Caterpillars are the larval form ofmoths,butterflies, andskippers. Like allinsects, they have three pairs of true, jointed legs, which are attached to the three thoracic segments of their cylindrical bodies. Most species also have several pairs of fleshyprolegs on their abdominal segments. Prolegs are usually tipped with curved rows of minute hooklets to help the animals hold on to surfaces, such as twigs and leaves. The caterpillars of many familiarlepidopterans, such asmonarchs (Danaus plexippus) andhawk moths (family Sphingidae), have prolegs on segments 3 through 6 and 10 of the abdomen (that is, four pairs on the mid-abdomen and one pair near the anus), though the number may be reduced in some species. For example,inchworms (family Geometridae) andcabbage loopers (Trichoplusia ni, familyNoctuidae) have only two or three pairs of prolegs, which is why these caterpillars draw their hind end up to meet the front before extending forward again. The unusualslug caterpillars (family Limacodidae) have suckers instead of prolegs and seem to glide rather than crawl.