Biological Pest Control Methods

Provide food by growing plants that attract beneficial insects. These often have small flowers that attract both natural enemies and pollinators. Good plant choices include goldenrod, garden herbs, and broccoli family plants (brasiccas).

Provide habitat for predatory insects, such as spiders and ground beetles. Leave untended areas with standing foliage. Use loose straw or wood chip mulches.

Grow native and non-native plants. Native plants attract the widest variety of beneficial insects. The native plant yarrow (Achillea millefolium) hosts a variety of insects as shown in the photo.

Many beetles and their larvae eat soft-bodied insects, like aphids, scale insects, and mites. The photo shows a lady beetle larva preying on aphids.

Spiders prey on a wide variety of insects. The photo shows an orb-weaver spider on its web. Tolerate spiders outdoors.

Other predatory insects include assassin bugs, green lacewings, and praying mantises, among others. The photo shows an assassin bug preying on an insect.

Parasitoid wasps and tachinid flies lay their eggs in or on an insect host. When the larvae hatch, they feed on the host insect.

The photo shows aphid mummies on a plant stem. A parasitic wasp laid its eggs on these aphids. The eggs hatched into larvae that fed on the tissue in the aphids’ bodies. Adult wasps then exited and continued their life cycle. Aphid mummies are evidence of natural enemies at work.

Some wasps lay their eggs on or in the larvae of other insects. Wasp larvae eat the insides of the host larvae. They then emerge on the outside of the host. The white structures in the photo are wasp cocoons. Adult wasps emerge from the cocoons and continue the wasp life cycle.

The photo shows imported cabbage moth larvae. Bt subspecies kurstaki products for butterfly / moth larvae help control this pest.

The photo shows Beauveria bassiana growing on an insect host. The infection kills the insect host.

Parasitic nematodes are tiny roundworms that exist naturally in soil. They parasitize many types of soil-borne larvae.

Green lacewing eggs are sold in containers. Purchase and bring the containers to your garden and scatter the eggs around your garden. Green lacewing larvae are predators of aphids and other insect pests.

Ladybugs are available at most garden centers. Ladybug adults feed on aphids and other insect pests. The photo shows a box of live ladybugs.

Praying mantises are insect predators as shown in the photo. They are available by mail order and in some garden stores. They consume all insects they catch, including other beneficial insects.

Attract birds to your landscape. They forage for insects in foliage. Provide a diversity of trees, shrubs, and herbaceous plants to support songbirds. Native plants provide rich habitat for songbirds. Birds also are attracted to fruits. Use bird netting to protect crops such as blueberries and grapes as needed.

Raptors such as the American kestrel shown in the photo eat insects, small rodents, and birds. Provide raptors with perches and nest boxes to encourage their activity.

Snakes, frogs, toads, bats, and many other creatures also feed on pests. For example, the garter snake shown in the photo preys on slugs, insects, and small rodents.

Domestic ducks eat slugs, snails, and insects. Be careful allowing ducks in your garden. They will eat seeds and seedlings. They will also eat established plants if left too long in one location.