Aphytis wasps are attracted to aphids. If aphids are not present in the garden when the wasps are released, the wasps will fly for some distance seeking aphids to parasitize. Trichogramma egg parasites can be purchased to supplement those which occur naturally in North Carolina. Trichogramma wasps are almost microscopic, but they can fly about, seeking caterpillar eggs in which to lay their own. If no caterpillar eggs exist in the landscape, the wasps will seek them out elsewhere.
Parasitic nematodes are available from several sources.
They control white grubs and other subterranean insects. Even insects such as cutworms and armyworms are susceptible to parasitic nematodes. Because parasitic nematodes are difficult to rear and because the facilities that produce them are limited, the use of parasitic nematodes can be relatively expensive. The cost of nematodes is likely to decrease as use increases and production facilities become more efficient.