Along with mayflies and stoneflies, caddisflies can be important bioindicators of water quality. Most Trichoptera species won't tolerate changes in environmental quality of the river and streams where they live. The order name comes from the Greek trichos for hair, and pteron for wing.
Description:
Adult caddisflies look similar to some moths, at first glance. Look closer, however, and you'll see membranous wings covered with setae, not scales. A caddisfly's body is usually hairy as well. Caddisflies have long, slender antennae, Most are drably colored, but some have distinct wing markings. Caddisflies are nocturnal, and often attracted to lights.
Caddisflies undergo complete metamorphosis. Adults attract mates using sex pheromones. Mated females deposit eggs on the surface of lakes, ponds, or streams, or dive below the surface to cement them on submerged rocks or plants.
Caddisfly larvae bear a resemblance to caterpillars, but have a distinct head and well-developed legs on the thorax. Many caddisfly species are casemakers, and each kind builds its own characteristic case. The larvae produce silk, which they use to fashion a portable shelter from pebbles, sand grains, plant materials, twigs, or other materials. Other caddisflies construct nets, which they use to catch food as it flows downstream. Some predaceous caddisfly larvae live freely, without the encumbrance of nets or cases.
Case bearers seal themselves inside their cases when they're ready to pupate. The pupa chews its way out of the case, swims to the surface, and crawls from the water before the adult emerges.
Habitat and Distribution:
Most caddisflies require cold, clean water in which to live. Degradation of the stream or river results in a drop in the caddisfly population, making these insects excellent bioindicators of water quality. Caddisflies exist throughout the world, with over 7,000 species known.
Major Families in the Order:
- Family Hydropsychidae - netspinning caddisflies
- Family Limnephilidae - northern caddisflies
- Family Phryganeidae - giant casemakers
- Family Hydropsychidae - netspinning caddisflies
- Family Brachycentridae - humpless casemaker caddisflies
Families and Genera of Interest:
- Heteroplectrom larvae construct cases by tunneling through a stick, lengthwise.
- An Oregon species, Philocasea demita, lives in wet leaf litter as larvae.
- The wings of Dolophilodes distinctus females form according to the season. Warm weather emergents have normal wings, but winter emergents form only vestigial wings.
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