Once the bacteria are introduced into the insect host, death of the host usually occurs in 24 to 48 hours. As the bacteria enzymatically breaks down the internal structure of the insect, the Steinernematids develop into adult males and females which mate within the insect's body cavity. Heterorhabditids produce young through hermaphroditic females. As the nematodes grow, they feed on the insect tissue that has been broken down by the bacteria. Once their development has reached the third juvenile stage, the nematodes exit the remains of the insect body.
Parasitic nematodes are beneficial for six reasons.
First, they have such a wide host range that they can be used successfully on numerous insect pests. The nematodes' nonspecific development, which does not rely on specific host nutrients, allows them to infect a large number of insect species. Second, nematodes kill their insect hosts within 48 hours. As mentioned earlier, this is due to enzymes produced by the Xenorhabdus bacteria. Third, nematodes can be grown on artificial media.