Author: Eric R. Day, Insect Identification Laboratory, Department
of Entomology, Virginia Tech
Insect:Host(s) Description Treatment timing*
FIELD AND VEGETABLE CROPS
Blister Beetles: Slender beetles 1-2" in Beetles usually appear
Potato, tomato, length which may be black suddenly and may cause
melon, eggplant, with white margins or black much damage before
sweet potato, and yellow striped. They they are detected.
bean, pea, and feed on the flowers and Spot treatments when
many other crops foliage. they are found will
Cabbage Looper: Green larva with three give good control.
Crucifers sets of prolegs and white Insecticide or "Bt"
stripes running the length applications made on
of its body. When it crawls 7-day intervals are
it moves like an inchworm. necessary to control
this insect.
Colorado Potato Adults are yellow with For small gardens,
Beetle: brown stripes, they are beetles can be removed
Potato, tomato, oval-convex in shape. The by hand-picking;
eggplant,pepper, larva is yellowish red or larger areas or heavy
tobacco, and orange and has a row of infestations will
other solan- black spots along each side require the use of
aceous plants of its body. insecticides.
Corn Earworm: Earworm larvae have a wide Based on a survey conducted
Soybeans range of colors, from July 19-28, corn
pale yellow to dark brown; earworms are expected
many are greenish. They to be at high levels
all have pale stripes and this year on soybeans.
orange-yellow heads. Scout all your soybean
fields, especially
ones with open
canopies, on a regular
basis and treat if
necessary. See Report
at the end of this
issue.
Cowpea Curculio: This weevil is 1/4" long, Late planted crops tend to
Beans and peas blackish-bronze in color, be less severely attacked.
and has a humpbacked Crop rotation and sanita-
appearance. Adult beetles tion also help in control.
puncture the pods and lay Commercial beans will need
eggs on the seed. This chemical control starting
insect tends to be a when blooms first appear.
problem in home gardens
and minor in commercial
plantings.
Cucumber Beetle: Two beetles feed on cucur- Foliar sprays
Cucumber, can- bits in Virginia: the spot- may be necessary in some
taloupes, gourd, ted cuc. beetle is pale cases. To prevent bac-
squash, and green with black spots on terial wilt treat when 1
watermelon are its wing covers; the beetle per 100 row feet
preferred hosts. striped cuc. beetle is pale is found.
They are found green with black stripes
on other crops on its wing covers. Both
but are not as transmit bacterial wilt of
important. cucurbits.
Fall Armyworm: Tan to dark larvae with For corn and sorghum treat when
Corn and other light colored longitudinal 80% of the plants have at
grasses as well stripes on its back, as least one caterpillar, or if
as many well as an inverted "Y" there are two or more cater-
vegetable crops on its head. Start scouting pillars treat corn when 40%
late July and August. infested and sorghum when 50%
infested.
Grasshoppers: The Differential Grass- Avoid mowing border areas
All crops hopper is dark green with with heavy grass and weed
yellow bands. The Red- growth; grasshoppers will
legged Grasshopper has red move from those areas to
legs. Grasshopper damage the crop plants after their
leaves are jagged and host plants have been cut
tattered. down. Treat with an
insecticide if damage
becomes severe.
Imported Velvet green larvae with a Treat when caterpillar
Cabbageworm: faint yellow stripe down populations reach a threshold
Cabbage, broc- the back and a row of of one worm per plant, repeat
coli, cauli- yellow spots on each side. every 5 to 7 days as needed.
flower, and
other crucifers
Mexican Bean Adults are hemispherical Insecticide applications
Beetle: in shape and yellowish- are recommended if more
Bean crops brown in color. They have than 30% defoliation takes
black spots on the wing place.
covers. The larvae are
less then 1/2" long and
have many spines.
Spider Mites: Damage is more noticeable Mites tend to be a dry
Over 180 host than the mites themselves; weather problem. Treat
plants including look for yellow stippled with a miticide if
many weeds, soy- leaves that often take on dry conditions are
beans and other a sand-blasted appearance. expected to continue.
beans tend to be Shake the leaves over a
hard hit piece of paper and look
for small pale mites
crawling around.
