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ILLINOIS TREES AND SHRUBS:
THEIR Insect Enemies
Eve: EN GES-A
meEeINOIS NATURAL HISTORY SURVEY
Cicwdar 47
NATURAL
HISTORY SURVEY
IDDADV
STATE OF ILLINOIS
Wittiam G. Srrartron, Governor
DEPARTMENT OF REGISTRATION AND EDUCATION
Vera M. Binks, Director
BOARD OF NATURAL RESOURCES AND CONSERVATION
Vera M. Binks, Chairman;
A. E, Emerson, Ph.D., Biology; L. H. Tirrany, Ph.D., Forestry; Wauter 11. Newnouse,
Ph.D., Geology ; Rocer ApaMs, ie veIDES IDPNVes- Chemistry; la
Rosert H. ANDERSON, B.S.C.E., Engineering; W.
Everitt, E.E., Ph.D., Representing the President of the University of Illinois; DetyteE W. ‘Morris, Ph.D., Presi-
dent of ‘Southern Illinois University
NATURAL HISTORY SURVEY DIVISION, Urbana, Illinois
SCIENTIFIC AND TECHNICAL STAFF
Har.ow B. Mitts, Ph.D., Chief
Bessie B. East, M.S., Assistant to the Chief
Section of Economic Entomology
Georce C. Decker, Ph.D., Entomologist and Head
J. H. Biccer, M.S., Entomologist
L. L. Encuisu, Ph.D., Entomologist
Wiruis N. Bruce, Ph.D., Associate Entomologist
Norman Gannon, Ph.D., Associate Entomologist
W. H. Lucxmann, Ph.D., Associate Entomologist
Joun D. Briccs, Ph.D., Associate Entomologist
Ronatp H. Meyer, M.S., Assistant Entomologist
Joun D. Pascuxe, Ph.D., Assistant Entomologist
Rosert SnetsincER, M.S., Field Assistant
Joun P. Kramer, M.S., Laboratory Assistant
Eucene M. Bravi, M.S., Research Assistant
Ricuarp B. Dysart, B.S., Technical Assistant
Apert Savaxo, B.S., Technical Assistant
Eart STapELBACcHER, B.S., Technical Assistant
Sue E. Watkins, Technical Assistant
H. B. Petry, Ph.D., Extension Specialist in Entomology*
Stevenson Moore, III, Ph.D., Extension Specialist in
Entomology*
H. B. Cunnincuam, M.S., Research Associate*
Joun W. Matteson, M.S., Research Associate*
Crarence E. Wuire, B.S., Research Assistant*
Joun Artuur Lowe, B.S., Research Assistant*
Cuar.es Le Sar, B.S., Research Assistant*
Loutse Zincrone, B.S., Research Assistant*
Mary E. Mann, R.N., Research Assistant*
Section of Faunistic Surveys and Insect Identification
H. H. Ross, Ph.D., Systematic Entomologist and Head
Mixton W. SANDERSON, Ph.D., Taxonomist
Lewis J. STANNARD, JR., Ph.D., Associate Taxonomist
Puitip W. Smitrn, Ph.D., Associate Taxonomist
Leonora K. Gtroyp, M.S., Assistant Taxonomist
R. B. Seranper, Ph.D., Assistant Taxonomist
Xpwarp L. Mocxrorp, M.S., Technical Assistant
Tuetma H. Overstreet, Technical Assistant
Section of Aquatic Biology
Georce W. Bennett, Ph.D., Aquatic Biologist and Head
Wirutam C. Starrett, Ph.D., Aquatic Biologist
R. W. Larimore, Ph.D., Associate Aquatic Biologist
Davi H. Buck, Ph.D., "Associate Aquatic Biologist
Rosert C. Hirtipran, Ph.D., Associate Biochemist
Donatp F. Hansen, Ph.D., "Assistant Aquatic Biologist
Wuuiam F. Cuirvers, MS., Assistant Aquatic Biologist
Joun C. Crattey, B.S., Field Assistant
Ricwarp E. Bass, Field Assistant
Rozsert D. Crompton, Field Assistant
CONSULTANTS: Herrerotocy, Hosarr M. Smiru,
Ph.D., Associate Professor of Zoology,
Section of Aquatic Biology—continued
M. A. Wuiracre, M.A., Assistant Aquatic Biologist*
Arnotp W. Fritz, B.S., Field Assistant*
Davip J. McGinty, Field Assistant*
Pau Frey, B.S., Laboratory Assistant*
Section of Applied Botany and Plant Pathology
J. Cepric Carter, Ph.D., Plant Pathologist and Head
J. L. Forsperc, Ph.D., Plant Pathologist
G. H. Borewe, M.S., Associate Botanist ,
Rosert A. Evers, Ph.D., Associate Botanist !
R. J. Campana, Ph.D., Associate Plant Pathologist
Rospert Dan NEELy, Ph. D., Assistant Plant Pathologist’
E. B. Hime ick, M.S., Assistant Plant Pathologist H
Rovenia F, Fitz- GERALD, B.A., Technical Assistant
Section of Wildlife Research
Tuomas G. Scott, Ph.D., Game Specialist and Head
Ratpo E. YEATTER, Ph.D., Game Specialist
Cart O. Monr, Ph.D., Game Specialist
F. C. Betirose, B.S., Game Specialist
Ricuarp R, Graser, Ph.D., Associate Wildlife Specialist
W. R. Hanson, Ph.D., Associate Game Specialist
H. C. Hanson, M.S., Associate Game Spectalist
Wiriiam R. Hawkins, B.A., Technical Assistant
Frances D. Rossins, B.A., Technical Assistant
Vireinia A. Lancpon, Technical Assistant {|
Howarp Crum, Jr., Field Assistant ‘
Rexrorp D. Lorp, Ses Project Leader* H
FREDERICK GREELEY, Ph.D., Project Leader* “
Guen C. Sanperson, M.A., Project Leader* {
Pau. A. Vous, Jr., B.S., Project Leader* q
Jacx A. Exuis, M.S., Project Leader*
Ronatp F. Lasisxy, MS., Project Leader* H
Tuomas R. B. Barr, M.V.Sc., M.R.C.V.S., Research i
Assistant* f
Bossre Joe Verts, M.S., Field Mammalogist* f
Section of Publications and Public Relations y
James S. Ayars, B.S., Technical Editor and Head -
Buancne P. Younc, B.A., Assistant Technical Editor —
Diana R. Braverman, B.A., Assistant Technical Editor )
Wituiam E. Crark, Assistant Technical Photographer
Wiruram D. Woon, B.S., Technical Assistant \q
Technical Library i
Rut R. Warrick, B.S., B.S.L.S., Technical Librarian —
Next Mites, M.S., B.S.L.S., Assistant Technical |
Librarian a
University of Illinois —
Parasitotocy, Norman D. Levine, Ph.D., Professor of Veterinary Parasitology and of Veterinary Research, Universit: —
of Illinois; Wirtn.tre ResearcuH, Wittarp D. Kurimstra, Ph.D., Associate Professor of Zoology and Director o-
Co-operative Wildlife Research, Southern Illinois University.
*Employed on co-operative projects with one of several agencies: University of Illinois, Illinois Aecelara
Extension Service, Illinois Department of Conservation, United States Army Surgeon General’s Office, United State)
Department of Agriculture, United States Fish and Wildlife Service, United States Public Health Service, and a)
This paper is a contribution from the Section of Economic Entomology.
Circular 47 Printed by Authority of
STATE OF ILLINOIS ° William G. Stratton, Governor
DEPARTMENT OF REGISTRATION AND EDUCATION ® Vera M. Binks, Director
NATURAL HISTORY SURVEY DIVISION °® Harlow B. Mills, Chief
ILLINOIS TREES AND SHRUBS:
THEIR Insect Enemies
La Ee E NeGiLehSeH
PELINOIS NATURAL HISTORY SURVEY
the State of Illinois
May, 1958
CONTENTS
About Insects 2 :
Aphids or Plant Lice .
Scale Insects .
Borers afer
Leaf Eaters .
Mites
Gall-Pr oducing ‘Insects
and Mites . ne
About Trees and Shrubs
and Their Pests :
Ailanthus (Tree of Heaven)
Ailanthus Webworm
Cynthia Moth
Arborvitae
Bagworm .
Arborvitae Leaf Miner
Spruce Spider Mite
Juniper Scale
Ash
Red- Headed Ash Bor er
Ash Borer = . :
Oystershell Scale :
Fall Webworm
Birch . 2
Bronze Birch Borer
Birch Skeletonizer
Boxelder .
Boxelder Bug
Boxelder Aphid . . :
Eastern Tent Cater pillar P
Boxwood :
Boxwood Leaf Miner
Catalpa
Catalpa Sphinx -
Comstock Mealybug
Crabs and Hawthorns .
Yellow-Necked Caterpillar
Woolly Hawthorn Aphid
European Red Mite
San Jose Seale. . :
Hawthorn Leaf Miner ;
Dogwood :
Dogwood Borer
Dogwood Scale .
Douglas Fir . :
Cooley Spruce - Gall 1 Aphid
Bolin oc Sas
Spring Canker worm .
White-Marked Tussock Moth .
Fall Webworm .
Elm Leaf Beetle
European Elm Scale
Scurfy Scale .
Putnam Scale .
Elm Leaf Aphid .
Woolly Elm Aphid . .
Elm Cockscomb Gall Aphid «
Elm Borer
wwnwnrdrr
w
£0 00 VV I TT OT OT OT CO CO CO
Smaller European
Elm Bark Beetle ;
Banded Elm Lease :
Mites :
Euonymus. .
Euonymus Scale
Hackberry
Hackberry Nipple Gall Psyllid 3
Witches’-Broom
Hickory . :
Yellow- Necked Caterpillar P
Hickory Bark Beetle .
Hickory Gall Phylloxera .
Hickory Horned Devil
or Regal Moth
Juniper
Juniper Scale
Juniper Webworm
Juniper Bark Beetle
Spruce Spider Mite
Bagworm
Lilac F
Lilac Borer Shes
Oystershell Scale
Linden . :
Elm Spanwor m
Locust
Locust Borer
Bagworm
Locust Mite
Mimosa Webworm
Maple .
Cottony “Maple Stale oa
Maple Bladder-Gall Mite
Green-Striped Mapleworm .
Flatheaded Apple ° Tree Borer i
Aphids
Pigeon Tremex
Oak
Borers . 2
Periodical Cicada :
May Beetles .
Twig Pruner
Oak Kermes
Leaf Miners
Gall-Producing Insects :
Pine Sy oc ee
Sawflies
White-Pine Weevil
Pine Needle Scale
Pine Bark Aphid. .
European Pine Shoot Moth .
Nantucket Pine Moth
Zimmerman Pine Moth
Poplar
Poplar Borer
Cottonwood Borer .
Poplar and Willow Borer
tet a
a
—- ---—
eS ee
Carpenterwor ile :
Cottonwood Leaf Beetle
Poplar Tent Maker
Oystershell Seale .
rivet: : ... t
Privet Thrips
Redbud .
Oystershell Scale .
Two-Spotted eee Mite
Spirea . . ;
Spirea Aphid
Spruce ..
Spruce Spider Mite . .
Cooley Spruce Gall Aphid
Eastern Spruce Gall nee
Spruce Bud Scale
Spruce Budworm
Pine Needle Scale
Sycamore : ;
Sycamore Lace Bug :
Bagworm Men
Borers .
Tuliptree .. ‘
Tuliptree Scale
Tuliptree Aphid
Walnut...
Walnut Cater pillar :
Black Walnut Curculio
Willow
Willow Aphid.
Bagworm
Borers . :
Oystershell Seale :
Yew (Taxus)
Black Vine Weevil
Fletcher Scale
Termites
Taxus Mealybug
Potential Insect Enemies
Japanese Beetle
Gypsy Moth. . .
Brown-Tail Moth
About Insecticides ;
About Spray Equipment
And Its Use
Index
Spray Breparation Tables
Control Measures
The kodachreme for the cover and most of the photographs for this
circular were taken by William E. Clark of the Illinois Natural History Sur-
yey. Photographs from outside agencies are credited to those agencies.
TO USERS OF THIS CIRCULAR
Control measures referred to in this circular are listed on
pages 90, 91, and 92.
Trombone-type sprayer in use. This is an inexpensive sprayer that is con-
venient for applying chemicals to limited numbers of shrubs and small trees.
ILLINOIS TREES AND SHRUBS:
THEIR Insect Enemies
Pee NG | Sue
egardless of their size or cost, trees and shrubs used as orna-
mentals may be highly prized by their owners as sources
of shade or beauty. An important aspect of the care of orna-
mentals is the prevention of insect damage. Such plants may be
severely damaged or even destroyed unless their owners have at
least an elementary knowledge of insect pests and the ways in
which they can be controlled. To provide help in the recognition
of insect pests of trees and shrubs used as ornamentals and to
suggest specific measures for control of these pests is the pur-
pose of this circular.
Insects may damage trees and shrubs in many ways. A col-
ony of ravenous caterpillars may strip the foliage from twigs
and branches; hordes of aphids may suck the sap from new
shoots and leaves, causing them to wilt or to grow abnormally;
tiny scale insects may encrust branches and twigs, withdrawing
enough food to kill plants outright; borers of many kinds may
invade the bark and wood, seriously injuring or killing plants;
more subtle but as serious is the damage caused by those insects
that carry fungus or virus diseases.
ABOUT INSECTS
The first essential for effective control of insect pests is vigi-
lance and an interest, which may be acquired, in looking for in-
sects and signs of their damage. To detect the presence of
insects before they cause serious damage to valuable trees and
shrubs, one should carefully examine the plants at least once a
week during the growing season. One should examine deciduous
trees in winter, also, when scale insects on them may be seen
more easily than when trees are in leaf.
The second essential is at least an elementary knowledge of
insects and the ways they reproduce and grow. For example,
one should know that while most kinds of insects lay eggs, some,
like most of the aphids, give birth to living young. The eggs of
insects are of various sizes, shapes, and colors; most of them are
small in size and are not easily seen. They are laid singly or in
clusters, hidden or in conspicuous places. With few exceptions,
2 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
insect eggs cause little or no damage, but many of the animals
that hatch from the eggs are destructive.
Insects develop by metamorphosis, or change. The young
of some kinds, boxelder bugs for example, look like the adults
and reach maturity through a series of molts. The young of
kinds that look unlike the adults are called larvae, grubs, cater-
pillars, or worms. Eggs deposited by moths and butterflies pro-
duce caterpillars that feed ravenously and molt several times
before they reach maturity. The caterpillars change to pupae
(latent stage) for transformation to moths or butterflies. The
growth pattern of beetles is similar to that of moths and butter-
flies. The young of beetles are often called grubs.
The following paragraphs contain information about sev-
eral kinds of insects and the ways in which they feed.
Aphids or Plant Lice.—There is a species of aphid for al-
most every species of plant. Aphids are sucking insects, fragile
and awkward in appearance. They are most commonly green,
pink, or black in color. Each aphid, only one-sixteenth to one-
eighth inch long, is well equipped with a stout beak through
which it draws great quantities of plant juice as it feeds from
place to place on tender plant tissue. Heavy infestations of
aphids usually produce a noticeable amount of honeydew, on
which a sooty mold may grow. Aphids have an enormous repro-
ductive capacity. Fortunately they have many natural enemies.
Lady beetles, both larvae and adults, fatten themselves on
aphids, and the larvae of tiny parasitic wasps feed within them.
Scale Insects.—Scale insects, small and inconspicuous, are
likely to be overlooked until the branches of infested trees or
shrubs are encrusted with them. They are sucking insects that
live most of their lives under protective shells or scales. They
may kill branches, limbs, and whole trees. Each insect is a mere
sack of protoplasm with a threadlike beak thrust into the tissue
of the plant it feeds upon. The female in most species of scale
insects deposits eggs under her shell. The eggs produce crawlers
that move away from the shell to find suitable feeding places.
When the crawlers settle and begin to feed, each makes a shell
for its own protection.
Borers.—Most borers that attack trees or shrubs are the
larvae of beetles or moths. They hatch from eggs deposited on
the bark of a tree or shrub. Soon after hatching, they bore into
the wood of the plant. Healthy, vigorous trees are unattractive
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 3
to borers. Newly planted trees suffering from transplanting
shock, and older trees growing in unfavorable places where little
moisture or food is available, become attractive to the pests.
Leaf Eaters.—Severe damage by this group of pests is con-
spicuous and easy to detect. In many cases, however, damage
is not observed until serious defoliation has occurred. The prin-
cipal leaf eaters are beetles and their larvae (grubs) and the
larvae (caterpillars) of moths and sawflies. Damage by these
pests is most likely to occur in the spring and early summer.
