CANKERWORM. A caterpillar that is very structive to fruit and shade trees, often called the " measuring worm" or "inch worm." The canker worm moth lays her eggs on the bark of trees. She has to crawl up the trunk to do this, for only the males possess wings. When the eggs hatch the little hungry larvae or cankerworms soon devour all the foliage in their vicinity, often causing the trees to die.
When it is time for them to change into moths, they let themselves down to the ground by spinning a long thread of silk, and burrow into the earth for two or three inches, later coming forth as adult moths.
Birds are valuable natural checks for these pests, especially the little black-capped chickadees, the red and white-breasted nuthatches, the brown creeper, the ruby and golden-crowned kinglets, and the downy and hairy woodpeckers. It was with a view to getting rid of the cankerworms that the English sparrows were first imported from England to the United States, in 1851. (See Butterflies and Moths.)