Stink Bug: Barrel shaped eggs are Removing weedy growth that
Many crops but laid on the undersides of harbors stink bugs will cut
in particular leaves; nymphs are black down on native breeding
pepper and and white or red or green. sites. Spot treatments of
tomato Adults are green or tan. insecticides when stink
All stages have piercing- bugs are seen is recom-
sucking mouth parts. mended.
Damage to pepper and
tomato appears as white
halos and deformations
on the fruits.
Squash Bug: Nymphs are grayish white Handpicking works well
All cucurbits; with dark heads and appen- in small gardens. Chem-
squash bugs pre- dages. Adults are oval ical control might be
fer squash, elongate, light gray, and needed in larger
pumpkin, cucum- mottled yellow on the operations.
ber, and melon underside. Nymphs tend
in that order to be found on the basal
portions of the vine.
Squash Vine Plants suddenly wilt and die; Borers can be cut
Borer: the plants on close exam- out with a sharp knife in
Primarily squash ination have white grub- small plantings; heavily
and pumpkin, but like caterpillars boring infested plants should be
other cucurbits into the basal portions of pulled out. Large plan-
are occasionally the vine. tings may need insecticide
fed upon applications made at the
base of the plants.
Thrips: Small slender yellow This insect tends to be a
Wide range of insects feeding on the problem during dry weather
field crops, flowers and foliage. Damaged and insecticides are
vegetable crops, foliage tends to be spotted only recommended if dry
and floral crops with white when heavily fed conditions are expected
upon and damaged flowers to continue with no rain
are brown and tend not to showers.
to open.
Western Corn Pale cream colored larvae See PMG 016, Section 4 on Insect
Rootworm: tunnel and feed on the Pests of Corn for the latest
Corn (only) roots. The more conspicuous control methods for Western Corn
adults feed on the silks Rootworm. Also has scouting and
during July and August. thresholds.
The adults are pale green
with three black stripes
on their wing covers,
sometimes the black stripes
are fused together to make
the wing covers appear
solid black.
Whitefly: Small dusty white flies Insecticidal control is
Many vegetable found in the underside of recommended for large pop-
crops, but the leaves. Pale nymphs ulations. This is a very
tomatoes tend to are also found on the under- difficult insect to
be hard hit. sides of the leaves. control.
Their feeding causes the
leaves to become mottled
with yellow.
FRUIT INSECTS
Codling Moth: Pinkish-white caterpillars If using pheromone traps,
Apple and pear enter fruit at calyx end treat if you exceed 5/trap/
primarily, but and tunnel all the way week.
cherries,peaches, to the core. Adult moths
plums, apricots, are grayish-brown with
and similar irregular golden brown lines
fruits are also on the fore wings. 1/2-3/4"
attacked. wingspan.
European Red Mites are very small and This mite is resistant to
Mite: Apple range from red to green. many miticides, so make sure
pear, plum, Foliage turns a sickly that the chemical you will use
prune, and bronze color as if covered is effective. A dormant oil
many other with dust. applied at the 1/2" green leaf
trees and shrubs stage or earlier in the spring
is important also.
Lesser Peach- Look for brown pupal cases Treat immediately post-
Tree Borer: protruding from wounds on harvest.
Peach, plum, scaffold limbs.
cherry, nectarine,
apricot
Peach Tree Look for a mass of gum Adults emerge July-
Borer: Peach, and frass at the base of September, treat immediately
plum, cherry, the trunk; white larvae post-harvest.
nectarine, will be found under the
apricot bark from 3" below the
soil level to 10" above.
San Jose Scale: Scales are dirty gray Treat early August in
Apple, pear, with a dark concentric severe cases, otherwise
cherry, and many ring on the center. wait until spring. See
other fruit trees Scales infest the bran- PMG for timing.
ches, twigs, and fruit.
Spotted Tentiform Young mines are serpentine Treat young mines with
Leafminer: changing to oval. As the Vydate or Lannate if more
Apple larvae get older they than 3 mines per leaf.
form the leaf into a tent-
like structure.
