Last week some of you gave me advice about diatomaceous earth to treat fleas inside on carpets. Can this be used outside on lawns and barns? A friend who cares for other people's pets/livestock has clients on a cruise for 5 weeks (already gone 2 wks) and called them about their house, lawn & barn being infested w/fleas. They said to do "whatever" and in talking w/her I told her about the stuff you advised. She wants to know if it can be used outside too. Anyone know? She's being eaten alive while she's there, not to mention their horses, cows, newfs and Irish wolfhounds they breed.