Biological Control: Putting Beneficial Insects to Work

By Pat Dickey, Fairfax Master Gardener
There are many ways to eliminate pests in our flower beds and vegetable patches, but biological control is a method organic gardeners advocate. Simply put, biological control suppresses or prevents a pest outbreak by manipulating the pest’s natural enemies. Biological control does not completely get rid of the problem. Natural enemies require their prey or hosts for survival, so a small population of the pest is always needed. Biological control does, however, keep the nuisance at tolerable levels–without the negative effects of chemical pesticides on our health and environment.

Lady beetle

Hippodamia convergens. Common American lady beetle often sold to gardeners for insect control

The three Ps of biological control

Natural enemies of pests are also known as beneficials. There are three types of beneficials in insect pest control: predators, parasitoids, and pathogens.

Predators
Beneficial insects that actively consume many other insect pests during their lives are predators. Some predators feed only on one or a few species of insects, but most are generalists and feed on a variety of insect prey, and even each other. The most common insect predators are lady beetles, ground and soldier beetles, praying mantids, assassin bugs, predatory stink bugs, and the larvae of lacewings and flower flies.