caddisflies

Caddisflies are insects of the order Trichoptera. They inhabit freshwater environments as larvae, while adults are terrestrial and usually short-lived. The larval stage is notable for its cases, which many species fashion from silk and assorted surrounding materials. Adult caddisflies resemble small moths, with hairy wings held tent-like over the body when at rest. They typically have long antennae, and many species feed little or not at all after emergence.

Larvae are aquatic and diverse in feeding strategy. Case-making species construct portable shelters from silk and incorporated materials such as sand, pebbles, plant fragments, or other debris. Net-spinning species build silken nets in flowing water to capture food particles. Most caddisfly larvae feed on detritus, algae, or small invertebrates. The protective cases aid in camouflage and predator defense, while materials reflect local substrate conditions and habitat quality.

Lifecycle and habitat considerations: Caddisflies undergo complete metamorphosis. Eggs are laid in or near water; aquatic larvae hatch and grow through several instars, often pupating within the case or a nearby retreat. Adults emerge from the water, mate, and females lay eggs on or near moist surfaces. Distribution is worldwide, with greatest diversity in clean, well-oxygenated freshwater systems. Many species are sensitive to pollution and sedimentation, making them useful indicators of water quality.

Ecology and human relevance: Caddisfly larvae contribute to detrital breakdown and nutrient cycling and form a major part of fish diets. Their presence supports healthy freshwater ecosystems, and they are commonly used in ecological assessments and, in angling culture, as sources for natural fishing lures.