CUSTOMER RECOMENDATION. A recent guest at Countryside Gardens saw our display of mosquito products and raved about this patch. She tried another patch but said this one “IS THE BEST”. The Mosquito Patch has the highest active ingredient, vitamin B1, of any patch available on the market today. Another advantage is most patches are colored. This one is clear and blends in with any skin tone. A safe and natural way to repel mosquitoes, flies and gnats, the patch contains no harsh chemicals, pesticides or insecticides; only the vitamin Thiamin B1! Research has shown that large doses of Thiamin B1 produces an odor that is not detectable by humans, but is disagreeable to mosquitoes. This is the perfect alternative to chemical sprays for those hypersensitive/allergic individuals.