Williston, 1893b: 75 Robber flies (Insecta: Diptera: Asilidae) of Wyoming, USA with keys to genera and species Lavigne, Robert J. Dennis, Steve Zootaxa 2019 2019-08-30 4662 1 1 126 (Williston) Williston Williston 1893 [151,609,1725,1752] Insecta Asilidae Proctacanthella Animalia Diptera 55 56 Arthropoda species leucopogon     Asilus leucopogon  Williston, 1893b: 75.   Recognition characters:Brown species; length 15–16 mm; mystax white; thorax brown pollinose; scutellar setae and bristles white; wings hyaline; abdomen brown pollinose; male genitalia without white pencil of setae, legs similar to  P. cacopiloga; females can be separated on the basis that all setae on the underside of the first antennal segment are white in this species whereas in  P. cacopilogasome are black; female  P. leucopogonalso have light colored setae/bristles dorsally on the hind tarsi (  P. cacopilogahave dark setae).  Distribution:BIG HORN: Lovell, WANG, LTA, 7 Aug. 2004( CSU, GMAD). CONVERSE: Glenrock, Dave Johnston Plant, 6, 13 July 1974( RJL). FREMONT: Lander, WANG, LTA, 8 Aug. 2004. GOSHEN: Fort Laramie, 24 July 1958( DRT); Goshen Co., 12 July1943( REP), 21 July 1944( REP); Torrington, 18 July 1960( DGF). LARAMIE: Pine Bluffs, 1 Aug. 1962( RJL), 3 July–3 Aug. 1963( LJS). NIOBRARA: 64 kmN of Lusk, July 1895( RM-UK). PLATTE: Camp Guernsey, WANG, 2001b ( CSU, GMAD); Chugwater, 23 July 1952( REP); 24 July 1953( REP); Dwyer, numerous records, 23 June–17 Aug.( RJL); Guernsey, numerous records, 6 July–1 Sept.( RJL); Register Cliff, 15 July 1964( RJL); GuernseyState Park, 16 July 1964( RJL); Hartville, 17 Aug. 1963, 7 July 1964( RJL), 9 Aug. 1964( RJL); Platte Co., 2 Aug. 1945( REP); Wheatland, 5 Aug. 1964( RJL, FRH), 27 July–25 Aug, 1965 ( RJL), T25N R67W S27, 6July 1974 ( RJL). WESTON: Newcastle, 11 kmS, 11 July 1980( RJL). Recorded from Wyoming by: Dennis et al.(2010); Geller-Grimm (2018); Lavigne & Dennis (1994).  Habitat:Saltbrush-greasewood shrub, wheatgrass-needlegrass shrub steppe shrub and grassland, and gramaneedlegrass-wheatgrass, grama-buffalo grass and wheatgrass-needlegrass grassland vegetation types. Protected gullies both with and without pine cover on the short grass plains area; rangeland.  Ethology:Rests on and forages from soil and vegetation, depending on substrate temperature (see Rogers & Lavigne 1972).  Prey: DIPTERA, Culicidae:  Aedessp.; HEMIPTERA (Heteroptera), Geocoridae:  Geocoris pallensStål, GuernseyState Park, 16 July 1964. HYMENOPTERA, Halictidae:  Halictussp. (two records) ( COLEOPTERA, DIPTERA, HEMIPTERA (Heteroptera, Homoptera), HYMENOPTERA, ORTHOPTERA(see Dennis et al.2010; Lavigne & Dennis 1994; Rogers & Lavigne 1972).