For several years, the end of May through the first of June has brought different varieties of unwanted worms and caterpillars to our landscapes. Recently, I have had a few reports of spring cankerworms being a problem. I usually don’t hear much about spring cankerworm problems, but periodically, we can have widespread outbreaks of them.
Spring cankerworms, which are actually caterpillars, will feed on several types of trees and shrubs and seem to especially like shade trees. Cankerworms are often noticed swinging down from tree limbs on thin silk strings to get to the ground. You might also find them crawling on your sidewalks, driveways and patios and crawling up walls.
Typically, spring cankerworms only produce one generation of young a year, which I guess is one good thing about them. Female cankerworms are wingless, so they walk up tree trunks and onto tree branches to lay their eggs in clusters in crevices on the trunks or on the limbs. Larvae soon hatch and start feeding on leaves for the next couple of weeks. When they are finished feeding, they drop to the ground on the silk threads and pupate in the soil until next fall.
While cankerworms are pupating in the soil it is a good time to apply beneficial nematodes to the soil to eliminate them before they emerge again in the fall. Spinosad or BT (Bacillus thuringiensis) can be used to get rid of these pests before they pupate.
With the recent rains, it’s also a very good time to put out nematodes to help get rid of fleas, ants, thrips, cucumber beetles, flea beetles or cutworms.
Until next time, let’s try to garden with nature, not against it, and maybe all our weeds will become wildflowers.