Hippodamia glacialis , a predator of aphids. Aphid killed by fungus. J.Ogrodnick Predators, such as lady beetles and lacewings, are mainly free-living species that consume a large number of prey during their lifetime. Parasitoids are species whose immature stage develops on or within a single insect host, ultimately killing the host. Many species of wasps and some flies are parasitoids.
Pathogens are disease-causing organisms including bacteria, fungi, and viruses.
They kill or debilitate their host and are relatively specific to certain insect groups. Each of these natural enemy groups is discussed in much greater detail in following sections. The behaviors and life cycles of natural enemies can be relatively simple or extraordinarily complex, and not all natural enemies of insects are beneficial to crop production. For example, hyperparasitoids are parasitoids of other parasitoids. This guide concentrates on those species for which the benefits of their presence outweigh any disadvantages.