Almost none of the insects that you'll come across in the garden are harmful to you or your plants. Some insects feed primarily on wild plants and leaveyour garden plants alone. Other insects species directly benefit the garden. Wild and domestic bees, for example, perform vital functions like pollination. And some species survive by preying (feeding) on or parasitizing (living within) other insects. The species that attack other insects are especially significant to the gardener, since they're one of the tools you can rely on for pest control.
Predators eat other organism. Most insect predators, like ground beetles or rove beetles,aren't fussy eaters. They're called generalists, and they'll eat pest insects as well as fellow predators that are small enough to catch. Other predaceous insects are prey-specific. For example, some lady beetle species prefer spider mites, some consume only mealybugs,and others restrict their diet to aphids. Notall predators are insects. Insect predators like spiders, centipedes, and several species of mites are also important pest controllers.
Parasites are among the most important biological pest controls.They live on or in other organisms. Parasites steal nutrients from their host but they usually don't kill it. Parasitoids are a special kind of parasite. They make ideal biological pest controllers because they kill their host. Most parasitoids are tiny, aggressive wasps or bees that lay their eggs within the living host. Parasitoid larvae hatch and consume their host,
then form a cocoon before emerging as adults that are eager to find more pests. Most parasitoids are species and host specific. One kind may attack only a pest's larval stage, for example, while another kind will parasitize the adult form of the same pest.