STARKVILLE, Miss. -- Increasing buffalo gnat populations are more than a nuisance to central and south Mississippians; they cause measurable, sometimes fatal harm to chickens and livestock.

Swarms of these insects, also known as black flies, are killing backyard chickens and causing headaches for small-scale poultry producers in central and south Mississippi. At about 3 millimeters long, buffalo gnats breed in flowing water, so outbreaks tend to be in areas near rivers or streams.

Jerome Goddard, an entomologist with the Mississippi State University Extension Service, said these insects are also staying active for a longer time. Buffalo gnat season has expanded from a few weeks a year in the early spring to a three-month window between early April and late June, with some late-fall activity.

“After a long dormancy in the Southern states, black flies re-emerged here in 2009,” Goddard said. “Nobody knows why they came back, but they come out in huge swarms and feed on blood by biting animals, people and birds.”

The two main species of buffalo gnats that are common in Mississippi are the turkey gnat and the Jennings gnat. The turkey gnat is known for biting and leaving bumps, swelling and itching, while Jennings gnats are known for persistently flying around faces and eyes.

“Turkey gnats kill birds by swarming them and clogging their esophagus,” Goddard said. “They suffocate birds through their mouths and throats.”

Anyone being pestered and bitten by buffalo gnats can find fast relief by going indoors, as these gnats are reluctant to enter enclosures.

“Put a fan blowing across you or your animals, and get your chickens inside a coop to protect them,” Goddard said. “These gnats don’t fly very well if there’s a lot of wind, and they are only active during the day.”

Martha Pulido Landinez, associate clinical professor at the MSU College of Veterinary Medicine’s Poultry Research and Diagnostic Laboratory in Pearl, said the cases the lab received in 2021 arrived in May, but not all backyard bird owners bring the affected birds to the lab.

“The real impact of this problem each year can be difficult to establish,” she said. “I am writing about the cases we got last year, and I am mentioning the increase in new owners of backyard chickens factoring into this problem.”

In addition to Goddard’s recommendations, Pulido-Landinez suggests screen wire enclosures to block flies.

“Placing one mesh screen over the coop’s windows and vents may prevent these flies from coming inside the coop,” she said. “Check your birds constantly, looking for gnat bites on wattles and combs. These bites can produce discomfort in your chickens and constant scratching at the head or face.”

Pesticides, many of which contain the active ingredient permethrin, are available to kill and repel adult gnats.

“There are on-animal products labeled for mosquito and biting fly control that you can apply directly to chickens,” Pulido-Landinez said. “Many of these products contain the active ingredient permethrin. Another product has the active ingredients tetrachlorvinphos and dichlorvos and may also can be used directly on poultry.

“Remember to read and follow all label directions for exact amounts and dilutions for these and any other insecticides, especially when using on-animal products,” she said. “The use of pesticides is only a temporary treatment and will need to be reapplied.”

More information on buffalo gnat control is available in MSU Extension Publication 3755, “What to Do About Black Flies (Buffalo Gnats)” at http://extension.msstate.edu/publications/what-do-about-black-flies-buffalo-gnats.