Yellow Fly Season! Are You Ready?


By Bernadette Canut, Public Outreach Coordinator And Amy Anguiano, Field Biologist

yellow flyIf Florida mosquitoes weren’t bad enough, yellow flies are here to steal their thunder. These devilish insects will begin to arrive around mid-April and normally stick around for six weeks. They are quiet flyers and are hard to hear approaching. Once the female yellow fly decides you are the perfect meal, she will gently land on you, and I am sure we are all very aware of what happens next. The female yellow fly is known as a fierce biter, and she will begin feeding on your blood by using her saw-like mouthparts to cut through the skin. I know it sounds horrible but just wait… there’s more! Once the cut is made, she will begin to lacerate the skin with her two pairs of cutting “blades.” This will allow the blood to flow out of the painful bite where she will then begin to “drink it up” with her sponge-like mouthparts. When this process is complete, the victim is left with a VERY painful welt which can take days and, worst case, weeks to go away. You might be asking yourselves at this point, “Where are the male yellow flies?” Great question! The males are non-biters and keep busy as pollinators and nectar feeders. So surprisingly, male yellow flies help us out with their pollinating abilities.

Yellow flies are most active on cloudy days or in wet, shaded areas near the edge of tree lines and avoid bright sunny, open areas unless they are extremely hungry. If you cannot avoid going outside, the best way to prevent bites is to stay covered. They are attracted to dark materials, so it is best to dress in bright clothing. Applying insect repellent containing DEET has had the best results.

Unfortunately, there does not seem to be an effective method to control populations, especially the larvae. Yellow fly kits can be used to reduce their presence in small areas or at least distract them from you but will not eliminate them.

Believe it or not, there is some good news when it comes to yellow flies! They do eventually disappear, and we can then turn our attention back to our dislike of mosquitoes!

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