NEIGHBORHOOD GARDEN FOR JULY 15

NEIGHBORHOOD GARDEN FOR JULY 15, 2006

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ONLY 3% OF INSECTS ARE DESTRUCTIVE PART #1

BY GEORGE EDGAR

Did you know that only 3% of the insects in your yard and garden are destructive? I was listening to a garden show on TV when the host asked the guest entomologist if this statement is true. The entomologist said it was. I was amazed so checked with two entomologists at the University of Nebraska-Lincoln and a County Extension Educator. They all confirmed that the statement is true.

The host then went on to ask why when he sprayed his plants with bug killer it seemed in a few days there were more insects there than when he started spraying. The entomologist said it was probably because he not only killed the bad bugs but also the beneficial natural enemies (predators and parasitoids) that normally keep them in check.

One entomologist told me that the other 97% of the insects can probably be classified as follows:

· Nuisance insects

· Neutral or incidentals

· Beneficials

A good example of a nuisance insect is the Boxelder Bug. This bug does not eat your plants, it does not bite you. When it gets into your home it does not eat clothes, drapes, or furniture. These bugs are just a nuisance and can be best cleaned up with a vacuum. Mini-vacs are a tremendous advance in household pest control technology. And no chemicals are needed. Many do not like these nuisance insects but they are not destructive.

Neutral or incidental bugs are just that. They exist in our environment but are not chewing on our plants, they do not transmit diseases, nor do they bite us or our pets. Some, like butterflies, can be very pretty and are prized for their aesthetic value.

The beneficial insects can be further classified as

· Decomposers, that break down organic matter, help turn yard and kitchen scraps into compost, and are necessary for the health of the soil in our yard and garden;

· Pollinators, such as bees, flies, beetles, and other flower-visiting insects;

· Predators and parasites, including lady beetles, green lacewings, syrphid flies, ground beetles, parasitoid wasps, and other insects that eat aphids, grubs, caterpillars, as well as other yard and garden pests. The parasitoids lay their eggs in, on, or near many undesirable insects, their eggs eventually hatching and the larva feeding on the host, soon killing it.

Fred Birdsall, a Colorado Master Gardener, and Carl Wilson, a horticulturist at Colorado State University Cooperative Extension, have written an article on “Growing Plants to Attract Beneficial Insects”. In this they say a gardener can grow plants in their garden that attract beneficial insects. “Adult lacewings, flower (syrphid) flies and parasitic wasps, for example, feed on flower nectar and pollen. Their young devour many of the insect pests that can make a gardener’s life miserable. Maintaining this workforce however means providing food for the beneficials AND tolerating a few insect pests.”** Whitney Cranshaw, Colorado State University entomologist has compiled a list of flowers used by beneficial insects. This list is contained in the same article. For a copy see website at the end. He has also written an article on “Managing Nuisance Household Invaders”.

It really bothers me when people get out the bug spray whenever they see any kind of insect. Or when people buy the four-step lawn program and/or put an insecticide on their lawn even though they do not have and never have had an insect problem.

I overheard a man tell a store clerk that he had just finished mowing his lawn and had many moths fly up as he mowed. He was sure they were laying eggs and they would destroy his grass. He asked for an insecticide that would take them all out. He had no idea what the moths were, if they were really laying eggs, and if they would injure his lawn. For years the only insecticide I have put on my lawn is Merit for grubs. The more insecticide you use the more you kill the beneficials and predators that keep the bad bugs under control.

There are a number of choices on how to control your garden pests. These include biological control, cultural control, mechanical control, and chemical control. Biological control involves the introduction or conservation of natural enemies including predators, parasitoids, and pathogens to suppress insect pest infestations. This approach includes applying an insecticide only when it will be most effective, and as selectively as possible, so as to promote the natural activities of the beneficial insects.

Cultural control is selecting plants that are less prone to serious insect problems. Also, it means practicing good sanitation in your garden as many insect pests can overwinter in plant debris, and using proper watering, fertilizing, and good growing practices so you have healthy plants.

Mechanical control is a great option and includes physically preventing certain insects from attacking your plants. Nets (row covers) over plants during periods of high pest activity and physically removing the insects and destroying them avoids chemical use.

Chemical control should be used only when needed and only as one component of your insect management plan. Remember, insecticides need to be used properly and always follow the instructions.

Next week in Part #2, I will have a list of references, and talk more about insects, and especially encourage you to Use the right insecticide, at the right rate, at the right time, on the right insect.

I want to thank Dr. Frederick P. Baxendale, Ph.D. for his excellent review and editing. Fred is a Professor and Interim Head of the Department of Entomology at the University of Nebraska-Lincoln, and a regular panel member of Backyard Farmer on Nebraska Public Television.

** “Growing Plants to Attract Beneficial Insects” by Fred Birdsall, Colorado Master Gardener, and Carl Wilson, horticulturist, Colorado State University Cooperative Extension. Copyright by CSU/Denver Cooperative Extension Master Gardener 1999-2006. For a copy go on the internet to http://www.colostate.edu/Deps/CoopExt/4DMG/phc/benefici.htm