Sunday, June 12, 2011

Cylindromyia fly: an incredible mimic


On a recent excursion into Indiana's Hoosier State Forest - yes, they have trees over there - I happened to glance at this oxeye daisy and notice a weevil. I like weevils. These beetles remind me of tiny elephants with their trunklike proboscis, so I swiveled the macro lens in its direction. No sooner had I drawn a bead when another even more interesting creature alit on the weevil's flower, even having the temerity to step on my subject.

I must admit, my first thought was "wasp!" followed by "this might be good!". My initial childish hope was that the "wasp" might attack or otherwise engage the beetle, giving me some real action photos. But all of that flitted through my mind in just a second or so, as the reasoning part of my brain worked at digesting what was really going on.

But it didn't take long to realize that this was no wasp at all, but a remarkably good wasp mimic.

It is, I believe - and as always, someone please correct me if I am wrong - a species of tachinid fly in the genus Cylindromyia. A giveaway that this is actually a fly is the single pair of wings - non-flies such as wasps have two obvious pairs of wings. In flies, the second pair of wings are greatly reduced, and called halteres. The Cylindromyia's halteres are whitish, and visible behind and at the base of the primary wings.

Also, our wasp-fly has stiff hairs projecting from its body - a very tachinid fly-like feature, and the field mark that put me in the right arena in regards to trying to figure its identity. Looking like a stinging bad guy probably helps the fly survive the predation dangers that come with visiting flowers for nectar.

The Bug World is absolutely full of this sort of mimicry; an endlessly fascinating subject.

1 comment:

Janet Creamer said...

Awesome fly and you taught me a new word-temerity. :)