Caddisflies belong to the order Trichoptera, which means “hairy winged,” and suggests its close relationship with lepidoptera (the moths and butterflies). The caddisflies make up one of the most diverse and conspicuous orders of aquatic macroinvertebrates. The immature form of many species create protective cases out of rocks, sand grains, plants, sticks or other found objects. One genus in the family helicopsychidae was initially identified as a snail because it creates a coiled case! Caddisflies are very good indicators of the condition of aquatic habitats, because they are common, speciose, and often have very specific habitat requirements.
Caddisflies are essential components of aquatic food chains, eating both plant and animal material, and acting as an important food source for fish and other animals. Because caddisfly larvae, pupae and adults are all eaten by fish, they are well-known to people who fish.
The Xerces Society works to protect rare caddisflies, such as Susan’s purse-making caddisfly, through the Endangered Species Act and public education. We also use caddisflies and other aquatic invertebrates as indicators of the condition of a particular aquatic habitat – understanding the biological integrity of a river, stream or wetland is the first step to protecting it.