Sawflies seem to be in abundance this summer on a lot of plants including hibiscus, roses, and jewelweed, among others. The larvae of sawflies are often confused with caterpillars. Sawflies are the larvae of young of wasps (Hymenoptera), whereas caterpillars become moths or butterflies (Lepidoptera). A key difference is that sawflies have more than five pairs of prolegs. Caterpillars never have more than five. Sawflies feed together and often curl up when disturbed.
One of the coolest looking sawflies is the butternut woollyworm (Eriocampa juglandis). The bodies of the larvae are covered with fluffy white wax. They feed on the leaves of black walnut, butternut, and hickory. Underneath the wax is a green body with a white head. There is one generation each year. If you see chewing damage on black walnut trees, turn the leaves over to look for the woollyworms. Just leave them be and enjoy them.
By Mary Kay Malinoski, Extension Specialist, University of Maryland Extension, Home & Garden Information Center