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Saturday, August 27, 2005

Hover flies, humble members of the Order Diptera

Flies, members of the insect order diptera, are burdened with the bad reputations of some of their members. Mosquitos are flies; tsetse flies are flies; house flies are flies. But there are around 80,000 species of diptera worldwide, and the life histories of these creatures are varied and not all evil or even annoying. Many of them are what we humans regard as beneficial. (Bear in mind that on a happy day I consider house flies beneficial in that they provide food for spiders.)

During summer, the many species of hover flies (family Syrphidae) visit flowers to feed on nectar and pollen. They are one of the most prolific pollinators, but are often taken for bees, which they mimic in color and form. Here are a few of the species I observed in the past few weeks.

Syrphids may look something like bees, but they distinguish themselves by (among other things) having two wings instead of four, shorter antennae, and the ability to hover motionless. You'll see bees that may be small like syrphids, but they dart or bumble from flower to flower while the flies exhibit amazing aeronautic abilities.

Notice that two of these photos show the fly with the same flower---tanacetum vulgare or common tansy. It's a magnet for bugs of all sorts but especially flower feeders.

Syphid fly larvae (the stigmatic "maggot" is the term for fly larvae) eat aphids, so whatever you can do to encourage syrphids to like your garden or yard will pay off in free aphid control.

6 comments:

Hypatia said...

Ah... now I see. A kindred spirit. :) Nice to meet a fellow bug girl.

I was just out near Tustin for a wedding.

We just released some painted lady butterflies too. Cosmic unconsciousness strikes again.

JustAGirl said...

Lovely photos and very interesting site.

sirbarrett said...

Well, these are nice little flies, not the pesky, buzzy, house flies. I admit that all flies are useful for something, but black flies and horse flies are the ones I steer clear of. Their bite hurts a lot!

Anonymous said...

I think that you need to tell people why they are BAD instead of why they are good! AMANDA~

Anonymous said...

Not all inscects are good...tell us why they are bad too...

vanessa cardui said...

Anonymous: I am not aware of any bad (from a human perspective) qualities of hover flies. Their larvae consume pests (aphids), the adults help pollinate flowers and are pretty. When an insect or spider has a quality detrimental to humans, I usually do mention it.