In this section
we describe common garden pests and how to recognize and manage
them.
Research
taken from:
 Rodale's
Chemical-Free Yard & Garden, the Ultimate Authority on Successful
Organic Gardening
Organic
Plant Protection, ed. Roger B Yepsen, Jr.
If
your pest problem does not appear here, or you want more information,
please visit these links:
Beyond
Pesticides
Click on Info Services, Alternatives Fact Sheets
Location
The European Corn Borer, discovered in Massachusetts in 1917,
has spread throughout most states east of the Rockies.
Vulnerable
plants
The corn borer eats more than just corn. It will bore into a
wide variety of plants with large stems, stalks, and fruits,
such as bell peppers, snap and lima beans, potato vines, tomatoes.
It also attacks flowers: dahlias, gladiolus, and large-stemmed
ornamental and weed plants.
Appearance
and Habits
The corn borer winters in larva form, an inch-long, flesh-colored
caterpillar with inconspicuous black dots, in old stalks left
around the garden and pupates in the same stalk. Yellow-brown
moths appear in late May or June to lay white eggs on the underside
of corn leaves over a period of 3 or 4 weeks. These eggs start
hatching about a week later, and the young larvae chew small,
round holes in leaves and move toward and into the plant stalk,
leaving behind sawdust-like excrement on the leaves and outside
the stalk. If you see bent stalks, the larvae have already done
a lot of damage inside the plant.
Management
Uprooting, shredding, and burying infected stalks is the most
successful method of destroying the corn borer because it kills
the wintering larvae. Although this method does not salvage
the affected plants, it will protect the next year's harvest.
Late plantings are
more vulnerable to the corn borer. Corn or other affected plants
should be planted early, to grow while other plants are also
bearing fruit.
Removing the borer
by hand is the oldest remedy. Split the stem a little below
the entrance hole and pick out the worm.
Other methods include
attracting the corn borer moth to light traps, or using parasitic
insects such as the ladybug, which will consume up to 60 borer
eggs a day.
Spray natural pesticide
BTK (http://gardenline.usask.ca/pests/bt.html) on undersides
of leaves and into tips of ears after silks wilt.
Pictures
European
Corn Borer (Life Cycle, page 51): A. adult moth;
B. larva, a smooth caterpillar; C. pupa and larva inside corn
stem, borer frass protruding from hole; D. female moth laying
eggs on corn leaf; E. borer working in ear of corn, with frass
protruding; F. borers overwintering in old corn stalks
Links
Penn
State College of Agricultural Sciences Department of Entomology
Location
The Corn Earworm, aka Tomato Fruit Worm, Tobacco Budworm, Cotton
Bollworm, is such a successful pest that it lives practically
everywhere in the world between the parallels of 50° north
and south latitudes. That's from the bottom half of Canada to
almost the tip of South America.
Appearance
and Habits
The earworm winters as a pupa in the soil. A brownish-olive
moth coming out in spring to lay 500 to 2500 eggs, one at a
time, on various host plants, including weeds. The eggs are
dirty white and dome-shaped. After hatching, the caterpillars
grow to nearly 2" long, have yellow heads, and vary from
yellow to brown to green with lengthwise alternating light and
dark stripes. There are several generations in a season; in
corn, first-brood larvae eat into developing leaves, while larvae
of later broods start at the silk and bore into the tip of the
ear, eating the kernels down to the cob and piling up moist
castings of excrement. In tomatoes the worms feed on the partially
ripened fruit, restlessly moving from one tomato to another;
pods of lima beans are sometimes invaded.
Management
Sweet corn is protected by applying mineral oil with a medicine
dropper into the silk at the tip of the ear. (1/2 - 3/4 of a
dropper). This should be applied after the silk turns brown.
Corn varieties with
a tightly closed ear fare better at keeping the corn borer away;
some farmers have aided the plants by attaching closepins to
the ear tips to physically block out the worms.
Other strategies
include clipping the silk every four days, and planting marigolds
near the corn.
In southern gardens,
the tomato fruit worm may be controlled by applying pinches
of bait to the fruit clusters.
