The Cartoon Crawl! How Inchworms Move This little “cartoon caterpillar” is most likely an inchworm, the larva of a geometer moth (family Geometridae). Inchworms move with a looping, “hump-and-stretch” motion because they lack middle prolegs, the extra limb-like stubs most caterpillars use for walking. To move, they grip with their front legs, pull the rear end forward to form an arch, then anchor the back and stretch out again, repeating in a rhythmic wave. The name “geometer” means “earth-measu