INSEa-PESTS

OF DECIDUOUS FRUITS

IN THE WEST

ÍUABÜIÍSE»«»-

Agriculture Handbook No. 306

Agricultural Research Service

UNITED STATES DEPARTMENT OF AGRICULTURE

NAL DIGITIZING PROJECT

MBP0000259

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OF DECIDUOUS FRUITS

IN THE WEST; J

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Agriculture M^ndbook üb. 306 y //

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UNKiD STATES DEPARTMENT OF AGRICULTURE^
CONTENTS

Page

Apple and pear insects 1

Peach and apricot insects 28

Cherry insects 38

Prune and plum insects 43

Beneficial insects 50

List of orchard insects 53

Index 55

This handbook contains information formerly published in

Circular 270, Orchard Insects of the Pacific Northwest and

Their Control.

Washington^^p.C. Issued August 1966^

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

Washington, D.C. 20402 - Price 30 cents
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST

By E. J. NEWCOMER, collaborator, Entomology Research Division, Agricultural

Research Service

Insects take a toll of many million dollars a year in the deciduous

orchards of the West. The annual

value of the fruit crops is nearly

$300 million. The cost of combating insect pests and the losses due

to infested fruit are estimated at 10

percent of this amount.

Knowledge of the insects and

mites found in these orchards—

their life history and habits—is of

vital interest to fruit growers.

This handbook gives such information about most of the insects and

mites found in the orchards west of

the Rocky Mountains and the damage they cause. A list of these

pests, including the recognized common names and the scientific names,

is given on page 53.

APPLE AND PEAR INSECTS

Codling Moth

The codling moth has caused

greater losses to apple and pear

growers than any other pest. It is

present in all the deciduous fruitgrowing districts of the West. It

was accidentally introduced from

Europe into the Eastern States and

then transmitted to the Pacific

coast.

Type of Injury.—This insect is

injurious only in the larval, or

worm, stage. The young worms

crawl to the fruit nearest them, burrow into it, and produce the familiar wormy apple or pear. Many

worms enter through the calyx end,

where the calyx protects them and

they can easily obtain a foothold;

others enter at a point where two

fruits touch, or where a leaf touches

a fruit; and still others burrow into

the exposed side of the fruit. The

worm penetrates the skin and within an hour excavates a small cavity.

It remains near the surface for a

few days and then burrows to the

center of the fruit, usually feeding

on the seeds and core. When full

grown the worm tunnels to the surface and leaves the fruit. Wormy

fruit is of small commercial value,

as it will not keep long, and the laws

of some States forbid its shipment,

except to byproducts plants.

Another form of injury known as

the sting is caused by a worm that

begins to burrow into the fruit and

then dies, usually from feeding on

a slow-acting poison spray on the

fruit. Large stings may cause the

fruit to be classified as culls, and

small stings will lower its grade.

Life History.—The codling moth

winters as a worm in a cocoon (fig.

1) about three-fourths inch long.

The cocoon may be under the loose

bark of trees, in cracks and crevices

on trunks, attached to the trunk just

below the surface of the ground, or

in protected places in boxes, sacks,

and packing sheds. The worm just

about fills the cocoon and is grayish

white or pinkish, with a brown head.
AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

F.I. 3195 AND P.I. 3196

FIGURE 1.—Codling moth : A, Larva and

pupa in cocoons ; B, adult ( Enlarged. )

The last brood of worms that leaves

the fruit before it is packed and a

part of the preceding brood hibernate. In the spring the worms construct exit tubes of silk, transform

to pupae, and later to moths, which

escape through the exit tubes.

The first moths appear about the

time Winesap apple trees are in

bloom, and the largest numbers are

flying in May or early in June. The

moths (fig. 1) are rather inconspicuous, with a wing spread of about

three-fourths inch. The front or

upper wings are brownish gray,

crossed with lines of lighter gray,

and have a bronze band at the tip.

The hindwings, which are covered

when the moths are at rest, are grayish brown. The moths live for about

2 weeks. They lay most of their

eggs between sundown and 9 or 10

p.m., but lay few eggs if the temperature is below 60° F- Most of

the eggs are laid during the second.

third, and fourth evenings after the

moths have emerged, but in the

spring, cool weather may prevent

egg laying altogether for a week or

more.

The eggs (fig. 2) are pearly white,

about the size of pinheads, and resemble thin convex disks. A red

ring appears in the egg a few days

after it is laid. The day before the

worm hatches, a black spot, the head

of the worm, is easily seen. Most of

the first-brood eggs are laid on

leaves near the small fruits.

Usually the weather is cool when

the first eggs are laid, and the worms

do not hatch for 12 to 14 days. As

the temperature increases, the incuFiGURE 2.—Eggs of codling moth : A, On

apple leaf (natural size) ; B, single

egg (greatly enlarged).
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST

bation period becomes shorter; the

minimum is 4 days. Worms are

hatching and entering the fruit for

about 5 weeks, and are most numerous during June. They feed in the

fruit for about 3 weeks and then

leave it and spin cocoons. About 75

percent of them develop into pupae

and moths, but the others remain in

the cocoons until the following season. The worms thattransform pass

througli the pupal period in about

2 weeks, and the first individuals of

the second brood of moths appear

early in July.

After this time moths are present

in large numbers until cool weather,

and the first stormy weather in September usually ends their activities

for the season. Many eggs of the

second brood are laid on the fruit,

and during July and August they

ordinarily hatch in 6 or 7 days. The

worms often remain in the fruit for

more than a month in the fall, and

many of them are still there when

it is picked. They may leave the

fruit before it is packed, and large

numbers of cocoons may be found

in picking boxes and packing sheds.

The codling moth is sensitive to

variations in temperature. In warm

localities there is often a partial

third generation, but at higher elevations and along the coast there

is no third generation and the second generation is smaller than elsewhere. In any locality the yearly

abundance of worms varies greatly,

as it is dependent on weather conditions. Temperatures of —15° F.

or colder kill some of the overwintering worms. Probably the

effect of temperature is most evident during May and June, when

large numbers of first-brood eggs

are laid if the weather is warm, but

the number is greatly reduced if it

is cold or rainy. Thus an early

warm season produces many worms,

but a late cool season has the opposite effect.

The fruit grower should therefore

study weather conditions as well as

conditions in his orchard and plan

his spraying.schedule accordingly.

San Jose Scale

Type of Injury.—The San Jose

scale can do more damage than any

other insect in the orchards of the

West. Besides rendering the fruit

unmarketable, it kills the twigs and

limbs. If not controlled, it may

even eventually kill the tree or at

least so weaken it that it is worthless. Actually the San Jose scale

does little damage, because control

is easy and fruit growers generally

know the danger and keep the scale

under control.

This insect sucks the plant juices

from the twigs and larger branches

and from the fruit and foliage. It

causes small reddish spots, particularly on the fruit, wliich often are

the first indication that the scale is

present (fig. 3). The red discoloration also occurs on scale-infested

leaves and in the bark. It cannot be

seen on the surface of the bark, but

is disclosed by cutting into infested

P.X. 2374

FIGURE 3.—San Jose scales on pear.
AGRICULTURE HANDBOOK 3 0 6, U.S. DEPT. OF AGRICULTURE

FIGURE 4.—San Jose scale: A, Bark encrusted with scales ; B, scales magnified.

twigs or limbs. The bark is roughened and grayish (fig. 4). If it is

scraped, a yellowish liquid appears

from the crushed bodies of the insects. Infestations are also manifested by dead twigs scattered about

the tree and by the tendency of the

leaves on infested branches to remain on the trees during the winter.

In irrigated districts, however,

leaves often remain on uninfested

apple trees for at least a part of the

winter.

Although present methods of control are adequate and are keeping

the scale in check, an infestation

should not be regarded lightly. If

spraying is neglected, the scales can

become very numerous in a surprisingly short time, as a single female

and her progeny may produce several million scales in one season.

Laws in some States prohibit the

marketing of infested fruit except

for making byproducts, and quarantine regulations prohibit the entrance of infested fruit into certain

foreign countries.

The San Jose scale is present in

practically all the fruit districts of

the United States; it was introduced

accidentally about 1870 from China.

It does most harm to apple and

pear, but is at times a serious pest

of sweet cherry, peach, and prune.

It also attacks other deciduous fruit

trees, as well as nut trees, beri-y

bushes, and many kinds of shade

trees and ornamental shrubs, among

them the mountain ash, currant,

dogwood, elm, gooseberry, hawthorn, lilac, linden, poplar, snowberry, willow, and the ornamental

flowering varieties of fruit trees.

Many of these plants or trees grow

in the gardens or about the houses

in fruit-growing districts, and unless they are inspected regularly and

sprayed, if infested, they may be

troublesome centers of infestation

for nearby orchards.

Life History.—The San Jose scale

remains in one place during most of

its life. Almost all stages may be

found on the trees in the fall, but

only those scales that are about half

grown survive the winter, and in

severe winters many of them succumb. Temperatures of —15° to

— 20° F. kill approximately twothirds of the half-grown scales, and

90 percent or more are killed if the

temperature reaches —25° or —30°.

In the spring the surviving scales

continue their growth and mature in

May or June. The males develop

wings and are active, although they

do little flying. The females have

no wings. They remain where they

develop and produce several hundred very small, louselike, yellowish, active young. These young insects crawl considerable distances

during the first few hours of their

lives. Often they are carried to

other trees by the wind, on the feet

of birds, on the clothing of men

working in the orchards, or on

horses or farm implements. Ordinarily they settle down within a few

hours on the bark or on leaves or

fruit, insert their long, tiireadlike

beaks into the plant tissiie, and begin feeding.

Almost at once they begin to

secrete a waxy material, which soon

forms a circular, scalelike covering.

The covering of the full-grown fe-
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST

male is <ibout tlie size of a pinhead

and f^rayish, with a dark, central

nipplelike projection, whereas that

of the male is elongated (fifj. 4).

Underneath these coverings the

delicate, bright-yellow, s a c 1 i k e

bodies of the insects may be seen.

Growth is completed in about 6

weeks, and there are two or more

generations a season.

Oystershell Scale

The oystershell scale is found

throughout the West, but occurs

most commonly in the more humid

regions. It is readily distinguishable from other scale insects by its

characteristic shape (fig. 5).

Type of Injury.—The apple is a

favorite food plant, but this scale

also lives on many other fruit trees,

as well as shade trees, ornamental

shrubs and plants, and on native

trees, such as willow and dogwood.

Its damage to the tree and fruit is

similar to that of the San Jose scale.

FIGURE .5.—Oystershell scale : .4, Twig encrusted with scales ; ß, old scale turned

over to show eggs. ( Enlarged. )

and heavily encrusted trees or limbs

may be killed.

Life Hixtory.—If the old scales

on the bark are turned over during

the winter, they will be found filled

with small, pearly-white eggs (fig.

5). Often there are nearly 100 eggs

beneath a single scale. The eggs

hatch shortly after the apple trees

bloom, and the minute, whitish

young crawl out and settle in a few

hours on some living part of the

plant. They develop slowly, increasing the size of the scale coverings as they grow. The covering of

the female is about one-eighth inch

long when completed, dark brownish gray, and shaped somewhat like

an oystershell. The covering of the

male is smaller and oval, and the

mature males emerge from the scales

with fully developed wings. The

females spend their entire lives

beneath the scale coverings, depositing eggs under them in the fall before they die.

Other Scale Insects

The Italian pear scale is found in

most of the pear-growing districts

of California, but it is not often a

major pest. It lives mostly on pear

but may also occur on apple.

This scale hides in crevices in the

bark or under moss or lichens, and

it may not be noticed until it begins

to affect the tree. Superficially it

looks like the San Jose scale, but the

soft body of the female is dark reddish purple instead of yellow. It

winters mostly as a mature insect.

The olive scale is most prevalent

in the San Joaquin Valley of California. It thrives on over 200 species of plants, including olive,

peach, plum, nectarine, apricot, and

apple. The scale covering is ovate

or circular and gray. The insect

beneath it is reddish or purple. It

does not hide beneath lichens and
6 AGKICXJLTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

moss as does the Italian peiir scale,

and it does not infest pear.

The European fruit lecanium infests pear and rarely apple in California. It is hemispherical, about

one-fourth incli in diameter, and

brown. It occurs chiefly on the

twigs. For a description of its habits and life histoiy, see page 4.'5.

The calico scale is also occasionally seen on pear in C!alifornia. It

is similar to the European fruit

lecanium, but distinguishable from

it by the irregular white lines on

its back (fig. 6). Its injury is also

similar. The vigor of the trees niay

be reduced and honeydew will develop, which may injure the fruit.

This scale wintei-s on the twigs as

a partly grown insect and reaches

maturity in early May. Numerous

eggs are laid >mder tlie female scale.

The crawlers go to the leaves, feeding tliere during the summer and

returning to the twigs in the fall.

There is one brood each year.

Tlie cottony maple scale (fig. 7)

sometimes becomes rather common

on Winter Nelis and d'Anjou pear

in the Noi-tliwest, but doas not seem

to thrive on Bartlett, and is very

seldom seen on apple. It is j^rimarily a pest of maple, as its name

indicates, and also lives on grape,

boxelder, blackberry, and a variety

of other plants. It is a native of

Europe, and came to the United

States over 100 years ago. The insect is easily recognized by the cottony egg sac, which the female produces in the early summer and

which often remains for some time.

PIOTJRE 6.—Calico scales (onlargcd).

(Courtesy California Agricultural Experiment Station.)

FIGURE 7.- -Cottony maple scales on pear

twig.
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST

About 3,000 eggs laid in this sac

hatch during June and July. Tlie

young scales settle on the underside

of the leaves, where the male insects

mature. Tlie partly grown females, which are oval, flattened, and

greenish or yellowish, migrate to

the twigs in the fall and hibernate

there. They complete their growth

in the spring, when they are brown,

rather convex, and about one-eighth

inch in diameter. The egg sac is

formed gradually as the eggs are

laid, and the females die when oviposition is completed. There is

only one generation a year.

The grape mealybug (fig. 8) lives

on various plants, but has been primarily a pest of grapes. It also

lives on pear and sometimes on apple and apricot. The eggs are laid

early in the fall in a cottony mass

on the scaffold limbs. The eggs

hatch in the fall, but the young

crawlers remain in the cottony jirotection through the winter. They

start feeding early in the spring beneath the scales of the swelling buds.

AVlien full grown these insects are

about one-fourth inch long and dark

purple. They are covered with a

white, powdery wax and have

slender, white filaments protruding

from the body. Oviposition occurs

late in June beneath the bark scales

and at the base of new growth. This

second generation becomas adult by

late summer, and some injury may

result from honeydew dripping onto the fruit. On pears the mealybugs also crawl into the calyx end,

and the feeding there causes a

breakdown of the tissues.

