or called Aquatic midges. Don't know if that is what you have but if they are around your house and hanging onto the lanai screen/windows then it probably is the blind mosquito. When they get inside they do look just like a gnat because they are so small. They don't bite thank goodness but are a nuisance. It use to be a concern for people living close to the ponds etc but it seems like there are so many of them now that once hatched they go where the wind takes them. They also attach themselves to the house around the eaves. Their life span is only a couple of weeks and the way they breed is very difficult to eliminate them. I use to see them in March for a few months then again in September but I have them now from March thru December. Massey said they can spray but it is only for the moment because of their cycle. There is a brief article written in 2011 below about the ones in Mount Dora. Doesn't sound like I have them that bad but I can not go out my lanai because there are so many on the screen. Kinda creepy...
Blind mosquitoes: Blind mosquitoes are swarming — and the season goes until November - Orlando Sentinel