natural "Spot ons"

does anyone have any experience with the natural spot on products? I was wondering if they worked and if I could create my own using citronella, eucalyptus etc... in a carrier oil. I probably would spray it on not really use it as a spot on to prevent irritation. I always find a few lice on some goats in the winter and I'm trying to put together a plan that doesn't involve pesticides or wormers (ivermectin will kill biting lice but....)

Last fall I bought some of the natural spot on they sell for cats with fleas. I used it on my newest cat, Trixy. I really do feel like it repelled fleas. Dunno what it would do for goats, but I'm pretty sure they sell a similar product for dogs.

Well if I see any nasty lice appear this winter I will at least give it a shot. or better yet I will start spraying them a bit each week as they start growing in their winter coats.