The females slice open skin and wait for blood to pool. Then, they lap it up. That's not quite like a mosquito, which taps into a capillary and draws up blood with something akin to a hypodermic needle. And, unlike mosquitoes, biting gnats lack the anesthetic component of the bite that helps them go unnoticed. But if one gets you, expect to itch.
More sensitive people get welts and lesions that can irritate for several days.
The blood-suckers are attracted to the carbon dioxide we exhale and the heat lost from our heads. That's why they often bite their victims on the scalp and face. They also are drawn to chemicals in sweat, Williams says. And, sadly, biting gnats like the weather most of us do - temps in the 70s and cool nights. That means gnat season could stick around until May and return again in October and November when the heat gives way to cooler days.