The gypsy moth is just one of many insects that feed on tree leaves. There are several caterpillars common to Fairfax County which are often mistaken for gypsy moth. Each of these has definite identifying characteristics which are true to the species. No two insect species have the same characteristics. The information provided here will aid you in differentiating the gypsy moth caterpillar from others.
EASTERN TENT CATERPILLAR
Caterpillars rest inside
the tents during the heat of the day or rainy weather and depart to
feed on leaves during the night. While tent caterpillars can nearly
defoliate a tree when numerous, the tree will usually recover and put out
Eastern tent caterpillar is not considered as serious a pest as gypsy moth because it feeds early enough in the season that the trees have enough energy stored to put out new leaves since they have not completely depleted those resources yet. Gypsy moth feeds in late spring and summer, and by then the trees have used up most of their resources to put out all the leaves; thus, it is much more difficult for them to put out new leaves again. Eastern tent caterpillar is also native to Fairfax County and has many natural enemies. Once the caterpillars are full grown, they stop feeding and begin to wander around on the ground and buildings looking for a protected place to pupate. Keep in mind that by this time, they will no longer be feeding or causing further damage to trees. Prevention and early control is important. Removal of egg masses during winter greatly reduces the problem next spring. Their egg masses are covered with a shiny, black varnish-like material and encircle branches that are about pencil-size or smaller. In early spring, small tents can be removed and destroyed by hand. Larger tents can be pruned out and destroyed or removed by using a long stick or broom handle.
Caterpillars are quite variable in color; either light green with yellow stripes to green with dark stripes or black with white stripes. They are smooth and hairless. Mature larvae will reach a length of about 1 inch.
These "loopers" or "inchworms" hatch in late March or early April.
Caterpillars hang by silken threads throughout the caterpillar stage, whereas the gypsy moth does so only in the early caterpillar stage. Learn more.
TUSSOCK MOTH CATERPILLAR
Caterpillars are yellow or white with black heads and black markings, and prominent tufts of hair. Mature larvae are 1-1 1/2 inches in length.
These caterpillars feed on walnut, linden, apple, hickory and oak. They are commonly seen in late May, June and July. They do not hang on silken threads or make tents.
ORANGE STRIPED OAKWORM CATERPILLAR
Caterpillars are black, hairless, with eight narrow orange or yellow stripes, and are about 2 inches long. There is a pair of long curved "horns" towards the head. They feed in groups, primarily on oaks for five to six weeks from July to September and do not hang by silken threads.
FOREST TENT CATERPILLAR
Caterpillars have pale bluish lines along the sides of a blackish body with a row of cream colored keyhole-shaped spots down the middle of their backs. They are sparsely covered with white hair and reach two inches in length when mature. They feed on the tops of oaks and other forest trees in late March to early April. They do not make a tent or webbing in trees or hang by silken threads.
Caterpillars are pale yellowish, greenish or brown with two rows of black spots down their backs. They are 1 1/2-2 inches in length when mature and covered with silky hairs. They are mainly hairless when young. Many pale yellow or light brown hairs appear as they grow older. Caterpillars emerge in late May and feed through August and will feed on a wide variety of tree species. They build large webs at the tips of branches and feed inside the webs.
These late season feeding pests rarely cause significant damage because the tree has already had enough time to store enough food and energy for the winter.
There are several other species of insects that can also cause damage to trees. The correct identification of the problem insect is essential to controlling the insect properly. Fortunately, the control of many of these pests is rarely necessary since they seldom cause severe damage.
For more information, please contact the Fairfax County Forest Pest Branch at 703-324-5304, TTY 711, or via e-mail. You may also visit the Virginia Cooperative Extension for more information about pesticide safety and insect identification and control measures.