Pear Psylla

The pear psylla was first found in

the United States in Connecticut in

1832, evidently having come from

Europe. It has be«n a pest of pear

east of the Mississippi River for

many years, but wsis not found in

P.I. 1602

FIGURE 8.—Graiw mealybuR.

the West until 1939. It has now

spread to practically all pear-growing districts on the Pacific coast.

Type of Injury.—Injury is limited to pears. Honeydew secreted

by these insects runs down over the

foliage and fruit, and a sooty fungus grows in it. This causes the

skin to become blackened and

scarred, and the foliage develops

brown spots. Severe infestations

may cause partial defoliation of the

trees, reducing vitality and preventing the formation of fruit buds.

There is now strong evidence that

the psylla is associated with the

spread of pear decline by injection

of a toxin or as a vector of a causative virus or both.

Life History.—Adult pear psyllas

(fig. 9) have somewhat the appearance of miniature cicadas, with

transparent wings sloping over the

body. They are about one-tenth

inch long and dark reddish brown.

They can fly away suddenly from

where they are resting, giving the

impression that they have jumped.

Hibernation is in the adult stage in

crevices in the bark or under leaves

or. the ground. Tlie adults may become active at any time when the

temperature is above 40° F.

207-597 O - 66
8 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICXTLTURE

FIGURE 9.—Pear psylla : A, Adult ; B, eggs : C, large nymphs. ( Courtesy New York

Agricultural Experimeut Station.)
INSECT PESTS OF DECIDUOUS FRUITS IX THE WEST 9

The elongated, whitisli or yellow

eggs (fig. 9) are deposited in March,

or sometimes even earlier, in the

small crevices about the buds. After

the foliage is out, many of the eggs

are laid on the leaves. Each female

may produce as many as 500 eggs.

They hatch in 10 to .30 days.

The young nymphs migrate to the

axil of the leaves and to the leaves

themselves to feed. The nymphs

(fig. 9) are yellowish and flattened,

and soon cover themselves with the

honeydew they secrete. They go

through five immature stages, becoming greenish as they grow larger

and finally brownish black in the

last, or "hard-shell," stage (fig. 10).

FIGURE 10.—"Hard-shell" stage of pear

psylla.

Often these hard shells congregate

in large numbers on the water

sprouts and other tender growth.

There are three to five generations

a year, each one lasting about 30

days. The psylla thrives best in cool

weather. Adequate control is often

difficult, and any treatment must be

carefully timed and thoroughly

applied.

Orchard Mites

Type of Injury.—Orchard mites

or red spiders do great damage to

apple and pear trees, much of it

difficult to measure. They feed by

withdrawing the contents of the leaf

cells, including the chlorophyll, and

tlius cause a whitening or mottling

of the leaves, which finally become

browned or bronzed. In nonirrigated orchards complete or partial

defoliation frequently results. The

leaves of pear, particularly d'Anjou,

Winter Nelis, and Bosc, often brown

and dry up during the first extremely hot weather in the summer.

Although this condition is probably due chiefly to the inability of

the tree to supply moisture fast

enough during the sudden onset of

hot weather, it may be aggravated

by a severe infestation of mites,

since they remove large quantities

of moisture from the leaves. As the

trees manufacture their food supply

largely in their leaves, any foliage

injury will reduce the vitality of

the tree and consequently the size

of the fruit, even if it does not cause

the leaves to drop off.

Life History.—Six important species of mites infest orchards in the

West. Two are of European origin

and the others are native.

The McDaniel spider mite (fig.

11) is at times the most serious pest

the grower hasto combat. The webbing it spins often collects dust and

gives the foliage a dry, dusty apl^earance. This species winters as

an adult in leaves and trash on the

ground. In the spring the surviving mites migrate into the trees, first

attacking the foliage nearest the

ground and gradually extending

tlieir operations over tlie entire tree.

The mites are usually greenish or

yellowish while feeding, often with

two dark spots on the body. The

eggs, which are almost colorless, are

laid in the webbing. The young resemble the adults, except for the

newly hatched mites, which have

only six legs instead of eight. They

develop from egg to adult in a week
10 AGRICULTURE HANDBOOK 306, U.iS. DEPT. OF AGRICULTURE

FIGURE 11.—Adult of McDaniel spider

mite (greatly enlarged).

or 10 days, and there are several

generations a year. The mites can

therefore become exceedingly numerous in one season. Late in July

or in August, particularly if the

infestation is severe and the mites

are crowded, many of the adults

cease feeding, become reddish or

orange, and migrate to their hibernating places. Since this migration

is downward, many of them collect

around the calyx end of apples,

where they spin webbing that takes

on the appearance of cellophane.

This species thrives on many

kinds of fruit trees and also on a

milkweed (Asclepias) and other

weeds that grow in the orchards, but

it is especially injurious to apple.

The Pacific spider mite occurs in

orchards, mostly in California, and

is similar in appearance and habit

to the McDaniel mite.

The two-spotted spider mite occurs throughout the West, and it infests a great many plants or trees,

including alfalfa, vegetable crops,

berries, melons, deciduous fruit and

nut trees, flowering plants, and

weeds. In appearance it is similar

to the McDaniel spider mite, and

is scarcely distinguishable from that

species without microscopic examination. It may have two rather

definite black spots on the back,

which may sometimes cover most of

the body, and its color may vary

from yellowish or pale green to reddish. Its habits and life history are

similar to those of the McDaniel

spider mite.

The yellow spider mite is particularly^ injurious to apple and pear

in the Hood River and Rogue River

Valleys of Oregon. It also occurs

elsewhere but is not often a serious

pest. These spider mites are smaller

than the others and are pale yellow

or green with a few dark spots.

They tend to congregate along the

midribs and larger veins of leaves.

The eggs are spherical and translucent. Wintering females are

bright lemon yellow.

The European red mite lays

bright-red overwintering eggs on

the twigs and branches of fruit

trees. When numerous, these eggs

are very noticeable as reddish

patches on the bark. They are also

found in the calyx end of mature

apples (fig. 12). These eggs hatch

just before the blossoms open. The

mites feed on the foliage, usually

on the underside, and spin very

little webbing. They are more easily seen than the other spider mites;

they are velvety or brownish red,

with conspicuous, whitish, curved

spines on the back. During the

summer the eggs are laid on the

leaves, and there are seven or eight

generations a season. This species

is seldom found on anything except

deciduous fruit and nut trees.

The brown mite (fig. 13) also winters in the egg stage. The eggs are

slightly larger than those of the

European red mite, but not distinguishable from them with the naked

eye. They hatch about a week earl-
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 11

FIGURE 12.—Winter eggs of European red mite in calyx end of apple (enlarged).

ier. Otherwise the habits and life

liistory of the two species are much

alike. The brown mites spin no

webbin<r. Tliey usually confjregate

in roufrhened places on the twigs and

branches during the day and migrate to the leaves at night to feed.

This habit of feeding at night and

the lack of webbing make them

rather inconspicuous, and usually

the whitening of the leaves caused

by their feeding is the first evidence

of their presence. The adults are

dull reddish or greenisli and are

flatter and have longer legs than the

European red mites. They are

found chiefly on deciduous fruit

trees.

Pear Leaf Blister Mite

Tyfe of Injury.—The pear leaf

blister mite is a common pest of

pear and sometimes of apple

throughovit tiie AVest. It produces

small galls or blisters on the leaves,

and it also lives in the buds and in

the skin of the fruit. At first the

leaf galls are greenish or reddish,

but later they turn brown and cause

dead areas. These areas may be

distinguished from apple scab by

the small round holes on the undersurface of tlie leaf api)roximately in

the center of each blister (fig. 14).

Since the mites begin feeding in

the leaves before they are fully

opened, the new leaves show the

blistei-s at once. If the mites are

numerous, many of the leaves later

dry and drop ort'. The fruit of the

a])])le is more seriously affected than

that of the pear. It is attacked

when it is young, and the injuries

cause mature fruit to be russeted or
12 AGRICULTURE HANDBOOK 3 06, U.S. DEFT. OF AGRICULTURE

FIGURE 13.—Adult of brown mite

(greatly enlarged).

appearance. It also causes the

leaves to roll lengthwise. The fruit

may be attacked and become

russeted.

This mite is so small it can

scarcely be seen with the naked eye.

Under a lens it is found to be shorter

and more triangular than the pear

leaf blister mite. Instead of producing blisters, this mite feeds on

the leaf surface during the growing

season and hibernates in the buds

and in crevices on the bark. In California there is a second species

known as Bailey's apple rust mite,

which has the same habits.

The pear rust mite is very similar

to the species on apple. It may cause

the leaves to turn brown, particularly on young trees, but the cliief

deformed and sometimes to crack

open. The mites also injure and

deform the blossoms.

Life Hvitory.—The adult mites

winter under the scales of fruit and

leaf buds. They are less than onehundredth inch long. Under a lens

they appear as elongated, whitish,

wormlike creatures, with four legs

near the head end (fig. 14). Often

hundreds of them can be found in

a single bud. In warm spring

weather when the buds begm to

swell, the mites lay eggs in them,

and the young burrow into the

unfolding leaves and form the characteristic blisters. They feed entirely within the blisters, and a succession of generations develops,

practically out of reach of sprays.

With the approach of cold weather,

the mites migrate to the buds, where

they hibernate beneath the scales.

Rust Mites

The apple rust mite is very small

and not unlike the pear leaf blister

mite. It feeds on the undersurface

of apple leaves, giving tliem a rusty

FIGURE 14.—Pear leaf bli.^ter mite : A, Infestation on apple leaf; B, adults

(greatly enlarged).
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 13

injury comes from its feeding on

the fruit. Heavy infestations will

cause the pears to become entirely

russeted.

Woolly Apple Aphid

Tyfe of Injury.—The woolly

apple aphid occurs in practically

all apple-growing districts. It attacks the roots as well as the upper

part of the trees. Above ground

it is found chiefly on the trunks,

limbs, and twigs, in wounds caused

by pruning or cultivating implements, and wherever the bark is

tender (fig. 15). Twigs become

somewhat swollen and knotted from

its attacks. The aphids are occasionally found on the fruit stems

and in the calyx end of apples. In

the arid, sandy areas of the Northwest, roots are not often injured ; the

injury is usually to exposed roots.

In the coastal sections and in California, particularly in heavy soil

that may crack, the aphids penetrate to the roots, causing swellings

and deformities (fig. 16) that may

hinder the growth of the tree.

FiGlIKE 15.- -Aerial coliiny

apple aphid.

of wooU.v

FIGURE 16.—Nodular api)le roots resulting from attack by woolly apple aphid.

The colonies of aphids appear as

bluish-white, woolly patches, which

are composed of the reddish insects

covered with woolly masses of wax.

When the aphids are numerous, this

waxy material, which contains some

honeydew excreted by the insects,

hangs in festoons, smears the fruit,

and makes picking a disagreeable

job. In districts where the perennial canker disease occurs, aphids

feeding above ground apparently

prevent the healing of cankers.

Life History.—The woolly apple

aphid hibernates on the roots of

apple trees, and many of those on

the upper part of the trees also survive in mild climates or during mild

winters. Infestations above wound

may thus come from wintering

forms already present there or from

migrants from the roots. Heavy infestations are likely to follow mild

winters. The aphids multiply

rapidly, and new colonies are established by winged forms flying to

other apple trees or by young aphids

carried from tree to tree by the wind

or other means. The parasite ApheUnusmali (Haldeman) would eifectively control the woolly apple

aphid if it were not for the insecticides that are applied to control

other pests. But often the parasites
14 AGRICULTURE HANDBOOK 3 0 6, U.S. DEPT. OF AGRICULTURE

develop rapidly in the fall after

spraying has been completed, and

they may then reduce the infestation

of apliids to a low point.

Rosy Apple Aphid

Type of Injury.—The rosy apple

aphid feeds only on apple and on

its alternate summer host, the plantain or ribgrass. It curls the leaves,

particularly those on the fruit spurs,

and infests the young fiiiit, causing

it to become stunted and distorted

(fig. 17). These aphid-injured apples do not thin out normally during the June drop, and in the fall,

clusters of them are often conspicuous, especially on the lower and inner parts of the trees. At times they

are numerous enough to reduce the

marketable crop. This aphid was

probably introduced from Europe.

Life History.—The rosy apple

aphid winters in the egg stage on

apple trees, and the eggs hatch in

FlOUBB 17.- -Apples stunted by rosy apple

aphid.

the spring when the buds begin to

swell. The young start feeding in

the unfolding fniit buds, causing

the leaves to curl as they develop.

Several generations a year are produced on the apple, and they feed on

the leaves and the fruit. The species may be distinguished by its

purplish or rosy-brown color and by

its habit of curling the leaves and

deforming the fmit. As the weather

becomes warmer, brownish-green

winged individuals develop and migrate to the plantain. Most of the

aphids have left the apple trees by

early July. They do not migrate

to other apple trees, and therefore

trees not bearing winter eggs remain free of infestation. On the

]>lantain several generations of yellowish-green aphids occur, and in

the fall winged forms again develop

and fly back to the apple trees,

where they produce a wingless generation of aphids. These aphids deposit eggs on the twigs, in the axil

of the buds, and in crevices in the

bark. At first the eggs are pale

green but later become shiny black.

Apple Aphid

Type of Injury.—The apple

aphid, formerly known as the green

apple apliid, lives on apple throughout the year and feeds mostly on

the succulent terminal twigs (fig.

18), curling the leaves and stunting

the growing shoots. It is thus injurious chiefly to nursery stock and

to young trees, although it sometimes becomes sufficiently numerous

on bearing trees to hinder normal

growth. It occasionally infests pear

trees. This aphid, which came from

Europe, is now found in the United

States wherever apples are grown.

Life II'iHtory.—The apple aphid

winters in tlie egg stage in the same

manner as the rosy apple aphid, although the eggs are more likely to

be found on water sprouts than on
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 15

P.I. son

FIGURE ]8.—Apple aphids on apple foliage.

other parts of tlie tree. The eggs

hatch at about the same time as do

those of the rosy apple aphid, and

tliere may be from 9 to 17 generations a year. Young and adults are

green with black legs, and some have

yellowish heads. Some of the adults

are winged, and these migrate to

other apple trees, thus spreading the

infestation during the season. The

eggs are green when deposited in the

fall, but later become glossy black.

Other Aphids

The apple grain aphid lives on

grains and grasses during most of

its active life, but goes to apple in

the fall to deposit its winter eggs.

These eggs are not easily distinguished from those of the two preceding species. They hatch early in

tlie spring, and the fii-st generation

lives on apple and then migrates to

grasses. The adults differ from

those of the apple aphid by having

207-597 O - 66 - 3

dark bands across the body. This

species is particularly troublesome

in Colorado.

In the coastal districts and interior valleys of California, and sometimes elsewhere, several otlier species of aphids may be found on pear.

