Caddisfly

Order Trichoptera — the caddisflies — contains about 14,500 species worldwide and is the closest living relative of moths and butterflies (sister group to Lepidoptera, both share a common ancestor in the Permian ~280 million years ago). Adult caddisflies look like small drab brown moths but with hairy wings (the order name Trichoptera means 'hair-wing,' versus Lepidoptera's 'scale-wing') and lack the coiled proboscis of moths. The most extraordinary biology is the CASE-BUILDING larvae. Almost all caddisfly larvae are aquatic and build portable cases from materials in their environment, glued together with silk produced from labial glands. Different species use different materials and architectures: Hydropsyche species build silk-lined retreats with capture nets; Limnephilus species build cylindrical cases of plant fragments; Glossosoma species build dome-shaped pebble cases attached to rocks; Helicopsyche species build snail-shell-shaped spiral cases of sand grains. The case provides camouflage, predator protection, and (in stream-dwelling species) ballast against current. The species' most-cited cultural moment is the 1980 work of French artist Hubert Duprat, who provided live caddisfly larvae with tanks of gold leaf, pearls, and precious stones — the larvae built cases entirely from these materials, producing functional case-larvae wearing real gold-and-pearl cases. The artworks have been exhibited in major museums and are a flagship case in art-and-nature collaboration. Adult caddisflies are nocturnal, drawn to lights, and drink nectar; mating swarms over streams in evening are a major fly-fishing trout food source.