Fall Cankerworm

A native species, cankerworms go through cycles of infestation and outbreak ranging from 2 to 7 years with periods of low population from 13 to 18. No major population outbreak has occurred since the 1970s, with isolated outbreaks occurring occasionally. The pest is often considered more of a nuisance
than a severe threat.

Latin Name

Alsophila pometaria

Trees Affected

Elm, apple, hackberry, basswood/linden, oak, boxelder, maple, and ash

Threat to Trees



Begins in early spring or fall and feeding occurs for about a month

Signs & Symptoms

Wingless females and egg masses on trunks in January and February, crown defoliation due to feeding and limb dieback after consistent defoliation of three or more years. Young, weak or newly translated trees are most susceptible.


Small larvae feed on small parts of leaves, older larvae consume entire leaves. Fall cankerworms are often considered more of a nuisance with caterpillars spinning to the ground on silk strings and climbing walls during spring and fall months.

Domestic Origins


Geographic Location

Throughout United States

Photo Credits