Mites.—Especially destructive to evergreens, these animals,
barely visible to the naked eye, have great reproductive power
and attack plants in large numbers. They injure plants by
rasping the leaf surfaces and removing the plant juices. Tech-
nically, mites are not insects, although closely related to them.
Gall-Producing Insects and Mites.—Galls are abnormal
growths appearing as warts or bumps or attractive-looking balls
on leaves and twigs. They are of many shapes and sizes, but
each kind is characteristic of the animal that produces it. The
production of some galls is stimulated by tiny mites too small
to be seen with the naked eye. The production of others is stim-
ulated by flies, aphids, and small wasps. A part of the life cycle
of the gall-producing animal is spent inside the gall. Most galls
do not cause serious damage to the plants on which they are
found.
ABOUT TREES AND SHRUBS AND THEIR PESTS
In the discussion that follows, the host plants are arranged
alphabetically. Each pest and the nature of its damage are
briefly described; notes on the life history are given for each of
the common and destructive pests. The control measures are
numbered and are found at the end of the circular, pages 90, 91,
and 92, along with convenient dilution tables, page 89.
AILANTHUS (TREE OF HEAVEN)
Ailanthus Webworm, Atteva aurea (Fitch), fig. 1—An oc-
casional pest of ailanthus, or tree of heaven, the olive-brown cat-
erpillar of this species feeds on the leaves under a thin web.
Sometimes it attacks the petioles, causing the leaves to wilt.
Control Measure 1 or 2 (end of circular).
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR
Fig. 1—Ailanthus webworm: larvae. The olive-brown larvae or worms
feed on the surfaces of leaves.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 5
Cynthia Moth, Samia cynthia (Drury).—The 3-inch, green
caterpillar of this species has black dots and blue tubercles on
its back. It feeds on the leaves of the tree of heaven. The adults
are handsome brown moths, each with a wingspread of 6 to 8
inches. Sometimes caterpillars of this kind defoliate the trees
on which they feed.
Control Measure 1 or 2 (end of circular) while small cater-
pillars are feeding.
ARBORVITAE
Bagworm, Thyridopteryx ephemeraeformis (Haw.), fig. 2.
—A widely distributed common pest, the larva of this species
feeds ravenously on both evergreen and deciduous trees and
Fig. 2. — Bagworm: cases or bags constructed by larvae. Some of the
bags shown here are almost filled with eggs laid by adult females of the
bagworm. Eggs that survive the winter hatch in early summer. The ap-
pearance of bags varies with the kinds of leaves from which the larvae have
made them.
shrubs. Usually evergreens defoliated by bagworms die. Some
of the spindle-shaped bags hanging from trees and shrubs dur-
ing the winter contain eggs that produce a crop of worms in the
following spring or summer. In southern Illinois, these eggs
hatch usually during the latter part of May, in central Illinois
during the first part of June, and in northern Illinois during the
latter part of June. Newly hatched larvae are easily overlooked.
After leaving the mother bag, a small larva feeds on nearby
foliage and begins to build a tough bag for itself with silken
6 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
thread and with bits of foliage taken from the host plant. Hence,
bags on maples, for example, look different from those on arbor-
vitae.
Each bag is enlarged to accommodate the rapidly growing
larva inside and is carried everywhere the larva goes. The larva
sticks its head out of the bag to feed, but quickly retreats when
disturbed by birds or other enemies. By late summer, when the
bag is 114 to 2 inches long, the larva matures, pupates, and
transforms to the adult stage. The adult male, a black, fuzzy
moth, emerges from its bag and flies about to mate with the
wingless female, which remains in the bag while she lays 500
or more eggs. After egg-laying, the female dies. The bagworm
produces only one generation a year in Illinois.
Fig. 3.—Red-headed ash borer: A, adults; B, larva or grub; C, adult
ready to emerge from its pupal case; D, furrows made by larvae in sapwood
and holes through which adults emerged.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES il
Because only the male adult flies, infestations of bagworms
are spread principally in the larval and egg stages. Small larvae
suspended by their silken threads may be carried by the wind
for considerable distances. Larger larvae often crawl from one
plant to another in search of food. Larvae or bags containing
eggs may be inadvertently transported by human beings.
Control Measure 1, 3, or 11 (end of circular) as soon as the
eggs hatch. Sprays applied in late summer after the larvae stop
feeding, or during the winter, are ineffective. The worm infes-
tation can be reduced by picking and burning the overwintering
bags.
Arborvitae Leaf Miner, Argyresthia thuiella (Pack.).—
Feeding by the leaf-mining caterpillar of this species on the in-
sides of needles causes the tips of arborvitae branches to turn
whitish, tan, and brown. Less than one-fourth inch long, each
greenish, red-tinged caterpillar comes from one of several eggs
deposited on the leaves by a small moth in the spring. This pest
may produce more than one generation in a season, and consid-
erable damage may result from its feeding.
Control Measure 2 (end of circular) when moths are flying.
The use of DDT may result in a build-up of mites.
Spruce Spider Mite.—See under Spruce. Control Measure 9
(end of circular).
Juniper Scale, fig. 28.—See under Juniper. Control Measure
3 (end of circular).
ASH
Red-Headed Ash Borer, Neoclytus acuminatus (F.), fig. 3.—
The short, white, round-headed grub of this species may girdle
small ash trees so severely that they break and fall. The grub
tunnels in many directions, mainly in the sapwood. The adults
are beetles, each about one-half inch long. Each has a reddish
head, which accounts for the common name, and a V-shaped yel-
low band across the wing covers. The female deposits eggs in
crevices of bark in early summer. The young larva bores into the
bark, where it feeds and grows until it pupates in late winter.
Control Measure 4 (end of circular).
Ash Borer, Podesesia syringae fraxini (Lug.), fig. 4.—This
insect was once considered to be the same as the lilac borer, but
it now appears to be different and to be limited to ash and moun-
8 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 4.—Ash borer: adult (museum specimen). The female adult, a
clear-winged moth, deposits eggs on the bark of a tree. Upon hatching, the
young borers penetrate the bark and bore into the wood.
tain ash. The adult, a moth with transparent rear wings, depos-
its eggs on the bark of the tree. The white larvae eat through
the bark, penetrating the harder wood to the center of some
branches. In the fall, when nearly full grown, and almost an inch
long, the borer works toward but not completely through the
bark. Here it digs a sort of cell in which it passes the winter.
Pupation occurs in the spring, and moths emerge in May and
June.
Control Measure 4 (end of circular).
Oystershell Scale, Lepidosaphes ulmi (1L.), fig. 5.—The oys-
tershell scale is inconspicuous, but it can be detected by careful
examination of the limbs and branches it infests. Each scale
protects itself by a light to dark brown oystershell-shaped cov-
ering about one-eighth inch long. It feeds by sucking plant sap
through a threadlike beak. Dense populations of this insect
cause severe damage to many kinds of trees and shrubs.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 9
Fig. 5.—Oystershell scale: an infestation on a twig. A sapsucking in-
sect is beneath each brownish shell. An infestation of this common and
destructive insect may kill twigs and branches of lilac and other plants.
The overwintering, pearly white eggs of the oystershell
scale hatch about the latter part of May, the time varying with
weather and latitude. Each young scale, called a crawler, moves
from beneath the mother shell and crawls about, usually toward
younger wood. After a short time the crawler settles, loses its
legs and antennae, and starts making a shell covering. The cov-
ering is enlarged from time to time to accommodate the grow-
ing insect. The male scale develops wings, escapes from the
shell by squeezing under the edge, and roams freely for a mate.
The female does not leave her shell for the mating event, but
keeps sucking away at the tree sap. Under her shell she lays
80 to 100 eggs, which hatch the following spring.
Control Measure 5 (end of circular) in late winter. Con-
trol Measure 3 about the first of June, after eggs hatch. Thor-
cugh spray coverage is essential.
Fall Webworm, Hyphantria cunea (Drury), fig. 6—Un-
sightly webs enclosing one or more branches of an ash in the
early fall are signs of a ravenous colony of hairy caterpillars of
the kind commonly known as the fall webworm. The adult fe-
male of the fall webworm, a satiny white moth, emerges from
one of the overwintering cocoons in early summer, mates, flies
into a suitable tree, and deposits a patch of several hundred
greenish eggs, usually on the under side of a leaf. On hatching,
the young caterpillars move as a group to the upper sides of
leaves and start feeding. At the same time, they start spinning
10 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
a web, which they enlarge to take in fresh foliage as needed.
They do not consume the leaves entirely but skeletonize them to
such an extent that they curl, dry up, and eventually die.
m: tent and damage. The tent or w ebbing contains
hairy caterpillars that feed on foliage of
Fig. 6.—Fall webwor
a colony of pale green, or yellow,
the host tree.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 11
Pale green or yellow in color, each with a dark stripe down
the back and a yellow stripe along each side, the caterpillars do
not leave the web until nearly full grown. At this time they
move in many directions and feed on almost any green foliage
available. When mature, they move to the ground to pupate
under sheltering debris or just below the surface of the soil.
Control Measure 1 or 6 (end of circular).
BIRCH
Bronze Birch Borer, Agrilus anxius Gory.—Widely distrib-
uted and a serious pest of birch trees in the open, especially
white birch, the three-fourths-inch long, white, flattened, and
footless grub of this species attacks all parts of the birch above
ground, burrowing under the bark and causing the bark to
loosen and separate from the wood. The slender bronze beetle
that develops from an overwintering grub cuts semicircular
holes through the bark and emerges in early spring. The female
lays white eggs in bark crevices. Larvae hatching from the eggs
penetrate the bark, feed, and grow to develop another genera-
tion.
Control Measure 4 (end of circular).
Birch Skeletonizer, Bucculatrix canadensisella Chamb.—
Unlike the bronze birch borer, which prefers trees in the open,
the larva of this insect prefers woodland trees for its periodic
attacks. Tiny caterpillars hatch from eggs placed singly on a
leaf by the very small female moth, which is seldom seen. Each
caterpillar bores directly into the leaf tissue, mines the leaf for
a few weeks, and then skeletonizes the leaf on the under side be-
fore dropping to the ground to pupate for the winter. The most
extensive damage by this insect is likely to occur in August.
Control Measure 1 or 2 (end of circular).
BOXELDER
Boxelder Bug, Leptocoris trivittatus (Say), fig. 7.—The
adult form of this species is a black and red bug that feeds
through a long, slender beak on the leaves and seed pods of the
boxelder tree. It does little damage to the tree, but it creates a
nuisance by congregating in great numbers about the tree and
by migrating to nearby dwellings in the fall in search of winter
12 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 7—Boxelder bug: adults. Shown here are boxelder bugs on the
foundation of a building. The bugs, which are black and red in color, are of
no consequence as pests of boxelder trees, but they are nuisances in and on
buildings.
quarters. Following hibernation, the female lays small red eggs
in bark crevices. The red-bodied, black-legged nymphs that
hatch from the eggs reach the adult stage through a series of
molts.
Control Measure 7 (end of circular).
Boxelder Aphid, Periphyllus negundinis (Thos.).—This is a
pale green, hairy plant louse that occasionally develops in great
numbers. An infestation by this aphid causes some injury to
the infested tree and creates a nuisance by covering sidewalks
and other objects beneath the tree with honeydew. Black eggs
are deposited by the female on branches in the fall. The eggs
hatch in the spring, and young aphids congregate on the new
buds, from which they withdraw plant juices through their slen-
der beaks. With the ability to develop several generations within
a few weeks, these aphids can soon become abundant.
Control Measure 3 (end of circular).
Eastern Tent Caterpillar, Malacosoma americanum (F.),
fig. 8—Although black cherry, chokecherry, and apple are
favorite hosts, ravenous caterpillars of this species in the
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 13
Fig. 8.
The female adult, a moth, lays a batch of eggs on a twig to produce a col-
ony of hairy caterpillars with black heads.
Eastern tent caterpillar: larvae and damage to boxelder foliage.
14 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
spring construct tents in a wide variety of trees, including box-
elder, elms, maples, and oaks. The black, hairy caterpillars
hatch in March from an overwintering mass of eggs plastered
to a twig in a brown band or collar. Caterpillars usually select a
fork of a branch for the construction of a tent. They leave the
tent to feed during the day but return at night. After feeding
for 5 or 6 weeks, each caterpillar spins a cocoon on a tree trunk
or in some other protected place, where it pupates. The adults,
reddish-brown moths, emerge in early summer. The female lays
a batch of eggs on a twig. This insect produces only one gen-
eration a year.
Control Measure 1 or 2 (end of circular). Although this
pest usually is kept under control by natural enemies, sprays
may occasionally be needed to prevent damage to valuable shade
trees.
BOXWOOD
Boxwood Leaf Miner, Monarthropalpus buxi (Lab.).—Dam-
age by this insect is indicated in early summer by small blotches
on the leaves of boxwood. Later the blotches enlarge to blisters
that cause the leaves to turn brown and to drop. The small yel-
lowish-green maggots or larvae of this species feed on the tissue
in the leaf during the summer and again in the spring before the
orange-yellow midges develop and emerge from the pupae. The
female deposits eggs in May for a new generation.
Control Measure 8 (end of circular) about May 15.
CATALPA
Catalpa Sphinx, Ceratomia catalpae (Bdv.), fig. 9—A rav-
enous feeder consuming great quantities of catalpa foliage, the
caterpillar of the sphinx moth may vary in color from pale yel-
low with green markings to almost black. The caterpillar. has
a black, hornlike process at its rear end. When grown, the cater-
pillar is about 3 inches long.
Emerging from an overwintering pupa in the soil, the fe-
male of this moth mates and lays hundreds of eggs in white
masses on the under sides of leaves. The young caterpillars
feed in groups at first, but work individually later, consuming
entire leaves.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES
: Fig. 9.—Catalpa sphinx: larvae on a catalpa leaf. The handsome cater-
pillars are ravenous feeders on catalpa foliage. About 3 inches long when
grown, each caterpillar has a black hornlike process at the rear end.
16 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Control Measure 1 or 2 (end of circular). Some people
grow catalpa trees mainly to raise caterpillars for fish bait, but
most tree lovers want to protect their trees from these cater-
pillars.
Comstock Mealybug, Pseuwdococcus comstocki (Kuw.).—An
occasional pest of catalpa, the Comstock mealybug is likely to be
found in cottony masses at the forks of tender shoots or at the
bases of leaves. The male, which has wings, is seldom seen. The
female, a wingless, slow-moving insect, when grown is about
one-fourth inch long and elliptical in shape; she has a fringe of
short, soft spines and is covered with ‘‘mealy,’ white wax. A
sucking insect like the aphid, the mealybug likewise secretes
honeydew, which supports a sooty mold.
The mealybug’s yellow eggs, found in crevices of bark, are
covered with a cottony mass of wax. When leaves appear on
catalpa trees in spring, the eggs hatch, and the young mealy-
bugs move to likely places to feed and grow. This insect may
produce several generations a year.
Control Measure 3 (end of circular) applied with force.
Fig. 10.—Yellow-necked caterpillar: larvae on small branch of haw-
thorn. When disturbed, these caterpillars rear up at both ends. Reddish
when young, each caterpillar has a black head and four yellow stripes along
each side of its body. A grown caterpillar is easily recognized by its yellow
neck and its black body, which is covered with long, white hairs.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 17
CRABS AND HAWTHORNS
Yellow-Necked Caterpillar, Datana ministra (Drury), fig.
10.—While seeming to prefer the foliage of apple and other fruit
trees, the larva of this species finds nothing distasteful about
the foliage of ornamental crabs and hawthorns wherever these
plants are grown. Reddish in color when young, the ugly, fuzzy
Fig. 11.—Woolly hawthorn aphid: infestation on hawthorn twig. The
aphids, which are white in color, have sucking mouthparts.
caterpillar has a yellow neck. It has a black head and four yel-
low stripes along each side of its body. Caterpillars of this spe-
cies feed ravenously in groups, but, when disturbed, they stop
feeding and rear up at both ends. When fully grown, each cat-
erpillar drops to the ground, burrows in a short way, and pu-
pates. The adults, or moths, appear in early summer, and at
about this time the female deposits eggs in clusters on the
under sides of leaves.
Control Measure 1 or 2 (end of circular) when caterpillars
are small.
Woolly Hawthorn Aphid, Eriosoma crataegi (Oest.), fig. 11.
—Occurring in dense colonies on twigs and branches, the white,
restless plant lice of this species are conspicuous. They may
18 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
cause considerable damage to the hawthorn, distorting leaves
and shoots by their removal of plant juices. The life history of
this aphid is probably a complicated one and is not well known.
