Species

Hover flies, also known as flower flies and Syrphid flies, belong to the order Diptera and the family Syrphidae, which contains more than 6,000 species.

Identification

Appearance
Hover flies have an average body length of 1-1.5 cm. There are two general types- some have medium to slender bodies and waists, resembling wasps, and others that have broad, hairy bodies with black and yellow bands on their abdomen thus bearing a strong resemblance to bees. They can be easily distinguished by their hovering flight and a false vein in their wings. Bees have four wings while hover flies have two.

Eggs are small (1mm in length), cylindrical, and white. Larvae can be cream, white, green or brown, without legs, narrower toward the head, and have tubes used for breathing at the rear.

Life Cycle

Females lay eggs in late spring/early summer one at a time on leaves and plant shoots in areas where the larvae will have quick and easy access to prey. The larval stage, the only stage that is predaceous, lasts around 8 or 9 days before they the larvae fall to the soil and begin to pupate. Complete metamorphosis from egg to adult can take 16 to 28 days.

Prey

Aphids
Thrips
Scales

Function

As previously stated, hover fly larvae are the active predators, not adults. The larvae, although blind, are voracious predators, especially of aphids as they are able to consume over 400 in their week long larval stage. They move along leaves seeking out prey and use a unique body part on their mouth that serves as a hook to first grab a hold of their prey and then to pierce the body. The larvae will then suck out and feed on the insides of their prey, leaving only the exoskeleton behind.

Some species are scavengers in decaying matter or can be destructive to bulbs (bulb fly).

Commercial Availability

Hover flies are not available for purchase.

Cultivation Techniques

While the larvae of hover flies prey on aphid and other soft-shelled insects, adult hover flies prefer to feed on pollen and nectar making them important pollinators.. This is also a common area where mating occurs. Having a variety of flowers and flowering plans will help to attract hover flies to your garden

Hover flies are most common in vegetable crops, gardens, and weedy areas. Plants in the daisy, mint and carrot families are particularly attractive to them.

References

"Identifying natural enemies- hover fly." 2006. Michigan State University IPM Program.
29 June 2008. <http://www.ipm.msu.edu/natural-enemies/flies-hover.htm>.

Metcalf, Robert. Destructive and Useful insects: Their Habits and Control. Mcgraw Hill, 1962. p. 66-67, 305.

"Natural Enemies Gallery: Syrphid, flower, or hover flies." 2003. University of Califronia Statewide IPM Program. 30 June 2008. <http://mint.ippc.orst.edu/syrphid.htm>.

Newton, Blake. "Flower Flies of Kentucky," 2004. University of Kentucky Department of Entomology. 13 Nov 2008. <http://www.uky.edu/Ag/CritterFiles/casefile/insects/flies/syrphid/syrphid.htm>.

"Syrphid Predator Identification." Oregon State University. 13 Nov 2008
<http://mint.ippc.orst.edu/syrphid.htm>.

Warner, Geraldine. "Syrphid Flies." 2008. Washington State University. 13 Nov 2008.
<http://jenny.tfrec.wsu.edu/opm/displaySpecies.php?pn=730>.