caddis

Caddis, commonly referred to as caddisflies, are insects in the order Trichoptera. The aquatic larvae are renowned for building protective cases from silk and materials found in their surroundings, including sand grains, plant fragments, and small stones.

Adults resemble small moths: slender, with hairy wings held tent-like over the body. They are typically weak fliers and short-lived, with adults often feeding little or not at all.

Caddisflies undergo complete metamorphosis: egg, larva, pupa, and adult. Eggs are laid in or near water. Larvae hatch and construct individual cases, which provide camouflage and protection as they grow through several instars. Pupation occurs inside the case, and winged adults emerge to mate and lay eggs.

Ecology and significance: Caddis larvae are important components of freshwater ecosystems, acting as detritivores and grazers on biofilm, and in some species as predators. They inhabit streams, rivers, lakes, and ponds, often attaching to substrates. Because many species are sensitive to pollution, sedimentation, and temperature changes, caddisflies are widely used as indicators of water quality and ecosystem health.

Human use and cultural relevance: In angling, caddis larvae and cases inspire a range of artificial fishing lures. In research, their case-building behavior provides insight into material use, ecology, and habitat requirements of freshwater organisms.