The green peach aphid is light

green, the melon aphid is usually

dark green, and the bean aphid is

black. They feed primarily on the

new growth of the trees, curling the

leaves, stunting the growth, and

producing honeydew. This may

drip onto the fniit and cause some

russeting. These aphids, which

feed primarily on other plants, may

live on pear only a month or so, and

therefore they do not ordinarily

cause much damage.

The woolly pear aphid lives on the

roots of pear. It does not ordinarily do much harm, but a heavy

infestation could affect the vigor of

the trees. There are other causes for

lack of vigor, but this pest should

be considered as a possible cause if

trees are not growing nonnally.

AVinged forms develop in the fall

and deposit eggs on elm trees. The

young emerge in the spring and feed

on the leaves, causing them to be deformed and gall-like. "Winged

adults develop in June and July and

fly to pear trees, where they deposit

young on the trunks. These migrate to tlie roots, completing the

cycle. Winglass forms also inhabit

the pear roots, at least in California

the year around.

Pear Thrips

The pear thrips occurs in most

fruit-growing regions of the AVest.

It was at one time one of the most

important insect pests of pear in

California, and it can cause severe

injury if not held in check. The

injury occurs in two ways. Adult

thrips, which are almost black,

emerge from the soil in the spring
16 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

and feed in the opening buds, causing them to drop. Later, the larvae, which are white, feed on the

developing fruit, russeting or scarring the skin. For information on

the life history and apjiearance of

this pest, see page 46.

There are several other species of

thrips attacking apple and pear.

These include the bean thrips in

California and the flower thrips in

the Northwest.

Treehoppers

Type of Infwry.—Young orchards containing alfalfa or clover

cover crops are subject to the attacks of several species of treehoppers. The most injurious are

the buffalo treehopper, the green

clover treehopper, and the darkcolored treehopper (fig. 19). The

injury consists of wounds and scars

made by the female when laying her

eggs in the bark of the trees (fig.

20). The female cuts slits, which

are roughened and ragged or cleancut, depending on the species. The

injury rarely extends more than 6 or

8 feet above the ground, and young

trees are most often attacked.

Frequently the growth of such trees

is seriously retarded. Injury is

practically confined to the current

season's growth and to 1-year-old

wood, but the old scars persist for

some years. Apple and pear are

most subject to injury, although

peach, cherry, plum, and quince are

occasionally affected.

Life HhtoTnj.—The whitish cylindrical eggs of the treehoppers are

about one-tentli inch long, and from

6 to 20 of them are placed side by

side in each slit, with the ends usually visible. They are deposited

from July to September and hatch

the following April or May. The

young, or nymphs, drop to the

ground and feed chiefly on alfalfa,

where they are most often found in

F.t. 907S

FIGURE 19.—A, Buffalo treehopper; B,

green clover treehopi)er ; C, darkcolored treehopper. (Enlarged.)

the center of the crowns. Growth

is completed in July. The adult

insects are about three-eighths inch

long, grayish or greenish, and triangular, and the commoner species

have jirojecting pronotal horns,

suggesting the appearance of a

buffalo.

Leafhoppers

Type of Injwy.—Tlie leafhoppers, like orchard mites, are sucking

msects feeding only on the foliage

of apple. They withdraw the

chlorophyll and other cell contents,

leaving tlie foliage whitened or mottled. Slight foliage injury by

leaflioppei-s and mites is of no consequence, but as soon as the foliage

is reduced below the amount required for the crop, tlie fruit and

buds are directly affected. The
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 17

FIGURE 20.—Apple twig scarred by green

clover treehoppers in laying eggs.

fruit fails to reach normal size, and

the buds are weakened so that they

may not set fruit the next season.

It is therefore important to prevent

extensive injury.

Life History.—The rose and

apple leafhoppers are prevalent in

the Pacific Northwest and may also

be found in California. Both ai-e

native to the United States. The

more common and important of

tliese is the rose leafhopper, a slender, active, whitish insect about oneeifrhth incli lon<r. It winters in the

e<rfï sta<re in the bark of the trees.

The epfTS hatch in April and early

May, and the small white lioppers

befrin to feed at once on the new

foliage, remaining in the pubescence

of the underside of the leaves,

(îrowth is attained in 8 to 6 weeks,

and the adults live for -2 months.

Eggs are laid in the tissue of the

leaves from May to -Tuly, and hatch

in about a montli. The second

brood of young thus appears late

in July and in August, and adults

are present again from August to

November. These lay wintering

eggs in the bark of the young wood,

where they appear as small raised

blisters.

The apple leafhopper (fig. 21)

has only one generation a year, beginning with tlie wintering eggs,

which are usually laid in the bark

of wood 2 or 3 years old. Tlie eggs

hatch in April or May. The young,

which are light green instead of

white, feed in the same manner as

do the rose leafhoppers. The green

adults appear in Alay and some are

still present in July. Most of the

FiGURK 21.—Adult (if apple leafhopper

(greatly enlarged).
18 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

egjis are deposited in June and July,

ami these remain in the bark until

the following; April. As it has only

a sinjîle «reneration annually, this

leafhopper does not become so numerous as the white species.

Sucking Bugs

Lygus bugs sometimes cause considerable injury to pear (fig. 22)

and Delicious apple, particularly in

the Northwest. For a description

of these bugs, see page 36.

FiGUBE 22.—Toung .pears injured by

lygns bugs.

Boxelder bugs (fig. 23) are flat

and black with red lines and are

about one-half inch long. Occasionally clusters of these bugs will be

found feeding on the maturing fruit

of apple and pear, chiefly in the

vicinity of boxelder trees. The

adults hibernate in swarms in crevices of trees and buildings. The

young, which hatch from eggs laid

m the spring, feed on the boxelder

trees. These trees are of two

kinds—those that bear seeds and

those that do not—and only the

latter should be planted, as the bugs

live mostly on the former. Seedbearing trees near orchards should

be removed.

Consperse stink bugs (fig. 24)

are about one-half inch long, shield

shaped, gray brown, covered with

small black dots, and with yellow

M & A 12045

FIGURE 23.—Adult of boxelder bug

(enlarged).

or red antennae. They feed on

fruits, mostly pears, but also to some

extent on apricots, plums, and

peaclies. This may cause some of

the fruit to drop, but the chief damage comes from the formation of

dry, corky areas under the skin

where feeding has occurred. These

bugs overwinter as adults. They

lay white barrel-shaped eggs in

clusters on various broadleaved

plants, on which the young feed.

These young are at first black and

white, later becoming yellow or

brown. The new brood of adults

appears by mid-June, and from then

until harvest may be found feeding

on the fruit. Several other species

of stink bugs occasionally cause

similar injury.

The apple lacebiig is a pest of

apples in AVashington and Oregon.

The young and adults feed on the

lower surface of tlie leaves, usiuilly

in groujw. They dot the leaves with

black spots of excrement, and as

tlie insects suck tiie juices, the leaves

become yellowed and eventually

drop. The adults are about one-
INSECT PESTS OF DECIDUOUS FRUITS IX THE "WEST 19

FIGURE 24.—Adult of consperse stink

bug. (Courtesy California Agricultural Experiment Station.)

eightli inch long, grayish, flattened,

and with lacelike wings. Eggs are

laid on the leaves, and there are

probably two or more generations

annually.

Fruit-Tree Leaf Roller

Ty])e of Injury.—The fruit-tree

leaf roller feeds primarily on apple,

but also on most of the other deciduous fruit trees. The small caterpillars feed on the unfolding leaves,

webbing them together and forming

a protection for themselves. This

webbing often covers the blossom

buds, causing considerable injury

by preventing normal blooming.

As the caterpillars become larger,

they roll up one or more large leaves

and include some of the fruit in the

webbing, making a sort of nest.

Tliey feed within this, eating large,

irregular lióles in tlie fruit and

foliage. In extreme cases they practically defoliate the trees and cause

a total crop loss.

In regions where much spraying

is done for the codling moth and

the San Jose scale, tlie fruit-tree

leaf roller has not been an important pest, but occasionally very

serious outbreaks have occurred

elsewhere and may occur again. In

the past the insect has periodically

become of prime importance, remained .so for a few years, and then

subsided into relative unimportance.

It is a native insect, which originally fed on the foliage of several

wild plants.

Life Ilintory.—The fruit-tree leaf

roller winters in the egg stage. The

eggs are laid during June and July

in masses of 100 or more. They are

rather inconspicuous, oval, grayish

or brownish patches, nearly onefourth inch long, on the limbs,

twigs, and trunks of the trees. The

eggs hatch as soon as the buds begin

to open. The caterpillars ai'e active,

crawling backward about as rapidly

as forward, and often drop to the

ground on a thread if disturbed.

They become full grown in June.

At that time they are about threefourths inch long, green, and with

black heads. Tliey transform to

brown pupae in the rolled-up leaves,

and the moths emerge about 10 or 12

days later. These are a little larger

than codling moths. The e.xpanded

wings measure about three-fourths

inch across. They are rusty brown,

with several irregular yellowish

bands across them. There is one

generation a year.

Oblique-Banded Leaf Roller

The oblique-banded leaf roller

has two generations a year; a brood

of caterpillars a])peai-s in Álay and

June and another in July and August. The habits and appearance of

the caterpillars are similar to those

of the fruit-tree leaf roller. However, the moths are slightly larger

and cinnamon brown, with a darker

oblique band across each forewing.
20 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

This species is usually less injurious

than the fruit-tree leaf roller to

apple and other deciduous fruit

trees.

Orange Tortrix

In the coastal fruit-growing districts of California, surface injury

to fruits of apple and pear is sometimes seen, which is caused by the

feeding of an insect larva. This is

the orange tortrix, primarily a pest

of citrus. For a description of the

appearance and habits of this insect,

see page 32.

Tent Caterpillars

Type of Injury.—Tent caterpillars are found on apple in California and in the coastal areas of the

Northwest. They appear in May

and June, constructing tents of

webbing in the crotch or about the

smaller twigs and leaves of the trees.

They feed voraciously during the

day, devouring all the leaf tissue except the midribs, and retire at night

to the tents or collect in masses on

the larger limbs. These caterpillars

occur sporadically and in some

years are numerous enough to defoliate not only fruit trees but wild

growth and shade trees as well.

Life History.-—The insect winters

in the eçrg stage. The eggs are laid

in masses surrounding the twigs,

each mass containing several hundred eggs covered with a frothy,

waterproof material. The young

caterpillars appear about the time

the apple buds oegin to open. The

group hatching from a single egg

mass consti-ucts a small silken nest

or tent, and as the caterpillai-s grow

this nest is enlarged to provide adequate protection for the colony.

The caterpillai"s are somewhat

hairy, tawny brown, and with a row

of blue spots flanked by orange spots

along the back. When full grown

they are nearly 2 inches long. As

the caterpillars become larger they

tend to scatter, and their cocoons

may be spun in various sheltered

places, such as under loose bark, in

curled leaves, or under projecting

eaV'BS of nearby buildings. The

cocoons are tightly woven of yellow

silk, surrounded with a loose mass

of silk. The moths emerge in June

or July and soon deposit the wintering egg masses.

Fall Webworm

Although the habits of the fall

webworm are somewhat similar to

those of the tent caterpillar, the two

insects can be easily distinguished.

The fall webworm appears late in

July and constructs a loose, unsightly nest of webbing about several twigs (fig. 25). These nests

are extended as the caterpillars

grow and often enclose entire

branches. The caterpillars feed

within the webs, devouring the

leaves and fruit. When full grown

the caterpillar is about 1^ inches

ir.I. 31)63

FIGURE 25.—Nest of fall webworm.
INSECT PESTS OF DECIDUOUS FRUITS IX THE WEST 21

long, covered with long, whitish

hairs, and has a dark hand along the

back. It constructs a flimsy, brown

cocoon in trash on the ground.

From this cocoon the moth emerges

in the following summer. The

moth is usually pure white or

spotted with dark dots. It lays

f)ale-green eggs in a flat mass on a

eaf, covering them with wiiite hairs

from its body. The eggs hatch in

about 10 days. There is only one

brood annually. The insect occurs

on over a hundred different fruit

and shade trees in Idaho, California, and the area west of the Cascade Range.

Tussock Moths

The rusty tussock moth and the

western tussock moth are leaf-feeding insects occurring chiefly in California and west of the Cascade

Range. The first species winters in

the egg stage in dry leaves or on

tree trunks or twigs. The caterpillars appear in April. They subsist mainly on the foliage, but occasionally damage the fruit, and may

be found on shrubs and a great variety of deciduous fruit and shade

trees. They feed for a month or

more, and when full grown are

about 1 inch long, hairy, blackish or

bluish, and have several thick

tufts of hairs along the back (fig.

26). The male moth has rustybrown wings, but the female is

wingless. She deposits her eggs in

a mass on the cocoon from which

she emerged. A second brood of

caterpillars appears late in July

and produces moths in September.

These in turn deposit the wintering

eggs. The western tussock moth

has similar habits, except it has a

single brood each year. The eggs

laid in July hatch the following

spring. Special control is seldom

necessary, since sprays applied for

other leaf-feeding caterpillars keep

FioTTRE 26.—Caterpillar of tussock mcitli.

these insects in check. Many of the

egg masses may be found and destroyed when the trees are pruned.

Other Caterpillars

The red-humped caterpillar may

occasionally feed gregariously on

ai)ple and pear in midsummer. The

caterpillars are reddish with dark

tubercles and longitudinal lines of

white, brown, red, and black. The

liead and tmirtli segment, which is

humped, are bright red. Hibernation is in tlie pupal stage in the

ground. The moths emerge in the

spring and lay masses of pearlywliite eggs on the leaves.

The yellow-necked caterpillar occui-s on ajijile, pear, quince, cherry,

and many shade and forest trees,

mostly in California. Its iiabits are

similar to those of the preceding

species. The caterpillars are black

witii four yellow longitudinal

strii>es, long whitisli hairs, and a

bright-yellow or o r ange neck.

Wlien disturbed they characteristically raise botli ends of their body.
22 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

Cankerworms, sometimes called

measuring worms, are about an inch

long when mature and green with

yellow stripes. There are two

species, each with only one generation. The spring cankerworm

winters in the pupal stage and the

fall cankerworm winters in the egg

stage. These worms are found

chiefly in California on the same

kind of fruits and trees as the yellow-necked caterpillar.

Sometimes smooth green worms,

an inch or so long, will be found eating large holes in developing apples

or pears (fig. 27). These are the

green fruitworms. They are most

often seen during May and June.

The fruit that is attacked may drop

off, or if the cavities are shallow,

they heal over and result in russeted

scars. Wlien the worms are full

P.I. 3391

FIGURE 27.—Green fruitworm feeding on

apple.

grown, they make cells in the

ground, where they transfonn to

brown jnipae in a manner similar to

that of the cutworms. The moths

emerge late in the fall or early in

the spring and lay eggs singly on

the trees. Control measures are not

often needed.

