It seems that all of the "safe" fire ant remedies do not kill, but cause them to relocate, ie boiling water, grits, orange oil, citronella, cooking oil. The ones that kill are probably not safe as the chickens would eat whatever it is (I could see mine gobbling up the Amdro). I did see my chickens eating fire ants yesterday, so I may be stuck with relocating the fire ants to outside the fenced yard, then trying the usual chemicals to kill them. I usually try to at least run them into my neighbors' yards anyway, if I don't kill them.
