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John Fulton

John Fulton
Former County Extension Director

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In The Backyard

Horticulture columns and tips done on a timely basis
Syrphid Fly
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Syrphid Flies, Sweat Bees, and Hornets

Posted by John Fulton -

Everyone seems to be having troubles with "sweat bees" these days. Or are they sweat bees? Sweat bees are about a quarter of an inch long, and are usually a metallic green in color. The yellow and black insects that are commonly called sweat bees are actually flies. Syrphid flies to be correct.

Syrphid fly is a generic name given to an entire group of flies. There are some differences in appearance and color, but the yellow and black color is the major one in our area. The other names for syrphid flies are hover flies or flower flies. They tend to hover around your arms and face when you have been perspiring, and land to lap up the sweat. They are also commonly found on flowers, hence the flower fly name, and do a good job of pollinating.

Syrphid flies are actually beneficial insects.They help pollinate, larvae feed on dead organic matter, and the larvae are predators of aphids.They cannot sting, but their mouthparts can usually be felt when lapping up sweat from sensitive areas. You may feel a slight pinch.

Yellowjackets are the other common yellow and black insect this time of year. Yellowjackets can be very aggressive in biting and stinging. They are usually about twice the size of the syrphid flies, and the easiest way to tell them apart (without getting stung) is to count the wings. Flies have one pair, and bees and wasps have two pairs.

Yellowjackets are most frequently encountered when they scavenge for food. Their habit of feeding on nectar and sugar can create a nuisance. Yellowjackets are attracted to open cups and cans of soda and other sweet liquids. They are also attracted to open cans of garbage, bright flowery clothing, and floral scented perfumes. All outside garbage cans must be kept clean and well covered, to reduce yellowjacket problems. Contact with the wasps can be decreased by reducing these attractions at picnics and other outings. In situations closer to home, the elimination of overripe fruit from gardens and orchards will dramatically decrease the number of scavenging yellowjackets. Holding gatherings indoors and using screens on windows will also help avoid yellowjacket problems.

There are a variety of traps on the market that claim to attract yellowjackets. These traps are baited with the scent of rotting fruit or other odors equally as appetizing to the yellowjackets. It is questionable whether these traps can out-compete the natural and man-made attractants described above. However, it is certain that through proper sanitation and removal of natural and man-made attractants, yellowjacket contact can be reduced. However, in situations where the potential for repeated contact exists, other management methods may be necessary. These traps can also attract more yellowjackets if placed close to the home or patio, so place them to attract the insects away from where you'll be.

As for the syrphid flies, no controls are going to be very effective. On the other hand, there really isn't much need for control. They are really a nuisance pest that is very agile. They will probably be able to avoid that aerosol spray. Inside the home, a swatter and a vacuum cleaner are probably the best tools.

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