Q.: I want to stop using pesticides in my garden. How can I attract some good insects to devour the bad ones?
A.: Nature is filled with “good” bugs, those crawling and flying insects that prefer a diet of pests that ravage vegetable and ornamental gardens. Using plants in your garden that they like for food and shelter will help attract them. They, in turn, will assist in keeping your pests in check.
Indiscriminate spraying of chemicals will kill both bad and good insects. To encourage the good bugs, stop using pesticides where they live and work.
Space is limited here to a brief overview of good bugs and insect pests they devour, and a general list of plants they desire. Beneficial insects include predators and parasitoids.
Predators are generally larger, faster and stronger than their prey and often capture and eat many individuals during their life cycle. They include beetles (larva and adult ladybugs, ground, rove and tiger beetles); flies (dragonflies, damselflies, and long-legged, robber, and syrphid flies); adult, egg and larva of green and brown lacewing and dusty wing; praying mantis; paper and sphecid wasps; true bugs (assassin, big-eyed, damsel, minute pirate, predatory stink, and wheel bugs); spiders (flower, green lynx, spiny orb weaver, and zipper spiders); and predatory mites.
Green lacewings are terrific in a garden. Although adults subsist on nectar, pollen and honeydew, each adult female lays 200 or more eggs on foliage then hatch into predatory larvae. Each will devour 200 or more aphids, mites and other pests during its two- to three-week development stage before spinning a cocoon. Five days later, an adult will emerge to mate and repeat the process.
Adult syrphid flies resemble small bees. They lay eggs that hatch into half-inch maggots resembling caterpillars. They feed on aphids, mealybugs and other pests.
Minute pirate bugs eat thrips, aphids, mites, scales, whiteflies and soft-bodied arthropods. Damsel bugs devour aphids, leafhoppers, plant bugs and adult and nymph caterpillars. Big-eyed bugs feast on leaf hoppers, spider mites, insect eggs, and nymph and adult mites.
Parasitoids are insects that live and develop as parasites, which kill other insects. They include flies such as tachinid fly, as well as braconid, eulophid, ichneumonid, and pteromalid wasps.
Tachinid flies are parasites of caterpillars (corn earworm, cabbage worms and loopers, armyworms, cutworms) and stink bugs, squash bug nymphs, beetles, and beetle and fly larvae. Adult females deposit eggs on foliage or in a host’s body, sucking fluids and killing the pest.
The stingers of parasitic mini-wasps do not sting but allow females to lay eggs in the bodies of insect pests, which hatch and kill them from the inside. Braconid wasps feed on moth, beetle and fly larvae, moth eggs, various insect pupae and adults (white capsules on caterpillars are cocoons and should be left alone). Ichneumonid wasps control moth, butterfly, beetle and fly larvae and pupae. Some parasitic wasps lay their eggs in moth eggs, killing the hungry caterpillars-to-be.
Learn to identify these six-legged garden helpers so you can readily distinguish them from the pests. There are lots of photo books for sale and in libraries. Photographs and information can also be found in Extension Service Offices and on the UGA CAES website.
Interspersing plants beneficial insects like among your edibles and ornamentals will attract help for whatever’s bugging you. If your garden lacks beneficial insects, some varieties can be purchased on the internet.
Preferred herbs include angelica, caraway, coriander, crimson thyme, dill, fennel, feverfew, lemon balm, parsley, pennyroyal, spearmint and tansy. Favored perennials are ajuga (carpet bugleweed), alyssum “basket of gold;” butterfly weed, cosmos “white sensation,” golden Marguerite, goldenrod “Peter Pan,” purple poppy mallow, Veronica spike speedwell, sweet alyssum; yarrow (common and fern-leaf); rudbekia (gloriosa daisy); and stonecrop sedums. Annual delights include marigold “lemon gem,” prairie sunflower, statice, zinnia “liliput” and even dandelion.
Be mindful this method may not solve all your pest control problems. If you need more help, order The 2013 Georgia Pest Management Handbook (commercial version-$30; homeowner handbook-$15) from the UGA CAES Office of Communications and Technology Services @ www.caes.uga.edu/publications/for_sale.cfm.