The eastern tent caterpillar was seen in full force yesterday. Mostly a pest of Black cherry Prunus serrata here in the Southeast, it can sometimes be seen in several other common trees as well. The caterpillar forms a dense, white 'tent' in the crotches of tree branches, where the caterpillar rests.
While it is not a particularly damaging insect, it can weaken already stressed trees by causing the host tree to sprout new leaves. This resprouting leaves the tree with a short energy deficeit in the early spring.
It is rarely worth trying to control this insect unless they are active in a high-value tree. Broadcast sprays of insecticides work well but are environmentally risky; professional systemic control with Acephate is confined and effective.