Variegated Leaf- Eggs are laid in masses in Treat when egg masses are
roller and which the eggs overlap about to hatch (dark head
Tufted Apple much like fish scales. stage).
Budworm: The egg masses are found
Both are general on the leaves.
feeders but are
pests on apple
and peach
White Apple Look for small, pale, Check several trees and
Leafhopper: leafhoppers on the under- treat if a high density is
Apple sides of the leaves. This found on all trees. This
will be the second pest may be bad in regions
generation. with dry weather.
ORNAMENTAL INSECTS
Bagworm: Caterpillars form "bags" Pick off and destroy all
Conifers, maples around their bodies made of bagworms now and/or treat with
sycamores, box- silk and plant debris. an insecticide in mid-
elder, and many They overwinter as eggs June. Early next spring pick
others in the bags; the eggs off all bags you can find.
hatch in late May and
early June.
Euonymus Scale: Females are dark brown Treat May 10 and 20,
Euonymus, oyster-shaped, males are and Aug. 5-15.
bittersweet, and elongate and white.
some ivy ground Crawler stage is May 5-
covers. June 10; and Aug. 1-25
Fall Webworm: Eggs are laid in a mass Nests can be pruned out in
Most fruit and of 200 to 500 often cover- early summer or if a large
nut trees as ed with a woolly layer of numbers of nests exist, treat
well as some scales. Large groups of mid- to late-June or when new
hardwoods and larvae form a nest at the larvae appear. Nests are
shrubs tip of a branch. still apparent this time of
year but control is not
warranted for full grown
larvae because they have
finished feeding.
Japanese Scale: Long and narrow scale, Treat at 2-week intervals
Maple, privet dull white in color, from June 1-Sept. 1.
often found on the
trunks and branches.
Juniper Webworm: Webs will usually be Prune off and destroy any
Juniper and formed on on the upper active webs. Insecticide
red cedar branches and will include controls, if needed, should be
frass and dead needles. applied late July-early August.
Mimosa Webworm: Larvae feed gregariously Treat when trees show
Mimosa and in a web spun over the first signs of feeding in
honeylocust flowers and leaves and June. May need to repeat in
later feed individually mid-July and mid-August.
on leaves and pods.
Obscure Scale: Scales are circular, Treat white oak in mid August.
Oak, pecan, elm grayish, and closely Treat red oaks and other trees
hickory, hack- resemble tree bark. They in mid July.
berry can usually be found on
twigs and branches. Small
branches may be killed.
Pine Bark Aphid: Look for cottony masses Treat late-June and
Principally on on the bark and branches mid-August. Make sure the
white pine but covering small, aphid-like, insecticide is applied with
on other pines pale-green insects. strong stream that penetrates
as well the "cotton". Small populations
can be dislodged with a strong
stream of water alone.
San Jose Scale: Scales are dirty gray Treat late July-early August.
Many trees and with a dark concentric
and shrubs ring on the center.
Scales infest the bran-
ches, twigs, and fruit.
Spruce Mite: Small mites, 1/50" long, Spray with a miticide
Arborvitae, cause a yellow stippling early fall.
spruce, juniper, on the needles and die-
hemlock back of lower branches.
Yellow Poplar Small black weevils make Many yellow poplars will have
Weevil/ Sas- rice shaped holes on leaves turn yellow and brown
safras Weevil: the underside of the leaves. prematurely; this is
Yellow poplar, Larvae make blotch type from damage that occurred
sassafras, mines on the same leaves earlier this year.
magnolia the adults fed upon. It is too late for control
This pest has not been this year.
as bad this year as it
was in 1987 but some trees
have had leaves turn brown.
White Peach The female scale is white Treat July 5-15, and
Scale: Most with a yellow mark on the September 1-10. Next year
fruit trees and center and has a rounded treat also May 1 and May 10.
many ornamentals shape. The male is solid
white and elongated in
shape. Crawler stage is April
25-May 15, and July 1-15, and
August 20-September 15.
* See Virginia Pest Management Guides for recommendations on insecticides and rates. Use insecticide applications only when high population levels demand control action. Most plants can support small populations of pest insects.