Thus transformed, they twitch from side to side in a startling manner. Similarly, hag moth caterpillars, sometimes called monkey slugs, look like hairy spiders, complete with pseudo-legs. Hag moth caterpillars may even scare their parents away, as spiders are important butterfly and moth predators. Web-building spiders, especially nocturnal ones, set their traps for moths when they are potentially a rich food source. But moths, and, to a lesser extent, butterflies as well, have a non-stick or slippery defense.
Wing scales are powdery structures that slip easily off the wings.
When a moth or butterfly strikes an orb spider web, the scales stick to the web's gluey droplets and the moth or butterfly does not. In turn, spiders have evolved various specializations to increase their moth-trapping ability. The ultimate spider weapon, found in bola spiders and others, may be synthesizing a copy of a female moth's sex attractant perfume. This lures male moths to their doom. Lepidopteran marvels abound.