Control Measure 3 (end of circular) applied with force.
European Red Mite, Metatetranychus ulmi (Koch) .—Leaves
of hawthorn or crab lacking a glossy, green appearance and hav-
ing a somewhat blanched, or brown, dry look and a tendency to
curl are signs of damage produced by hundreds of tiny red mites
of this species feeding on both leaf surfaces. Brick red in color,
the adults of the European red mite are scarcely the size of pin-
heads. They have bristle-like hairs curving backward over their
robust, globular bodies. The female deposits her eggs, which
look like tiny cherries, in great numbers on both leaf surfaces.
Development of the mite occurs through a series of molts. The
white, discarded molt skins of a great number of young mites
make infestations conspicuous. Rasping of the leaf surfaces
and withdrawal of chlorophyll and plant juices cause serious
damage to the plants infested.
Control Measure 9 (end of circular).
San Jose Scale, Aspidiotus perniciosus Comst., fig. 12.—
Probably the best known of the scale insects, San Jose scale is
widely distributed and is a serious pest on many trees and
shrubs. Heavy infestations encrust limbs and branches, causing
them to die. Scraping an infested branch with a thumb nail or a
knife squeezes the yellow juice from the saclike insects beneath
the gray to black, circular shells, each about one-sixteenth inch
Fig. 12.—San Jose scale: infestation on bark of tree. A yellow saclike
insect is beneath each circular shell shown here. The shells are each about
one-sixteenth inch in diameter and gray to black in color.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 19
in diameter. The female overwinters as a partly grown insect
and reaches maturity in early spring. After mating, she gives
birth to living young: small, flat, yellow creatures, which crawl
out from under the mother shell. When a crawler finds a suitable
place, it settles down, inserts its threadlike beak into the bark
tissue, loses its legs and antennae, and starts making a shell for
its own protection. As the scale grows, its shell is enlarged and,
following a series of molts, the scale reaches maturity. The
fragile male scale develops wings and escapes from its protective
shell to mate with a female, which does not leave its shell. The
San Jose scale may produce several generations in a summer.
Control Measure 5 (end of circular) on dormant plants.
Fig. 13.— Hawthorn leaf miner: larva and damage to hawthorn leaf.
The upper epidermis along one margin of the leaf is folded back to dis-
close the white larva (arrow) and its excrement. Along the opposite mar-
gin of the leaf is a dark blister, a sign of damage by the leaf miner.
20 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Hawthorn Leaf Miner, Profenusa canadensis (Marlatt), fig.
13.—Conspicuous dead areas that may include a fourth to half of
a leaf at the tip or side indicate damage by the leaf miner. The
adult is a sawfly, a beelike insect, that emerges from an over-
wintering pupal case in the soil and deposits eggs in the tissue of
unfolding leaves in May. The eggs, which may number 1 to 5 per
leaf, produce larvae that mine the leaves. About 2 weeks after
hatching, each larva makes a hole in the leaf and drops to the
ground, where pupation and hibernation occur. This insect pro-
duces one generation a year.
Control Measure 10 (end of circular) just as soon as the
leaves are fully expanded. Spray applications earlier or later are
ineffective.
DOGWOOD
Dogwood Borer, Thamnosphecia scitula (Harr.).—The cat-
erpillar of this species is white and it has a brown head. It is the
larva of a clear-winged moth with a wingspread of less than an
inch. Eggs deposited by the female moth on the bark of dogwood
trees in May and June produce borers that eat through the bark.
These borers feed just beneath the bark, often girdling limbs
and small trees. The borers become full grown before winter,
hibernate in their tunnels, and change to pupae in the spring.
Control Measure 4 (end of circular).
Dogwood Scale, Chionaspis corni Cooley.—Usually kept un-
der control by natural enemies, this scale occasionally builds up
dense populations that give twigs and branches a whitish appear-
ance. The female scale is somewhat pear shaped and about one-
eighth inch long; the male scale is smaller and more slender and
has three ridges on the upper side. Purple eggs carry the insect
through the winter.
Control Measure 5 (end of circular) in late winter or Con-
trol Measure 2 in early summer after the eggs have hatched.
DOUGLAS FIR
Cooley Spruce Gall Aphid, Chermes cooleyi Gill., fig. 14.—
Douglas fir is the intermediate host for this small aphid, which
splotches the needles with cottony masses of wax that protect
the aphid and her eggs. Some of the aphids developing from
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 21
Fig. 14.—Cooley spruce gall aphid: an infestation on Douglas fir. Each
white splotch on the needles represents a cottony mass of wax that protects
an aphid. Beneath the wax the female lays her eggs. Some of the insects
developing from these eggs have wings; others do not. Those that have
wings migrate to spruce, where they produce galls at the tips of branches.
these eggs have wings and they migrate to spruce, where they
produce galls. No galls develop on Douglas fir.
Control Measure 3 (end of circular) in June.
ELM
Spring Cankerworm, Paleacrita vernata (Peck), figs. 15 and
16.—The spring cankerworm is a common pest of elms and per-
haps the most important leaf eater that infests the American
elm in Illinois. The caterpillar, or larva, is a dark green or black
“measuring worm” that does not wait for the buds to unfold be-
fore starting to feed. At first rather inconspicuous, the small
caterpillar eats the tissue on one side of any leaf it feeds upon,
but as it grows it punctures and later consumes all of the leaf
except the large veins. By the time the caterpillar is 1 inch long,
or full grown, it may be red, green, yellow, or black in color.
It drops to the ground by means of a thread, burrows into the
soil, and pupates. The adults emerge during warm spells in late
22 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
winter. The wingless female climbs a nearby tree and, after mat-
ing, hides hundreds of eggs in crevices and under loose bark.
These eggs hatch just as soon as the leaf buds begin to open in
the spring. An elm may be partly or completely stripped of its
foliage by spring cankerworms.
Control Measure 1 or 2 (end of circular) as soon as leaf buds
begin to open in spring, when the worms are still small.
Fig. 15.—Elm foliage damaged by spring cankerworms. The dark green
to black “measuring worms” begin feeding before leaf buds are completely
open.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 7c"
White-Marked Tussock Moth, Hemerocampa leucostigma
(J. E. Smith), fig. 17—Second in importance to the spring can-
kerworm as a leaf eater of American elm, this insect in its larval
stage is mainly a pest of city shade trees. The showy caterpillar
of the tussock moth begins feeding a little later in the spring
than the cankerworm but may develop two generations in a
year to make up for the late start. Its body is covered with tufts
Fig. 16.—Spring cankerworm: A, male adult; B, female adults (wing-
less); C, eggs; D, larva; E, pupae. The larva is dark green, brown, or
black. (Photographs from United States Department of Agriculture.)
of long white hairs. Two longer tufts of black hairs provide
“horns” at the front, while a single black tuft ‘flags’ the rear.
When 5 or 6 weeks old, the caterpillar stops consuming leaves
and spins a cocoon on the trunk or a limb of the tree on which it
has been feeding, or on a fence or house. Here transformation
takes place. From the cocoons emerge winged males and wing-
less females. A wingless female, after emerging and mating,
lays several hundred white eggs, all glued together in a clump,
24 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 17.—White-marked tussock moth: caterpillar, or larva, on leaf.
This caterpillar is hairy; it has a red head, and its body is strikingly colored
with yellow, black, red, and white.
on the empty cocoon. Newly hatched caterpillars skeletonize the
leaves and consume all but the large veins.
Control Measure 1 or 2 (end of circular). Obviously, sprays
applied while the insect is in the cocoon and egg stages are in-
effective.
Fall Webworm, fig. 6.—See under Ash. Control Measure
1 or 6 (end of circular).
Elm Leaf Beetle, Galerucella xanthomelaena (Schr.), fig.
18.—Another ravenous leaf eater and a particular pest of Chi-
nese elm, the larva or grub of the elm leaf beetle skeletonizes
the leaves, causing them to dry out, curl, and drop prematurely.
An ugly, almost black, spiny grub hatches from each of the yel-
low, spindle-shaped eggs placed by the female beetle in small
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 25
Fig. 18.—Elm leaf beetle: A, eggs; B, larva; C, pupa; D, adult. Both
larva and adult feed on foliage. The eggs are yellow and spindle shaped; the
larva is spiny and almost black; the adult, about one-fourth inch long, has
a yellowish to green body and yellowish legs and antennae.
groups on the under sides of the leaves of an elm tree about the
time the leaves become full grown. When through feeding, the
grub drops or crawls to the ground near the base of the tree,
pupates, and transforms to the adult stage to start another gen-
eration. The adults hibernate in barns, sheds, and dwellings,
where, if present in large numbers, they sometimes become a
Fig. 19.—European elm scale: an infestation on an elm twig in spring.
Each seale has a reddish center and a white fringe.
26 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
nuisance. Each beetle is about one-fourth inch long; it has yel-
lowish legs and antennae and a yellowish to green body. It
chews small holes in the foliage. The female beetle lays 400 to
800 eggs, which hatch in about a week.
Control Measure 1 or 2 (end of circular) about the time
leaves are grown or as soon as damage is observed.
European Elm Scale, Gossyparia spuria (Mod.), fig. 19.—
Although inconspicuous, like other scale insects, the European
elm scale occurs in dense populations and sucks great quantities
of sap from any tree it infests. Some of the sap is secreted as
honeydew, on which a sooty mold may grow.
The immature scale, which overwinters on a limb or branch
or in a crotch of an elm, is about one-tenth inch long, oval, red-
dish-brown in color, and has a white fringe. The male completes
development in a white cocoon. The female changes little from
the overwintering form. In early summer, she lays eggs on a
limb or branch. Hatching in an hour or so, the young scales
move in great numbers to the under sides of nearby leaves,
where they settle and feed until late summer. Many migrate
back to a limb or branch to hibernate, but some are lost when
the leaves drop in autumn.
Control Measure 5 (end of circular) in late winter or Con-
trol Measure 3 in June.
Scurfy Scale, Chionaspis furfura (Fitch), fig. 20.—Widely
distributed and a pest of fruit and shade trees in addition to elm,
the dirty white, pear-shaped scale of this species is about one-
eighth inch long. Infestations of this scale are more conspicuous
than the infestations of some other scales, especially when they
are dense enough to give the infested bark an ugly appearance.
Withdrawal of sap from a tree by an infestation of this scale
reduces the vitality of the tree, kills branches and limbs, and
sometimes, if the tree is young, deforms it.
The purple eggs, which carry the insect through the winter,
begin hatching toward the last of May, giving rise to tiny purple
crawlers that move away from the mother’s shell. The crawlers
soon settle on the bark to feed and to make shells of their own.
The scale covering of the female is broad, while that of the male
is narrow and has three longitudinal ridges. This scale may
produce two generations a year in the southern half of Illinois,
but usually it produces only one generation a year in the northern
half of the state.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 27
Fig. 20.—Scurfy scale: an infestation on an elm twig. The scales are
gray and somewhat pear shaped. The overwintering eggs under the shells
are purplish. The hole made in one scale by an emerging parasite is indi-
cated by an arrow.
Fig. 21.—Putnam scale: an infestation on an elm twig. The covering
or shell of the female scale is almost circular and about one-sixteenth inch
in diameter; that of the male is oblong. Near the center of each shell is a
brick-red nipple that contrasts with the dark gray or black remainder of
the shell. The scale insect beneath the shell is yellow.
28 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Control Measure 5 (end of circular) applied in late winter, or
Control Measure 3 applied after eggs have hatched and while
scales are still small.
Putnam Scale, Aspidiotus ancylus (Putn.), fig. 21.—Ordi-
narily of little consequence, but a pest that may do serious dam-
age to elms following repeated foliar applications of DDT, Put-
nam scale sometimes encrusts limbs and branches, causing them
to die. Only about one-sixteenth inch in diameter, the female
scale covering is almost circular and is cemented to the bark
as a shell resembling an inverted saucer with a brick-red nipple
that contrasts with the dark gray or black remainder of the shell.
The shell of the male of the Putnam scale is oblong in shape.
Fig. 22.—Elm leaf aphid: infestation on under side of elm leaf. The
aphids are greenish and of various sizes; some have wings and some are
wingless.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 29
The insect passes the winter as a yellow, partly grown scale
beneath the shell. Development is completed in early spring, and,
after mating, the female lays a few eggs a day. Egg laying and
hatching extend over a period of 6 weeks or more. Some of the
first-brood crawlers settle on the leaves of the elm, where de-
velopment is completed; the second brood crawlers migrate back
to the limbs or branches for the winter.
Control Measure 5 (end of circular).
Elm Leaf Aphid, Myzocallis ulmifolii (Monell), fig. 22.—
For the most part, this aphid is a nuisance pest because of the
honeydew that drips on sidewalks and automobiles from the elm
leaves on which the aphid feeds. Following repeated foliar appli-
cations of DDT to elm trees, infestations of this aphid increase,
the secretion of honeydew increases, and some damage to in-
fested trees undoubtedly results. Except for sooty mold that
grows in the honeydew, there is no visible evidence of damage.
Both winged and wingless forms of the yellowish-green
aphid, as well as white molt skins, are usually present on the
under sides of elm leaves. Unlike many species of aphids, the elm
leaf aphid does not migrate to another host.
Control Measure 3 (end of circular).
Woolly Elm Aphid, Eriosoma americanum Riley.—Curled
elm leaves are signs of an infestation on the under sides of the
leaves by the white, woolly, restless aphids of this species. In-
festations are localized rather than general. This species over-
winters in the egg stage. Eggs laid on bark hatch about the
time elm leaves unfold; upon hatching, the aphids crawl] to the
leaves and begin to suck juices from the tissues. In June, the
winged form migrates to shadbush, where it gives birth to a
wingless form which, in time, produces another winged form
that migrates back to elm to lay the overwintering eggs.
Control Measure 3 (end of circular).
Elm Cockscomb Gall Aphid, Colopha ulmicola (Fitch), fig.
23.—On an elm leaf, a conspicuous, unsightly growth resembling
a cock’s comb is a sign of this aphid. Production of each gall is
stimulated by a wingless female aphid to provide a home for her
family.
Control. Galls produced by aphids of this species do little
damage. No control measure is recommended.
Elm Borer, Saperda tridentata Oliv., fig. 24.—Escaping sap
and small masses of wet, brown frass on the trunks and limbs of
30 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 23.—Elm cockscomb galls. Each gall contains many greenish aphids.
elms indicate the presence of larvae of this species. Probing an
infested tree with a knife will disclose flat, shallow galleries run-
ning in many directions and white, legless, segmented grubs.
Each larva is about an inch long when full grown. The larva pu-
pates in May. The adult is a gray beetle, about one-half inch
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 31
long, with three orange-colored stripes across each wing cover.
The beetle cuts through the bark to escape. After mating, the
female beetle deposits eggs on the bark of an elm tree. The
young grubs that hatch from the eggs bore into the bark.
Control Measure 4 (end of circular).
Smaller European Elm Bark Beetle, Scolytus multistriatus
(Marsh.), fig. 25.—This bark beetle is the more important of two
Fig. 24.—Elm borer: A, larva; B, pupa; C, adult. The larva, or grub,
is white and legless. The adult is a gray beetle about one-half inch long
that has three orange-colored stripes on each wing cover (stripes only
faintly visible in picture).
species that spread the deadly Dutch elm disease in Illinois. The
other is the native elm bark beetle, Hylurgopinus rufipes
(Eichh.), which is rarely found in Illinois.
The white, legless grub, or larva, of this beetle passes the
winter under the bark of an elm tree. It pupates in early spring
and transforms to the adult, a reddish-brown beetle, which drills
a small hole through the bark to escape. Thousands of ‘shot
holes’”’ characterize the bark of heavily infested trees. If the
beetle emerges from a tree infected with Dutch elm disease, it
may carry spores of the disease fungus to a healthy tree, where
inoculation takes place when the beetle feeds in the crotches of
small branches. After feeding in the crotches of living elms, the
beetle bores into recently cut elm wood or weak and dying tree
trunks or branches. The female places white, spherical eggs
along the edges of a gallery she constructs for this purpose.
Small, white larvae that hatch from the eggs feed between the
bark and wood, producing characteristic patterns with their
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
bark beetle: larvae and galleries on the
Fig. 25.—Smaller European elm
etles, carry the Dutch
under side of elm bark. The adults, small, brown be
elm disease fungus from diseased to healthy elms.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 33
mines. Emergence of beetles begins about the middle of May in
Illinois and reaches a peak about the middle of June. A second
brood of beetles which follows reaches a peak emergence in
August.
Control Measure 18 (end of circular).
