Pearl has trouble with the corn flies and harvest mites - I get both in copious quantities where I live and there's absolutely nothing I can do. Corn flies just about gone now, but the harvest mites have been around for a month and will last until October...
Fortunately the monthly Frontline is keeping the problem more or less at bay, but doesn't completely keep the beasties in check. So a daily swab of affected areas with surgical spirit is pretty well much a must.
Pearl gets them between her toes, on her belly and on her tail.