:W.m^^"--j)

A Guide to

Insect Injury

of Conifers

in the

Lake States

U.S. Department of Agriculture

Forest Service

Agriculture Handbook No. 501
A GUIDE TO INSECT INJURY

OF CONIFERS

IN THE LAKE STATES

by

Louis F. Wilson, Principal Insect Ecologist

North Central Forest Experiment Station

Agriculture Handbook No. 501

Forest Service

United States Department of Agriculture

Washington, D.C. May 1977
FOREWORD

This booklet updates and replaces the popular 1962 bulletin

"Identification of Conifer Insects by Type of Tree Injury, Lake

States'' by H. J. MacAloney and D. C. Schmiege, published as Station Paper 100 of the Lake States Forest Experiment Station. The

original publication included about 60 major insect pests important

primarily to several forest conifers in the Lake States. This fully

revised and expanded version includes descriptions of more than

165 insect pests and several important diseases (that could be

easily confused v^ith insect damage) found on 19 conifers in the

Lake States. It is basically a pictorial key of conifer injury to assist

Extension entomologists, forest managers, and plant inspectors in

identifying insect and disease problems.

Cover: Red pine with severe post-horn injury from European pine shoot moth.

For sale by the Superintendent of Documents, U.S. Government Printing OfRce

Washington, D.C. 20402 - Price $3.15 (paper cover)

stock Number 001-000-03611-4

Class A 1.76:501

11
CONTENTS

Page

INTRODUCTION 1

Tree Damage 1

How To Use This Manual 1

INJURY DIAGNOSIS 2

Symptoms and Signs 2

Types of Injury 2

IDENTIFICATION KEY TO CONIFEROUS TREES

OF THE LAKE STATES 4

DEFOLIATING INSECTS 9

Sawflies 9

Leaf Beetles 24

Grasshoppers and Walkingsticks 25

Webless Moths 26

Budworms, Tubeworms, and Webworms 28

Budworm Moths 30

Needle Miners 33

SAPSUCKING INSECTS, MIDGES, AND MITES 36

Spittlebugs 37

Scales 41

Plant Lice 44

Gall Aphids 46

Thrips 49

Midges 49

Mites 51

SHOOT, STEM, AND ROOT INSECTS 53

Shoot and Bud Moths 53

Pitch-Mass and Blister Makers 56

Weevils 58

Bark and Ambrosia Beetles 67

Wood Borers 73

Ants and Termites 77

White Grubs -_ 78

CONE INSECTS 80

Cone Beetles 81

Cone Moths 82

Coneflies 84

111
Page

NONINSECT MALADIES EASILY CONFUSED

WITH INSECT DAMAGE 84

Diseases 85

Animals 89

Other Agents - 91

PLATES 95

PLATE PHOTO CREDITS 204

INDEX TO INSECTS, BY HOST PLANTS 207

GLOSSARY 214

GENERAL INDEX 215

IV
PLATES

Page

Plate 1.—Conifers 96

Plate 2.—Conifers 98

Plate 3.—Conifers 100

Plate 4.—Foliage injury without webbing 102

Plate 5.—Foliage injury without webbing 104

Plate 6.—Foliage injury without webbing 106

Plate 7.—Foliage injury without webbing 108

Plate 8.—Foliage injury with webbing 110

Plate 9.—Foliage injury with webbing 112

Plate 10.—Foliage injury and webbed concealments 114

Plate 11.—Foliage injury and webbed concealments 116

Plate 12.—Foliage discolored 118

Plate 13.—Foliage discolored 120

Plate 14.—Foliage malformed 122

Plate 15.—Foliage spotted or discolored 124

Plate 16.—Foliage spotted 126

Plate 17.—Scales and aphids 128

Plate 18.—Scales and aphids 130

Plate 19.—Scales and scalelike fruit 132

Plate 20.—Woolly aphids and scales - 134

Plate 21.—Aphids 136

Plate 22.—Frothy concealments 138

Plate 23.—Galls 140

Plate 24.—Galls 142

Plate 25.—Galls 144

Plate 26.—Galls 146

Plate 27.—Galls 148

Plate 28.—Galls 150

Plate 29.—Bud injury 152

Plate 30.—Shoot injury 154

Plate 31.—Shoot injury 156

Plate 32.—Shoot injury 158

Plate 33.—Shoot injury 160

Plate 34.—Shoot injury 162

Plate 35.—Branch injury 164

Plate 36.—Branch injury 166

Plate 37.—Pitch exudates (tubes) 168

Plate 38.—Pitch exudates (blisters) 170

Plate 39.—Pitch exudates 172

Plate 40.—Pitch exudates 174

Plate 41.—Pitch exudates 176
Page

Plate 42.—Stem injury 178

Plate 43.—Stem injury 180

Plate 44.—Stem injury 182

Plate 45.—Stem injury 184

Plate 46.—Stem injury 186

Plate 47.—Root and bark injury 188

Plate 48.—Root collar injury 190

Plate 49.—^Wood injury 192

Plate 50.—Wood injury 194

Plate 51.—Wood injury 196

Plate 52.—Wood injury 198

Plate 53.—Cone injury 200

Plate 54.—Cone injury (red pine) 202

VI
INTRODUCTION

Tree Damage

Insects, abundant and important members of natural communities, often feed and live on trees, sometimes damaging them. Conifers have economic value for lumber, paper, and Christmas trees,

as well as aesthetic value around homes, along roadsides, and in

parks. Insects and disease can reduce the value of this resource.

The term damage often connotes an undesirable condition that

requires remedial action, but this is not alv^ays the case. Trees and

insects have evolved together through eons of time and are adapted

to one another. Trees can tolerate surprising amounts of insect

damage v^ith little or no effect on grov^th and survival. The damage

described in this guide does not always imply the need for insect

suppression or control, but insect damage does sometimes become

intolerable ; remedial action is then indeed required.

The insects and the host conifers treated in this publication are

confined principally to the three Lake States—Minnesota, Wisconsin, and Michigan. A few insects from bordering States and adjacent Canadian Provinces are included because they injure the same

conifers and are therefore potential Lake States pests.

Most insects that inhabit conifers can be identified easily by

entomologists, but because insects are elusive and secretive creatures, they are not always available for identification when the

injury is discovered. More often than not, the Extension entomologist, forest manager, or plant inspector is confronted with an

injured conifer but no visible insect; thus, a practical guide is

needed to help identify conifer insects by the damage they do. This

manual attempts to be that guide.

How to Use This Manual

Read the first part for background information about injury

diagnosis, then go to the next section on identifying the host tree,

if you do not know what species it is. After identification, either

turn to the section of the guide that is appropriate for the part of

the tree that is injured or examine the plates, generally arranged

by the part of the tree that is injured, until something appears

similar to the injury. Compare the symptoms and signs given in

the text or shown on the plate with those observed on the host to

determine if they match. If the injury appears serious, consult a

specialist to determine the course of action. Do not rely on this

guide alone where high values or costs are of concern, unless you

are experienced with the pests involved.
INJURY DIAGNOSIS

Symptoms and Signs

Accurate diagnosis of tree injury and identification of the cause

are based on skillful observation and interpretation of available

information. When the causal agent is not present or is difficult to

observe, the diagnostician must rely entirely on symptoms and

signs. Experience is the greatest asset in diagnosis.

The symptoms of an injury, such as unusual color, missing foliage, malformations, etc., are signals that something is v^rong v^ith

a tree. Symptoms are helpful in diagnosis and often give some clue

to the probable causes, but are seldom relied on entirely because

many insects, diseases, and other agents produce similar symptoms and one agent may produce several different symptoms.

Symptoms also change; yellov^ foliage may give v^ay to brown

foliage and then later to missing foliage if the tree or affected part

dies. Furthermore, two or more agents may injure the tree simultaneously, producing not only their usual symptoms but also new

ones from their interactions. Sometimes a primary agent that has

unrecognizable symptoms may weaken the host; then secondary

insects or diseases invade and destroy the host while showing only

their symptoms.

Signs of attack, on the other hand, are more useful for identification than symptoms and are often the only way to distinguish and

separate one type of agent from another. Signs include artifacts

(webs, cases, bags), debris (cast skins), excretions, pitch exudations, galleries, associated insects or fungi such as ants and sooty

mold, colored streaks, etc. Of course, if two insects have the same

symptoms and signs, the agents themselves must be identified.

The primary agent becomes more and more difficult to identify

as time elapses after injury because both symptoms and signs

change. If vigorous, a tree will attempt to heal itself and may mask

or outgrow the injury; if weak, it will suffer attack from other

insects and fungi. Signs such as webs, excrement, cast skins, etc.,

also deteriorate with time, but some may remain intact for a year

or more. The descriptions and illustrations presented here are

mostly for fresh symptoms and signs; whenever feasible, later

symptoms and signs are also given.

Types of Injury

Discolored foliage.—Discolored foliage is a symptom that can be

caused by injury anywhere in the tree—roots, trunk, branches, or

needles. Discolored single needles or small groups of needles

usually indicate that the injury is on the needle itself. When a
cluster of needles is discolored (flagging), the injury is likely to

be found within or at the base of the discolored section of the twig

or branch. Sometimes flagging is also caused by nutrient deficiencies or root injury from certain insects and diseases. Blackened

foliage and bark are indicative of soft scales, aphids, or spittlebugs,

and are caused by a sooty mold fungus that grows on the sugary

honeydew and spittle of these insects. Discoloration of needles or

shoots can also be due to the eggs or bodies of the insects themselves; that is, there may be yellow eggs or red-brown scale insects present. In these instances you can identify the pest directly.

Missing foliage.—Missing foliage results not only from insect

feeding but also from climatic, insect, or disease injury on other

parts of the tree. Notched, broken, or hollowed-out needles are

signs of direct feeding. A cluster of missing needles may indicate

a defoliator if the surrounding foliage or area beneath the injury

shows frass, webs, cocoons, or cast skins. The pattern of defoliation

is diagnostic for some defoliators, but they are sometimes difficult

to identify from signs alone.

Stunted and deformed tissues,—Galls, swellings, and fasciations are abnormal growths on needles, shoots, stems, roots, or

cones that result directly from recent injuries. Excessive branching, forking, and crooking are symptoms of past injury. Reduced

tree growth or stunting can result from injury anywhere in the

tree. Stunting may occur gradually or be delayed until a year after

the insect causing it has departed. Diagnosis is sometimes difficult.

Pitch exudations, artifacts, excretions,—Although not types of

injury per se, signs such as exudates, artifacts, and excretions are

useful in pinpointing the site of the injury and the insect pest, or

at least where it was. Insects feeding or tunneling in the shoots or

stems of living conifers often have a pitchy exúdate surrounding or

flowing from their point of entry. Those insects dwelling in dying

or dead stems or shoots of trees often eject fine sawdust or coarse

excelsiorlike wood shavings. Piles of this material on the ground

or streaks of it adhering to the bark pinpoint the location of the

insects' tunnel. Small pellets of frass (insect excrement) occur in

the vicinity of or beneath damage by defoliators. Several species of

defoliators construct protective artifacts such as bags, cases, or

webs that are distinctive. White frothy masses resembling spittle,

which occur on the twigs or branches of some trees, are excretions

of spittlebug nymphs. Careful parting of a mass will reveal the

insect within.

As insects develop, they grow larger by periodically shedding

their outer skin. Skins of the nymphs, larvae, or pupae, as well as

old eggshells, sometimes are present near the point of injury and

are useful in diagnosing the species of pest.
IDENTIFICATION KEY TO CONIFEROUS TREES

OF THE LAKE STATES

Coniferous trees in the Lake States include pine, spruce, fir,

tamarack, hemlock, yew, arborvitae (cedar), and juniper. Manypeople refer to them as ''evergreen trees'' because all except tamarack, which is deciduous, have green, needlelike, scalelike, or awlshaped leaves that persist for more than 1 year. Conifer seeds are

borne in cones, or on yew and juniper, in berrylike structures. Most

of the native Lake States conifers (except eastern redcedar)

occur most abundantly north of a line through central Minnesota,

central Wisconsin, and central lower Michigan. Some native and

introduced species are frequently planted throughout the Lake

States in forest or Christmas tree plantations, and as ornamentals

in parks, yards, and along roadsides.

Determining the species of conifer attacked is the first and most

helpful step in identifying injury, because a certain species may be

attacked by only one kind of wood borer, cone insect, etc. The following annotated key uses some simple characteristics of healthy

trees to help identify the 19 conifers most common to the Lake

States.

Beginning with key number J, select either leaves needlelike or

leaves scalelike or awl shaped.

To the right of your selection is another key number. Refer to

that number and repeat the selection process until the host tree

species is identified.

KEY NO. REFER TO KEY NO.:

1. Leaves needlelike 2

Leaves scalelike or awl shaped 21

2. Leaves in bundles or in clusters 3

Leaves not in bundles or in clusters 12

3. Leaves in bundles of two to five 4

Leaves numerous in cluster TAMARACK (plate 2, D)

Tamarack, Larix laricina (DuRoi) K. Koch,

or larch, occurs throughout the Lake States,

mostly in isolated stands on moist organic

soils such as bogs. It is commonly associated

with black spruce. An outstanding feature of

tamarack is its deciduous foliage that turns

yellow in autumn before falling.
KEY NO. REFER TO KEY NO.:

4. Leaves in bundles of two to three 5

Leaves in bundles of five EASTERN WHITE PINE

(plate 1, B)

Once the commonest pine in the Lake States,

eastern white pine, Pinus strobus L., is now

found in remnant stands of medium to large

trees, in scattered forest plantings, and occasionally as an ornamental. Young trees are

commonly under hardwoods.

5. Leaves 4 inches long or longer 6

Leaves less than 4 inches long 9

6. Leaves flexible, 5 to 11 inches long, not sharp to the

touch 7

Leaves rigid, 4 to 6 inches long, sharp to the touch,

large buds with silver scales AUSTRIAN PINE

Austrian pine, Pinus nigra Arnold, is an introduced European species planted occasionally

as an ornamental or for Christmas trees.

7. Leaves 5 to 11 inches long, two or three per cluster,

buds gray, bark brown 8

Leaves 5 to 6 inches long, two per cluster, buds brown,

bark tan, needle breaks when folded double

RED PINE (plate 1, A)

Red pine, Pinus resinosa Ait., sometimes

called Norway pine, is the predominant reforestation species in the Lake States. It occurs

abundantly in forest plantations in the boreal

forest zone of the Lake States and is commonly planted along roadsides.

8. PONDEROSA PINE

Ponderosa pine, Pinus ponderosa Laws., is an

introduced species from western North

America that is planted occasionally as an

ornamental.

9. Conifer is distinctly a tree 10

Conifer is a prostrate shrub MUGO PINE
KEY NO. REFER TO KEY NO.:

Bushy and seldom over 3 feet tall, mugo (or

mugho) pine, Pinus mugo Turra, is cultivated

as an ornamental throughout the Lake States.

10. Leaves % to II4 inches long; cones closed, curved, and

projecting toward tip of branch ; bark black 11

Leaves ll^ to 3 inches long, cone curved and projected

toward trunk, bark orange to red brown

SCOTCH PINE (plate 1, D)

Scotch pine, Pinus sylvestris L., is the most

common introduced European species in the

Lake States. It is planted widely for Christmas

trees and occasionally as an ornamental in

yards or along roadsides.

11. JACK PINE (plate 1, C)

Jack pine, Pinus banksiana Lamb., is abundant

on sandy soils in the boreal region of the Lake

States, especially in areas repeatedly burned.

Plantations and pure stands are common.

Other pines and hardwoods are sometimes

associated with jack pine.

12. Leaves four sided in cross section 13

Leaves not four sided in cross section, flattened 17

13. Leaves nearly square in cross section 14

Leaves diamond shaped in cross section, twig orange

from below, buds orange NORWAY SPRUCE

Norway spruce. Picea abies (L) Karst, is a

widely planted, introduced species used as an

ornamental and in windbreaks.

14. Leaves on sterile shoots (no cones) up to % inch long 15

Leaves on sterile shoots (no cones) longer than 1 inch,

rigid, tips sharp to the touch, commonly colored dull

bluish green, dark steel blue, or silvery white

BLUE SPRUCE (plate 2, B)

Blue spruce, Picea pungens Engelm., is introduced from western North America and commonly planted as an ornamental around homes

because of its attractive color.
KEY NO. REFER TO KEY NO.:

15. Leaves blunt and projecting evenly around shoot,

appearing like a bottle brush; buds short, dark

brown 16

Leaves pointed, crowded on upper surface because lower

leaves bend upward ; buds tan

WHITE SPRUCE (plate 2, A)

White spruce, Picea glauca (Moench) Voss,

grows commonly in the boreal zone of the

Lake States on various soils. It is often associated with black spruce, balsam fir, and

aspen. Sometimes grown in plantations and

along roads.

16. BLACK SPRUCE

Black spruce. Picea mariana (Mill.) B.S.P.,

occurs commonly in the boreal zone of the

Lake States on organic and mineral soils.

Usually the most common tree in bogs where

it may grow pure or with tamarack. Upland

black spruce commonly grows with balsam fir

and white spruce.

17. Leaves with a petiole 18

Leaves without petiole, dark brown above and silvery

white below ; buds tan and rounded ; flush round leaf

scar ; stem with pitch blisters _— BALSAM FIR (plate 2, C)

Balsam fir, Abies balsamea (L). Mill., occurs

commonly in the boreal zone of the Lake

States on podzolic soils and frequently grows

with white and black spruce and aspen.

18. Buds oval or rounded 19

Buds long, pointed, and dark brown; bracts on cones

extending beyond scales ; bark reddish brown

DOUGLAS-FIR

Douglas-fir, Pseudotsuga menziesii (Mirb.)

Franco, was introduced from western North

America principally for Christmas trees.

Some varieties are planted as ornamentals.

19. Leaves pea green below, a shrub, red berrylike fruit 20

Leaves not pea green below
KEY NO. REFER TO KEY NO.:

EASTERN HEMLOCK (plate 3, A)

Eastern hemlock, Tsuga canadensis (L.)

Carr., occurs mostly in the boreal regions of

Michigan and Wisconsin and in scattered

stands in northern Minnesota. It grows on

podzolic soils and is commonly found on moist

sites. Many horticultural varieties have been

cultivated for ornamental plantings.

20. CANADIAN YEW (plate 3, B)

Canadian yew, Taxus canadensis Marsh, is a

low shrub cultivated in various forms for

ornamental plantings.

21. Branchlets four angled or rounded in cross section;

blue, berrylike fruit 22

Branchlets flattened in fanlike sprays, scale leaves only

NORTHERN WHITE-CEDAR

(ARBORVITAE) (plate 3, C)

Northern white-cedar, Thuja occidentalis L.,

is known as ''cedar" in the wild state and

*'arborvitae" in horticulture. It occurs naturally throughout the boreal area of the Lake

States. At least 50 varieties are cultivated as

ornamentals.

22. Leaves awl shaped from 1/3 to 1/2 inch long, a shrub 23

Leaves mostly scalelike and tight to branchlets, about

%6 inch long

EASTERN REDCEDAR (JUNIPER) (plate 3, D)

Eastern redcedar, Juniperus virginiana L., or

juniper occurs naturally in the lower half of

the Lake States. There are many natural

varieties and races of this species and many

forms have been cultivated for ornamentals.

23. COMMON JUNIPER

Common juniper, Juniperus communis L., is a

low shrub that occurs in Minnesota commonly

in the wild state on limy soils, and throughout

the Lake States as an ornamental.
DEFOLIATING INSECTS

Sawflies

Sawflies are so called because the adult female has a saw-toothed

cutting structure used to make slits in needles in which she lays

her eggs singly or in rows (plate 16, A and B), The larvae, which

feed either singly or in groups called colonies, cause the injury.

Some species of sawflies are very destructive. These are principally the '"summer" sawflies—ones that may have more than

one generation per year and consume foliage of all ages. Such

sawflies can completely defoliate trees in a single season. When

this occurs, it will kill any of the Lake States coniferous species

except tamarack. Most of the less destructive species belong to

the "spring" sawfly group. These rarely kill trees directly because

they feed early in the spring before the new foliage has fully

appeared. Consequently, they eat only old foliage of earlier years,

so the trees are never completely denuded. If defoliated repeatedly,

or if under stress, such trees may succumb or become subject to

attacks by other insects or diseases.

Symptoms of injury are similar for most species of sawflies, so

larvae are needed to identify species (figs. 1, 2, and 3). An exception is the larch sawfly, which is easily identified because it is the

only sawfly that feeds on larch foliage.

The first symptom of typical sawfly injury is brown, dried-up

tufts of needles (plate 5, A) skeletonized by the young larvae.

These tufts may contain only a few skeletonized needles if the

sawfly feeds solitarily, or many needles if the sawflies feed in

colonies. Parts of needles missing or needles missing down to the

needle sheaths of pines (plate 5,5), or down to the twig on other

conifers are characteristic signs of feeding by older larvae.

Branches may be completely bare later in the season after injured

needles and sheaths fall oiï. Single branches or entire trees may

be completely stripped of old or both old and new foliage when

sawflies are numerous (plate 4, C). The bark of twigs in the

feeding zone may be nibbled also.

Sawfly defoliation can also be confused with defoliation by a few

other insects, especially the pine tussock moth (plate 6, C) and the

hemlock looper (plate 4, A). The skeletonizing done by the young

sawflies (plate 5, A) is distinctive, but skeletonized needles remain

intact for only a few weeks. Signs such as frass, cocoons (fig. 4),

or cast larval skins are useful and sometimes necessary for positive identification. The full-grown larva (fig. 5) of most species

of sawflies attains a length of % to 1 inch.
FIGURE 1.—Conifer sawfly larvae coloration and feeding periods.

NAME LARVAL DESCRIPTION

A. Redheaded pine sawfly, Neodi- Head: Reddish brown.

prion lecontei (Fitch), p. 16. Body: Yellow with rows of black

spots.

B. White pine sawfly, Neodiprion Head:

pinetum (Norton), p. 16. Body:

Black.

Pale yellow with rows of

black spots.

C. Redheaded jack pine sawfly. Neo- Head:

diprion rugifrons Middleton, p. Body:

17.

Reddish brown.

White with black spots and

stripes, seven pairs of prolegs.

D. Brownheaded jack pine sawfly. Head:

Neodiprion duhiosus Schedl, p. Body:

17.

Reddish brown.

Yellow with black spots and

stripes, seven pairs of prolegs.

E. A pine sawfly, Neodiprion mau- Head:

rus Rohwer, p. 17. Body:

Black.

Yellow green with darkgreen stripes and squarish

spots, seven pairs of prolegs.

F. Jack pine sawfly, Neodiprion Head:

pratti banksianae, Rohwer, p. 18. Body:

G. Swaine jack pine sawfly, Neodi- Head:

prion swainei Middleton, p. 19. Body:

Black.

Yellow green with two pale

green stripes and a third

that tends to break into

spots.

Brown.

Yellow green with two faint

stripes and faint spots.

10
LARVAL FEEDING PERIOD

APR MAY JUN JUL AUG SEP

11
FIGURE 2.—Conifer sawfly larvae and feeding periods.

NAME LARVAL DESCRIPTION

A. A pine sawfly, Neodiprion nigro- Head: Reddish brown to black.

scutum Middleton, p. 19. Body: Yellow green with two

broad, dark-green stripes.

B. A pine sawfly, Neodiprion compar

(Leach), p. 19.

Head: Dark brown with maskmarked face.

Body: Yellow green with two

broad, dark-green stripes.

C. Abbott^s sawfly, Neodiprion abhottii (Leach), p. 20.

D. Nursery pine sawfly, Gilpinia

frutetorum (F.), p. 20.

Head: Black with light spot on

front.

Body: Yellow green with two

broad, dark-green stripes.

Head: Reddish brown with black

triangular marking on front.

Body: Light green with green

stripes.

E. Red pine sawfly, Neodiprion

nanulus nanulus, Schedl, p. 21.

Head: Black.

Body: Gray green with green

stripes of various shades.

F, European pine sawfly, Neodiprion

sertifer (Geoff.), p. 21.

Head : Black.

Body: Gray green with light and

dark-green stripes.

G. Balsam fir sawfly, Neodiprion

abietis (Harris), p. 21.

Head : Dark brown to black.

Body: Dull green with dark-green

stripes.

12
FULL-GROWN LARVA

SAME AS ABOVE

SAME AS ABOVE

LARVAL FEEDING PERIOD

APR MAY JUN JUL AUG SEP

13
FIGURE 3.—Conifer sawfly larvae and feeding periods.

NAME LARVAL DESCRIPTION

A. Introduced pine sawfly, Diprion

similis Hartig, p. 21.

Head: Black.

Body: Yellow green with black

stripe above yellow and

white spots.

B, European spruce sawfly, Diprion

hercyniae Hartig, p. 22.

Head: Yellow brown with black

marks.

Body: Dark green with five white

lines.

C. Greenheaded spruce sawfly, Pikonema dimmockii (Cresson), p. 22.

Head: Green.

Body: Dark green with light-green

stripe.

D. Yellowheaded spruce sawfly, Pi22.

Head : Yellow to reddish brown and

mottled.

Body: Waxy, olive green with six

stripes.

E. Larch sawfly, Pristiphora erichsonii (Hartig, p. 23.

Head: Black.

Body: Dull-gray green above, paler

green below.

F. Arborvitae sawfly, Monoctenus Head: Reddish brown.

juniperinus MacG., p. 23. Body: Yellow with light-green

stripe.

G. Eastern cedar sawfly, Monocienws Head: Light brown.

melliceps (Cresson), p. 23. Body: Dull green with dark-green

stripes.

14
FULL-GROWN LARVA LARVAL FEEDING PERIOD

APR MAY JUN JUL AUG SEP

u

M

15
Redheaded pine sawfly Neodiprion lecontei (Fitch)

This is the most destructive pine sawfly in the Lake States. It

attacks several pines of all sizes, but prefers jack and red pine,

especially in plantations or in windbreaks less than 15 feet tall.

The larvae feed in colonies. Their defoliation is typical for colonial

savs^flies, but the old foliage is eaten first, then the new foliage,

especially vi^here a second or partial second generation occurs.

Tufts of dried skeletonized needles are first formed, then needles

are consumed down to the needle sheaths. Some partially consumed

needles, however, are left on the shoots (plate 4, C). Tree mortality

often occurs in pockets or along edges of stands, particularly where

trees are under stress.

Look for the larvae between mid-June and late July and between mid-August and late September. The full-grown larva has a

reddish-brown head ; the body is yellow with six rows of irregular

square black spots (fig. 1).

White pine sawfly Neodiprion pinetum (Norton)

This insect seldom causes economic loss, but it can be destructive. It prefers eastern white pine, but sometimes it feeds on red

and mugo pines. It feeds in colonies on both new and old foliage.

F-607932

FIGURE 4.—Sawfly cocoons.

16
and occasionally kills trees by complete defoliation. Defoliation is

typical of colonial sawflies (plates 5, B and 4, C) ; tufts of needles

are first left, then needles are eaten down to the needle sheaths.

Look for the larvae between mid-June and late July and between

mid-August and late September. The fully grown larva has a black

head; the body is white to pale yellow with four rows of nearly

square black spots (fig. 1).

Redheaded jack pine sawfly Neodiprion rugifrons Middleton

This sawfly is a serious pest on pole-size jack pine in **long

summer" years, when it has two generations. In one-generation

years, only the old foliage is consumed and trees are seldom killed

even if heavily defoliated. In two-generation years, both the old

and new foliage are consumed and trees die if larvae are abundant

enough to strip them completely. The larvae are strongly gregarious and feed in large colonies—often of 125 or more. Defoliation

is typical of colonial sawflies, but the location of the injury varies

depending on whether there are one or two generations (plates

5,ßand4, C).

Look for the larvae of the first generation between early June

and mid-July, and the second generation between early August and

mid-September. The full-grown larva has a reddish-brown head;

the body is white with black stripes and spots (fig. 1). The markings are nearly the same for N, dubiosus, but the body color differs.

Brownheaded jack pine sawfly Neodiprion duhiosus Schedl

This sawfly prefers jack pine for egg laying, but larvae may

feed on red pine growing with jack pine. Its known range is

northern Wisconsin and adjacent upper Michigan.

This species severely defoliates windbreak trees on occasion. The

larvae are colonial, but full-grown larvae are atypical because they

tend to feed in loose aggregations (plate 5, ß).

Look for the larvae between late June and late July. The fullgrown larva has a reddish-brown head; the body is yellow with

black stripes and spots (fig. 1). The markings are nearly the same

for N. rugifrons, but the body color differs.

A pine sawfly Neodiprion maurus Rohwer

Seldom a serious pest, this sawfly feeds on jack pine in Wisconsin, Minnesota, and the Upper Peninsula of Michigan. The larvae

feed in colonies and consume mostly old foliage. The defoliation

pattern is typical of colonial sawflies feeding on old foliage (plate

5, ß). Young larvae skeletonize the needles leaving tufts of dry

needles. The older larvae devour the needles down to the sheaths.

17
Look for the larva from late May to early July. The full-grown

larva has a black head ; the body is yellow green with dark-green

stripes and squarish spots (fig. 1).

F-508B25

FIGURE 5.—Sawfly larvae.