In western Oregon and in the

Hood River Valley the apple leaf

miner may be found in leaves of

apple and wild hawthorn. It constructs blotchlike mines in the leaf

between the large veins and causes

the leaf to become somewhat misshapen. The adult is a very small,

silvery moth, which lays eggs on the

leaves. The young worm burrows

between the upper and lower leaf

surfaces, formmg the mine. When

full grown it pupates within the

mine, and the motli emerges soon

after. There are two or more broods

a season. In the fall the worms make

silken hibemacula in the mines,

where they spend the winter in the

fallen leaves. This pest is of minor

importance. Any cleaning up or

cultivation that destroys or buries

the leaves late in the fall would prevent many of the moths from emerging the following spring.

In nortliem California the tentiform leaf miner (fig. 28) attacks

pears, skeletonizing the leaves. At

times more than lialf the leaf tissue

may be destroyed, which would prevent the fruit from attaining normal size. The habits of this insect

are similar to those of the apple leaf

miner, except there are four generations a year.

The serpentine or apple fruit

miner is more of a curiosity than a

pest. The adult is a very small

moth, the young of which foim

winding whitisli mines just under

the skin of the apple. The mines

are also occasionally found on

prunes. This insect occurs so rarely

that control measures are not

necessary.
INSECT PESTS OF DECIDUOUS FRUITS EST THE WEST 23

f.1^ t ^ * i 9-:<^f-ij'-*

FIGURE 28.—Tentlform leaf miner : A, Adult ; B, larva ; C, pupa ; D, Injury to pear

foliage.

207-597 O
24 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

The apple leaf trumpet miner

sometimes causes a trumpet-shaped

injury on apple foliage in western

Oregon. This pest is of minor importance. Any cultivation that destroys or buries the leaves late in

the fall would prevent many of the

moths from emerging in the spring.

Another larva that injures the

foliage of apple and pear in the

western parts of Oregon and AVashington is tlie apple-and-thom skeletonizer. It also feeds on cherry and

hawthorn. The adult is a small

dark-brown moth, which hibernates

and deposits eggs early in the

spring. The small caterpillars feed

on the underside of the leaves first;

later they feed on the upper surface

and construct shelters by drawing

the leaves together with silk. The

injured leaf becomes a mass of webbing and frass. There are several

generations a year.

The eye-spotted bud moth occurs

in California, Montana, Idaho, eastern Washington, and the region

west of the Cascade Range in Washington and Oregon. The injury to

the fruit, which is caused by the

larvae, consists of irregular surface

feeding or a series of small holes in

the skm (fig. 29). It is seldom of

any great importance on apple,

î'or further information, see page

47.

(^limbing cutworms occasionally

attack apple and pear, but are more

injurious to peach. For a description of these insects, see page 32.

Pear-Slug

Type of Injury.—The pear-slug

feeds on the foliage of pear and

cherry, skeletonizing the leaves by

eating the >ipper surface (fig. 30).

The larvae are slimy and sluglike,

olive green or almost black, and

about one-half inch long when full

grown. Wlien they are numerous,

the entire tree becomes brown, as

FIGURE 29.—Holes in apple made

larvae of eye-.spotted bud moth.

by FIGURE 30.—Pear-slii;; and it.s injury to

leaf (enlarged).
IN^SECT PE'OTS OF DEICIDUOITS FRUITS IN THE WEST 25

though swept by fire. This damage

should be prevented, as the reduced

leaf surface seriously interferes

with the growth of the fruit and

with the development of fruit buds.

This insect is widely distributed in

the United States. It originated in

Europe.

Life History.—The adults are

glossy black four-winged flies and

about one-fifth inch long. They

are known as sawflies, because they

cut slits in the upper surface of the

leaves, in which the eggs are laid.

The eggs in the leaves look like

small blisters. The young slugs

hatch in a week or two and feed almost entirely on the upper surface,

usually avoiding any leaves that

may have been attacked by aphids

or blister mites. Just after molting,

the slugs are yellow, but they soon

secrete a slime that gives them the

characteristic black or olive-green

color. Their bodies are somewhat

enlarged in front and taper behind.

The slugs complete their growth in

less than a month, drop to the

ground, and form cells in the soil,

within which they transform to

adults in a couple of weeks. The

second brood of slugs appears on

the trees in August, and when full

grown they spend the winter in

earthen cells from which the adult

sawflies emerge the following

spring.

Syneta Leaf Beetle

Type of Injury.—The syneta leaf

beetle seldom injures apples, but

may reduce the pear crop 50 percent

or more. The injury consists of

scars and deformities on the fruit

caused by the beetles when feeding.

The beetles also chew the fruit stems

and cause some of the fruit to drop.

Practically all the injury is done

during April and May.

Life History.—The life history of

the beetle is discussed on page 42.

California Pear-Slug

Type of Injury.—Holes onefourth inch or more in diameter are

sometimes found in pear leaves in

late April or in May. A close examination will usually show a green

w^orm stretched along the edge of

each hole, feeding on the leaf (fig.

31). This is the California pearslug, which occurs throughout the

Pacific Northwest and in California.

Life History.—^^The adult insects

are sawflies similar in appearance

to those of the pear-slug, but somewhat more slender and with some

yellowish markings. They emerge

from the ground early in April and

cut slits in the lower surface of the

partly unfolded leaves, in which

the eggs are laid. The wounds often

cause the leaves to become deformed. The small green worms

hatch in 10 days or 2 weeks and feed

on the leaves. There is only one

generation a year.

Dock Sawfly

In Washington, apples are occasionally found in the fall with round

holes in them resembling those made

by full-grown codling moth larvae.

If the fruit is cut open, a brightgreen worm may be seen inside (fig.

32). This is the larva of the dock

sawfly, an insect that has come from

Europe. The young worms feed entirely on dock and related plants.

When full grown they search for

suitable places in which to transform to adults. Usually they burrow into the dry, hollow, or pithy

stems of plants. But if apples are

nearby, and particularly if they are

hanging low in the cover crop, the

worms may burrow into the apples

instead of the plant stems. The injury caused by this insect is ordinarily negligible.
26 AGRICULTURE HAJSTDBOOK 306, U.S. DEPT. OF AGRICULTURE

FIGURE 31.—California pear-slug: A, Full-grown larva (enlarged) ; B, injury to leaf;

C, egg in tissue and young larva feeding (enlarged).

Flatheaded Borers

Two species of flatheaded

borers—^the flatheaded apple tree

borer and the Pacific flatheaded

borer—occur on apple and pear.

They are very similar. The adult

beetles are flattened and dark greenish blue or dark bronze with coppery spots. The larvae, or borers,

are most often injurious to young

trees, particularly those that are

weakened from sunburn or other

causes. They are waxy white, about

an inch long when full grown, legless, and with the forepart of the

body broad and flat (fig. 33). The

beetles emerge in the spring and lay

eggs on the tree trunks, preferably

in the sun. The young borers burrow into the bark and require a year

or more for complete development.

Both species are native American

insects.

Trees should be keptin a resistant,

healthy condition, as the young

borers are unable to thrive in vigorous trees with strong-flowing sap.

If the trunks of young trees are protected with whitewash, or if a board
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 27

FIGURE 32.—Larva of dock sawfly in

apple.

or stave is placed so that it will

shade the trunk, danger of injury

will be reduced.

Other Borers

Small round holes, like shot holes,

are sometimes found in the bark of

apple and pear. They are made by

small black scolytid beetles known

as sliot-hole borers, usually only

unhealthy trees are attneked. The

borers rarely eat into the fruit itself.

For further information about these

insects, see page ^5.

The bronze apple tree weevil attacks devitalized apple and prune

trees, making several small holes in

a patch in the bark. These are egg

punctures, and the grubs hatching

from tlie eggs feetl beneath the bark,

causing a sunken, discolored area

about the size of a silver dollar. The

adult beetles, which are small,

bronzy or black, and have snouts,

emerge the following spring.

FiouBE 33.—Larva of flatheaded apple

tree borer (slightly enlarged).

The American plum borer is occasionally seen on pear in California, and it also attacks plum and

other deciduous fruits. The matiire

larvae resemble those of the codling

moth, but they live in the bark of

trees that already have some other

injury. The adult moths have a

wingspread of about one-half inch

and are gray with brown and black

markings.

Rain Beetles

Type of Inivn/.—In the Ilooti

River Valley of Oregon, the grubs

of two species of rain beetles feed

on the roots of apple and pear, sometimes causing sevei-e injury. Affected trees make little growth and

the foliage may become yellowed.

These or allied species also sometimes attack apple and pear in

southern Washington and in California. The grubs feed on the

fibrous roots and also on the larger

roots, where they eat patclies of the

bark or make long, winding bands.

Sometimes the roots are girdled.

Life Hilary.—The grubs are

whitish with brown heads and vary

from nearly one-half inch long when
28 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

first hatched to almost 21/2 inches

when full grown (fig. 34). Growth

is slow and grubs may live 9 to 12

Ïears. Pupation is deep in the soil,

'he pupae are about li^ inches in

length. The beetles (fig. 34) are

about an inch long and reddish

brown to black. They emerge in

late fall during or after rains, mate,

and the females then remain in the

soil, depositing eggs from May to

July of the following year. The

oval eggs, which are about one-fifth

inch long, hatch in about 60 days.

Ants

Orchards in the West are sometimes inhabited by ants, particularly the large, pugnacious red ants

{Formica spp.). They build nests

in the ground, which are often covered with rather conspicuous heaps

of dried stems and twigs of plants.

These ants are attracted to the trees,

primarily to feed on the honeydew

excreted by aphids and other insects. At times the ants may chew

the blossoms and cause direct injury.

Grasshoppers

Grasshoppers occasionally eat the

leaves of young orchard trees to the

extent that their growth is affected.

They do not ordinarily cause much

injury to mature trees.

FIGURE 34.—Rain beetle: A, Full-grown larva (greatly enlarged); B, adults (enlarged). (Courtesy Oregon Agricultural Experiment Station.)

PEACH AND APRICOT INSECTS

Green Peach Aphid

Type of Injury.-—^Peach crops are

sometimes seriously reduced by

large numbers of green peach

aphids feeding in the opening blossoms. These sucking insects remove

the juices from the newly formed

fruit causing it to drop. They also

curl the leaves and prevent them

from developing normally. It is

important, therefore, that control

measures be taken early, as little

or no injury occurs later on. The

green peach aphid came from Europe and is common in all the peachgrowing districts in the West.

Life History.—The glossy-black

wintering eggs may be found on

twigs, in the axil of buds, and in

crevices of bark of peach trees.

They hatch early in the spring, and

the pinkish young commence feeding at once on the opening buds,

pushing their way into the unfolding blossoms and between the devel-
INSECrr PESTS OF DECIDUOUS FRUITS IN THE WEST 29

oping leaves. The second and

third generations are green, and the

latter acquire wings and migrate to

summer food plants, which include

many of the common vegetables and

ornamental plants, such as cabbage,

cucumber, lettuce, potato, tomato,

turnip, carnation, chrysanthemum,

snapdragon, and violet. In the

fall, winged forms return to peach

and produce a wingless generation,

which lays the overwintering eggs.

Black Peach Aphid

Type of Injury.—The black peach

aphid is occasionally seen in the

West. It was introduced from the

Eastern States, where it is native.

It feeds on the roots and leaves of

peach and apricot, and is therefore

potentially a pest of considerable

importance, since root-feeding

forms are often more difficult to

control than those above ground.

Life History.—The black wingless forms live on the roots throughout the year, and in the spring some

of them migrate to the new growth

above ground, where they increase

rapidly (fig. 35). As they become

crowded, winged forms develop,

which fly to other trees and establish new infestations. The aerial

forms usually disappear by midsummer.

Mealy Plum Aphid

The mealy plum apliid may be

found on the underside of apricot

leaves during the summer. For information on this aphid, see page

44.

Orchard Mites

Orchard mites, including the twospotted spider mite, the brown mite,

and the European red mite, injure

peach, but are not often found on

apricot. In the interior valleys of

Cfalifornia, the Pacific spider mite

FiGUBB 35.—Black peach aphids on peach

shoot.

may also be found on peach and

apricot. It is similar to the twospotted spider mite. For information on these mites, see page 9.

Peach Silver Mite

A silvering of peach leaves is

usually the result of prolonged feeding on them by the peacli silver mite.

Tiiis is an extremely small mite, but

it may be seen with a hand lens. It

is wliitish and somewhat triangular

and will be found on botli surfaces

of the leaves, usually near the veins

or midrib. It wintei-s around tlie

lateral buds several inches Ix-low tlie

terminals, invading the expanding

buds and newly formed leaves in tlie

spring. There are several broods

a year.
30 AGRICXJ1.TURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

Peach Twig Borer

Type of Injury.—R i p e n i n g

peaches and apricots are sometimes

•wormy, and this worminess may be

associated with a split pit. The

brown worms in these fruits are

peach twig borers, so named because

early in the spring the young worms

burrow into the tender terminal

growth of the trees and cause the

rapidly growing twigs to wilt (fig.

36). In this way they interfere

with the development of new

growth. Their presence in the fruit

causes a direct loss. The peacli twig

borer also attacks prune trees, and

the twig injury is especially serious

on nursery trees or in young orchards. The species originated in

Europe and has been in the United

States for many years.

Life History.—The young peach

FIGURE 36.—Peach shoot injured by peach

twig borer.

twig borers winter in very small

silk-lined burrows, or hibemacula,

in the bark. These are usually constructed in the folded bark found in

the crotch of younger branches.

Each burrow has a characteristic

projecting tube or "chimney," composed of silk and tiny pieces of bark,

which is difficult to see without a

lens. The small worms leave these

winter quarters as soon as twig

growth has commenced and burrow

into the new shoots, where they feed

on the pith and inner bark and cause

the shoot to wilt. Frequently a

single worm injures several twigs in

this manner.

By April or May the worms are

mature, nearly one-half inch long,

and reddish brown. They spin loose

cocoons in rough places in the bark

or in curled leaves, and the small, inconspicuous, grayish moths emerge

in May or June. These lay minute

eggs on the bark, and the tiny

worms hatching from them attack

the fruit as well as the new growth.

They usually burrow into the fruit

near the stem end and feed around

the pit ; or, if this is still soft, they

enter it and feed on the kernel. This

second brood of worms also produces a brood of moths, which lays

eggs, and the young worms hatching

from them build the silken burrows

in which they overwinter.

Oriental Fruit Moth

An infestation of the oriental

fruit moth (fig. 37) was found in

California in 1942. Moths were

first caught in baits in Idaho and

Colorado in 1944 and in Oregon and

Washington in 1945. In 1948 the

first infestation was found in Washington. This pest was first discovered in the United States in 1916,

having been accidentally brought

from Japan in shipments of flowering cherry, peach, or other trees.

