Gnatrol is a Biological Larvicide that, when applied to your reservoir kills gnats quickly and effectively. A strain of Bacillus thuringiensis v. israelensis (BT's) that specifically controls the larva of fungus gnats and helps break the reproductive cycle to get rid of them! BT's are a biological pesticide that contain naturally occurring bacteria in different strains that target specific insects. Non-toxic to animals, birds, humans, fish or beneficial insects, they do not persist in or contaminate the environment in any way. For use as a foliar spray, in the growing medium or as a soil drench. For Hydro applications, simply add to the nutrient solution, run until all signs of gnats are gone and resume with your regular feeding schedule. **Also kills Thrips in the early part of their life cycle. Available in Pints, Quarts, and Gallons.