Jack pine sawfly Neodiprion pratti banksianae Rohwer

This insect occurs throughout the range of jack pine in the

Lake States. It prefers jack pine but will feed on red and Scotch

pine when these hosts are growing near jack pine. Occasionally it

becomes abundant and causes moderate defoliation. Open-grown,

even-aged stands are preferred, but the trees of all sizes are vul18
nerable to attack. Young trees seldom die even if heavily defoliated

because the sawfly feeds only on the old needles. Old trees, hov^-

ever, sometimes die after two or more heavy defoliations because

they weaken and put on insufficient new growth to sustain them.

The defoliation pattern is typical of colonial sawflies feeding on

old foliage (plates 4, J?, and 5, B). Look for the larvae from early

May to late June. The full-grown larva has a black head ; the body

is yellow green with two pale greenish-gray stripes and a third

darker stripe that tends to break up into spots (fig. 1).

Swaine jack pine sawfly Neodiprion swainei Middleton

This insect occurs throughout the range of jack pine in the Lake

States and is occasionally destructive. It lays eggs only on jack pine

as far as known, but the larvae occasionally feed on red, eastern

white, and Scotch pine when these trees are grown with jack pine.

The female sawñy lays 1 to 6 eggs per needle in clusters of 30

to 80 eggs. The young larvae typically skeletonize the needles first

and older larvae consume entire needles down to the fascicles

(plate 5, B). Old foliage, however, is preferred, and new foliage

is only nibbled on, producing ragged injury to the new shoots.

Partially defoliated trees may dieback at the top.

Look for the larvae from late June to mid-August. The full

grown larva has a brown head ; the body has two faint stripes and

rows of faint spots (fig. 1).

A pine sawfly Neodiprion nigroscutum Middleton

Seldom abundant, this sawfly feeds mostly on jack pine foliage.

Highest populations occur on windbreaks ; scattered colonies occur

in natural stands. The larvae feed singly or in small colonies of

rarely more than 10 insects, mainly because eggs are laid in small

clusters on only one to three needles. Larvae eat both old and new

foliage like the more typical colonial sawflies (plates 4, C, and

5, ß), except fewer needles are consumed because there are fewer

larvae.

Look for the larvae between late May and early July and between

early August and early September. The full-grown larva (flg. 2)

has a reddish-brown to black head ; the body is yellow green with

two broad dark-green stripes. The markings on this insect are

almost the same as those of N, abhotii and N. compar. The latter

two, however, have a white spot on the front of the head.

A pine sawfly Neodiprion compar (Leach)

This poorly known sawfly has never been a serious defoliator.

It prefers jack pine but will feed on red pine. Because it commonly

19
feeds alone but is also found in colonies, damage can be either of

the solitary or colonial sawfly type (plates 7, D, and 5, 5).

Look for the larva from late June to late July. The full-grown

larva (fig. 2) has a dark-brown head with a prominent white spot,

giving it the appearance of being masked ; the body is yellow green

with two broad, dark-green stripes. The body markings on this

insect are almost the same as those of N, abbottii and N. nigroscutum.

Abbott's sawfly Neodiprion abbottii (Leach)

Reported from Wisconsin, this sawñy feeds on all the hard pines.

It has not been abundant in the Lake States, but it is potentially

destructive.

The female sawfly lays 15 to 20 eggs close together on a single

needle. The young larvae feed gregariously on surrounding needles

but seldom consume this needle, so it is a distinctive sign for

identifying this species in the field (plate 5, Z?).

The early larval defoliation, which is manifest as tufts of skeletonized needles, is typical of these and other colonial sawflies.

Because its larval colonies are small, however, and seldom have

more than 25 insects, the tufts are smaller. The older larvae tend

to feed singly and thus defoliate small isolated patches of needles.

Look for the larvae from mid-June to the end of July. The fullgrown larva (fig. 2) has a black head with a faint light spot on

the front; the body is yellow green with two, broad, dark-green

stripes. The markings on this insect are virtually the same for

N. nigroscutum and N, compar, N, nigroscutum differs by having

a reddish brown to black head without a frontal spot ; N, compar

differs by having a dark-brown head and an additional white

marking on the lower part of the face.

Nursery pine sawfly Gilpinia frutetorum (F.)

This sawfly occasionally causes heavy defoliation in red and

Scotch pine stands. It is sometimes called the solitary pine sawfly

because it feeds singly. Light infestations are not readily detected

because the larvae blend well with the foliage. Excrement or green

needle fragments on the ground beneath infested trees commonly

betray their presence before they are seen. Defoliation takes the

form of missing needles in small patches (as in plate 7, D) that

coalesce when larvae are abundant. Larvae eat both old and new

foliage, especially if there is a second generation.

Look for the larvae between early June and early July and between late July and early September. The second to the last larval

stage (fig. 2) has a reddish-brown head with a black triangular

marking on the front; the body is light green with a dark and

20
light stripe. The full-grown, last-stage larva is marked the same

but lighter.

Red pine sawfly Neodiprion nanulus nanulus Schedl

This insect occasionally becomes abundant in red and jack pine

stands. It attacks trees of all sizes in open and closed stands, but

rarely are they injured permanently because the sawfly feeds only

on old needles. The larvae feed in colonies, but the injury is

atypical of colonial sawflies. Injury differs because the larvae

consume just about three-fourths of the needles, leaving needle

stubs % to 114 inches long on red pine and ^4 to V3 inch long on

jack pine (plate 5, C). This sawfly can be identified from these

stubs that remain on the branches throughout the year.

Look for the larvae from early May to mid-June. The full-grown

larva has a black head; the body is dull gray green with stripes

of various shades of green (fig. 2).

European pine sawfly Neodiprion sertifer (Geoff.)

This sawfly was introduced in eastern North America from

Europe and is now present in Michigan and Wisconsin. Commonly

abundant on pines of all sizes, it causes heavy defoliation, but

because it feeds only on old needles, trees seldom die—even after

repeated defoliation. It prefers Scotch pine but will attack red,

jack, and sometimes other pines.

The defoliation pattern is typical of colonial sawflies feeding on

all foliage (plates 5, B, and 4, B), Look for the larvae from early

May to mid-June. The full-grown larva has a black head ; the body

is gray green with several light- and dark-green stripes that tend

to break up into spots (fig. 2).

Balsam fir sawfly Neodiprion ahietis (Harris)

This sawfly is occasionally destructive to ornamentals and forest

stands of balsam fir. This species, or perhaps a closely related

species, sometimes attacks spruce. Outbreaks have occurred but

they have neither been extensive nor serious. The larvae feed in

colonies and consume old foliage first and new foliage later. The

defoliation pattern is typical of colonial sawflies ( plate 5, JB).

Look for the larvae between early June and early August. The

full-grown larva (flg. 2) has a dark-brown to black head; the body

is dull green with dark-green stripes. The cocoons are generally

spun on the foliage.

Introduced pine sawfly Diprion similis Hartig

This insect was introduced in eastern North America and has

since spread throughout most of the Lake States coniferous forests.

21
Its favorite host is eastern white pine, but occasionally it injures

Scotch, jack, and red pine. It attacks trees of all sizes, preferring

ornamental, nursery, and plantation trees. The young larvae feed

in colonies ; the older ones feed alone. Consequently, early defoliation manifested as dried needle tufts is typical of colonial sav^flies

(plate 5, B), and late defoliation is more like that of solitary

saw^flies (plate 7, D). Defoliation appears as missing needles that

coalesce into larger patches v^hen larvae are abundant. Firstgeneration larvae feed on old foliage; second-generation larvae

feed on old and nev^ foliage.

Look for the larvae betv^een late May and early July and between

late July and early September. The full-grown larva has a black

head; the body is yellow green with a black double stripe above

and numerous yellow and white spots (fig. 3). The markings are

unique and easily distinguished from those of other sawflies on

conifers. The egg cluster of this species is distinctive because it is

covered with a mucilaginous substance.

European spruce sawfly Diprion hercyniae Hartig

Introduced from Europe, this sawñy has caused extensive defoliation and mortality in eastern North America, and has been

detected in Wisconsin. It feeds on white, black, and other spruces

of all sizes. It prefers old foliage but will consume either old or

new when the larvae are nearly mature. Injury is similar to that

of solitary sawñies (plate 7, D), Heavily infested trees are commonly completely defoliated and killed.

Look for the larvae between mid-May and late June and between

mid-July and late August. The full-grown larva has a yellowbrown head with black marks on the front and sides ; the body is

dark green (fig. 2). Five narrow white lines run the length of the

body in all stages except the last.

Greenheaded spruce sawfly Pikonetna dimmockii (Cresson)

An uncommon insect, this sawfly has never caused serious defoliation. It is known in Ontario and may occur in the Lake States.

It feeds on white, black, and blue spruce.

Look for the larvae from early June to early August. The fullgrown larva has a green head ; the body is striped light and dark

green (fig. 3).

Yellowheaded spruce sawfly Pikonema alaskensis (Rohwer)

When abundant, this sawfly is very destructive to white, black,

and blue spruce. It prefers open-grown trees. Most dense stands,

22
natural or planted, typically remain free from attack. Damage is

most severe on windbreaks, ornamentals, nursery seedlings, young

plantations, and trees in naturally regenerated cutover areas. The

larvae are semicolonial—they feed in loose clusters on the new

foliage first and then on the old foliage. Tips of infested branches

appear ragged (plate 7, D) and contain brown needle stubs. Trees

that are completely defoliated by midsummer die ; those with some

foliage remaining may live, but usually lose some branches.

Look for the larvae from late May to mid-July. The full-grown

larva has a yellow to reddish-brown head that is mottled ; the body

is waxy, olive green, with six gray-green stripes of various widths

(fig. 3).

Larch sawfly Pristiphora erichsonii (Hartig)

This is one of the most destructive sawflies in the Lake States.

It kills some tamarack stands yearly, especially in Minnesota.

Tamarack, however, because it is deciduous and refoliates every

year anyway, does not die readily from the effects of defoliation.

Nonetheless, even apparently vigorous trees will die after 6 to 8

years of moderate defoliation. Less thrifty trees may succumb

after only 3 or 4 consecutive years of attack. The larvae feed in

colonies (as in plate 5, B) but even then they are difficult to see

because they are the same color as the foliage. Before defoliation

is readily noticed, frass and needle remnants beneath the tree

betray the insect's presence. Trees may be completely defoliated

by the time the larvae are fully grown.

This is the only sawfly in the Lake States that lays its eggs in

the new shoot twigs instead of the needles (plate 31, A). The

injured shoots become curved or curled as they grow (plate 31, B),

This so-called "pigtailing'' is a good sign of an impending infestation before the larvae appear.

Look for the larvae from early June to late September. Larvae

vary widely in size during this period. The larva (fig. 3) has a

black head ; the body is dull gray-green above, paler below.

Arborvitae sawfly Monoctenus juniperinus MacG.

This sawfly is an occasional pest of ornamental juniper and

aborvitae. The larva feeds singly and destroys small groups of

needles. Look for the larvae during June and July. The full-grown

larva has a reddish-brown head ; the body is yellow with a lightgreen stripe (fig. 3).

Eastern cedar sawfly Monoctenus melliceps (Cresson)

This sawfly occasionally causes minor defoliation on juniper and

arborvitae and is usually a pest on ornamentals. The larvae feed

23
singly, destroying leaves partly to completely. Look for the larvae

during June and July. The full-grown larva has a light-brow^n

head ; the body is dull green with darker-green stripes (fig. 3).

Leaf Beetles

Adult leaf beetles are foliage feeders. Outbreaks are seldom

severe and are usually localized. Because these beetles feed mostly

on new foliage, few trees die. Usually the trees are weakened and

lose some groAvth.

Pine chafer Anómala oblivia Horn

The pine chafer sometimes becomes abundant and defoliates sapling pines in natural and planted stands in Michigan. It prefers

jack pine but commonly attacks red, eastern white, and Scotch

pine.

FIGURE 6.—Pine chafer adult.

F-621434

The adult beetles gnaw the side of the needles through the fascicles. Feeding usually stops before the needle is severed, causing

it to droop (plate Q,A). New needles are injured in June and July

before full development; old needles are eaten only after most of

the new ones are destroyed. Afflicted needles turn brown so from

24
a distance heavily infested trees appear scorched. The portion of

the needle above the injury later falls off, leaving an irregular

needle stub. Although the injury may superficially resemble "needle blight" midge (p. 51), needle droop (p. 86), or the pine needle

sheathminer (p. 34), it differs from the foregoing pests in that it

occurs earlier in the year, it lacks v^ebbing, and the beetles gnaw

through the fascicle.

Look for the adult beetles, which feed during the daytime, during

June and July. They are 14 to % inch long; the female (fig. 6) is

tan or light brown ; the male is dark brown.

Pine chrysomelid Glyptoscelis puhescens (Fab.)

This beetle occasionally becomes abundant in pine stands and

causes heavy defoliation and growth loss. It prefers eastern white,

red, jack, and Scotch pine. Spruces and hemlock are occasional

hosts.

On pines, the male cones (plate 53, A) are destroyed by early

feeding. Later damage is to clusters of very young developing needles that are eaten down to the needle sheath (plate 7, B), Older

needles are notched at various intervals along their lengths (plate

7, A). These turn brown later and break off. Notched needles on

pine are diagnostic for this insect. The needle damage resembles

that of the adult black vine weevil and strawberry root weevil

(plate 6, B), but they do not attack pine. In the spring look for the

small adult beetles, which are brown with a brassy sheen and covered with short hairs.

Grasshoppers and Walkingsticks

Conifers are not the normal host plants for grasshoppers and

walkingsticks—at least in the Lake States. Both, however, feed on

conifers when their normal food source is depleted.

Grasshoppers Melanoplus spp.

Both nymphs and adults of grasshoppers sometimes defoliate

conifers. Seedlings and windbreak trees are most susceptable to

injury, especially if growing adjacent to fields of small grains.

Grasshoppers may destroy seedlings but usually injure older trees

only in the lower few whorls.

Clusters of needles chewed off near the middle or notched

and broken over are symptoms of attack (plate 6, Z)). Bark of the

young stems may be nibbled. Most injury occurs in late summer

after grain fields are harvested.

25
Walkingstick Diapheromera fenwrata (Say)

The walkingstick rarely attacks conifers. The adult walkingstick, however, sometimes moves to and feeds on conifers growing

beneath or near hardwoods—their normal hosts. They have been

found feeding on Scotch pine and eastern white pine. The latter is

commonly planted beneath hardwoods.

Needles that are partly chewed oif give the tree a ragged appearance, the main symptom of attack. This damage is indistinguishable from defoliation of most solitary sawflies (as plate 7, D). The

adult is thin and sticklike. Walkingstick eggs, which are small and

seedlike, are laid on the soil beneath injured trees and indicate the

presence of this insect. Finding these eggs requires careful sifting

of the soil.

Webless Moths

Webless moths—insects that produce little or no webbing except

when spinning their cocoons—defoliate conifers and include loopers, tussock moths, and the giant silkworms.

Loopers are so called because the larvae "loop" the midportion of

their bodies while walking. This they must do because they have

only two or three pairs of prolegs on the abdomen instead of the

usual five or mroe of most caterpillars (fig. 7). Tussock moths are

so called because the larvae are tufted with short brushes and long

F-B21B06

FIGURE 7.—Looper larva.

26
pencils of hairs. Giant silkworms are a group of large moths whose

larvae usually feed on hardwoods ; one species is occasionally found

on pine.

Hemlock looper Lamhdina fiscellaria fiscellaria (Guen.)

The hemlock looper mounts severe and prolonged outbreaks in

mature and overmature stands. It prefers eastern hemlock and

balsam fir, but will attack a wide variety of conifers and hardwoods.

Browning of the foliage in July is a prominent diagnostic sign

of an attack. This coloring is due to the browning of the remains

of needles partly devoured by the larvae. Young larvae feed on current year's foliage and older larvae on the old foliage. Nearly all

needles may be damaged or devoured on a severely infested branch

or tree (plate 4, A). Trees that lose more than 90 percent of their

foliage die the folowing winter. In a typical outbreak small patches

of heavily infested trees are surrounded by untouched stands.

The larvae are typical loopers (as fig. 7), and are mottled with

colors ranging from greenish yellow to brown to black.

Pine tussock moth Dasychira plagíala (Walker)

The pine tussock moth is a serious pest that commonly attacks

large acreages of sapling and pole-sized conifers, especially in

northern Wisconsin. It prefers jack pine but attacks red and eastern white pine, too. Spruces and firs are occasional hosts.

The young larvae feed in the male cones (plate 53, A). The feeding damage done by the older larvae is similar to that of the solitary sawflies but generally more ragged (plate 6, C). New and old

foliage is eaten down to the needle sheath so that small stubs remain on the twigs. When larvae are abundant, they completely

defoliate and kill the trees.

The larvae, cocoons, or egg masses on the foliage are easily identified. The larva is a gray brown, hairy caterpillar (fig. 8) up to

11/^ inches long, with four tufts of grayish hairs on the back. Graybrown cocoons (plate 6, C), made of silk and hairs, and whitish

egg masses are attached to the needles.

Imperial moth Eacles imperialis (Drury)

Usually a rare insect, the larvae of this variety of imperial moth

may become locally destructive. They defoliate eastern white, red,

and jack pine and sometimes juniper, preferring open-grown saplings. The damage is nearly typical of solitary defoliators—needles

of all ages are removed in patches, but mostly on the noth side of

the tree. The damage resembles that of the pine tussock moth and

some sawflies (plates 6, C, and 7, D),

27
The larvae is needed for positive damage identification. It is at

least 2 inches long when fully grown, pale to dark green with

reddish-purple markings. The body is covered with short stiff

hairs; there are spines on the second and third abdominal segments.

F-523402

FIGURE 8.—Pine tussock moth larva.

Bagworms, Tubeworms, and Webworms

This group includes a heterogenous array of defoliators that

construct conspicious concealments (bags, tubes, or webs) from

which they feed. Most of these are moths, but certain sawflies

(Acantholyda spp., Cephalcia spp.) are also included here because

28
their habits are unlike typical sawflies, and their nests are similar

to and easily confused with the true webworms. All are injurious

in the larval stages.

Bagworm Thyridopteryx ephemeraeformis (Haw.)

The bagworm is a serious defoliator of sapling trees and shrubs

in urban areas. It also attacks forest trees but seldom is economically important. It is uncommon in the Lake States. The bagworm

prefers arborvitae but commonly attacks juniper. Other conifers

are seldom attacked. This pest also feeds on hardwoods.

The conspicious bags are diagnostic for this species (plate 10,

B). They are 1% to 2 inches long and consist of a silken case covered with pieces of needles. They differ slightly in appearance

depending on the host tree. Needles are stripped from trees by the

larvae, usually from the tree top down. Trees die when heavily

defoliated. Shoot flagging also occurs because of the tight silken

band around the twig with which the larva attaches the bag. Bags

may remain attached to the tree for a year or more after they are

abandoned.

Pine tube moth Argyrotaenia pinatubana (Kft.)

The pine tube moth is occasionally abundant on eastern white

pine of all sizes, but it is not economically important. At worst the

trees are unsightly because of the webbed tubes.

The cylindrical tubes made from foliage and silk are diagnostic

for this insect. The tubes are comprised of 5 to 20 needles bundled

together to form a chamber (plate 10, C). Young larvae mine the

needles. The older ones feed on the tips of the needles, keeping them

all flush on the free end. When the tube has been shortened to about

1 inch, the larva abandons it and makes a new one. Tubes are

formed all summer because there are two generations each year.

Juniper webworm Dichom^eris m^arginella (D. & S.)

The juniper webworm is a pest introduced from Europe. It is

sometimes a serious defoliator of nursery seedlings and sapling

ornamentals. It feeds on all varieties of junipers but prefers Juniperns squamata var. Meyeri, SL dense shrub.

The young larvae are needle miners (plate 9, A). The older larvae live in nests, which are diagnostic for this species. Nests are 2

to 3 inches long and consist of twigs webbed together with threads

spun by several small, light-brown larvae (plate 11, A and B). The

larvae feed on foliage in and near the nest. Hundreds of nests may

occur on the same tree. Look for the larvae in the nests from April

to early June and in September.

29
Pine webworm Tetralopha robustella ZelL

The pine webworm occasionally becomes serious on pine seedlings and saplings ; it is of no economic importance on larger trees.

It prefers jack, red, eastern white, and Austrian pines.

The conspicuous elongated or globular mass of excrement held

together by silk and honeycombed with silken tubes is evidence of

this insect (plates 10, D, and 11, D), This nest may contain 25 or

more larvae and be up to 6 inches long. The larvae skeletonize or

chew off the needles surrounding the nest. The nest and damage

can easily be confused with those of the nest-making sawflies,

Acantholyda and Cephalcia. However, the yellowish-brown striped

webworm larvae are readily distinguished from the sawfly larvae

by its eight pairs of legs and no spines. The sawflies have only three

pairs of legs and a pair of short spines on the sides of the last

segment.

Pine false webworm Acantholyda erythrocephala (L.)

The pine false webworm is an introduced pest that is now the

commonest nest-building sawfly in the Lake States. It has never

been a severe pest, however, even when locally abundant. It favors

eastern white pine but will feed on red, Scotch, and other pines.

Conspicious nests or shelters up to 6 inches long are formed of

loose silk and filled with much excrement (plate 11, C). Look for

larvae living singly or in small colonies in the nests. The nests are

similar to those of the pine webworm and the nesting pine sawfly.

The larvae are distinctive. The A, erythrocephala has three pairs

of legs, a yellow head with brown spots, green body, and purplishred stripes.

Nesting pine sawfly Acantholyda zappei (Rohwer)

The nesting pine sawfly (A. zappei) and other nesting sawflies

(Cephalcia spp.) are seldom found on conifers in the Lake States.

They are usually economically unimportant. A. zeppei prefers jack,

red, and Austrian pines, Cephalcia spp. feed on most conifers.

The frass-filled nests of A. zappei are similar to those of the pine

false webworm and pine webworm (plate 11, C and D) but smaller

and usually solitary (plate 10, D). The larva has three pairs of

legs, a brown head, and a green body.

Budworm Moths

Budworms, the larvae of certain moths, are so called because

when young they bore into and destroy the buds of conifers. Older

larvae feed on the foliage. There are three destructive and two less

30
important species in the Lake States. All species do similar damage, but they are easily separated by their hosts and their different

larvae.

Spruce budworm Choristoneura fumiferana (Clemens)

This insect is the most widely distributed forest defoliator in

eastern North America. It has mounted severe outbreaks at frequent intervals during the past 150 years and killed millions of

trees. Mature and overmature trees are most susceptible to attack

but trees of all sizes, including seedlings, are injured or killed during an outbreak. Balsam fir and white spruce are the preferred

hosts in the Lake States, especially in the boreal forests of Minnesota. The insect also feeds on other spruces, larch, and pines if they

are growing along with the preferred hosts.

FIGURE 9.—Budworm pupal

case.

F-521435

Symptoms of an outbreak are heavily defoliated, dead, dying,

and top-killed trees. Browning or reddish foliage is loosely webbed

onto the shoots by larval threads. This browning foliage consists

of remnants of needles mined by young larvae and partly consumed

needles fed on by the older larvae (plate 8, A). Besides the needle

remnants, the webbing contains frass, cast larval skins, pupal cases

(fig 9), and other debris that are useful for identification when the

81
larvae are absent. The young larvae also mine the buds (plate 29,

D) and male flowers (plate 53, A).

Young larvae are light brov^n v^ith black heads ; mature ones are

gray-brov^n with small cream-colored spots along the sides (plate

8, A). They resemble larvae of the jack pine budworm on pine, but

they are readily distinguished by their different hosts.

Jack pine budworm Choristoneura pinus Freeman

This pest is the most important defoliator of jack pine in the

Lake States. Large and small outbreaks occur frequently. The larvae also feed on red, Scotch, and eastern white pine if growing

beneath or adjacent to infested jack pine. They attack jack pines of

all sizes, but especially ones with abundant male flowers (plate

53, A).

Symptoms of an outbreak are heavily defoliated, dead, and dying

trees. Browning or reddish foilage, loosely webbed onto the shoots,

consists mostly of partly consumed needle remnants (plate 8, B).

The webbing also contains frass, cast larval skins, pupal cases (fig.

9), and other debris useful for identification when larvae are absent. The young larvae mine fascicles of new needles. After the

supply of new foliage has diminished, the large larvae feed on the

older needles.

Young larvae are brown with black heads; mature ones are

reddish brown with small cream-colored spots along the sides.

They resemble larvae of the spruce budworm on spruce and balsam

fir (plate 8, A) but can be readily distinguished by their different

hosts.

Eastern blackheaded budworm Acleris variana (Fern.)

This insect attacks trees of all ages and when conditions are

favorable, it increases in numbers sufficiently to kill them. Sometimes there are large-scale outbreaks in mature and overmature

forests. It prefers balsam fir but attacks white and black spruce

during epidemics.

Symptoms of its injury are typical for budworms. Trees are

defoliated, the top is killed, or they die, depending on severity of

attack. Partially eaten needles, which are reddish, cling to twigs

by loose webbing similar to that of the spruce budworm (plate

8, A). Larvae prefer new foliage but will feed on old and mine the

buds. The webbing also contains frass, cast larval skins, pupal

cases (fig. 9), and other debris that are useful for identification

when larvae are absent.

The damage of the blackheaded budworm (plate 8, A) is similar

to that of the spruce budworm on the same hosts. The larvae, how32
ever, are different and should be used for identification. The immature larva of the blackheaded budworm is pale yellow with a black

head ; the full-grown one is yellow green with a light-brown head.

A tip moth Tortrix pallorana (Rob.)

This insect is rare but sometimes becomes abundant locally. It

prefers eastern white pine but will attack red, jack, and Scotch

pine. Young saplings 3 to 7 years old are most commonly attacked.

The larva of this insect webs two or more new shoots together

before they are fully expanded. It eats only part of the needles

within the web and tunnels into and kills one or more of the shoots.

These dying shoots droop in mid-May, (plate 30, A) but webbing

is present. The injury to the needles from feeding (plate 8, C) resembles that of the jack pine budworm, but the Tortrix larva is

yellow brown in contrast to the brown or reddish-brown budworm

larva.

Needle Miners

The true needle miners are small moths that excavate tunnels

within needles during their entire larval period. True needle

miners are identified by the presence of a few to several mined

needles adjacent to one another. Injured needles are yellowish and

when held up to the light they appear hollow. Presence of a pupal

case in a mine is also diagnostic.

The larvae of certain other moths cause insignificant damage as

needle miners during their early stages. However, they are more

noteworthy by the damage they do later by boring in expanding

buds and cones, or by direct defoliation, and are therefore discussed

under those damage categories. Representative species include the

spruce budworm (p. 31), the jack pine budworm (p. 32), the spruce

coneworm (p. 83), the juniper webworm (p. 29), and the pine

tube moth (p. 29).

Spruce leafminer Epinotia nanana (Treit.)

This is a needle miner common on most species of spruce. It occasionally causes heavy defoliation in forests but is more commonly

a pest of ornamentals. Look for four to eight needles mined from

the base to the apex. Some loose silk webbing is spun among the

mined and adjacent needles (plate 9, C). Most of the insect's frass

is accumulated around a silken tube within which the insect pupates. Characteristically for this species, some frass is present

inside the needle mines. The small larva is dirty white to reddish

and has a black head.

33
Spruce neediemîner Taniva albolineana (Kit.)

This species will attack forest-grown spruce in the Lake States

but it is mostly a pest of ornamentals. Look for numerous mined

needles along the shoot that are densely webbed together at their

bases. The webbing is heavily filled with frass (plate 9, B). Several

larvae usually live together in the webbing. Mined needles contain

no frass but may be severed at their bases and entangled in the

webbing. The small larva is greenish to greenish brown with a

yellow-brown head.

Spruce leafminer Pulicalvaria piceaella (Kit.)

This miner is common on spruces but it is more often a pest of

ornamentals than forest stands. Look for four to six old needles

in a cluster, each needle mined from the base to the top. A loose

web is spun between mined and undamaged adjacent needles (as

plate 9, C). Characteristically, there is no frass in the mines and

only a few frass pellets adhere to the webs. The small larva is reddish to light brown with a light-brown head.

Pine needleminer Exoteleia pinifoliella (Chamb.)

This insect has been collected from red, Scotch, and other pines

besides jack pine, which it prefers. It occasionally becomes sufficiently abundant to be a threat to jack pine. Continuous severe

attacks over a period of years will destroy its hosts. It attacks polesize trees most often.

Usally new needles are attacked first, old ones later. Each pine

needleminer larva destroys only three needles that are usually

close together. The mined portion of the needles turns yellow (plate

7,C). Look for yellow needles that hang on overwinter and break

OÎÏ the next year. Old infested shoots look ragged and discolored

because of the remaining needle stubs. This insect leaves no

webbing.

Pine needle sheathminer Zelleria haimbachi Busck

Sometimes called the jack pine needle miner and pine needle

cutter, this insect may become a pest of jack and ponderosa pines

and supposedly will attack spruce and balsam fir also. It rarely

causes heavy defoliation and has not yet become important in the

Lake States.

Terminal needles hollowed out at their bases from summer

through spring indicate the presence of this pest. Injured needles

are usually near a male flower cluster (plate 53, A), Look for a

silken tube across the bases of several needles, a small hole in the

34
needle sheath (plate 8, Z)), and drooping or broken off needles

(plate 6, A) in the spring and summer. One larva may destroy up

to 14 needles in a cluster. Needles are immature at the time of attack, but they do not bend over and fall off until they mature.

