It's a fact of summer life -- little donkey legs get ferociously bitten by flies in the warm weather. Last summer we tried all manner of prevention. Naturally we started with traditional fly spray and when that didn't work moved to smearing legs with vaseline. That just ended up oozing in the heat. Hmmm, what to try next. Aha! Vet wraps, which for the non-horsey folks are self-sticking bandage like strips. Well, those didn't stay on, even with duct tape.
At the end of last summer, poking around on horse supply sites, I found pony leg wraps. Bought 12 and we just started trying them out about a week ago.