Eastern Tent Catepillar
The eastern tent caterpillar can be a serious pest on cherry, plum, peach, pear, and several other deciduous shade trees. Common hosts are ornamental crabapples and cherries. These caterpillars do not feed on evergreens. The preferred host is native black cherry, which commonly grows on roadsides and hedgerows. Nests of the eastern tent caterpillars are unsightly and the repeated defoliation they sometimes cause can result in a decline of the host, predisposing it to damage from disease organisms and other insects. A single season's defoliation will seldom kill an otherwise healthy tree since feeding occurs early enough in the season for the trees to grow new leaves.
Description and Life Cycle
Adult moths are brown with a wingspan of about 1¾ inch. Two narrow, lightercolored bands may appear on the first pair of wings. The caterpillars are primarily brown and are thinly covered with light brown hairs. A white stripe on the back is bordered with reddish-brown stripes and a row of oval blue spots. Larvae vary in size from 3/8 inch upon hatching to 2 inches long when fully grown. They resemble the larvae of the forest tent caterpillars except they have a row of diamond-shaped white spots alternated with small white dots along its back and not the white stripe. Forest tent caterpillars, contrary to their name, do not build tents, feeding openly instead, often in large groups or clusters.
Eastern tent caterpillars overwinter in the egg stage. The eggs hatch in early spring soon after budbreak on the host plant. After hatching, the young caterpillars gather in a fork in the branches where they construct a web-like tent. Eastern tent caterpillars feed from four to six weeks and then disperse to various locations to spin cocoons and pupate. Cocoons may be found on fences, houses, in weeds and ground debris, and on the trunks of infested trees. Adult moths appear in late June to early July and are rarely recognized due to their innocuous appearance and short life span. After mating, the female will lay a batch of eggs, sometimes on the stems of very small trees. Only one generation occurs per year.
Damage
On warm, sunny days, the caterpillars will emerge from their tent – which is used mostly for thermal protection on cold spring nights – and feed on the expanding foliage. Often, there will only be one tent per plant and not all similar plants within close proximity will be affected. Damage can range from light to heavy defoliation depending on the size of the tree attacked and the number of webs per tree.
Management
• During the winter and prior to budbreak, prune out and destroy egg clusters on susceptible hosts.
• Newly forming webs in the spring can be pruned out or physically removed by hand, when the larvae are in the web.
• If nest removal is impractical, a spray containing Bacillus thuringiensis (B.t.), a bacterium, can be effective.
• Insecticidal soaps are effective on young caterpillars and should be applied only when the caterpillars are out of the tent and on the stems and foliage.
• Many chemical insecticides are also labeled for this pest.
Adapted from: David Gadoury, David B. Wallace, and Richard A. Casagrande, Revised 1999; UMass Extension
