Found perched about as shown here, angled head-lowermost from dead twigs of hackberry. On capture it released a large green drop of fluid from its rear end (only did this once). On further disturbance thrashed vigorously. By about June 4 it was forming a tough cocoon of reddish silk among leaves. Adult eclosed June 19.
While Geometroid Caterpillars states that caterpillars overwinter, Caterpillars of Eastern North America says the pupa does.