Bagworm, common name for the caterpillar of any of several species of bag-weaving moths of the psyche family. The name is applied especially to the common bagworm of the eastern United States. The caterpillar spins a protective silken bag into which it weaves pieces of leaves and twigs and which it carries about attached to its abdomen. As the larva grows, it enlarges the bag, and when ready to pupate, fastens the bag to a tree branch and undergoes metamorphosis inside it. In about three weeks the adult male emerges and sets out on the mating flight. His wings are dark at first but later become transparent. The wingless female continues to live inside her bag, which later becomes a receptacle for her eggs. Another species of bagworm is more frequently found in the southern United States, where it lives on citrus trees.
Scientific classification: Bagworms belong to the family Psychidae, order Lepidoptera. The common bagworm of the eastern United States is classified as Thyridopteryx ephemeraeformis. The species common in the southern United States is Oiketicus abbottii.