Banded Elm Leafhopper, Scaphoideus luteolus Van D.—
Rarely seen, this brown leafhopper, narrow and about one-fourth
inch long, is reported to be the carrier of phloem necrosis, a seri-
ous virus disease of American elms. The eggs of this insect over-
winter on the bark of elms and hatch in early spring; the young
hoppers, called nymphs, feed on new foliage, producing a brown
area where the sap is withdrawn. The leafhoppers themselves
cause little direct damage, but the virus they carry from diseased
to healthy American elms is deadly to the trees.
Control Measure 18 (end of circular). Spraying trees with
DDT will reduce the number of leafhoppers and check the spread
of phloem necrosis, but mite infestations may follow.
Mites.—Several species of mites infest elms, but usually the
damage they do is of little consequence. However, following the
repeated use of DDT on elm foliage, infestations of the two-spot-
ted spider mite, Tetranychus telarius (L.), fig. 483, may become
dense enough to bronze the leaves and reduce the vitality of
trees.
Control Measure 9 (end of circular).
EVONYMUS
Euonymus Scale, Unaspis evonymi (Comst.), fig. 26.—This
most important and destructive pest of euonymus is common
also on bittersweet and pachysandra. The great number of white
coverings of the males on the under sides of the leaves of in-
fested plants immediately attracts attention and serves to help
identify the pest. The female lives under a gray or brown shell,
shaped somewhat like the shell of an oyster. In spring, the over-
wintering female lays orange-yellow eggs, which produce
crawlers that leave the mother shell and find a place to settle and
grow on the host plant. This scale produces at least two genera-
tions a year.
Control Measure 3 (end of circular) about July 1 when
hatching of eggs is complete. The spray should be repeated early
in September.
34
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
infestations on leaf, A, and twigs, B and C,
are males, each of which has a white
Euonymus scale:
of euonymus. Most of the scales shown
covering. The dark scales on twig B are females.
Fig. 26.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 3D
HACKBERRY
Hackberry Nipple Gall Psyllid, Pachypsylla celtidis-mamma
(Flet.)—Conspicuous growths on the upper sides of hackberry
leaves are signs of an infestation of this insect, sometimes called
P A
-
oid } Bia he 9 ad
te te i ‘
KPO SN
Fig. 27.—Witches’-brooms on a hackberry tree. The brooms are very
conspicuous in winter, when no leaves are on the tree.
36 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
a jumping plant louse. Formation of each gall is stimulated by
a tiny insect that feeds and lives inside the gall. The small, yel-
lowish-brown adults pass the winter in bark crevices of trees or
in the debris under trees. About the time leaf buds unfold, the
female deposits eggs on the under sides of leaves. When the
eggs hatch, each young insect crawls to the upper side of a leaf,
settles down, and begins to feed through a short beak. The leaf
tissue grows around the insect in characteristic fashion to form
a gall. By September the insect completes its development and
emerges as an adult through a slit it makes in the base of the
gall. At that time of year, insects of this species may make
nuisances of themselves by flying into houses.
Control Measure § (end of circular) applied to trees about
the time the leaves begin to unfold.
Witches’-Broom, fig. 27.—Abnormal growth that results in
bunches or tufts of small twigs on the limbs and branches of
hackberry is commonly called witches’-broom. Apparently the
brooms do little harm to an affected tree, but they detract from
its appearance. A tiny mite, Aceria snetsingert Keifer, and a
fungus, Sphaerotheca phyloptophila Kell. & Swingle, are asso-
ciated with witches’-broom, but it is not known whether either
or both stimulate the peculiar growth.
Control. No. satisfactory measure for the control of
witches’-broom on hackberry has been developed.
HICKORY
Yellow-Necked Caterpillar, fig. 10.—See under Crabs and
Hawthorns. Control Measure 1 or 2 (end of circular).
Hickory Bark Beetle, Scolytus quadrispinosus Say.—Small
emergence holes in the bark of the trunk and branches of a hick-
ory tree are signs of an infestation by this species. The adults
are dark brown beetles, each less than one-fourth inch long.
After emerging from beneath the bark, each beetle feeds for a
short time on young twigs, then bores through the bark of the
same or a different tree, and constructs a gallery between the
bark and the wood. Along the edges of the gallery, the female
deposits eggs that give rise to white, legless grubs, which cause
further and more extensive damage.
Control Measure. This species is especially injurious to
hickories growing in parks. Heavily infested trees should be
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 37
cut down during the winter to destroy overwintering grubs.
Healthy trees should be kept in a vigorous condition with appli-
cations of water and fertilizer.
Hickory Gall Phylloxera, Phylloxera caryaecaulis Fitch.—
Often overlooked until the affected twigs have died and the
globular galls have been abandoned and have turned black, the
greenish insects of this species may cause considerable or little
injury to hickories, depending on the degree of infestation.
After hatching from overwintering eggs, the young aphids
stimulate the growth of galls on new twigs and prevent normal
growth or kill the twigs beyond the galls. Each gall, which is at
first green and may be one-half to three-fourths inch in di-
ameter, is crowded on the inside with the greenish plant lice.
Control Measure 5 (end of circular) in winter or Control
Measure 8 about the time buds unfold.
Hickory Horned Devil or Regal Moth, Citheronia regalis
(F.).—The larval form of this insect is an occasional leaf eater
of hickory as weil as several other trees. It looks enough like the
devil to be frightening. Approximately 5 inches long, this larg-
est of our native caterpillars has a green body, a red head, and
curving red horns just back of the head. In contrast, the adult
insects are beautiful olive-green moths with a wing expanse of
4 to 6 inches.
Control Measure. Although a ravenous feeder, the hickory
horned devil does not occur in sufficient numbers to justify spray-
ing. Caterpillars on small trees can be collected and destroyed
by hand.
JUNIPER
Juniper Scale, Diaspis carueli Targ., fig. 28.—This pest is
common on various kinds of junipers, especially on plants used
for landscaping. The covering of the female scale is nearly cir-
cular and is dirty white in color. The covering of the male scale
is white; it has a median ridge and is narrower and smaller than
that of the female. Juniper scale may develop into a dense popu-
lation on twigs and branches of junipers, causing them, or even
entire plants, to die. In May, the overwintering female deposits
eggs, which hatch in June.
Control Measure 2 (end of circular) about July 1, after eggs
hatch.
38 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Juniper Webworm, Dichomeris marginella (F.), fig. 29.—
The larva of this species is a light brown caterpillar only about
one-half inch long. Several caterpillars web together and feed on
juniper foliage, causing it to turn brown and die. Development
of the caterpillars is completed in early summer. Pupation occurs
Fig. 28.—Juniper scale: an infestation on juniper. Dark red, sapsucking
scale insects are under the gray or white shells on the surfaces of twigs.
in the webbing and debris; from each pupa a moth emerges. The
female deposits eggs on foliage to produce another brood of cat-
erpillars that pass through the winter. The caterpillars become
active again in the spring.
Control Measure 1 or 2 (end of circular) as soon as the cat-
erpillars are discovered. Spray should be applied forcefully.
Juniper Bark Beetle, Phloeosinus dentatus Say.—Several
kinds of junipers are damaged by the adults of this species, dark
brown, tubular beetles, each about one-sixteenth inch long. Be-
ginning in early spring, the beetles feed in the crotches of small
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 39
branches, weakening many of them so that they bend down,
break, and die.
Control Measure 13 (end of circular) at monthly intervals
during the spring and summer, beginning about April 15. If
mites develop, Control Measure 9 also should be used.
Spruce Spider Mite.—See under Spruce. Control Measure
9 (end of circular).
Bagworm, fig. 2.—See under Arborvitae. Control Measure
1, 3, or 11 (end of circular) in June, while worms are small.
Fig. 29.—Juniper webworm: larva (inset) and web on damaged branch.
A colony of the small, brown caterpillars of this insect usually kills an in-
fested branch.
40 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
LILAC
Lilac Borer, Podosesia syringae syringae (Harr.), fig. 30.—
The larva of this insect is a major pest of lilac. The adults are
moths that have transparent rear wings. Holes made in the bark
of lilac by the grubs are likely to be numerous and are charac-
terized by protruding sawdust, oozing sap, and, in the spring, by
brown pupal cases at the entrances of emergence holes. Eggs
deposited by the female in early summer on rough bark give rise
to the white grubs that bore through the bark into the wood be-
neath, where they feed and grow until winter brings their activi-
ties to a halt.
Control Measure 4 (end of circular).
Oystershell Scale, fig. 5—This is a major pest of lilac. See
under Ash. Control Measure 5 (end of circular) in late winter
or Control Measure 3 in early summer.
LINDEN
Elm Spanworm, Hnnomos subsignarius (Hbn.).—The adult
form of this species is sometimes called the snow-white linden
moth. Both male and female are pure white. The larva or cater-
pillar is a gray and brown looper with irregular yellow marks.
Outbreaks of this insect occur at intervals of 10 to 20 years. The
female moth deposits eggs in the summer on tree branches. The
eggs do not hatch until the next spring. When outbreaks occur,
the caterpillars are present in such numbers that they defoliate
linden and several other kinds of trees.
Control Measure 1 or 2 (end of circular).
LOCUST
Locust Borer, Megacyllene robiniae (Forst.), fig. 31—Black
locust is particularly susceptible to the larva of this insect. The
larva is white, cylindrical, and up to 1 inch long. At first it mines
the bark and sapwood of the locust, but later it bores into the
heart of the tree, often causing so much damage that the trunk
breaks. Growth, pupation, and transformation of the insect take
place in the wood. The adults are beetles that emerge in autumn
and feed on the pollen of goldenrod. Each is about three-fourths
inch long, black, and has zig-zag yellow lines across the back.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 41
Fig. 30.—Lilac borer: A, damage to lilac branch; B, adult, a clear-
winged moth, on twig with frass at exit holes; C, larva in lilac branch (cross
section). (Photographs A and B from Connecticut Agricultural Experi-
ment Station.)
42 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
\t
Fig. 31.—Locust borer: A, eggs in crevices of limb: B, adult, mostly
black but with yellow markings; C, larva in its burrow in trunk of young
locust; D, young locust tree broken over by wind after damage by locust
borer. (Photographs from Ohio Agricultural Experiment Station.)
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 43
The female deposits eggs in the cracks and crevices of locust
bark.
Control Measure 4 (end of circular) for protection of young
trees. Honey locust, which is not readily attacked, should be used
for shade in place of black locust.
Bagworm, fig. 2—This pest occurs on both black locust and
honey locust. See under Arborvitae. Control Measure 1, 3, or 11
(end of circular) in June, while worms are small.
Locust Mite, Hotetranychus multidigituli (Ewing).— This
mite, somewhat similar to other species of mites found on trees
and shrubs, seems to be peculiar to honey locust. Just large
enough to be visible to the naked eye, the mite varies in color
from pale yellow to green; it has irregular dark areas near the
edge of the body. The female deposits colorless spheroid eggs
along the midrib of the under side of a leaflet. The base of the
leaflet on the under side is the preferred feeding area. At first,
heavily infested foliage appears stippled from above, but later it
becomes blanched, and leaflets drop prematurely.
Control Measure 9 (end of circular) when mites occur.
Mimosa Webworm, Homadaula albizziae Clarke.—This pest,
relatively new in Illinois, has been observed in the Washington,
D. C., area on mimosa since 1940 and on honey locust since 1943.
Damage to the foliage of these trees may be extensive.
The adults, mouse-gray moths, each with a wing expanse of
only about one-half inch, emerge from overwintering pupae early
in June. The female deposits eggs on the leaves of honey locust
or mimosa. The small, pale gray to brown larvae web the leaves
together to form a sort of nest, in which they skeletonize the
leaflets. Badly damaged leaflets become dry and brown. In Illi-
nois, such symptoms of webworm attack may appear by the
latter part of July. When grown, each larva drops to the ground
on a silken thread to pupate under ground cover. Second brood
larvae produce conspicuous webbing in August. In the Wash-
ington, D. C., area, the mimosa webworm produces a partial third
generation each year.
Control Measure 1 or 2 (end of circular).
MAPLE
Cottony Maple Scale, Pulvinaria innumerabilis (Rathv.),
fig. 32.—A common, conspicuous, and injurious pest of soft ma-
44 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
ple, this species is found on several kinds of maples and a variety
of other trees and shrubs. The infestations may be heavy enough
to kill twigs, branches, limbs, and, occasionally, entire trees.
The scale insects secrete great quantities of honeydew that drips
Fig. 32.—Cottony maple scale: infestation on soft maple. An infesta-
tion of this insect can be identified easily by the masses of white wax, each
of which contains hundreds of eggs.
on branches and foliage of infested trees, and on sidewalks and
automobiles below. A sooty mold that sometimes grows in the
honeydew causes branches and foliage to appear black.
The partly grown, brown, oval, female scale overwinters on
a twig or branch. She grows rapidly in the spring and lays hun-
dreds of eggs in a mass of cottony threads. Heavily infested
branches appear as if decorated with popcorn. When the eggs
hatch in June or July, young scales migrate to the leaves, where
they settle and suck food from the leaf tissue. The males and
females become mature in August; after mating, each female
crawls back to a twig for the winter.
Control Measure 5 (end of circular) late in the winter or
Control Measure 3 in summer. Fortunately, cottony maple scale
has many natural enemies which help control it. However, at
times sprays may be needed.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 45
Maple Bladder-Gall Mite, Vasates quadripedes (Shimer), fig.
33.—Unsightly green and reddish growths (galls) on the upper
sides of the leaves of soft maple are signs of an infestation of the
extremely small mites of this species. The mites overwinter on
the bark of trees and in spring migrate to young leaves, where
they stimulate the formation of galls, in each of which many
mites live and feed. It is doubtful if galls associated with this
species cause enough damage to large, vigorous trees to justify
Fig. 33.— Maple bladder galls on the upper side of a soft maple leaf.
Growth of each gall is stimulated by extremely small mites, which live in
the gall. This mite apparently causes little damage, except possibly to
small trees. (Photograph from Michigan State University.)
46 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
spraying. Small trees, struggling for a start, may be benefited by
spraying.
Control Measure 3 (end of circular) after buds are swollen
but before new leaves appear in spring. Sprays applied after
galls develop are useless.
Green-Striped Mapleworm, Anisota rubicunda (F.).—An oc-
casional pest of maple, the caterpillar of this species consumes
entire leaves, and an infestation may defoliate a tree within a
short time. The full-grown caterpillar is about 2 inches long. It
is yellowish-green in color, has green stripes running lengthwise
on its back, spines on its sides, and two horns on its thorax. The
adults or moths of this species emerge in early spring from pupae
in the soil; the female lays eggs on leaves of maples. The insect
may produce two generations in a year.
Control Measure 1 or 2 (end of circular) as soon as an infes-
tation is discovered.
Flatheaded Apple Tree Borer, Chrysobothris femorata
(Oliv.), fig. 84. — The larva of this common and widely distrib-
uted insect attacks a great variety of shade trees and fruit trees.
Fig. 34. — Flatheaded apple tree borer: A, larva; B, adult, a gray or
brown metallic-colored beetle about one-half inch long. (Photographs from
United States Department of Agriculture.)
Almost any tree that is weakened by transplanting or dry weather
or is wounded or damaged by sunscald may be invaded by this
destructive borer. The adults are flat, metallic-colored beetles,
each about one-half inch long. The female lays eggs in cracks
and crevices in the bark of a tree; the young borers that emerge
from these eggs have little trouble in boring through and tun-
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 47
neling under the bark. Often, trees are girdied by the white, leg-
less, slender grubs with big flat heads. Feeding mainly in the
sapwood at first, each grub mines deeper as it becomes larger
and when grown it makes enough room at the end of a tunnel to
spend the winter. Pupation and transformation take place in the
early spring. At this time, an adult emerges through the tunnel
made by a borer. The life cycle of the flatheaded apple tree borer
is completed in a year.
Control Measure 4 (end of circular).
Aphids.—Two species of aphids are pests of maples. They
suck sap from the under sides of maple leaves and secrete enough
honeydew, at times, to wet the sidewalks and streets under the
trees. The Norway-maple aphid, Periphyllus lyropictus (Kess.),
is a greenish insect that feeds along the veins on the under sides
of the leaves of Norway maple and hard maple. The painted
maple aphid, Drepanaphis acerifoliae (Thos.), is gray or black
in the winged form and yellow in the wingless form. It is more
common on soft maple than on other maples.
Control Measure 3 (end of circular) if damage is apparent
and if the nuisance caused by the aphids is insufferable. Aphids
usually do not cause enough damage to large trees to justify the
expense of spraying.
Pigeon Tremex, Tremex columba (L.).—Associated with
diseased and dying maples and many other kinds of trees, the
pigeon tremex may be erroneously blamed as a serious tree pest.
