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Updated Jul 16, 2022

SUPPORT FOOD WEBS AND ATTRACT NATURAL ENEMIES

The photo shows a predatory beetle preying on aphids on a leaf. Take steps to attract predators of insect pests. They can help keep insect pests on your plants at bay.

Jump To

  1. Plant a Diverse Garden To Attract Natural Enemies
  2. Learn to Recognize Natural Enemies
  3. Use Microbial Insecticides and Parasitic Nematodes as Needed
  4. Consider Purchasing and Releasing Natural Enemies
  5. Attract Animal Predators to Your Site
Plant a Diverse Garden To Attract Natural Enemies

Build habitat with native and non-native plants to attract wildlife and beneficial insects with plant selection. 

Native plants are good plant choices for attracting natural enemies. See resources:

Goldenrod flower with a wasp (natural enemy) and a native bee (pollinator)

Signe Danler, Oregon State University

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).

Plant debris providing good insect habitat

Signe Danler, Oregon State University

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

Native yarrow (Achillea millefolium) hosts a variety of insects

Marc Pascual, Pixabay

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.

Learn to Recognize Natural Enemies

Natural enemies of insect pests on plants include insect predators, parasitoids, or pathogens.

For more information, see A Pocket Guide to Common Natural Enemies of Nursery Crops and Garden Pests in the Pacific Northwest  (OSU Extension Service).

PREDATORS KILL AND EAT PESTS

Lady beetle larva eating aphid

Winston Beck, Iowa State University, Bugwood.org

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.

Orb-weaver spider in web

David Cappaert, Bugwood.org

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

Assassin bug eating prey

Whitney Cranshaw, Colorado State University, Bugwood.org

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

PARASITOIDS

Parasitoid wasp laying egg in insect host

Tim Haye, Universität Kiel, Bugwood.org

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

Aphid mummies on leaf

David Cappaert, Bugwood.org

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.

Braconid wasp eggs on outside of moth larvae

David Cappaert, Bugwood.org

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.

Use Microbial Insecticides and Parasitic Nematodes as Needed

The materials listed below are classified as microbial pesticides.

  • Bacillus thuringiensis (Bt) is a microbial pesticide. Bt acts as a stomach poison when insects eat treated plants. Bt products harm only specific kinds of insects. Read the package label and follow the instructions for best results.
  • Pathogenic fungi such as Beauveria bassiana and bacteria such as Bt (Bacillus thuringiensis) kill a variety of insects.
  • Spinosads are extracts derived from soil-dwelling organisms that also kill a variety of insects. Spinosad is toxic to bees.
  • Parasitic nematodes are also available as natural pest-control products. Purchase the right type of nematode for the pest.

Read and follow the instructions for best results and to minimize risks.

Imported cabbage moth larvae on leaf

Whitney Cranshaw, Colorado State University, Whitney Cranshaw, Colorado State University, Bugwood.org

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

The fungus Beauveria bassiana on insect host

Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, Bugwood.org

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

White grub larvae killed by parasitic nematodes next to two healthy larvae

Whitney Cranshaw, Colorado State University, Bugwood.org

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

Consider Purchasing & Releasing Natural Enemies
  • You may be able to increase the numbers of insect predators by releasing them in your greenhouse or garden.
  • Ladybugs, green lacewings, and praying mantises are common insect predators available for purchase.

Tips for Success with Purchased Beneficial Insects

  • Release of insect predators is used for pest control in greenhouses and other enclosed areas.
  • Green lacewings are a recommended method for azalea lacebug control.
  • However, when released outdoors, the insects may not stay in the treatment area.
  • Release beneficial insects before pest damage is significant. The positive impact may be limited when they are released after insect pests are noticeable and damaging plants.
  • Provide habitat for beneficial insects. Plant flowers and leave untended areas with standing foliage.

 

Green lacewing container

Whitney Cranshaw, Colorado State University, Bugwood.org

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.

Packet of lady beetles for purchase

Dekayem, CC BY-SA 3.0, via Wikimedia Commons

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 mantis eating prey

Chris Horne, Bugwood.org

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.

More about Purchased Ladybugs

Purchased ladybugs may not be native to the Pacific Northwest. These non-native ladybugs outcompete native ladybugs. This situation could contribute toward the decline of native ladybug populations.

Attract Animal Predators to Your Site
  • Animals such as birds, bats, reptiles, and amphibians eat pest insects.
  • Encourage animals by creating habitat.
Huttons vireo

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.

American kestrel on branch

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.

Garter snake coiled in straw

Kevin D. Arvin, Bugwood.org

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.

White ducks on grass

Copyright-free from piqsels.com

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.

Content provided by writer Signe Danler and editor Weston Miller.

 Peer reviewed by OSU Department of Horticulture.

Signe Danler

Signe Danler

I support the OSU Extension Master Gardener Program by teaching and managing the online Extension MG training course. I use my experience and training in home horticulture, ecological landscaping and urban forestry to create and teach modules on many subjects for home gardeners. I also design residential and commercial landscapes, specializing in regenerative gardening and landscaping practices.

Photo of Weston Miller

Weston Miller

Project Founder and Content Writer

Weston Miller served as Community and Urban Horticulture faculty for Oregon State University Extension Service for Clackamas, Multnomah, and Washington Counties. Weston is an author for content for this website. He developed funding partnerships with Portland area agencies to initiate and build out the Solve Pest Problems website focused on this goals: