Commercial suppliers of beneficial nematodes suggest their use on white grubs, cutworms, armyworms, fungus gnats, carrot weevils, borers, cabbage maggots, and wireworms. To obtain best results with commercially supplied beneficial nematodes, the supplier's instructions must be followed carefully. Typically, nematodes can be stored in the refrigerator for a short time after arrival because they are in a dormant state. After dormancy is broken, they must be used immediately. They prefer a moist soil and are damaged by light and so should be applied in the evening.
Beneficial nematodes move faster in sandy soil than clay.
Other important general considerations in purchasing beneficials are finding a good supplier and dispensing the insects in the field. Currently there are no certification or quality assurance standards for insect-rearing and few protections for the customer if insects fail to establish. Thus when a release for biological control fails, it is hard to know where to place the blame. Insects supplied may have been the wrong type, they may have died in transit, or while the grower was holding them before release or they may have been poorly placed in the field so that there are too many in some areas and none in others. Even distribution in the field is often difficult.