Each almost 2 inches long and with a reddish head and thorax,
the adults are wasplike sawflies that bore holes in the trunk of a
tree; there the female deposits eggs which hatch into grubs that
live in the infested tree until development and transformation
are completed.
Control. A slender parasitic wasp belonging to the great
family of parasites, the Ichneumonidae, probably does more to
control the pigeon tremex than could be done with all sorts of in-
secticides. With her ovipositor, a long threadlike appendage at
the end of her abdomen, the female of this wasp, with uncanny
precision, drills into a tremex tunnel and deposits an egg which
produces a larva that attaches itself to the tremex grub and
kills it.
No insecticide treatment is recommended for the pigeon
tremex. Trees infested by the tremex probably should be cut
down and removed because they are dying from other causes.
48 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
OAK
Borers.—Like other trees when weakened by transplanting
shock, dry weather, or poor environment, oaks may be attacked
by several species of borers. The flatheaded apple tree borer
(see under Maple) and the carpenterworm (see under Poplar)
are common pests of oaks.
Control Measure 4 (end of circular).
Periodical Cicada, Magicicada septendecim (L.), fig. 35.—
The female of the periodical cicada, which seems to prefer the
terminal twigs of oaks for laying eggs, causes damage by tearing
the bark and wood where she thrusts eggs into a twig. The dam-
age resulting from many egg deposits in a twig causes it to die,
and possibly to break off. Tiny nymphs hatch from the eggs,
drop to the ground, burrow into the soil, and subsist for a 13- or
17-year period on the plant juices they can obtain from roots.
The nymphs emerge from the ground in early summer, attach
themselves to nearby objects, and molt to become adults. Both
male and female are black and robust; they have reddish eyes,
legs, and wing veins. With strident song, the males announce the
presence of cicadas in great swarms at intervals of 13 or 17
years.
Control Measure 19 (end of circular).
May Beetles, Phyllophaga spp.—The adults of many species
of Phyllophaga (May beetles or June bugs) feed on the foliage
of oaks and other trees, sometimes in such numbers that they
defoliate small trees. These adults, which feed at night, are at-
tracted to lights. Most of the beetles are solid brown in color and
are one-half to three-fourths inch long. Eggs deposited by the
female in the soil produce larvae, white grubs, that feed on the
roots of grasses and other plants. Most May beetles have a
3-year life cycle.
Control Measure 1 or 2 (end of circular) when beetles are
feeding.
Twig Pruner, Hypermallus villosus (F.).—Although not a
major pest, the larva of this species when present in considerable
numbers may litter a yard in late summer with twigs from oaks,
elms, hickories, maples, and other trees. A clever animal, the
larva tunnels around a twig under the bark, cutting into the twig
to such an extent that it is easily broken off in the wind. Having
burrowed farther toward the tip of the twig, the pruner falls with
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 49
Fig. 35.—Periodical cicada: A, adults on trunk of tree; B, punctures
made in twig by adult female in laying eggs; C, eggs in tissue of twig. Dam-
age to oaks is very conspicuous following an outbreak of the cicada.
50 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
the twig to the ground, where transformation occurs. The adult
is a rather slender, brown beetle, about three-fourths inch long,
that emerges from the pupa. The female lays eggs in twigs in
early summer.
Control Measure 20 (end of circular).
Oak Kermes, Kermes pubescens Bogue, fig. 36.—Of most im-
portance on bur oak, but sometimes found on chinquapin, white
oaks, and red oaks, the oak kermes is closely related to the scale
Fig. 36.—Oak kermes: an infestation of this almost spherical scalelike
insect at the base of a new shoot.
insects. After wintering on the bark of twigs and branches, the
oak kermes migrates to a growing shoot. Where numerous indi-
viduals cluster around shoots and on the under sides of the leaves,
they distort and kill the new growth. The full-grown female
kermes is about one-eighth inch in diameter, almost spherical,
light brown in color, and covered with very fine fuzz. The male
produces a tiny white cocoon, in which it develops. In the spring,
each female lays several hundred light brown eggs under her
shell. In June, the reddish-brown crawlers that emerge from
the eggs leave the mother shell to find a suitable place for feed-
ing.
Control Measure 5 (end of circular), before the buds swell,
to kill the adults; or Control Measurve 3, about July 1, to kill the
crawlers.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 51
Leaf Miners, fig. 37.—Leaf miners, larvae of tiny moths,
fiies, sawflies, and small beetles, feed between the upper and
lower surfaces of the leaves of oaks and many other shade trees,
where they produce serpentine mines and blotches. Usually the
female places her eggs on leaf surfaces, and each young larva,
soon after it is hatched, bores into the leaf and proceeds to tunnel
in various directions. If a mined leaf is placed in front of a bright
light before the mine has been abandoned, the small larva that
did the damage can be seen between the two leaf surfaces.
Fig. 37.—Leaf miners: damage to oak leaves. Very small larvae of
several species of insects “mine” the leaves of oaks and other trees and de-
stroy the tissue between the upper and lower leaf surfaces.
52 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 38.—Oak galls of three types stimulated by small wasps belonging
to the family Cynipidae: A, gouty oak gall; B, wool sower gall; C, oak apple
rall. The abnormal growth of plant tissue is stimulated in some mysterious
fashion by these insects in the early part of the growing season. Each gall
houses a colony of the wasps until development is completed, when the gall
is abandoned.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 53
Control. In some species of leaf miners, the larvae drop to
the ground with the leaves in the fall; these larvae may be de-
stroyed if the leaves are burned. Until late years no insecticide
for the control of leaf miners has been available. Recent work
shows that Control Measure i4 or 15 (end of circular) is ef-
fective against some species.
Gall-Producing Insects, fig. 38.—Galls appear on oak twigs
in a variety of sizes and shapes that include irregular, bumpy,
warty growths and smooth, attractive, spherical formations.
These galls are not manifestations of a systemic disease and are
no cause for alarm. One of the unattractive kinds, the gouty oak
gall, fig. 38A, most often found on red oak, is produced by a small
wasp belonging to the family Cynipidae. Individual cells, each
inhabited by a larva of the wasp, make up the inside of the gall.
A woolly ball an inch or more in diameter, at first white but
brown when older, is known as the wool sower gall, fig. 38B.
Also produced by Cynipidae, this gall is not numerous enough to
cause severe damage. The oak apple, fig. 38C, is another spheri-
cal gall, green or brown in color, an inch or more in diameter,
which sometimes occurs in clusters. The spongy mass inside
each gall has a cell for the cynipid larva in the center.
Control. Damage to oaks by galls is rarely serious enough
to justify spraying. Since galls provide protection for the insects
inside, sprays applied after the galls develop are ineffective.
PINE
Sawflies, Neodiprion spp., fig. 39—The larvae of sawflies
are often seen as colonies of caterpillars feeding on pine needles.
They are especially injurious to young pines, which may be killed
by one defoliation. Each larva, about an inch long when grown,
has a red, brown, or black head, and many larvae have rows of
spots running lengthwise of their bodies. The insect overwinters
in a brown pupal case in the debris under a tree. Each less than
half an inch long, the seldom-seen, beelike adults emerge in the
spring. The female deposits eggs in slits she makes in pine nee-
dles. Although hard to see when first hatched, because of their
small size, the sawfly larvae soon attract attention by the disap-
pearance of needles required to meet their appetites. Sawrflies
may produce two generations a year.
Control Measure 2 (end of circular).
54 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 39.—Red-headed pine sawfly: four larvae and a pupal case (arrow)
on pine. Rows of black dots are conspicuous on the pale yellow larvae, which
consume the needles of young pines and may cause serious damage to the
trees. (Photograph from Pennsylvania State University.)
White-Pine Weevil, Pissodes strobi (Peck).—This pest pre-
fers white pine, but it feeds upon Scotch and jack pines, also.
Damage by the weevil is readily recognized by dead and dying
terminal leaders of infested trees. The overwintering adults,
each only about one-fourth inch long, feed on terminal twigs in
the spring. At this time of year, the female deposits eggs on the
terminal twigs. The larvae feed under the bark in the same gen-
eral region, causing enough damage to kill the twigs.
Control Measure 2 (end of circular) about April 15.
Pine Needle Scale, Phenacaspis pinifoliae (Fitch), fig. 40.—
Seales of this species appear as white specks along the needles of
its favorite hosts, Austrian and Mugho pines, as well as other
kinds of pines and some spruces. The purple insect under each
shell sucks out sap and chlorophyll, reduces the vitality of the
needles, and causes shedding of needles. Reddish eggs, which
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 55
Fig. 40.—Pine needle scale: infestation on pine. Scales appear as white
specks along the needles. (Photograph from Connecticut Agricultural Ex-
periment Station.)
56 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
overwinter under the shell of the female, hatch in the early sum-
mer. Each nymph or crawler moves to a new place, settles after
a few days, and inserts its beak into the leaf tissue to feed. It
soon begins to make a shell. This species of scale produces two
broods of crawlers during the summer.
Fig. 41.—Pine bark aphid: infestation on white pine. The aphids them-
selves are inconspicuous, but an infestation is easily recognized by the
splotches of cottony substance they produce.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES =f
Control Measure 12 (end of circular) in winter or Control
Measure 3 in June after eggs have hatched.
Pine Bark Aphid, Pineus strobi (Htg.), fig. 41.—White
patches of cottony substance on the trunks and limbs of pines
make an infestation of this pest easy to recognize. The insect
prefers white pine but sometimes feeds on Scotch and Austrian
pines. Its feeding does little damage to large, thrifty trees but
may weaken young trees.
The immature aphid, which overwinters under the “cotton,”
matures in the early spring and lays yellowish eggs, which also
are covered with “‘cotton.”” These eggs hatch in June, producing
both winged and wingless forms. The winged form apparently
migrates to other pines. The wingless form remains where it was
hatched and lays eggs which produce the overwintering nymphs.
Control Measure 3 or 8 (end of circular) applied forcefully
in June.
European Pine Shoot Moth, Rhyacionia buoliana (Schiff.).—
The black-headed, brown larvae of this species may cause serious
damage to Mugho, red, and Scotch pines by boring into the shoots,
causing them to turn brown and die. The partly grown, over-
wintering larvae become active in the spring and bore into unin-
fested shoots; pitch forms at the entrance holes they make. Pu-
pation occurs in early summer, and the female moth, soon after
emerging from her pupa, deposits eggs near the tips of twigs.
Each young larva bores into the bases of needles to feed; feeding
by the larva causes the needles to turn yellow. Later the larva
bores into a shoot for the winter.
Control Measure 2 (end of circular). Spray applications
must be timed to poison young larvae when they are active in
mid-April and late June or early July. Removal and destruction
of infested shoots in winter may help control this pest.
Nantucket Pine Moth, Rhyacionia frustrana (Comst.), fig.
42.—The smail, yellowish larva of this insect is only about one-
half inch long. It may kill many tips of red, jack, and other
pines. The adults, reddish-brown moths, emerge in the spring
from overwintering pupae. The female deposits flat, yellowish
eggs on the needles and terminal leaf buds of pines. The larvae
mine the needles at first but later bore down the centers of twigs.
They construct delicate webs that enclose the affected needles
and twigs. Larvae of the first two generations per year pupate
in buds.
58 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 42.
Nantucket pine moth: damage to pine shoots by the small,
yellowish larvae of this moth. Red pines and jack pines are favored by this
pest.
Control Measure 2 (end of circular). Spray should be ap-
plied in mid-April and late June. Infested shoots should be re-
moved and destroyed.
Zimmerman Pine Moth, Dioryctria zimmermani (Grote) .—
The light gray, reddish-yellow, or greenish larva of this species
tunnels under the bark around limbs and branches of pine, espe-
cially at the whorls, where it does serious damage. Presence of
larvae usually can be recognized by the great quantity of pitch
over the tunnels. Scotch and Austrian pines are particularly
susceptible to this insect.
The maximum flight of the adults, which are nocturnal,
dark gray moths, occurs about the middle of August, when the
female deposits eggs on the bark of pine. The larvae usually
work where bark is thin. Pupation occurs in the larval tunnels.
Control Measure 13 (end of circular) applied in early August.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 59
POPLAR
The fast-growing poplars, Lombardy, Carolina, aspen, and
cottonwood, are almost certain to be short-lived because of the
ravages of borers. Some of these borers are discussed briefly be-
low.
Poplar Borer, Saperda calcarata Say.—The white, cylindrical
larva, which does the boring, and the adults, bluish-gray beetles,
are each more than an inch long. Eggs deposited in slits in bark
in the summer produce the borers that work under the bark and
sapwood and into the heartwood of an infested tree. Frass or
sawdust at the base of a tree indicates the presence of borers.
Three years are required for the life cycle of this insect.
Control Measure 4 (end of circular). Heavily infested trees
should be cut down and burned in the early spring.
Cottonwood Borer, Plectrodera scalator (F.).—The adult
form of this insect is a large beetle with long, black antennae.
The female lays eggs in cavities dug in the bark. The eggs pro-
duce white, deeply constricted grubs that when grown are up to
2 inches in length. These grubs, the tunnels of which are plugged
with wood fibers, work near the bases of trees or even below
ground. Badly infested trees may be easily blown over. Two
years are required for the life cycle of this insect.
Control Measure 4 (end of circular) ; or wire screen may be
placed around the bases of trees to prevent egg laying.
Poplar and Willow Borer, Sternochetus lapathi (l.).—The
larva of this insect is a legless grub or borer, about one-half inch
long, that bores into poplars and willows. The adults are black
snout beetles or weevils. The borer feeds in the limbs and
branches, as well as in the trunk, of the tree it infests. It prefers
wood 2 or more years old.
Control Measure 4 (end of circular). Infested branches and
limbs should be removed and burned before July.
Carpenterworm, Prionoxystus robiniae (Peck).—The larva
of this insect is a pinkish, slightly flattened caterpillar, up to
214 inches long, that develops from an egg deposited in a bark
crevice by a large, gray moth. The carpenterworm requires 3
years to complete development, during which time the larva
mines and loosens the bark and drills large holes into the trunk
of the infested tree. It may deform trees and branches.
Control Measure 4 (end of circular).
60 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Cottonwood Leaf Beetle, Chrysomela scripta F.—The foliage
of cottonwood and willow is often skeletonized by the dirty yellow
larvae of this species. The overwintering form, a beetle about
one-fourth inch long, has a black head and thorax and yellowish
wing covers. In spring, it emerges from the debris about a tree.
The female deposits masses of yellow eggs on the under sides of
leaves. The larva eats the tissue of leaves, all but the veins, com-
pletes development in 2 weeks or so, and, attached to a leaf, pu-
pates with its head hanging downward. This insect probably
has two broods a year.
Control Measure 1 or 2 (end of circular).
Poplar Tent Maker, /chthyura ‘nclusa Hbn. —Silken tents
enclosing a branch or twig of a poplar are signs of colonies of the
black-mottled caterpillars that are the larvae of this insect. As
the caterpillars grow, they take more and more leaves into the
tent. The insect overwinters in the pupal stage. The female moth
that emerges from an overwintering pupa deposits masses of
eggs on leaves to produce caterpillars that feed in June. A second
brood of caterpillars occurs in August.
Control Measure 1 or 2 (end of circular) applied when cater-
pillars are small. Infested branches should be cut out and burned.
Oystershell Scale, fig. 5.—This is a common and destructive
pest of cottonwood. See under Ash. Control Measure 5 (end of
circular) in late winter or Control Measure 3 about the first of
June, after eggs hatch. Thorough spray coverage is essential.
PRIVET
Privet Thrips, Dendrothrips ornatus (Jablon.).—This thrips
in both adult and nymphal forms is a small, flat, elongate insect
that feeds in great numbers on privet foliage, withdrawing the
juices and chlorophyll. The adult thrips, dark brown and yellow,
have wings. The nymph, almost colorless at first, becomes lemon
yellow as it increases in size. Privet leaves affected by this insect
become dotted and dirty with excrement and they fall prema-
turely. Because this insect feeds at first on the under sides of
leaves, it often goes unnoticed until the leaves have been severely
damaged.
Control Measure 3 or 8 (end of circular) applied in June, or
when the thrips infestation occurs. DDT should not be used on
privet, as it may cause serious leaf drop.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES
Fig. 43.—Two-spotted spider mite: mites and eggs. The mites, which
vary in size with their stages of development, are even in the most advanced
stage barely visible to the naked eye. Most of the mites are found on the
under sides of infested leaves.
62 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
REDBUD
Oystershell Scale, fig. 5—See under Ash. Control Measure
5 (end of circular) in late winter or Contro! Measure 3 about the
first of June, after eggs hatch. Thorough spraying is essential.
