|scientific name Stenopogon inquinatus |
Dry forests, grasslands (sagebrush steppe in B.C.), gravelly river banks and sandpits. In Colorado it was found in wheat grasslands.
Adults have been observed from early June to early September (Cannings 1989).
Large (between 15 and 30 mm), heavy bodied, reddish species. There are two forms, one brown, and one more black. The brown form has a grayish yellow pollinose front and vertex. There is a very large gibbosity on the head (a hump). The antennae are either brown black or red black, and the mouthparts are full black. The thoracic colour is black, however it is covered with reddish brown humeri so it appear more brown. There are bristles present on botht the pronotum and episternum, but the metapleuron is bare. The legs are black on the coxae and dorsal sides of the femora, but have a reddish tinge elsewhere. Wings have an open posterior cell, and the anterior crossvein ends either at the middle or slightly before the discal cell. The abdomen is reddish brown on the middle, with black sides and venter. The pile is long on the first two segments, but is shorter on the following abdominal segments. The male genitalia is orange brown with black haris, and the female has lateral pits in the end of the eighth abdominal segment and black spines. The only difference between the brown form and the black form is the colour. The black form has black legs with reddish brown apices and black spines. In both sexes the eight abdominal segment is reddish brown with a black band around it. An intermediate form does exist, with black abdominal sides but a reddish brown narrow back. D. Macaulay image
This is perhaps the most common and widespread of the large robber flies in the dry forests and grasslands of southern B.C. Distribution may change as climate change increases grassland-steppe vegetation representation, however human disturbances have caused the destruction of much grassland habitats as well. Studies of overgrazed areas have revealed dense and healthy populations of Stenopogon inquinatus, suggesting it does not affect these asilids. (Cannings 1994)
Uses long raptorial legs to hunt other insects. Has been seen feeding on grasshoppers, dragonflies, and other robber flies.
Ranges from northeastern B.C. south to California and east to Manitoba and New Mexico. Common and widespread.
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