Flower flies - mimicking bees in more than one way.

Sphaerophoria - flower fly common in Alberta

 Flower flies, also known as hoverflies, are common throughout North America.  The one above was photographed in eastern Alberta.  Their name comes from their fondness for pollen and nectar, something they have in common with bees, and for their ability to hover effortlessly in one place for extended periods of time.

This particular genus (Sphaerophoria) is also a bee mimic.  The black and yellow abdominal stripes are reminiscent of their sting-equipped cousins.  Although harmless, would-be predators often give it a wide berth because of the risk of incurring a violent physical and chemical assault.  Mimicry is a common practice in nature where a defenseless organism (the mimic) gains some protection by posing as another species (the model) with serious defensive capabilities.  Usually, a colourful display warning predators off is involved.

It turns out that many flower flies have other attributes that make them valuable crop and garden insects.  The adults, in their search for food, end up being pollinators.  If you examine the above photo you will notice the fly is covered with quite a bit of pollen.  As they move from flower to flower they facilitate pollination.  Although bees are, without a doubt, the most important insect pollinators, hoverflies contribute significantly.

Flower flies bring other benefits to the table.  Those belonging to the genus Sphaerophoria are carnivorous as larvae (maggots) and feed heartily on a host of pests including aphids and scale insects. Unlike the Hymenoptera as a whole, the flowerfly larvae live independently and have to forage meals on their own.

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