Drooping needles resemble damage done by the pine chafer, needle

droop, and needle blight, but damage from the miner can be distinguished by the holes in the fascicles and silken tubes. Pupae and

cast pupal cases are found in the silken tubes in June and July.

A pine needlemîner Argyrotaenia tahulana Freeman

This species is a minor pest of jack and ponderosa pine. The

larva first mines a single needle from the tip to the base, then it ties

a bundle of needles together and lines the cavity with silk. It adds

new needles to the bundle and mines them as it develops. Look for

a needle bundle that somewhat resembles that of the pine tube moth

(plate 10, C). The latter, however, makes its bundle on eastern

white pine.

A pine needleminer Evagora resinosae Freeman

This insect attacks red pine but is probably unimportant as a

forest pest. Known in Canada just north of Minnesota, it probably

is present in Minnesota.

One or more needles mined from the base or center to the tip is

evidence of this insect. Look for a short, flimsy, silk tube constructed around the entrance hole on the flattened surface of the

needle and attached to an adjacent unmined needle. Frass is ejected

from the entrance hole and from one or two other holes located on

the surface of the needle.

Larch casebearer Coleophora laricella (Hbn.)

This insect is a serious defoliator of larch, second only to the

larch sawfly in North America. A native of Europe, it was discovered on the east coast in the 1880's and has since spread westward. Several severe outbreaks have caused extensive tree mortality in some parts of its range. It attacks native and exotic larches

of all ages.

Infested stands may have dead and dying trees with brownish

foliage, as if scorched by fire or late frost. Foliage discoloration

occurs in the spring when the needle tips are mined by the larvae.

These mined needles drop prematurely. Unless severely weakened,

the trees will refoliate the same year. Severe and repeated attacks,

however, kill branches and trees.

Look for small gray cases (l^ inch long), each comprised of

parts of a hollowed-out needle and silk. These cases (plate 10, A),

35
which are attached to the twigs during the summer, fall, and winter, are diagnostic for this species. The larva lives inside this case.

Arborvitae leafminer Argyresthia thuiella (Pack.)

Severe infestations of this insect sometimes occur on cedar but

they are unlikely to cause permanent injury in forest stands. It is

important on ornamental arborvitae because the abundant brownish needles are unsightly. Heavy infestations kill branches and

cause foliage to drop prematurely.

In the fall or winter look for partly developed mines in the foliage

near branch tips (plate 4, J9). Frass is present but confined to the

outer tips during this period. In spring and summer, the mining

is extended and the frass ejected.

A juniper needleminer Phalonia rutilana Hbn.

This species, originally introduced into the eastern United States

from Europe in the 1870's now occurs as far west as the Lake

States. It sometimes becomes abundant on common juniper, but it

seldom causes more than some needle browning. It has been economically important only on ornamentals.

Look for the damage that first consists of several mined needles,

but later includes needles hollowed out from the concave surface.

Frass ejected from the mines adheres to the silk strands of webbing

spun between the mined and adjacent needles (plate 9, A).

A hemlock needleminer Pulicalvaria abietisella (Packard)

This insect is the most commonly observed leaf miner of hemlock

in the Lake States, but it has not been an important pest. Its damage is characterized by six or more mined needles tied loosely together. In addition, look for an elongate silken tube constructed on

the underside of the branchlet at the ibases of the mined leaves.

Nearly mature larvae hollow out the lower surface, mostly because

they become too large to mine the flat hemlock needles.

SAPSUCKING INSECTS, MIDGES, AND MITES

The organisms in this category injure conifers by feeding on

their fluids. Many have specialized piercing and sucking mouthparts that withdraw plant fluids through the needles, shoots, or

stems when inserted into the host.

Damage by some aphids, spittlebugs, and mites resemble disease

injury and may be mistakenly regarded as disease-caused if the

insects are absent. The destructive stage of the organism is usual36
ly required for precise identification, but sometimes the presence

of feeding punctures, sooty mold, nondestructive stages of the pest

(e.g., eggs), fine webbing, etc., may suifice for identification or at

least for distinguishing the injury from that of a disease. Some

sapsucking insects produce characteristic galls or pitch exudations

that identify them.

Scales are usually identified directly from the scale insect itself.

The female scale remains attached to the host for a long time, even

after death.

Spittlebugs

Spittlebugs are unique insects whose nymphs cover themselves

with a frothy mass of bubbles composed of eliminated plant juices.

Both adults and nymphs feed on plant fluids, but only the nymphs

make spittlemasses. Some spittlebugs feed on just one host species

in both the nymphal and adult stages ; others require different host

species for different stages. Two spittlebugs belonging to the genus

Aphrophora are especially destructive in the Lake States.

Saratoga spittlebug Aphrophora saratogensis (Fitch)

The Saratoga spittlebug kills sapling pines. It prefers red and

jack pine, but sometimes attacks Scotch pine. These hosts are susceptible to injury when growing with abundant ground cover, particularly sweetfern (fig 10), which is important to spittlebug

'S^

i»--'

FIGURE 10.—Sweetfern plant.

F-B02131

37
population buildup. Most other plants (except grasses, lichens, and

sedges) support Saratoga spittlebug nymphs, too, but to a lesser

degree. Trees taller than 15 feet are seldom attacked, mainly because they shade out the ground cover.

Trees die from the top down in heavy infestations. Symptoms

include dead tops, flagged branches (plate 12, B), wavy and stunted

stems, and shortened stem and branch internodes. In general, injury commonly resembles injury from the pine spittlebug, Scleroderris canker, and drought. Look for reddish flecks and pitchy scars

(plate 33, B), which are associated with adult feeding wounds and

can be observed by scraping the bark off branches with a knife.

These are diagnostic for this spittlebug and separate it from all

other insect and noninsect injury.

Also, look for the nymphal stages feeding from mid-May to early

July in spittlemasses at the bases of low-growing plants nearby

(plate 22, C and D), which are essential for the insect's survival.

Young nymphs are red and black ; older ones are chestnut brown

and sometimes in aggregations of up to 50 in a spittlemass. The

adults have a white "arrow" covering the head and thorax (fig 11),

FIGURE 11.—Saratoga spittlebug adult.

F-516023

88
which easily separates them from related species. Adults are present on the trees from late June to early September. The teardropshaped eggs overwinter and can be easily found under the scales of

larger buds (fig 12).

F-489363

FIGURE 12.—Saratoga spittlebug eggs.

Pine spittlebug Aphrophora paralíela (Say)

The pine spittlebug feeds on conifers of all sizes, including

seedlings, but it most commonly attacks saplings and poles. It prefers eastern white, Scotch, and jack pine; but may attack several

other pines as well as spruces, larch, hemlock, and fir. It rarely

attacks red pine. Outbreaks are usually localized.

Trees may die from heavy infestations. The primary symptom

is branch nagging starting on the new grovrth and progressing to

the trunk (plate 12, B). Lower branches generally flag first. In general, injury to saplings of jack and Scotch pine resembles injury of

the Saratoga spittlebug. Look for reddish flecks and scars (plate

33, B) caused by adult feeding. Such flecks on the inner bark are

diagnostic for this spittlebug and can be observed by cutting and

peeling back the bark of branches. The nymphal stages feed from

mid-May to July in spittlemasses on the host tree (plate 22, A

and B). Trees appear to be covered with snow during severe infestations. Many needles become black from a sooty mold (plate 12, D)

that grows on the sugary spittle dripping from the spittlemass.

The young nymphs (plate 22, B) are orange and black; older ones

range from light brown to black. More than one nymph may occupy

39
a spittlemass. Adults resemble other species of Aphrophora, but

lack the "arrow" of A. saratogensis (fig. 11).

Signoret spittlebug Aphrophora signoreti (Fitch)

This is a rare insect that causes little damage. It feeds on pine

and larch saplings and has been collected from white spruce and

balsam fir. Nymphs feed on low-growing plants near the adult host

similar to the Saratoga spittlebug (plate 22, C and D). The young

nymphs resemble those of the Saratoga spittlebug; the last instar

nymph, however, has a brownish yellow to pink abdomen. The

adult, is similar to, but more robust and darker than, either the

Saratoga spittlebug (fig 11) or the pine spittlebug.

A pine spittlebug Clastoptera testacea (Fitch)

This species is seldom injurious. Pines are the preferred hosts.

Look for the nymphs feeding in small spittlemasses (plate 22, A)

in June. The adults are small and oval (similar to fig. 13).

FIGURE 13.—Juniper spittlebug.

(Photo courtesy of the Michigan Department of Agriculture.)

A juniper spittlebug Clastoptera juniperina (Ball)

This species, introduced from western North America, is seldom

injurious. It prefers junipers and arborvitae—especially ornamental varieties. Look for the nymphs feeding in small spittlemasses

(plate 22, A) on juniper or arborvitae in June and July. The adults

are small and oval (fig. 13).

40
Scales

Scale insects are so called because some secrete a scalelike wax

coating over their back and others resemble bark scales. Scales are

commonly grouped as soft, armored, or woolly, depending on the

nature of their covering. All injure their hosts by extracting plant

fluids and injecting toxic saliva into the tissues. Some scales cause

extensive mortality in forest stands; others are mainly pests of

ornamentals. Symptoms of scale injury are typical of other sucking

insects : the host becomes devitalized, branches flag, some trees die.

Surviving trees are stunted and distorted. A black, sooty mold

(plate 12, D) that grows on honeydew (an excretion given on only

by the soft scales) is helpful for identifying a soft scale infestation.

However, for positive identification the scale itself should be found

because this sooty mold is also associated with honeydew of aphids

and the spittle of spittlebugs.

Most scales are easy to identify because they differ in shape

and size and remain on the host for a year or more. The female

is usually used for identification. Scales are flattened, hemispherical, helmetlike, saclike, globular, elongate, or rounded. Some

are covered with a white or yellow wax that looks like powder or

a cottony mass. The latter ones resemble certain aphids v^h similar

structures. Do not confuse fruit such as juniper berries (plate

19, D) with scales.

Pine tortoise scale Tourneyella numismaticum (P. & McD.)

The pine tortoise scale is very destructive in forest stands of

jack and Scotch pines, particularly to sapling and pole-sized plantations. It also attacks Austrian and red pine, but less severely.

Sooty mold (plate 12, D) (growing on the honeydew that covers

the needles and twigs) is commonly associated with this insect and

is often the first symptom observed. Ants or bees may be found

feeding on the honeydew. Trees under attack first appear devitalized, then branches flag and lose their needles. Trees may die after

only 2 or 3 consecutive years of attack.

The adult female scale is diagnostic for this species. It looks like

a small (% to 14 inch), reddish-brown helmet or tortoise stuck to

the new or old twigs of its host (plate 19, A). It is usually clustered

together with other females and small, whitish, elongate males

(plate 19, B). In the summer, the bark and needles may be covered

with small reddish specks that resemble red pepper to the naked eye.

These^are crawlers, or the first nymphal stage of the scale, that

move around before settling down.

41
Pine needle scale Phenacaspis pinifoliae (Fitch)

The pine needle scale commonly destroys conifers of all sizes.

Eastern white and mugo pines are very susceptible; other pines,

spruces, fir, hemlock, and yew, are also attacked. Early symptoms

are yellowing and browning of infested needles, followed by early

needle fall. Heavy attacks kill twigs, branches, and trees. The

scales appear to the naked eye as small (i/g inch long) white necks

on the needles (plate 16, C), On closer examination the scale is

elongate, flattened, and white with a small orange or yellow cap at

one end (plate 16, D), A white, waxy secretion given off by the

scales makes the foliage look gray.

Black pineleaf scale Nuculaspis californica (Coleman)

This insect is widely distributed and sometimes causes extensive

outbreaks in western North American pine forests. In the Lake

States, it injures jack and mugo pines of all sizes. Unlike in the

West, infestations are generally localized, sometimes confined to

just a few trees. Infestations are commonly associated with environmental conditions harmful to the hosts, such as fumes, smog,

smoke, and dust. Viewed from a distance, infested trees resemble

those attacked by bark beetles (i.e., clusters of dead trees). Infested trees are most noticeable in the spring when the discoloration of injured needles becomes most pronounced and is not obscured by new foliage. Injured needles turn yellow and finally drop

off prematurely. Sparse, short needles characterize a persistent

infestation (plate 13, B).

Close examination reveals grayish-brown to black scales packed

tightly on the needles (plate 17, A). Each scale is less than %6

inch long and has a small '^nipple'' on its back (plate 17, B).

Juniper scale Diaspis carueli Targ.-Tozz.

This scale is a serious pest of ornamental varieties of juniper

and arborvitae. Injury appears as yellowing of needles, branch

flagging, and tree mortality. The scales, which are commonly in

dense clusters on the needles, twigs, and cones, appear as white

flecks to the naked eye. Close up, each scale is glistening white to

gray, flattened, nearly circular, and about ^/2o inch in diameter

(plate 18,2)).

Fletcher scale Lecanium fletcheri Ckll.

A common pest of yew, this scale also attacks arborvitae and

juniper. When abundant, it causes yellowing of foliage, premature

needle drop, and eventual death of branches or the entire tree.

Sooty mold (plate 12, D) growing on honeydew on the foliage is

42
associated with the scale. The scales feed in clusters on the stem

between the needles. The female scale is yellowish to reddish

brown, helmet shaped, and about i/s to i/e inch long (plate 18,

A and B). Many are slightly wrinkled.

Spruce bud scale Physokermes piceae (Sehr.)

This scale, when abundant, kills twigs and branches of spruces.

It thrives on weak trees and further reduces their vitality. Sooty

mold, (plate 12, D) growing on honeydew exuded from the scales,

is commonly present. The scales feed at the bases of branchlets.

They are globular, reddish brown with irregular flecks of yellow

(plate 19, C), and easily mistaken for abnormal buds.

Hemlock scale Aspidiotus abietis Coinst.

This scale injures hemlock but is seldom serious. At worst it

causes some needle discoloration and premature needle drop. Sooty

mold (plate 12, D) grows on the honeydew given off by this insect.

The scales feed mostly on the lower surface of hemlock foliage.

Fully developed scales are dark gray to black with light edges.

Woolly pine scale Pseudophilippia quaintancii Ckll.

This scale, rare in the Lake States, attacks young pine saplings.

Large clusters of scales on the new needles cause the shoot to flag.

This scale has been found on red and mugo pine and probably

attacks other pines. Sooty mold (plate 12, D) commonly grows on

the honeydew it gives off. The scales are woolly (plate 20, B) and

found in large clusters on the shoots and needle bases.

A balsam fir scale Pulvinaria (?) sp.

Little is known about this scale, found on balsam fir in the Lake

States. Like most scales, it is potentially destructive. This woolly

insect clusters on the underside of the needles (plate 20, C).

Taxus mealybugs Pseudococcus spp.

Mealybugs are closely related to scales ; several species are common pests of yew in the Lake States. The heaviest infestations

occur on hosts having compact, dense foliage. Greenhouse trees are

more susceptible than forest or ornamental trees. Feeding discolors the needles, and if it is intensive and prolonged, kills the

trees. Most species secrete honeydew, which is covered with sooty

mold (plate 12, D).

Unlike scales, these insects retain their appendages and can

move about slowly. The bodies are oval, about 14 inch long, and

43
generally covered with a powdery wax. Also, wax filaments project

from their sides forming a fringe around them. Some species have

long, waxy, taillike projections. Superficially, they look like woolly

scales and woolly aphids (plates 18, C, and 20, A through D).

Plant Lice

Plant lice or aphids are small sucking insects (plate 21, D)

usually grouped in clusters on the needles, shoots, or stems of the

host. They are serious forest pests, able to kill trees of all sizes.

Many are naked (plate 21, D) ; others are covered with a woolly

wax (plate 18, C) as are some scale insects. Some produce honeydew, which drips onto surrounding foliage and becomes covered

with a black sooty mold (plate 12, D). This sooty mold is also associated with the soft scales and spittlebugs. Ants and bees feed on

the honeydew and are commonly found with or near the aphids.

Some aphids move to an alternate host plant after one or more

generations. Other aphids produce galls on spruce and some of

these have alternating generations on other conifers. These gall

aphids are discussed in the next section.

Pine bark aphid Pineus strobi (Htg.)

This aphid was probably imported into North America from

Europe. It is a serious pest of nursery, ornamental, and planted

eastern white pine. Infestations are heaviest on large pines,

especially in well shaded areas. Other pines have been recorded as

hosts of this insect, but these infestations probably were of the

closely related P. coloradensis.

The pine bark aphid feeds on the bark of the stem and branches.

Heavily infested trees, especially if young, become stunted, bushy,

or die. Look for the aphids, which appear as scattered patches of

white necks, on the bark of the stem (plate 43, A) and the lower

side of limbs (plate 21, A). A white waxy secretion hides the body

of the small dark aphid.

A pine needle aphid Pineus coloradensis (Gillette)

This aphid closely resembles the pine bark aphid and may be a

serious pest of pines. It prefers red pine but can survive and

develop on eastern white, jack, and Scotch pine.

This aphid feeds on the new needles of its hosts, causing the

trees to become stunted and flagged. New eastern white pine

needles collapse from feeding. Look for the aphids, which appear

as white patches on the new needles (similar to plate 21, A). Sometimes during August a sooty mold (plate 12, D) grows on the waxy

secretion of the aphids causing the wax to appear almost black.

44
Spotted pine aphid Eulachnus agilis (Kaltenbach)

This insect is not yet important in the Lake States, but it has

injured Scotch and Austrian pines in adjacent States. The aphids

feed in colonies on both old and new needles causing them to

blotch, turn yellow and brown, and drop prematurely. The aphids

(similar to plate 21, D) are green with red eyes and a spotted body.

White pine aphid Cinara strohi (Fitch)

This insect is present throughout the Lake States and is commonly abundant in Michigan on eastern white and Scotch pine. It

causes flagging and mortality, especially of young trees. Abundant

honeydew covered with sooty mold (plate 12, D) is associated with

these aphids. The aphids are dark brown to black with white

markings. They are clustered on the shoots and branches (plate

21, D). Look for the aphid's black shiny eggs (plate 21, B) laid in

rows on the needles.

A pine aphid Cinara pini (L.)

This large and conspicuous aphid occasionally injures Scotch

pine^—especially young trees in Michigan. The aphids occur in

colonies (plate 21, D) and are reddish brown and flecked with dark

specks.

Balsam twig aphid Mindarus abietinus Koch

This aphid sometimes becomes abundant on balsam flr. It has

also been reported on Scotch pine and blue spruce. When the

aphids are abundant, the shoots flag and die. Young needles become curled and expose their undersides. Honeydew, covered with

sooty mold (plate 12, D), is commonly on the foliage near the

attack.

Look for large females, known as stem mothers, that are covered

with a white woolly wax in the spring (as plate 18, C). The rest of

the summer the aphids are naked, pale green, and located in clusters on the needles and shoots (plate 21, D).

Aborvitae aphid Cinara tujafilina Del G.

This insect is very destructive on arborvitae. Branches of heavily attacked trees flag and die. Look for the hairy, amber-brown

aphids, which are about Vs i^ch long and have their upper surface

covered with a white, powdery fllm making them inconspicuous.

They feed in large colonies (plate 21, D) on the bark of the shoots.

Honeydew is secreted copiously and sooty mold (plate 12, D) is

usually present.

45
Red cedar aphid Cinara sahinae (Gill. & Palm.)

This aphid occasionally becomes abundant on junipers, and kills

mostly branches. Few trees are killed directly by the aphids, but

they are often weakened enough that the cedar bark beetle (p. 71)

attacks and kills them.

The aphids feed in colonies (plate 21, D) on the new shoots. They

are about Vs inch long, brown, and not easily seen on the tree's

reddish bark. Their presence is more easily determined by the

glossy honeydew and sooty mold (plate 12, D) that grows on it.

The aphids leave the tree in summer, usually before the damage is

apparent.

Pine root aphids Prociphilus spp.

Aphids of the genus Prociphilus are occasionally found on roots

of pine seedlings and young saplings up to 5 feet tall. Infested

trees may be stunted (plate 31, C) and have yellowing foliage. Look

for the light-colored aphids in clusters (plate 21, D) feeding on

large roots a few inches below the root collar.

Gall Aphids

These aphids (or adelgids) all produce conspicuous, enlarged

growths or galls on the shoots of various spruce species. Some

require one or more alternating generations on an alternate host

such as pine, larch, or fir. They do not produce galls on the alternate hosts, but appear as colonies of plant lice (plate 21, D) on the

needles or shoots.

The aphid galls on spruce seldom become abundant enough to

cause serious damage in forest stands, but they are often unsightly on ornamentals. Galls differ in shape, size, and location on

the host depending on the species of aphid. Some galls are loosely

developed, others are conelike or resemble small pineapples. They

range from 1/3 inch to several inches long and most are green or

purple while developing but become reddish brown later after they

are vacated. Inside the galls are numerous chambers in which the

nymphs develop. Many injured shoots become deformed or die. The

spruce gall midge (p. 51) causes a gall similar to aphid galls.

Eastern spruce gall aphid Adelges abietis (L.)

Galls of this insect are commonly observed on white, Norway,

and black spruce saplings. All stages occur on spruce and no alternate host is required. Forest stands are not significantly injured

by attack, mainly because the buds on the injured shoots are not

46
damaged. The galls are unsightly and disfigure the shoots on ornamentals. Many hundreds of galls may occur on one tree, and a tree

that is attacked is often repeatedly and heavily galled. Some trees

are conspicuously immune to attack even when grov^ing adjacent to

injured ones.

Look for this gall, v^hich is 1/2 to 1 inch long, at the base of the

new shoot (plate 23, A). When fresh, the gall is green with a reddish line around the mouth of each of the chambers. The needles

comprising the gall are shortened to about half normal length.

The winged female adults are sometimes seen as whitish necks

on the needles (plate 17, C). The females die while egg laying and

remain attached to the needles (plate 17, D). The ^'spring nymphs''

are typically aphidlike, but are covered with a white, woolly wax

(similar to plate 18, C), as are the eggs (plate 20, A).

Cooley spruce gall aphid Adelges cooleyi (Gill.)

The gall of this insect is common and important on blue spruce

planted as an ornamental. Very young spruces may be severely

deformed or weakened during heavy attacks because the buds die

on the gall-infested shoots. This insect may have alternating generations on Douglas-fir, but it is able to complete its life cycles on

either host.

On spruce, look for the gall, which is 1 to 3 inches long, loosely

structured, and always occupies the end of the shoot (plate 23, B),

When fresh, the gall is light green to dark purple and the needles

comprising it are nearly as long as normal ones.

On Douglas-fir the insects act like typical plant lice and feed in

clusters at the bases of the needles. The insects are dark green to

brown and exude large amounts of dense, woolly wax (plate 18, C).

Their feeding causes yellow spots on the needles. Later, entire

needles may become yellow and drop prematurely. Attacks may kill

nursery seedlings and very young trees. Infestations on large trees

are commonly confined to the lower branches.

Woolly larch aphid Adelges strobilobius Kalt.

This insect, introduced from Europe, is a minor pest on black

spruce and occasionally becomes a pest on eastern larch—^the alternate host.

On black spruce look for the rounded gall, up to an inch long

(plate 23, D), at the tip of the new shoot. The needles of the gall

are shortened. When fresh, the gall is pink to green.

On larch in the fall, the small, dark insects appear in thick clusters at the bases of needle clusters (plate 21, C) or on the underside

of shoots. Spring aphids (fig. 5) and their egg clusters are on the

47
needles and are mostly covered with a white, woolly wax (plate

20, D).

Pine leaf chermid Pineus pinifoliae (Fitch)

This insect is not serious on black spruce in forest stands, but on

ornamental Norway spruce the galls sometimes become numerous.

Eastern white pine is the usual alternate host ; red and other pines

possibly also serve as alternate hosts. It often injures the pines.

On spruce, look for a compact gall resembling a true cone on the

tip of the new growth (similar to plate 24, B). It varies from % to

1% inches long, and when fresh, is purple or green. The gall deforms the tree because the buds are killed and the shoot dies.

On eastern white pine, the aphids settle on the new needles or

shoots in early summer and become covered with a woolly wax

(plate 20, B). Twig tips flag where feeding is excessive.

Red spruce aphid Pineus floccus (Patch)

This aphid produces galls on black spruce but has never been an

important pest. It requires eastern white pine as the alternate host.

On spruce, look for the conelike, loosely structured gall, that comprises the entire new shoot (plate 23, C). The gall is green and may

have a dark-purple tinge near the needle bases giving it a purple

cast at a distance. The length ranges from % to li/^ inches and the

needles of the gall are nearly normal in length.

On pine, the aphids are typical plant lice covered with a flocculent, white, woolly wax (plate 24, B), They settle and feed on the

old shoots and needles.

Spruce gall aphid Pineus similis (Gillette)

Seldom an important pest, this insect produces galls on white,

black, Norway, and blue spruce. An alternate host is not known.

The gall comprises the entire new growth but it is loosely structured and from % to 1% inches long (plate 24, A). Superñcially, it

resembles the gall formed by the spruce gall midge (p. 51), but if

cut open, can be distinguished by the young aphids instead of the

legless fly maggots (plate 26, ß).

Unknown spruce gall aphids Adelges spp. et al.

Several unknown aphids produce galls on spruce. None, however,

are important pests. The various galls are shown in plates 24 and

25.

48
Thrips

These minute insects are common in the flowers of many species

of plants, but are seldom noticed because of their small size. They

are rarely injurious in forests but occasionally become a pest to

ornamentals, nursery seedlings, and Christmas, trees. Only one

species has been important in the Lake States.

Pine thrips Gnophothrips sp.

Pine thrips of one or more species attack Scotch and Austrian

pines. They are sometimes especially abundant in Christmas tree

plantings and nurseries. Their feeding damage appears as small

brown patches up to l^ inch long on the new needles (plate 14, D).

Heavy attacks stunt and distort the needles and shoots (plate

14, C), and cause needle yellowing and premature needle fall. On

the needles, search for the adult thrips, a black, winged insect

about 1/16 inch long (plate 14, D). Immature thrips are similar in

shape but lack wings and are orange yellow.

Midges

Midges are small mosquitolike flies that are injurious in the

larva or maggot stage. Some cause conspicuous galls on the needles

or twigs of conifers. Others live in shallow pits in the twigs or at

the needle bases, and are commonly covered with a pitch exúdate.

A few bore into and destroy needles.

A pine pitch midge Cecidomyia reeksi Vockeroth

This is the most prevalent pitch-forming midge in the Lake

States. It attacks jack pine of all sizes, but prefers open-grown

saplings, especially on poor sites. Most injury occurs to young

reproduction, which can be killed outright. On older trees, terminals and branch tips may be killed. Injured trees become stunted

and deformed.

Look for flagged shoot tips occurring with one or more resin

masses at or near the base of the flagged portion of the shoot (plate

39, A and B). These semifluid exudates, which may be up to i/^

inch in diameter, contain a few to many yellow-orange midge

larvae or pupae, or cast skins, depending on the time of examination.

A pine pitch midge Cecidoniyia banksianae Vockeroth

A minor pest, this insect is occasionally observed on jack pine in

the Lake States. It feeds close to the bud in a cavity filled with

49
resin. Usually only one larva occurs in each cavity, but several may

be present. Infested shoots die in the spring. Look for dead buds or

short, discolored shoots that bend dov^nv^ard at the point of injury

(similar to plate 37, ß).

Gouty pitch midge Cecidomyia piniinopis (O.S.)

The gouty pitch midge severely deforms and sometimes kills its

host. It has been reported on 4- to 16-foot jack pine in Michigan.

Small trees are generally not injured severely.

Dead needles, dead or dying shoot tips, and twisted terminals

are evidence of this insect. In the early stages of injury, dead

needles appear in tufts on the new growth (plate 13, C). Heavily

infested shoots flag, die, and drop off.

Damage superficially resembles that of other insects but can be

distinguished simply by examining the attack sites of the midges.

Look between the needles of the new growth for slight swellings

on the bark. Each swelling contains a small pit or pocket (Vs inch

diameter) enclosing a single orange-red larva emersed in resin

(plate 39, C and D), The resin commonly exudes over the surface

of the twig. The needles surrounding the pits are the first to die.

Balsam gall midge Dasineura balsamicola (Lint.)

The balsam gall midge is rarely important except to Christmas

tree balsam firs. The injured needles of the new growth drop off

prematurely after cutting. Look for the characteristic gall (plate

26, C), a globular swelling near the base of the new needles. Each

gall contains a small yellow larva in the summer.

Red pine needle midge Thecodiplosis piniresinosae Kearby

This insect causes needle injury commonly called *'fall browning.'' Red pine is its only known host. It attacks trees of all sizes

but prefers open-grown saplings, particularly those of low vigor.

Growth loss and shoot mortality occur in outbreaks lasting 3 or 4

years.

First evidence of this insect is usually a swelling (plate 26, D)

of the current year's needle bases beneath the fascicles where one

or more orange larva feeds. Infested needles, which are about 40

percent shorter than normal, turn yellow and then brown in October about the time the larvae drop to the ground. Look for the

galled needle bases and exit holes in the fascicles (plate 26, D) of

the short, reddened needles, which are diagnostic characteristics

for this insect. In heavy infestations more than 75 percent of the

current year's needles may die and fall during the winter. When

heavy attacks occur, the buds fail to grow the following year. This

50
produces crooks and forks in the terminals and laterals. This insect

is often associated with the needle blight midge (p. 51) and needle

droop (p. 86)—two other maladies of red pine.

