Bee or fly?


It is spring and buzzing abounds as pollinators visit flowers. 

If one follows the news media, it is tempting to assume that those pollinators are bees, and in particular, honeybees. Actually, in many cases, they are either bumblebees or are flies. (I have seen no honeybees in my yard so far this spring.)

Indeed, most of the pollinators I have noticed are flies — but, flies that look remarkably like bees. Many are bee mimics. They perform this subterfuge to trick birds into leaving them alone. A bird can find a bee painful to capture, and so will generally also avoid something that looks like a bee.

Despite the fact that many birds cannot easily distinguish a stinging bee from a tasty fly, human observers can. What are the clues?

Bees have small eyes and long antenna; Flies have big eyes and short antennae. (OK, bees also have four wings while flies only have have two — but in the field the wing differences are difficult to spot.) 

A bumblebee (a Bombus bifarius) visits a flower. It has small eyes and long antennae. 

A similar looking fly (a Criorhina sp.) visits the same flowers. It has big eyes and short antennae.


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4 Responses to Bee or fly?

  1. birthe says:

    The wings on the fly look longer. Could that be another clue, or is it just an illusion because of the way the photo was taken?

  2. Neville Maytom. says:

    This is an example of mimicry in nature. The fly is very likely protected from predators, as the latter are unable to differentiate the edible fly from the less desirable bee/bumblebee.

  3. Neville Maytom. says:

    My apologies Alistair, I missed the reference to mimicry in your write up.

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