Beneficial Nematodes hunt down, penetrate, and kill most soil dwelling pests. They will remain effective for about 2 years, but annual applications are recommended. They will also attack over wintering adult insects, pupae, diapausing larvae, and grubs when they are in the soil, bark, or even ground litter. They do not affect humans, animals, or plants. They are completely compatible with beneficial insects such as ladybugs, lacewings, and praying mantids and do not harm earthworms.