It might be of some benefit if not diluted. Tea tree oil can be used if rubbed into roosts/ sprayed into cracks, etc. (kills ectoparasites as quickly as eprinex preps ~1hr. in a petri dish - Sevin takes up to 24hr), however, use of tea tree oil, even diluted, directly on poultry can result in a toxic reaction and kill them. We mixed a witches brew of Eprinex Cattle Pour-on/Tea tree oil/Adams tick and flea spray to clean out neighbor's coop a few years back (place was, and chooks were, crawling with Northern Fowl Mites). Stripped coop down to wood, burnt all removed bedding, etc. Treated chooks with eprinex pour-on .5cc on upper backs, placed them on temp. bedding in dog run (both sevin/DE mixed into straw and wood chips). They returned chooks to coop the following day. Haven't been reinfested, yet (couple of years, now). Had to strip and bag up our clothes in garage after we'd walked back to our place - NFM's like to scurry towards one's head. Just bagged up and dosed clothes with a bit of eprinex and, later that day, dumped `em into washer. Tea Tree Oil shampoo for `bod' decontamination and that was that. Probably got enough eprinex through the skin to kill any stealth worms in our guts, as well (if one thinks they might be sensitive wear gloves - like wearing a N95 rated mask when using Sevin/DE).
Stripping the coop for thorough cleaning, and limiting exposure to wild birds will go a long way to preventing reinfestation (carry chooks around a bit every week - roo's in particular as they tend to be infested first - NFM's prefer feathers near roo's fundament, not the hen fluff - if the NFM's have taken up resisidence you'll feel a few stragglers migrating up your body towards your head (won't dine on you - just cause `emotional irritation'
).
Some links with info:
Aviagen puts out a series of tech documents on diseases/parasites with good photos:
http://www.healthybirds.umd.edu/Disease/Deworming%20Birds.pdf
INCHEM is a good source of detailed info on all things chemical (a lot of info on Ivermectin as it is widely used in humans):
http://www.inchem.org/documents/pims/pharm/ivermect.htm
Our vet also suggested eprinex for topical use for chook `bugs' (why we had it handy when neighbor called).