You have to know the insect problem you have before applying the right biocontrol. Heterorhabditis is a beneficial nematode that spreads a bacterium that kills many root-feeding insects. This nematode is a bacterial-feeder, not a predatory nematode. But it is eaten by the insects, or contacts the surface of the insect larva, thus inoculating the insect with the bacterium that destroys the insect. The nematode then hangs around to eat the bacteria that killed the insect, because the bacteria grow to enormous numbers on the dead insect.
Baby nematodes then go off to find another insect, and start the cycle again.
The take-home message from this section is to sample to assess the foodweb in the area that will give the information about the disease, pest or problem you want to remove.