THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

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

These beneficial insects are predators on other insects, both as larvae and as adults. Most longlegged flies are terrestrial, but about a dozen aquatic or semiaquatic genera are widely distributed throughout the US. The aquatic species are almost exclusive to wetlands.

The long legged flies have only a few rods for a head, which distinguishes them from larval crane flies that have a fairly well developed head under the skin. The larvae usually have prolegs in the form of welts that extend around each abdominal segment, and a distinctive posterior "pit" or depression at the end of the abdomen that is surrounded by a few short lobes. When looking straight into the pit, you can see the spiracles with which they breathe air from the water's surface.