What can we use to keep the lice population under control in our sick hen's pen? We have de-loused HER with Ivermectin, but I'm reluctant to use commercial pesticide to spray her living quarters with, I'm afraid it might be too much insecticide for her. Or would it? The Ivermectin won't work if she keeps getting re-infested from her pen. Is there something organic we can use that might help?