They're smart enough to stay off it when it's a bright, humid 90 degrees outside. I'm not.
The horses were inside, hiding from giant, evil horse flies (see blog about them here), but got concerned about the footsteps overhead, and came out. I took a picture of Fritz and Remi from the edge of the roof. The hand-size swelling on Remi's side behind his shoulder is from a fly bite. He has several on his flanks, large lumps with a scab at the center. Just like with mosquitos and people, there's always some poor guy who gets twice as many bites as everyone else. That's Remi.