It is now present in most of tlie
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 31

F^GtJRE 37.—Adult of oriental fruit moth

(eularifed).

£each-growing districts of the

Tnited States.

Type of Injury.—The only injurious stage of the oriental fruit

moth is the larva, or worm. The

young wonns burrow into the

rapidly growing twigs near the tip

and feed on the central core. (fig.

38). They also enter the fruit, particularly near the end of the season,

either through the stem or the side,

and feed on the flesh around the pit

(fig. 39). The worms usually leave

through holes in the side, from

which considerable gum exudes.

Injury to the twigs prevents the tree

from growing normally, as it may

send out several lateral twigs just

below the injury. Injury to the

fruit usually ruins it for consumption.

The oriental fruit moth at times

causes serious lossas to peach, which

is its principal food. It also attacks the other deciduous fruits, but

does not usually cause much injury

to them. It has not been as injurious in the West as it is in the

East.

P.I. 4796

FIGURE 38.—Peach twigs injured by oriental fruit moth.

F.I. 4r.3r>

FIGURE 39.—Larva of orient;»! fruit moth

in jieach.

l.'ife IJixfor!/.—The oriental fruit

moth wintei-s in much the same

manner as tlie codling moth—tliat

is, as a full-grown worm in a cfX'oon
32 AGRICULTURE HAN^DBOOK 3 06, U.S. DEPT. OF AGRTCULTURB

on the tree or in leaves or stems on

the ground. The worms are pinkish with brownish heads. This

color distinguishes them from the

larvae of the peach twig borer,

which are reddish brown. They

look much like the larvae of the

codling moth, but are smaller when

full grown. They may be distinguished definitely by microscopic

examination of the anal segments.

The oriental fruit moth larva has

a black anal comb on the dorsum of

the last segment; this is lacking on

the larva of the codling moth (fig.

40). The moths emerge in the

spring shortly before the peach

trees are in bloom. They fly for

about a month. Eggs are usually

laid singly on the upper surface of

the leaves. There may be four to

seven generations a year in the

West.

Pandemis Moth

The larvae of the pandemis moth

sometimes seriously injure ripening

apricots in Washington. For a discussion of this insect, see page 41.

Fruit-Tree Leaf Roller

The fruit-tree leaf roller is sometimes an important pest of apricot

in parts of the West. It feeds principally on the foliage but also attacks the fruit. It may feed on the

FIGURE 40.—Anal segments of larvae : A,

Oriental fruit moth; B, codling moth.

(After Garman.)

surface protected by a leaf that has

been tied to the fruit or it may make

deeper inroads, sometimes penetrating to the pit. Such fruits are

rendered worthless. It has only one

generation each year. For more information on the life history and

habits of this pest, see page 19.

Orange Toitrix

Type of Injury.—Although primarily a pest of citrus, the orange

tortrix also attacks deciduous fruits,

particularly apricots, pears, and

apples. The larva is essentially a

leaf roller, feeding on and rolling

the leaves, but also damaging the

fruit. Feeding here is on the surface at the stem end, where two

fruits touch, or where a leaf is in

contact with the fruit.

Life History,—^Hibernation is

usually in the larval stage in nests

constructed in dry leaves or in

mummified fruits. Some of these

insects overwinter in other stages,

so that there is an overlapping of

broods during the summer, and all

stages may be found at the same

time. There may be two to four

generations. The adults are about

one-fourth inch long, bell shaped

when at rest, tan or rusty brown,

and with a black chevron on the

wings. Eggs are laid in overlapping masses of 10 to 40 on smooth

bark. The greenish black-headed

larva (fig. 41) is very active when

disturbed, wriggling about and

dropping on a silk thread. This

pest occurs chiefly in California.

Climbing Cutworms

Type of Injury,—In the spring,

orchardists sometimes find that the

opening buds on their trees are being eaten and often entirely devoured, although no insects capable

of causing the injury are visible (fig.

42). A careful search among the
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 33

FIGURE 41.—Larva of orange tortrix.

(Courtesy California Agricultural Experiment Station.)

leaves or trash at the base of the tree

will probably disclose the culprits.

Tliey are climbing cutworms. These

smooth, grayish-brown or blackish,

greasy-looking worms are usually

curled up. They range in length

from y^ to 11/2 inches when stretched

out. They lie quietly just beneath

the soil, under a leaf, or in a bunch

of grass or alfalfa during the day

and climb into trees at night to feed

on the tender leaves and flower parts

of expanding buds. Frequently

their presence is made known by

many buds and parts of buds that

were dropped on the ground under

the trees by the worms as tiiey feed.

At times dozens and even hundreds

of these worms may be found in the

daytime under each tree, and such

numbers cause severe damage.

Life TI'iHtory.—Several species of

cutworms, including the spotted

cutworm (fig. 43), are responsible

for most of the damage of tliis type

(lone to fruit trees. Their habits

are similar. Most of them spend

tlie winter as small partly grown

worms, coming out of hibernation

FIGURE 42.—Peach buds .showing holes

made by climbing cutworm.«.

in tlie spring voraciously hungry.

For a time the tender buds of fruit

trees offer a very attractive food

supply, and most of tlie damage is

caused over a relatively .short period.

Later the wonns feed on alfalfa and

other ground i)lants. When full

grown they construct cells in the

soil, where they pupate, and tlie

oi-ange-brown pupae are often

turned up when the soil is plowed

or spaded. The motlis emerge at

various times during the summer
34 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRTCULTURE'

FIGURE 43.—Spotted cutworm : A, Moth ;

B, larva extended; G, larva curled.

(Enlarged.)

and are among the fairly large, dullgrayish or brownish moths seen flying about lights at night. There

may be one or more generations a

f'ear, but later generations are of

ittle consequence, as vegetation is

plentiful by the time they appear.

Eggs are deposited in the fall on the

trees or cover crops in patches of a

hundred or more. After hatching,

the small worms feed for a time before hibernating.

Other Caterpillars

Several other caterpillars may occasionally feed on apricots. These

include the green fruitworms (see

p. 22), the cankerworms (see p. 22),

and the caterpillars of the tussock

moth (seep. 21).

San Jose Scale

The San Jose scale is not so injurious to peach as to pear and apple, and it seldom injures apricot.

For a description of this scale insect, see page 8.

Black Scale

Type of Injury.—The black scale

(fig. 44) is a common pest of apricot in California and it also lives on

FIGURE 44.—Immature black scales on

twig (enlarged). (Courtesy California Agricultural Experiment Station.)

olive, citrus, and many other plants.

It may cause serious damage by removing sap from the tree and by

producing honeydew, which disfigures the fruit and in which a

black fungus grows.

Life History.—The female scales

winter in a partlj^ grown condition

and reach maturity in April and

May. The full-grown scales, which

will be found on the twigs and

branches, are hemispherical, oneeighth to one-fourth inch in diameter, usually black, and with ridges

on the dorsum forming a letter H.

Eggs are laid under the mature female, and one insect may produce

several thousand of them. The eggs

are round and pearly white. The

crawlers emerge in June, move to

the leaves, and develop slowly during the summer. In the fall they

move back to the twigs before the

leaves drop and develop into the

partially grown wintering scales.

There is only one brood a year in

the apricot-growing districts.
INSECT PE'OTS OF DEICIDUOÜS FRUITS m THE WEiST 35

Other Scales and Mealybugs

The European fruit lecanium attacks peach and apricot as well as

other deciduous fruits. In California it is often associated with the

black scale, but differs from it in being shiny brown and without the H

mark. For a description of this

scale, see page 43.

In California several other scales

may be found on apricot, but none

are of great importance. These include the frosted scale, the brown

soft scale, the olive scale (see p. 5),

the oystershell scale (see p. 5), the

Howard scale, and the Putnam scale.

The grape mealybug sometimes

infests apricot, particularly in the

coastal areas of California. Damage is caused chiefly by the honeydew, which drips onto the fruit and

in which a black fungus grows. For

a description of this pest, see page

7.

Peach Tree Borer

Type of Injury.—The peach tree

borer and the western variety of the

same species are serious pests of

peach and apricot, as well as of

prune, plum, and occasionally

cherry. The injury occurs chiefly

in the crown and roots of the trees,

where the borers tunnel beneath the

surface, feeding on the inner or

growing layer of bark. Young trees

may be completely girdled and

killed. Older trees are frequently

so weakened that they become subject to other insect pests or to diseases. The presence of borers in the

trees is often first indicated by a

quantity of gum at the base of the

trunk, mixed with dirt and frass.

Poor condition of the trees may also

indicate the presence of the borers.

Trees should be examined periodically for borers, especially if they

are not making good growth or do

not appear to be thrifty.

Life History.—The adult is a

steel-blue moth with a wing expanse

of more than an inch. The wings

of the male moth are clear, except

for the margins, but the forewings

of the female are opaque. The female of the eastern form has an

orange band about the abdomen,

whereas the entire abdomen of the

western form is steely blue. The

male moth of the eastern form has

several narrow yellow bands on the

abdomen and yellow markings on

the wings; these do not appear on

males of the western variety.

Otherwise the two forms are similar

in appearance and habits.

In California the moths first appear in May and continue to emerge

until September. In other parts of

the West they do not appear until

June or July. They fly about

actively during the warm part of

the day. Each female lays several

hundred oval, cinnamon-b r o w n

eggs, singly or in groups on the tree

trunks. The eggs hatch in about

10 days, and the young borers crawl

down the trunks and enter the damp

bark just beneath the surface of the

soil. At once they begin feeding on

the inner bark and continue doing so

until late in the fall, remaining in

the burrows during the winter. In

the spring, feeding is reôumed, and

the borers become full grown in May

and June, when they are about 1

inch long, yellowish white or cream

colored, with brown heads (fig. 45).

They construct cocoons of silk and

frass at the surface of the soil, either

in their tunnels or close to the trunk,

within which they change to pupae

and several weeks later to moths.

There is only one generation annually.

Shot-Hole Borers

Two kinds of shot-hole borers occur in the West. They attack the

wood of all the deciduous fruit trees
36 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

FIGURE 45.—Full-grown i)each tree borers

and injury to peach trunk (enlarged).

(fig. 46), preferring wood that is

unhealthy or dying due to mechanical or winter injury, improper

watering, insects, or fungus diseases. They will also attack the

larger wood that has been pruned

from trees, at least until it has dried

out thoroughly. They seem to be

particularly attracted to the souring

sap, but under some conditions they

will attack healthy wood. The

beetles, which are about one-tenth

inch long, bore into the sapwood

and make tunnels through it, in

which they lay their eggs. The

souring sap favors the growth of

a fungus, and the young grubs feed

on this as well as on the wood.

There are two or more broods a

year.

In the fall the grubs of the last

summer brood transform to beetles,

which remain in thé tunnels until

spring, when they emerge and construct fresh tunnels. If the tunnels are numerous, the growth of

FIGURE 46.—Trunk of young tree injured

by shot-hole borers.

the trees may be affected seriously.

The beetle sometimes attacks the

heartwood also. On healthy trees

the attack often takes place just below a bud, which is weakened and

killed, even though the beetle may

be repelled by a flow of sap before

it has been able to deposit eggs. To

prevent attacks of this beetle, the

trees should be kept in a healthy,

vigorous condition. If they are

imhealthy, the cause should be determined and corrected if possible.

Lygus Bugs

Type of Injury.—Lygus bugs (fig.

47) appear in the trees early in the

spring and puncture the swelling

fruit and leaf buds, sucking the sap

from them. Their presence is often

first indicated by the brownish

drops of sap exuding from these

punctures. This loss of sap causes
INSECT PESTS OF DEICIDUOUS FRUITS IN THE WEST 37

F.I. 9160 AND F.I. 5153

FIGURE 47.—Lygus bug: A, Adult (enlarged) ; B, adult on peach bud.

the buds to dry, and in the case of

fruit buds the blossoms may never

open, or, if they do, they may be

deformed. When the bugs are sufficiently numerous, the injury is

severe and the entire crop may be

lost. The degree of injury depends

not only on the number of bugs but

on the weather. Continued settled

warm weather in March or early in

April, before alfalfa and other

ground crops have developed,

causes the bugs to feed in the trees ;

cold, rainy, or windy weather atthis

time prevents extensive feeding.

Pears and Delicious apples, as well

as peaches, are susceptible to this

injury. The bugs also sometimes

feed on the young and maturing

fruit and cause dry or corky, sunken

spots. Lygus bugs occur throughout the West and are apparently

native insects.

Life History.—The adult lygus

bugs are nearly one-fourth inch

long, grayish or greenish, and with

variable markings. They come out

of hibernation during the first

warm, sunny days of early spring

and feed for a time on fruit-tree

buds and the leguminous coyer

crops. They are active, flying

readily or moving around to the opposite side of a twig or bud when

approached, and are not easily seen.

Eggs are laid in the tender shoots

or in the flower heads of several

plants. The nymphs resemble the

adults, except they are smaller and

have no wings. They feed chiefly

on cover crops and weeds. Growth

is attained in less than a month.

They go through a series of molts as

they increase in size. There are

three or four broods during the season, and the bugs are often very numerous in the fall. Many die with

the onset of cold weather, and the

mortality among those hibernating

is apparently high.

Other Sucking Bugs

Several other species of sucking

bugs feed on peaches, causing them

to develop irregularly and to become distorted. These include the

consperse stink bugs (see p. 18) and

tiie leaf-footed bugs. Tlie latter are

about three-fourths inch long, narrow, and brown, with some yellow

markings. Their long hindlegs

have flattened enlargements on them

simulating leaves, which tend to

make these bugs less conspicuous.

Feeding may occur at almost any

time during the growing season.

Western Spotted Cucumber

Beetle

The western spotted cucumber

beetle is about one-fourth inch long

and bright green. It lias 11 black

spots and a black head. These

beetles feed on various truck crops,

flowers, and ornamentals and also

eat irregular holes in green and

ripening apricots and peaches. The

yellow eggs are laid at the base of

host plants, usually truck or forage

crops, and the larvae feed on the

roots of these plants. Pupation is

in the soil. Tluis the only injury to

fruit comes from the adults. This

insect occurs chiefly in California

and Oregon.
38 AGKICXJLTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

Thrips

In California several species of

tlirips are found on apricot, but

they are not important pests. They

are usually called flower thrips because they are noticed most often in

the blossoms. They scar the younp:

fruit by feedinfj under the husks.

An invasion of tiirips into the trees

often results from the liarvesting

or diskinjî of nearby field crops or

cover crops, and the thrips are

forced to find new feeding grounds.

European Earwig

Type of Injury.—Tiie European

earwig has spread into most of the

western fruit-growing districts. It

is most often seen in the adult stage

(fig. 48). The insects hide under

leaves and trash during the day and

feed mostly at night. They often

climb into fruit trees, particularly

apricot and peach, and feed on the

foliage and ripening fruit. Injury

to the latter is in the form of irregular pits, usually shallow but

sometimes deep.