A "needle blight'' midge Unknown species

This unnamed midge causes extensive needle injury to red pine

saplings and may destroy up to half of the current year's needles.

New needles become sharply bent or hooked in the fascicle region

(plate 6, A). Some drop to the ground while still green, others turn

yellow and then drop in August and September. These needles

accumulate on the foliage below, increasing discoloration of the

tree. Look for a constricted necrotic zone inside the fascicle attended by yellowish midge maggots. Needle drooping caused by

this insect superficially resembles injury by the pine chafer

(p. 24). Injury by this midge, however, occurs later in the season.

Juniper tip midge Oligotrophus betheli Felt

This midge is known to occur in Michigan and occasionally becomes a serious pest of ornamental junipers, particularly in nurseries. The growing shoot tips are attacked (plate 13, A) but seldom

are more than the buds injured. When many tips are infested, the

tree becomes dense and bushy. Look for a small, light-yellow maggot in each infested shoot tip during most of the warm season.

Spruce gall midge Mayétiola piceae (Felt)

This midge produces a gall on the shoots of white spruce, sometimes causing sufficient shoot injury to require attention. It attacks

trees of all sizes.

The galled part of the new shoot (plate 26, A) resembles certain

aphid galls, especially those of the spruce gall aphid (p. 48). The

gall is loosely structured and about twice the thickness of the normal shoot. It may cause the shoot to twist. The larval cells appear

as hemispherical swellings between the needles (plate 26, A and

B), The galled shoot may die and drop its needles during the season of attack or it may survive to produce a new shoot the next

year. When the latter occurs, the new growth either dies or grows

crooked into a drooping ''pigtail.''

Look for the legless maggots present in the swollen areas of the

gall during the summer (plate 26, B), If there is a small hole in

each swelling, the insects have emerged.

Mites

Mites are arthropods more closely related to spiders than insects. The injury they cause, however, is similar to that caused by

51
sapsucking insects. Both the adult and immature stages feed on

plant fluids. When abundant, mites weaken and kill trees of all

sizes. Forest nursery seedlings and ornamentals are commonly

attacked ; forest trees less so.

Because some mites are very small (1/50 inch or less) they go

undetected, and the injury they cause is sometimes diagnosed as

caused by drought or nutrient deñciency. A 10- or 15-power hand

lens is usually required to see them on conifer foliage. A simple

method of checking for exposed mites is to shake or strike an

injured branch over a piece of white paper. The mites will appear

as tiny, moving, and yellow, green, or red specks on the paper.

Spruce spider mite Oligonychus ununguis (Jacobi)

This mite is the most important mite of conifers in the Lake

States. It is usually a serious problem on planted conifers—

especially in stands where insecticides have been used repeatedly to

control defoliating insects and thereby also have killed the predators of the mites. It prefers white and blue spruce, but will attack

black spruce, larch, balsam fir, arborvitae, hemlock, juniper, and

some species of pine.

The mite causes mottled, yellowish discolorations on the needles

(plate 9, D). Severely infested foliage is dingy yellow or brownish;

many of the needles dry up or drop off. Injury starts on the lower

branches and progresses upward. Look for fine webbing that

usually coats the needles of injured branches (plate 9, D). Dust

particles, pollen, shed needles, etc., in the webbing add to the unhealthy appearance of the trees. Mite damage is severest in warm,

dry weather—heavy rains tend to wash mites off the trees.

The adult is about 1/50 inch long; immature stages are smaller.

The body is bluish to almost black with yellowish to pink extremities.

Twospotted spider mite Tetranychus urticae Koch

This mite, sometimes simply called a red spider, can be very

destructive to many species of conifers. The symptoms of attack

are similar to those of other mites. The foliage fades, turns brown,

and then falls prematurely. Look for signs of the mites such as

webbing on the foliage which contains considerable debris (similar

to plate 9, Z)). Using a hand lens, examine the foliage for the mites.

This species is 1/50 inch long, spiderlike, and usually greenish but

sometimes yellowish or reddish. There are two large black spots on

its back.

52
A red pine eriophyid mite Setoptus sp.

This mite has become an important pest of red pine in recent

years, especially in plantations in Michigan. The same or a closely

related species attacks eastern white pine. Its injury is sometimes

wrongly ascribed to drought or nutrient deficiency because there is

no telltale webbing and the mites are difficult to detect with the

naked eye.

Injured foliage is yellowish at a distance. Close up, the needles

have a blotchy, pale yellow, stippled appearance. The tips of the

injured needles are twisted or hooked (plate 14, A) and may be

brownish if the injury has progressed sufficiently. With a hand

lens, look for the mites between the needles or inside the needle

sheath. The mites are elongate and wormlike (plate 15, B), only

1/125 inch long, and vary from creamy white to orange yellow.

Tipdwarf mite Calepiterimerus thujae (Garman)

This mite is a pest of junipers and arborvitae, mainly on ornamentals. It occurs in the growing tips, which become constricted

and crooked. Affected trees are slightly discolored to rusty brown

depending on the severity of attack. Using a hand lens, look for

small, wormlike, grayish mites (similar to plate 14, B) in crevices

or on the foliage. The mites are more triangular than elongate

when young. They are seldom seen on the foliage surface unless

the weather is humid and the temperature is 60°F or lower.

SHOOT, STEM, AND ROOT INSECTS

Insects in this category gnaw on the surface of or inside shoots,

stems, and roots of conifers, and cause malformations, degrade,

and mortality. Many are '^primary" insects that injure healthy

trees, but also included here are the "secondary" insects—ones that

successfully attack only trees that are weakened, dying, or dead

from other causes. Wood borers and bark beetles are mostly secondary insects, although these groups contain a few species that

can attack and survive in apparently healthy trees.

Shoot and Bud Moths

The larvae of this group of moths bore into buds and shoot tips

of pines. Their feeding does not kill the tree but does cause malformation of the main stem and branches. Some species are extremely

destructive.

53
European pine shoot moth Rhyacionia buoliana (Schiff.)

This is one of the most destructive shoot-boring moths in the

Lake States. Introduced from Europe, it has spread from the East

into Michigan and Wisconsin. It prefers red pine but readily attacks Scotch, Austrian, and ponderosa pine; it rarely injures jack

and eastern white pine. Seedlings and young planted saplings and

ornamentals are especially susceptible to attack, but trees more

than 15 feet tall are rarely attacked.

First evidence of attack is a fev^ dead needles on the terminal or

lateral branches near the buds in late summer. Later the larva

injures the bud (plate 29, A) and produces a small, pitchy blister

(plate 38, D) composed of pitch-infiltrated v^ebbing at the base of

the larger buds. Look for this blister that covers a small, brown

larvae feeding on the bud or new growth tissues (plate 29, A). In

the spring, elongating shoots bend over and die, or grow crooked

(plate 30, A and B), developing into a characteristic deformity

called a *'post horn'' (plate 36, A). Bushy tips (plate 36, D) develop when all buds in a cluster are killed. Crooks and forks

(plates 36, B and C, and 42, C) develop when one or more lateral

shoots gain dominance. Bushy or spike-top trees (plate 32, D) are

typical of advanced infestations. Many trees are irregularly

shaped, have especially long lateral branches, and some nodes

depleted of branches (plate 36, C).

Other pine shoot moths Rhyacionia spp.

Three species of lesser importance than the European pine shoot

moth attack pines in the Lake States : R. adana Heinrich, R. busckana Heinrich, and R. sonia Miller. All three species cause similar

damage. Also the larvae are similar, so adults must be reared for

positive identification.

Only R, adana has caused noticeable damage in the Lake States,

especially on very young trees. Young larvae first mine old needles

near the bud, then later mine out the young developing shoot

shortly after new needle growth has begun. Several larvae may

bore into one shoot and kill it before it elongates. Look for a small

hole (plate 29, B) at the base of the injured shoot. Typically, new

growth becomes stunted and it flags in midsummer. Heavily attacked trees become stunted and distorted like those attacked by

the European pine shoot moth.

Eastern pineshoot borer Eucosma glorióla Heinrieh

Also known locally as the American pine shoot borer, the jack

pine shoot borer, and the white pine tip moth, this insect has long

been a moderately injurious pest of pine in the Lake States. It has

54
been reared on eastern white, jack, red, Scotch, mugo, and Austrian

pine and white spruce and Douglas-fir. The insect prefers new

shoots of saplings but it will attack shoots of trees up to 30 years

old. Many Christmas tree plantings are heavily attacked.

The larva of this insect attacks the new growth on laterals and

terminals of its host in May and June before the shoot has fully

elongated. One or occasionally several larvae hollow out most of

the pith of the new shoot (plate 33, D) and emerge through an

oblong or circular exit hole (plate 34, C), often before the damage

is noticeable. Look for this exit hole—a sure sign of this species.

Injured shoots turn yellowish and then reddish after mid-June

(as plate 33, C). Many terminals and some laterals fall over (plate

35, A) or break off 1 to 3 inches above the old grovd;h leaving a

short flat stub. Some shoots, especially on red pine and Douglas-fir,

may wilt and droop (similar to plate 37, B) before yellowing. Small

attacked shoots, which may die before mid-June, are usually ones

in which the insects have died prematurely. Such shoots contain

only a partially excavated pith gallery and are heavily pitch soaked.

Crooks and forks develop when the terminal is killed. Old injury

appears as deformed or crooked trees.

Pine candle moth Exoteleia nepheos Freeman

Discovered only a few years ago, this pest has become destructive to young Scotch pine plantings, especially in Michigan. It also

attacks sapling Austrian, red, and mugo pine but to a lesser degree.

The damage externally resembled that of the Rhyacionia. Look

for dead buds or short, wilted, new-growth shoots (plate 30, C)

caused by larvae feeding in the old shoot tissues. Most injured

shoots die and give branches a tufted appearance. When leaders

are attacked, forks develop in the main stem. The larvae also attack

and feed on the male flowers (plate 53, A).

This insect's damage can be distinguished from that of Rhyacionia buoliana by the lack of a pitch blister (plate 38, D) at the

attack site. Exoteleia spins a loose web near the point of attack

(plate 29, C) on the buds or male flowers, but is evident only during the early feeding stages.

A bud borer Petrova pallipennis Mcd.

This insect has never been economically important except in

localized stands on jack pine. The larva destroys one or more buds

on its host. Damage is readily evident in the spring when the

hollowed-out buds fail to elongate like normal ones. Look for a

small, round hole, which is closed with webbing if the larva is

inside, near the base of the bud (plate 29, C). Branches developing

from surviving buds become crooked or forked.

55
Pitch-Mass and Blister Makers

This is a heterogeneous group of boring insects (exclusive of

certain bark beetles, midges, and shoot moths) that produce conspicuous pitch masses or pitch blisters on the trunk, branches, or

shoots of living conifers. These masses consist of coagulated resin,

and they are either solid accumulations or blisterlike structures

located at the attack site. All these insects are injurious in the

larval stages.

Zimmerman pine moth Dioryctria zimmermani (Grote)

The Zimmerman pine moth severely damages saplings of several

native and introduced pines and occasionally injures pole-sized

pines. It prefers Scotch pine but v^ill attack red, jack, eastern

white, Austrian, mugo, and other pines. This insect bores inside

the base of the terminal shoot, lateral shoots, or any branches. On

jack pine, it commonly bores into the globose galls of the eastern

gall rust (plate 28, A). Damage may result in a forked branch or

death of the shoot, depending on location of attack.

Signs of attack on the terminal or upper shoots are accumulations of coarse "sav^dust'' in loose v^ebbing at the bases of branches

(plates 35, B; 40, C; and 42, D) accompanied by pitch. Branches

hang dov^n and flag (plate 35, B) or break off at the point of attack. This damage resembles that of the eastern pineshoot borer

(plate 35, A) and snow damage (plate 35, C) but differs by having

the characteristic pitch. Lateral shoot tips that are attacked flag

(as plate 35, C) and have a small pitch tube (plate 40, D).

A large (2 to 3 inches), solid, pitch mass (plate 41, A) or cluster

of masses at a node characterize an attack on the bole. The pitch

mass is whitish, irregular, and located between or below branches

or at wounds. It resembles the pitch masses of the pitch mass borer

(plate 41, B) and pitch mass beetle (plate 41, C), but it is usually

smaller than the former and more irregular than the latter. Stem

mining beneath the pitch mass may kill adjacent branches and part

or all of the tree above the attack site. The tree may break at this

location if the girdling weakens it suflSciently.

The bole of surviving trees may be forked, crooked, or constricted (plate 42, A). Heavily injured trees have a burllike growth

above the attack location (plate 42, A).

Look for the larva than can be found under the pitch mass or in

the pith of a shoot (plate 33, D), It is easily distinguished from

most other stem and shoot insects. The body ranges from pink to

gray to yellow and has rows of small dark spots. Pupae or cast

pupal cases in the shoots or stem are also diagnostic for this species.

56
Pitch mass borer Vespamima pini (Kellicott)

The pitch mass borer injures primarily eastern white pine but

it also attacks Scotch, Austrian, and red pine, and spruces. It prefers pole-sized trees, particularly those that have been pruned or

wounded. Trees are killed only when there are abundant and repeated attacks at the same locality. Defects are formed under the

bark and in the sapwood as a result of the burrowing larvae. Pupation occurs in the pitch mass.

A very large (3 to 4 inch), solid, pitch mass at the attack site is

characteristic. The attack site is on the bole, commonly at a pruning scar (plate 41, B) or wound. The pitch mass is similar to, but

often larger than, that of the Zimmerman pine moth (plate 41, A)

and much more irregular than that of the pitch mass beetle (plate

41, C).

Look for the larva that is present beneath the pitch mass for 2

or more years. It is distinguishable from other pitch mass borers

by having legs, and a pinkish-white body lacking dark spots.

Pitch mass beetle Chrysobothris orono Frost

This wood borer attacks nonvigorous red and jack pine saplings

but it has never been economically important. It destroys a small

amount of bark and cambium and excavates a short (2 inches),

shallow, L-shaped gallery in the sapwood, which would of course

show up as a defect in lumber.

The solid pitch mass (plate 41, C), up to 2 inches long, is similar

to the pitch mass of the Zimmerman pine moth and pitch mass

borer, but more oval or rounded and often pinkish. It is located on

either the node or internode of the main stem and usually on the

south-to-southwest side of the tree.

Look for the white legless larva (plate 41, Z)) that lives singly

under the pitch mass the first year and in the wood gallery the

second year. It is a typical ñatheaded borer, easily distinguishable

from the other pitch mass makers that have legs.

Northern pitch twig moth Petrova alhicapitana (Busck)

This insect, also called the pitch nodule maker or pitch blister

moth, is the commonest of the pitch mass and blister-making

insects in the Lake States. It occasionally injures the branches of

sapling jack and Scotch pines, preferring trees grown in open

stands.

Look for a hollow, thin-walled, brownish pitch ^'blister" (1 to

11/2 inches in diameter) located at the crotch of two or more twigs

(plate 38, A and B). This is the second year ''blister" and the one

most commonly observed in the field. The pitch blister made the

57
first year is smaller (less than V2 inch) and located on the new

shoot near the bud. The first and second year blisters may be on

the same branch. The first-year blister resembles early blisters

formed by the shortleaf pitch blister moth and is difficult to

distinguish from it. However, the second-year blister differs

greatly from the fully formed blister made by the shortleaf pitch

blister moth.

Tips of shoots above first-year blisters sometimes flag. Tips of

branches above the second-year attack site usually flag and break

off due to girdling of the bark by the small reddish larva (plate

38, B). This injury results in a forked branch or forked tree if the

terminal is killed. A branch not completely girdled grows crooked

and may break off—even several years later.

A pitch blister moth Petrova houseri Miller

Normally this insect attacks shortleaf pine south of the Lake

States, but the moth has been reared from jack pine in the Lake

States. It attacks current-year shoots, but the signiflcant damage

appears the year following. Look for the brownish pitch blister

(plate 38, C), formed the first summer and enlarged the following

spring. It differs from that of the northern pitch twig moth by

being much heavier walled, smaller (I/2 to % inch diameter),

commonly packed with debris, and located between the nodes

instead of at a branch crotch.

The larva tunnels for an inch or more in the bark and pith.

Girdling of the bark under the pitch blister causes the shoot to

flag.

Weevils

The weevils or snout beetles are readily distinguished from

other adult beetles by the head, which is more or less prolonged

into a beak (figs. 14, 15). The larvae are legless white grubs,

typically curved when at rest (fig. 16).

Some weevils are among the most destructive pests in the Lake

States. All the larvae are bark, wood, or root feeders; some live

only in dead wood or stumps. The adult weevils, however, all feed

on bark or foliage and thus some destroy conifer reproduction.

Some adults feed at night or on cloudy days and therefore are not

readily seen.

Two major groups of weevils, the Pissodes and Hylobius genera,

are especially important. The adults of one group are easily distinguished from the other (figs. 14, 15), but separation of those

within each group usually requires taxonomic skill. A few species

are morphologically inseparable and require other means of

58
FIGURE 14.—Pissodes weevil adult. (Photo courtesy of Michigan

State University, negative number 4907.)

identification. The grubs or larvae of all weevils are similar and

difficult to distinguish. The larval damage of most species differs,

however, and the species can usually be identified from it. Adult

Pissodes weevils make pin holes in the bark (similar to plate

34, B) and excavate the tissues beneath it; Hylobitis weevils

destroy bark in ragged patches (plate 34, D).

The other groups of weevils that attack conifers are separable

from Pissodes and Hylohius weevils as adults and by their injuries.

White pine weevil Pissodes strobi (Peck)

This weevil is the most destructive species of the genus in the

Lake States. It prefers eastern white pine but attacks other pines

and spruces. It breeds in and destroys the terminal growth

(leader), which causes forking and crooking of the tree. Opengrown trees from 2 to 20 feet tall are preferred.

59
Look for larval injury, which is diagnostic for this species. The

new growth either barely elongates (plate 32, ß) or elongates but

curls into a "shepherd's crook" and dies (plate 32, A through C).

Larval galleries occur in the new or previous year's growth starting at the top and meandering down into one or more stem internodes. When feeding occurs below a node, branches at that node

die too (plate 32, B). The larvae feed collectively down the stem

in the inner bark. They pupate in niches (plate 33, A) under chip

cocoons in the woody tissues in the lower end of the feeding area.

Adults prefer feeding on the previous year's terminal in the

spring, and on laterals in summer and fall. Feeding damage appears as small punctures in the bark covered with exuding or

hardened pitch globules (plate 40, A). The location of adult and

larval feeding damage distinguishes this insect on jack pine from

the closely related lodgepole terminal weevil. The adult is difficult

to distinguish from other Pissodes weevils (fig. 14).

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FIGURE 15.—Hylobius weevil adult.

Lodgepole terminal weevil Pissodes terminalis Hopping

This insect commonly attacks lodgepole pine. It also attacks

jack pine in the forests of Saskatchewan and probably occurs in

jack pine stands in northern Minnesota. It breeds in and destroys

the new terminal, which causes forking and crooking of the tree.

Open-grown trees 4 to 20 feet tall are preferred.

Look for symptoms of larval attack, which are diagnostic for

this species. Part or all of the new leader turns red, then brown,

and may break off during the summer. Tip curl (shepherd's

crook), similar to that of the white pine weevil (plate 32, A),

60
F-488106

FIGURE 16.—Weevil larva.

occurs on less than 40 percent of the injured trees. Larval galleries

begin anywhere along the leader and extend upward in the inner

bark. This upward rather than downward boring distinguishes the

damage from that of the white pine weevil. The larva feeds singly

and pupates in chip cocoons in the woody tissues of the leader

(plate 33, A).

Adults confine their feeding to the new growth. The feeding

injury resembles that of the white pine weevil—small punctures

exuding pitch (plate 40, A). The adult is difficult to distinguish

from other Pissodes weevils (fig. 14).

Northern pine weevil Pissodes approximatus Hopk.

This weevil attacks pines and spruces of all species and ages in

the Lake States. The Larvae develop in logs, stumps, and decadent

standing trees weakened or killed by drought, insects, diseases, or

other agents. The adults feed on the bark of young trees 0.5 to

10 feet tall. On trees less than 2 feet tall, adults feed only on the

main stem; on larger trees the lower branches are usually attacked. Adults prefer trees in young, open stands or the edge trees

of closed stands.

The larvae make galleries in the inner bark on the main stem

and into larger branches, but they rarely extend more than a few

inches below the root collar. They are never in the leader as white

pine weevil and lodgepole terminal weevil galleries are. Look for

the chip cocoons (plate 49, C) on the wood surface. In seedlings

the center of the stem is used for pupation. Adult feeding is like

that of other Pissodes spp. ; they make small holes in the bark of

the stems and branches (plate^4, B).

61
The adult is a small brownish weevil that is difficult to distinguish from other species of Pissodes (fig. 14).

Balsam bark weevil Pissodes dubius Rand.

This insect is common in areas where balsam fir is abundant. It

attacks dead and dying balsam fir and is therefore a secondary

pest. Standing trees are attacked in the lower half and especially

in the lower one-fifth of the bole.

Small punctures for egg laying on the bole, exuding pitch if the

tree is still alive, indicate an attack. Larval galleries are long and

straight or slightly wavy. They radiate from a common point just

beneath the bark. The pupal cell—a wide area at the end of the

gallery—occurs on the wood surface under the bark. The adult

beetle is gray brown and mottled black and white (similar to

fig. 14).

A pine weevil Pissodes affinis Rand,

This weevil sometimes becomes abundant. It breeds in stumps,

logs, and large dying trees. It commonly attacks stands of old

eastern white, red, jack, and Scotch pine. The adults do little

damage to old trees, but may cause some injury to shoots on young

trees less than 10 feet tall.

Larval galleries in the inner bark (plate 50, B) are characteristic of this species. On stumps or dead trees, they start near the

root collar and extend in various directions. The galleries are

narrow, shallow, tortuous, packed with light-brown frass, and

may extend into the roots or up the tree for 2 feet. The pupal pits

at the ends of the tunnels are covered by a chip cocoon (plate

49, C). Adult feeding is typical of Pissodes species; they make

small holes (fig. 14) in the bark on the old growth of branches and

consume as much of the inner bark as they can reach with their

beaks.

Small spruce weevil Pissodes rotundatus LeC.

This is a rare insect infrequently found attacking white spruce

and perhaps other spruces. It prefers young saplings. The larvae

feed under the bark near the root collar ; most galleries are vertical

(similar to plate 49, D), The adult is similar to, but somewhat

broader than, other species of Pissodes (fig. 14).

Pine root collar weevil Hylobius radiéis Buch.

This weevil is the most destructive species in this genus in the

Lake States. It attacks and kills Scotch, red, jack, Austrian, and

62
a few ornamental pines. Eastern white pine is practically immune,

although some are attacked when interplanted with the favored

hosts. Complete stands of pines, especially Scotch pine which

suffers the most once attacked, have been wiped out by the larvae

of this pest. It prefers open-grown trees 2 to 20 feet tall.

Often the first evidence of attack is dying or leaning trees. Look

for entire trees turning yellow (plate 12, A) or brown, or trees

leaning or broken off at the root collar (plate 48, B). The root

collar beneath the duff and soil is commonly constricted (plate

52, D) and irregular larval galleries occur in the bark and cambium of the root collar and primary roots. The soil around the

root collar is pitch-infiltrated and blackened (plate 48, A). Larvae

are in the root collar or in tunnels in soil nearby ; pupae usually

are in earthen cells in the pitch-infiltrated soil.

Adults feed on the bark of branches (plate 34, D) but cause no

important injury. The adults are similar to other Hylobius weevils

(fig. 15)'and require someone skilled in taxonomy for positive

identification.

Root tip weevil Hylobius rhizophagus M.B.&W.

A destructive species locally in Michigan and Wisconsin, this

weevil attacks and kills seedling- to pole-size pines. Closed stands

of pole-size pines are especially susceptible. The insect prefers

jack pine but will attack red and Scotch pine. Eastern white pine

is also injured when grown with the preferred hosts, but it is

rarely killed.

First evidence of attack are flagged, stunted shoots (but with

normal-size needles) scattered throughout the crown. Either a few

inches of the tip or the entire branch can be affected. This

symptom superficially resembles attacks of the Saratoga spittlebug and Scleroderris canker (plate 12, B), but the lack of feeding

scars (plate 33, B) and lack of discolorations beneath the bark

(plate 45, D) distinguishes it. Trees appear tufted and may be

spike-topped (plate 22, D). Proof of weevil attack consists of

finding the larvae or root damage. Look for small roots that are

chewed off ; large ones are debarked or hollowed out and filled with

frass (plate 48, Z)). Larvae do not feed on the root collar. A small

amount of pitch-infiltrated soil may surround the injury. The

pupal cell consists of a shallow excavation in the xylem of the root

base covered by a chip cocoon.

Adults feed on the bark of branches (plate 34, D) of all hosts

but red pine. They will eat the new bark of seedlings, killing some

shoots. The adults are similar to other Hylobius weevils (fig. 15)

and require taxonomic skill for positive identification.

63
Warren's collar weevil Hylobius warreni Wood

This northern species, common in Canada, is known to attack

and kill pines, spruces, fir, and tamarack in Upper Michigan. Polesize trees are particularly susceptible, but all trees more than 2

feet tall may be attacked, especially if growing on wet sites.

Larvae feed in the bark and cambium of the root collar and

large roots. Roots more than 2 inches in diameter are girdled;

small trees may be girdled at the root collar. Injury to pines superficially resembles injury by the pine root collar weevil (p. 62).

Trees turn yellow and die when attacks are heavy (plate 12, A).

However, the larvae of H. warreni form large pitch tubes or

masses at the root collar (plate 48, C) which are not formed by

other weevils.

Adults nibble the bark of roots and twigs (plate 34, D) and

needles of the host, but seldom enough to be destructive. The

adults cannot fly but otherwise are similar to other Hylobius

species (fig. 15) and usually require taxonomic skill for positive

identification.

A pine weevil

Hylobius congener Dalla Torre, Schenkung and Marshall

This weevil occurs throughout the Lake States where it inhabits

stumps and logs of red, eastern white, and Scotch pine. It does not

injure living trees and so is distinguishable from most other

Hylobius weevils which do.

The larvae feed in the bark—the galleries follow the grain of

the wood and are filled with frass (plate 49, D). Look for the

pupal cells, which are diagnostic for this species. Instead of being

on the surface of the wood as in some related species, they are

about l^ inch beneath the wood surface and parallel to the grain.

A short tunnel connects each cell with the surface. This weevil

packs wood chips from the excavation into the old feeding tunnels

and does not form a true chip cocoon like some other weevils do

(plate 49, C).

Adults feed on the bark of logs and slash, causing no important

damage. The adults are similar to other Hylobius weevils (fig. 15)

and require taxonomic skill for positive identification.

Pales weevil Hylobius pales (Herbst.)

This widely distributed weevil attacks several species of pines,

spruces, firs, and junipers, and tamarack. The larvae are of little

importance when they feed in recently cut stumps. However, the

larvae will leave the stumps and invade the roots of living trees

and cause flagging of the branches (as plate 12, B). This flagging

64
is always associated with freshly cut tree stumps nearby. The

adults, too, are important because they destroy seedlings and young

saplings up to 3 feet tall by debarking them. The insect is primarily a Christmas tree pest in the Lake States because of selective cutting, which provides a continuous supply of stumps as

primary breeding material.

Larvae feed in the bark of stumps above and below the ground

line. Chip cocoons covering pupal cells on the wood surface

beneath the ground (plate 49, C) indicate the insect's presence.

Some Pissodes weevils construct similar chip cocoons, but they are

slightly smaller and more compact than those of Hylobius and

occur both above and below ground.

The adults consume the stem and branch bark of seedlings

(plate 47, A) and saplings, preferring eastern white pine. On

seedlings, the heaviest feeding is usually on the stems near the

litter line. On saplings, adults feed on the branches causing the

branch to flag from the injury to the tip. Needles often fail to

elongate on new growth. Stems that are nibbled may exude pitch

(plate 40, B). The adults feed at night and typically cannot be

easily distinguished from the other Hylobius weevils (fig. 15).

Pitcheating weevil Pachylohius picivorus (Germ.)

This insect, uncommon in the Lake States, in injurious in the

adult stage. The larvae inhabit roots and stems of felled and dead

conifers. The adults consume the bark of the stems and branches

of seedlings (plate 47, A) and saplings. Seedlings die and saplings

flag from the branch tip back to the injured area. The symptoms

resemble those of the more common pales weevil, which may also

occur with the pitcheating weevil. The adult Pachylohius closely

resembles Hylobius weevils (fig. 15) but differs by having very

few scattered scales on its upper surface.

Pine gall weevil Podapion gallicola Riley

This weevil differs markedly from all others in the Lake States

because it produces galls on the branches of red pine. It occasionally kills branches but it is important only as an eyesore on

ornamental red pines. The gall appears as an offcenter swelling on

a branch internode behind the new growth. About 1 inch in diameter, it may be oval (plate 27, A) or spherical and have needles

growing from it. Galls farther back on the branch may even be

larger and not attended by needles. Sometimes two or more galls

nearly coalesce.

