Since 2012, we have seen annual outbreaks of biting gnats each Spring throughout Central Texas. Unfortunately, there is no known method of control. Biting gnats emerge in large numbers and rarely land on foliage, so foliar treatments targeting mosquitoes are not effective against biting gnats for more than a day or two.
Their bites are not particularly painful, but the skin reaction to the bite is much more severe than that caused by mosquitoes. There is a lot of swelling around the bite area that remains for 3 to 5 days. They seem to bite most often around the face and ears. I actually was bitten on the cheek while in the Indian Lakes neighborhood 2 days ago and it is still a little swollen.
Usually, they start to go away by May or June. The only defense available is insect repellent. I recommend using a repellent that has picaridin as the active ingredient. It’s not as harsh as DEET, but just as effective. I’ve observed that dragonflies are aggressive predators of biting gnats, but don’t seem to be able to eat enough to alleviate the problem.
It’s not clear whether these are buffalo gnats (a.k.a. black flies) or biting midges. Both cause similar skin reactions and hard to control. Buffalo gnats breed only in flowing water, while biting midges breed in muck around water edges. Since the problem began following the drought of 2011, when there would have been a lot of muck from receding water levels, I suspect they are biting midges. Texas A&M Entomologist, Bart Drees (retired), wrote an article identifying the problem insects as buffalo gnats. However, he noted that their appearance and abundance away from their expected breeding habitat was unexpected. Despite being a recent victim of these little monsters, I’ve yet to collect one for identification.