
subfamily name. “‘Eriosoma has its body covered by wooly matter ;
its abdomen has neither horns nor tubercles, and its antennae are short.
The body of Aphis is naked, and the abdomen is furnished with a
tubercle, or hotnlike process on each side.” (Trans. Hort. Soc. Lon-
don. Vol. 3, 1820). Schizoneura and Pemphigus have been accepted
by most writers since the time of Hartig, and have gone so extensively
into the literature, that it would be to a considerable disadvantage to
change it now on the slight claim that Leach may have for his Erio-
soma. The following species are found in Minnesota :

(128) SCHIZONEURA LANIGERA (Hausmann) Hartig, 1841

Rather common on apple; the winter form is the rosette on Amer-
ican elm.

(129) SCHIZONEURA AMERICANA Riley, 1879
Folding the leaves of elm from the sides.
(130) SCHIZONEURA RILEYI Thomas, 1879
Found on the trunk in crevices or injuries on elm.
124. Tribe FORDINI. Cornicles wanting; media of fore wings
simple; hmd wings with two transverse veins. Found in nests of ants
and underground on roots. None are known from Minnesota, but

Forda with five segments to the antennae, and Geoica with six, may
be looked for.

125. Tribe TETRANEURINI. Media simple or with one branch;
fundatrix with four segments to the antennae ; migrant with five or six ;
no cornicles present. Found in galls and on roots of plants. The
following genera are found in Minnesota:

a. Media simple; hind’ wings with one transverse vein...<1 05... ..5.:+ 05.0 5-

Genus TETRANEURA 126

b. Media with one branch; hind wings with one transverse vein...........

Genus COLOPHA 127

c. Media with one branch; hind wings with two transverse veins............

Genus MELAPHIS 128

126. Genus TETRANEURA Hartig, 1841. Type: Aphis ulmi Lin-

naeus, in part, 1758. Media of fore wings simple; hind wings with
only one transverse vein; found in galls on Ulmus.

(131) TETRANEURA ULMI (Linnzeus in part) Hartig, 1841

Found in small galls on European elm; not known from Minnesota.

SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 149

127. Genus COLOPHA Monell, 1877. Type: Byrsocrypta ulmi-
cola Fitch, 1859. Media typically with one branch, but often simple;
hind wings with one transverse vein; galls are formed on leaves of
Ulmus, summer generations underground on roots:

(132) COLOPHA ULMICOLA (Fitch) Monell, 1877

The well known Cockscomb gall on American elm; summer
generations are found on roots of grasses.

128. Genus MELAPHIS Walsh, 1867. Type: Byrsocrypta rhots
Fitch, 1866. Media usually simple, but often with one branch; hind
wings with two transverse veins.

(133) MELAPHIS RHOIS (Fitch) Walsh, 1867

Found in rather large thin walled galls on Rhus.

(134) MELAPHIS ULMIFUSUS (Walsh)

Found in large sacklike galls on Red elm or Ulmus fulva.

129. Supertribe PEMPHIGEA. Sensoria transverse or oval, not
annulate, and usually not extending around the segment ; the transverse
veins of the hind wings usually arising close together and with the
bent radius have a tridentate appearance ; cornicles wanting ; wax glands

composed of small and irregularly placed facets:

a. Migrant with 6-jointed antennae; fundatrix with five segments; wax
glands present on the head as well as on the rest of the body; found
iilehwWaStedeleaveSuOr since ania. cuustok beck see Tribe PROCIPHILINI 130

b. Migrant with 6-jointed antennae: fundatrix with only four segments;
wax glands not present on the head; spring generations found in true
CBINIS "ghar as Sot Pith PS Gh eT ORE a ae ie, oe Tribe PEMPHIGINI 133

c. Migrant with three to five segments to the antennae; fundatrix with four
segments ; hind wings with one or two transverse veins; the cubital vein
appearine-as a branch of the anal........... Tribe HORMAPHIDINI 136

130. Tribe PROCIPHILINI. Large forms with large wax glands
on the head as well as on the abdomen; usually found exposed or in
crumpled leaves; the following genera are known from Minnesota:

a. Found in twisted leaves or free; sensoria transverse..............+++20%

Genus PROCIPHILUS 131
br Having free on their host plant: sensoria’ oval<:./e.>..%.0..c. be wens
Genus NEOPROCIPHILUS 132
131. Genus PROCIPHILUS Koch, 1857. Type: Aphis bumeliae
Schrank, 1801. Antennae rather long for a Pemphiginae, basal part
of the terminal segment elongated. Found in twisted leaves on ash
and alder.
(135) PROCIPHILUS FRAXINIFOLII (Riley) Pergandi, 1912
Found in twisted leaves on ash.

