Nematodes are simple roundworms.
Colorless, unsegmented and lacking appendages, nematodes may be free-living, predaceous or parasitic. Entomopathogenic nematodes are lethal to many important soil insect pests that attack nursery plants, yet are safe for plants and animals. This high degree of safety means that unlike chemicals, nematode applications do not require safety equipment. There are no re-entry times, no problems with residues, and groundwater contamination is not an issue. Most biologicals require days or weeks to kill, yet nematodes, working with their symbiotic bacteria, kill insects in 24 - 48 hours.