TÂfe History.—The adults are

slender, shining brown insects,

two-thirds inch long, with a pair

of conspicuous forceps on the posterior end. They winter in the soil,

where tlie females dej^osit eggs. The

young earwigs, or nymphs, emerge

in April or May and develop in the

open. They are gregarious. Often

they are found liiding in considerable numbers under boards or loose

bark or in crevices on tree trunks.

Wlien disturbed they move alx)ut

rapidly looking for new hiding

places.

Stone Fly

Stone flies or salmon flies occasionally injure tlie buds of peach,

apricot, and plum trees in the spring

(fig. 49), particularly in the Northwest, where tliese trees are growing

near the Columbia River or some

other large stream. The young of

these insects live in the streams. Tlie

adult flies emerge early in the

spring, when thousands of cast skins

may be found among the rocks along

the streambaiiks. The flies feed on

the fruit buds mostly during warm,

sunny weather, destroying many of

the buds and injuring othei-s so that

they produce deformed fruit.

r.I. 4905

FiGUEE 48.—Adults of European earwig.

FIGURE 49.—Stone fly feeding on peach

buds.

CHERRY INSEaS

San Jose Scale

The San Jose scale is not often

very injurious to sour cherries, but

it does a great deal of damage to

sweet cherries. As these trees usually grow large, the tops are difficult

to spray thoroughly, and dead

leaves are commonly seen clinging

to the upper branches of large sweet
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 39

cherry trees durinj^ the winter.

This is an almost sure indication

tliat these brandies are infested

with the scale. For information on

the life history and habits of this

pest, see page .3.

Cherry Fruit Flies

The cherry fruit fly and the black

cherry fruit fly (fig. 50) attack cultivated cherries. The latter is

chiefly injurious in Montana, although it occure elsewhere in the

West. The former species is most

often found in Washington and

Oregon and in some parts of Idaho.

Both species also live in the bitter

cherry (Prunus emarginata). In

California they infest the fruit of

this wild cherry in the mountains,

but are not found in commercial

orchards.

F.I. 9964A AND F.I. 9964B

P^OURE 50.—Wings of cherry fruit fly

(A) and black cherry fruit fly (B)

(enlarged).

Type of Injury.—Injury is especially severe in years when the

cherry crop matures late, since a

late season apparently delays the

fruit more than it delays the flies

and gives them the opportunity to

infest the main crop of cherries.

In normal years the maggots live

chiefly in seedlings and late varieties. The young maggots begin to

feed about the cherry pit, and the

flesh of an infested cherry may be

separated from the pit very easily ;

this separation cannot be done with

an uninfested cherry. Feeding

may occur before there are any outward signs of infestation and often

before the maggots are large

enough to be seen easily. Later on

the cherry begins to shrivel on one

side, the flesh is more or less decayed,

and small holes appear in the skin.

At this stage the white, nearly fullgrown maggot may readily be

found in the fruit. Usually there

is only one, but sometimes two or

more. , Tlie maggots are more easily seen in the dark-meated varieties of cherries, such as the I^ambert

and the Late Duke, and give the

impression that white cherries are

not seriously infested. However,

careful examination shows that the

white cherries are often infested

just as much as the black ones. The

infestation in unsprayed trees at

times amounts to 75-90 percent of

the crop.

Life History.—The maggots

overwinter in the soil in small, hard

brown cases, or puparia. These are

produced by the shrinking and drying of the outer skin of the maggot.

The flies (fig. 51) emerge from the

ground during June or July and

fly about in the sun for some days,

feeding on any moisture or honeydew on the trees. After a few days

the females lay eggs in the cherries,

piercing the skin of the fruit with

their ovipositors and depositing the

eggß in the flesh. The very small

white maggots hatch in a week or

less and immediately begin to feed

«i^^

^

•.^ ?

k^

P.I. 9965

FIGURE 51.—Cherry fruit flies.
40 AGRICULTURE HANDBOOK 3 06, U.S. DEPT. OF AGRICULTUREi

about the pit. Feeding continues

for about 2 weeks. When fully

grown the maggots, which are about

one-fourth inch long, drop to the

ground and form their puparia a

few inches beneath the surface.

They remain there until the following spring.

Orchard Mites

On cherry trees the McDaniel

spider mite and the yellow spider

mite are usually more injurious

than other mite species. They hibernate beneath the fallen leaves or

in other trash and migrate into the

trees in the spring assoon as the new

leaves appear. They are not often

seen before June, and do their most

serious injury after the fruit has

been picked. Cherry trees are frequently neglected at this time and

allowed to become dry. This condition aggravates the injury caused

by the mites and may very materially reduce the succeeding year's

crop by weakening the fruit buds.

If cherry trees appear dry and

dusty during the late summer, mites

may be suspected on the trees.

Closer examination will reveal the

webbing, in which the small greenish or yellowish mites are running

about. For more complete descriptions of these and other red spiders,

see page 9.

Plum Rust Mite

The plimi rustmite, or cherry rast

mite, causes browning or bronzing

and sometimes curling of the leaves.

It feeds mostly on the uppersurface,

where it is not easily seen even with

a hand lens. Itis much smaller than

spider mites. The plum rust mites

overwinter under the bud scales,

mostly in the adult stage. They are

whitish and somewhat triangular.

They occur on cherry, plum, and

prune trees.

Black Cherry Aphid

Type of Injm^.—The black

cherry aphid is large, shiny, and

black. It occurs on the young foliage of cherry trees and often interferes with the terminal growth. It

is found much more often on sweet

than on sour cherry trees and is particularly injurious to young trees

and to nursery stock. The leaves of

infested trees are severely curled

(fig. 52) and covered with a sticky

honeydew. This aph'd is a European species that has become prevalent in the United States.

Life History.—The winter eggs,

which are tucked in among the buds,

hatch about the time the buds burst.

The young develop rapidly on the

new growth, curling the leaves and

feeding within the protection thus

afforded. There are several generations a year. Winged aduUs develop in the middle of the summer

and migrate to watercress, pepperFiGURE 52.—Cherry foliage injured by

black cherry aphid.
MSEiCT PE^^S OF DEICIDUOÜS FRUITS IN THE WEIST 41

grass, and other plants of the mustard family. A later generation returns to the cherry in the fall and

produces wingless individuals that

lay the overwintering eggs.

Leafhoppers

Type of Injury.—The Western

X-disease virus is transmitted in

cherry by the geminate leafhopper

and by several other species. These

insects live normally in alfalfa, but

they also feed on fruit trees, and

thus may carry the virus from diseased to healthy trees. The disease

is not of great importance, but if

individual trees become seriously affected, they should be removed.

Life History.—These leafhoppers

overwinter as eggs, which have been

inserted into leaves of cherry or into

the leaves and stems of alfalfa or

other field crops. The eggs hatch in

the spring, and there may be two

or more generations a year. For

more information on leafhoppers,

see page 16.

Pear-Slug

The pear-slug, sometimes called

the cherry slug, frequently skeletonizes the leaves of cherry trees. If it

is not controlled, the trees may be

almost completely defoliated, as the

skeletonized leaves die and drop off.

This condition seriously affects the

development of fruit buds for the

following year's crop. The life history of this pest is given on page 24.

Cherry Fruitworm

Type of Injury.—The cherry

fruitworm is the larva of a small

moth found in many parts of the

United States. It is a native insect

that originally lived on wild cherry.

The larvae bore into the green cherries and feed about the pit. Injured

cherries are often misshapen.

Life History.—The cherry fruitworms winter as full-grown larvae

in the stubs of pruned branches or

in cells cut into the corky bark. The

small gray moths appear in May or

early June and deposit eggs singly

on the cherries, usually in the suture

or at the stem end. The eggs are

opalescent, circular, flattened, and

smaller than the eggs of the codling

moth. They hatch in about 10 days,

and the larvae immediately bore

into the fruit. The pinkish larvae

are three-eighths inch long and mature in about 3 weeks. There is only

one brood a year.

Destructive Pruneworm

The destructive pruneworm is

sometimes a pest of cherries, particularly in Oregon. For further information, see page 48.

Pandemis Moth

Type of Injury.—The pandemis

moth has been present in the West

for many years, but only occasionally does it become a pest. It is

similar in appearance and habits to

the fruit-tree leaf roller (see p. 32).

The caterpillars feed on apple, apricot, cherry, plum, and prune, but

apparently not on peach. The small

larvae feed on tender foliage at the

tip of branches or along the midrib

of leaves and develop slowly. Later

they feed on the fruit. On cherries

they are most often found feeding

about the stem end, and some of

them may burrow into the fruit. On

apricots a single larva may feed on

all fruits in a cluster, making large

holes in the sides. Feeding on

plums and apples is similar. In

California they sometimes feed on

the buds during the winter.

Life History.—There are two

broods of this insect a year. It

winters as a small larva hiding in

trash or in a web constructed on the

tree trunk at the ground surface.

The larvae crawl up the trees in the
42 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

spring, as soon as the leaves are out,

and feed on the foliage. They mature in May, spinning loose cocoons

in the leaves. The moths appear in

late May and in June. The lightgreen eggs are deposited in flat

clusters of 90 to 150 on the smooth

upper surface of the leaves (fig. 53),

and they hatch in about 2 weeks.

The larva may be distinguished

from cherry fruit fly maggots because it is greenish and has a definite

head and legs. The second brood

matures late in July or August.

Moths from this brood are flying in

August and September, and the

young larvae coming from their

eggs feed until cold weather and

then hibernate.

Syneta Leaf Beetle

Type of Injury.—The syneta leaf

beetle, a common pest of cherry,

ranges from northern California to

British Columbia. It is most injurious in western Oregon and

Washington. It is a native insect

that frequents cultivated orchards,

where it feeds on apple, pear, plum,

prune, small fruits, and some nut

trees as well as cherry. The beetles

eat the skin and flesh of the immature fruit (fig. 54). This injury

causes scars and deformities on the

mature fruit. The beetles also feed

on the stems, causing some of the

fruit to drop, and on the buds, blossoms, and leaves.

Life History.—The beetles emerge

from the ground just before the

trees begin to bloom. They are

about one-fourth inch long and

light gray or yellowish (fig. 55).

They begm feeding in the trees at

once and may be found in the

orchards for about 2 months. They

remain between the buds or among

the foliage, but fly out in warm

PioTJEE 53.—Egg masses of pandemls

moth.

FIGURE 54.—Immature cherries injured by

syneta leaf beetle.
INSECT PESTS OF DECIDUOUS FRUITS IN THE «VEST 43

FIGURE 55.—Male and female of syneta

leaf beetle.

weather if the trees are shaken or

sprayed. Eggs are simply dropped

to tlie ground, where tliey are very

difficult to find because they are so

small. The eggs hatch in 2 or 3

weeks, usually just after a rain or in

damp weather, as the young grubs

find it difficult to survive in dry soil.

The grubs burrow into the ground,

where they feed on the fine fibrous

roots cf the trees and in this way

do a certain amount of damage.

Feeding continues throughout the

summer and fall. The grubs remain

in the soil during the winter, forming small cells early in the spring

Within these cells they change to

pupae and then to beetles.

Pear Thrips

The pear thrips is sometimes injurious to cherries. Its habits are

much the same as on prune trees

(seep. 46).

Shot-Hole Borers

Cherry trees are sometimes attacked by one of the shot-hole

borers. They make small round

holes in the trunks or small limbs.

At times these insects attack healthy

trees, boring into the twigs just beneath the buds and killing the buds.

For more information on these insects and their habits, see page 35.

Rain Beetles

In Wasco (^ounty, Oreg., a species

of rain beetles attacks the roots of

cherry. Its appearance and habits

are similar to those injuring apple

and ]>ear (see p. 27). Allied sjiecies

are occasionally found on cherry

roots in other parts of the Pacific

States.

Other Root-Feeding Grubs

The grubs of the ten-lined June

beetle and of the California prionus

will occasionally be found feeding

on the roots of cherry. The former

are 1 to 2 inches long and the latter

may reach a length of 3 inches.

They are somewhat similar in appearance to the grubs of the ram

beetles. However, the adults are

diiïerent. The June beetle is a little

more than an inch long and brown

with whitish stripes, and the prionus

is 11/^ to 2 inches long and uniformly dark brown.

PRUNE AND PLUM INSECTS

European Fruit Lecanium

Type of Injury.—The European

fruit lecanium is found throughout

the West wherever deciduous fruit

is grown. Injury from this scale

results in reduced tree vigor. More

direct injury is caused by the quantities of honeydew secreted by the

scales. This drips down over the

fruit and foliage, and a black fungus grows in it, greatly depreciating

the appearance of the fruit.

Life History.—This is a large,

hemispherical, more or less

wrinkled, brown scale insect, oneeighth to one-fourth inch in diameter. It lives on the twigs and

limbs of deciduous fruit trees and

also on many sliade trees (fig. 56).

It winters as a nearly mature insect,

laying eggs beneath the shell in the
AGRICULTURE HANDBOOK 3 06, U.S. DEPT. OF AGRICULTURE

(see p. 5), and the Italian pear

scale (see p. 5).

Aphids

Type of Injury.—Four or five

species of aph'ids occur on prunes

and plums in the West. Habits and

injury are similar for all of these

species. Tlieir feeding causes splittmg of fruit, curling of leaves, and

stunting of growth. The discharge

of honeydew also injures the tree

and fruit.

One of the commonest species is

the hop apliid, wliich is a serious

pest of hops but spends a part of the

year on prune trees. Planting hops

near prune orchards should therefore be avoided if possible. This

green aphid often covers the undersurface of the leaves of prune trees

early in the season. The niealy

plum aphid is bluish green, witli a

whitish, powdery covering (fig.

57). It frequently becomes exceedingly abundant on the undersurface

of leaves. The thistle aphid, the

leaf-curling plum aphid, and the

green peach aphid also occur on

prune and plum trees and occasionally become abundant. These

aphids are green or reddish, and

they curl the leaves considerably.

All these species originated in Europe.

Life History.—The life histories

of these aphids are similar. Wintering eggs are laid on the trees and

hatch early in the spring before the

buds have swelled appreciably.

The young feed within the opening

buds and on the leaves. After several generations have developed on

the prune trees, winged forms develop and fly to the summer host

plants, and later generations return

to the trees in the fall. During the

summer the hop aphid is found on

hops, the mealy plum aphid on reed

grasses and cattails, the thistle

aphid on thistles, chrysanthemums.

FIGURE 56.—European fruit lecanium : A,

Adult; B, Immature stage. (Courtesy

California Agricultural Experiment

Station. )

spring. The eggs hatch from May

to July, and the yoimg settle on the

twigs and leaves. In the fall before

the leaves drop, those that have survived on them migrate back to the

twigs. There is only one generation

a year.

