This article aims to provide some general information about inchworms to our readers! Inchworms, which are technically caterpillars, are the larvae of geometer moths. They have several other nicknames including spanworms, cankerworms, measuring worms, and loopers. Their name is a reference for the way they “measure the earth” when they move. Inchworms have legs at the front and rear ends of their bodies, but no legs in the middle. To move forward, inchworms clasp with their front legs and move their hind legs forward, then clasp with their hind legs and reach for a new attachment with their front legs. This movement is captured perfectly in this video that a reader sent us:
There are roughly 35,000 different species of inchworms around the world, and about 1,400 in North America. They vary in color from green, gray, or brown, and hide from predators by resembling twigs and blending with their environments. Inchworms are often smooth, but some species have humps or filaments. Inchworms eat a variety of foliage, their specific food choice is often determined by their species. The feeding habits of a single inchworm is relatively harmless, but when a large population of inchworms feed on a single tree, they can cause serious damage to the foliage. Therefore, they are often considered pests by farmers and gardeners, especially inchworms that eat apple, mulberry, blueberry, pine, and fir trees and shrubs. While inchworm populations are often kept at bay by natural predators, they sometimes feed at night to avoid these predators.
Only one generation of inchworms is born every year. Adult moths lay their eggs on tree limbs in clusters of 50 or more. The eggs hatch in the late April or early May, and the caterpillars eat for 4-5 weeks. Next inchworms burrow underground and pupate in early June. However, they don’t emerge as adult moths until November, when they surface to lay eggs and start the cycle over again!
To wrap up, we wrote this article to provide some general information about inchworms to readers, and to share a wonderful video displaying inchworm movement.