- Nantucket Spider for Dogs is specially formulated to repel mosquitos, biting flies, ticks and fleas. Our repellent does not contain "citrusy" oils that dogs dislike, instead it contains thyme oil to repel fleas and a blend of other effective essential oils, including rosemary, peppermint, cedarwood, and geranium. After an initial pungent scent (that's the thyme oil), Nantucket Spider for dogs quickly mellows into an earthy, pleasant, cedar scent that will not annoy your dog. With Nantucket Spider for Dogs, your best friend's life will get a whole lot less itchy!