I used to have the habits of freezing my hay before feeding them to my animals. But I've been stop doing that for awhile. For no reason in particular did I stop doing it. Maybe I just forgotten about it. Anyway, as a Chinese saying 'when you visit the mountain often you'll one day meet a tiger'. 2 of my 1 month old Teddy Guinea Pigs and a nursing chinchilla mom have been the victim of mites. Of cause me as well. Those hitch hiking mites! Always put your hay in the freeze before use! Must not forget about it. Hate being bitten by things that I can't see.