Pupa is a stage between larva and adult in the life of some insects such as butterflies, beetles, flies, ants, and bees. Depending on the species, the inactive pupa is protected by a hard shell, silk cocoon, camouflage, or other means. Pupae undergo a complete metamorphosis and emerge as adults within weeks or months in most species. The pupal stage of butterflies (chrysalis) occurs on trees, which makes it the most familiar. However, most insects pupate in underground cells.