Pictures
Corn
Borworm (Life Cycle, page 51): A. larvae, brown and
green striped caterpillars; B. overwintering pupa in soil; C.
female moth laying eggs on corn silk; egg enlarged; D. full-grown
worm feeding in man of frass at tip of ear
Location
The Imported Cabbage Worm came to this country from Europe,
via Quebec, arriving in Massachusetts about 1869, and quickly
spread to all parts of the United States.
Vulnerable
Plants
It attacks all members of the cabbage or mustard family (this
includes cauliflower) and also feeds on nasturtium, sweet alyssum,
mignonette and lettuce.
Appearance
and Habits
The insect winters in the pupa stage, a gray, green or tan angular
chrysalid hanging downwards from some object near the cabbage
patch. In early spring, the pupa hatches into a white butterfly
with three or four black spots on each wing, a wingspan of 1
1/2" to 2". They lay yellow, bullet-shaped eggs singly
on the undersides of leaves. In about a week, velvet-smooth
green caterpillars, with alternating light and dark longitudinal
stripes, hatch and start feeding, depositing pellets of dark
green excrement as they eat huge, ragged holes in the leaves.
They feed for 2 to 3 weeks, then pupate, there being three to
six generations in a season.
Control
Plant tomatoes, onions, garlic, and sage around cabbage to deter
the worm.
Cover plants with
a lightweight nylon net to keep the butterflies from laying
eggs.
Till the soil several
times between plantings to destroy eggs and pupa.
Hand-remove larvae.
Destroy old stalks as soon as the crop is harvested, and make
sure to destroy weeds like Wild Mustard, Pepper Grass, Shepard's
Purse, on which the first-generation worms develop.
A number of natural
enemies reduce the caterpillar population, among them common
yellow jackets and braconid wasps. Braconid wasps are attracted
by strawberries.
The cabbage worm may drown during heavy rains.
Other methods include
spooning spoiled milk into the cabbage head, or spraying with
a mixture of salt, flour, and water, which will make the caterpillars
bloat and die.
Last resorts: Spray with BTK
or sabadilla
Pictures
Cabbage
Worm (Life Cycle, page 52): A. adult butterfly; B.
full-grown worm (larva); C. egg, enlarged 10 times; D. chrysalid;
E. typical damage by worms, adults laying eggs
CABBAGE MAGGOT
Location
The Cabbage Root-Maggot, introduced from Europe almost two centuries
ago, is now a serious pest in Canada and northern United States,
but does not do much damage south of Pennsylvania. It likes
cool weather.
Vulnerable
Plants
It is injurious to cabbage, cauliflower, broccoli, radishes,
turnips and other members of the cabbage and mustard family,
and sometimes works on beets, celery and other vegetables. In
the fall months of September and October, the larvae attack
rutabagas, turnips and brussels sprouts.
Appearance
and Habits
The winter is spent as a pupa in an enclosing case (puparium),
1 to 5 ins. deep in the soil. About the time sweet cherries
bloom, and young cabbage plants are set out, a small gray fly
crawls out of the soil to lay white eggs at the base of the
stem and on adjacent soil. These hatch in 3 to 7 days into small,
white, legless maggots which enter the soil to feast on the
roots, riddling them with brown tunnels. Seedlings wilt, turn
yellow, and eventually die. After 3 weeks the maggot forms a
puparium from its larval skin and produces another fly in 12
to 18 days. The number of generations is indefinite; ordinarily
the first feeds on cabbage and its relatives, while late broods
menace fall turnips and radishes.
Control
Plant after June 1 to avoid major pest season.
Protect seedbeds
with a cheesecloth or nylon cover to prevent egg-laying, and
secure it to the ground on either side. Place a 3- to 4-in.
square of tar paper around stem of each plant set out, at ground
level.
It is sometimes possible
to remove a seedling at first sign of wilting, wash off the
maggots, and replant.
Dust red
pepper, ginger, or wood ash around the stem.