San Jose Scale

The San Jose scale is an important pest of prune and plum. For

furtiier information, see page 3.

Other Scale Insects

In California several other scale

insects infest prune and plum.

These include the black scale (see

p. 34), the brown soft scale, which

has similar habits, the olive scale
INSECT PESTS OF DECIDUOUS FRUITS IN THE "WEST 45

FIGURE 57.—Mealy plum aphids on plum

foliage.

and other plants, and the other

species on a large variety of wild

and cultivated plants.

Orchard Mites

Prune and plum trees are often

seriously affected by red spiders.

The foliage is bronzed and defoliation may occur in nonirrigated

orchards, frequently accompanied

by dropping of some of the fruit.

InjuryIby the mites may prevent the

fruit buds from forming or at least

may weaken them, causing a small

crop or small fruit the following

year. This injury is often much

more serious than is apparent. The

species most commonly found on

these trees are the brown mite, the

European red mite, the McDaniel

spider mite, the two-spotted spider

mite, and the Pacific spider mite.

For further information on these

mites, see pages 9, 29, and 40.

Plum Rust Mite

Injury by this mite to prune and

plum is similar to that on cherry

(seep. 40).

Leafhoppers

Leafhoppers often become numerous on prune trees. Some of

these may be the same species found

on apple (see p. 17). In the

Yakima Valley and perhaps elsewhere anotlier species, Typhlocyha

jyrunicola Edwards, occurs on

prune.

Peach Twig Borer

Prune trees are attacked by the

peach twig borer in much the same

manner as are peach trees. The

brown worms bore into the tender

new growth, causing leaves to wilt,

and later they feed in the fruit.

The life history of this pest is given

on page 30.

Peach Tree Borer

The peach tree borer is chiefly injurious to peach in California, but

in other parts of the West it may do

more harm to prune trees than to

peach trees. For a discussion of

this insect, see page 35.

Other Borers

The California prionus (see p. 43)

attacks prune and plum in California. The American plum borer

may be found attacking these trees

in both California and Oregon.

The latter is the larva of a small,

obscurely colored moth, which

emerges in May and June. The

larvae, or borers, make winding burrows in the sapwood, causing dead

areas to appear in the bark. When
46 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

full grown they are about an inch

long. There are two broods. The

larvae of the second brood mature

in November. This pest usually

attacks only trees in poor condition.

The branch and twig borer attacks prune and sometimes apricot

and pear in California and Oregon.

It bores into the twigs and smaller

branches, often at the axil of a bud

or where two branches fork. The

beetle is about one-half inch long,

slender, brown, and with a round

head. The early stages do not live

in fruit trees.

The shot-hole borers attack unhealthy deciduous fruit trees, making round holes in the trunks (see

p. 35). The flatheaded apple tree

borer may also at times be found in

the trunks of such trees (see p. 26).

Pear Thrips

Type of Injury.—The pear thrips

probably causes more injury to

?rune in the West than to other

ruits. This pest was apparently

introduced from Europe. There

are three types of injury. The

most serious is caused by the adult

thrips, which emerge from the

ground in the spring. They feed

m the developing buds, cause deformed leaves and blossoms (fig.

58), and thus reduce the crop.

Later the adults lay eggs in the

stems of the fruit and foliage.

Both the young and the adults feed

by rasping the surface and then

sucking out the plant juices.

Life Hittory.—There is only one

generation of the pear thrips annually. The adults are small, less

tlian one-twentieth inch long, slim,

and dark brown. They emerge

when the fruit buds are swelling and

beginning to show green. After

feeding for about 3 weeks, they begin egg laying, which lasts another

3 weeks. The very small, whitish,

FIGURE 58.—Prune twigs showing deformed leaves and poor set of fruit

caused by pear thrips.

kidney-shaped eggs hatch in less

tliaii 2 weeks. The young are white

and similar to the adults in shape

(fig. 59). Tliey develop for about

3 weeks, then drop to the ground,

burrow into the soil, and construct

small cells a few inches to 3 feet

from the surface. Here they remain

dormant, changing late in the fall

to adults, which emerge the following spring. The pear thrips is thus

active on the trees for only about 2

months in the spring and is dormant

in the ground the rest of the year.
INSECT PESTS OF DECIDUOUS FRUITS IN THE WEST 47

FiouEE 59.—Pear thrlps -.A, Eggs ; B, larva ; C, pupa ; D, adult ; E, posterior end of

female showing ovipositor.

Eye-Spotted Bud Moth

The eye-spotted bud moth is a

cool-climate insect, occurring in

British Columbia, Montana, northem Idaho, western Washington and

Oregon, and in some parts of California. Itis also a pest in the Eastern States and in Europe, which was

its original home.

Type of Injury.—This insect

damages prunes and plums, but is

also found on all the orchard fruits

as well as on some other plants. It

causes most injury to the expanding

buds, which are devoured by the

partly grown, hungry caterpillars

that have hibernated on the trees.

Crops are reduced by its bud-feeding habit, and injury to the terminal

shoots causes a bushy growth (fig.

60). Later the insects eat the foliage, and a new generation feeds on

the fruit, often attaching a leaf to

it and feeding in the shelter thus

formed.

Life History.—The partly grown

dark-brown larvae of this bud moth

winter in small silken nests, or hibernacula, attached to the twigs,

often in a crevice or crotch. These

nests are made of pieces of leaves or

bark held together with silk and are

difficult to find on the trees. The

larvae leave them in April, or whenever the buds begin to swell appreciably, and burrow into the expanding buds and into the terminal

shoots, feeding from the inside.

Nests of silk are formed in thé opening leaves. As the foliage surrounding them dries, the larvae go

outside to eat leaves or blossoms, retiring to the nests when not feeding.

These webbed nests are often the

first indication of the presence of

the insects. The larvae become full

grown in June or early July, when

they are olive brown with black

heads.

They transform to pupae in the

nests of webbed leaves, and the

moths appear about 3 weeks later.

These are somewhat smaller than

codling moths, ashy gray, and with

a cream-white band across both
48 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRIOULTURE

FIGURE 60.^Bushy terminal growth of

prune caused by larvae of eye-spotted

bud moth.

F.I. 5810

FIGURE 61.—Eye-spotted bud moth.

wings (fig. 61). The flattened

eggs, similar to those of the codling

moth, are deposited on the leaves

and hatch in a week or so. The

young larvae feed on the leaves,

protecting themselves with silk, and

often eat small holes in the fruit.

In the fall these larvae build the

hibernacula in which they spend the

winter. There is only one generation a year.

Lesser Appleworm

The lesser appleworm occasionally injures prunes in eastern Oregon and southern Idaho. It also

occurs in British Columbia, and is

known as a serious pest of apple in

sections of the Eastern United

States and Canada. The egg,

larva, and adult moth are somewhat

similar in appearance to the corresponding stages of the codling moth,

except that they are smaller (see

p. 1). The habits of the insect

are also similar.

Destructive Pruneworm

The destructive pruneworm has

become a rather serious pest of

prune and cherry trees in southern

Idaho and in parts of Oregon. Its

habits are somewhat like those of

the eye-spotted bud moth. The

partly grown brown worms winter

in small hibernacula woven of silk

and placed in the smaller crotches

or in crevices in the bark. These

worms emerge in the spring before

the flower buds are open and bore

into the buds, feeding entirely on

the inside and destroying many

blossoms. They become full grown

in 2 to 4 weeks, when they drop to

the ground and spin loose cocoons.

The moths emerge from these cocoons in Jime and lay eggs singly

on the lower surface of the leaves.

The worms hatching from these

eggs burrow into the green prunes

or cherries and cause considerable

injury by feeding on the fruit.

This second brood of worms becomes full grown late in July or

early in August and produces a second brood of moths. Worms com-
INSECT PESTS OF DECIDUOUS FRUITS IN THE "WEIST 49

ing from eggs laid by these moths

feed for a time in the maturing

i)runes or on the foliage and then

eave them and spin the silken nests

in which they hibernate. There are

thus two complete generations a

season.

Snowy Tree Cricket

Type of Injury.—-Th.^ snowy tree

cricket occurs throughout the

Northwest, but has been of economic importance chiefly in southem Idaho, where it sometimes does

considerable harm to prunes by eating holes in the ripening fruit.

Much of the injured fruit drops

prematurely and the remainder is

unfit for market. Early in the season the young feed on the foliage,

but this injury is of little consequence.

Life History.—Tlie adult crickets

are slightly more than one-half

inch long and light green or yellowish. The females (fig. 62) have narrow, transparent wings, and the

males have somewhat broader

wings. There is but one generation

a year, and the adults may be found

in the orchards from July until

frost occurs.

Leaf-Cutting Bees

Sometimes large round holes may

be found in tlie leaves of prune and

plum trees. These are usually

caused by the small brown, metallic

green, or blue leaf-cutting bees.

Tlie nests of these bees are built in

holes in the ground, in hollow stems

of plants, or holes bored in wood.

The nests may usually be found not

far from the injured trees. Tlie

bees cut circular or oblong disks

from the leaves and use them to line

tlie nests in wliich eggs are laid and

where the young develop. Injury

FIGURE 62.—Female of snowy tree cricket

(enlarged) and section of twig showing

egg.

to trees is usually not serious.

Since the bees are also beneficial as

pollinating insects, no measures

should be taken against them unless

the injury is extreme.

Syneta Leaf Beetle

The syneta leaf beetle ordinarily

does not injure prunes as severely

as it damages pears and cherries

(pp. 25 and 42). Most of the prunes

grown in the area where this beetle

occurs are sold in the dried form,

and the smaller injuries are of less

consequence than those on fruit that

is to be marketed green or fresh.

Large russeted areas on the prunes

detract from the appearance of the
50 AGRICULTURE HANDBOOK 306, U.S. DEPT. OF AGRICULTURE

dried product (fig. 63) and make

the fresh fruit unmarketable.

Western Spotted Cucumber

Beetle

The western spotted cucumber

beetle sometimes injures prunes in

the same manner that it does apricots and peaches. For information

about this beetle, see page 37.

Caterpillars

Several caterpillars may attimes

be found on prune trees. They include tent caterpillars (see p. 20),

fall webworms (see p. 20), tussock

moths (see p. 21), and red-humped

caterpillars (see p. 21).

Stink Bugs

Several stink bugs may be found

on prune (see p. 18).

F.I. 4880

FIGURE 63.—Dried prunes : Above, russeted by syneta leaf beetle ; below,

uninjured.

BENEFICIAL INSECTS

Not all insects found in an

orchard are harmful. Many are of

no importance because they are not

sufficiently numerous or do not inSre the trees or the cover crop,

any others are beneficial because

they feed on some of the insects that

are harmful to the crops. The most

conspicuous beneficial insects and

the ones most often found in an

orchard are those that prey on

aphids.

Lady beetles are nearly always

abundant in orchards, and their

young feed on the aphids in cover

crops or on trees. There are many

species. One of the commonest is

the convergent lady beetle (fig. 64),

which is red with black head and

black spots on the back. Some species are plain red, others are black

witli two or more red spots. There

are also small black lady beetles

(fig. 65) tliat feed chiefly on orchard

mites and scale insects. Most of

these species lay yellow or orange

cigar-shaped eggs, which stand on

end in clusters. The larvae are usually black or gray, with various red

or orange markings. Some of them

are covered with a white waxy secretion, giving them the appearance of

mealybugs. Although most of the

lady beetles are conspicuous, t^hey

are not molested by birds, possibly

because of a disagreeable taste.

The larvae of syrphid flies are

very common enemies of aphids and

are most often found in colonies of

the woolly apple aphid. Frequently

they destroy the colonies entirely.

These larvae or maggots (fig. 66)

are nearly one-half inch long when

full grown, yellowish or grayish,

and often with a stripe down the

back. The posterior end of the body

is widest, and the narrow liead is

restlessly moved about as the maggot searches for food. No legs are

evident. The adult syrpliid flies are

usually black, striped with yellow,

and may be mistaken for wasps or
INSECT PESTS OF DECIDUOUS FRUITS ENT THE WEST 51

TC-2202

FIGURE 64.—CJonvergent lady beetle: A, Adult; B, pupa; C, larva. (Enlarged.)

P.I. 982,-)

FIGURE 65.—Small black lady beetle

(enlarged).

bee.s. They fly rapidly and often

poise in midair before darting down

to a colony of aphids to deposit their

grayish elongated eggs. The eggs

are laid singly among the aphids.

The young of lacewing flies (fig.

FIGURE (56.—Larva of syrphid fly (enlarged ).

67) are effective enemies of aphids

and also feed on other insects such

as newly hatched codling moth larvae and the young of leafhoppers.

The lacewing fly larvae, known as

ai)hid lions, are flat, elongated,

tapering at both ends, and with long

legs and conspicuous sickle-shaped
52 AGRICULTURE HANDBOOK 3 06, U.S. DEPT. OF AGRICULTURE.

V ^'. F

FIGURE 67.—Lacewing fly: A, Eggs; B, larva; C, foot; D, larva feeding on psylla; E,

empty pupa; F, adult; G, head of adult; H, adult. (All enlarged except H.)

jaws. When mature they are about

three-eiffhths inch long, grayish or

yellowish, and with red or brown

markings. They spin spherical

white cocoons, from which the

adults escape by cutting circular

lids. The adults are light green

with delicate transparent wings and

golden eyes. They emit a very disagreeable odor when crushed, and

this doubtless protects them from

birds and other enemies in the same

manner as lady beetles are protected.

The eggs are deposited in clusters,

each egg on a long stalk (fig. 67).

This characteristic is believed to

Erêvent the eggs from being eaten

y the young or by other insects.

There are also many predaceous

bugs and beetles that prey on various insects, as well as small predaceous mites and thrips that feed

on orchard mites. In addition to

these, there are hosts of small inconspicuous parasitic insects, mostly related to the bees and wasps,

that take their toll of the pests. One

of these, Aphelinus mali (Haldeman), a parasite of the woolly apple aphid, has been introduced into

the Pacific Northwest.

It is difficult to estimate the benefit from predaceous and parasitic

insects. The beneficial species prevent many potentially harmful insects from becoming numerous, and

therefore should be promoted in

every way. Frequently, also, outbreaks of serious pests are checked

more completely by beneficial insects than is possible with artificial

control measures. Unfortunately

the beneficial forms often are not

effective until after the harmful

species have done much damage, and

the fruit grower cannot afford to

wait but must control the pests himself. The sprays applied to trees,

particularly the contact sprays,

destroy many of the beneficial m-
INlSEiCT PESrrS OF DECIDUOUS FRUITS IN THE WEIST 53

sects. Some of these insects, such seriously reduced in numbers. Howas the syrphid flies and the lady ever, some of them may increase late

beetles, withstand insecticides fairly in the season afterspraying has been

well, but the smaller ones are often discontinued.

