We're thinking of spraying the yard (city lot) with a pyrethrin-based over-the-counter spray for chiggers, mosquitos and flies. The kind you hook to your hose and have to do every few weeks. We've done all the low-bore things to eliminate these pests. My question is, if we put the few hens we have in the garage while we do this and confine them there for a couple of hours after, will it be safe to let them free range the yard as usual afterward? Anyone know? thanks.