Both Steinernematid and Heterorhabditid nematodes are considered as excellent biocontrol agents against soil dwelling insect pests of many economically important crops. This is because they have a broad host range, the ability to search actively for hosts, the ability to kill their hosts rapidly within 24-48 hours, the potential to recycle in the soil environment, no deleterious effects on humans, other vertebrate animals, non-target organisms and plants and no negative effects on environment. In addition these insect parasitic nematodes can be easily mass produced using both in vivo and in vitro methods and applied using traditional insecticide spraying equipments. Since these nematodes are compatible with many chemical insecticides and biopesticides, they are easily included in IPM programs. Entomopatogenic nematodes also been been exempted from registration and regulation requirement by US Environmental Protection Agency (EPA) and similar agencies in many other countries.