THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands
An Identification Guide and Educational Resource

This family is not commonly found in wetlands, but they are very common in Northwest streams and rivers. Only one genus of Lepidostomatidae is found in the Pacific Northwest (Lepidostoma), but there is a great diversity of species within that genus. The larvae of different genera look very similar, but differences in their preferences in case-building materials allows the species to be divided into a few ecologically significant groups. A few species can be easily identified, such as Lepidostoma hoodi, which has a distinctive round orange head and can be found in the western mountains from Oregon north to British Columbia.

Lepidostoma mainly feed on dead organic material, including leaves, other plants and dead fish. They tend to be sloppy eaters and generate a lot of waste, providing food for filter feeders such as black flies and netspinning caddisflies downstream. Most Lepidostoma live in cold headwater streams but some occur in the slower areas of larger rivers or on the edges of lakes.

Two key features that help separate Lepidostomatidae from other caddisflies are the location of their antennae and the humps on their first abdominal segment. Their antennae are tiny and located just at the front of their eye, and are often only seen as a light colored spot. Lepidostoma have lateral humps on the first abdominal segment, but lack a dorsal hump. Other cased caddisflies have both dorsal and lateral humps, with the exceptions of the humpless and tortoise case makers.