Podapion galls superficially resemble galls caused by some disease organisms (plates 27, Z), and 28, A and B). However, Poda65
pion galls are found only on the branch internodes of red pine and

contain one to eight small larval cells under the bark (plate 27, B).

A pine twig weevil Magdalis perforatis Home

This weevil sometimes heavily attacks dying branches and slash

of red, eastern white, and Scotch pine. It prefers trees 1 to 12 feet

tall dying from insect or disease attacks, and dead lower branches

of older trees in closed stands. It breeds only in dead material, but

when the weevil is abundant, the adults may cause serious damage

to new shoots of young living trees. Adults feed on the soft green

tissues at the base of needle fascicles leaving small circular holes

on the new shoots (plate 34, A). Heavy feeding destroys many

needle bundles and sometimes stunts shoots.

The larvae feed in recently dead branches. The larval tunnels,

which occur in the pitch from the branch tip back toward the base,

are packed with frass, and may be up to a foot long (similar to

plate 33, D).

The adult weevils, occasionally seen in June and July, are about

l^ inch long, bluish black, and wedge-shaped.

Black vine weevil Brachyrhinus sulcatus (Fab.)

This insect is commonly called the taxus weevil because it is a

common pest of yew (Taxus). It also attacks hemlock. It is most

destructive in commercial landscape nurseries and around homes

where heavily infested trees die.

Both the adults and larvae feed on the tree. Look for adult feeding consisting of notched or partly chewed oiï needles (plate 6, B),

especially in the lower part of the tree. This damage is inconsequential but indicates the pest's presence. The adults feed only at

night so they are rarely seen. The larvae, small curved grubs (fig.

16), injure seedlings and young saplings destroying the rootlets

(plate 47, B), Trees first turn yellow from the shoot-tips back,

then die (plate 13, D), The damage and habits of this insect are

similar to those of the closely related strawberry root weevil, but

the adult female (fig. 17) (no males known) of the black vine

weevil is nearly twice as large (i/^ inch) as the strawberry root

weevil.

Strawberry root weevil Brachyrhinus ovatus (L.)

This insect is very destructive to conifers in nurseries. The

larvae, small white curved grubs (fig. 16), feed on the rootlets of

hemlock, spruce, yew, and arborvitae. The foliage of injured trees

turns pale yellow, then brown. Heavily infested trees die. The

66
adults feed on the foliage only at night. Look for their damage,

which consist of partly chewed and notched needles (plate 6, B).

This injury is harmless to the tree but indicates the insect's

presence. The overall damage and habits of this insect are similar

to those of the black vine weevil, but the adult female (fig. 17)

(no males known) of the strawberry root weevil is only one-half

as large ( 14 inch) as the black vine weevil.

FIGURE 17.—Brachyrhinus weevil adult female. (Photo courtesy of Michigan State University.)

Bark and Ambrosia Beetles

These two groups contain the most destructive insects in North

America. The bark beetles are especially damaging, primarily to

overmature trees. Occasional small outbreaks have occurred in the

Lake States, particularly when man or other agents weaken or

kill trees. The lack of large areas of overmature trees has probably

prevented large outbreaks. Bark beetles attack all parts of the

tree, but usually only if the tree is weakened, dying, or dead.

These beetles are important pests when they hasten the death of

weakened trees and when they attack apparently healthly ones

during population explosions.

67
Bark beetles are difficult to separate without aid from experts,

but their galleries, which are mostly constructed on the inner bark

and surface of the wood, make identification easier. Each genus

and most species make unique gallery patterns (plate 52, A;

fig. 18). Entrance and exit holes and pitch tubes (plates 37, C

and D, and 46, D) are signs of attack. A few species do not make

galleries, but attack shoot tips and cones instead.

68
Many bark beetles are associated with other forest insects and

diseases because they prefer trees weakend by such agents. Wood

borers (p. 73) may also be present in trees infested by bark

beetles. Small, colorfully banded, predatory beetles are sometimes

found in bark beetle infested material.

Ambrosia beetles are similar to bark beetles, but most of them

form galleries inside the wood perpendicular to the surface (fig.

18). Galleries may be straight, winding, or branched. Their galleries are also distinguishable by the presence of a black ambrosia

fungus that lines the walls.

There are more than 50 species of bark and ambrosia beetles in

the Lake States. A few of the most commonly encountered species

are described here.

Red turpentine beetle Dendroctonus valens LeC.

This beetle is the largest species in this genus and the most

widely distributed bark beetle in North America. Outbreaks have

been neither extensive nor severe because the insect usually is in

competition with more aggressive species. In general, it is a secondary enemy of pine and spruce, but on occasion it attacks and kills

apparently healthy trees, preferring pole-size ones but including

all sizes. Red and jack pine are preferred but the beetle will attack

many other conifers including tamarack and firs.

Look for single or small groups of dead or dying trees with

foliage that is uniformly off-color—usually because of other bark

beetles associated with it. Injured trees reveal white-to-yellow

pitch tubes (plate 37, D) up to 2 inches in diameter concentrated

in the basal 6 feet of the tree (plate 37, C). Reddish boring dust

may be present on the bark or ground. If the tree survives, *'cat

faces" (partially healed scars) will occur at the tree base where

the bark has been killed.

The galleries are extremely variable. The egg gallery, on the

inner bark and wood surface, commonly resembles an inverted

FIGURE 18.—Bark and ambrosia beetle galleries. Adult bark beetles excavate

one or more egg" galleries in the bark or wood surface. Larvae, individually

or in congress, excavate distinct types of tunnels or mines away from these

galleries. (Larval tunnels are shown for all but B below, adult entrance

holes are represented by dotted circles). Pupation occurs in cells at the

ends of the tunnels or mines. Eggs are laid in small niches along the

gallery (as in E) or in frass along the gallery wall (stippled areas of A,

B, C, and G). Drawing D is an ambrosia beetle gallery found in the wood

perpendicular to the wood surface (dotted line). Galleries are not drawn to

scale. A, Dendroctonus murranae (p. 70) ; B, Dendroctonus valens (p. 69) ;

C, Dendroctonus rufipennis (p. 11) ; D, Trypodendron sp. (p. 72) ; E, Pityokteines sparsus (p. 72) ; F, Ips pini (p. 70) ; G, Dendroctonus simplex (p.

70) ; H, Phloeosinus sp. (p. 71).

69
''J'' (fig. 18). The larval tunnels are large, broad, tabular areas

commonly extending several feet up or down the stem. The adult

beetles (Vs inch long) are reddish brown and are in the galleries

during the summer. Adults, pupae, and larvae appear as in plate

52, ß.

Pine engraver Ips pini (Say)

The commonest bark beetle on conifers in the Lake States, this

beetle can be found in injured or weakened trees in many conifer

stands. It normally attacks dying trees, dead branches, and slash,

but it will attack and kill trees weakened from drought or other

agents. Eastern white pine is apparently preferred, but the insect

will attack most other pines and spruces.

Look for small patches of dead or discolored trees. The insect

attacks all parts of the tree but sometimes the lower crown may be

spared and survive. Pitch tubes (plate 37, D) rarely form, but red

boring dust is commonly seen on the ground and bark beneath the

entrance holes.

Three to five egg galleries radiate from a central chamber (plate

52, A; fig. 18) depending on the number of females present. Egg

galleries up to 6 inches long are mined generally along the grain

of the wood but most larval tunnels cut across the grain. The darkbrown adult beetles are found in the galleries during most of the

year.

Lodgepole pine beetle Dendroctonus murryanae Hopkins

This beetle attacks jack pine and eastern white pine in the Lake

States but has not been destructive. It prefers stumps, windfalls,

and weakened pole-size trees. Trees weakened by other bark

beetles are often attacked.

On standing trees, look for the attacks on the bole in the lower

2 feet of the crown; on prostrate trees, the attacks are on the

lower side of the bole.

The egg gallery is vertical and 4 to 8 inches long. Larval mines

start out perpendicular to the egg gallery but become parallel a

short distance away (fig. 18). The larvae feed in a group producing mines several feet long up or down the tree from the point of

attack. Characteristic islands of unexcavated bark remain at the

angle where the mines turn. The adult beetles, found in the egg

galleries, are dark brown with reddish-brown wing covers.

Eastern larch beetle Dendroctonus simplex LeC.

Not usually economically important, this insect is one of the

more common bark beetles attacking tamarack. It usually attacks

70
dying and weakened trees, although it occasionally attacks apparently healthy, mature trees. It is a beneficial insect in that it

helps the breakdown of stumps, fallen trees, and forest debris.

Look for the galleries of this insect in dead or extremely weakened tamaracks. Seldom are there pitch tubes (plate 37, C and D)

because of the tree's weakened condition at the time of attack, but

there will be abundant red boring dust on the bark. The egg

gallery (fig. 18) is elongate, vertical, and up to 9 inches long.

Larval tunnels occur in groups of three to six or more and do not

cross one another. Adult beetles (l^ inch long) are dark brown,

often with a reddish cast, and are found in the galleries during

the summer.

Spruce beetle Dendroctonus rufipennis (Kirby)

The most destructive of the spruce bark beetles, this insect

destroys millions of dollars worth of standing spruce yearly in

eastern North America. It attacks all spruces, but it has not yet

been a serious pest in the Lake States because overmature trees

are not plentiful. Even though apparently healthy trees are

attacked, this insect is chiefly found in windfalls and weakened

trees. ^

Look for dead and dying spruces with discolored foliage.

Attacks start on the lower third of the bole (except for the first

2 to 3 feet above the ground) and progress up the bole. There may

be up to 24 attacks per square foot of bark during an infestation.

Pitch tubes (plate 37, C and D) form on the bark if the tree is

alive when attacked. Reddish boring dust is found on the bark

and ground beneath entrance holes.

The egg gallery (fig. 18) is vertical and 10 to 18 inches long;

the larval mines are perpendicular to the gallery, often communal

for a short distance, and many cross one another. The adult beetles

(% inch long) are reddish brown to black and found in the

galleries most of the year.

Cedar bark beetles Phloeosinus spp.

The redcedar bark beetle {P.dentatus (Say)) and the northern

cedar bark beetle (P. canadensis Swaine) are the commonest bark

beetles attacking junipers and arborvitae in the Lake States. They

prefer limbs, stumps, logs, and tops of unthrifty trees.

Look for the galleries under the bark (fig. 18). They are up to

2 inches long and cut across or are oblique to the grain. Small

turning niches occur at the base of the egg gallery near the

entrance hole.

71
Balsam fir bark beetle Pityokteines sparsus (LeC.)

This insect is considered one of the primary enemies of balsam

fir. It also attacks tamarack and spruce. Like most bark beetles,

it prefers dead trees and slash but will attack weakened trees of

all sizes. Look for fading trees with tops dying first. Sap seeps

from the entrance tunnels on the bark.

The egg galleries radiate 1 to 11/2 inches from a central chamber

(fig. 18) across the grain of the wood. Larval tunnels are widely

spaced and mostly constructed along the grain of the wood.

Jack pine tip beetle Conophthorus banksianae McP.

This insect causes extensive shoot tip mortality on pines. It

prefers shoots of sapling jack pine but will attack shoots of red

and Scotch pine saplings, especially if planted near jack pine.

A small pitch tube (plate 37, A and B) about 1/2 inch behind the

bud or new shoot is a sure sign of attack. After June these injured

shoot tips turn red. Elongating shoots droop (plate 37, B). The

dead shoot tips fall to the ground in autumn. A small, dark-brown

bark beetle or a group of small, white larvae is found in the shoot

tip during the spring and summer.

Attacked branches terminate abruptly where the tips have

broken on. Branches and terminal shoots become forked where

lateral buds develop and assume dominance.

The beetle Cimberis elongatus (LeConte) is sometimes associated with C. banksianae. This insect kills buds and shoots

directly itself but it often also feeds in the new shoot tips (as plate

37, A) already attacked by Conophthorus. It injures the tissues

near the tip of the shoot. The small larva lives in the bud, in the

needle inside the sheath, or in the shoot. Conophthorus, in contrast, feeds near the base of the injured new shoot.

A few lesser known bark beetles (Myelaborus and Pityophthorus) also cause injury similar to Conophthorus, but the adult

insects are needed for precise identification and should be examined by a taxonomist.

A gall beetle Unknown species

Little is known about this beetle except that it causes galls at

the base of shoots on arborvitae (plate 27, C). Small shoots above

the gall flag and drop off. It is not considered to be economically

important.

Ambrosia beetles Trypodendron sp., et al.

The striped ambrosia beetle (T. lineatum (Oliv.)) and others

are important pests of coniferous trees to be used for wood pro72
ducts. They prefer dying and injured trees, or recently cut logs.

They do not attack seasoned wood.

Look for pin holes in the wood leading to galleries lined with a

black fungus called ambrosia. The wood has to be cut to see the

straight or branched galleries and short larval cradles (fig. 18).

Wood Borers

This group consists of several families of insects that bore into

and destroy the woody tissues of conifers. Included here are the

flatheads, roundheads, horntails, and powder-post beetles. Most of

these are "secondary" insects ; that is, they attack only trees that

are weakened, dying, or dead from other causes. Some of these

borers can attack a dead tree only if it has fresh bark attached.

Other ones, like the powder-post beetles, prefer dry, well-seasoned

wood so they are mostly a problem in forest products.

Several species of wood borers can inhabit the same host simultaneously because their requirements are similar. Bark beetles

(p. 67) may also be present at the same time.

Flatheaded borers Melanophila spp., et al.

At least 30 species of flatheaded borers attack conifers of all

kinds in the Lake States. Important genera include Melanophila,

Buprestis, Chalcophora, Dicerca, and Brachys. The larvae, which

cause the damage, are somewhat flattened in the area of the thorax

behind the head—hence the name "flatheads" (fig. 19). The adult

beetles (fig. 20) are called metallic wood borers because many are

irridescent and brightly colored.

FIGURE 19.—Flatheaded wood borer larva. (Photo courtesy of

Michigan State University.)

73
The best known and most impo^-tant flathead of conifers in the

Lake States is the hemlock borer, Melanophila fulvoguttata (Hartís). Principally a pest of eastern hemlock, it also attacks dying

eastern white pine, tamarack, balsam fir, and red, white, and

black spruce. It is generally a local pest but sometimes attains

epidemic numbers when trees over large areas are weakened or

killed by drought, windthrow, insects, or diseases.

FIGURE 20.—Flatheaded wood borer adult. (Photo courtesy of

Michigan State University.)

Attacked trees first show yellowing of shoot tips, then dieback

of the uper crown. Look for larvae and their characteristic galleries on the surface of the sapwood beneath the bark (plate 50, A).

The galleries are larger than those of bark beetles and differ from

roundheaded borers by being packed tightly with fine dark excrement and wood particles. From the outside, the bark may show

woodpecker holes (plate 46, C) or small oval holes (YQ to l^ inch

diameter) through which the adult beetles have emerged. Armillaria root rot may be associated with the attack and appear as

mushrooms at the tree base (plate 44, B) or as mycelial fans (i.e.,

white patches of fungal tissue) or black rhizomorphs (threads)

under the bark.

Roundheaded borers Monochatnus spp., et. al.

Three species of Monochamiis and at least one species of Prionus

attack conifers in the Lake States. The wood-destroying larvae

(plate 49, B) are not especially ñattened in the thoracic area and

are thus distinguishable from the closely associated flatheaded

74
borers (plate 50, A). The larvae and damage are similar for all

species discussed here.

The most common roundheaded borer that attacks conifers in

the Lake States is the white-spotted sawyer, Monochamus scutellatus (Say) (fig. 21). Other frequently observed species are the

FIGURE 21.—Roundheaded wood borer larva. (Photo courtesy of

Michigan State University.)

northeastern sawyer, M. notatus (Drury), and the balsam fir

sawyer, M. marmorator Kby. The adults are large beetles with

long antennae (fig. 22). The white-spotted sawyer and the northeastern sawyer attack dead and dying pines, spruce, and balsam

fir, and perhaps other conifers. The balsam fir sawyer attacks some

green and standing, but probably weakened or dying, balsam fir.

Live but infested trees lose their color and die from the top

down. Look for the larvae (fig. 21) or their characteristic gailaries

and tunnels beneath the bark (plate 49, A and B). The gailaries

and tunnels are large, generally irregular, and may contain coarse,

loosely packed frass and excelsior-like wood shavings (plate 49, B).

Boring dust may accumulate in piles (plate 51, D). Oval holes in

the wood indicate tunnel entrances (plate 49, A). From the outside, the bark may show woodpecker holes (plate 46, C) or round

holes (l^ to %6 inch diameter) through which the adult beetles

have emerged. Associated pests may include bark beetles (p. 67),

flatheaded borers (p. 73), and shoestring root rot (p. 89).

Adult sawyers (fig. 22) also injure conifers by feeding on the

bark of twigs. The shoot tips sometimes flag above the wounds.

This flagging resembles that caused by several other insects and

diseases but can be distinguished by the nibbled bark (plate 47, D)

below it.

75
Pine-bark borers (Acanthocinus spp. and Stenocorus spp.) are

often found under the bark of pine. Neither are injurious because

they feed only in the bark of dying or dead trees. If present during

extensive bark beetle outbreaks, Acanthocinus is actually beneficial

because it destroys the inner bark, thereby preventing development of bark beetles. The unusual pupal cell (plate 52, C) distinguishes these insects from other borers.

F-496927

FIGURE 22.—Roundheaded wood borer adult.

The broadnecked root borer, Prionus laticollis (Drury), is sometimes observed in the wood of pines. Though seldom destructive on

a large scale it can be destructive locally. It tunnels in the roots

of living pines but also feeds in stumps and logs. The yellowishwhite larva is up to 2i/^ inches long, and pointed on the rear end,

which distinguishes it from other related borers.

Horntails Vrocerus spp.

Of several horntails in the Lake States, the white-horned horntail, Vrocerus albicornus (F.), is the most frequently observed in

conifers. It attacks extremely weak or dead pines, spruces, and

cedar.

76
The larvae damage wood that may be used for lumber. The galleries are made entirely within the wood and can only be observed

by sawing or splitting infested logs. Look for the characteristic

galleries that are round (up to 14 inch) in cross section and packed

behind the larvae with fine whitish frass (plate 50, C). Circular

holes in the wood surface are where the adults emerge.

The whitish larvae of these wasp-related insects are rounded in

cross section, up to % inch long, and have a small pointed spine on

the rear end.

Powder-post beetles Stephanopachys spp., et al.

Various species of powder-post beetles destroy coniferous wood

in the Lake States. They attack and breed in well-seasoned wood

and bark and are especially important in furniture, lumber, or

other wood products.

These insects are so named because the wood or bark they feed

on is gradually reduced to a fine, flourlike powder. Their presence

is indicated by pin holes (plate 50, D) in the wood. Look for a

fine, powdery sawdust that sifts almost constantly from these

holes. Their damage can be distinguished from bark beetles by

their irregular tunneling inside the wood or bark, and not in

regular patterns along the cambium.

The adults are small (I/5 to V2 inch long) brownish beetles; the

larvae are smaller and whitish.

Ants and Termites

Ants and termites are social insects that live in colonies in wood

or in the soil. Subterranean termites both excavate and eat wood.

Carpenter ants only excavate wood for a domicile and forage forth

from this home to collect food. Other species of ants build large

mounds and destroy all vegetation in the vicinity of these nests.

Some other species are indirectly destructive because they protect

colonies of tree-destroying aphids in order to feed on the aphids'

honeydew. Still other ants are beneficial because they prey on

forest insect pests.

Black carpenter ant Camponotus pennsylvanicus (DeGeer)

This carpenter ant destroys living conifers and wood products.

It commonly infests northern white-cedar and balsam fir. The

adults excavate large cavities in the heartwood of pole and sawtimber trees.

Damage consists of irregular galleries (plate 51, B) that honeycomb the wood and sometimes nearly hollow out the center of the

77
tree. The walls are smooth and not coated with a whitish substance

—a characteristic of termites. The galleries are kept clean of

debris. Coarse, fibrous borings are extruded from the galleries

through small ''pushouf' holes (as plate 51, D). The adult ants are

black and up to Y2 inch long.

Allegheny mound ant Formica exsectoides Forel

This ant sometimes destroys seedling and sapling conifers—

especially if its moundlike nest is located in plantations or clearings. Pines, spruces, cedars, and other conifers from 2 to 15 years

old may be killed if near the ant nests. These ants commonly kill

all vegetation, except pole-size or larger trees, up to 20 feet around

their nests. Formic acid injected into the bark by the adult ant

kills the trees. Before the tree dies, a small lesion or gall resembling

a fungus canker develops where the tree was injected. This ant or

closely related species such as the thatch ant, F. obscuripes Forel,

builds large earthen mounds or nests that may be 2 feet high and

6 to 8 feet in diameter (fig. 23).

Eastern subterranean termite Reticulitermes flavipes (KoUar)

This widely distributed termite is an occasional pest of conifers

in the Lake States. Although usually associated with dead wood

and forest products, it sometimes attacks living trees.

Damage consists of irregular galleries that more or less honeycomb the wood (plate 51, A), Most of the galleries follow the

softer spring wood. These cavities may be coated with a hardened

whitish substance and lined with soil and debris. Termites always

leave a shell of surface wood to protect them from dry air and they

do not push wood particles to the outside like ants and roundheaded borers do. Earthen shelter tubes associated with the damage are sure signs of termites. The majority of the termites in the

colony are whitish and about ^4 inch long (plate 51, A).

White Grubs

White grubs Phyllophaga spp.

White grubs are the larvae of the familiar Junebug or May

beetle. The larvae of the genus Phyllophaga and a few related

genera are sometimes serious pests of young conifer plantations.

They feed on the roots and injure all species of conifer seedlings

and very young saplings up to about 4 years after planting. Most

seriously attacked are first- and second-year plantings established

in open grassy fields where white grubs are abundant at the time

of planting.

78
i; rr

#1 .

'•-;>/ :Ä^

<V5^/

^^^..,>^^

FIGURE 23.—Mound ant nest.

F-521449

79
Seedlings and young saplings that are attacked become discolored in late summer and early fall and die. These reddish-brown

dying and dead trees resemble drought-killed or diseased trees,

but digging exposes their damaged lateral and tap roots that have

the tips chewed off or girdled (plate 47, C).

FIGURE 24.—White grubs. (Photo courtesy of Michigan State University.)

White, C-shaped larvae (fig. 24) up to 1 inch long are found in

the soil near the seedlings during the summer and fall. The adult

beetle rarely injures conifers; it usually feeds nocturnally on the

leaves of deciduous trees near its breeding site.

CONE INSECTS

Cone beetles, moths, and flies destroy conifer seeds directly by

feeding on them, or indirectly by feeding in and killing part of

all of the female flowers (cones). The cone insects of pine and

spruce are best known because these trees are most commonly

planted.

80
The cone insects discussed in this section feed within the cones

during most of the larval period. Certain other insects feed on

cones only incidentally and are more important as defoliators or

shoot borers ; e.g., the spruce budworm (p. 31). A few insects feed

on the inner or outer surfaces of the cone scales but are not cone

pests. These, however, may be encountered along with primary

cone insects. When examining injured cones to identify primary

cone insects, one should keep in mind that different cone insects

can attack a cone at the same time or in sequence.

Cone Beetles

Cone beetles are easily distinguished from other cone insects by

their black, Vs-inch long adults, or their smaller, white, C-shaped,

legless larvae, both of which may be found in attacked cones. There

is one important species on red pine and one on eastern white pine.

Red pine cone beetle Conophthorus resinosas Hopk.

This insect is the most destructive pest of red pine cones in the

Lake States. Although variable from place to place and year to

year, it is commonly severe enough to make commercial seed collecting uneconomical. Second-year red pine cones are preferred,

but current-year's red pine shoots and occasionally second-year

jack pine cones are attacked by the larvae. Red pine shoots are

also attacked by the adult beetle for overwintering quarters.

Attacked cones are smaller than normal (plate 53, D) and dead.

Look for a groove (plate 54, A) at the base of the cone leading

from a hole in the axis to the outer margin of the cone. Internally,

the axis is mined longitudinally. Also, the seeds are destroyed and

the cavity contains fine granular frass.

Shoots used by the adults for overwintering are damaged in the

fall. Look for green shoot tips that have a small hole just behind

the bud (similar to plate 29, B), These shoot tips break oif and

fall to the ground before winter. The adult beetle is found in the

bud of the severed shoot.

White pine cone beetle Conophthorus coniperda (Schwarz)

A pest of eastern white pine cones, this insect may damage the

seed crop badly in years when only light or moderate seed set

occurs. During severe infestations many shoot tips are also killed.

Damaged cones contain a hole at the base that leads to a tunnel

up the axis (plate 53, C). Seeds are destroyed and the cavity contains fine granular frass. After July, look for the cones that have

aborted and fallen to the ground.

81
Cone Moths

Cone moths are small moths whose larvae feed in conifer cones.

The larvae are typical caterpillars having three pair of regular

legs in front and five pair of false legs along the body, v^hich distinguish them from other cone insects. Pupae, cast pupal skins,

and cocoons may sometimes be found inside the injured cone or

outside nearby.

Red pine coneworm Dioryctria disclusa Heinrich

This insect infests second-year red, jack, and Scotch pine cones,

but is only locally destructive. Most infested cones die, but a few

survive and produce seeds. Usually each larva attacks two cones

before it matures. Early larval feeding is confined to male flowers

(plate 53, A) until pollen is disseminated. ^

Cones attacked by this insect are distinguishable from those of

other pine cone insects by a silk web spun between the cone and

nearby needles and a single entrance hole near the cone base (plate

54, E). Look for a heavy accumulation of reddish-brown frass in

the webbing. The cone contains a large internal cavity in the seedbearing region (plate 54, F). The cavity may become partially

filled with dried resin, frass, and webbing.

A red pine coneworm Eucosma monitorana Heinrich

This insect is occasionally abundant in red pine stands. Before

it matures each larva attacks two cones and stops seed development within them. There may be 25 or more young larvae in the

first cone at the beginning of an attack, and up to five in the

second cone.

Damaged second-year cones wither and become discolored. Look

for numerous tiny holes in the cone exterior or one or more larger,

oblong ones between the scales in the side of the cone (plate 54, B).

A small amount of frass may protrude from the holes. There is no

webbing. Internally there is extensive tunneling in the seeds and

tissues, plus a mixture of resin and frass (plate 54, C). A stub

remains on the branch if the cone aborts.

A pine seed moth Laspeyresia toreuta (Grote)

This species is a minor pest of second-year red and jack pine

cones in the Lake States. It is the only pine cone pest that destroys

seed without injuring the cone. Some seeds escape attack. The cone

scales are not injured during feeding so the cones open normally

and release undamaged seeds.

82
Detection of this insect is difficult because the cones appear

normal and the entrance holes between the scales cannot be seen

with the naked eye. The cone must be opened to be certain of attack.

Inside, look for clean tunnels and mined-out seeds (plate 54, G)

tightly packed with debris.

Spruce coneworm Dioryctria reniculella (Grote)

This is a relatively common insect on white, black, and blue

spruce, and an occasional pest of balsam fir, Douglas-fir, tamarack,

and pine. It is particularly destructive on small, open-grown trees ;

both the cones and young terminal shoots are hollowed out by this

pest. Shoots are attacked when cones are scarce.

Look for the cone damage, which is striking and readily recognizable when feeding is near completion. Then only a shell remains

consisting of the outer parts of the scales held together with silk.

Coarse frass in webbing is abundant on the cone surface (plate

53, ß). Mined shoots of new growth are attended by a delicate silk

tent covered with coarse frass (plate 10, D). These injured shoots

curl as they develop and form a "pigtail" (plate 31, B),

Spruce seed moth Laspeyresia youngana (Kft.)

This insect is a common pest of white, red, and blue spruce. It is

an important seed destroyer in years when cones are scarce—

sometimes all cones may be infested. As in the case of the pine

seed moth, seeds that are not eaten are shed normally.

Damage consists of destroyed seeds, mostly near the cone base,

and a hollowed-out cone axis. Usually one larva, but sometimes

more, inhabit a cone. Frass is packed in the tip of the tunnel and

in the depleted seed coats. Look for an exit hole near the base of

the cone, attended by a short silk tube leading to the outside

between the scales. This tube, which is made just before pupation

in the fall, is diagnostic for this insect.

Fir coneworm Dioryctria abietella (D. & S.)

This insect infests cones, shoots, and bark of many different

conifers but fir and pine are commonly attacked. It may cause

heavy seed loss. Young larvae feed in cones previously infested by

other species; older larvae each directly attack one or more cones.

Cones attacked by this insect show frass-filled webbing (plate

54, D) connecting the cone and adjacent needles and one or more

ragged holes in the side of the cone. The interior may be tunneled

extensively and may contain some webbing but is generally free

of debris.

83
Cone Flîes

This group consists of small midges and flies that attack the

seeds of conifer cones. The larvae, which cause the damage, are

very small legless maggots, distinct from other cone insects. A fev^

species of cone flies feed in cones but do not injure the seeds. Such

species are usually found feeding on or in the scales of the cone.

Spruce cone maggot Pegohylemia anthracina Czerny

This is the commonest fly attacking v^hite spruce cones in the

Lake States. In years when cones are scarce, all of the cones in

an area may be infested by this pest.

