he only larvicide that kills all 4 larval stages of mosquitoes. Prevents mosquitoes that may transmit West Nile, Zika, and Dengue viruses and heartworms to dogs and cats. Patented bi-layer tablet with fizzing action and a slow-release layer that dissolves over time to give 60 day control. Can be used in areas that contain fish and plants. Covers the top and bottom of water to kill no matter where mosquito larvae are hiding.