We have had a serious flea infestation for the last month or so. I have used everything on my dog and cat- frontline, advantage, flea bath, diotomateous earth, flea bombs, house sprays, etc. I still have the darn things! My poor dog is bringing them in from her adventures out and about the farm. Can we spray the lawn with flea spray or will that harm the free ranging chickens? Any other ideas are welcome, as I am ready to scream.