Photo by Drees. Photo by Drees. Photo by Drees. Nymphal stages lack fully-developed wings and appear oval, marked with blackened areas and adorned with spines.
Adults become active in the spring when leaves appear on the host plant.
Development from egg to adult occurs in about 30 days depending on temperature and other environmental conditions. Three to five generations can be produced annually. Winter is spent as an adult in crevices of host plant bark. All life stages occur together on the undersurface of leaves on sycamore, ash and hickory. The underside of infested leaves become marked with black varnish-like excrement spots and cast skins of previous developmental stages often remain attached to infested leaves.