Males are black, but females have a red abdomen.
The young larvae feed on immature leaflets which then fail to develop properly. Instead the leaves develop into oblong pod-like hollow, galled leaflets, each of which contains one or more larvae. In severe infestations, the leaflets of the honeylocust tree dry up and drop prematurely. Repeated attacks cause the death of small branches. In northern New York there is normally one generation of this insect each year.