USDA Forest Service - Northeastern Area Archive, USDA Forest Service, Bugwood.org
Orangestriped Oakworm
Anisota senatoria (J.E.Smith) The orangestriped oakworm is sometimes very abundant on oaks in late August and September. Willow oak and pin oak tend to be their preferred hosts. They occasionally feed on other hardwoods as well. The moths emerge in June and July and deposit their eggs in clusters of several hundred on the underside of oak leaves. The eggs hatch in about a week or so. The tiny, green-colored caterpillars begin to feed together consuming leaves except for the midrib. Gradually small greenish caterpillars grow into larger black caterpillars with yellow or orange stripes running lengthwise along their bodies.
Young caterpillars feed in groups, whereas older caterpillars tend to spread out and feed on their own. There may be thousands of caterpillars on a single tree. Small trees are sometimes defoliated completely by mid summer. Even mature oaks may be defoliated to the point that there may be some twig dieback due to sun scald or other factors.
As the caterpillars mature, in late August or early September they drop to the ground and are often seen crawling across sidewalks and driveways, yards, etc. These caterpillars may wander for a considerable distance while searching for a place to pupate. They dig into the soil three or four inches and pupate there. There is usually one generation per year and the caterpillars overwinter as pupae in the soil.
