The Homeowners Column

The Homeowners Column

Not all bugs are bad

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

The good, the bad and the bugly. Despite common horror show depictions not all bugs are bad. The likelihood of one crawling into your ear and sucking out your brains is pretty remote. To some the only good bug is a dead bug. However we rely on insects much more than we realize. Some insects are directly beneficial to people by pollinating an estimated 30% of the foods we eat. Pollinators go beyond the classic honey bee to include native bees, wasps, flies, moths and butterflies. Other beneficial insects include predators or parasites of other insects that harm us or our plants. A tiny percent of insects are actually pests to people and plants.

There are many unsung and often misidentified heroes of the garden world. Predator insects include ladybeetles, lace wing larvae, robber flies, and even the tiny pirate bugs. These are the lions of the insect world as they "stalk" unsuspecting aphids and caterpillars.

Some of the best beneficial insects for controlling pests are the parasitic wasps. The adult wasps seek out the eggs or larvae of specific insects (many times crop eating caterpillar pests). The wasps then lay their eggs in the pest. The wasp larvae develop inside the pest. Eventually the pest dies and the adult wasps emerge. I'll bet you thought the movie Alien was just science fiction.

The good news is we can help the good guys in our gardens with some simple techniques.

First learn how to recognize common beneficial insects. A great reference is the laminated card set "The Good Guys! Natural Enemies of Pests" available through UI Pubs Plus 800-345-6087 or 217-333-2007 https://pubsplus.uiuc.edu/

Minimize or eliminate insecticide applications. Many insecticides will kill beneficial as well as pest insects. Even natural botanical insecticides such as rotenone can kill beneficial insects.

If insecticides are chosen as a control method, use selective insecticides. Selective insecticides are toxic to specific pests and will not directly harm beneficial insects. The microbial insecticide Bt sold as Dipel and Caterpillar Attack are toxic only to the caterpillars that feed on the sprayed plants. Insecticidal soaps can also be effective on pest insects without harming beneficials.

Build it and they will come. Include a diversity of plants in the landscape. Include annual and perennial flowers, native grasses and plants, ground covers, shrubs and trees.

Plant a variety of flowers with various flower shapes and sizes and include lots of native plants. Exotic plants will provide nectar and pollen; however, native plants will attract more beneficials. Pollinators are not the only insects that benefit from a variety of flowers. Many predators and parasites feed on pollen and nectar or use flowers to supplement their food supply if they run low on pests. Plants in the carrot family and mustard family are especially attractive to small parasitic wasps. Small flowered plants include as golden alexander, New Jersey tea, sweet alyssum, dill, fennel, garlic chives, lovage, coriander (cilantro) and white lace flower. Other popular plants for beneficials include: asters, great blue lobelia, columbine, wild bergamot, white wild indigo, blanket flower, coneflower, coreopsis, cosmos, tansy, yarrow, goldenrod, penstemon, sunflowers, yellow alyssum, sweet clover, buckwheat or hairy vetch.

Plan a season of bloom. Pollinators and beneficials need pollen and nectar from early spring into late fall. Gardeners enjoy having flowers all season as much as the beneficials.

Provide water areas with shallow dishes or pebble areas. The larger good guys, toads, will appreciate these areas too.

Include some permanent hardscapes such as stone paths and decorative rock. Allow a few bare areas of no vegetation near these hardscapes.

  • Repeat after me – "Not all bugs are bad. Not all bugs are bad. Not all bugs are bad."

Beespotter citizen scientist program http://beespotter.mste.uiuc.edu/

Visit the UI Pollinatarium on south Lincoln Avenue in Urbana, IL Fabulous indoor and outdoor displays about pollinators. 217-265-8302 uibees@life.uiuc.edu http://www.life.illinois.edu/pollinatarium/

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