Caterpillars are the larval stage of members of Lepidoptera (Insecta including butterflies and moths).

As with most common names, the use of the word is arbitrary, and the larva of serrata is often referred to as a caterpillar. Both Lepidoptera larvae and paragonial larvae have egg shape.

Most caterpillars are herbivorous, but not all. Some (about 1%) are insectivorous or even anthropophagous. Some feed on other animal products; for example, moths feed on wool, and hornmoths feed on hooves and the horns of dead ungulates.

Generally, caterpillars are voracious animals, many of which are the most serious agricultural pests. In fact, many moths are well known in their caterpillars stage, because they cause damage to fruits and other agricultural products, while moths are hidden and have no direct harm. On the contrary, all kinds of caterpillars are considered to be the source of silk, which can be used as food for human or animals, as well as biological control of pests.