THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

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

Psychomyiids build fixed, tube-like retreats from silk and sand grains. Although their tubes are fixed, they aren't necessarily stationary. After the nettube caddisflies eat the algae in front of their shelter, they build on to the front for protection while accessing fresh substrate for grazing. In this fashion, they move their shelter slowly around the substrate, grazing as they go.

The larval nettube caddisflies are distinguished by their hatchet-shaped foretrochanter (a hard appendage at the base of the front leg) and their long anal prolegs. They do not have a plate on the top of the second and third thoracic segments, or on the ninth abdominal segment.