One of the most disconcerting sights to a gardener’s eyes is a plant chewed to pieces by insects. It’s not surprising, then, if our first reaction upon seeing a bug in our garden is concern. But if your second reaction is to kill that tiny critter, stop. Many insects perform functions in the garden that are beneficial to humans. One of these is preying on other insects, something known as “biological pest control.” Beneficial insects are increasingly recommended as an alternative to potentially toxic pesticides, but the world of insects can be a confusing one. Click here to view images of some common beneficial insects.
Insect predators actively hunt in immature stages, moving about to consume prey. The adults may, or may not, continue as predators. Examples commonly found in gardens include lady beetles, ground beetles, green and brown lacewings, flower flies, minute pirate bugs, predatory stink bugs, assassin bugs, damsel bugs, mantids, predatory mites, and spiders.
Once an insect reaches an adult stage, it possesses the capability to use parasites for hunting. It locates a proper host, and lays an egg in or on the host insect. The developing parasite slowly consumes and ultimately kills the host. Braconid wasps, ichneumon wasps, encyrtid wasps, Trichogramma wasps, and tachinid flies are common parasites of garden pests.
Hunting wasps actively hunt for insect prey to feed their young. Some hunting wasps, such as paper wasps and hornets, are social insects that produce a colony. Others nest individually in small holes they locate or excavate. The most common of these solitary wasps are the sphecid wasps.