PROC. ENTOMOL. SOC. WASH. 86(4), 1984, pp. 749-759 SHORE FLY (DIPTERA: EPHYDRIDAE) COMMUNITY STRUCTURE IN A XERIC GRASS HABITAT Bruce A. Steinly Department of Entomology, University of Illinois, 320 Morrill Hall, Urbana, Illinois 61801. Abstract.— Analysis of a xeric terrestrial grass shore fly population found the community composed of 1 7 species. In addition to the 14 species previously listed from southern Ohio terrestrial grass, Parydra breviceps Loew, Hyadina binotata (Cresson), and H. pruinosa (Cresson) were collected. Leptopsilopa atrimana (Loew) was dominant during the collection period. The consistent presence of L. atrimana adults and gravid females suggested the species has encountered physical and biological conditions satisfying minimum reproductive requirements. Quantita-tive parameters including species diversity (H'), evenness (J'), richness (s), and relative abundance (RA) were calculated for xeric terrestrial grass. A comparison of terrestrial quantitative parameters with aquatic grass shore and limnic wrack suggests fundamental differences in species composition. Also, low indices of similarity in addition to physical and biological observations substantiate the designation of xeric terrestrial grass as a new shore fly habitat. The Ephydridae are considered one of the most diverse families of cyclorraphous Diptera. Of the 404 Nearctic species (Deonier, 1979), most are semi-aquatic as adults and aquatic in the immature instars. Adults are frequently found in wetland habitats, and many species survive the rigors of thermal springs (Brues, 1932; Tuxen, 1944; Wirth and Mathis, 1979), alkaline springs (Brock and Brock, 1968; Lindroth, 1931; Wirth and Mathis, 1979), inland saline pools and lakes (Aldrich, 1912; Ping, 1921; Scheiring and Foote, 1973), coastal sah marshes (Dahl, 1959; Simpson, 1976a), crude oil pools (Crawford, 1912; Thorpe, 1930), and urine-soaked wood (Oldroyd, 1964). Additionally, several unusual larval microhabitats have been reported. Larvae have been collected under a human cadaver and pig droppings (Bohart and Gressitt, 1951), reared from decaying crayfish (Runyan and Deonier, 1979), and marine mussels (Steinly and Runyan, 1979), associated with decaying land snails (Berganstamm, 1 864), reared from aquatic snails (Wirth, 1971), preying on the developing eggs of a marsh-inhabiting spider (Becker, 1 926; Scheiring and Foote, 1973), developing frog eggs (Bokermann, 1957), and mining leaves (Meijere, 1947). Although these microhabitats were unusual, the shore flies were located in close proximity to aquatic or marine habitats. The first comprehensive ecological, distributional, and behavioral investigation of the Ephydridae was accomplished in Scandinavia (Dahl, 1959). Later, Deonier (1965) reported the results of his studies on the ecology and distribution of the Iowa fauna. Deonier (1965) collected more than 100 shore fly species from 12
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