If ivomec doesn't work on these things, what about Frontline? You can apply it the same as cattle pour-on. Use a small syringe/needle to suck it out of the dropper package, and then dispense pea sized drops onto the chickens' skin by parting the feathers. It's off-label of course, but so is most of the other stuff people are naming. I'd use Frontline before I used Adams flea spray, it's just a safer type of drug. txcarl1258 do you know if it works on them?