EPOW - Ecology Picture of the Week

Explanation:   To bee, or not to bee?  This is not to bee.  Rather, it is not a bee.  It is a fly, belonging to the order Diptera (flies) rather than Hymenoptera (bees).  

Bee flies do not bite (but they do fly).  Adults feed on nectar and their larvae are parasitic on other insects.  Bee flies inhabit open and arid areas and visit flowers, hovering in mid-air, and alight with wings outstretched as shown in this photo.  

Most bee flies are stout-bodied and hairy and tend to resemble their namesake, bees.  But why?  One clue may come from when you catch them in a net ... they then buzz much like a bee.  This might be a case of Batesian mimicry, whereby this harmless organism mimics a more harmful one, thereby scaring away potential predators without having to invest the metabolic energy into producing venom and a stinger.  In fact, there are two other families of Dipteran flies that can appear like bees (Syrphidae and Asilidae).  An amazing convergence! 

Female bee flies may hover above crevices with nests of other insects, then swoop down and quickly drop an egg.  So like cuckoos and cowbirds in the avian world, this species is a nest or brood parasite, laying its eggs in the nests of other species.  In one case, a bee fly was reared from the cocoon of a Neodiprion sawfly.  

There are some 750 species of bee flies in North America north of Mexico.  

So the next time you go to swat a bee, pause and see if it isn't a harmless fly pretending to be someone else.