The use of beneficial insects to help manage their pest
relatives has been a mainstay among gardeners for a very long time. There
are a number of excellent advantages to this method of control:
• Requires a minimum of effort by the gardener.
• Helps prevent the development of pesticide resistance in target insects.
• Does not contribute to environmental pollution.
• Aids in maintaining a more natural balance in our ecosystem.
• Beneficial insects can often keep pace with pest populations.
We gardeners can attract and keep our natural friends in
our backyards and gardens by following these suggestions, many of which are
just good gardening sense that we use anyway.
PREVENTION: A STITCH IN TIME . .
Using good horticultural practices goes a long way to help prevent and/or
minimize pest infestations. As much as possible, use disease resistant plant
varieties. Keep your plants healthy by providing appropriate moisture,
drainage, and air circulation.
Dispose of severely diseased plants immediately by putting
them in a plastic bag in your regular garbage, not in the composting bin.
Avoid placing plants in the wrong areas by consulting other horticulturists
about what species and varieties thrive in sites with poor drainage,
compacted soil, or in other less-than-ideal locations.
Mulch properly, remembering to pull mulch back a little
from the base of trees. Avoid improper fertilization by having the soil
tested to see what and how much amendment it really needs. Adding more than
the needed amount of nutrients can backfire; for example, too much nitrogen
can actually encourage aphids and mites more than it helps the vegetation.
IF YOU FEED THEM, THEY WILL COME
. . .
The adults of many beneficial insects, such as bees, ladybeetles, hover
flies, parasitic wasps, etc., feed on the nectar and pollen produced by
flowering plants. Including such plants in the garden will help ensure that
these friends will stick around long enough to lay their eggs on your
Then, the larvae will consume aphids, caterpillars,
cutworms, thrips, and mites, among other bad guys. Plants that are the most
attractive to beneficials are those with small flowers arranged in clusters.
Families with these characteristics include:
Carrot (Apiaceae)—dill, parsley, fennel
Mustard (Brassicacea)—sweet alyssum, nasturtium, candytuft
Daisy (Compositae)—coneflowers, yarrow, daisies, goldenrod
The flowers of these plants provide easily accessible
nectar and a good landing strip.
Provide a continuous food supply by choosing a variety of
plants that bloom at different times during the growing season. Early
bloomers include alyssum and pansies while late bloomers are goldenrod,
sedum, and asters.
Also, water your crawlers and fliers along with your
vegetation. During extended periods of dry weather, place a sufficient
amount of small rocks or gravel in a bird bath to provide them a foot pad
from which to "drink" safely.
THEY’RE JUST LOOKING FOR A GOOD
Like any living thing, insects need shelter. We can provide
suitable shelter by
leaving some leaf litter in landscape beds and/or by periodically
replenishing mulch in landscape beds to give
ground-dwelling allies a place to hide when they need to. Ground cover
plants can provide not only a home but pollen, nectar, and prey for some
predators and parasitoids.
Places such as fence rows and windbreaks can also act as
a haven for friendly insects. In general, the greater the diversity
of plants in a landscape, the more likely that diverse types of beneficial
insects will establish "residency."
KNOW YOUR ENEMIES—AND YOUR
FRIENDS . . .
Beneficial insects are almost certainly already in your yard and
garden. Before using any pest control strategy, it is vital to identify
accurately what is REALLY causing the problem and what will REALLY remedy
it. County extension personnel, reference books, fact sheets, computer
resources, and other horticulturists can assist in this process.
Inspecting your plants about every two weeks will go a
long way in preventing and controlling enemy invasions. Frequent inspections
will enable you to find pests while they are still small or immature and not
quite so numerous. Catching them early often results in the use of non-toxic
of less toxic methods of control. Look for the friendly fellows, too. You
may discover that they are already providing all the control that your
CONSERVE, PRESERVE, PROTECT . .
Besides providing shelter and food, there are other ways to
ensure that beneficials continue to work for your garden’s benefit. Use
non-chemical controls when possible, including pruning, hand-picking,
covering plants with netting, etc.
If pest populations are overwhelming beneficials, consider augmenting them by purchasing and releasing more
beneficials. Once again, education is the key to success. Learning which
insects will be the most effective, when to release them, and how to maintain
them before and after release are crucial to achieving control objectives.
Also, avoid the used of bug zappers. Studies have shown that they kill more
desirable insects than pests.
USING CHEMICAL CONTROLS . . .
There are many valid reasons for using chemical controls:
excessive plant damage, time constraints, and economic impact are among the
many factors to consider. Because of potential environmental and personal
consequences, the appropriate, safe use of insecticides and other types of
pesticides cannot be overemphasized.
Know the product. Read the label. What does it kill? On
which plants is it safe to use? It is illegal to used a chemical control for
insects and on plants that are not listed on the label. Such use can harm
the plant and may not kill the target insect. Use only the amount and only
as frequently as directed on the label.
Use the least toxic chemical that will achieve the goal, such as
horticultural oils and insecticidal soap. Choose selective insecticides that
are toxic to a specific pest and are not directly harmful to beneficials. Bt
(Bacillus thuringiensis) for the control of mosquitoes is a good example.
Remember that beneficial insects are still insects. Broad spectrum
insecticides that wipe out a wide variety of pests will almost certainly
impact friendly critters, too.
Use selective application. This includes spot spraying and rotating areas
SUMMARY . . .
Relying on beneficial insects as a pest control method is not a
matter of sitting back and “letting nature take its course.” As with any
other effective gardening tool, it requires education, effort, patience and
awareness. We may need to give up some ideas about the perfectly groomed
yard and become willing to tolerate a certain amount of insect harm. Most
plants can put up with some damage without too much ill effect. The pay-offs
of observing and participating in a more naturally balanced ecosystem can be
well-worth the effort.