Pictures
Cabbage
Roof Maggot (Life Cycle, page 52): A. adult fly;
B. legless maggot (larva)) E. puparium in soil; C. maggots working
an roots; D. fly laying eggs at base of stem
Links
University
of Maine Pest Management Lab
GYPSY MOTH
Location
The Gypsy Moth is an expensive pest of shade, forest and fruit
trees, especially apple, elm, oaks, and aspen. Accidentally
let loose near Boston in 1869, it now inhabits an area from
the east coast to Michigan, and as far south as North Carolina.
Appearance
and Habits
The gypsy moth begins as a brown, hairy caterpillar, 2 inches
long, with 5 pairs of blue bumps along the back, followed by
6 pairs of red ones. They feed in June and July, stripping the
trees. They pupate inside a few-threads spun on limb or tree
trunk and produce moths in 17 to 18 days. The brown, yellow-marked
male flies freely, but the heavy female does not use her white
wings with their wavy dark markings. Egg clusters are white
or yellow and covered with hairs, can be as large as 1/2"
to 1" in diameter, and are found under tree branches, in
gutters, under ledges, or any other good hiding place. Distribution
is by crawling of caterpillars, wind dispersal of young larvae,
or by the removal of some object, such as an automobile or railroad
car, with attached egg case.
Control
Destroy eggs whenever possible.
In early
April, wrap 2" wide sticky
barrier bands around trees. There are many commercially
available products, which prevent caterpillars from climbing
up the tree.
The Gypsy moth has
many natural predators, such as mice, flies, beetles, and wasps.
Spray with
BT,
twice, 5-7 days apart.
Pictures
Gypsy
Moth (Life Cycle, page 53): A. large female moth;
B. small, dark male moth; C. pupa inside scanty thread cocoon;
D. pupa enlarged; E. full-grown hairy caterpillar (larva); F.
egg mass
Links
http://www.fs.fed.us/ne/morgantown/4557/gmoth/
http://www.beyondpesticides.org/main.html
(Click on Alternative Control)
ELM LEAF BEETLE
Location/Vulnerable
Plants
The Elm Leaf Beetle is believed to have reached Baltimore from
Europe about 1834. It is now enormously destructive throughout
New England and the Middle Atlantic States, occurs scatteringly
westward to the Mississippi, and is found on the Pacific Coast.
It is confined to the elm, with Chinese and Siberian elms most
severely injured.
Appearance
and Habits
The adult beetle is 1/4" long, yellow, changing to olive
with age, with black spots on the head and a black band on the
outside of each elytrum or wing cover. It winters in protected
places, often in houses, and in spring flies to the elm, where
it lays a double row of yellow, lemon-shaped eggs on the underside
of a leaf. These hatch in about a week into black-spotted larvae,
which skeletonize the leaves, eating out everything except veins
and epidermis. After 3 weeks of feeding, they crawl down the
trunk and pupate at the base, more beetles appearing in 1 to
2 weeks, to eat holes through the leaf. There are two or three
generations a year, with the elms either entirely defoliated
or covered with crisp brown leaves. Two or three years of defoliation
may mean death, and always mean a weakening of the tree so that
it is subject to attack by the elm bark beetle, carrier of the
spores causing Dutch elm disease.
Management
There are no proven methods of preventing the elm leaf beetle's
attack. Protect houses and garages, and keep the beetles from
wintering inside, by caulking cracks. Monitor the elms to see
if the damage is serious; if so, apply a narrow band of pesticide
higher than human reach. A relatively harmless homemade pesticide
of 3 ozs. laundry soap to 1 gal. of water will kill larvae coming
down to pupate.
Pictures
Elm
leaf Beetle (Life Cycle, page 53): A. adult beetle;
B. pupa; C. grub (larva); D. egg cluster on underside of leaf,
one egg enlarged; E. elm leaves showing skeletonization by larvae
and holes by adults.
ASPARAGUS
BEETLE
Location/Vulnerable
plants
The Asparagus Beetle arrived in this country from Europe about
1856 and is now widely distributed. Larvae and adults gnaw succulent
shoots and devour summer foliage, weakening the plants for another
year. Asparagus is, apparently, the only host.
