Ear biting Gnats

I have 3 horses and a mini at home. Apparently my pastures are infested with gnats. I have seen clouds of them if the sun hits them just right. I am in the Deep South, hot and humid. Fly Spray works fine for the few flies I have (except B-52 Bomber Season), but nothing for gnats. I put Swat on ears, fly masks with ears, but they scrub their manes and ears on trees anyway. The land is flat and dry, open fields with Pecan trees. There is one pond on the neighboring property. I don’t have a problem with mosquitos. It’s too hot to keep them in during the day. I have one run-in shed with a fan in a paddock for the one worst afflicted, also heavey horse. What else can I do?

Gnats like tall grass. Do you have any tall grass that you can mow down?

There is a natural spray brand, Buggins, that makes a gnat spray, and it actually works really well on people. I might look over the ingredients to make sure it’s okay for a horse, but I’d try that.