This newly hatched monarch caterpillar is about 2 millimeters long (about 1/32 of an inch). After emerging from an eggshell, a typical monarch caterpillar eats all or part of its shell, which is a good protein source. The next foods are generally leaf hairs, followed by leaf tissue.

Two days after hatching in July 2003, this monarch caterpillar had chewed a small hole in the milkweed leaf. The caterpillar was 4 millimeters long (almost 3/16 of an inch), and was preparing to shed its outer cuticle and to undergo its first molt. CLICK TO LEARN MORE