Buffalo Gnats / Black Flies
Dog-day Harvest Fly
Fruit and Gall Flies
Gad Flies / Horse Flies
Grass Stem Flies
Little Fruit Flies
Salt Water Flies
Thick Head Flies
Insect guide > Flies > Bee Flies
The handsome, stout-bodied, active flies of this family are commonly known as "bee-flies" from their superficial resemblance to bees. There are over 1,400 species known. They usually have spotted or banded wings and their bodies are clothed with hair. They poise in the air in their flight and are most frequently found in sunny openings in the woods.
They are distinguished from allied flies by the characters mentioned, by their venation, slender legs, small, close three-jointed antennae and rather long proboscis. They are distinctively flower-flies, frequenting blossoms and feeding upon the pollen and nectar which they are able to reach with their long beak. Some of them somewhat resemble the gad-flies of the genus Chrysops, and others, like Systropus have a slender abdomen swollen towards the tip and look like mud-dauber wasps.
Their larval habits are extremely interesting and they are parasitic upon wild bees and in the egg-cases of grasshoppers as well as upon certain caterpillars.
On the whole they may be termed beneficial insects.
Typical Life History of a Bee-Fly
(Systaechus oreas O. S.)
This species is a Western form and is parasitic in the egg-cases of the so-called Rocky Mountain Locust or Western Grasshopper. It is unfortunate that the life history of no good representative of the Eastern species in some one of the other genera which may be supposed to live in the nests of wild bees has been worked out. Here is a field for some intelligent Eastern worker. The eggs of the present species have not been observed but the larvae are found in the egg-pods of the grasshopper or near them and of different sizes during most of the year. The larvae begin to transform to the pupa state early in the summer and the pupa pushes itself half-way out of the ground in order to disclose the fly.
Flies continue to issue during the summer. Normally there is but one generation annually but there is a great tendency to retardation and sometimes the larvae remain over unchanged until the second year.
The larva is a stout, plump, curved, grub-like looking creature with an opaque whitish color with small dark-brown head. The pupa looks something like the pupa of a Lepidopterous insect but bears many spines on the head and thorax and the dorsal ridges of the abdominal segments also bear rows of spines while other portions of the body carry soft dark hairs.