Monday, July 26, 2010

That's no bee!

This bee mimic was foraging on tiny thistles in the Reifel Island bird sanctuary.

A syrphid fly, probably*.

It's cheating: to simulate bees' antennae, it holds two legs out in front of its head. And it's about the size of a bee, and furry; any bird that skips bees will pass this one by, too.

A bee has four wings. A fly, like this one, has two. Birds aren't supposed to notice this.

Bees have nicely rounded abdomens; syrphid flies' bellies are so thin they look squashed. This one curves downward at the back, so it looks fat from a bird's eye view. From the side, however, the fakery is exposed; that belly is flat!

Notice the unusual shape of the wings; scalloped at the rear end.

I was fooled, too, at least until I got home and looked at the photos. I have advantages a bird doesn't, even with their superior eyes.

* A similar one, from Ontario is here, on BugGuide. Ours is probably in the same Subfamily, Eristalinae.

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aka Penelope said...

Very interesting post. It has made me wonder if the bee in my photo is a pretender. :))

Clytie said...

Wow, I never would have guessed! When you point out all of the clues, I see the differences ... Thank you for the education!