To Bee or Not to Bee

A bee-mimicking hover fly visits a flower in Argentina.

If you thought this was a picture of a bee, look closer.  A few key characters will give this mimic away.  Bulging, compound eyes take up most of the head.  The antennae are two short stunted nubs at the front of the head between the eyes.  The ‘waist’ or connection between thorax and abdomen is broad not narrow.  And most diagnostically, flies have only one pair of wings, not two — the hind wings being modified into two short knob-like structures used as counterweights in flight.  Thus the fly order name Diptera, “two wings” (two wings make up one pair).

This particular fly is a member of the genus Syrphidae, the hover flies or flower flies.  Many members of this group are bee or wasp mimics, as well as important pollinators of flowers.  As their name suggests, these flies are especially well adapted at hovering (aiding in flower visitation)  a skill which the males of some species use to impress females.  Such males stake out a spot in the air and attempt to remain ‘motionless’– an impressive feat for a tiny insect easily buffeted by wind currents.  The male who best holds his postion for the longest period of time is considered the sexiest.  The BBC series Life in the Undergrowth has an excellent segment on this behavior.