In heavy infestations they can completely defoliate the entire tree. Apparently trees on high ground with poor soil are rarely, if ever, attacked. In some years, depending on the region, many trees will have all their leaves stripped away by the end of the summer. This may be followed by years with no defoliation observed at all. The fluctuation between outbreak and no defoliation is largely due to the activity of parasites.
Mature caterpillars have black heads and a broad black stripe running the length of their back.
The sides of the caterpillars are white or pale yellow and sometimes have black spots or vertical bands. There are pale forms that are more greenish and in some cases will have a row of black spots down the back or will lack the black stripe. The adult is a brownish-gray sphinx moth. Eggs are laid in clusters of up to 1000 eggs on the underside of the leaves. Life History Catalpa sphinx overwinter as pupae in the soil and the adults emerge in May and lay eggs on new leaves.