Cover and shake the mixture, then observe. However, some nematodes attack and kill insects. These nematodes do not directly kill the insect. Once inside the host insect, the bacterium becomes active. The nematode feeds on this bacterium, and the waste by-products of the bacterium become lethal to the insect, killing it by bacterial septicemia.
Nematodes require an aqueous environment or they become inactive.
Many nematode products are labeled for soil inhabiting pests such as beetle grubs and black vine weevil larvae. However, obtaining and maintaining the correct amount of soil moisture for several days is difficult and the desired level of management may not always be achieved. These nematodes require a moisture film around the soil particles in order to stay active and to be mobile. But if the soil is too wet, they cannot achieve traction on the soil particles and they will float helplessly in the saturated soil. If it is to dry they will become dormant.