Deer flies belong to the genus Chrysops and are smaller than horse flies. They 
are active during the hottest weather and are often quite abundant during rainy 
spells. More than 60 species occur in the Eastern United States. Diachlorus 
ferrugatus (F.) is acommon and notorious pest in swampy areas from New Jersey to 
Florida and Louisiana, especially in the Carolinas. 
Family Rhagionidae 
Snipe Flies 
Snipe flies are commonly found in the woods, especially in moist areas. The 
majority are brownish or gray; others are black with spots or stripes of white, 
yellow, or green. Both the adults and larvae feed on other insects. Adults of the 
genus Symphoromyia fly persistently about the head and are very annoying because 
their bites are painful. 
Family Asilidae 
Robber Flies 
Robber flies are mostly large to very large (fig. 214). Some have long, tapering 
abdomens; others are stout-bodied and resemble bumble bees. All are rather hairy. 
They are predacious on other insects and occasionally on their own kind. The larvae 
of Jolmerus notatus (Wiedemann), Leptogaster flavipes Loew, Laphria index 
McAtee, L. flavicollis Say, and L. thoracica F. have been collected from decaying 
wood infested with cerambycid and other coleopterous larvae. Larvae of certain 
other species feed on grasshopper eggs and white grubs. 
Courtesy Conn. Agric. Exp. Stn. 
Figure 214.—Adult of a robber fly, Asi/us sericeus. 
Family Bombyliidae 
Bee Flies 
These flies are moderately large, densely hairy, and look like bees. The adults 
are nectar and pollen feeders. The larvae of certain species are parasitic on the 
larvae of other insects, especially of the orders Lepidoptera, Hymenoptera, and 
Coleoptera. Others feed on the egg pods of grasshoppers. 
Family Empididae 
Dance Flies 
Members of this family are commonly known as dance flies because of their habit 
of flying in swarms—up and down, up and down—1in the woods, along streams, or 
446 
