You may see yellownecked caterpillars feeding in trees this time of year. The following is more infomation.
Yellownecked caterpillars have a jet black head, yellow and black stripes and some white hairs. Directly behind the head is a bright yellow-orange segment. Oaks are often attacked along with basswood, maples, elms, walnut, fruit and nut trees. Adults emerge during June-July, mate, and females lay eggs on the undersides of leaves. This caterpillar feeds gregariously, skeletonizing leaves as early instars and consuming most of the leaf when they are older. When disturbed, larvae assume a “Ushaped” defensive posture to reduce the likelihood of attack by predators and parasitoids. Larvae actively feed between July through September depending on location and when eggs were laid, but there is only one generation per year. Birds, predatory insects, and parasitoids attack this pest. This pest seldom causes serious harm to trees and treatments are not often warranted. Chemicals available for control include B.t., spinosad, azadirachtin, or one of the pyrethroids.
Yellownecked caterpillars. Photo by Gerald J. Lenhard, Louisiana State Univ, Bugwood.org
Information from Brian Kunkel, Ornamental IPM Specialist, UD