Caterpillar, larval stage of butterflies and moths, members of the order Lepidoptera, and corresponding in this special order to the grub, maggot, or larva phase in the life history of other insects. The caterpillar develops like any other larva from the segmented egg and differentiating embryo and undergoes several moltings, or ecdyses. It later falls into a quiescent pupa stage, and the pupa is usually
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sheathed in a silken cocoon. It may be fixed or free, suspended by one thread or more to a leaf or branch, or hidden underground.
Comparatively few caterpillars reach maturity. Many are destroyed by weather; by birds, reptiles, and other animals; and by insects such as ichneumon wasps, tachinid flies, and ground beetles. Ichneumon wasps pierce the caterpillars and make them receptacles for their eggs and, later, edible cradles for their larvae.