Bug bites :-(

My horse's previous owner warned me that she is very sensitive to bug bites, so before the weather started warming up, I invested in a nice fly mask (with ears) and fly spray for her. The mask is obviously doing its job, but I'm not so sure the fly spray is. It's "Bronco" fly spray, and it's water-based.

She came in the other day from the pasture with these tiny bumps all over one side of her, in the area that would be under the back of the saddle pad on the side and just behind the saddle pad (English saddle pad), again only on the side of her. If you move the fur and look really close at them they're not red or anything, just skin-colored bumps. They don't seem to bother her, but I'm wondering whether they're bug bites or hives? Some at the barn who have looked at them say "oh those are hives" and others say "those are reactions to bug bites" from the little gnats that are out already here in Ohio (and some flies are starting to come out too). So a couple questions for the forum:

1. Do these sound like bug bites or hives?
2. If bug bites, what is a better fly spray I could use to keep them off her? Should I get a fly sheet instead?
3. If hives, what could be causing them and should I be worried?!

Thanks!

If they're all over her body, hives. If it gnats, they attack the belly area first where there's no hair. She's probably allergic to something in the spray. I use Absorbine and haven't had any problems. Also, you might want to consider a feed through bug control such at Bugzo or Bug Check. I don't really find that fly sheets do much. The bugs can still climb under there and drive the horses nuts.

Thanks for the tip about fly sheets -- I kinda wondered that myself. I would think the same thing as you said above about reacting to the fly spray, except the bumps were there before I ever used it on her (or any fly spray for that matter) -- they're restricted to one area which is strange and why I'm asking for others' opinions. If you look at the photo below, they are on her other side (far side) but just to give you an idea of the location, they would be right under the saddle pad where it has her name "Sandie" embroidered and around that general area.

Is she in a grass pasture? Maybe she rolled on something and has a contact allergy? Did you recently wash the pad, or the horse? Bugs don't usually pick that area. I'm not sure what that is! I guess if it doesn't bother her, no harm no foul.

You could call it a grass pasture, although there isn't much grass in it unfortunately! The place where I board has 3 small pastures and 40 horses so it's pretty picked over - so they spread hay everywhere for the horses. But there is some grass.

And I DID just send the pad out to be washed for the very first time come to think of it!! I can't remember if those bumps showed up before or after the pad was washed, but that's certainly an option. The spot that it's in does seem strange, especially it being on only one side of her body. And they don't seem to itch or anything, she's not rolling around or looking at them and if you touch them she doesn't even pay you any attention. If they were hives, what would the symptoms be?