Two-Spotted Spider Mite, Tetranychus telarius (L.), fig. 438.
—The foliage of redbud is sometimes infested with great num-
bers of green or yellowish mites of this species. The mites remove
so much chlorophyll and juice from the foliage that the leaves be-
come dry and drop prematurely. The overwintering female mites
move to the leaves in early summer to feed and deposit trans-
lucent, spherical eggs. Six-legged larvae hatch from the eggs in
a few days. After the first molt, the mites have eight legs. Follow-
ing two more feeding periods and molts, the mites become adult.
The mites of various stages differ in size but are similar in ap-
pearance. Males are slightly smaller than females, and their ab-
domens are more pointed than those of females. There may be a
number of generations of this mite during the summer.
Control Measure 9 (end of circular).
SPIREA
Spirea Aphid, Aphis spiraecola Patch, fig. 44.—This green
plant louse occurs nearly every spring in great numbers on the
tender shoots of spirea. Eggs deposited on spirea in the fall give
rise to mother aphids that produce living young in the spring.
Wingless and winged forms may be present; the latter migrate
to other host plants as the plant growth hardens. Quantities of
sticky honeydew are produced by an infestation of this aphid.
Control Measure 3 (end of circular).
SPRUCE
Spruce Spider Mite, Oligonychus ununguis (Jac.).—The
spruce spider mite is small, but its dense populations can do a
great deal of damage. It is one of the most troublesome pests of
arborvitae, spruce, and juniper. It lives on the juices of these
plants. When the sharp green color of the foliage begins to give
way to gray, and later brown, it is too late to prevent some de-
gree of damage, but prompt action may prevent serious damage
or death of the plants.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 63
Overwintering eggs at the bases of the needles of infested
plants produce tiny, light green mites in early spring. Through
a series of molts the mites mature into larger, darker green, or
almost black individuals, with spinelike hairs that curve back-
Fig. 44.—Spirea aphid: infestation of this green plant louse on a spirea
shoot. After sucking sap from the shoots of spirea for a short time in
spring, this aphid develops a winged form that migrates to other host
plants.
ward over their robust bodies. The mites can be seen as moving
specks on a white piece of paper or dish that has been held under
infested branches struck sharply with the hand. This species
has a number of generations in a season.
Control Measure 9 (end of circular) as soon as mites are de-
tected, usually in April or May.
64 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Cooley Spruce Gall Aphid, Chermes cooleyi Gill.—Gall aphids
of this species produce thick, elongate galls at the tips of twigs
of Colorado blue spruce, Sitka spruce, and Engelmann spruce.
The galls are so heavy that usually they cause the twigs to bend.
In midsummer, the galls open and the aphids emerge. Some of
the gall aphids develop wings. Gall aphids of the winged form
migrate to Douglas fir, where the females lay eggs. The eggs
and young gall aphids are covered with patches of cottony wax.
No galls develop on Douglas fir.
Eastern Spruce Gall Aphid, Chermes abietis L.—Gall aphids
of this species produce somewhat pineapple-shaped galls near the
bases of spruce twigs. Sometimes these gall aphids cause severe
damage to Norway spruce.
Control Measure 8 (end of circular) in late September or
October or in early spring.
Spruce Bud Scale, Physokermes piceae (Schr.), fig. 45.—The
mahogany-brown, globular scales of this species cluster at the
Fig. 45.—Spruce bud scale: infestation on spruce. The globular, ma-
hogany-brown scales resemble spruce buds and are difficult to detect.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 65
buds and nodes of spruce. The overwintering female fills her
shell, about one-eighth inch in diameter, with purple eggs in
June. In central Illinois, the eggs hatch about the first of July.
The flat, purple crawlers move away from their mother to settle
in a new place.
Control Measure 3 (end of circular) July 10-15.
Spruce Budworm, Choristoneura fumiferana (Clem.).—A
destructive forest pest that sometimes attacks ornamental
spruces, the larva of this species is a dark reddish-brown cater-
pillar about 1 inch long when grown. It feeds on the opening
buds and needles, tying them together with silk.
The overwintering caterpillar becomes active in the spring
and completes development. The adults, dull gray moths, emerge
from the pupal case in midsummer, when the female deposits
masses of overlapping, greenish eggs on the needles.
Control Measure 2 (end of circular) when caterpillars are
actively feeding.
Pine Needle Scale, fig. 40.—See under Pine. Control Meas-
ure 12 in winter or Control Measure 3 in June (end of circular).
Fig. 46.—Sycamore lace bug: adults. The bugs, which are black and
have almost transparent wings, are shown congregated on the bark of a
tree. They have sucking mouthparts and feed on the under sides of leaves.
(Photograph from Connecticut Agricultural Experiment Station.)
66 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
SYCAMORE
Sycamore Lace Bug, Corythucha ciliata (Say), fig. 46.—This
insect is probably the most common pest of sycamore. Both
adults and nymphs feed on the under sides of the leaves in great
numbers, withdrawing so much plant juice and chlorophyll that
the foliage becomes pale and dry. The leaves become dirty with
excrement. Both male and female are pretty insects; each is
about one-eighth inch long and has a black body and almost
transparent, lacelike wings held flat when at rest. By contrast,
the black, spiny nymph is ugly.
The overwintering female becomes active in early spring
and deposits eggs on the under sides of new leaves. The eggs
hatch in a couple of weeks, and each nymph molts five times be-
fore becoming an adult, 30 to 40 days later.
Control Measure 3 (end of circular) when the nymphs ap-
pear, usually in late May.
Bagworn, fig. 2.—This, the most common leaf eater on syca-
more, is discussed under Arborvitae. Control Measure 1, 3, or
77 (end of circular) as soon as the eggs hatch. Sprays applied
in late summer after the larvae stop feeding, or during the win-
ter, are ineffective. The worm infestation can be reduced by
picking and burning the overwintering bags.
Borers.—Newly set sycamores, like most other newly set
trees, are subject to attack by borers, especially the flatheaded
apple tree borer, fig. 34. Control Measure 4 (end of circular).
TULIPTREE
Tuliptree Scale, Towmeyella liriodendri (Gmel.).—Oval,
brown females of this species may be seen plastered on the bark
of lower branches and twigs of the tuliptree in summer. Great
quantities of honeydew drip from the scales. Each scale is more
than one-fourth inch across. Inconspicuous overwintering
nymphs, also plastered on the bark, grow rapidly in the spring
and early summer. The female reaches maturity in August and
apparently gives birth to living young.
Control Measure 5 (end of circular) in late winter.
Tuliptree Aphid, Macrosiphum liriodendri (Monell).—This
small, greenish aphid occurs in great numbers on the under
sides of the leaves of the tuliptree. Honeydew, which is secreted
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 67
in large quantities by the aphids, makes the leaves sticky and
drips on objects under the tree. Sooty mold often grows in the
honeydew and causes the leaves and other objects it covers to
appear black.
Control Measure 3 (end of circular).
WALNUT
Walnut Caterpillar, Datana integerrima G. & R., fig. 47.—
The larva of this species, a large, black caterpillar with gray
Fig. 47.—Walnut caterpillar: a colony of larvae. Walnut caterpillars,
reddish when small, later have black bodies covered with white hair. They
may completely strip the foliage from the trees they infest.
68 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
hairs, is the main leaf eater of walnut trees and, for some un-
known reason, is attracted to isolated trees. It is very fond not
only of walnut but of butternut, hickory, oak, honey locust, and
willow; sometimes it feeds on apple and other fruit trees. Each
caterpillar develops through a series of molts from one of many
eggs laid in masses on leaves of the host tree. An egg mass pro-
duces a colony of caterpillars that may destroy the foliage on a
Bees
a Zs
we
SS a
Fig. 48.—Willow aphid: an infestation of the wingless form on a twig.
This dusky, relatively large aphid withdraws juices from leaves, causing
them to wilt and drop.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 69
whole limb before moving to fresh leaves. The colonies migrate
downward on a limb or tree trunk, molt, and leave a clump of
skins the size of a man’s fist. When grown and about 2 inches
long, the caterpillars leave the infested tree and dig into the soil.
There they pass the winter in the pupal stage. The adults,
brownish moths, emerge in early summer. The female flies into
one of the preferred kinds of trees, where she deposits eggs.
Control Measure 1 or 2 (end of circular) just as soon as
feeding can be detected. Bands of sticky material around tree
trunks are of no benefit.
Black Walnut Curculio, Conotrachelus retentus (Say).—This
reddish-brown weevil feeds on tender shoots and foliage of wal-
nut for a while in the spring. The adult female makes in the
young walnuts crescent-shaped cuts in which she deposits eggs.
Feeding of the larvae that hatch causes the nuts to drop when
only about half grown.
Control Measure 1 (end of circular) applied to new foliage.
Fortunately this walnut pest is attacked by several parasites,
which help keep it under control.
WILLOW
Willow Aphid, Clavigerus smithiae (Monell), fig. 48.—This
rather large, dusky aphid may infest twigs and leaves of willows
during the summer. Unlike many kinds of aphids, this one is
restless, easily disturbed, and rapid in its movements. Both
winged and wingless forms may be present on an infested tree.
By withdrawing juices from leaves, this aphid may cause the
leaves to wilt and drop.
Control Measure 3 (end of circular).
Bagworm, fig. 2—See under Arborvitae. Control Measure
1, 3, or 11 (end of circular).
Borers.—See under Poplar. Control Measure 4 (end of cir-
cular).
Oystershell Scale, fig. 5—See under Ash. Control Measure
3 or 5 (end of circular).
YEW (TAXUS)
Black Vine Weevil. Brachyrhinus sulcatus (F.), fig. 49.—
Rapid dying of yew—dying similar to that caused by transplant-
70 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
ing shock—may indicate that the roots have been eaten by the
white, legless, crescent-shaped grubs of the black vine weevil.
The grubs feed on plant roots from late summer until late spring.
Development and transformation of this insect take place in the
soil, and the adult weevils make their way to the surface about
the first of June. The adults are seldom observed, as they hide
during most of the daylight hours and feed sparingly, mainly at
night, on the foliage toward the center of the plant. The female
does not deposit her eggs on a plant, as many insects do, but
simply drops them on the ground. This insect has only one gen-
eration a year. A long preoviposition period makes it possible to
time a control spray to kill all adults after they have emerged
from the soil and before they have dropped eggs.
Fig. 49.—Black vine weevil: larvae and damage to small yews. The
adult, a black snout beetle, is seldom seen.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 71
Control Measure 16 (end of circular) after all adults have
emerged from the soil. From southern to northern Illinois, this
period may vary from June 15 to July 15. The spray should be
applied to plants to the point of drenching them.
Fletcher Scale, Lecanium fletcheri Ckll., fig. 50.—This is a
soft scale, usually occurring sparsely on yew but sometimes as
heavy infestations that cause serious damage. The overwinter-
Fig. 50.—Fletcher scale: infestation on yew. The overwintering females
are pale yellow to brown in color and globular in shape.
ing female, pale yellow to brown in color and globular in shape,
lays eggs in May. One scale shell may contain 800 or more eggs.
The flat, yellow crawlers that hatch from the eggs in June move
away from the mother shell to settle and feed on new growth.
This insect has only one generation a year.
Control Measure 3 (end of circular) after all eggs have
hatched, about June 21 in central Illinois.
Termites, Reticulitermes spp.—Termites may attack yew,
especially plants near an infested building. The white, antlike
insects build mud runways about the base of a plant or in the
crotches of the branches or along the larger branches. They eat
72 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 51—Taxus mealybug: infestation on yew. The sooty mold on in-
fested needles makes the white, wingless insects conspicuous.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 73
the bark and cambium and may girdle and kill a branch or an
entire plant.
Control Measure 17 (end of circular).
Taxus Mealybug, Dysmicoccus cuspidatae (Rau), fig. 51.—
The taxus mealybug is an occasional pest of yew. Its name is
descriptive of the white, waxy, slow-moving, sucking insect seen
feeding in small colonies on the twigs and branches.
Control Measure 3 (end of circular). The spray should be
applied with force and repeated in 2 weeks.
POTENTIAL INSECT ENEMIES
There are several important shade tree pests that have not
yet, but may, become destructive in Illinois. Everyone should be
on the alert for them. Anyone finding an insect fitting one of the
Fig. 52.—Japanese beetle: adults. Both male and female adults are
principally metallic green in color and about a half inch in length. Each has
white spots on the tip of the abdomen.
descriptions below should place the insect in alcohol and send it
to the Illinois Natural History Survey, Urbana. Early knowledge
of the presence of a new pest may result in holding down an in-
festation or in wiping it out completely.
Japanese Beetle, Popillia japonica Newm., fig. 52.—The
Japanese beetle feeds on the foliage of a wide variety of trees,
shrubs, vines, and other plants. It is a ravenous feeder that oc-
curs in great hordes.
A native of the Orient, this insect was first found in the
United States in 1916, and isolated infestations now occur in
Illinois. The adults, metallic green beetles about one-half inch
long, have white spots on the tips of their abdomens, just back
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Fig. 53.—Gypsy moth: A, adult females; B, adult males; C, larvae; D,
egg clusters and pupae on the under side of loose bark. The female is buff
in color, the male dusky; the larva is covered with brown hair and has blue
and red tubercles along the back. The egg clusters are covered with tan
hairs. (Photographs from Connecticut Agricultural Experiment Station.)
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 75
of the wing covers. They are strong fliers. They are very fond of
eating ripening apples, corn silk, grape foliage, and soybeans.
The female deposits eggs in the soil to produce grubs that feed
on the roots of grasses. The grubs spend the winter in the soil,
resume feeding in the spring, complete growth, and pupate. The
adults emerge from the pupae in late June or July and feed for
several months. This insect produces one generation each year.
Gypsy Moth, Porthetria dispar (L.), fig. 53.—Of all the leaf-
feeding pests that attack shade and woodland trees, the cater-
pillar of the gypsy moth is the most destructive. It feeds on
nearly all deciduous trees, and, except in the early stages of its
development, on many evergreens. Most of the area infested by
this insect lies east of the Hudson River. An infestation in Mich-
igan was discovered recently, but there is good prospect of eradi-
cating it.
The female moth deposits eggs in hair-coated clusters on
tree trunks, buildings, and other objects. The full-grown cater-
pillar, 2 to 214 inches long, is covered with tufts of long brown
hair and has five pairs of blue tubercles along the back followed
by six pairs of red tubercles.
The insect overwinters in the egg stage. The eggs hatch as
the leaves of trees unfold in spring. The caterpillars feed for
about 2 months, during which time they may strip trees of their
foliage. Pupation occurs in cocoons fastened to tree trunks. The
adults emerge in late July, and the female deposits the eggs that
carry the species through the winter. The female is buff in color,
the male brown.
Brown-Tail Moth, Nygmia phaeorrhoea (Donov.).—The cat-
erpillar of this species feeds on the foliage of a wide variety of
trees, including oak, elm, maple, willow, apple, pear, and plum.
Like the gypsy moth, the brown-tail moth is confined mainly to
the New England states.
The male as well as the female is white, except on the tip of
the abdomen, which is covered with brown hairs. The caterpillar
is reddish brown and has a broken yellow stripe along each side
of its body. The body is covered with stiff barbed hairs, which
may cause a very irritating rash on human beings.
The partly grown caterpillar, which overwinters in a nest of
webbed leaves, feeds for a while in the spring before pupating.
The adults emerge in July, and the female deposits masses of
brown eggs on the under sides of leaves.
76 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
ABOUT INSECTICIDES
Insect control sometimes is based on the division of insects
into two groups: those with chewing mouthparts and those with
sucking mouthparts. A stomach poison is usually prescribed for
those with chewing mouthparts, a contact poison for those with
sucking mouthparts.
Lead arsenate is an example of a stomach poison and nicotine
sulfate an example of a contact poison. DDT and malathion may
act as either or both types of poison. This statement does not
mean that all insects can be controlled with DDT or malathion.
For example, while DDT is effective against a wide variety of
caterpillars, it does a poor job on bagworms. Unfortunately,
DDT kills many beneficial insects—those that prey on pests—
and thereby sometimes contributes to unusually heavy mite,
aphid, and scale infestations.
Many insecticides are available to the person wishing to
control insect pests of trees and shrubs. The trend is toward a
specific insecticide for a specific pest. However, the number of
insecticides recommended in this circular has been kept as low as
possible, consistent with practical usage and effective results.
The formulations recommended on pages 90—92 are for types
of sprayers shown in figs. 55-58 and the frontispiece. Formu-
lations for the mist blower, fig. 59, may require special con- |
sideration. A general rule to follow in formulating for the mist
blower is to multiply by six the quantity of insecticide recom-
mended for the hydraulic sprayer. Insecticide solut.ons or emul-
sions are handled by mist blowers better than are wettable pow-
ders in suspension. However, wettable powders mixed with
water can be used in a mist blower with suitable nozzle adjust-
ment and adequate agitation in the tank.
