Nature Gardeners : Beneficial Insects
Our gardens are heaving
with many creatures like insects, mites, spiders. To a new gardener every “bug”
is a likely suspect and tried to tackle the odd. As we study more about
gardening and that vague thing called “the balance of nature,” we discover that
very few insects are pests worth our concern. Most are either beneficial, of no
direct significance, or have a role yet to be understood fully.
Lady Bird Beetle (Adult) |
Most sprays, whether
organic or synthetic, tend to not discriminate between pests and beneficials.
When you spray the garden, pests will be killed but so will beneficial insects.
When you kill a beneficial insect you inherit its job. That lady beetle larvae
may be about to eat several dozen aphids. When it dies, controlling those
aphids and their thousands of potential offspring is now your job.
Most sprays, whether organic or synthetic, tend
to not discriminate between pests and beneficials. When you spray the garden,
pests will be killed but so will beneficial insects. When you kill a beneficial
insect you inherit its job. That lady beetle larvae may be about to eat several
dozen aphids. When it dies, controlling those aphids and their thousands of
potential offspring is now your job.
Lady bird beetle Larvae Feeding on Aphids |
In the old westerns it was
easy to tell the good guys from the bad guys. Good guys wore white hats; bad
guys wore black hats and were the ones shooting at the hero from behind those
rocks in the box canyon. Unfortunately bugs don’t wear hats, so we have to work
a little at learning who’s who in the garden. We gardeners would do well to
learn who these good guys are so we can monitor their presence and avoid
spraying unless absolutely necessary. Adult lady beetles (pictured), bees, and
praying mantids are familiar beneficial insects, but there are many more, such
as green lacewings, hover flies, ground beetles, and soldier bugs. And often
the immature stage of the “good guys” looks completely different from the adult
insect. (What appears to be a picture of a tiny alligator on a leaf is actually
a hungry lady beetle larva busy hunting down aphids.) Check out on-line
resources and garden books for pictures of all the life stages of the helpful
insects you’d like to welcome in your garden.
Attracting Beneficials
Beneficial insects are
part of the natural ecosystem. They can be “managed” in ways to encourage them
to stay around and increase in population. Here are four simple ways to attract
beneficial insects to our gardens and to make sure they stay around.
1.
Provide an accessible
source of water. A birdbath with some stones that stick up out of the water to
provide easy access for tiny beneficials or a periodic sprinkling will work
great.
2.
Plant flowers to provide
nectar and pollen for beneficial adults to feed upon. Species such as syrphid
flies and parasitic wasps need this for an energy source. Among the better
pollen food sources are plants that have umbrella-shaped bloom heads, such as
dill, yarrow, tansy, and fennel. Other plants to include are those with small
daisy-like flowers (such as chamomile and feverfew), and other blooming herbs
(thyme, oregano, rosemary). If you plant root vegetables, leave a few to go to
seed (carrots, radishes, turnips) as their blooms are also favorites of some
beneficial insects.
3.
Allow some pests to
remain as a food source for beneficial insects. Zero pest populations are not
sustainable and will leave beneficials with no reason to stay in your garden
area. Lady beetles are our friends but they are not philanthropic! They lay
eggs on plants with pests present so their babies can have food. No pests …
they move on. Just remember that it’s good to have a few pests around.
4.
Avoid pesticides that may
damage beneficial insects. This includes both organic and synthetic products.
And don’t spray indiscriminately. Before you use any pesticide, make sure you
have identified that a pest is indeed causing a problem and what type of pest
it is. When a situation warrants a spray, select a product with a narrow
spectrum of control (such as Bt that only targets caterpillars) to avoid
killing other insects. Choose one that breaks down fast when possible, such as
insecticidal soap or neem. Direct the spray only at the plants with the pest
problem.
Try these tips this
season and then take a few strolls out in the garden and give things a closer
look. You’ll see many species of beneficial insects helping you out by munching
on those pests that love to munch on the fruits of your labor.
Courtesy of the National Gardening Association, www.garden.org.
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