Author: Eric R. Day, Insect Identification Laboratory, Department
of Entomology, Virginia Tech
Insects to be on the Lookout for in May
Insect:Host(s) Description Treatment timing*
FIELD AND VEGETABLE CROPS
Aphids: Look for small soft- Cut out and destroy small
Any crop but in bodied insects causing localized areas on plants or
particular cru- the leaves to be stunted, treat with an insecticide
cifer crops yellowed, and/or curled. labeled for aphids and that
particular crop.
Black Cutworm Medium to large cater- If more than 5% of the plants
and other pillars cut off plants are cut, control with an
Cutworms: at the base. Inspect insecticide or bait is
Many crops but newly planted seed beds warranted.
in particular and newly set plants.
corn
Flea beetle: Small black beetles jump- Spray with Sevin when damage
Corn, eggplant, ing like fleas when dis- becomes severe.
and many other turbed form the leaves of
crops a plant. They scrape the
upper epidermis layer off
the leaf and sometimes the
fruit, leaving a brown scar.
Imported Velvet green caterpillars Treat when caterpillar
Cabbageworm: with a faint yellow stripe populations reach a threshold
Cabbage, broc- down 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 Full grown larvae are about
other crucifers 32 mm (1-1/4 inches) long.
Root Maggots: White legless maggots Usually a planting time soil
Many vegetable feed on small roots and insecticide is needed but a
and field crops, tunnel into large roots. soil drench after plants have
particularly Plants with damage fail been set may be effective.
crucifer crops to develop properly. Replanting is effective
because there is usually only
one generation of maggots and
the second planting is not
attacked.
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.
cherry, peach, to the core. Adult moths
plums, apricots, are grayish-brown with
and similar fruits irregular golden brown lines
are attacked on the forewings. 1/2-3/4"
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
prune, and bronze color as if covered use is effective. A dormant
many other dust. oil applied at the 1/2" green
trees and leaf stage or earlier in the
shrubs. spring is important also.
Green Apple Pale green nymphs on the Treat when 50% or more of the
Aphid: underside of leaves and shoots are infested.
Apple, pear new shoots, often a pro-
blem on trees with exces
sive shoot growth due to
overfertilization.
Spotted Tenti- Young mines are serpentine Treat young mines with Vydate
form Leafminer: changing to oval. As the or Lannate if more than 3
Apple larvae get older they form mines per leaf on average.
the leaf into a tentlike
structure.
ORNAMENTAL INSECTS
Azalea Stem Look for tips dying back Treat mid-May and mid-June
Borer: Azalea, and yellow legless grubs with an insecticide or cut
rhododendron, up to 1/2" long boring in out and destroy dead and mountain-laurel,
blueberry dying tips as noticed. twigs and trunk. Use of a borer
paste in the holes
will give some control also.
Boxwood Adults are out April to Apply insecticides for
leafminer: early May. Infested leaves adults; apply systemic
Boxwood often appear blistered and insecticides in early to
discolored. See the March late June to control larvae.
1990 issue of the Plant
Protection Newsletter for
more information.
Bronze Birch Look for the top of the Treat mid-May, and early-,
Borer: Birch, tree dying back and up mid-, and late-June; spray
cottonwood, to 1" long flat-headed trunk and branches heavily
poplar, aspen borers under the bark. and leaves lightly.
Camellia Scale: Scale is light to dark Treat May 10 and 20 and/or
Camellia brown, 1/10" long and Sept. 10 and 20.
oyster-shaped. Crawler
dates are May 1-June 5;
and Sept 15-30.
Dogwood Borer: As many as 50 white cat- Treat mid-May, repeat at
Dogwood, some erpillars with brown 6 week intervals 2-3 times.
times pecan heads living under rough-
ened areas of the bark.
Dogwood Twig A slender lemon-yellow In early to mid-May, apply
Borer: Dogwood beetle grub feeding in an insecticide spray to
elm, viburnum, the center of twigs. As control the adults. Prune out
and many fruit it feeds it makes small and destroy infested twigs.
trees holes to the outside for
the protrusion of frass.
