Larvae are gray caterpillars 2" long, with long brown hair. They eat tree foliage of all kinds. Eggs hatch in late April or early May and larvae search for food immediately. At early stages, damage to leaves is slight and is often overlooked, but the early stages are when these pests are most vulnerable to control. In their last stage before becoming moths, the larvae feed en masse, causing overnight defoliation. In late June or early July the caterpillars stop feeding and begin transforming into adult moths.
Crucial control period is late April to June 15th. By mid June the caterpillars have grown to 3/4" long and have begun to defoliate leaves. By applying spinosad at 10- to 14-day intervals in April through June (three or four applications), damage to leaves can be almost totally eliminated. Just two applications are enough to prevent noticeable defoliation. Spraying with pyrethrins also controls larvae. We recommend Bull's-Eye Bioinsecticide and Pyola Insect Spray.