Appearance
and Habits
The beetles are less than 1" long, bluish-black, with red
thorax, blue and yellow wing covers, the yellow often present
as spots. They winter in any protected place, often in trash
left around the garden, garages, and homes. As soon as asparagus
shoots appear in spring, they begin to feed and lay rows of
dark-brown eggs. Gray, black-headed slugs come out in 3 to 7
days, chew on the stems for 10 to 14 days, then pupate in the
ground for about a week. The beetles emerge and lay eggs either
on stems or foliage. There are at least two generations in the
North, more in the South.
The 12-spotted Asparagus
Beetle is orange to brick red with, yes, 12 black spots. This
species feeds on the shoots, but delays egglaying until shortly
before the berries form, when they glue dark green eggs to the
leaves. The orange larvae and second generation beetles feed
only on the berries.
Management
A clean garden is the best prevention. Eliminate any places
the beetle can hide, and till the soil to rouse them from hibernation.
Asparagus beetles
do not like tomato plants, and asparagus plants kill the nematodes
that often attack tomatoes. Intersperse the plants so that they
protect each other.
A cheesecloth netting
can protect tender young asparagus.
Birds, chickens,
and ducks love to eat the asparagus beetle, and ladybugs and
the chalchid wasp feed on the larvae.
Cut the asparagus
shoots every 2 or 3 days, before the eggs can hatch.
Dust asparagus with
bone meal or rock phosphate.
The spotted asparagus
beetle cannot fly in the morning, and can be handpicked.
Pictures
Asparagus
Beetles (Life Cycle, page 54): A. adult of common
asparagus beetle; B. adult of 12-spotted asparagus beetle; C.
typical injury by larva and beetles; D. grub (larva) and eggs
of common asparagus beetle.
COLORADO POTATO BEETLE
Location
The Colorado Potato Beetle is a native, and is so common that
it is referred to as simply the "Potato Bug." Found
in the Rocky Mountains feeding on Buffalo Bur about 1923, it
did not become abundant until the potato was introduced into
its territory. Then it spread eastward from potato patch to
potato patch, averaging 85 miles a year, until it reached the
Atlantic Coast and invaded Europe.
Vulnerable
Plants
Although potato is its preferred food, this beetle will eat
almost anything available, especially tomato, eggplant, tobacco,
pepper, ground cherry, thorn apple, jimson weed, henbane, and
thistle.
Appearance
and Habits
Adults spend the winter buried 8 to 10 inches deep in the soil,
emerging in time to feed on the first foliage of early potatoes.
They are wide, convex beetles, 1/2" long, with alternating
black and yellow stripes. Females lay up to 20 batches each
of orange-yellow eggs in groups on the underside of the leaves,
over 4 to 5 weeks. The eggs hatch into humpbacked, purplish-red
larvae, with 2 rows of black dots along each side. These larvae
eat voraciously, often entirely consuming the leaves. When full-grown
they descend into a spherical cell in the ground, transform
to a yellowish pupa, and in 5 to 10 days new adults emerge to
feed and lay eggs for the second generation.
Management
Grow potatoes above ground! Drop potato seeds on 3" of
sod or leaf cover and cover with straw.
Plant natural beetle
repellents nearby: flax, horseradish, garlic, eggplant, snap
beans, nightshade.
Handpick the beetles
and crush the eggs.
Dust the tops of
potato leaves with wheat bran. The beetles will eat it and bloat
up until they die.
Ladybugs and toads
eat beetles.
Spray with basil
water.
Spray foliage thoroughly
with lead or calcium arsenate, or cryolite, whenever beetles
or larvae are present. Either arsenical may be combined with
Bordeaux mixture for the control of blight, but cryolite may
be used only with a fixed copper free from lime.
