There’s been an invasion in the northern Illinois region, but none of us can see it happening.

According to the Illinois Department of Public Health, a microscopic species of oak leaf gall itch mites may have made their home in the oak trees and on the skin of some unlucky folks in the area.

They feed on midge fly larvae, which are contained in the brown, crusty bumps on oak leaves. It turns out that these invisible pests are actually the perfect predator.

They are small, which allows them to float on the wind and pass through screen doors and loosely-woven clothing during what the Department of Health calls “mite showers.”

Although the mites bite, area residents are not in danger, since the bites are not poisonous and produce only an itchy lesion.

“The best counter to the itchiness is to treat the area with cortisone cream or itch cream,” said Peg Carroll, coordinator of the Communicable Disease Program at the DeKalb County Health Department.

The greatest danger from the bites is the risk of infection from excessive scratching of the lesions, which usually appear on the neck, face, arms and upper body.

“They’re around,” said Bob Drake, head of the Environmental Control Department at the DeKalb County Health Department. “The rash clears itself up. It’s been harmless so far.”

The bites do not hurt and take about 12 hours to produce a visible lesion, which is usually present for up to two weeks. There is no way to tell when the itch mites have made themselves at home on your face, considering they are less than 1/125 of an inch with a miniscule 1/700 of an inch mouth.

“There haven’t been a whole lot of cases in the area so far,” Drake said. “But there were a few times when we didn’t know exactly what it was when we saw it. But if you walk anywhere outside, you run the risk of itch mites.”

After being outdoors, especially in the area of large trees, the Illinois Department of Public Health recommends a hot shower, along with soap to get rid of any hitch-hiking mites. Another precaution is to wash any clothes that were worn outside before wearing them again.

“They’re a nuisance,” Carroll said. “We’ve had some incidents, but nothing too big, maybe a few calls from walk-in clinics reporting strange rashes.”

In 2004, areas of Kansas, Missouri, Nebraska and Texas experienced similar outbreaks, which were deemed to be caused by the oak leaf gall itch mite. There is no way to kill them with pesticides, since they only feed on the outside of oak leaves and repellent with DEET proves no real deterrent to the buggers, since they only bite those they accidentally fall onto.

“They’ll be hanging around here until the first hard frost kills them off,” Carroll said.