Life History Caddisflies are holometabolous insects whose eggs are deposited in gelatinous matrices in or out of water. Most species are univoltine, but some complete more than 1 generation per year, whereas others requi re 2 years for development. The pupal phase is generally 2 to 3 weeks, although some species may overwinter as pupae. Many caddisflies undergo a diapause phase, which, depending on the species, occurs in one of several life history stages. Pupae have func tional mandibles that they use to chew their way out of the pupal case once they are ready to emerge as adults.
Adults are mostly crepuscular, limiting their activity to dusk or darkness.
Adults live from a few weeks to several months, depending on the sp ecies and the nature of the habitat. The larvae of some leptocerids are re ported to damage the young shoots of rice plants in paddy fields. The larvae of a few species are known to eat fish eggs. On the beneficial side, many hydropsychids prey on black fly larvae. Many species that inhabit temporary ponds lay eggs in the basins of dry pools in the fall, when the soil surface is beginning to become more moist.