OBSERVATIONS ON THE BIOLOGIES AND DISTRIBUTION OF CERTAIN PACIFIC NORTHWEST SHORE FLIES (DIPTERA: EPHYDRIDAE)

Mt. Rainier National Park was extensively surveyed for ephydrids in 1977, 1978 and 1979. Nine ephydrid habitat types sampled included: moist meadow (with 26 species); wet woodland (13); montane seep (5); sedge meadow (17); mud shore (29); stream rocks (7); glacial river bed (3); sand shore (29); and roadside ditch (23). Four species were also found associated with flowering Anaphalis margaritacea. A total of 59 species representing 22 genera were collected. Results of the survey, habitat distribution, abundance, isolating mechanisms and general biological information are presented.;Adults of Paracoenia bisetosa are common on algal mats and limnic wracks from March to November, while their immatures may be found as early as April. Courtship behavior is relatively simple and similar to many other ephydrids. The egg-to-adult period ranged from 13 to 26 days, allowing for six generations to occur during the season.;Setacera needhami adults occur in the algal mat habitat from February to June and September to November. Immatures are most abundant in the late summer. Courtship behavior also appeared simple. The egg-to-adult period varied from 15 to 26 days. S. needhami may have four to five generations, with two occurring in the spring and two or three during the late summer.;Scatella paludum, one of the most common northwest shore flies, is often found in large numbers within the sand and mud shore habitats from April to September. Overwintering occurs in the adult and pupal stages, or either. Courtship is similar to other species of Scatella. In eastern Washington the species may produce six or more generations each year.;The biologies of three species common to eastern Washington are discussed and the immature stages of each are described and illustrated. Paracoenia bisetosa and Setacera needhami were studied in the Potholes area (Columbia National Wildlife Refuge) of east-central Washington, while Scatella paludum was observed in the Snake River canyon of eastern Washington.