Extension

Often, when gardeners think about insects, they think of pests. However, not every insect in the garden is a pest. In fact, many of the tiny creatures crawling, flying and buzzing around the landscape are working hard to help gardeners keep plants healthy.

Beneficial insects are sometimes known as garden heroes because of their important roles in the landscape. Some pollinate flowers, others break down dead plant material and many help keep pest populations in check by feeding on insects that damage plants. Less than 1% of insect species are considered pests, so it pays to get to know the good guys before reaching for an insecticide.

Some of the most helpful garden visitors include bumble bees, parasitic wasps, lady beetles, green lacewings, assassin bugs, spiders and praying mantids. Recognizing these creatures can help gardeners better understand the natural activity taking place in their landscapes.

Bumble bees are among the most familiar beneficial insects. These fuzzy pollinators visit a variety of flowers, transferring pollen as they move from bloom to bloom. Although their size and buzzing can be intimidating, bumble bees generally are not aggressive when left alone. Stings most often occur when a bee or its nest is disturbed, so give them space to do their work.

Parasitic wasps are another group of unsung garden heroes. Thousands of species help control insect pests, and many are so small they are difficult to see. These wasps lay their eggs in or on insect hosts. As the wasp larvae develop, they feed on the host, eventually killing it. Their targets include a variety of insects that can damage garden plants.

Lady beetles, commonly called ladybugs, are among the best-known beneficial insects. Both adults and larvae feed on pests such as aphids, mites and whiteflies. However, the larval stage often goes unrecognized by gardeners. Lady beetle larvae have elongated bodies with dark coloring and orange markings, and they may look more like tiny alligators than the familiar spotted adults. Rather than removing them, gardeners should welcome these hungry predators.

Green lacewings are another valuable ally. Adult lacewings feed on nectar, pollen and honeydew, a sugary substance produced by some plant-feeding insects. Their larvae, sometimes called aphid lions, are active predators that feed on soft-bodied pests, including aphids, thrips, whiteflies, leafhoppers, spider mites and mealybugs. Like lady beetles, lacewings can help naturally reduce pest populations.

Assassin bugs also earn their place among the garden’s beneficial insects. These predatory bugs feed on a variety of insects, including caterpillars and other potential plant pests. However, assassin bugs can deliver a painful bite if handled.

Spiders, including crab spiders, are beneficial predators, too. Crab spiders often wait among flowers and foliage to ambush unsuspecting prey. Spiders help control insect populations, although they do not distinguish between beneficial insects and pests; their contribution to the garden ecosystem makes them valuable residents.

Praying mantids are predators that capture flies, beetles, crickets, moths, grasshoppers and other insects. Mantids aren’t selective hunters and may eat beneficial insects along with pests. Their long development time also means they may not respond quickly enough to control rapidly growing pest populations.

Gardeners can encourage beneficial creatures by providing the food and habitat they need. Plant a variety of flowering plants that offer pollen and nectar throughout the growing season. Include plants with different bloom times to provide a steady food source and avoid unnecessary disturbance of areas where beneficial insects shelter and reproduce.

Protecting these natural allies also means being thoughtful about pesticide use. Many insecticides affect a broad range of insects, killing beneficial species along with the pests they are intended to control. Before spraying, inspect plants closely to determine whether a pest is present in damaging numbers and whether beneficial insects are already keeping it in check.

When treatment is necessary, choose a product appropriate for the target pest and follow all label directions. Some products, including certain formulations of Bacillus thuringiensis (B.t.), target specific insect groups and generally have less impact on many beneficial predators and parasites than broad-spectrum insecticides. Remember, product selection and application timing matter, so always read the label carefully.

Beneficial insects are also available for purchase from commercial suppliers, but gardeners can encourage many of these natural helpers simply by creating a welcoming landscape and minimizing pesticide exposure.

A healthy garden is more than a collection of attractive flowers and productive vegetables. It is a small ecosystem filled with organisms that interact in ways that support plant health. By learning to recognize beneficial insects and giving them room to work, gardeners can help nature do some of the pest management for them.

Learn more about protecting beneficial insects and other helpful arthropods in Oklahoma State University Extension’s fact sheet E-1023 - Conserving Beneficial Arthropods in Residential Landscapes.