The neem works as an insect repellent. I bought some to keep bugs from stinging my pumpkins and it really worked. We sprayed it once and had one or 2 stings as apposed to the 100's we normally got. Dilute some dishwash soap and spray that on your aphids.
Well, Sevin, as I said is great. And bathing them I hear, helps a lot too. You know you can always wait until they go sleep and just pick them off the roosts
We used to buy this type of mite/flea dust in SA that we'd pour in a plastic bag, then we put the chicken, one by one, in the bag and shook it. Ended up with a flock of snow white, slightly ticked off chickens, but it took care of the bugs!