Pictures
Potato
Beetle (life Cycle, page 54): A. pupa in soil and
adult beetle emerging from, soil; B. portion of potato vine
showing larvae, eggs and beetles; C. adult beetle, enlarged;
D. hump-backed grub (larva) enlarged; E. egg clusters on underside
potato leaf
Links
Ohio
State Extension, Colorado Potato Beetle in the Home Garden
JAPANESE BEETLE
Location
The Japanese beetle was first noticed in this country in 1916,
near Riverton, N. J. Presumably it came from its native Japan
as a grub in soil around the foots of nursery stock, or perhaps
in a shipment of iris or azaleas. Since its discovery this pest
has spread naturally from five to ten miles a year, to cover
from Maine to Georgia, and west to Michigan and Missouri.
Vulnerable
Plants
Adult beetles feed on foliage, flowers and fruits of almost
300 plants, and grubs work on grass roots. Some of the beetle's
favorite foods include: shade trees such as elm, horse chestnut,
linden, sassafras, white birch, willow; fruits - grapes, raspberries,
peach, apple, plum, cherry, quince; flowers - rose, hollyhock,
marigold, mallow, spiraea, zinnia; vines - especially Virginia
creeper; vegetables - corn, soybean, asparagus, rhubarb.
Appearance
and Habits
The beetles are about 1/2" long, shining bronze-green,
with bronze wing covers from under which protrude twelve tufts
of white hairs. They are particularly active on warm days, congregating
in crowds on the sunniest parts of plants. They are most active
on warm, sunny days, and fly only in the daytime. They emerge
in late spring and early summer, and are most active for four
to six weeks. Seasons following a particularly wet summer usually
bring a bigger population of beetles.
During this time,
each female lays from 40 to 60 eggs 2 to 6 inches deep in the
soil. The young grubs feed on grass roots until cold weather,
when they work their way down below the frost line. The grubs
are white, hairy, brown-headed 3/4 in. long.
Beetles leave only
the veins of leaves, and devour entire flower and fruits. Grubs
cut off grass roots so that the sod can be rolled back like
a carpet. Beetles feeding on corn silks prevent pollination,
resulting in sparse kernel development.
Management
The Japanese beetle has many natural enemies: the spring and
fall typhia wasps, birds, and skunks are helpful beetle enemies.
Avoid planting turf
or sod from outside the area, which may lack the nutrients to
support these natural enemies.
Milky spore disease
is harmless to plants, animals, and humans, but deadly for the
beetle. It is most effective in areas bigger than one acre.
Talk to a local garden group or county representative for more
information.
Remove diseased fruit
from the trees and ground, and keep the area weeded and clean.
Larkspur is poisonous
for the beetles, and they avoid the odor of geraniums.
Handpick the beetles
and drop them into a bucket of water with a think layer of kerosene.
Traps painted
yellow and baited with fermenting fruit, sugar, and water catch
thousands of beetles - empty this daily.
Pictures
Japanese
Beetle (life cycle, p. 51): (a) adult and damage
to peach, rose and corn, (b) egg in soil, (c) pupa in soil,
(d) grub and (e) damage to turf.
JUNE BEETLE
Location
June beetles, aka June bugs, daw bugs, May beetles, and white
grubs, include about 200 species and are distributed throughout
North America.
Vulnerable
Plants
More than 200 species injure grasses and vegetables in the grub
stage and trees as adults. Adult beetles eat leaves of oak,
ash, birch, pine and other trees, as well as blackberry leaves.
Grubs attack roots of corn, potatoes, soybeans and strawberries.
Appearance
and Habits
Most beetles have a three-year cycle. Large, dark-brown beetles
and white, brown-headed grubs winter in the soil. In spring
adults leave the soil at night, flying to feed on leaves, mating,
and returning at dawn to lay round white eggs in grassland soil.
The grubs hatch in two or three weeks and feed on roots until
fall when they work their way below the plow-line for winter.
Working upwards the next spring, they do most of their damage
this second season. They grow to about an inch long, being the
largest grubs commonly found in soil. The third season they
feed until late spring, pupate in soil, change to beetles in
late summer, but do not leave the ground until the next spring.
Heavy beetle flights are to be expected every third year, but
since there are different broods at varying stages in the life
cycle, some June beetles appear every spring.
