This is a large robber fly which is approximately .75-1.5 (20-35 mm) inches in length. Females are larger than males. This fly has black eyes, a light colored “beard” on the face and a brown thorax. The long, cylindrical abdomen is cream colored with thick, black cross-bands. The abdomen has a black tip. The wings are clear and brown, and do not reach the end of the abdomen when the fly is at rest. The legs are reddish-brown and hairy.
It is the most common robber fly in our area and seems to be most numerous throughout the month of August.
This robber fly is a ferocious predator. When it flies up from its perch, it makes a loud buzzing noise. The larva burrows into soil and feeds on insects, roots and decaying matter. It pupates in an unlined cell in the soil. There are 21 species in the genus Promachus in North America.
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