There is little evidence of attack from the outside, except for

small exit holes (similar to plate 54, B) on the sides after the

larvae have departed in July. Internally, the damage is evident as

one or more narrow tunnels that start near the cone base and

spiral around the axis through the developing seeds toward the

cone tip. The tunnels are filled with frass and resin.

A red pine cone midge Rubsaamenia sp.

This little-known insect sometimes causes minor damage to red

pine cones. It is capable of infesting cones by itself but it usually

inhabits cones already attacked by other insects.

Damaged cones exude resin that crystalizes into white flakes

between the shriveled scales (plate 54, H). Internally there is no

tunneling or debris (plate 54, /).

NONINSECT MALADIES EASILY CONFUSED

WITH INSERT DAMAGE

Before one can properly identify insect damage, it is necessary

to rule out noninsect damage that looks as if it were caused by

insects. So, as a guide, various groups of noninsect maladies are

described below. Included are those commonly encountered and

some that are associated—or easily confused—with insect damage

in the Lake States.

Natural needle fall should not be confused with any malady.

Tamarack is the only conifer in the Lake States that sheds all its

needles annually. The annual yellowing and dropping of tamarack

needles is a natural physiological function not to be confused with

yellowing caused by insects or diseases. All other conifers in the

Lake States retain their needles from 2 to 7 years, depending on

the species. The oldest needles nearest the stem turn yellow and

are shed each fall, but never all at one time.

84
Diseases

Diseases are caused by living pathogens—mostly fungi—that

injure conifers. Many disease-causing organisms produce signs

and symptoms similar to insect attack. Like insects, a disease

organism can cause more than one symptom. Typically, diseases

kill tissues (necrosis), retard development (atrophy), or cause

overgrowths such as galls or cankers (hypertrophy). Disease injuries differ from insect injuries by not having the insect or insect

artifacts and debris. Insects, hov^ever, are frequently associated

with diseases—especially the wood borers, bark beetles, and others

that attack weakened trees. Such insects should be recognized as

secondary pests and not the primary cause of the host's ailment.

Also, a primary insect may be attacking the host along with a

disease, thus the insect may mask the effects of the disease or

vice versa.

Foliage diseases

Several sooty molds (Dimerosporium spp., et al,) blacken the

foliage of conifers making them appear as if they were exposed to

dense smoke (plate 12, D), These molds develop on honeydew of

aphids and scales (p. 41) and near the ''spittle'' of spittlebugs

(p. 37). Presence of sooty mold is a good sign of one of these pests,

even after the pests have left the host. Although the sooty leaves

are unsightly and interfere slightly with photosynthesis, this

fungus does not injure the tree.

Many diseases infect conifers and cause needle rusts, needlecasting, or drooping. Needle rusts {Coleosporium spp., et al,)

cause old needles of pine to die and be shed prematurely. These

rusts sporulate in the spring or early summer and form yellow,

white, or orange pustules on the needles (plate 15, A and B). These

pustules, unless examined closely, may be mistaken for aphids,

scales, or sawfly eggs.

Brown spot, Scirrhia acicola (Dearn.) Siggers, is a common

needle blight on pine seedlings and saplings. In tlie Lake States,

it is particularly damaging on young Scotch pines where it causes

needlecast. On young trees, the fungus primarily affects only the

foliage within 18 inches of the ground—especially on the north

side of the tree (plate 12, C). The infected needles, which are

encircled by a brown band, can be found beneath the tree and thus

may be used to distinguish this disease from an insect defoliator

that would consume them.

The needlecast disease Hypodermella ampia (Davis) Dearn., is

a common disease of jack pine. Infection may be severe enough to

cause all the old needles to die and drop. This disease may super85
ficially resemble a scale infestation at first glance. In the spring

and early summer, the old needles contain light buff-colored areas

with one or more short, dull-black, elliptical spots (hysterothecia)

(plate 15, C) that resemble scale insects.

Lophodermium needlecast, Lophodermium pirmstri (Schard. ex

Fr.) Chev., causes partial to complete defoliation of red, Scotch,

and jack pine. Infected trees drop their needles, which, if found,

will distinguish the injury from insect defoliation. Infected needles

contain hysterothecia (similar to plate 15, C) that should not be

mistaken for small scale insects.

There are several diseases known generally as ''needle droop*'

that are of unknown cause. Symptoms are yellowing and browning needles bent downward or drooping from the base (plate 6, A).

This injury resembles injury from the pine chafer (p. 24), an

unknown midge (p. 51), and the pine needle sheathminer (p. 34).

See these specific maladies for specific identifiers.

Branch and stem diseases

The important branch and stem diseases of conifers are the rusts

that sometimes produce cankers, witches-brooms, or galls, or all

three. The symptoms of these diseases resemble symptoms of

several stem-feeding and sapsucking insects.

Scleroderris canker (Scleroderris lagerbergii Gremmen) is one

disease responsible for the widespread and severe dieback of conifers in nurseries and young plantations in the Lake States. This

pathogen commonly infects red and jack pines; less commonly, it

infects eastern white pine, Scotch pine, black spruce, and white

spruce. The injury is most severe in depressions and frost pockets.

Symptoms of flagging and top kill on red pine from scleroderris

canker look exactly like injury from Saratoga spittlebug feeding

(as plate 12, B). It is possible to have the disease and the spittlebug

together, but the spittlebug injury can be easily identified by

scraping off the bark and looking for reddish feeding scars (plate

33, S). The disease can often be identified by examining the dead

tissues at the point of attack (see below). New shoots sometimes

droop on infected branches giving the impression of localized frost

injury (plate 30, D). Symptoms on jack pine are usually different;

entire trees may die without flagging first, thus resembling injury

from other diseases, pine root collar weevils (p. 62), or bark

beetles (p. 67).

The usual symptom of Schleroderris is a small, discrete, sunken

area or canker on the stem or branch. A diagnostic feature of this

disease is the characteristic yellow-green discoloration under the

bark in the zone between living and dead tissues (plate 45, Z)). Look

86
for this sign by scraping away the bark behind the flagged portion

of the branch or at a canker.

White pine blister rust (Cronartium ribicola J. C. Fischer) is

an important disease of eastern white pine and can severely damage the host in areas where the local climate favors establishment

and spread of the disease. First the needles are infected and then

the branches flag, a symptom that resembles injury from Saratoga

spittlebug and pine spittlebug (plate 12, B). Cankers develop on

the stems (plate 43, G). Old cankers appear as dead areas on the

bark and are associated with bark beetles and wood borers.

Commandra blister rust (Cronartium commandrae Peck) occasionally attacks jack, Austrian, and Scotch pines, but is seldom a

serious disease in the Lake States. The disease is manifested by a

spindle-shaped swelling on the stem that is covered with orange

blisters in May when mature (plate 43, D). In large stem infections, resin usually exudes from the canker. Resin flow often

increases as a result of feeding on the infected bark by squirrels

and porcupines. Insects such as the Zimmerman pine moth (p. 56),

bark beetles (p. 67), and wood borers (p. 73) may be associated

with the injured tissues.

The eastern gall rust (Cronartium quercuum (Berk.)) is common on 2-and 3-needle pines in nurseries, plantations, and natural

stands in the Lake States. It is found primarily on jack and Scotch

pines, but is also found on Austrian pine. Red, white, and black

oaks are alternate hosts of the fungus. The disease is readily

detected by its globose galls on pine (plate 28, A and B), Galls

developing on the main stem may kill the host, especially if it is a

seedling. Branch galls kill the branches or subject them to easy

breakage. The gall resembles the gall of the pine gall weevil (plate

27, A) but the latter is found on red pine. The Zimmerman pine

moth commonly attacks the galled areas of injured pines; attacked

trees show frass and pitch exudations (plate 41, A). The insect

does no form galls but its feeding in the gall may hasten the death

of the branch or tree.

The cedar-apple rust (Gymnosporangium juniperi-virginianae

Schw.) produces galls on eastern redceder and other junipers. It

is primarily a pest of ornamental trees, usually only spoiling their

appearance but occasionally becoming serious enough to retard

normal development or even kill the tree. The galls may be up to

1 inch in diameter (plate 28, C). Before maturity, they are greenish brown with depressions on the surface. During mid- to late

May the galls develop numerous orange, conspicuous, gelatinous

growths called spore horns (plate 28, D) that may be IV2 inches

long.

87
Cedar-quince rust (Gymnosporangium clavipes Cke. & PK.)

makes swollen, elongate, spindle-shaped galls in the branches of

several juniper species. Diseased twigs become swollen and deformed. The gall enlarges yearly as the fungus remains active for

many years. During rainy periods in April and May, orangecolored gelatinous masses called spore horns appear on the gall

(similar to plate 28, Z)).

Sweetfern rust (Cronartium comptoniae Arth.) is a common

disease of red, jack, Austrian, and Scotch pines in the Lake States.

Sweetfern (fig. 10) and sweetgale are the alternate hosts for this

fungus that causes cankers that kill many young trees. Surviving

trees become malformed along the stems and often harbor decay

fungi that cause heart rot, and secondary insects such as bark

beetles and wood borers. The symptoms on seedlings are elongate

swellings (plate 27, D) that resemble galls of the pine gall weevil

(plate 27, A).Older trees have elongate grooves (plate 42, B) in

the bark resembling callous growth following a lightning strike.

Hemlock twig rust is a conspicuous disease that sometimes kills

hemlock, especially in nurseries. The pathogen kills new shoots

and causes them to curl into pigtails that resemble larch sawñy

oviposition injury (plate 31, B).

Witches'-broom rusts (Melampsorella spp., et al) cause broomlike malformations on conifers, which may be associated with

galls, swellings, or cankers similar to (plate 44, D). Shoots infected

by witches'-brooms are dwarfed (plates 43, B, and 44, A) and the

needles are sometimes discolored. Old witches'-brooms are without

needles. Many kinds of insects may live inside a witches'-broom.

Many kinds of fungi cause rots or decays in conifers. Among

the most important are those that destroy the heartwood of conifers causing weakening of the tree and loss in volume. Advanced

decay appears as soft, punky heartwood (plate 51, C). Decay in

standing trees is commonly evident from conks (fruiting bodies)

growing on the sides of trees. Carpenter ants may be associated

with rots and live in the diseased portions (plate 51, B),

Root diseases

Two root diseases are commonly associated with insects of conifers. Fomes annosus root rot, Fomes annosus (Fr.) Cke., is potentially an important pest of red pine in the Lake States, particularly in 20- to 30-year-old plantings on formerly cultivated land.

This fungus commonly attacks trees weakened by insects, although

it can kill trees by itself. Infected trees often die in patches so that

herbaceous and woody weeds cover the area as a result of the

opening.

88
Fomes annosus root rot can be recognized by the fruiting bodies

(conks) attached to the bases of dying trees or stumps (plate

44, C). The conks differ in size and occur under the duff. Remove

the duff and look for irregular fruiting bodies that are tan, brown,

or reddish brown above and chalky white below. Needles and twigs

may be incorporated in the conks, which are difficult to tear. The

pores on the undersurface are large enough to see with the naked

eye and the texture is rubbery or leathery. Very young conks may

be mere white buttons on the roots or stem.

Shoestring root rot Armillaria mellea (Vahl ex. Fr.) Kummer,

infects most conifer species in the Lake States, especially plantation trees weakened by insects and other agents. It can, however,

attack and kill healthy trees and is especially troublesome in stands

where broadleaf trees have been felled recently. Wood borers and

bark beetles are associated with Armillaria-injured trees.

Infected trees show typical decline in vigor and growth, followed by yellowing of the foliage and death of the tree. Resin

exudes from the root collar and infiltrates the surrounding soil.

White mycelial fans can be found under the bark at the base of

the tree. Reddish brown or black, cylindrical, rootlike rhizomorphs

grow on the root surfaces under the soil. The fruiting body (mushroom) appears in September or October, usually in clumps from

the base of the standing trees or stumps (plate 44, B).

Animals

Warmblooded animals seldom seriously injure conifers but their

damage often closely resembles or is identical to damage done by

certain insects, particularly bark beetles and shoot and root borers.

These insects may also attack a tree damaged by animals.

Birds

The yellow-breasted sapsucker injures sapling- and pole-size

conifers. It favors hemlock but pecks Scotch pine, and often feeds

repeatedly on a favorite tree until it becomes riddled with holes.

The circular holes resemble bark beetle holes at first glance, but

are shallow and arranged in horizontal rows around the tree (plate

46, A and B), Insects such as the Zimmerman pine moth (p. 56)

are sometimes attracted to and attack sapsucker-injured trees at

the point of injury.

Woodpeckers cause minor injury to conifers. Their feeding,

however, indicates that boring insects are present and thus the

tree is already weakened or dead. They make conical holes (1/4

inch or larger) in the bark (plate 46, C) trying to reach wood

borers in tunnels and galleries beneath the bark.

89
The pine grosbeak, when abundant, can injure stands of young

pines and spruces by feeding on buds and breaking new shoots.

Young terminals may be broken (as plate 35, B) by grosbeaks

resting on them. Debudded and broken terminals develop into

crooked and forked trees similar to trees injured by shoot moths

(p. 53).

Mammals

Mice, pocket gophers, rabbits, and porcupines cause damage

that at a distance resembles injury from the pine root collar weevil,

pine root tip weevil, and Zimmerman pine moth. These mammals

gnaw the stem and major roots stunting growth, discoloring foliage, and causing death by girdling. Bark removed in patches and

toothmarks are signs of damage by mammals. The location and

size of the toothmarks help determine the pest. Mice, gophers, and

rabbits, which have small teeth, gnaw near the base of the tree

(plate 45, A), though rabbit gnawing may be a foot or more from

the ground; porcupines, which have larger teeth, usually gnaw

in the upper crown (plate 45, ß).

Squirrels removing cones commonly cause the shoots above the

cone site to flag as if damaged by shoot-boring insects. Ripped

tissues, however, provide evidence of cone removal by squirrels

(plate 35, D). Shoots may be scattered on the ground beneath the

tree. Squirrels occasionaly gnaw on disease cankers also.

Deer sometimes injure conifers. Many conifers, especially cedars,

are browsed by deer when other food is scarce. Twig tips of

browsed trees on the lower 5 feet have splintered, ragged ends.

Heavily browsed young trees become crooked and misshapen. Deer

also pull the needles off young pines causing injury that resembles

sawfly feeding (p. 9). Male deer injure an occasional tree, usually

a small sapling, by rubbing their antlers against the bark. This

"buck rub" appears as shredded bark on one side of the stem,

usually within 3 feet of the ground (plate 45, C).

Bears occasionally rub, gnaw, or chew the bark of large saplings

and poles. They usually strip the bark vertically with their teeth

or claws.

Man, directly or indirectly, causes more injury to conifers than

any other mammal. Climbing trees, he breaks branches and scars

the bark. When collecting cones, he rips the shoot tissues (as plate

35, D) and kills the shoots. With snowmobiles or other vehicles,

he drives over young conifers and skins off their bark in a manner

resembling buck rub (plate 45, C). Often an entire row of pine

or spruce may exhibit this symptom. During logging, equipment

and vehicles (including horses) crush seedlings and damage

90
branches and boles, predisposing them to secondary insects and

diseases.

Other Agents

Damage from physical or mechanical causes sometimes resembles insect damage. Abnormal temperatures, water, weed killers,

and nutritional agents are most often at fault. The absence of

insects or lack of frass, emergence holes, tunnels, etc., is usually

enough to rule out insect damage. Note, however, that secondary

insects such as borers and bark beetles may be present because they

attack trees weakened or dead from any cause.

Abnormal temperatures

Perhaps the most common temperature malady is frost damage.

Frost causes different kinds of injury depending on the time of

year and susceptibility of the host. Greatest injury is caused by

late spring frosts—ones that occur during the period of development of the tender new shoots. Young trees are often harder hit

than older ones. Spruces and balsam fir are particularly susceptible. The most conspicuous injury of late spring frost is the discoloration, wilting, and death of the new shoots (plate 30, D).

The pith of frosted shoots usually turns black or dark brown. The

trees recover but may develop forks and crooks. Trees repeatedly

frost injured become stunted and bushy. Frost can also kill cones.

Although rare in the Lake States, high temperatures can kill

needles and shoots of conifers causing needle browning and flagging damage similar to that caused by sucking insects. Fire, of

course, may also kill the tree or scorch the foliage in the lower

crown. The presence of charred bark would distinguish it from

insect damage.

Winter drying or needle burn is caused by excessive transpiration from warm winds in winter. The needles turn yellow and

resemble needles injured by sucking insects. Eastern white pine is

especially susceptible.

Harmful chemicals

Oils, herbicides, and insecticides can cause ^'needle burn" and

occasionally needle droop (as plate 6, A but more severe) when

improperly or excessively applied. Usually the needle tips are

affected, but entire needles may yellow and drop prematurely. This

damage may resembré the pine chafer or sap sucking insects at

a distance.

Roadside conifers are commonly injured by salt spray. Eastern

91
white pine is particularly susceptible; blue spruce and Austrian

pine are highly resistant. Injury shows up in early spring, when

the conifers appear from a distance to have been injured by an

outbreak of sapsucking or tip boring insects. Look for injured

needles that are bright orange yellow for various distances from

the tips down. The side of the tree facing the road or highway is

almost always injured the worst. Only the lower part of the tree

is injured on tall trees. The symptoms diminish by summer. Herbicides sprayed on conifers along roadsides produce similar symptoms, but the damage usually occurs later in the summer. Because

most conifers can tolerate moderate dosages of herbicides, they

usually recover by the following year.

Conifers are very sensitive to industrial smoke and fumes. Dusts

and metallic fumes cause only minor damage, but sulphur-bearing

gases are highly destructive. At a distance the injury resembles

damage from sucking insects or the pine root collar weevil. Smoke

damage is usually downwind from a smelter or industrial plant.

Look for trees, usually in a group, with bright red-orange needles ;

or bare trees; or trees with sparse foliage. Lightly injured trees

may recover, but growth is stunted. The needles turn brighter red

than winter-burned needles, and the damage develops more slowly

or later in the year.

Air polution is the cause of chlorotic dwarf disease of eastern

white pine. Affected trees have stunted roots and shoots, and short,

mottled, needles that are shed prematurely and resemble injury

from aphids or scales (plate 13, B). New foliage is light green,

becomes mottled, and may exhibit tip burn.

Abnormal water conditions

Drought can both retard growth and kill trees. Wilting sometimes precedes reddening of the foliage, the most striking symptom, which occurs in late summer, fall, or early winter. Crowns

die from the tips down and from the inside out and often contain

secondary insects—bark beetles and wood borers. Young trees are

in the soil. Cedars and hemlocks are particularly susceptible.

Conifers that are flooded for long periods are killed or die

shortly after the water recedes. The foliage turns red and drops

off. When water is above the root collar, a "water line'' is left on

the tree.

Nutrition

Deficient or excess nutrients can cause symptoms similar to

sapsucking insect damage. Deficiencies generally aifect the foliage

most. Needles become chlorotic, turning pale or yellow at the tips

92
or along the sides, depending on the specific deficiency (plate

15, D).

Overnutrition may cause abnormal, flattened growth called fasciations (plate 31, Z)), or overabundant cones or shoots in certain

parts of the tree. Certain types of witches'-broom (plate 44, A)

may be due to overnutrition. These problems are localized and not

detrimental to the tree.

Mechanical

Few trees attain maturity without some mechanical damage.

Falling trees and branches injure standing trees; logging equipment breaks branches and gashes bark, causing wounds that provide excellent entries for diseases and secondary insects before

they heal. The weight of ice and snow may break the branches and

leaders of conifers; small trees and the lower branches of large

trees suffer most from this. Branches tend to be torn out (plate

35, C), and so differ from drooping branches caused by insects

such as the Zimmerman pine moth and eastern pineshoot borer

(plate 35, A and B). Hail causes defoliation, debarking, branch

breakage, and tree wounding, and even kills very young trees, so

at first glance hail-injured trees appear to be insect injured. Look

for scars or damage to the branches and stem on one side of

the tree.

93

PLATES

95
PLATE 1.—Conifers.

A, Red pine.

B. Eastern white pine.

C. Jack pine.

D. Scotch pine.

96
PLATE 1

97
PLATE 2.—Conifers.

A, White spruce.

B, Blue spruce.

C, Balsam fir.

D, Tamarack.

98
PLATE 2

99
PLATE 3.—Conifers.

100

A, Eastern hemlock.

B, Canadian yew.

C. Northern white-cedar (arborvitae).

D, Eastern redcedar (juniper).
PLATE 3

101
PLATE 4.—Foliage injury without webbing.

A. Partial and complete defoliation of both old and new needles on hemlock

branches caused by the hemlock looper (p. 27) ; for similar injury on hosts

other than hemlock, see webless moths (p. 26), grasshoppers and walkingstick (p. 25), or sawflies (p. 9) ; insect is usually needed for identification,

but see plates 4, 5, 6, and 7, for specific feeding patterns.

(NOTE: If needles have simply fallen off tree, see plate 12, A, B, and C).

B. Part or all of previous yearns needles (arrow) missing from branches,

especially pine; injury caused by spring-feeding sawflies (p. 9); larva

is needed for identification (see figs. 1, 2, and 3) ; if feeding is fresh, new

needles will be incompletely developed and needle fascicles in defoliated

zone may be still attached to branch (plate 5, B).

C Part or all of new and/or old foliage (arrows) missing from branches

of pine; injury caused by summer-feeding sawflies, most likely the redheaded pine sawfly (p. 16) ; larva is needed for identification (see figs.

1,2, and 3).

D. Mined leaves (arow) caused by arborvitae leafminer (p. 36) ; for related

miners on other conifers, see plates 7, 9, and p. 33.

102
PLATE 4

103
PLATE 5.—Foliage injury without webbing.

A, Tuft of skeletonized needles (arrow) on pine caused by young colonial

sawflies (p. 9); the tuft is brown and readily seen against green foliage;

note young larvae feeding below tuft.

B, Defoliation from colonial sawflies on pine (p. 9) ; notice the larval

colony and intact needle fascicles (arrow).

C, Tuft of partially eaten needles (arrow) on pine, characteristic of feeding

by the red pine sawfly (p. 21).

D, Isolated needle (arrow) on defoliated pine shoot, characteristic of feeding by Abbott's sawfly (p. 20).

104
PLATE 5

\ï mm

B

105
PLATE 6.—Foliage injury without webbing.

A, Drooping needles (arrow) on pine shoot; injury caused by either the

pine chafer (p. 24), ''needle blight" midge (p. 51), needle droop (p. 86),

or pine needle sheathminer (p. 34) ; see pages indicated for specific

identifiers.

B. Notched needles (arrows) on yew (also occasionally on hemlock, arborvitae, or spruce) ; injury caused by either black vine weevil (p. 66) or

strawberry root weevil (p. 66).

C. Irregular defoliation on pine caused by the pine tussock moth (p. 27) ;

the injury resembles feeding from solitary sawflies(p. 9) and walkingstick (rare) (p. 26) ; distinctive hairy cocoon (upper arrow) and larva

(lower arrow) identify the moth.

D, Tuft of clipped new needles (arrow) on pine caused by grasshopper

nibbling (p. 25).

106
107
PLATE 7.—Foliage injury without webbing.

A. Notched old needles on pine (occasionally hemlock or spruce) caused

by the pine chrysomelid (p. 25) ; male cones may be injured also (also see

plate 7,^).

B. New needles missing (arrow) on pine (occasionally hemlock or spruce),

caused by the pine chrysomelid (p. 25) (also see plate 7, A).

C Mined needles of pine caused by the pine needle miner (p. 34) ; other

pine needle miners are distinguishable by the injury they cause (p. 35).

D. Irregular defoliation caused by solitary or semicolonial sawflies (p. 9) ;

the injury resembles that of the pine tussock moth on pine (plate 6, C) and

walkingstick (rare) (p. 26).

108
PLATE 7

109
PLATE 8.—Foliage injury with webbing.

A. Webbed foliage of balsam fir (similar on spruce) caused by the spruce

budworm (p. 31) ; the injury is similar to that of the eastern blackheaded

budworm (p. 32) ; the larva (arrow) is distinctive; also look for distinctive

signs such as debris, frass, pupal cases after June.

B, Webbed foliage of pine caused by the jack pine budworm (p. 32) ; look

for debris, frass, and pupal cases (arrow) after June; larva is similar to

that of spruce budworm (plate 8, A).

C. Webbed foliage (arrow) and shoots of pine caused by the tip moth

Tortrix pallorana (p. 33) ; after shoots are tunneled, they wilt and droop,

resembling those in plate 30, A, but webbing is present.

D, Webbed and mined terminal needles of pine caused by the pine needle

sheathminer (p. 34); small hole (arrow) occurs near base of each mined

needle; mined needles later droop from the base resembling injury by

several other agents (see plate 6, A).

110
PLATE 8

111
PLATE 9.—Foliage injury with webbing.

A. Webbed and mined foliage on juniper caused by the young larvae of the

juniper webworm (p. 29) ; older larvae produce large and distinct nests

(see plate 11, A) ; a juniper needleminer (p. 36) and a hemlock needleminer

(p. 36) cause similar injury.

B. Webbed and mined foliage on spruce caused by the spruce needleminer

(p. 34) ; other spruce miners cause similar injury; see p. 33 and 34 for

characteristics.

C. Webbed and mined foliage on spruce caused by the spruce leafminer

(p. 33) ; other spruce miners cause similar injury; see p. 33 and 34 for

characteristics; also see spruce budworm (p. 31), especially if feeding

is on the shoot tips.

D. Webbed foliage on spruce caused by the spruce spider mite (p. 52) ;

foliage may be discolored but needles are not mined out.

112
113
PLATE 10.—Foliage injury and webbed concealments.

A. Cases Vé inch long (arrow) on defoliated larch branch, constructed by

the larch casebearer (p. 35).

B. Bags 1 inch long (arrow) on defoliated arborvitae (also may be on

other conifers) constructed by the bagworm (p. 29).

C. Tubes 1 inch long (arrow) on eastern white pine, constructed by the

pine tube moth (p. 29) ; a pine needleminer makes a similar tubed concealment on jack and ponderosa pine (p. 35).

D. Small nest % inch long (arrow) on red pine shoot, constructed by the

pine webworm (p. 30) ; certain coneworms (Dioryctria spp., p. 82) and

nesting pine sawflies (p. 30) construct similar small nests.

114
PLATE 10

115
PLATE 11.—Foliage injury and webbed concealments.

A. Nests on juniper constructed by the juniper webworm (arrow) (p. 29)

also see plate 9, A, for small nest and plate 11, B, for larvae.

B, Nest of the juniper webworm opened to show larvae.

C. Nest on pine constructed by the pine false webworm (p. 30) ; larvae

or cast skins are needed to distinguish this species from the nesting pine

sawfly (p. 30) and the pine webworm (p. 30).

D. Nest on pine constructed by the pine webworm (p. 30) ; larvae or cast

skins are needed to distinguish this species from the pine false webworm

(p. 30) and the nesting pine sawfly (p. 30).

116
PLATE 11

117
PLATE 12.—Foliage discolored.

A. Upper crown or entire tree (or seedling) uniformly yellow, red, or brown;

this symptom can be caused by many tree-killing agents; examine the tree

closely for signs of the insect or injury (see p. 2 for instructions).

B. Shoot tips or branches flagging—yellow, red, or brown; this symptom can

be caused by several agents; examine the tree closely for signs of the insect

or injury (see p. 2 for instructions).

C. Lower crown (arrow) discolored (or bare because of needle fall) caused

by brown spot disease (p. 85) ; also see other needlecast diseases, p. 85

and 86.

D. Foliage on shoots or branches blackened (arrow) by a sooty mold fungus

(p. 85) ; this fungus indicates the presence or recent occupancy of aphids

(p. 44), soft scales (p. 41), or spittlebugs (p. 37).

118
PLATE 12

119
PLATE 13.—Foliage discolored.

A. Flagged shoot tips (arrow) of juniper caused by the juniper tip midge

(p. 51).

B. Pale, thin foliage on pine caused^by the black pineleaf scale (p. 42) (also

see plate 17, A and B, of the scale).

C. Flagged shoot tips on pine caused by the gouty pitch midge (p. 50) (also

see plate 39, C and D, for specific identifiers).

D. Flagged shoot tips on yew caused by black vine weevil larvae feeding on

roots (p. Ç>Q) \ similar injury is caused by the strawberry root weevil (p.

120
PLATE 13

121
PLATE 14.—Foliage malformed.

A. Curled needle tips (arrow) of pine caused by eriophyid mites (p. 53) ;

needle tips are usually discolored; a hand lens is needed to detect the mites

on the needles in the fascicle region (also see plate 14, B),

B. Eriophyid mites on pine needles, highly magnified (p. 53).

C. Curled needles (arow) of pine caused by pine thrips (p. 49) ; look for

brownish wounds on the needles, as in plate 14, D,

D, Wound on pine needle (arrow) and adult pine thrips, highly magnified

(p. 49) ; immature thrips are yellow.

122
PLATE 14

123
PLATE 15.—Foliage spotted or discolored.

A, B. Red pine infected with pustules of the red pine needle rust (a disease) ;

similar rusts occur on other conifers (p. 85) ; these may resemble scale

insects at first glance.

C. Jack pine infected with needlecast (a disease), showing hysterothecia

(arrow) (p. 85).

D. Spruce showing symptoms of a nutrient deficiency (arrow) ; symptoms

vary somewhat depending on the nutrient involved (p. 92).

