This caterpillar has 8 pairs of legs. The three pairs in the front have claws for grabbing leaves to eat. These legs will become the legs of the butterfly. The back five pairs are called prolegs. They are short and have hooks on them for crawling up plants.Monarch caterpillars have a pair of short antennae near their mouths. Each antenna has a tiny knob at the end. Some scientists think that a butterfly hears and smells with its antennae. They have two pairs of black horns, possibly to use like whips or clubs against predators, one pair in the front, and the other pair in the back.

Caterpillars are the larval stage of butterflies and moths. The caterpillar hatches from a tiny egg, then spends its time eating and growing. This larval stage usually lasts from two weeks to about a month. As caterpillars grow, their exoskeleton becomes tight on them, so they molt (lose their old exoskeleton) Then the caterpillar pupates, covering itself with a protective shell, and metamorphosing into an adult butterfly or moth.

Anatomy: The body of the caterpillar (like all insects) is divided into 3 parts, the head, thorax, and abdomen. They have an exoskeleton, a hard, outer covering.

The ocelli (simple eyes that detect light) are located on the head. The mouth and jaws (mandibles) are also located on the head. Setae are sensory hairs located all over a caterpillar's body, giving it a sense of touch. The caterpillar breathes through holes in its side called spiracles. The six prolegs (attached to the thorax) will become the legs of the adult. The many prolegs will disappear in the adult stage.