Management
Rotate berries with deep-rooted clover and alfalfa.
Tear up infested
lawn and grasses, treat with organic fertilizer, and till and
plow deeply to destroy the grubs the summer before planting.
Handpick adult beetles.
Pictures
June
Beetle (life cycle, p. 51): (a) grubs, (b) egg in
soil, (c) pupa, (d) adult beetle.
SQUASH BUG
Location
The squash bug is common throughout the United States, ranging
from Central America to Canada.
Vulnerable
Plants
The squash bug attacks all vine crops, showing a preference
for squashes and pumpkins.
Appearance
and Habits
The adult bug is dark brown, sometimes mottled with gray or
light brown, hard-shelled, about 4" long. Because it gives
off a disagreeable odor when crushed it is commonly called a
"stink bug," but true stink bugs belong to a related
family. Unmated adults hibernate in the shelter of dead leaves,
vines, boards or buildings and fly to the garden when the vines
start to "run." Mating takes place at that time, and
clusters of brownish eggs are laid on the underside of the leaves
in the angles between veins. Egg-laying continues until midsummer.
The eggs hatch in a week or so into young nymphs with green
abdomens and crimson heads and legs, but older nymphs are a
somber grayish white with dark legs. There are five nymphal
instars, or periods between molts, in the two months before
the winged adult form appears.
Squash bug feeding
causes leaves to wilt, then turn black and crisp. Small plants
may be killed entirely, larger plants have one to several runners
affected. Sometimes bugs are so numerous that it is impossible
to produce any squashes; sometimes they congregate in dense
groups on unripe fruits.
Management
Keep squash bugs away from vine plants by also planting marigolds,
radishes, or nasturtiums.
Squash bugs like
to hide under boards or trash, wherever it is darka and damp.
Remove all potential protection.
Rotate crops.
Handpick
beetles and eggs.
Pictures
Squash
Bug
STRIPED CUCUMBER BEETLE
Location
The striped cucumber beetle is a native of the United States,
with a range from Mexico to Canada east of the Rocky Mountains.
Vulnerable
Plants
It is a serious pest of the cucurbit family, injuring cucumbers,
muskmelon, winter squash, pumpkins, gourds, summer squash and
watermelon about in that order.
Appearance
and Habits
The winter is passed as an adult - a small, 1/4 in. long yellow
beetle with three black stripes, hiding at the base of weeds
or under trash, often at some distance from the vegetable patch.
The beetles start feeding in early spring on blossoms and leaves
of various wild plants, but they migrate to the vine crops as
soon as these appear above ground.
Mating soon after
migration, the females lay yellow eggs, in crevices in the ground,
which hatch into small, worm-like, whitish larvae. These feed
on the roots for 2 to 6 weeks, pupate in the soil and, by midsummer,
produce beetles which feed on leaves and often fruits until
fall. There is one generation in the North, two or more in the
South.
Cucumber beetles
are injurious not only by the feeding of adults on leaves, stems
and fruits, and of larvae on the roots, but also because they
are carriers of cucumber wilt bacteria and the mosaic virus.
The bacteria, living over the winter in the beetle's intestinal
tract, are inoculated into plants as the beetles feed; the virus
is acquired while the insects are feeding on weeds in the spring
and then transmitted to the vine crops.
Management
Plant late, after the first beetles hatch. Start plants indoors
in containers.
Protect seedlings
with cheesecloth or nylon tents made by draping cloth over crossed
stakes.
Straw mulch keeps
adults from walking between plants.
Braconid
wasps, nematodes, and soldier beetles consume the cucumber beetle.
Pictures
Cucumber
beetle
SPOTTED CUCUMBER BEETLE
Location
It is found throughout the United States east of the Rocky Mountains,
increasing in importance towards the South.
Vulnerable
Plants
The spotted cucumber beetle, aka Southern Corn Root-worm or
Budworm, belongs to the same genus as the striped beetle but
is a much more general feeder. As an adult, it works on at least
200 vegetables, flowers, weeds and grasses, and as a larva,
feeds on roots of corn, beans, small grains, wild grasses. An
almost identical variety, often called the Diabrotica beetle,
is an important flower and vegetable pest in California.
