Control the bad with the good

February 4, 2008
Suzanne Wainwright-Evans
Pests Diseases

Are you looking for some extra help around your nursery to control pesky bad bugs? Help may already be there. On any given day, loads of beneficial insects and mites are crawling around your plants trying to help. The good guys are either predators or parasites. The predators are a little more general in their diet. They cruise around eating up a variety of pests. Parasites are more specific. They lay eggs inside of their prey, often leaving the dead body of their hosts behind. Both help to suppress a pest population as well as decrease the damage they may cause.

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To get these good guys to help you out, you can either help to conserve the ones you already have or you can attract them into your nursery from outlying areas. Some people buy beneficials, but it a major cost savings if you can use the ones you already have.

Conservation is essential

Conservation of native beneficials is essential if you want to grow in a sustainable way. Just because it’s crawling on your plant does not mean you have kill it. Ask yourself if this bug is eating your plants or protecting them. Make sure you have a proper identification of your creature before you go out to spray. If you find a pest that needs treatment, select products that are “softer” or less harmful to beneficials (like horticultural soaps or oils). These products kill on contact, and once dry, the good guys can move back in. If you need to spray a harder chemistry, and wonder how it will impact the good guys, you can always check at or These resources offer chemical compatibility tables where you enter the active ingredient and then a beneficial to see how the pesticide or fungicide will impact your good guys.

Attracting beneficials

If you're scouting and don’t seem to find as many beneficials as you would like, you can always try to attract them into your growing area. One of the key concepts to understanding this process is knowing that many beneficial predators and parasites rely on plant nectar and pollen as a part of their diets. If nectar and pollen are not present, many beneficials will not hang around to feed or reproduce. To introduce pollen and nectar into your nursery, add plants known to be sources of these essential foods. What should you plant? Most commonly you will see recommendations to install plants in the family Umbelliferae, like dill, Queen Ann’s lace or coriander. Because geographic regions have different growing environments, it helps to look regionally. Some universities compile more specific lists of plant material to help growers know which beneficial-attracting plants to use. One example is Michigan State University’s bulletin E-2973 “Attracting Beneficial Insects with Native Flowering Plants.” It provides a list of plants and their flower times, so you can have flowers all growing season. It is available free online at

Another helpful publication online is from ATTRA -- National Sustainable Agricultural Information Service. “Farmscaping to Enhance Biological Control” provides easy ways to enhance your native beneficials. It can be found at

If you can’t find the information you need online, check with your county extension service or state cooperative extension service.

Using the beneficials you already have in your nursery to help reduce pest pressures can be a great way to enhance a sustainable pest-management program. There are thousands of beneficials searching for food, so why not let them feed in your nursery? Remember to look before you spray, know what you are spraying and try to stick to the softer products that will have a minimum impact on the good guys. Also provide some nectar and pollen for beneficials that require it in their diet, and your beneficials will be quite willing to help you with your pest issues.

Don’t overlook these naturally occurring good guys

Up to 50 percent of the diet of the pink spotted ladybird beetle, Coleomegilla maculata, can be plant pollen. Be sure to provide pollen for them so the rest of the time they’ll eat your pests.

Flower flies are often mistaken for bees, but they are beneficials. Adults feed on nectar, but the larvae (that look like tiny caterpillars) are very aggressive predators on many pest insects.

Brown lacewings look very similar to the green lacewings. But, as adults, brown lacewings feed on pest insects while the green lacewing feeds on nectar, pollen and honeydew. The larval stage of both are very aggressive generalist predators.

Orius spp. can be found all over the United States. During its life cycle it can feed on spider mites, aphids and other soft-bodied insect and mites. It will also alternately feed on nectar and pollen.

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- Suzanne Wainwright-Evans 

pests diseases