Caddisflies have extremely soft bodies in need of protection. As such, caddisflies may form casings from twigs and other hard plant materials leading people to sometimes call them stick caddisflies. They may also use abandoned snail shells, which they adhere to themselves with saliva. After a stick caddisfly has completed its casing, it is often difficult to identify it as an insect. The only indicators that a stick caddisfly is not an inanimate twig are its head and legs.
Stick caddisflies typically live near slow-moving bodies of fresh water and help in maintaining the balance of the aquatic ecosystem. Stick caddisfly larvae act as a food source for fish and feed on zooplankton, which live near the mouths of rivers and along the perimeters of lakes. Stick caddisflies cannot survive in polluted water; large populations typically indicate healthy, balanced environments.