A man took to Facebook to share his results of a DIY Backyard Horsefly trap for pools and many others cited the trap for saving their summer swimming from pesky horse and deer flies.
The trap is made from a black beach ball (either bought or spray painted) that is sprayed with tanglefoot.
The science of the trap is simple; the flies are attracted to the heat of the ball and will land on it only to get stuck in the tanglefoot. Several commenters on the above post swear by the results; significantly less horse and deer flies buzzing around their head when swimming.
The key is to keep it close to the pool, as one commenter noted. Even 10ft away and the ball won’t have the same result of helping to keep your swim fly-free.