In a natural setting, surviving trees can prosper in the absence of competition. Healthy ornamental trees and shrubs should survive even serious defoliation. Natural Enemies Tent caterpillars have numerous enemies. One is a tachinid fly which parasitizes the larvae by depositing white eggs on the caterpillar's body. When the egg hatches, a small maggot burrows into the caterpillar and begins feeding.
Tent caterpillars are also subject to a virus disease called wilt.
While such natural enemies will reduce the number of tent caterpillars eventually, this process is gradual and may take 2 or more years. During that time, the affected trees may suffer such severe damage, that they will not recover. An effective way to control tent caterpillars is to remove their egg cases from trees. The egg masses are a brown or gray frothy material which has hardened to look rather like Styrofoam. While some are long bands found on twigs, others are flattened shapes found on tree trunks or buildings.