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"Buffalo Gnats" | Nature's Springtime Nuisance

Updated: Mar 17, 2021

Here in Illinois, spring weather is a welcome sight after a cold and long winter. It's finally time to get outside, hunt turkeys or mushrooms, head fishing, have a cookout or head to the golf course. Up until recently this was a pleasant time, minus the occasional mosquito buzz or sunburn. In the mid 2000's an overbearing new pest began showing up, the "buffalo gnat". If you've stepped foot outside in late April - early June, you have certainly witnessed the clouds of "gnats" as they swarm your face and body. Their relentless annoyance and the occasional bite has been known to drive people back into the house, to the store to buy gallons of vanilla scented spray or a head net. Many people want to know what these things are and where they came from.

David Blanchette | Jacksonville Journal-Courier

What Are "Buffalo Gnats"?

Buffalo gnat is a slang name for the black fly, with the moniker coming from their hump-backed appearance. There are more than 250 species of the black fly in the US and around a dozen are known to exist in Illinois. They are nectar feeding, aquatic insects. They are usually found near fast running water, where their eggs are laid, but they are known to travel up to 10 miles in search of blood. Only females bite, as they need a blood meal to produce eggs. They find their blood meal by sensing carbon dioxide expelled by respiration and body heat, a large reason that you generally find them in the most annoying place possible, your face. Those bites can be painful as they use scissor-like mouthparts to cut your skin and lap up the blood, similar to many other biting flies. This can lead to bumps, swelling and irritated skin for some. While they can seem to be everywhere, they can be avoided to some extent by avoiding activities at dusk and dawn, when they are most active. Fragrant shampoos or perfumes (except for vanilla) have been known to attract them as well, so skip the old spice this spring. On calm days they swarm and fly easily, however, they are not strong fliers. So, a nice breeze or a fan can hold them at bay. Long sleeves, long pants and a head net can keep them just far enough away to maintain some peace and avoid bites. Of course, insect repellants with deet can help and many have found vanilla based sprays to be effective as well, and safer to apply.

Where Did They Come From?

While common in northern states, black flies were not much of an issue further south until recently. There doesn't seem to any concrete evidence as to what caused the explosion in the Midwest, but there are a couple of theories that may point to the cause. Since these pests breed and grow in fast running, clear water it is thought that the tiling and efficient draining of agricultural fields may have something to do with it. With recent improvements in farm irrigation, there is less wetland and saturated soil and more moving water running into streams and rivers. This allows for perfect clean water breeding territory in the spring as creeks and waterways rise to higher levels and run longer with the consistent inflow from agricultural runoff. Another theory I came across was that potentially some flooding in the early 2000's caused eggs to dislodge from northern states and run downriver, setting the stage for a boom in black fly activity. No matter what caused it, they appear to be here to stay.

Are They Dangerous To People And Animals?

One positive is that so far, they are not known to transmit disease to humans. However, there have been a couple of deaths associated with possible allergic reactions. As far as animals, there are few reports claiming that the flies may transmit leucocytozoonosis, a disease of waterfowl and poultry. However, it usually is not the bite that is deadly but the nuisance itself. Livestock has been known to trample young and run into objects trying to get away from gnats. Turkeys and chickens can be suffocated from gnats clogging their nasal passages. If you own livestock, make sure to set up large fans in the spring to give them some relief. As far as wild animals go, there isn't much you can do other than watch for population decline and self-manage your wildlife.

For more information you can contact your state's department of public health.


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