Appearance
and Habits
The greenish-yellow beetles, 1/4 in. long with 12 conspicuous
black spots, hibernate in protected places under rubbish or
at the base of plants. In spring females lay their eggs just
below the ground surface on or near young corn plants; yellow-white
worm-like larvae with brown heads hatch to burrow into roots
and bud. The corn either makes poor growth or dies. As they
feed, the larvae also may disseminate bacteria causing corn
wilt.
Although spotted
cucumber beetles do not cause as much damage to cucurbit foliage
as the striped beetles they, too, are carriers of cucumber wilt
and mosaic. They are also particularly destructive to flowers,
being a common pest of dahlias, cosmos, chrysanthemums and other
late bloomers.
Management
Avoid injury to the corn crop by planting late on land plowed
the previous fall. For cucurbits follow directions given for
striped cucumber beetles.
Pictures
Cucumber
beetle
CODLING MOTH
Location
The codling moth, or apple worm, came to this country from Europe
about 1750 and quickly became our most destructive pest of apple
fruit.
Vulnerable
Plants
Codling moths also attack pears, apricots, cherries, peaches,
plums, quinces, crabapples and, in California, English walnuts.
Unfortunately, spraying with pesticides is often the only effective
method of controlling the codling moth, which is why these fruits
are the most highly-contaminated with pesticides. (http://www.foodnews.org/reportcard.php)
Appearance
and Habits
The insect passes the winter as a full-grown larva, an inch-long
pinkish-white caterpillar with a brown head, inside a silken
cocoon under loose scales on apple bark or in other sheltered
places. In spring the worms change to brown pupae and then grayish-brown
moths, 3/4 in. across the wings. These emerge to lay their eggs,
singly, on the upper surface of leaves, on twigs and on fruit
spurs. They work at dusk, when the weather is dry and the temperature
is above 55° F.
A cold, wet spring
at the time of egg-laying means less trouble with wormy apples.
Hatching in 6 to 20 days, small worms crawl to the young apples,
entering by way of the calyx cup at the blossom end. They tunnel
to the core, often eating the seeds, then burrow out through
the side of the apple, leaving a mass of brown excrement behind,
and crawl to the tree trunk to pupate. There are two generations
over most of the United States, and in some places a partial
third. Second-brood larvae enter the fruit at any point, without
preference for the blossom end.
Crop reduction comes
not only from wormy fruit but from early drop of immature apples
and from "stings" - small holes surrounded by dead
tissue which lower fruit value even though the worms are poisoned
before doing further damage.
Management
Plant cover crops that support moth-eating beetles.
Hand-remove and destroy
larvae.
Band trees with parasitic
nematodes.
Clean up the orchard
by scraping loose bark from trees and removing rubbish and all
dropped apples immediately.
Pictures
Codling
Moth (life cycle, p. 53): (a) adult, (b) larva, (c)
stage of fruit when first worms, enter, (d) eggs, (e) larva
working outward, moth, and "sting" lesions caused
by young larvae, (f) overwintering larva and pupa.
APPLE MAGGOT
Location
The apple maggot or railroad worm is a native, extending from
Canada to North Carolina and west to North Dakota and Arkansas.
Vulnerable
Plants
The maggot is particularly injurious to summer varieties in
northern sections of the country. It also attacks blueberries,
plums, and related flies infest peaches, cherries, and walnut
trees.
Appearance
and Habits
Hibernation takes place inside a small brown puparium buried
1 to 6 in. deep in the soil. The adult flies do not emerge until
summer (late June in some sections, early July in most). They
are a little smaller than house flies, black, with white bands
on the abdomen and conspicuous zigzag black bands on the wings.