124
PLATE 15

125
PLATE 16.—Foliage spotted.

A, B, Egg cluster of a colonial sawfly (p. 9) ; these eggs superficially resemble scale insects but are in the needles rather than on them.

C, D, Pine needle scale on needles of pine (also found on other conifers) (p.

42).

126
PLATE 16

127
PLATE 17.—Scales and aphids.

Af B. Black pineleaf scales (arrow) on pine needles (p. 42).

C, D. Eastern spruce gall aphid adults (arrow) on spruce needles; migrant

adults of other species of gall aphids are similar (p. 46).

128
PLATE 17

129
PLATE 18.—Scales and aphids.

A. Fletcher scale (arrow) on arborvitae foliage (p. 42) (also see plate 1S,B),

B. Fletcher scale on juniper shoot (p. 42) (also see plate 18, A).

C. Cooley spruce gall aphid on Douglas-fir needles (p. 47) ; the alternate

generation of this aphid makes a gall on spruce (see plate 23, B),

D. Juniper scale (arrow) on juniper foliage (p. 42).

130
PLATE 18

131
PLATE 19.—Scales and scalelike fruit.

A, Female pine tortoise scales (arrow) on pine shoot (p. 41).

B. Male pine tortoise scales on pine shoot (p. 41).

C. Spruce bud scales on spruce shoot (p. 43) ; observe carefully to distinguish

them from true buds.

D, Juniperberries on juniper; although these are the fruit of juniper, they

are occasionally mistaken for scales (p. 41) or disease galls (p. 87).

132
PLATE 19

133
PLATE 20.—Woolly aphids and scales.

A. Eastern spruce gall aphid egg cases on spruce (p. 46).

B. Woolly pine scale on red pine (p. 43).

C. Possible Pulvinaria sp. (arrow) on balsam fir (p. 43).

D. Woolly larch aphids on larch (p. 47).

134
PLATE 20

135
PLATE 21.—Aphids.

A. Pine bark aphids on pine twig (p. 44).

B, Aphid egg clusters on pine needles (p. 44).

C. Woolly larch aphid colonies (arrow) clustered at base of larch shoots (p.

47).

D. Typical colony of naked aphids (or plant lice) (p. 44) on conifer twig.

136
PLATE 21

137
PLATE 22.—Frothy concealments.

A. Spittlemass on pine constructed by the pine spittlebug (p. 39), which

resembles the rarer Clastoptera spittlemasses on pine and juniper (p. 40)

(also see plate 22, B),

B. Spittlemass of pine spittlebug opened to show the nymph (arrow).

C. Spittlemass at base of herbaceous vegetation (in a pine stand) constructed

by the Saratoga spittlebug (p. 37), resembling the less common spittlemass

of the Signoret spittlebug (p. 40) (also see plate 22, D),

D. Spittlemass of the Saratoga spittlebug opened to show the nymph.

138
PLATE 22

139
PLATE 23.—Galls.

A. Galls on spruce (arrow) of eastern spruce gall aphid (p. 46).

B, Gall on spruce of Cooley spruce gall aphid (p. 47) ; the alternate generation aphids occur on Douglas-fir (see plate 18, C).

C Gall on spruce (arrow) of the red spruce aphid (p. 48) ; the alternate

generation aphids occur on eastern white pine.

D, Gall on spruce (arrow) of the woolly larch aphid (p. 47) ; the alternate

generation aphids occur on larch (see plate 21, C).

140
PLATE 23

141
PLATE 24.—Galls.

A, Gall on spruce (arrow) of spruce gall aphid (p. 48).

B, Gall on spruce, aphid unknown (p. 48).

C. Gall on spruce (arrow), aphid unknown (p. 48).

D. Gall on spruce, aphid unknown (p. 48).

142
PLATE 24

143
PLATE 25.—Galls.

A. Curled needles (arrow) of balsam fir resembling a gall caused by the

feeding of an unknown aphid (p. 48).

B, Gall on spruce (arrow), aphid unknown (p. 48).

C. Gall on spruce (arrow), aphid unknown (p. 48).

Z). Old, opened gall on spruce, aphid unknown (p. 48).

144
PLATE 25

145
PLATE 26.—Galls.

A. Gall on white spruce caused by spruce gall midge (p. 51) (see plate 26, B),

B. Gall of spruce gall midge, opened to show maggots (arrow).

C. Gall on balsam fir needles caused by balsam gall midge (p. 50).

D. Gall on pine needle bases and maggots (arrow) of red pine needle midge

(p. 50); needles are discolored and abnormally shortened.

146
PLATE 26

147
PLATE 27.—Galls.

A, Gall on red pine shoot (arrow) caused by the pine gall weevil (p. 65)

(also see plate 27, B),

B. Gall of pine gall weevil with bark removed to show larval cells (p. 65)

(also see plate 27, A).

C. Gall on arborvitae (arrows) caused by bark beetles (p. 72).

D. Gall on pine seedlings caused by sweetfern rust, a disease (p. 88).

148
PLATE 27

149
PLATE 28.—Galls.

A, Gall on jack pine (also occurs on Austrian and Scotch) caused by eastern

gall rust, a disease (p. 87).

B, Gall on pine seedlings (arrow) caused by eastern gall rust, a disease (p.

87).

C. Gall on juniper (arrow) caused by cedar-apple rust, a disease (p. 87)

(also see plate 28, D).

D, Spore horns (orange) of cedar-apple rust on juniper, a disease (p. 87)

(also see plate 28, C).

150
PLATE 28

151
PLATE 29.—Bud injury.

A. Pine bud injured at side or base (arrow) by the European pine shoot moth

(p. 54) ; injury may include a pitch tent (see plate 38, D).

B. Pine bud injured by Rhyacionia adana (p. 54) producing stunted new

needles; a hole (arrow) is present at base of shoot; a few old needles may

be mined out nearby; the red pine cone beetle causes similar injury in

autumn prior to overwintering (p. 81).

C. Pine bud injured by the pine candle moth (p. 55) ; a small amount of loose

webbing and frass occurs at the base (arrow) ; male flowers may also be

attacked (see plate 30, C). (Note: If the bud is on jack pine, the injury is

caused by Petrova bud borers, p. 55).

D. Buds hollowed out by the spruce budworm (p. 31) or eastern blackheaded

budworm (p. 32) look like cups (arrow) on balsam fir (and spruce).

152
PLATE 29

153
PLATE 30.~-Shoot injury.

A, B. Drooping, stunted, and distorted terminals and laterals on pine, caused

by European pine shoot moth (p. 54) ; plate 30, B specimen opened to show

pupa in tunnel (arrow) ; other types of injury should be apparent also

(see plate 36).

C. Drooping, stunted new shoot (arrow) on pine caused by pine candle moth

(p. 55) (also see plate 29,C) ; larval tunnel is in the old growth tissues

below the injury.

D. Wilted new shoots (arrow) of conifer caused by frost (p. 91) ; wilted

shoots should occur on all or most of the tree.

154
PLATE 30

155
PLATE 31.—Shoot injury.

A. Early shoot curl of larch caused by eggs (arrow) of the larch sawfly (p.

23) (also see plate 31, B).

B, Shoot curl (pig-tail) of larch indicating egg site of the larch sawfly (p.

23) (also see plate 31, A).

C. Stunted shoot with stunted discolored needles caused by aphids (p. 44).

D. Distorted flattened shoots (fasciation) caused by abnormal nutrition (p.

92).

156
PLATE 31

B

157
PLATE 32.—Shoot injury.

A, B. Wilted terminal and lateral shoots (shepherd's crooks) of pine caused

by the white pine weevil (p. 59) ; bark on the stem below the wilted area

will have small pin holes that exude droplets of pitch (see plate 50, A) ;

remove the bark to find larval galleries and pupal cells (see plate 33, A).

C. Wilted terminal shoot of spruce caused by the white pine weevil (p. 59).

Remove the bark to find larval galleries and pupal cells (see plate 33, A),

D. Dead terminal and upper crown (spike top) caused by any of several

agents; look for more specific types of injury (see p. 2 if foliage is discolored, or p. 3 if foliage is missing.

158
PLATE 32

159
PLATE 33.—Shoot injury.

A. Galleries and pupal cells (arrow) in pine leader (bark removed) made by

the white pine weevil (p. 59) (also see plates 32, A, B, and C, and 40, A),

B. Feeding- puncture scars on the wood of a pine shoot (bark removed) made

by Saratoga spittlebug (p. 37) ; similar scars are also made by the pine

spittlebug, but on the inner surface of the bark (note two normal shoots

for comparison).

C. Discolored, stunted pine shoot (arrow) ; injury caused by one of several

possible agents; look for the insect, signs of other agents, or more definitive injury in other photos; cut shoot open and remove bark for other

signs (see p. 2).

D. Hollowed-out pine shoot made by one of several possible agents; look for

the insect, signs of other specific agents, or more definitive injury in other

photos (see p. 2).

160
PLATE 33

161
PLATE 34.—Shoot injury.

A. Holes in current-year shoots (arrow) of pine, caused by feeding of adult

Magdalis perforatis (p. 66) ; shoot may be stunted and needles shortened.

B. Holes in previous-year shoots and branches of pine, caused by feeding of

adult Pissodes weevils (p. 59) ; holes may have small pitch exudations, as

in plate 40, A.

C. Exit hole (Va to ^/4 inch) of eastern pineshoot borer (p. 54) on flagged or

broken pine shoot (also see plate 35, A).

D. Ragged hole in bark on shoot or branch of pine caused by adult Hylobius

weevils (p. 59) ; if needles have obviously been chewed off, too, the injury

is from sawfly larvae (p. 9); injury resembles sawyer beetle injury (plate

47, D).

162
PLATE 34

163
PLATE 35.—Branch injury.

A. Broken terminal or lateral shoots on pine, caused by eastern pineshoot

borer (p. 54). Look for an exit hole (plate 34,C) on lower flagged portion

of shoot.

B. Broken terminal or lateral shoot on pine, caused by Zimmerman pine moth

(p. 56). Broken area has a whitish or pinkish pitch exúdate. (Also see

plates 40, C, 40, D, 41, A, 42, A).

C. Broken branches caused by heavy snow or ice accumulation. Base of

branch is torn from stem (p. 93).

D, Wound near shoot tip (arrow) caused by small mammals (p. 90) or man

(p. 90) removing cones. Bark tissues are torn.

164
PLATE 35

165
PLATE 36.—Branch injury.

Posthorn, forks, and bushiness caused by European pine shoot moth (p. 54)

(also see plate 42, D) ; similar injuries can be caused by other agents that

injure terminal shoots or buds.

166
PLATE 36

167
PLATE 37.—Pitch exudates (tubes).

A. Pitch tube (arrow) on pine shoot tip, caused by the jack pine tip beetle

(p. 72) ; shoot tip above the pitch tube flags (also see plate 37, B).

B. Pitch tube (arrow) on pine shoot, caused by jack pine tip beetle (p. 72) ;

new shoot above pitch tube wilts and flags (similar wilting injury is caused

by Cecidmyia banksianae, a midge, p. 49).

C. Pitch tubes on conifer bole, caused by bark beetles (p. 67) (see closeup

plate 37,0). ^

D, Pitch tube on bark (closeup), caused by bark beetle (p. 67), showing

entrance hole.

168
PLATE 37

169
PLATE 38.—Pitch exudates (blisters).

A, B, Pitch blister on pine constructed by the northern pitch twig moth (p.

57) ; the hollow blister is found in the crotch of pine twigs and houses the

larva.

C. Pitch blister on pine shoot constructed by a pitch blister moth (p. 58) ;

the blister is thick walled and not in a twig crotch.

D, Pitch "tent'' (arrow) at base of pine bud, constructed by the European

pine shoot moth (p. 54).

170
PLATE 38

171
PLATE 39.—Pitch exudates.

A. Pitch exúdate on jack pine shoot, caused by a pine pitch midge (p. 49) ;

shoot tip usually flags above exúdate (also see plate 39, B),

B. Pitch exúdate (closeup) of a pine pitch midge (p. 49) ; yellow-orange

maggots (arrow) in the pitch are usually visible to the naked eye.

C. Pitch exudates (arrow) on jack pine shoot, caused by the gouty pitch

midge (p. 50) (also see plate 39, D).

D. Maggots of gouty pitch midge (arrows) in cells (p. 50), shoot cut open.

172
PLATE 39

173
PLATE 40.—Pitch exúdales.

A. Pitch exudates (arrow) on terminal of conifer, caused by white pine

weevil feeding (p. 59) ; exudates are similar for lodgepole terminal weevil

(p. 60) ; aphids may cause similar exudates on shoots, but feeding punctures are almost invisible (p. 44).

B. Pitch exudates on conifer twig or stem, caused by pales weevil feeding

(p. 64); feeding scars are larger than those for Pissodes weevils( see

plate 40, A).

C. Pitch exúdate (arrow) at base of pine branch caused by Zimmerman pine

moth (p. 56) ; branch usually breaks and flags (also see other kinds of

injury from this insect, plates 40, D; 35, B; 42, A; and 41, A).

D. Pitch tube (arrow) near center of pine shoot caused by Zimmerman pine

moth (p. 56) ; it is larger than the pitch tubes of the jack pine tip beetle

(plate 37, A and^).

174
PLATE 40

175
PLATE 41.—Pitch exudates.

A. Amorphous pitch mass (up to 3 inches diameter) on pine bole, caused by

Zimmerman pine moth (p. 56) ; the pitch mass is usually at the node and

is especially associated with pruning or bark wounds.

B. Amorphous pitch mass (up to 4 inches diameter) on pine bole, caused by

pitch mass borer (p. 57) ; pitch mass is commonly associated with injuries

or pruning wounds.

C. Ovoid or spherical pitch mass (up to 2 inches diameter) on red or jack

pine bole, caused by the pitch mass beetle (p. 57) (also see plate 41, D),

D. Larva of pitch mass beetle in cell (pitch mass removed). (See also plate

41, C).

176
PLATE 41

177
PLATE 42.—Stem injury.

A. Swollen node of pine caused by Zimmerman pine moth (p. 56) ; injury

usually results in a pitch exúdate (arrow).

B. Vertical trunk scars (arrow) caused by sweetfern rust (p. 88) ; lightening causes similar injury (p. 93).

C. Branch fork, caused by one of several possible agents that killed the terminal; it is difficult to determine the cause of a fork this old (see p. 3).

D. Old Posthorns caused by the European pine shoot moth (p. 54) ; such

deformities tend to disappear as the stem grows in diameter.

178
PLATE 42

179
PLATE 43.—Stem injury.

A. Pine bark aphids on stem of pine (p. 44) (also see plate 21, A).

B. Fir broom rust, a disease, on stem of balsam fir (p. 88) ; note swelling

and associated witches'-broom (arrow).

C. Canker of white pine blister rust, a disease, on eastern white pine (p. 87).

D. Canker of comandra blister rust, a disease, on jack pine (and Austrian

and Scotch pine) (p. 87).

180
PLATE 43

181
PLATE 44.—Stem injury.

A. Witches^-broom caused by rust fungi, a disease (p. 87).

B. Mushrooms at base of conifer indicating Armillaria root rot, a disease

(p. 89) ; remove bark at ground line to observe white fans of mycelia.

C. Mushroom (conk) at base of conifer, indicating Fomes sp. and related

root rots, a disease (p. 88).

D. Abnormal growth on conifer stem, cause unknown (p. 86).

182
PLATE 44

183
PLATE 45.—Stem injury.

A. Bark missing from stem near base of conifer (arrow) ; injury caused by

rodents or rabbits (p. 90) ; look for toothmarks or clean-cut tissues.

B. Bark missing from upper part of stem (arrow) ; injury caused by porcupines (p. 90) ; look for toothmarks or clean-cut tissues.

C. Bark missing from one side of stem; injury caused by deer scraping

antlers (buck rub) against bark (p. 90) ; bark is torn or shredded; similar

injury is caused by bears (p. 90), mechanical devices, or vehicles (p. 90).

D. Dead and discolored wood (arrow) on stem or branch of pine (bark

removed), caused by Scleroderris canker (p. 86); tree may be flagged or

off color (plate 12, A and B).

184
PLATE 45

185
PLATE 46.—Stem injury.

A,B. Holes in bark (Vs to VÍ inch in diameter), often arranged in rows or

columns, caused by sapsucker (birds) feeding (p. 89).

C. Large conical hole in bark {V2 to 1 inch in diameter) caused by woodpecker feeding (p. 89) ; the hole is found in weakened or dead trees infested

with bark beetles or wood borers.

D. Holes in bark (1/16 inch diameter) extending into the wood, caused by

adult bark beetles (p. 67) ; remove bark to see if there are galleries as in

plate 52, A or figure 18, to confirm that damage is by bark beetles.

186
187
PLATE 47.-~Root and bark injury.

A. Bark missing (arrow) from seedling, caused by pales weevil (p. 64) ;

this injury is associated with weevil-infested stumps nearby (see plate

49, C).

B. Root bark (arrow) and rootlets missing from yew (also hemlock or other

conifers), caused by adult black vine weevil (p. 66), or adult strawberry

root weevil (p. 66); seedlings are discolored or dead; adult weevils are

needed for positive identification.

C. Rootlets missing (arrow) from seedlings, caused by white grubs (p. 78) ;

seedlings usually are discolored or dead.

D. Bark missing from twigs and small branches caused by adult sawyer

beetles (roundheaded borers (p. 74) ; shoot tips are usually flagged,

especially on eastern white pine or balsam fir; injury resembles weevil

injury (plate 34, Z)).

188
PLATE 47

189
PLATE 48.—Root collar injury.

A. Root collar of pine riddled with g:alleries; soil surrounding the stem is

infiltrated and blackened with pitch; injury caused by pine root collar

weevil (p. 62).

B. Leaning or fallen pine, broken over at root collar, caused by damage

from pine root collar weevil (p. 62) (also see plate 48, A).

C. Root collar of pine riddled with galleries and with hardened irregular

pitch tubes (arrow) at collar; injury caused by Warren's collar weevil

(p. 64).

D. Root tips severed (right arrow) and roots hollowed out on pine, associated with pitch exúdate (left arrow) ; injury caused by root tip weevil

(p. 63) ; tree may have flagged branches (plate 12, B).

190
PLATE 48

191
PLATE 49.—Wood injury.

A. Galleries on wood surface (arrow) and tunnels of roundheaded wood

borers (p. 74) (also see plate 49, B).

B. Tunnels of roundheaded wood borers in wood tissues (p. 74) (also see

plate 49, A).

C. Chip cocoons (arrow) of northern pine weevil (p. 61); similar cocoons

are constructed by other Pissodes and Hylobius weevils (p. 58), but location

differs for most.

D. Gallery (arrow) of Hylobius congener in bark (p. 64) ; gallery of Pissodes rotundatus in spruce is similar (p. 62).

192
PLATE 49

193
PLATE 50.—Wood injury.

A. Galleries of hemlock borer (p. 74) ; other flatheaded borers (p. 73) make

similar galleries.

B. Galleries of Pissodes affinis in pine (p. 62).

C. Galleries of wood wasps (horntails) (p. 76) ; frass is usually packed

tightly in the galleries.

D. Pin holes (1/16 to Vs inch diameter) of powder-post beetles in seasoned

wood (p. 77) ; fine, powdery, boring dust accumulates in and below the

holes.

194
PLATE 50

i.. ,' ?. I. ' .t195
PLATE 51.—Wood injury.

A. Wood honeycombed by termites (p. 78) ; a whitish substance coats the

wood; the galleries often contain soil and debris; the whitish insects are

the termites.

B. Wood honeycombed by carpenter ants (p. 77) ; the galleries are kept

clear of debris.

C. Heartwood decayed by heart rot fungi, a disease (p. 88) ; the wood is

soft and punky.

D. Sawdustlike debris (arrow) indicates wood borers are feeding beneath

bark; beetles can be distinguished by the coarseness of debris beneath the

bark as follows: powder-post beetles, fine dust (p. 77) ; bark beetles, coarse

dust (p. 67) ; flatheaded borers, coarse slivers (p. 73) ; and roundheaded

borers, very coarse slivers, loosely packed (p. 74).

196
PLATE 51

197
PLATE 52.--Wood injury.

A. Galleries of pine engraver (p. 70) (see fig. 18 for galleries of other

bark beetles).

B. Galleries and cells of red turpentine bark beetle containing larvae, pupae,

and adult beetles (p. 69).

C. Pupal chamber of Acanthocinus in spruce (p. 76).

D. Root collar region (cross section) of pine stem killed by pine root collar

weevil (p. 62).

198
PLATE 52

199
PLATE 53.—Cone injury.

A. Uninjured male flower (cone) of pine; several insects feed inside the male

cones of conifers (see budworms, p. 30).

B, Douglas-fir cone injured by the spruce coneworm (p. 83) ; note excrement

on cone (arrow) ; for other spruce cone insects see p. 83.

C White pine cones injured by the white pine cone beetle (p. 81); note

gallery in central axis (arrow).

D, Red pine cones injured by the red pine cone beetle (p. 81); injured cones

(upper) are soft, stunted, and brown; lower cone is normal (see also

plate 54, A ).

200
PLATE 53

201
PLATE 54.—Cone injury (red pine).

A. Conophthorus resinosae injury showing basal groove (also see plate 53,

i),p.81).

B. Eucosma monitorana injury showing exit holes between scales (arrow)

(p. 82) ; if spruce, see Pegohylemia (p. 84).

C. Eucosma monitorana injury (internal) (p. 82).

D. Dioryctria abietella injury showing frass in webbing (p. 83).

E. Dioryctria disclusa injury showing basal hole (arrow) (p. 82).

F. Dioryctria disclusa injury (internal) (p. 82).

G. Laspeyresia toreuta injury (internal) ; cones appear normal externally

p. 82).

H. Rabsaamenia sp. injury showing pitch globule (arrow) (p. 84).

/. Rabsaamenia sp. injury (internal) (p. 84).

202
PLATE 54

203
PLATE PHOTO CREDITS

Platel: (A) F-521438, (B) F-521437, (C) F-521440, (D) F-521439.

Plate 2: (A) F-521441, (B) F-521442, (C) F-521444, (D) F-521443.

Plate 3: (A) F-521446, (B) F-521445, (C) F-521448, (D) F-521447.

Plate 4: (A) Photo courtesy of the Ontario Region, Department of Fisheries

and Forestry, negative number 2167, (B) F-521511, (C) F-521510, (D)

Photo courtesy of Michigan State University, negative number 703116-1.

Plate 5: (A) F-508527, (B) F-508529, (C) F-521501, (D) F-521500.

Plate 6: (A) F-521504, (B) F-521503, (C) F-521502, (D) F-516559.

Plate 7: (A) Photo courtesy of the University of Wisconsin, negative number

32195-C-l, (B) Photo courtesy of the University of Wisconsin, negative

number 32192-C-l, (C) Photo courtesy of Michigan State University, negative number 702730, (D) F-519844.

Plate 8: (A) F-501800, (B) Photo courtesy of Michigan State University,

(C) Photo courtesy of Michigan State University, negative number 5728,

(D) F-498343.

Plate 9: (A) F-521499, (B) Photo courtesy of Michigan State University,

negative number 4783, (C) Photo courtesy of Michigan State University,

negative number 4063, (D) Photo courtesy of the Canadian Forest Service.

Plate 10: (A) F-509463, (B) F-521497, (C) F-521496, (D) F-521498.

Plate 11: (A) Photo courtesy of the Illinois Natural History Survey, negative

number 161789, (B) Photo courtesy of Michigan State University, negative

number 3496, (D) Photo courtesy of the Connecticut Agricultural Experiment

Station.

Plate 12: (A) Photo courtesy of the Michigan Department of Agriculture,

(B) F-521494, (C) Photo courtesy of Michigan State University, negative

number 70968-2, (D) F-521495.

Plate 13: (A) Photo courtesy of the Ohio Agricultural Research and Development Center, (B) F-506705, (C) F-493083, (D) Photo courtesy of the Ohio

Agricultural Research and Development Center.

Plate 14: (A) F-521493, (B) Photo courtesy of Michigan State University,

negative number 7153-1, (C) Photo courtesy of Michigan State University,

negative number 71746, (D) Photo courtesy of Michigan State University.

Píatelo: (A) F-521508, (B) F-521509, (C) F-521492, (D) F-521491.

Plate 16: (A) F-501798, (B) F-521489, (C) F-521490, (D) F-501802.

Plate 17: (A) F-506704, (B) F 506706, (C) Photo courtesy of Michigan State

University, negative number 4879, (D) Photo courtesy of Michigan State

University, negative number 4878.

Plate 18: (A) Photo courtesy of Michigan State University, negative number

4904a, (B) Photo courtesy of Michigan State University, (C) Photo courtesy

of Michigan State University, (D) Photo courtesy of Michigan State University, negative number 5184.

Plate 19: (A) Photo courtesy of Michigan State University, negative number

4906, (B) Photo courtesy of Michigan State University, negative number

204
3082, (C) Photo courtesy of Michigan State University, negative number

3084, (D) Photo courtesy of Michigan State University, negative number

4661.

Plate 20: (A) Photo courtesy of Michigan State University, negative number

3752, (B) Photo courtesy of Michigan State University, negative number

4005, (C) Photo courtesy of Michigan State University, (D) Photo courtesy

of Michigan State University, negative number 5331.

Plate 21: (A) Photo courtesy of Michigan State University, negative number

3405, (B) F-521488, (C) Photo courtesy of Michigan State University,

negative number 1094, (D) F-521487.

Plate 22: (A) F-521484, (B) F-521485, (C) F-489365, (D) F-521486.

Plate 23: (A) Photo courtesy of Michigan State University, (B) Photo

courtesy of Michigan State University, negative number 17922-7, (C) Photo

courtesy of Michigan State University, (D) Photo courtesy of Michigan State

University, negative number 5185.

Plate 24: (A) Photo courtesy of Michigan State University, negative number

4740, (B) Photo courtesy of Michigan State University, negative number

4743, (C) Photo courtesy of Michigan State University, negative number

4844, (D) Photo courtesy of Michigan State University, negative number

4914a.

Plate 25: (A) Photo courtesy of Michigan State University, negative number

6014, (B) Photo courtesy of Michigan State University, (C) Photo courtesy

of Michigan State University, negative number 5186, (D) Photo courtesy

of Michigan State University, negative number 4847.

Plate 26: (A) F-501806, (B) F-521482, (C) F-521483, (D) Photo courtesy

of the University of Wisconsin.

Plate 27: (A) F-521480, (B) F-521481, (C) Photo courtesy of Michigan

State University, negative number 6315, (D) F-502134.

Plate 28: (A) F-501562, (B) F-501561, (C) F-521479, (D) Photo courtesy

of Michigan State University.

Plate 29: (A) Photo courtesy of Michigan State University, negative number

17886-3, (B) Photo courtesy of the Michigan Department of Natural Resources, (C) F-521478, (D) F-494389.

Plate 30: (A) F-492261, (B) F-501807, (C) F-421477, (D) Photo courtesy

of Michigan State University.

Plate 31: (A) F-485947, (B) Photo courtesy of the Canadian Forestry Service, negative number 3258, (C) Photo courtesy of Michigan State University,

(D) F-523430.

Plate 32: (A) F-500834, (B) F-480420, (C) Photo courtesy of Michigan

State University, negative number 67722, (D) F-521476.

Plate 33: (A) Photo courtesy of Michigan State University, negative number

4034, (B) F-501804, (C) F-521475, (D) F-521469.

Plate 34: (A) Photo courtesy of the Canadian Forestry Service, negative

number 3247, (B) Photo courtesy of the Canadian Forestry Service, negative

number 3246, (C) Photo courtesy of Michigan State University, (D) Photo

courtesy of the Canadian Forestry Service, negative number 3322.

205
Plate 35: (A) F-492898, (B) F-521470, (C) F-521467, (D) F-521468.

Plate 36: (A) F-490260, (B) F-521471, (C) F-521473, (D) F-521472.

Plate 37: (A) F-519677, (B) Photo courtesy of Michigan State University,

negative number 707730-2, (C) F-494420, (D) Photo courtesy of Michigan

State University, negative number 692605-1.

Plate 38: (A) F-521465, (B) F-521466, (C) Photo courtesy of Michigan

State University, negative number 7090, (D) Photo courtesy of the Ohio

Agricultural Experiment Station.

Plate 39: (A) Photo courtesy of Michigan State University, negative number

4037, (B) F-521462, (C) F-493085-A, (D) F-493085-B.

Plate 40: (A) Photo courtesy of Michigan State University, negative number

63800-2, (B) F-314142, (C) F-492959, (D) F-521464.

Plate 41: (A) F-492960, (B) F-521463, (C) F-518186, (D) F-518188.

Plate 42: (A) Photo courtesy of Michigan State University, (B) F-502130,

(C) F-493926, (D) F-490253.

Plate 43: (A) F-692605, (B) F-504409, (C) F-487420, (D) Photo courtesy

of Michigan State University, negative number 70968-5.

Plate 44: (A) F-521457, (B) F-514871, (C) F-501574, (D) Photo courtesy

of Michigan State University, negative number 5335.

Plate 45: (A) Photo courtesy of the Michigan Department of Agriculture,

(B) F-521460, (C) F-521461, (D) Photo courtesy of Michigan State University, negative number 70968-7.