LIST OF ORCHARD INSECTS

Common name Scientific name

American plum borer Euzophera semifuneralis (Walker)

Apple-and-thom skeletonizer Anthophila pariana (Clerck)

Apple aphid Aphis pomi DeGeer

Apple fruit miner Marmara pomonella Busck

Apple grain aphid Rhopalosiphum fitchii (Sanderson)

Apple lacebug^ Corythucha salicata Gibson

Apple leafhopper Empoasca maligna (Walsh)

Apple leaf miner ^ Lithooolletis crataegella Clemens

Apple leaf trumpet miner Tischeria malifoliella Clemens

Apple rust mite Aculus schlechtendali (Nalepa)

Bailey's apple rust mite ^ Calepitrimerus haileyi Koch

Bean aphid Aphis falae Scopoli

Bean thrips Caliothrips fasciatus (Pergande)

Black cherry aphid Myzus oerasi (F.)

Black cherry fruit fly Rhagoletis fausta (Osten Sacken)

Black peach aphid Brachycaudus persicaecola (Boisduval)

Black scale Saissetia oleae (Bernard)

Boxelder bug Leptoooris trivittatus (Say)

Branch and twig borer ^ Polycaon confertUrS LeConte

Bronze apple tree weevil Magdalis aenescens LreConte

Brown mite^ BryoMa rul)rioculus (Scheuten)

Brown soft scale Coccus hesperidum L.

Buffalo treehopper Stictocephala huhalus (F.)

Calico scale Lecanium cerasorum Cockerell

California pear-slug Pristiphora ahhreviata (Hartig)

California prionus Prionus califomicus Motschulsky

Cankerworms ^ Geometridae

Cherry fruit fly Rhagoletis cingulata (Loew)

Cherry fruitworm Grapholitha packardi Zeller

Climbing cutworms ^ Noctuidae

Codling moth Carpocapsa pomonella (L.)

Consperse stink bug ^ Euschistus conspersus Uhler

Convergent lady beetle Hippodamia convergens Guérin-Méneville

Cottony maple scale Pulvinaria innumeraMUs (Rathvon)

Dark-colored treehopper ^ Ceresa hasalis Walker

Destructive pruneworm ^ Mineóla scitulella Hülst

Dock sawfly Ametastegia glabrata (Fallen)

European earwig Forfícula auricularia L.

European fruit lecanium Lecanium corni Bouché

European red mite Panonychus ulmi (Koch)

Eye-spotted bud moth Spilonota ocellana (Denis & Schiffermüller)

Fall cankerworm Alsophila pometaria (Harris)

Fall webworm Hyphantria cunea (Drury)

Flatheaded apple tree borer Chrysohothris femorata (Olivier)

Flower thrips Frankliniella tritici (Fitch)

Frosted scale ^ Lecanium pruinosum Coquillett

Fruit-tree leaf roller Archips argyrospilus (Walker)

Geminate leafhopper^ Colladonus geminatus (Van Duzee)

Grape mealybug Pseudococcus maritimus (Ehrhorn)

Green clover treehopper ^ Stictocephala inermis (F.)

Green fruitworms^ : Noctuidae

Green peach aphid Myzus persicae (Sulzer)

Hop aphid Phorodon humuli (Schrank)

Howard scale Abgrallaspis howardi ( Cockerell )

Italian pear scale Epidiaspis piricola (DelGuereio)

Lacewing fly^ Chrysopidae

See footnotes at end of table.
54 AGBICTJLTITRE HAJSTDBOOK 306, U.S. DEPT. OF AGBICULTÜRB

LIST OF ORCHARD INSEaS—Continued

Common name Scientific name

Leaf-curling plum aphid ^ Anuraphis helichrysi (Kaltenbach)

Leaf-cutting bees ^ Megachile spp., Osmia pellax Sandhouse

Leaf-footed bug Leptoglossus phyllopus (L.)

Lesser appleworm GraphoUtha prunivora (Walsh)

Lygus bugs ^ Lygus hesperus Knight, L. elisus Van Duzee

McDaniel spider mite ^ Tetranychus mcdanieli McGregor

Mealy plum aphid— Hyalopterus pruni (Geoffroy)

Measuring worms ^ Geometridae

Melon aphid Aphis gossypii Glover

Oblique-banded leaf roller Choristoneura rosaceana (Harris)

Olive scale Parlatoria oleae (Colvee)

Orange tortrix Argyrotaenia citrana (Femald)

Orchard mites ^ Tetranychidae

Oriental fruit moth GraphoUtha molesta (Busck)

Oystershell scale Lepidosaphes ulmi (L.)

Pacific flatheaded borer Chrysohothris mali Horn

Pacific spider mite Tetranychtis pacifious McGregor

Pandemis moth ^ Pandemis atbaniana Walker

Peach silver mite Aoulus comutiis (Banks)

Peach tree borers Sarminoidea emtiosa (Say), S. exitiosa

graefi (Hy. Edwards)

Peach twig borer Anarsia lineatella Zeller

Pear leaf blister mite Eriophyes pyri (Pagenstecher)

Pear psylla Psylla pyricola Foerster

Pear rust mite Epitrimerus pyri (Nalepa)

Pear-slug Galiroa cerasi (L.)

Pear thrips Taeniothrips inconsequens (Uzel)

Plum rust mite Aculus fockeui (Nalepa & Trouessart)

Putnam scale Aspidiotus ancylus (Putnam)

Rain beetles^ Pleocoma minor Linsley, P. crinita Linsley,

P. oregonensis Leach

Red-humped caterpillar Schizura concinna (J. E. Smith)

Red spiders ^ Tetranychidae

Rose leafhopper Edwardsiana rosae (L.)

Rosy apple aphid Dysaphis plantaginea (Passerini)

Rusty tussock moth Orgyia antiqua (L.)

Salmon fly ^ Plecoptera

San Jose scale Aspidiotus pernioiosus Comstock

Shot-hole borers Scolytus rugulosus (B^sitzehuxg), Anisandrus

pyri (Peck)

Snowy tree cricket Oecanthus fultoni T. J. Walker

Spotted cutworms Amathes c-nigrum (L.), Ahagrotis hamesi

(Benjamin), Euxoa spp.

Spring cankerworm Paleacrita vernata (Peck)

Stone fly ^ Taeniopteryx pacifica Banks

Syneta leaf beetle ^ Syneta albida LeConte

Syrphid fly^ Syrphidae

Ten-lined June beetle Polyphylla decemUneata (Say)

Tent caterpillars ^ Malacosoma spp.

Tentiform leaf miner ^ Lithocolletis sp.

Thistle aphid Brachycaudus cardui (IJ.)

Tussock moth^ Lymantriidae

Two-spotted spider mite Tetranychus urticae (Koch)

Western spotted cucumber beetle Diahrotica undecimpunctata undeoimpunctata Mannerheim

Western tussock moth Hemerocampa vetusta (Boisduval)

Woolly apple aphid EriosowM lanigerum (Hausmann)

Woolly pear aphid Eriosoma pyricola Baker & Davidson

Yellow-necked caterpillar Datana ministra (Drury)

Yellow spider mite Eotetranyohus carpini horealis (Ewing)

^Name does not appear in list of Common Names of Insects approved by the

Entomological Society of America.
INDEX

Page

American plum borer 27, 45

Ants 28

Aphid—

apple 14

apple grain 15

bean 15

black cherry 40

black peach 29

green peach 15, 28, 44

hop 44

leaf-curling plum 44

lions 51

mealy plum 29, 44

melon 15

rosy apple 14

thistle 44

woolly apple 13

woolly pear 15

Apple—

and-thorn skeletonizer 24

aphid 14

aphid, rosy 14

aphid, woolly 13

fruit miner 22

grain aphid 15

insects 1

lacebug 18

leafhopper 17

leaf miner 22

leaf trumpet miner 24

rust mites 12

tree borers, flatheaded 26

tree weevil, bronze 27

worm, lesser 48

Apricot insects 28

Bean aphid 15

Bean thrips 16

Bees, leaf-cutting 49

Beetle—

lady 50

rain 27, 43

syneta leaf 25,42,49

ten-lined June 43

Western spotted cucumber 37, 50

Beneficial insects 50

Black cherry aphid 40

Black cherry fruit fly 39

Black peach aphid 29

Black scale 34, 44

Blister mite, pear leaf 11

Borer—

American plum 27,45

branch and twig 46

California prionus 43, 45

flatheaded apple tree 26, 46

Pacific flatheaded 26

peach tree 35, 45

peach twig 30,45

shot-hole 27, 35, 43, 46

Page

Boxelder bug 18

Branch and twig borer 46

Bronze apple tree weevil 27

Brown mite 10

Brown soft scale 35

Bud moth, eye-spotted 24,47

Buffalo treehopper 16

Bugapple lace 18

boxelder 18

consperse stink 18, 37

grape mealy- 7,35

leaf-footed 37

lygus 18, 36

stink 50

Calico scale 6

California pear-slug 25

California prionus 43, 45

Cankerworm 22

Caterpillar—

red-humped 21,50

tent 20, 50

yellow-necked 21

Cherry—

aphid, black 40

fruit fly 39

fruitworm 41

insects 38

rust mite 40

slug 41

Climbing cutworms 24,32

Codling moth 1

Consperse stink bug 18, 37, 50

Convergent lady beetle 50

Cottony maple scale 6

Cricket, snowy tree 49

Cucumber beetle, western spotted. 37, 50

Cutworms, climbing 24,32

Dark-colored treehopper 16

Destructive pruneworm 41, 48

Dock sawfly 25

European earwig 38

European fruit lecanium 6, 35, 43

European red mite 10, 29, 45

Eye-spotted bud moth 24, 47

Fall cankerworm 22

Fall webworm 20, 50

Flatheaded apple tree borer 26, 46

Flycherry fruit 39

lacewing 51

salmon 38

stone 38

syrphid 50

Flower thrips 16, 38

Frosted scale 35

Fruit fly, cherry 39

Fruit lecanium, European 6, 35, 43

Fruit moth, oriental 30

55
56 AGRICULTURE HAJSTDBOOK 306, U.S. DEÖPT. OF AGRICULTURE

Page

Fruit-tree leaf roller 19,32

Fruitworm, cherry 41

Fruitworms, green 22, 34

Grape mealybug 7, 35

Grasshoppers 28

Green clover treehopper 16

Green fruitworms 22, 34

Green peach aphid 15, 28, 44

Hop aphid 44

Howard scale 35

Italian pear scale 5, 44

Lacebug, apple 18

Lacewing fly 51

Lady beetle—

convergent 50

small black 50

Leaf beetle, syneta 25, 42, 49

Leaf-curling plum aphid 44

Leaf-cutting bees 49

Leaf-footed bug 37

Leafhopper—

apple 17

geminate 41

rose 17

Leaf miner—

apple 22

apple leaf trumpet 24

tentiform 22

Leaf roller—

fruit-tree 19, 32

oblique-banded 19

Lecanium, European fruit 6, 35, 43

Lesser appleworm 48

Lygus bug 18, 36

Maple scale, cottony 6

McDaniel spider mite 9, 40, 45

Mealybug, grape 7, 35

Mealy plum aphid 29, 44

Melon aphid 15

Miner—

apple fruit 22

apple leaf 22

apple leaf trumpet 24

tentiform leaf 22

MiteBailey's apple rust 12

brown 10,29,45

cherry rust 40

European red 10, 29, 45

McDaniel spider 9, 40, 45

orchard 9, 29, 40, 45

Paciñc spider 10,29,45

peach silver 29

pear leaf blister 11

pear rust z 12

plum rust 40,45

two-spotted spider 10, 29, 45

yellow spider 10,40

Mothcodling 1

eye-spotted bud 24, 47

oriental fruit 30

pandemis 32,41

rusty tussock 21

western tussock 21

Page

Oblique-banded leaf roller 19

Olive scale 5, 35, 44

Orange tortrix 20, 32

Orchard mites 9, 29,40,45

Oriental fruit moth 30

Oystershell scale 5, 35

Pacific flatheaded borer 26

Pacific spider mite 10, 29, 45

Pandemis moth 32, 41

Parasites 13, 51

Peach—

aphids 28, 29

insects 28

silver mite 29

tree borer 35, 45

twig borer 30, 45

Pear—

aphid, woolly 15

insects 1

leaf blister mite 11

psylla 7

rust mite 12

slug 24, 41

thrips 15,43,46

Plum—

aphids 44

borer, American 27, 45

insects 43

rust mite 40, 45

Prionus, California 43, 45

Prune—

insects 43

worm, destructive 41,48

Psylla, pear 7

Putnam scale 35

Rain beetles 27, 43

Red-humped caterpillar 21,50

Red mite, European 10, 29, 45

Red spiders 9, 40, 45

Rose leafhopper 17

Rosy apple aphid 14

Rust mite—

Bailey's apple 12

cherry 40

pear.- 12

plum 40,45

Rusty tussock moth 21

Salmon ñy_ 38

San Jose scale 3, 34, 38, 44

Sawfly, dock 25

Scale—

black_.._ 34,35,44

brown soft 35, 44

calico 6

cottony maple 6

European fruit lecanium 6, 35, 43

frosted 35

Howard 35

Italian pear 5, 44

olive 5, 35, 44

oystershell 5, 35

Putnam 35

San Jose 3,34,38,44

Shot-hole borers 27, 35, 43, 46

Skeletonizer, apple-and-thorn 24
INISECT PESTS OF DECIDTJOUS FRUITS IN THE WEiST 57

Page

SlugCalifornia pear- 25

cherry 41

pear- 24, 41

Snowy tree cricket 49

Spider mite, two-spotted 10, 29, 45

Spotted cutworm 32

Spring cankerworm 22

Stone fly 38

Syneta leaf beetle 25, 42, 49

Syrphidfly 50

Ten-lined June beetle 43

Tent caterpillars 20, 50

Tentiform leaf miner 22

Thistle aphid 44

Thrips—

bean 16

flower 16,38

pear 15,43,46

Tree cricket, snowy 49

Treehopper—

buffalo 16

dark-colored 16

green clover 16

Page

Tussock moth 21, 34, 50

Twig borer, peach 30, 45

Two-spotted spider mite 10, 29, 45

Webworm, fall 20, 50

Weevil, bronze apple tree 27

Western—

spotted cucumber beetle 37, 50

tussock moth 21

Woolly apple aphid 13

Woolly pear aphid 15

Worm—

canker 22,34

cherry fruit 41

cut 24,32

destructive prune 41, 48

fall canker 22

fall web 20,50

green fruit 22, 34

lesser apple 48

spring canker 22

Yellow-necked caterpillar 21

Yellow spider mite 20, 40

U.S. GOVERNMENT PRINTING OFFICE: 1966 O—207-597