Tuesday, July 10, 2007

Bee Fly

Bee Fly (Geron sp.)

Bee Flies in the genus Geron are among the smaller members of the Bee Fly family (Bombyliidae) found in the Ozarks region and look nothing like the Bumble Bee from which the family derives it's common name. They do have the hairy bodies and long, slender proboscis that are found in many family members, however. This particular Bee Fly was nectaring on an oxeye daisy during early June. While adults feed on nectar, their larvae are parasitoids or predators on bee larvae, particularly those solitary bees that lay their eggs in burrows excavated in the soil.

Some Internet sources say that when the female solitary bee goes in search of more leaves or pollen, the Bombylius female hovers at the opening of the burrow. While still hovering, she ejects an egg inside the tunnel with a flick of her abdomen. Maybe ... but I'll believe it when I see it. Another source notes that a female Bee Fly can sometimes be seen sitting in very loose soil, vibrating her butt like mad, so that the dirt is actually thrown outwards. I have seen something like this behavior, but am not willing to accept that she is gathering sand to coat her eggs so that they don't dry out, presumably so that she can chunk them down a solitary bee tunnel without harm. Instead, I accept that the female Bombylius is dipping her abdomen to oviposit, laying her eggs in the soil near a host species. When they hatch the larvae will feed on immature stages of beetles, bees, wasps, butterflies/moths, or on eggs of grasshoppers.