The females lay their eggs singly through punctures in the apple
skin; in 5 to 10 days these hatch into legless whitish maggots
which tunnel through the fruit by rasping and tearing the pulp
into brown winding galleries. Early varieties soon become a
soft mass of rotten pulp; later varieties have corky streaks
through the flesh and a distorted pitted surface. Completing
their growth about a week after the apples have fallen to the
ground, the larvae leave the fruit and burrow in the ground
to pupate. Ordinarily pupation continues until the next summer,
but in its southem range, the apple maggot may have a partial
second generation.
Management
Immediately remove and destroy dropped fruit on a large scale;
this is effective only if implemented over several acres. If
the fruit is not too badly infested, it can be turned into cider.
Plant white clover,
home to beetles.
Hang fly-traps in
trees from mid-June through the harvest, baited with a mixture
of molasses, water, and yeast.
Maggots in picked
fruit may be killed by holding the apples in cold storage for
a month.
Pictures
Apple
Maggot (life cycle, p. 53): (a) adult fly, (b) pupa
and puparium in soil, (c) maggot, (d and e) damage to fruit.
SQUASH BORER
The squash
vine borer is a native of this hemisphere, occurring east of
the Rocky Mountains from Canada to Brazil.
Vulnerable
Plants
It attacks squashes and pumpkins and occasionally gourds, melons
and cucumbers.
Appearance
and Habits
The insect winters as a larva or pupa inside a silk-lined dark
cocoon an inch or two below soil level. The adult is a wasplike
moth, with copper-green forewings and orange and black abdomen,
appearing in June in the Middle Atlantic States. It lays 150-200
eggs, singly, on the stem, especially at the base of the main
stem, leaf stalks, blossoms. The young borers hatch in about
a week, tunneling into the stem to feed. Usually the first sign
of their presence is a sudden wilting of the vine, at which
time close examination discloses masses of greenish-yellow excrement
protruding from holes in the stem. The borer, a white, wrinkled
caterpillar about 1 in. long, can be seen by slitting the stem
with a knife.
Management
Baby blue and butternut squash can resist the borer to some
degree.
If a change in location
is possible, do not grow squashes two years in succession on
the same ground. If the same area must be used, spade or plow
it in the fall to expose the cocoons. Pull up and burn vines
immediately after harvest.
If a vine starts
to wilt, kill the borer with a knife and heap earth over the
stem joints to start new roots.
Make a second planting
of summer squash to mature after the first borer brood has disappeared.
Pictures
Squash
Borer (life cycle, p. 54): (a) adult female, (b)
cocoon, (c) egg and pupa, (d) larva in stem, (e) male moth,
(f) squash leaves wilting due to borer injury.
PEACH BORER
Location
The peach borer is a native of North America, found wherever
peaches are grown east of the Rocky Mountains. A closely related
species dwells in the West
Vulnerable
plants
It is most important insect enemy of peach trees, but also attacks
plum, wild and cultivated cherry, prune, nectarine, apricot
and various ornamental shrubs.
Appearance
and Habits
The first sign of injury is usually a mass of gum and brown
frass at the base of the tree trunk, indicating that white worms,
with brown heads, are working in the bark, anywhere from 2 to
3 in. below ground to 10 in. above. The winter is passed in
this larval stage; in spring the borers resume feeding, attain
their full inch-long size, then work to the surface of the bark
to form cocoons of gum, excrement and bark particles.
Shortly before moth
emergence, brown pupa cases are forced partly out of the cocoons.
The moths are a little over 1 in. across their wings; the males
are blue, with transparent, blue-bordered wings; the females
have an orange band around a blue abdomen, blue fore-wings,
transparent hindwings. Each female lays several hundred eggs
near the base of the tree trunk, young worms hatching in about
ten days to work their way inside the bark. Peaches seldom survive
repeated borer attacks.
Management
Dig
out the borers when you notice their gummy residue around the
base of the tree.
When planting peach
trees, make a tin "shield" that circle the tree and
fill the space between the shield and tree with tobacco dust.
This forms a protective pesticide layer.
You can also encircle
trees with moth balls or soft soap.
Coat bark of new
trees with Tanglefoot of Stickem.
Plant garlic
near the trees.
Pictures
Peach
Borer
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