Erax prolificus ( Osten-Sacken, 1887 ) 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 (Osten-Sacken) Osten-Sacken Osten-Sacken 1887 [151,589,1263,1290] Insecta Asilidae Carinefferia GBIF Animalia Diptera 36 37 Arthropoda species prolifica    Erax prolificus( Osten-Sacken, 1887): 202.   Recognition characters:Yellowish gray to brownish gray species; length 15–20 mm; mystax white mixed with some black and sometimes yellowish bristles; thorax mesonotum yellowish gray to brownish gray; dorsocentral stripe brown, narrow; crest formed of black setae subequal in length to antennal segments 1–2 with very few black bristles; anterior of scutellum with tuft of short, white setae; scutellum with short white hairs medially, long black bristles along margin; wings tinged with brown, costal vein dilated and subcostal vein black; male abdominal segments 2–4 black with mostly black setae, 5–7 white with white setae that are long and sparse laterally; female segments 2–7 black with black setae, venter 1–7 with erect white hairs, sometimes black on segment 7; legs with white setae and black and pale bristles, femora black with greenish metallic luster, tibiae red, darker apically, tarsi red.  Distribution:TETON: Grand Teton National Park, 18 Aug. 1931( LDA) (female specimen in CAS).  Habitat:Sagebrush steppe shrub and grassland vegetation type.  Ethology:Nothing known.  Prey:None known.