We have in IL now what are called buffalo or vampire gnats. Good Lord they are nasty, biting little sons of guns. The best deterrent is vanilla scented spray, a product called Buggins or WD-40 seems to work as well. We never had them until about 8-10 years ago and they are THICK and miserable. Lots of people lose poultry and it is hurting our wild turkey, quail and bald eagles (I'm sure other birds as well but those are the most watched here). They swam the birds heads, get in the nasal passages and suffocate them, the young are very vulnerable. I've heard they were introduced to our area to combat the asian beetles. If thats true whoever thought of it needs horsewhipped. If not true, I don't know how they got here but they are invasive to our part of the country.