Eastern Tent Look for conspicuous egg Pick off egg masses before
Caterpillar: masses circling twigs. they hatch. Treat with an
Many fruit trees These egg masses will be insecticide as soon as the
but in particular black in color and quite leaves have emerged enough
cherry shiney as if varnished. to retain the insecticide.
The small black hairy
caterpillars will hatch
out in April and feed on
the newly emerging leaves.
Elm Leaf Newly hatched larvae are Control newly hatched larvae
Beetles: Elm yellowish with black mark- in late-May and early-June.
ings, adults are olive
green with two black lines.
Euomymus Scale: Females are dark brown, Treat May 20-25 and
Euonymus, oyster-shaped, males are and Aug 5-15.
bittersweet, and elongate and white.
some ivy ground Crawler dates are May 5-
covers. June 10 and Aug 1-25.
Florina Hemlock Cast skins give trees a Treat May 20-25 and
Scale: Hemlock white-washed appearance June 5-10.
fir, spruce, yew. with many scales on the
undersides of needles.
Scales under close examination
are yellow in color.
Crawler stage peaks
May 15-June 20.
Hickory Leaf Galls shaped like No control is needed on established
Stem Gall: bullets develop on the trees as these galls do not harm
Hickory. petioles and shoots. large trees seriously.
Leaves with galls fall Young nursery stock can in
off the tree prematurely, some cases be killed and an
causing concern by the insecticide applied just as the
tree's owner. Galls are leaves open may be warrented.
formed by aphids.
Lace Bugs: New damage will not be Lace bugs overwinter as
Andromeda, oak, apparent yet this year, adults on deciduous plants.
azalea, walnut, but last season's damage Treat in late May and repeat
rhododendron, appears as stippling in June and July. On evergreens
sycamore. and brown droppings on lace bugs overwinter in
the leaves. the egg stage.
Lilac Borer: Look for the white borer Control adults with an
Lilac, Ash, 3/4-1" long just beneath insecticide in early
privet. the bark. May and repeat six weeks
later. Borers can be killed in
their burrows with borer paste
or a long flexible wire.
Oystershell Scales are dark brown Treat May 5-10 and/or
scale: Most and oyster shaped. They July 15-20.
fruit trees and can build up to extreme
ornamentals. numbers at times and almost
cover twigs and small
branches. Crawler dates:
May 1-20 and July 15-25.
Pine Needle The female scale is white Treat May 5-20 and/or July 15-20.
Scale: Nearly and about 1/10" long. Its Single infested branches can be
all species of shape varies but is usually pruned out.
pine as well as wider at one end. The male
many other ever- is smaller and has 4 parallel
greens. ridges down the center.
Southern red mite: Damage is seen as finely Treat in late April to early May
Holly, pyracantha, stippled leaves with a and late September to mid-October.
azalea, camellia, yellowed, chlorotic, or
rhododendron, and russetted appearance.
other broad-leafed
evergreens.
Spruce mite: Small mites, 1/50" long, Spray with a miticide in mid
Arborvitae, spruce, cause a yellow stoppling May and early fall.
juniper, hemlock. on the leaves and die-
back of the lower branches.
in severe cases older branches
may turn brown and die.
White Peach Scale: The Female scale is white Treat May 1 and 10, Jul
Most fruit trees and with a yellow mark on the 5-15, September 1-10.
many ornamentals center and has a rounded
shape. The male is solid
white and elongated in shape
Crawler dates are April 25-
May 15, July 1-15, and
August 20-September 15.
White Pine Weevil: The larva is a yellow, Prune and destroy infested
Pines and spruces. legless grub that feeds shoots in May and June.
under the bark on the
terminal leader. The leader
wilts and droops in the
spring indicating the
presence of the grub.
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* See Virginia Pest Management Guides for recommendations on insecticides and rates. Use insecticides only when high population levels demand control action. Most plants can support small populations of pest insects.