Eastern Tent Caterpillar

By:  Eddie Ayers, County Extension Agent

As I ride through the county I’ve noticed some webs are back in the wild cherry trees but before you start having nightmares about the webbing we had last fall, you can rest assured that this insect is different.  This culprit is the Eastern Tent Caterpillar. The webs serve as a home to the newly emerged larvae or as we like to call them, caterpillars. The eggs are timed to hatch when the cherry buds unfurl as they need to eat to grow and complete their life cycle.

Older larvae are generally black, with long brown hair and a white stripe down the middle of their backs. Along the midline is a row of blue spots with brown and yellow lines. At maturity, the caterpillars may reach a length of 2½ inches. The adults are reddish-brown moths which have two white oblique stripes on each forewing.  These are harder to notice, but they are the final step in the life cycle.

The adult moths emerge in May and early June and lay egg masses that resemble chocolate-colored collars that encircle the smaller limbs of their host. Each egg mass is about 1 inch long. Eggs overwinter and hatch in mid-March of the following year to start the cycle again. From each egg mass, several hundred tiny feeding machines emerge, and for four to six weeks they hungrily strip the trees of their leaves. The larvae are gregarious and upon hatching they gather in the forks of the limbs and develop the web that can be seen in the trees.  This serves as their home for the larvae. From this mass of silk, the developing larvae move outward to feed on developing leaves, but they return at night and during rainy weather. The nest gradually becomes larger and larger as silk accumulates. Although the nests are most commonly seen in the forks of wild cherries, this pest can be found in other ornamental, shade and fruit trees, especially apples. While not a serious pest in the natural forest, the unsightly web insect can reduce the beauty and esthetic value of shade trees and other hardwoods in the landscape.

About four to six weeks after hatching, full-grown larvae will crawl away from their nests and accumulate on the sides of homes, on driveways and sidewalks and on various woody ornamentals in search of sites to complete the next phase of life, the pupae phase.  This phase is a shell or cocoon in which the caterpillar matures into a moth. There is concern that they may be attacking other plants, but when they do leave their web, the larvae are finished with their feeding and will do no damage to plants on which they are found. The caterpillars are primarily a nuisance and do not usually pose a danger to the overall health of a larger, well-established tree as the tree can produce another flush of foliage.  However, young fruit and ornamental trees may be damaged, so it is a good idea to remove the web from these trees.

Usually, no chemical controls are necessary or very effective.  One reason is that the web is water proof and insecticides that are applied usually do not reach the larvae but you can break open the web and apply an insecticide such as carbaryl (Sevin), BT or a pyrethroid if you would like. If you decide to use an insecticide, please read the label and follow the instructions.  In addition, the egg masses can be clipped from the limbs in late June to prevent nests from developing the following spring.

For more information about the webs in trees right now, contact me in the Gilmer County UGA Extension office.