All insecticides should be handled as poisons. Some are more
poisonous to human beings than are others, and some are so haz-
ardous that they should be handled only by persons familiar with
them. The first step in handling all insecticides safely is to read
the label on the package, and the second is to follow the instruc-
tions given thereon.
Although insecticide applications are depended upon for the
control of most insect pests of trees and shrubs, other measures
are sometimes used: syringing mite infestations on plants with
a strong stream of water; picking and burning the overwintering —
ee - ~
" —y — 0
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES wT
bags of bagworms to destroy the eggs; covering young trees with
cheesecloth to protect them from cicadas; wrapping the trunks
of young trees with paper to protect them from borers, fig. 54.
Fig. 54.—Newly set tree, A, wrapped with paper to prevent damage by
borers. The paper, about 4 inches wide and specially designed for wrap-
ping trees, is spiraled about the trunk of the tree and held in place with a
stout cord, as shown in B.
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
ABOUT SPRAY EQUIPMENT AND ITS USE
A 2- or 3-gallon knapsack sprayer, fig. 55, is the smallest
equipment suitable for spraying shrubbery and small trees. The
low pressure and low rate of discharge of such equipment demand
tls
PEs 8
» heater Te See re Ee
oie oe SE a sae
Fig. 55.—Compressed air sprayer, a convenient sprayer for small jobs.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 79
careful work for complete plant coverage. The trombone-type
sprayer, shown in the frontispiece, develops adequate pressure
and is convenient for spraying a few shrubs and small trees. The
bucket-pump sprayer, fig. 56, also develops adequate pressure for
<r
if
>
(ieee!
a
Fig. 56.—Bucket-pump sprayer, an inexpensive but suitable sprayer for
shrubs and small trees. The spray material is mixed with water in a bucket
and kept mixed by agitation with a wooden paddle.
80 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
small trees and is useful for treating a larger number of plants. A
hand-operated wheelbarrow-type sprayer or small power sprayer,
fig. 57, is reeommended for any job involving medium-sized plants
or a large number of small plants.
Adequate spraying of large trees requires power equipment.
A conventional hydraulic sprayer, fig. 58, that develops 500-600
Fig. 57.—Small power sprayer. This is a satisfactory sprayer for shrubs
and small trees.
pounds pressure and has a pump that delivers 30—40 gallons per
minute is suitable for spraying large trees. However, if all the
spraying is done from the ground, a great deal of spray will be
wasted in trying to reach the tops of tall trees. Waste can be
reduced if some of the spraying is done from a tower built on the
sprayer.
A mist blower, fig. 59, is more suitable than a hydraulic
sprayer for use with large trees. In the mist blower, a spray con-
centrate is discharged into a blast of air that travels through an
outlet at a velocity of 100-120 miles per hour. The outlet can be
manipulated to direct the spray concentrate to all parts of even
large trees.
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 81
Incomplete spray coverage of a tree may serve to check the
ravages of a leaf eater, such as the cankerworm, but control of
scale insects or control of the bark beetle that transmits Dutch
elm disease requires complete coverage. This is difficult to obtain
even with the best of equipment. The tree must be sprayed sys-
tematically from many angles and at a time when the wind ve-
locity is essentially zero. Careful inspection of a tree or shrub
after spraying shows whether proper coverage has been obtained.
Fig. 58.—Power sprayer in operation. This machine, known as a hy-
draulic sprayer, will do an excellent job of spraying trees of small and
medium sizes.
82
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
This machine
Fig. 59.—Mist blower or roto-mist sprayer in operation.
is particularly useful for spraying large trees.
IN
DEX
This index includes technical and common names of insects and com-
mon names of trees and shrubs. Page numbers of illustrations are indicated
by boldface type. A page number for a subject may indicate the beginning
of the section or subsection in which the subject is discussed.
Names are
listed in the singular regardless of whether they appear in the text as
singular or plural.
A
micema snetsingerty ... . . . 936
MIRUUSHOMLIUS sens + -. +e, 11
Ailanthus 5 oe eae
webworm . . pen dF sat
American elm (see ‘also
Hint mee en... sm. 2l, 20,05
Anisota rubicunda owes AG
Jvalntcl 2 3G Se erraenee O-” a |
boxelder 12
Cooley spruce gall. " 20, 21, e
Eastern spruce gall
elm
cockscomb gall Borer Ay)
leaf : 28, 29
Norway-maple ; sey
painted maple s ay
pine bark 56, 57
spirea . 62, 63
tuliptree > AS
willow 68, 69
woolly elm 29
woolly hawthorn 5 om ET NC
Apple: 3... HPS 7a, (ates, TB
oak (gall) _ : 52,53
tree borer, flatheaded 46, 46, 48
Aphis spiraecola : 62
Arborvitae Ds 39, ‘43, 62, 66, 69
leaiaminer . . is alt 7
ae thuiella 3
(3) ; 15 ae 40, 60, 62, 69
borer . : 7,8
borer, red- headed seg Ah en VT
mountain ene eee ato
“finba. 2) Seis)
Aspidiotus
ancylus 28
perniciosus ; 18
RRVCDUMUUUT CU. ew ee 8
Austrian pine 54, 57, 58
B
Bagworm . . 9,9, 09, 43, 66, 69
Banded elm lesthooper : . Be
Bark
aphid, pine 56, 57
beetle
hickory 36
juniper 38
native elm
smaller European elm
Beetle
elm leaf
cottonwood leaf
hickory bark
Japanese
juniper bark
Wee 2 5 &
native elm bark
Birch
borer, bronze
skeletonizer
white
Bittersweet
Black
cherry
locust
vine weevil _
walnut curculio
Bladder gall, maple
Bladder-gall mite, maple
Blue spruce, Colorado
Borer ;
ash .
bronze birch -
cottonwood
dogwood
elm .
flatheaded apple tr ee
locust .
lilae
oak
poplar . ;
poplar and willow 3
red-headed ash
Boxelder b
bug =
aphid
Boxwood
leaf miner ‘
Brachyrhinus sulcatus
Bronze birch borer
Brown-tail moth . .
Bucculatrix canadensisella
Bud scale, spruce .
Budworm, spruce
Bug
boxelder
June
83
smaller European elm bark 31, 32
ol
31, 32
dl
1:
11
1, 2,48, 5 59, 66, 69
7, 8
84 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Bug—continued
sycamore lace - 65,66
Burtoak. oo ace Sate tea aOU
Buthernut a ae eee ee ce eo OS
Cc
Cankerworm, spring
peel 22e 23
Carolina poplar PPO as Ge AOO
Carpenterworm 48, 59
Catalpa 14,15
sphinx 14,15
Caterpillar
eastern tent iA, 113
walnut ‘ 67, 67
yellow-necked 16, 17, 36
Ceratomia catalpae .... . 14
Chermes
QDiCliSn Spee bcs cd eee Oe
cooleyi peer ie, eae 20, 64
Gherry: black <.~... stay sites, he
Ghimese-elin> 2. wuss oss 2s eae Se
Ghingquapin | s-..8lee ae se et 0
Chionaspis
COVNISL wee ee eee
FUT TUTE, oe oo een @. FAO
Chokecherry .. . soe Peet abil
Choristoneura fumiferana Sale EOD
Chrysobothris femorata . . . 46
Chrysomela scripta . .. . . 60
Cicada, periodical 48, 49
Citheronia regalis ...... 381
Clavigerus smithiae .... . 69
Cockscomb gall
aphigicelnial. 3, Goon) ieee ee
elm . Bee Bs 30
Colopha ulmicola Sone dir. eae? BVA!)
Colorado blue spruce ... . 64
Comstock mealybug .... . 16
Conotrachelus retentus . . 69
Cooley spruce gall gone 20, 21, 64
Cornisilkia RA 1
Corythuca ciliata A Ke a eee ae OO
Cottonwood ae 59, 60
borer . ahd are ake BeOS
leaf beetle Se, Sy (ene eee AP AOU
Cottony maple scale 43, 44
Crab. Tl, ase
Curculio, black ‘walnut ee ee Oo
Ovnipidae . one ee, 2 cee
Gynthia mochie.s. .- x), 3002 Beate
D
Datana
INLEGENTUNGs G0 a Gates Fa fee OU
ministra . . tits, Meee pelsy,
Dendrothrips Tavis feet a abo
Devil, hickory horned . .. . 37
Diaspis carueli . . ee Ok
Dichomeris moramnella BD ae hie le
Dioryctria zimmermami. . . . 58
Dogwood! “:) .. 5: sree O
borer |. 6..0 « < « see
scale) <.. 42 2. Voile O
Douglas fir 4 20, 21, 64
Drepanaphis acerifoliae Na
Dutch elm disease Bileo2
Dysmicoccus cuspidatae . . . 73
Eastern
spruce gall/aphid) +) se sneeOs
tent caterpillar . PEG:
Elm TAR 2 2eoe 27, 28, 32, 48, 75
American . : PAB 3B:
yolk, woolhy 5 5 a - 29
bark beetle
smaller European . 31, 32
native. 5 20 2 eee
borer 2's 5 ae Ome
Chinese . . <p ee 2
cockscomb gall aS) ck a ON
aphid. . 34> 44 cee
disease, Dutch Silay
leaf
aphid 28, 29
beetle . . | Sab
leafhopper, banded :| $y Soe
scale, European OAD
SEMIN COMMON Be 5 5 o co 5 ALU
Engelmann spruce .... . 64
Ennomos subsignarius . . . . 40
Eotetranychus multidigituli . . 43
Evriosoma
americaniun) . = 2) eee
crataegt . >. é.4.4) ee
Euonymus re Goo. Se a!
scale 2s. «. «4 OL Oe
European
elm
bark beetle, smaller . S1oz
scale. Pe 74s) Ds,
pine shoot moth .»: 2 ooo
red mite . 2. o... .. ) =e
F
Fall webworm . . a Os 2!
Flatheaded appelce borer 46, 46, 48
Fletcher scale . . ere Hal. 7/1!
Fir, Douglas 20, 21. 64
G
Galerucella xanthomelaena . . 24
Gall. so eS eS
aphid
Cooley spruce 20, 21, 64
eastern ‘spruce: =.) eos
elm cockscomb: =... ae
ILLINOIS TREES: THEIR INSECT ENEMIES
ENGLISH:
elm cockscomb 30
gouty oak. . 52,53
maple bladder . 45
mite, maple bladder- 5 als
oak apple . . debe
phylloxera, hickory . . Fai
psyllid, hackberry nipple Te MSS
wool sower : ear ¢
Gall-producing
insect shy a8
mite . ; 3
Gouty oak gall Dopo
Gossyparia spuria = 26
Grape . . . ALD
Green- striped mapleworm -2 46
Gypsy moth 5 Cae 74, 75
H
Hackberry . 35, 35
nipple gall psyllid_ 35
witches’-broom 35
Hard maple 47
Hawthorn . : ‘17, 17, 19, 36
aphid, woolly Th, We
leaf miner . 19, 20
Hemerocampa leucostigma 23
Hickory : > 36, 48;,68
bark beetle POG
gall phylloxera 37
horned devil 37
Homadaula albizziae 5 ai
Honey locust ; ; 43, 68
Horned devil, hickory BY
Hylurgopinus rufipes 31
Hypermallus villosus 48
Hyphantria cunea 9
I
Ichneumonidae 47
Ichthyura inclusa 60
Insect enemies, potential 18
Insect
gall-pr poucine 35
seale 1B
J
Jack pine : 54, 57, 58
Japanese beetle es, Ve
June bug : . 48
Juniper . ; Bil. ats, BY
bark beetle : : ee ates
scale . (il. ate!
webworm 38, 39
K
Kermes, oak . : 50, 50
Kermes pubescens 50
85
Is
Lace bug, sycamore . 65, 66
Lady beetle ay: 2
Leaf
aphid, elm . 28, 29
beetle
COLLONIWOOd! =) ess) 6) 60
elm re DAZ
CAC Waisman ts ot te fal 3
UM CVO RS as a ae ee ee BHI
arborvitae atPes iis We pase es tl
DOXWOOUM fe wins fe x. sf edi
hawthorn : 19, 20
Onkgurn eeuere ch noes. her ee es
Leafhopper, banded elm .. . 33
Mecanvinifleccherten se. 422 2 al
Lepidosaphes ulmi .. 3. .. 8
Beptocoris travittatus =. 8s). 2 LL
Lilac 40, 41
borer eek ee 7,40, 41
indenwece se SR th a peel)
moth, snow -white ME ace ree 0
Locust Metis sc 40, 42
blackwater whiner cc t40
borer aa 40, 42
honey Picea tons
mite . So At s)he’
Lombardy poplar Pte asus DO
Mousen(lice)eaplante 2.4 oa. eee
M
Macrosiphum liriodendri . . . 66
Magicicada septendecim . . . 48
Malacosoma americanum . 12
Maple 6, 14, 43, 47, 48, 15)
aphid
INOEWaVem ees. dl ose cee CAL
Painted@ess ses so eA
Inlaclkekere eealll 5 5 5 » 5 6 5 oe
bladder aot mite . 45, 45
Indl 5 ¢ seer ever AT
INGPAVcVaeec eens. ake no ten Spel 47
scale, cottony te 43, 44
44 45s
Nia glen orn: green- ae 2° == 46
Mavyabectle:.. te A\h ee De eye eo LAS
Mealybug
COmstOCk= fa eee ee IG
taxus : ieuticy
Megacyllene Pabaniae Glee ae mee O
Metatetranychus ulmi . . . . 18
MimOSaseni Tice 5: Seer eee Ag
WeEDWOLIN tsar renee) e 3
Miner
ShioopAatie GENE 5 6 5 6 6 A 7
boxwooduleat sy Satie or 14
hawthorn leaf 19, 20
Oaksleaiiet.) 4) ey th Me GAD.
Mite 3, oo
86 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Mite—continued
European red 18
gall-producing 3
locust . 43
maple bladder -gall 56. als
spruce spider 1 39102
two-spotted spider . SoOlo2
Monarthropalpus buxi : 14
Moth
brown-tail 75
cynthia : : a Pea,
European pine shoot : ~My
gypsy .. ; 74, 15
Nantucket pine 57, 58
regal . fol
snow-w hite linden : . AO
white-marked tussock 23, 24
Zimmerman pine - 908
Mountain ash ma flees:
Mugho pine : ; 54, 57
Myzocallis ulmifolii 5 Ay)
N
Native elm bark beetle 5, all
Nantucket pine moth se Eee DNeDS
Needle scale, pine 5 Bhs}, (OE
Neoclytus acuminatus soe! ee
Neodiprion spp. . 53
Nipple gall psyllid, hackberry 35
Norway maple : 47
Norway-maple aphid 47
Norway spruce ; 64
Nygmia phaeorrhoea . 75
oO
Oak. 14, 48, 51, 53, 68, 75
apple gall . Re ch Ss OY
bur 50
gall
gouty 574. 58%
wool sower aps, 3}
kermes 50, 50
leaf miner 5 jy!
red . 50, 53
white : 50
Oligonychus ununguis ; 62
Oystershell scale 8,9, 40, 60, 62, 69
P
Pachypsylla_ celtidis-mamma 35
Pachysandra 33
Painted maple aphid | 47
Paleacrita vernata 21
Pear = tS
Periodical Cee 48, 49
Periphyllus
lyropictus 47
negundinis 12
Phenacaspis pinifoliae
Phloem necrosis ;
Phloeosinus dentatus .
Phyllophaga spp. .
Phylloxera caryaecaulis
Phylloxera, hickory gall
Physokermes piceae
Pigeon tremex
Pine F
Austrian .
bark aphid
jack .
moth
Nantucket
Zimmerman
Mugho ees
needle scale. .
red
sawfly, red- headed .
Scotch :
shoot moth, European
white Sk; Be
Pineus strobi .
Pissodes strobi
Plant louse (lice) .
Plectrodera scalator
Plum
Podosesia
syringae
fraxini
syringae
Popillia japonica
Poplar
and willow borer.
borer
Carolina .
Lombardy
tent maker. .
Porthetria dispar :
Potential insect enemies
Prionoxystus robiniae
Privet
thrips : :
Profenusa canadensis
Pruner, twig
Pseudococcus cometoee ;
58, 54, 55, 58
. 48, 59, 69
54, 57, 58
Psyllid, hackberry nipple all 35
Pulvinaria innumerabilis
Putnam scale
Redbud . .
Red-headed
ash borer .
pine sawfly .
