Kyle Winkelmann has learned in the past two weeks that if he's going to get into the cab of his tractor, he had better do it in a hurry.

"I run really fast and get in quick, or else they'll get in with you," said Winkelmann, who farms near Tallula, about 15 miles northwest of Springfield.

"They" are buffalo gnats, a type of black fly that has hatched in unusually high numbers the past two weeks in west-central Illinois.

The females bite. They're parasites, spending most of their roughly three-week life looking for blood to provide the protein needed to lay eggs. Their saliva causes an allergic reaction, leaving big, red, itchy welts on people and animals.

In the 10 or 12 days since the little bugs — about the size of the exposed lead at the end of a pencil — hatched, they've irritated farmers like Winkelmann and driven golfers and gardeners indoors in scattered spots between Springfield and the Mississippi River. They apparently have also killed some poultry.

The state Department of Agriculture received reports from several people who lost birds from backyard flocks and tested the poultry for bird flu and other ailments, spokesman Jeff Squibb said.

"There is no test per se for buffalo gnats in a necropsy," he said. "It's a process of elimination, and all other causes have been eliminated."

The birds could have died of blood loss, allergic reactions to the bugs' saliva or even asphyxiation, with their airways clogged with gnats, said Colleen O'Keefe, manager of the department's food safety and animal protection division.

Illinois doesn't have much of a poultry industry, and its few big farmers raise their chickens indoors, safe from the gnats.

The state's outdoor flocks tend to be like the one Betty Dunker keeps in her yard near Hull, about 12 miles southwest of Quincy along the Mississippi River. Dunker, 76, has a mix of chickens, peacocks, doves and other birds she says she keeps for her grandchildren.

About 30 of the birds died during the past 10 days after being tormented by gnats.

"My chickens were so tired from fighting these gnats that they could hardly even walk," she said.

Buffalo gnats drive fishermen and other outdoorsmen nuts a few weeks a year in Minnesota, upstate New York and many places in Canada.

They're not uncommon in Illinois. Linn Haramis, an entomologist with the state Department of Health, recalls a heavy hatch a few years ago along the Fox River not far from Chicago.

University of Illinois entomologist Phil Nixon suspects cleaner water than the region's streams have had in decades may be the cause of the increase.

The gnats lay eggs on sticks, rocks and debris near or in running water, he said, and the larvae use a fan-shaped set of bristles to capture whatever floats by.

"They essentially eat whatever gets caught in that fan," Nixon said. "If what gets caught is pollutants, they're poisoned."

If the water is clean, he theorizes, their populations will be healthier.

Nixon said the current hatch of buffalo gnats should be gone in the next week or two, and only one generation is born a year.

In the meantime, Squibb and others said livestock and poultry owners can protect their animals by keeping them indoors during the day, when the gnats feed. People also should stay indoors, or at least limit their outdoor time. Insect repellants seem to have only limited effect, according to those who've tried them.

Winkelmann is one of them. And since he works outside, he's resigned to being bitten.

"They can bite you on the inside on the nose and everything," he said. "There's no escape from it, nothing you can do."