Trichoptera

Trichoptera, commonly known as caddisflies, are an order of insects closely related to Lepidoptera (moths and butterflies). They are found worldwide, especially near freshwater. Adults are short-lived and mostly nocturnal; larvae are aquatic and develop in streams, rivers, lakes, and ponds. A hallmark of many species is the use of silk to build protective cases or nets.

Adults resemble small moths with two pairs of hairy wings held roof-like over the body, long antennae, and often reduced mouthparts. Larvae are aquatic, caterpillar-like, and many construct protective cases from silk and ambient materials such as sand, plant matter, or stones. Other larvae live in fixed retreats or nets.

Trichoptera undergo complete metamorphosis: egg, larva, pupa, and adult. Eggs hatch in water; larvae molt through instars and pupate inside a case or cocoon. Adults emerge, mate, and females lay eggs; adults live only briefly.

Ecologically, larvae perform roles as shredders, grazers, filter feeders, or predators, contributing to leaf-litter breakdown and energy flow in freshwater ecosystems. Many species are sensitive to pollution, making them valuable bioindicators of water quality.

Historically, Trichoptera has been divided into three suborders: Annulipalpia (net-spinners), Integripalpia (case-builders that use portable cases), and Spicipalpia (various early lineages). Most species belong to numerous families totaling thousands of described species.

Caddisfly larvae produce silk used to build cases and nets, and their presence is widely used in freshwater biomonitoring due to sensitivity to pollutants. Habitat loss and water pollution threaten many species.