150 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22

(136) PROCIPHILUS APPROXIMATUS Patch, 1917
A very large form also found on ash.

(137) PROCIPHILUS TESSELLATA (Fitch) Pergandi, 1912
Winter host soft maple, summer host alder.

132. Genus NEOPROCIPHILUS Patch, 1912. Type: Pemphigus
attenuatus Osborn and Sirrine, 1893. Strongly covered with white
matter ; living free on the host plant.

(138). NEOPROCIPHILUS: ATTENUATUS (Osborn and Sirrine)

Patch, 1912
Found on the stems of Smilax.

33. Tribe PEMPHIGINI. Antennae of migrant 6-jointed; in
fundatrix 4-jointed; no wax glands on the head, or rarely so; media
simple and hind wings with two oblique veins arising close together ;
wax glands made up of a number of small, irregularly arranged, facets ;
spring generations usually found in galls. The following genera are
represented in Minnesota:

a. Spur of the terminal segment short................ Genus PEMPHIGUS 134
b. Spur of the terminal segment much longer than the basal part............

Genus MORDWILKOJA 135

134. Genus PEMPHIGUS Hartig, 1837. Type: Aphis bursaria

Linnaeus, 1758. Media of the fore wings simple; sensoria on the

antennae transverse or oval, usually not extending around the segment ;

spur very short. Spring generations are usually found ‘in galls or

folds on leaves, and summer generations on roots of plants and on
Compositae. The following species are known from Minnesota :

(139) PEMPHIGUS BURSARIUS (Linnaeus) Hartig, 1841 is
Found on Lombardy poplar, Populus nigra, in galls on the petiole.
Rather plentiful around Minneapolis.

(140) PEMPHIGUS POPULICAULIS Fitch, 1859 e
Found in galls on the petiole of cottonwood; close to the bese of
the leaf and with an oblique opening.

(141) PEMPHIGUS POPULITRANSVERSUS Riley, 1879
Found in galls on the middle of the petiole of cottonwcod leaves,
with a small transverse opening.

(142) PEMPHIGUS POPULIGLOBULI Fitch, 1859
Found in a globular gall near the base of the leaf on belsam poplar.

(143) PEMPHIGUS POPULIMONILIS Riley, 1879

Found in small galls arranged in row along the midvein on the
leaves of balsam poplar. (Thecabius Koch.)

SYNOPTICAL KEY. TO THE APHIDIDAE OF MINNESOTA I5I

(144) PEMPHIGUS POPULIVENAE Fitch, 1859
Found in a compressed gall on the midvein of balsam poplar.
(Pachypappa Koch.)

(145) PEMPHIGUS PSEUDOBYRSA (Walsh) Thomas, 1879
Found in a widely open, somewhat compressed gall on the midvein of
Cottonwood leaves; eventually the whole leaf folds ventrally from
the sides. (Pachypappa Koch.)

135. Genus MORDWILKOJA Del Guercio, 1909. Type: Byrso-
crypta vagabunda Walsh, 1862. Spur of the terminal antennal segment
very long for a Pemphiginae; much longer than the basal part; the
marginal sensoria are distributed on the spur.

(146) MORDWILKOJA VAGABUNDUS (Walsh) Del Guercio, 1909

The spring generation forms a very large and irregular gall et the
tip of the branches of cottonwood.

136. Tribe HORMAPHIDINI. Antennae of the migrant 3- to
5-jointed; sensoria annulate; cornicles usually wanting; cauda distinct
and globate, and anal plate emarginated; media of the fore wings
simple, and the cubitus appearing as a branch of the anal; hind wings
with one or two oblique veins. The Hormaphidini represent an ex-
treme development of the Pemphiginae line, and should, probably,
be included with the Vacunini in the Phyllaphidea group. Two genera
are recognized in the tribe:

a. Antennae have three segments in the migrant...... Genus HORMAPHIS 137
b. Antennae have five segments in the migrant..Genus HAMAMELISTES 138

137. Genus HORMAPHIS Osten-Sacken, 1861. Type: Byrso-
crypta hamamelidis Fitch, 1851. Fundatrix and migrant with only
three segments to the antennae. Galls are found on witch-hazel. The
genus is not known from Minnesota.

138. Genus HAMAMELISTES Shimer, 1867. Type: Hamame-
listes spinosus Shimer, 1867. The fundatrix with four segments to
the antennae and the migrant with five. Forms a spinous gall on
witch-hazel.

(148) HAMAMELISTES PAPYRACEAE (Oestlund)

Pergande considered this the seme as spinosus, but this may be
considered an open question. The above form is rather common
here as well as in the northern parts of the state, one or two hun-
dred miles from the nearest witch-hazel brush, which enters the
state only in the extreme southeastern corner.