The fall cankerworm, Alsophila pometaria, is a native insect named for the adult moths that hatch in late fall. It is often part of a complex of looper caterpillars, or inchworms. It can be found defoliating forests in the spring of almost any given year in Maryland. Sudden occurrence and disappearance of outbreaks are typical of this looper complex. Naturally occurring predators, parasites and diseases quickly lower populations. Therefore, it is difficult to anticipate defoliation from year to year.
In 1994, 319 acres were defoliated across the entire State. In 1993, the fall cankerworm and the half-winged geometer, Phigalia titea, formed a looper complex that defoliated almost 5,000 acres in western Maryland. In 1992, over 5,000 acres of hardwoods were defoliated in Allegany County. Extensive tree mortality occurred in Allegany County because trees defoliated by the looper complex were under extreme stress from previous gypsy moth defoliations and drought.