Q: I’ve been battling inch worms in my Japanese maple for five years. They decimate the leaves and get all over everyone when they come up the walkway. Is there anything that can be sprayed to control them?
A: Inchworms, also known as cankerworms, love to eat maple foliage. Pupae overwinter in the litter beneath a tree. The wingless females crawl up the trunk and deposit eggs on small stems and leaves. The eggs hatch into caterpillars and immediately start chewing the greenery. If the worms are already present, spray the tree with Bacillus thuringiensis (click for sources).
The worms will immediately stop feeding. If they haven’t yet emerged, wrap the trunk with a band of duct tape four inches wide and cover it with a sticky product like Tanglefoot (click for sources). Check it for adult moths every week. The band can be removed in June.