Plate 46: (A) Photo courtesy of the Michigan Department of Agriculture,

(B) F-521505, (C) F-521459, (D) F-521458.

Plate 47: (A) F-514140, (B) Photo courtesy of Michigan State University,

negative number 4804, (C) F-494653, (D) Photo courtesy of Michigan State

University, negative number 6266.

Plate 48: (A) Photo courtesy of the Michigan Department of Natural Resources, (B) F-521454, (C) Photo courtesy of William Turnock, Canada,

(D) F-521455.

Plate 49: (A) F-496926, (B) Photo courtesy of Michigan State University,

(C) F-521453, (D) Photo courtesy of the Canadian Forestry Service.

Plate 50: (A) F-514869, (B) Photo courtesy of the Canadian Forestry Service, (C) F-521452, (D) F-521451.

Plate 51: (A) F-494578, (B) Photo courtesy of Michigan State University,

negative number 5013, (C) F-508004, (D) F-501809.

Plate 52: (A) F-501931, (B) F-494429, (C) Photo courtesy of Michigan

State University, negative number 6267, (D) F-521450.

Plate 53: (A) Photo courtesy of Michigan State University, negative number

70968-3, (B) Photo courtesy of Michigan State University, negative number

4315, (C) F-505549, (D) F-519679.

Plate 54: (A) F-506524, (B) F-506525, (C) F-506525, (D) F-506523, (E)

F-506522, (F) F-506522, (G) F-506527, (H) F-506526, (I) F-506526.

206
INDEX TO INSECTS BY HOST PLANTS

Arborvitae (see northern

white-cedar)

Page

Cedar, Eastern red (Juniper)

Borers, root

Pales weevil 64

Borers, shoot and stem

Northern cedar bark

beetle 71

Redcedar bark beetle 71

Leaf feeders

Bagworm 29

Imperial moth 27

Juniper webworm 29

Sucking insects

Fletcher scale 42

Juniper scale 42

Juniper tip midge 51

Red cedar aphid 46

Spruce spider mite 52

Tipwarf mite 53

Cedar, Northern white

(Arborvitae)

Borers, shoot and stem

Allegheny mound ant 78

Northern cedar bark

beetle 71

Redcedar bark beetle 71

Borers, wood

Black carpenter ant 77

Urocerus^sp. 76

Gall insects

"Gall beetle" 72

Leaf feeders

Bagworm 29

Eastern cedar sawfly 23

Strawberry root weevil _ &6

Leaf miners

Arborvitae leafminer 36

Root feeders

Strawberry root weevil _ 66

Sucking insects

Arborvitae aphid 45

Fletcher scale 42

Juniper scale 42

Spruce spider mite 52

Tipwarf mite 53

Page

Fir, Balsam—continued

Pales weevil 64

Warren's collar weevil 64

Borers, shoot and stem

Balsam fir bark beetle 72

Borers, wood

Black carpenter ant 77

Eastern subterranean

termite 78

Melanophila fulvoguttata 73

Monochamus marmorator 74

Monochamus notatus 74

Monochamus scutellatus _ 74

Cone insects

Fir coneworm 83

Spruce coneworm 83

Gall insects

Balsam bark weevil 62

Balsam gall midge 50

Leaf feeders

Balsam fir sawfly 21

Eastern blackheaded

budworm 32

Eastern hemlock looper _ 27

Pine tussock moth 27

Spruce budworm 31

Leaf miners

Pine needle sheathminer _ 84

Root feeders

White grubs 78

Sucking insects

Balsam twig aphid 45

Pine needle scale 42

Pine spittlebug 39

Pulvinaria scale 43

Signoret spittlebug 40

Spruce spider mite 52

Fir, Douglas

Borers, root

Pales weevil 64

Cone insects

Fir coneworm 83

Spruce coneworm 83

Leaf feeders

Spruce budworm 31

Sucking insects

Cooley spruce gall aphid _ 47

Fir, Balsam

Borers, root

Hemlock, Eastern

Borers, wood

207
Page

Hemlock, Eastern—continued

Melanophila fulvoguttata 73

Leaf feeders

Black vine weevil 66

Hemlock looper 27

Strawberry root weevil 66

Leaf miners

Pulicalvaria abietisella 34

Root feeders

Black vine weevil 66

Strawberry root weevil 66

Sucking insects

Hemlock scale 43

Pine needle scale 42

Pine spittlebug 39

Spruce spider mite 52

Juniper, Common

Borers, shoot and stem

Northern cedar bark

beetle 71

Redcedar bark beetle 71

Leaf feeders

Juniper webworm 29

Leaf miners

Phalonia rutilaría 36

Sucking insects

Fletcher scale 42

Juniper scale 42

Tipdwarf mite 53

Larch (see tamarack)

Pine, Austrian

Borers, root

Pine root collar weevil 62

Borers, shoot and stem

Eastern pineshoot borer _ 54

European pine shoot

moth 54

Northern pine weevil 61

Pine candle moth 55

Pitch mass borer 57

Zimmerman pine moth 56

Leaf feeders

Abbott's sawfly 20

European pine sawfly 21

Pine false webworm 30

Pine webworm 30

Nesting pine sawfly 30

Sucking insects

Pine thrips 49

Page

Pine, Austrian—continued

Pine tortoise scale 41

Spotted pine aphid 45

Pine, Eastern White

Borers, root

Pales weevil 64

Pine root collar weevil __ 62

Borers, shoot and stem

Ambrosia beetles 67

Eastern pineshoot borer _ 54

European pine shoot

moth 54

Hylobius congener 64

Lodgepole pine beetle 70

Magdalis perforatus 66

Northern pine weevil 61

Pine engraver 70

Pissodes affinis 62

Pitch mass borer 57

White pine weevil 44

Zimmerman pine moth 56

Borers, wood

Eastern subterranean

termite 78

Melanophila fulvoguttata 73

Monochamus spp. 74

Cone insects

White pine cone beetle 81

Leaf feeders

Imperial moth 27

Introduced pine sawfly 21

Jack pine budworm 32

Pine chafer 24

Pine chrysomelid 24

Pine false webworm 30

Pine tube moth 29

Pine webworm 30

Pine tussock moth 27

Swaine jack pine sawfly _ 19

Tortrix pallorana 33

Walkingstick 26

White pine sawfly 16

Root feeders

White grubs 78

Sucking insects

Pine bark aphid 44

Pine leaf chermid 48

Pine needle scale 42

Pine spittlebug 39

Pineus coloradensis 44

Prociphilus spp. 46

Red spruce aphid 48

White pine aphid 45

208
Page

Pine, Jack

Borers, root

Pales weevil 64

Pine root collar weevil 62

Root tip weevil 63

Warren's collar weevil 64

Borers, shoot and stem

Cimberis elongatus 72

Eastern pineshoot borer _ 54

European pine shoot

moth 54

Jack pine tip beetle 72

Lodgepole terminal

weevil 60

Myeloborus sp. 72

Northern pine weevil 61

Northern pitch twig moth 57

Petrova houseri 58

Petrova pallipennis 55

Pine engraver 70

Pissodes affinis 62

Pitch mass beetle 57

Pityophthorus sp. 72

Red turpentine beetle 69

White pine weevil 59

Zimmerman pine moth 56

Borers, wood

Eastern subterranean

termite 78

Monochamus spp. 74

Prionus sp. 76

Cone insects

Fir coneworm 83

Laspeyresia toreuta 82

Red pine coneworm 82

Spruce coneworm 83

Gall insects

Allegheny mound ant 78

Leaf feeders

Abbott's sawfly 20

Brownheaded jack pine

sawfly 17

European pine sawfly 21

Imperial moth 27

Introduced pine sawfly — 21

Jack pine budworm 32

Jack pine sawfly 18

Neodiprion compar 19

Neodiprion maurus 17

Neodiprion nigroscutum _ 19

Nesting pine sawfly 30

Pine chafer 24

Page

Pine, Jack—continued

Pine chrysomelid 24

Pine false webworm 30

Pine tussock moth 27

Pine webworm 30

Redheaded jack pine

sawfly 17

Redheaded pine sawfly — 16

Red pine sawfly 21

Swaine jack pine sawfly _ 19

Tortrix pallorana 33

Leaf miners

Argyrotaenia tabulana 35

Pine needleminer 34

Pine needle sheathminer _ 84

Root feeders

White grubs 78

Sucking insects

Black pineleaf scale 42

Cecidomyia banksianae 49

Cecidomyia reeksi 49

Clastoptera testacea 40

Gouty pitch midge 50

Pine needle scale 42

Pine spittlebug 39

Pine tortoise scale 41

Pineus coloradensis 44

Saratoga spittlebug 37

Signoret spittlebug 40

Pine, Mugo

Borers, shoot and stem

Eastern pineshoot borer _ 54

Northern pine weevil 61

Pine candle moth 55

Zimmerman pine moth — 56

Leaf feeders

Abbott's sawfly 20

European pine sawfly 21

Jack pine budworm 32

Pine false webworm 30

White pine sawfly 16

Sucking insects

Black pineleaf scale 42

Pine needle scale 42

Woolly pine scale 43

Pine, Ponderosa

Borers, root

Pine root collar weevil

Borers, shoot and stem

European pine shoot

moth

62

54

209
Page

Pine, Ponderosa—continued

Northern pine weevil 61

White pine weevil 59

Zimmerman pine moth 56

Leaf feeders

Abbott's sawfly 20

Argyrotaenia tahulana 35

European pine sawfly 21

Pine needle sheathminer _ 84

Pine, Red

Borers, root

Pales weevil 64

Pine root collar weevil 62

Pitcheating weevil 65

Root tip weevil 63

Warren's collar weevil 64

Borers, shoot and stem

Allegheny mound ant 78

Ambrosia beetles ' 67

Eastern pineshoot borer _ 54

European pine shoot moth 54

Hylobius congener 64

Jack pine tip beetle 72

Magdalis perforatus 66

Northern pine weevil 61

Pine candle moth 55

Pine engraver 70

Pine gall weevil 65

Pissodes affinis 62

Pitch mass beetle 57

Pitch mass borer 57

Red turpentine beetle 69

Rhyacionia adana 54

Rhyacionia busckana 54

Rhyacionia sonia 54

White pine weevil 59

Zimmerman pine moth 56

Borers, wood

Eastern subterranean

termite 78

Monochamus spp. 74

Powder-post beetle 77

Prionus sp. 76

Urocerus spp. 76

Cone insects

Eucosma monitorana 82

Fir coneworm 83

Laspeyresia toreuta 82

Red pine cone beetle 81

Red pine coneworm 82

Rubsaamenia sp. 84

Spruce coneworm 83

Gall Insects

Paa9

Pine, Red—continued

Allegheny mound ant 78

Pine gall weevil 65

Red pine needle midge 50

Leaf feeders

Abbott's sawfly 20

Brownheaded jack pine

sawfly 17

European pine sawfly 21

Grasshoppers 25

Introduced pine sawfly 21

Jack pine budworm 32

Jack pine sawfly 18

Neodiprion compar 19

Nesting pine sawfly 30

Nursery pine sawfly 20

Pine chafer 24

Pine chrysomelid 24

Pine false webworm 30

Pine tussock moth 27

Redheaded pine sawfly 16

Red pine sawfly 21

Swaine jack pine sawfly _ 19

Tortrix pallorana 33

White pine sawfly 16

Leaf miners

Evagora resinosae 35

Pine needleminer 34

Root feeders

White grubs 78

Sucking insects

Clastoptera testacea 40

^^Needle blight" midge __ 51

Pine tortoise scale 41

Pineus coloradensis 44

Prociphilus spp. 46

Red pine needle midge 50

Saratoga spittlebug 37

Setoptus mite 53

Signoret spittlebug 40

Woolly pine scale 43

Pine, Scotch

Borers, root

Pales weevil 64

Pine root collar weevil 62

Root tip weevil 63

Warren's collar weevil 64

Borers, shoot and stem

European pine shoot moth _ 54

Hylobius congener 64

Jack pine tip beetle 72

Magdalis perforatus 66

Northern pine weevil 61

210
Page

Pine, Scotch—continued

Northern pitch twig moth 57

Pine candle moth 55

Pine engraver 70

Pissodes affinis 62

White pine weevil 59

Zimmerman pine moth 56

Borers, wood

Monochamus spp. 74

Powder-post beetles 77

Cone insects

Red pine coneworm 82

Leaf feeders

Abbott's sawfly 20

European pine sawfly 21

Introduced pine sawfly 21

Jack pine budworm 32

Jack pine sawfly 18

Nursery pine sawfly 20

Pine chafer 24

Pine chrysomelid 24

Pine false webworm 30

Swaine jack pine sawfly _ 19

Tortrix pallorana 33

Walkingstick 26

Leaf miners

Pine needleminer 34

Root feeders

White grubs 78

Sucking insects

Balsam twig aphid 45

Cinara pini 45

Pine needle scale 42

Pine spittlebug 39

Pine thrips 49

Pine tortoise scale 41

Pineus coloradensis 44

Saratoga spittlebug 37

Spotted pine aphid 45

White pine aphid 45

Spruce, Black

Borers, shoot and stem

Spruce beetle 71

Northern pine weevil 61

Borers, wood

Melanophila fulvoguttata 73

Cone insects

Spruce coneworm 83

Gall insects

Eastern spruce gall aphid 46

Pine leaf chermid 48

Page

Spruce, Black—continued

Red spruce aphid 48

Spruce gall aphid 46

Woolly larch aphid 47

Leaf feeders

Eastern blackheaded

budworm 32

European spruce sawfly _ 22

Greenheaded spruce

sawfly 22

Spruce budworm 31

Yellowheaded spruce

sawfly 22

Leaf miners

Spruce leafminer (2) 33,34

Spruce needleminer 34

Sucking insects

Spruce bud scale 43

Spruce spider mite 52

Twospotted spider mite _ 52

Spruce, Blue

Borers, shoot and stem

Eastern spruce beetle 71

Northern pine weevil 61

Pitch mass borer 57

Cone insects

Spruce coneworm 83

Spruce seed moth 83

Gall insects

Cooley spruce gall aphid _ 47

Spruce gall aphid 46

Leaf feeders

European spruce sawfly _ 22

Greenheaded spruce

sawfly 22

Spruce budworm 31

Yellowheaded spruce

sawfly 22

Leaf miners

Spruce leafminer (2) ___ 33,34

Spruce needleminer 34

Root feeders

White grubs 78

Sucking insects

Balsam twig aphid 45

Spruce spider mite 52

Twospotted spider mite 52

Spruce, Norway

Borers, shoot and stem

Eastern spruce beetle 71

Northern pine weevil 61

Borers, wood

211
Page

Spruce, Norway—continued

Melanophila fulvoguttata 73

Gall insects

Eastern spruce gall aphid 46

Pine Leaf chermid 48

Spruce gall aphid 46

Leaf feeders

European spruce sawfly _ 22

Spruce budworm 31

Leaf miners

Spruce leafminer (2) ___ 33,34

Twospotted spider mite _ 52

Spruce, White

Borers, root

Pales weevil 64

Borers, shoot and stem

Balsam fir bark beetle 72

Spruce beetle 71

Northern pine weevil 61

Pine engraver 70

Pitch mass borer 57

Small spruce weevil 62

White pine weevil 59

Borers, wood

Eastern subterranean

termite 78

Melanophila fulvoguttata 73

Powder-post beetles 77

Urocerus spp. 76

Cone insects

Spruce cone maggot 84

Spruce coneworm 83

Spruce seed moth 83

Gall insects

Allegheny mound ant 78

Eastern spruce gall aphid 46

Spruce gall aphid 46

Spruce gall midge 51

Leaf feeders

Eastern blackheaded

budworm 32

European spruce sawfly _ 22

Greenheaded spruce

sawfly 22

Pine tussock moth 27

Yellowheaded spruce

sawfly 22

Page

Spruce, White—continued

Leaf miners

Pine needle sheathminer _ 84

Spruce leafminer (2) ___ 33,34

Spruce needleminer 34

Root feeders

Strawberry root weevil 66

White grubs 78

Sucking insects

Pine spittlebug 39

Signoret spittlebug 40

Spruce bud scale 43

Spruce spider mite 52

Tamarack (Larch)

Borers, root

Pales weevil 64

Warren's collar weevil 64

Borers, shoot and stem

Balsam fir bark beetle 72

Eastern larch beetle 70

Borers, wood

Melanophila fulvoguttata 73

Cone insects

Spruce coneworm 83

Leaf feeders

Larch casebearer 35

Larch sawfly 23

Spruce budworm 31

Leaf miners

Larch casebearer 35

Sucking insects

Pine spittlebug 39

Signoret spittlebug 40

Spruce spider mite 52

Woolly larch aphid 47

Yew, Canadian

Leaf feeders

Black vine weevil 66

Strawberry root weevil 66

Root feeders

Black vine weevil 66

Strawberry root weevil 66

Sucking insects

Fletcher scale 42

Pine needle scale 42

Taxus mealybugs 43

212
GLOSSARY

Alternate host. Another host plant required to complete development of an

insect or disease pathogen.

Alternating generations. The habit of some insects that require one generation to develop on one host species and another generation on a different

host species.

Bole. Stem or trunk of a tree.

Cast skins. Shed outer skin of a larva or nymph.

Chip cocoon. A cavity covered with wood splinters that some beetles construct

to conceal the pupa.

Fascicle. Sheath at the base of a needle cluster, surrounding the needles.

Flagging. Discolored shoots or branches.

Frass. Solid insect excrement, usually in small pellets.

Gall. Enlarged, swollen growth of plant tissue.

Gallery. A passage, burrow, or mine excavated by an insect in plant tissue

for feeding, oviposition, or exit.

Honeydew. Sugary liquid excretion of aphid and scales.

Internode. Portion of tree stem or branches between two or more nodes.

Larva. Immature form of an insect such as a caterpillar, grub, or maggot.

Lateral shoots. Side shoots of the tree's branches.

Mined foliage. Leaves or needles in which the inner leaf tissues are eaten

by insects.

Mycelium. Vegetative part of a fungus ; may be threadlike or paperlike.

New growth foliage. Foliage of the current or most recent growing season.

Node. Place on the stem of a tree where major branches are attached; or

place on the branches where major branchlets are attached.

Nymph. Immature form of an insect resembling the adult except for incomplete wing development.

Old growth foliage. Foliage of all seasons except most recent.

Petiole. Stalk of a leaf.

Pole. A tree at least 5.0 inches in diameter at 4l^ feet above the ground.

Prolegs. Fleshy false legs on abdomen of caterpillars; true legs are located

on the thoracic segments behind the head.

Pupa. Inactive stage of an insect; a transition stage from larva to adult.

Pupal case. Shed outer skin of a pupa.

Sapling. A young tree 1 to 5 inches in diameter at 4^/^ feet above the ground.

Sawtimber. Trees that yield logs suitable for lumber; usually measure at

least 8 inches in diameter at 41/4 feet above the ground.

Seedling. Young tree less than 1 inch in diameter at 4^^ feet above the ground.

Skeletonized foliage. Leaves or needles in which the soft tissues have been

eaten by insects from between the veins, leaving only the veins.

Slash. Debris such as logs, bark, branches, etc., left after tree pruning or

cutting.

Terminal shoot. Top-most shoot on the stem tip; also called the leader.

213

GENERAL INDEX

Page

Abbott's sawfly 20

Abnormal temperatures 91

Abnormal water conditions 92

Acantholyda erythrocephala _ 30

Acantholyda zappei 30

Acleris variana 32

Adelges abietis 46

Adelges cooleyi 47

Adelges strobilobius 47

Air pollution 92

Allegheny mound ant 78

Ambrosia beetles 67

Animals 89

Anómala oblivia 24

Ants 77

Aphrophora parallela 39

Aphrophora saratogensis 38

Aphrophora signoreti 40

Arborvitae aphid 45

Arborvitae leafminer 36

Arborvitae sawfly 23

Argyresthia thuiella 36

Argyrotaenia pinatubana 29

Argyrotaenia tabularía 35

Armillaria mellea 89

Aspidiotus abietis 43

Bagworm 29

Balsam bark weevil 62

Balsam fir bark beetle 72

Balsam fir sawfly 21

Balsam gall midge 50

Balsam twig aphid 45

Bark beetles 67

Bears 90

Birds 89

Black carpenter ant 77

Black pineleaf scale 42

Black vine weevil 66

Brachyrhinus ovatus 66

Brachyrhinus sulcatus 66

Branch diseases 86

Brownheaded jack pine sawfly 17

Brown spot 85

Budworm moths 30

Calepiterimerus thujae 53

Camponotus pennsylvanicus _ 77

Cecidomyia banksianae 49

Cecidomyia piniinopis 50

Cecidomyia reeksi 49

Cedar-apple rust 87

Page

Cedar bark beetles 71

Cedar-quince rust 87

Choristoneura fumiferana 31

Choristoneura pinus 32

Chrysobothris orono 57

Cinara pini 45

Cinara sabinae 46

Cinara strobi 45

Cinara tujafilina 45

Clastoptera juniperina 40

Clastoptera testacea 40

Coleophora laricella 35

Coleosporium spp. 85

Commandra blister rust 87

Cone beetles 81

Cone flies 84

Cone insects 80

Cone moths 82

Conifers 4

Conophthorus banksianae 72

Conophthorus coniperda 81

Conophthorus resinosae 81

Cooley spruce gall aphid 47

Cronartium comTuandrae 87

Cronartium comptoniae 88

Cronartium quercuum 87

Cronartium ribicola 87

Dasychira plagiata 27

Dasineura balsamicola 50

Deer 90

Defoliating insects 9

Dendroctonus rufipennis 71

Dendroctonus murryanae 70

Dendroctonus simplex 70

Dendroctonus valens 69

Diapheromera femorata 26

Diaspis carueli 42

Dichomeris marginella 29

Dimerosporium sp. 85

Dioryctria abietella 83

Dioryctria disclusa 82

Dioryctria reniculella 83

Dioryctria zimmernfiani 56

Diprion hercyniae 22

Diprion similis 21

Diseases 85

Eacles imperialis 27

Eastern blackheaded budworm 32

Eastern cedar sawfly 23

Eastern gall rust 87

215
Page

Eastern larch beetle 70

Eastern pineshoot borer 54

Eastern spruce gall aphid 46

Eastern subterranean termite 78

Epinotia nanana 33

Eriophyid mite 53

Eucosma glorióla 54

Eucosma monitorana 82

Eulachnus agilis 45

European pine sawfly 21

European pine shoot moth 54

European spruce sawfly 22

Evagora resinosae 35

Exoteleia nepheos 55

Exoteleia pinifoliella 34

Fir coneworm 83

Flatheaded borers 73

Fletcher scale 42

Foliage diseases 85

Fomes annosus 88

Fomes annosus root rot 88

Formica exsectoides 78

Frost injury 91

Gall aphids 46

Gilpinia frutetorum 20

Glyptoscelis puhescens 24

Gnophothrips sp. 49

Gouty pitch midge 50

Grasshoppers 25

Greenheaded spruce sawfly 22

Gymnosporangium clavipes 87

Gymnosporangium juniperivirginianae 87

Harmful chemicals 91

Hemlock looper 27

Hemlock scale 43

Hemlock twig rust 88

Horntails 76

Human injury 90

Hylobius congener 64

Hylobius pales 64

Hylobius radicis 62

Hylobius rhizophagus 63

Hylobius warreni 64

Hypodermella ampia 85

Imperial moth 27

Introduced pine sawfly 21

Ips pini 70

Jack pine budworm 32

Jack pine sawfly 18

Jack pine tip beetle 72

Juniper scale 42

Juniper tip midge 51

Page

Juniper webworm 29

Lambdina fiscellaria fiscellaria 27

Larch casebearer 35

Larch sawfly 23

Laspeyresia toreuta 82

Laspeyresia youngana 83

Leaf beetles 24

Lecanium fletcheri 42

Lodgepole pine beetle 70

Lodgepole terminal weevil 60

Lophodermium needlecast 86

Lophodermium pinastri 86

Magdalis perforatis 66

Mammals 90

Mayetiola piceae 51

Mechanical injuries 93

Melampsorella spp. 88

Melanophila spp. 73

Melanoplus spp. 25

Mice 89

Midges 49

Mindarus abietinus 45

Mites 51

Monochamus spp. 74

Monoctenus juniperinus 23

Monoctenus melliceps 23

"Needle blight'^ midge 51

Needlecast disease 85

Needle droop 86

Needle miners 33

Needle rusts 85

Neodiprion abbottii 20

Neodiprion abietis 21

Neodiprion compar 19

Neodiprion dubiosis 17

Neodiprion lecontei 16

Neodiprion maurus 17

Neodiprion manulus nanalus _ 21

Neodiprion nigroscutum 19

Neodiprion pinetum 16

Neodiprion pratti banksianae 18

Neodiprion rugifrons 17

Neodiprion sertifer 21

Neodiprion swainei 19

Nesting pine sawfly 30

Noninsect maladies 84

Northern pine weevil 61

Northern pitch twig moth 57

Nuculaspis califomica 42

Nursery pine sawfly 20

Nutrition 92

Oligonychus ununguis 52

Oligothrophus betheli 52

216
Page

Pachylohius picivorus 65

Pales weevil 64

Pegohylemia anthracina 84

Petrova albicapitana 57

Petrova houseri 58

Petrova pallipennis 55

Phalonia rutilaría 36

Phenacaspis pinifoliae 42

Phloeosinus spp. 71

Phyllophaga spp. 78

Physokermes piceae 43

Pikonema alaskensis 22

Pikonema dimmockii 22

Pine bark aphid 44

Pine candle moth 55

Pine chafer 24

Pine chrysomelid 24

Pine engraver 70

Pine false webworm 30

Pine gall weevil 65

Pine grosbeak 89

Pine leaf chermid 48

Pine needleminer 34

Pine needle scale 42

Pine needle sheathminer 84

Pine root collar weevil 62

Pine shoot moths 54

Pine spittlebug 39

Pine thrips 49

Pine tortoise scale 41

Pine tube moth 29

Pine tussock moth 27

Pine webworm 30

Pineus coloradensis 44

Pineus floccus 48

Pineus pinifoliae 48

Pineus similis 48

Pineus strobi 44

Pissodes affinis 62

Pissodes approximatus 61

Pissodes dubius 62

Pissodes rotundatus 62

Pissodes strobi 59

Pissodes terminalis 60

Pitcheating weevil 65

Pitch mass beetle _^ 57

Pitch mass borer 57

Pitch-mass making insects 56

Pitch midges 49

Pityokteines sparsus 72

Plant lice 44

Pocket gophers 90

Podapion gallicola 65

Page

Porcupines 90

Powder-post beetles 77

Pristiphora erichsonii 23

Prociphilus spp. 46

Pseudococcus spp. 43

Pseudophilippia quaintancii _ 43

Pulicalvaria abietisella 36

Pulicalvaria piceaella 34

Pulvinaria (?) sp. 43

Rabbits 90

Red cedar aphid 46

Redheaded jack pine sawfly 17

Redheaded pine sawfly 16

Red pine cone beetle 81

Red pine coneworm 82

Red pine needle midge 50

Red pine sawfly 21

Red spruce aphid 48

Red turpentine beetle 69

Reticulitermes flavipes 78

Rhyacionia buoliana 54

Phyacionia spp. 54

Root aphids 46

Root diseases 88

Root insects 53

Root tip weevil 63

Roundheaded borers 74

Rubsaamenia sp. 84

Salt injury 91

Sapsucking insects 36

Saratoga spittlebug 37

Sawflies 9

Scales 41

Scirrhia acicola 85

Scleroderris canker 86

Scleroderris lagerbergii 86

Setoptus sp. 53

Shoestring root rot 89

Shoot insects 53

Shoot moths 53

Signoret spittlebug 40

Sm.all spruce weevil 62

Smoke injury 92

Sooty mold 85

Spittlebugs 37

Spotted pine aphid 45

Spruce beetle 71

Spruce bud scale 43

Spruce budworm 31

Spruce cone maggot 84

Spruce coneworm 83

Spruce gall aphids 46

Spruce gall midge 51

217
Page

Spruce leafminer 33, 34

Spruce needleminer 34

Spruce seed moth 83

Spruce spider mite 52

Squirrels 90

Stem insects 53

Stephanopachys spp. 77

Strawberry root weevil 66

Swaine jack pine sawfly 19

Sweetfern rust 88

Taniva albolineana 34

Taxus mealybugs 43

Termites 77

Tetralopha robustella 30

Tetranychus urticae 52

Thecodiplosis piniresinosae 50

Thrips 49

Thyridopteryx

epheTneraeformis 29

Tipdwarf mite 53

Tortrix pallorana 33

Toumeyella numismaticum 41

Trypodendron sp. 72

Page

Twospotted spider mite 52

Tubeworms 28

Urocerus spp. • 76

Vespamima pini 57

Walkingstick 26

Warren's collar weevil 64

Webworms 28

Weevils 58

White grubs 78

White pine aphid 45

White pine blister rust 87

White pine cone beetle 81

White pine sawfly 16

White pine weevil 59

Witches'-brooms 88

Wood borers 73

Woodpeckers 89

Wood-rotting fungi 89

Woolly larch aphid 47

Woolly pine scale 43

Yellowheaded spruce sawfly _ 22

Zelleria haimhachi 34

Zimmerman pine moth 56

^ U.S. GOVERNMENT PRINTING OFFICE: 1977 D 221-229

218