Has anybody tried teatree oil as a natural repellent I know it helps repel head lice
The concept of using essential oils as a natural insecticide is an appealing thought. (See footnote below).
However, tea tree oil is a known toxin to cats (cumulative effect even in small doses/exposure) and to dogs (higher concentrations). It was also listed as a household toxin for parrots in a poison control parrot site.
As to poultry, I see a lot of colloquial remedies mentioning it for lice and mites in chickens, especially on "natural" pages, but I've not seen much study or articles as regards to safety....nor any indication for concentration or use. (EDITED TO ADD: see below footnote).
Most essential oils are listed as toxic to birds and small pets (numerous sites)
There is a good European study that shows Tea Tree oil in undiluted concentration (100% concentration) is toxic to rabbits and generally an irritant to many species. However it did better in lighter concentrations (1% to at most 25%). In another study chicks were used to test the toxicity of tea tree oil. The chicks did show neural toxin response to all 3 types of tea tree species under experimental conditions.
So until I see something that shows it is safe for direct application on chickens, or the fumes are safe for bird inhalation, I would not rush to use it, not even diluted, as it is of questionable efficacy.
FOOTNOTE:
The study linked below does about the best job of efficacy of essential oils for ectoparasites in veterinary use that I have found.
While the area of essential oils is an exciting avenue for the industry to explore, in search of better means for parasite control in order to avoid the resistance and toxicity problems associated with synthetic insecticides, it is not without its own set of problems.
The article below concludes that: 1) essential oils are generally too volatile, evaporating too quickly to provide any lasting effect especially for parasites that transform (egg, larvae, adult); and 2) oil concentrations varied greatly from one batch to the next in products...quality control and standardization is an issue...making consistent application problematic.
Further, the study found essential oils could be very problematic for poultry. In particular pennyroyal and thyme were toxic for wide spraying of poultry houses...several chickens died and weight and egg production were reduced.
http://onlinelibrary.wiley.com/doi/10.1111/mve.12033/full
@casportpony what is your experience with essential oils for poultry?
LofMc