Eastern Tent Caterpillars
Black cherry, chokecherry and apple are favored; also feeds on hawthorn, pear, plum, and flowering
Description of Damage
Eastern tent caterpillars initiate small silken nests (tents) for protection in branch crotches as soon as they hatch. Most larvae leave the tent during the day to feed on foliage, but return at night. Larvae defoliate increasingly larger portions of the canopy as they grow in size. They continually increase the size of the unsightly tent until it measures a foot (30 cm) or more in length. Leaves may be stripped completely when several tents occur in the same tree. Infested trees are often able to re-leaf in the spring after the initial defoliation and the caterpillars have finished feeding.
During the fall and winter months, cut off and destroy any egg masses found on twigs. Chemical control against the larvae should be done early in the spring while the larvae are small and actively feeding. However, larvae begin feeding on leaves opening from the bud in early spring, before there is much leaf surface area present to be treated with an insecticide. Spray treatments are not always successful if applied too early before the canopy has flushed out.
Most insecticides kill larvae by direct contact; however, any larvae remaining in the tent are protected by their shelter. Treat foliage and twigs during the day, when caterpillars are actively foraging outside the tent, using insecticides with residual properties. Residual insecticides will still be effective over a short period of time after spraying, killing any larvae that may have been protected in the nest but then emerged to feed on treated foliage. If treating fruit-bearing trees, use an insecticide labeled for use on fruit trees. Burning out tents with fire is not recommended as the tree will likely suffer damage
Homeowners are often concerned at the sight of migrating eastern tent caterpillars seeking protected places to pupate. The larvae are seen crawling on other types of plants, roadways, walks, buildings, etc., suggesting that infestations have spread elsewhere than from the original host tree. Mature, migrating larvae are no longer feeding, so insecticides are generally ineffective against this stage. Crushing any migrating larvae when seen will reduce the adult population to some extent. The nests of eastern tent caterpillar and those of the fall webworm may be mistaken for each other. However, eastern tent caterpillar spins nests in the crotches of trees, while fall webworm makes nest at the tips of leafy branches.
Fall Web Worms
Newly emerged larvae immediately begin to spin a silken web over foliage on the terminal portions of the branches. The larvae feed on the leaves within the webbing. As the larvae grow, webs enlarge and enclose more foliage. Large portions of tree branches are commonly enclosed by such webs and are most apparent from mid- to late-summer. Young larvae feed on the upper surfaces of the leaves while older larvae eat entire leaves except for the midrib and large veins. The insect is considered an ornamental pest due to the unsightliness of the webs, but it is usually not an important forest pest.
Nests can be cut out of small trees and destroyed. Insecticides may be applied against fall webworm from mid- to late- summer or when webs are first found.