They are annoying, pesky, and won’t leave you alone. They look like little bees. Most people think they are sweat bees because of their black and yellow stripes but they don’t sting despite their extremely offensive behavior during the latter part of the summer. Regardless of their interactions with us, it is the covert interactions with the environment that make them standout insects in Illinois. Here are three things you didn’t know about Hover Flies:

1. Hover flies just want to lick your sweat. They land on us to drink our sweat. They cannot sting or bite but lick with and probe with their tongue. Hover flies are attracted to us because of the water from sweat and the salt on our skin. These late summer visitors have crashed our late summer activities leaving us swatting at flies. However, before you kill the hover flies know that they provide some great ecosystem services. 
2. Hover flies are prolific pollinators. Hover flies come in second to bees during pollination studies. Although they may not be prolific, they may be more efficient pollinators than bees. Bees collect pollen that is fed to their larvae and they are limited to their home ranges. Hover flies can carry pollen much further than bees. They also visit a greater diversity of flowers than the pickier bees.
3. Hover fly larvae control aphids in crops and our backyard gardens. The female hover fly will usually lay her eggs on or near aphid colonies and in two to three days the larvae will hatch. The larva, technically a maggot, is muted green to brown, legless, worm-like, and can be found on the undersides of leaves eating aphids, thrips, scale, caterpillars, and mealy bugs. These larvae are great garden warriors and can be put in the same category as ladybugs and lacewing larvae in terms of their effectiveness in demolishing an aphid population. The larvae grasp the prey with their jaws, hold them up in the air, suck out their body contents and toss the exoskeleton aside.

According to Cornell University, the larvae can eat up to 400 aphids. The larvae feed for about seven to ten days before they pupate. Therefore, if you see an aphid infestation in your garden, be sure to turn over the leaves to look for these beneficial maggots before you spray.

PHOTO CAPTION: Hover fly - Kelly Allsup, University of Illinois Extension; Hover fly larvae - Ken Johnson

ABOUT THE AUTHOR: Kelly Allsup is a Horticulture Educator for University of Illinois Extension serving Livingston, McLean and Woodford Counties. She meets the educational needs of her community, including local chapters of Master Gardener and Master Naturalist volunteers, through expertise in home horticulture and entomology. Her passion for ecologically-friendly gardening and all things plants makes her a dynamic speaker on topics that range from beneficial insects, growing vegetables and fruits, to urban trees.