This formula helps naturally repel fleas and mosquitos primarily because of the lemongrass and citronella. (geekwrapped.com)
Adding a clove of ground garlic or spoonful of brewer's yeast (teaspoon for small dogs and tablespoon for large dogs) can also help repel fleas. (vetinfo.com)
It also repels fleas with natural peppermint, clove, cedar, and rosemary oils. (1800petmeds.com)