Red
mite, European
oak
pine .
Regal meee
a HR a
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 87
meticulitermes spp. ... .. T1 Norway. sce ees - Ge
Rhyacionia SIG Oc) seas Ps. oP peo eee OA.
AT UNIDL Meee as, eS a BT Spldersmite. 2) tee ww T89e62
frustrana 57 Sternochetus lapathi. . . . . 59
SIVCAMOLCh a ak LO om et: 866
S PACE LDUS che tana. cs oe MOOS EG
PEIOMCHMERL eS OB iz
Banmeoseiscale.. . ... ... 18,18
Saperda aes tage diso- Yew) 5 =. = . 69
BHCOTUCOEES ee PEO 6 ee = | D9 mealybug 12, 13
Peiitook 5.2... 29 ‘Tent ..
Sawfly .. Mee Us ae DS caterpillar, eastern IPA 1183
red-headed pine Peete. 8 Sod. a nae, jee 5 45 5 5 5 « (AD)
Seale ermites 7. ol Sane cee a |
cottony maple 43,44 Tetranychus telarius y NaBu Ee
Boewoodls. . ... =. =. . 20 Lhamnosphecia scitula .;: . . 20
euonymus AW 33,34 Thrips, privet . . Pesan ee MO)
European elm : Be e26 Thyr idopterix ephemeraeformis 5
Fletcher ....... 71,71 £‘Youmyella liriodendri
MSCCHMEEE ke. Ss ys oe 1,2 ©6Tree
juniper . 7, 37, 38 borer flatheaded apple : ine 46, 48
oystershell 8, 9, 40, 60, 62, 69 Omnheavent ss: Bag 8G
pine needle . . . 54,55,65 Tremex columba Sane. Sheree ca MOC ff
Putnam 27, 20 ea DrCMexspISCONn sn ee a e ATT
San Jose. 18,18 popmote Pe eee me eh cc oP
scurfy 26, 27 ey ol aKol 5) aw Soe te eh eh Gon, Ge Pah 6
spruce bud vn 64, 64 scale . . 66
tuliptree .. ete. 66 usnock moth, white- marked 23, 24
Scaphoideus luteolus Tee eat OO wig pruner .. 48
Scolytus Two-spotted spider ‘mite , 33, 61, 62
WMMGISEMIULUS Is 6... ss 8 OL
WUGdrISpINOSUS . |. . . . « 9306 U
Seotch pine : 04, 57, 58
Seurfy seale . ee 3 tis 26, 27 r . . P
a Seteniye 5G Unaspis cuonymt << . . . =. « 33
Shoot moth, European p joe 5 5 Ll Vv
Sitka spruce .. : Aaa ie OO:
Skeletonizer, birch . . . . . 11 Waeee SSPE
Smaller European Vase es quadripedes. . . . 45
aeibaetien. 31, 32 ine weevil, black 69, 70
Snow-white linden moth . . . 40
Soft maple 42, 44, 45, 45 WwW
Meer ee we : é
Spanworm, elm . . .. 49 Walnut Pea eee caer 67
Sphaerotheca phytoptophila + Eneroo Bcd 75 a ey set
Sphinx, catalpa P 14,15 Weevil. Pag eee ee tee ERS Ere
ee ite 7 30. 62 black vine . ss 69, 70
1X hite-pi BS peer mey ahs Fae
two- spotted . 33, 61, 62 eta ae a
a ae ailanthus Ai a eK ee ee ed
. : , alee ee ee ee) 9110-94
Spring Eaakervorn 2, 22, 20 juniper . é 38, 39
Spruce 7, 62, 64 mimosa . 43
pee scale = 64, 64 vine marked tussock moth . 23, 24
udworm . me ee OD ite
Melorado blue... .. . 64 inches pe eae eet ee aL:
mocelmann . . . . . . . 64 Cakes ape weet ne 5 LD)
gall aphid pine : 54, 56, 57
Cooley > 20521764 weevil ; 54
eastern eee OA. Se Wallow, 60, 68, 69, m5
88
Willow—continued
aphid
borer, poplar and
Witches’-broom
Wool sower gall
W oolly
elm aphid . .
hawthorn aphid .
ILLINOIS NATURAL HISTORY SURVEY CIRCULAR
68, 69
5 oo Bh)
35, 36
52, 53
yy
Yellow-necked caterpillar 16,17,
Yew (taxus)
Z
Zimmerman pine moth
COON Ts
47
36
72
58 .
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES
SPRAY PREPARATION TABLES
89
Table 1.—Proportionate quantities of liquid insecticides required to make
various quantities of spray.
~ Gallons | ; Spa eee reir Wi:
of Spray Quantity of Liquid Insecticide
Desired ; ai
100 | 1 pint 1 quart 1 gallon
50 lg pint 1 pint 2 quarts
25 | 4 pint 14 pint 1 quart
5 2 tablespoons | 4 tablespoons 6 ounces
1 | 1 teaspoon 2 teaspoons 3 tablespoons
Table 2.—Proportionate quantities of powdered insecticides
various quantities of spray.
~ Gallons — A
of Spray | Quantity of Powdered Insecticide
Desired 2 =
100 1 pound 2 pounds 4 pounds
50 _ 14 pound 1 pound 2 pounds
25 | 14 pound 14 pound 1 pound
5 1 tablespoon* 2 tablespoons* 4 tablespoons*
1 1 teaspoont 4 teaspoonst 1 tablespoon*
*Heaping +Level
2 gallons
1 gallon
2 quarts
12 ounces
5 tablespoons
required to make
8 pounds
4 pounds
2 pounds
8 tablespoons*
2 tablespoons*
90 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
CONTROL MEASURES
Following are the control measures mentioned on previous
pages of this circular. In most instances, formulas given are for
100 gallons of spray. The amounts of insecticides to be used for
small quantities of spray can be calculated from information
given in tables 1 and 2, page 89.
Control Measure 1.—Apply a lead arsenate spray: 4 pounds
of lead arsenate to 100 gallons of water.
Control Measure 2.—Apply a DDT spray: 2 pounds of 50 per
cent DDT wettable powder or 2 quarts of 25 per cent DDT emul-
sifiable concentrate to 100 gallons of water. Both lead arsenate
and DDT are effective against most leaf-eating insects. Where
either insecticide will do the job, lead arsenate should be used,
because of the aphid and mite infestations likely to follow re-
peated use of DDT.
Control Measure 3.—Apply a malathion spray: 1 quart of 50
per cent malathion emulsifiable concentrate or 4 pounds of 25
per cent malathion wettable powder to 100 gallons of water.
CAUTION: Malathion may injure Cannart red cedar, Juniperus
virginiana cannarti.
Control Measure 4.—Prevention of borer attack is more suc-
cessful than attempts at a cure. To discourage borer attack, keep
the trunks of newly set trees wrapped with heavy paper for the
first 2 years, or until the trees are established and growing vig-
orously. Special paper, 3 to 4 inches wide, in rolls suitable for
spiral wraps can be purchased. Start the wrap just below the
lowest branch and spiral it downward to the ground. Heap soil
around the base of the tree to close the space between the wrap
and the ground. Secure the wrapping in place with stout twine,
fig. 54. Keep the soil well watered, as drought-weakened trees
are attractive to borers.
Borer attack can be prevented, for the most part, by a DDT
spray applied to tree trunks: 4 pounds of 50 per cent DDT wet-
table powder or 1 gallon of 25 per cent DDT emulsifiable concen-
trate to 100 gallons of water. Designed to kill young borers as
they hatch from eggs on the bark, the spray should be applied
at monthly intervals throughout the summer, beginning about
May 1. Application of DDT to the entire tree is not recommended
unless necessary, as such application may result in serious infes-
tations of mites and aphids. A durable insecticide deposit can be
ENGLISH: ILLINOIS TREES: THEIR INSECT ENEMIES 91
made from DDT, powdered skim milk, and water. To a mixture
of 4 parts of 50 percent DDT wettable powder and 1 part of pow-
dered skim milk, enough water is added to make a smooth slurry
that can be applied to the trunks of trees with a paint brush.
Dead and dying branches should be pruned from infested trees
and burned. Borers in the wood can be killed if the tunnels are
cleaned out with a piece of wire and carbon disulfide or nicotine
sulfate is injected into the holes with an oil can. The holes
should be plugged with putty after treatment. Carbon disulfide is
highly inflammable and can be ignited by a spark or cigarette.
Control Measure 5.—Apply an oil spray while the plants are
dormant: use an emulsifiable dormant oil diluted with water ac-
cording to directions of the manufacturer.
Control Measure 6.—Clip off and destroy infested branches
or burn out the webs with a torch.
Control Measure 7.—Eliminate local infestations by spray-
ing the bugs on the trunks of trees and on the foundations of
buildings with a lindane or a dieldrin preparation: 1 pint of 20
per cent lindane emulsifiable concentrate to 5 gallons of water,
or 1 pint of 20 per cent dieldrin emulsifiable concentrate to 10
gallons of water. Repeat applications as needed.
Control Measure 8.—Apply a lindane spray: 1 pint of 20 per
cent lindane emulsifiable concentrate or 1 pound of 25 per cent
lindane wettable powder to 100 gallons of water.
Control Measure 9.—Spray with one of the following mate-
rials: 114 to 2 pounds of 15 per cent Aramite wettable powder or
25 per cent chlorobenzilate wettable powder to 100 gallons of
water. Or use Control Measure 3 at 2-week intervals until the
infestation is eliminated.
Control Measure 10.—Spray with one of the following mate-
rials: 1 quart of 20 per cent lindane emulsifiable concentrate or
1 quart of 15 per cent dieldrin emulsifiable concentrate to 100
gallons of water.
Control Measure 11.—Spray with toxaphene: 3 quarts of 60
per cent toxaphene emulsifiable concentrate to 100 gallons of
water.
Control Measure 12.—In late winter, apply a lime sulfur
spray: 1 gallon of liquid lime sulfur to 10 gallons of water. CAU-
TION: Lime sulfur will blacken house paint.
Control Measure 13.—Apply a DDT spray: 2 gallons of 25
per cent DDT emulsifiable concentrate to 100 gallons of water.
92 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47
Control Measure 14.—Apply a lindane spray: 2 quarts of 20
per cent lindane emulsifiable concentrate to 100 gallons of water.
Control Measure 15.—Apply an aldrin spray: 2 quarts of 25
per cent aldrin emulsifiable concentrate to 100 gallons of water.
Control Measure 16.—Spray with aldrin, dieldrin, or hep-
tachlor: 1 pound of actual toxicant per 100 gallons of water. This
rate means 2 pounds of 50 per cent or 4 pounds of 25 per cent wet-
table powder per 100 gallons of water.
Control Measure 17.—Inject diluted chlordane under and
around the root mass. For medium-sized plants, use about 1 gal-
lon of a mixture containing 1 gallon of 45 per cent chlordane
emulsifiable concentrate to 100 gallons of water.
Control Measure 18.—Remove and burn all dead and dying
elm trees, limbs, and branches before European elm bark beetles
emerge in the spring. Also promptly remove and burn trees in-
fected with Dutch elm disease. Bark beetle feeding and the
spread of Dutch elm disease can be reduced by spray applications
of special DDT formulations, but the practical aspects and lim-
itations of such a spray program should be well understood be-
fore it is undertaken. Special information on Dutch elm dis-
ease and phloem necrosis is available from the Illinois Natural
History Survey, Natural Resources Building, Urbana, Illinois.
Control Measure 19.—Promising results in control of the |
periodical cicada have recently been obtained with a spray con- —
taining 1 pound of 50 percent Sevin per 100 gallons of water. —
Small trees can be protected by a covering of cheesecloth over
each tree.
Control Measure 20.—Gather up and burn infested twigs.
Some Recent Publications of the
It“inois NaruraL History SURVEY
BULLETIN
Volume 26, Article 1.—The Mayflies, or Ephem-
eroptera, of Illinois. By B. D. Burks. May,
1953. 216 pp., frontis., 395 figs., bibliog. $1.25.
Article 2.—Largemouth Bass in
Coles County, Illinois. By
Volume 26,
Ridge Lake,
George W. Bennett. November, 1954. 60
pp., frontis., 15 figs., bibliog.
Volume 26, Article 3.—Natural Availability
of Oak Wilt Inocula. By E. A. Curl. June,
1955. 48 pp., frontis., 22 figs., bibliog.
Volume 26, Article 4.—Efficiency and Selec-
tivity of Commercial Fishing Devices Used
on the Mississippi River. By William C.
Starrett and Paul G. Barnickol. July,
1953. 42 pp., frontis., 17 figs., bibliog.
Volume 26, Article 5.—Hill Prairies of Illi-
nois. By Robert A. Evers. August, 1955.
80 pp., frontis., 28 figs., bibliog.
Volume 26, Article 6.—Fusarium Disease of
Gladiolus: Its Causal Agent. By Junius L.
Forsberg. September, 1955. 57 pp., frontis.,
22 figs., bibliog.
Volume 27, Article 1—Ecological Life History
of the Warmouth. By R. Weldon Larimore.
August, 1957. 84 pp., color frontis., 27 figs.,
bibliog.
CIRCULAR
39.—How to Collect and Preserve Insects.
By H. H. Ross. June, 1953. (Fourth print-
ing, with alterations.) 59 pp., frontis., 65
figs.
42—Bird Dogs in Sport
By Ralph E. Yeatter.
pp., frontis., 40 figs.
43.—Peach Insects of Illinois and Their Con-
trol. By Stewart C. Chandler. December,
1950. 63 pp., frontis., 39 figs.
45.—Housing for Wood Ducks. By Frank C.
Bellrose. February, 1955. (Second print-
ing, with revisions.) 47 pp., illus., bibliog.
46.—Illinois Trees: Their Diseases. By J.
Cedric Carter. August, 1955. 99 pp.,
frontis., 93 figs. Single copies free to Illi-
nois residents; 25 cents to others.
and Conservation.
December, 1948. 64
BIOLOGICAL NOTES
28.—Home Pools and Homing Behavior o
Smallmouth Black Bass in Jordan Creek
By R. Weldon Larimore. June, 1952. 1
pp., 5 figs., bibliog.
29.—An Inventory of the Fishes of Jorda
Creek, Vermilion County, Illinois. By k
Weldon Larimore, Quentin H. Pickering
and Leonard Durham. August, 1952. 2
pp., 25 figs., bibliog.
30.—Sport Fishing at Lake Chautauqua, nea
Havana, Illinois, in 1950 and 1951. B
William C. Starrett and Perl L. McNei
Jr. August, 1952. 31 pp., 22 figs., bibliog.
31.—Some Conservation Problems of th
Great Lakes. By Harlow B. Mills. Octe
ber, 1953. (Second printing.) 14 pp., illus
bibliog.
32.—Some Facts About Illinois Snakes an
Their Control. By Philip W. Smith. N«¢
vember, 1953. 8 pp., 11 figs. 10 cents.
33—A New ‘Technique in Control of th
House Fly. By Willis N. Bruce. Decen
ber, 1953. 8 pp., 5 figs.
34.—White-Tailed Deer Populations in Ilk
nois. By Lysle R. Pietsch. Jume, 1954. 2
pp., 17 figs., bibliog.
35—An Evaluation of the Red Fox. BE
Thomas G. Scott. July, -1955. (Secon
printing.) 16 pp., illus., bibliog.
36.—A Spectacular Waterfowl Migratic¢
Through Central North America. By Frar
C. Bellrose. April, 1957. 24 pp. 9 figi
bibliog.
37.—Continuous Mass Rearing of the Eur
pean Corn Borer in the Laboratory. Ff
Paul Surany. May, 1957. 12 pp., 7 figs.
MANUAL
3.—Fieldbook of Native Illinois Shrubs. }
Leo R. Tehon. December, 1942. 307 py
4 color pls., 72 figs., glossary, index. $1.7
4.—Fieldbook of Illinois Mammals. By Dona_
F. Hoffmeister and Carl O. Mohr. Jun
1957. 233 pp., color frontis., 119 figs., glo
sary, bibliog., index. $1.75.
List of available publications mailed on request.
Single copies of ILL1nois NATURAL History SuRveEY publications for which no price is liste
will be furnished free of charge to individuals until the supply becomes low, after which
nominal charge may be made. More than one copy of any free publication may be obtain¢
without cost by educational institutions and official organizations within the State of Illinoi
prices to others on quantity orders of these publications will be quoted upon request.
Address orders and correspondence to the Chief
ILLINoIs NATURAL History SURVEY
Natural Resources Building, Urbana, Illinois
Payment in the form of money order or check made out to State Treasurer of Illino
Springfield, Illinois, must accompany requests for those publications on which a price is S!
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