A caterpillar is the larval stage of a butterfly or moth. It is a small, worm-like insect that feeds on plants and grows through a series of moults until it is ready to pupate, or transform into a butterfly or moth. Caterpillars are usually green, brown, or black in color and have a segmented body with short legs. They are important herbivores in many ecosystems and are also a food source for many other animals, including birds, reptiles, and small mammals. Some species of caterpillars are considered pests because they can cause damage to crops and gardens.