10 Million Live Beneficial Nematodes Sf - Fungus Gnat/Rootknot Gall Exterminator Beneficial Nematodes are a natural and effective way to control soil pest without using harsh chemicals. Beneficial Nematodes are microscopic round worms that attack over 200 different species of soil pests. Easy to apply and Harmless to humans and pets. Our Live Beneficial Nematodes are Guaranteed Fresh and Alive! Treats up to 600 Sq. Ft. Depending on Infestation.