The Hoverfly

Bee MimicThis hoverfly is backlit through a grape leaf. It was kind enough to stay still while I moved my camera within inches of it to capture these images. For the most part, hoverflies are camera shy as they flit from one flower to another feeding on nectar, pollen or both. Many species of hoverflies, in either the larval or adult stage, consume aphids, playing a significant role in controlling this pest’s population.

Hoverfly

The name hoverfly encompasses a large family (Syrphidae) of flies containing some 6,000 species. Other common names include flower fly and syrphid fly.

With so many varieties within this family, it is difficult to identify a specific species, or sometimes even figure out the genus. Most species of the Syrphidae family contain black and yellow stripes on their abdomen, however other coloration and body patterns exist as well.

The banding often works to be an advantage to the flies as it allows them to mimic bees and wasps, and therefore ward off predators. Many species go to great lengths to convince us that they are bees. Some have developed a narrow waist similar that that of a wasp.  Some hoverflies are even able to imitate the buzz of a bee. Others impersonate bees by feigning a sting by thrusting the tip of their abdomen towards a threat they have landed on. Bristly hairs also add to the illusion in many cases. Despite the perceived threat, hoverflies are harmless. A dead give away in distinguishing the the mimic from an actual bee or wasp is the wings. Bees and wasps have two pairs of wings, whereas hoverflies as well as other flies have only one pair.

The abdominal striping is not exclusive to Syrphidae, but is is a good indication that you may be looking at a hoverfly. The ability to hover in one place, is a specialty of Syrphidae, making it another good indicator. But there are flies in other families that can fly in one place.

 Hoverfly Wing LabelsA careful examination of the wings can easily confirm or discount the identification as a hoverfly. However this method is not always practical when observations are done in the field, as magnification and a fly that will hold still for you are both required to see the details clearly.

The first feature that is almost exclusive to all hoverflies is a vein that fades before making a connection (A). This is called the spurious vein. Typically a vein ends either by intersecting with another vein or with the edge of the wing itself.

Another distinctive vein feature is the vein that runs along the bottom of the wing toward its outer tip. In most flies, this vein reaches the tip of the wing without conecting to another vein. In hoverflies this vein intersects with another vein before connecting with the wing’s edge (B).

If both these wing characteristics are present, the identity is verified to be that of a hoverfly.

Taking a macro photo and closely examining it, is a good way to implement this identification technique.

More detailed information can be found at All About Hoverflies.

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5 Responses to The Hoverfly

  1. Thanks for a great post! I learned a lot and the difference in the number of wings between hoverflies and bees is especially helpful, much like knowing the open / closed wing positions of dragon and damsel flies.

  2. Hi, Rick! I was so happy to see your Gravatar and recent comment on my blog. I’m delighted to see this fascinating post about hoverflies, and these wonderful photographs. I was offline for a bit, and must have missed it when you first posted it. Happy New Year!

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