Caterpillar is eating leaf

Caterpillars are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths).
Caterpillars of most species eat plant material (often leaves), but not all; some (about 1%) eat insects, and some are even cannibalistic. Some feed on other animal products. For example, clothes moths feed on wool, and horn moths feed on the hooves and horns of dead ungulates.