The best defense against Mother Nature is Mother Nature. Meet STEM Kills Flies, Mosquitoes and Gnats – a bug spray for home and outdoor use made with botanical extracts that are safe for you, but deadly for bugs. STEM's scientists decode the power of nature, scientifically optimizing it into effective bug-fighting forms.STEM plant-based active ingredient bug spray is formulated with botanical extracts to kill flies, mosquitoes and gnats. Our insecticide is safe for use around people and pets (when used as directed) and was tested by entomologists. It has no added dye, fragrance, or harsh chemical odors and is made for indoor and outdoor use.STEM helps protect your family. Rooted in Nature, Optimized by Science.