The very best way to control cankerworms, though, is to prevent them. Follow the procedures given below to keep these insects off your plants.
Later Winter Horticultural Oil Spray
Light Horticultural Oil - Before the leaves begin to show in spring, spray trees with a dormant oil to suffocate any over-wintering eggs.
Winter Barrier For The Females
Sticky Band Barriers -Create a sticky band and place it around the trunk of vulnerable trees to catch the wingless females that must crawl up to lay their eggs. Wrap a band of cotton batting or heavy paper around each tree trunk and coat it with Tanglefoot or some other sticky material. Place them on trees from mid-October to December and again in February.
Encourage Predators of Cankerworms
Animal Predators - Bluebirds, chickadees, nuthatches, tufted titmice, and other birds are terrific controls for cankerworm because they eat the eggs in the bark.
Insect Predators - Among the naturally occurring beneficial insects that kill cankerworms are the predatory beetles (such as ground beetles and soldier beetles), stinkbugs, tachinid flies, and a predatory mite, Nothrus ovivorus.