Hey Gram (that's what I called my grandmother),
foals shouldn't have any fly spray on them--but if they're inside they're fine. I did use a roll on and ran it around their eyes and down their backs. I also put fly traps around the pasture and pick the pastures daily. That seems to help. Now that my foals are a year old--everyone here will have a fly mask with ears!
I wanted my foals running in the pasture as soon as possible for the mama's and foal's mental and physical health, so the day after they were born, I'd have them on a small pasture for just a few hours. I'd carry the foal out so mama wouldn't get upset. Then they'd go out longer each day. The mama needs to be alone in the pasture for the fist days--the foal goes running off and she goes nuts trying to keep up. She couldn't deal with more horses in there too. After three days I let the first mare who foaled in with her buddy--another mare. They always respected each other's space. But the foal was 4-5 months old before being introduced to the rest.
I miss parts of this whole event--but I told Tracy I can see it's much wiser to skip the breeding/foaling out nonsense and just buy someone else's foal. Then I can pick colors! :lol: I am so grateful for experiencing it six times--a miracle for sure.