7 Beneficial Insects
Danger lurks in a backyard garden. Aphids, cutworms, mealybugs and other pests are preying on your
vegetables and flowers. Who’s an organic gardener going to turn to for help? Forget nasty,
To conserve biodiversity, we need to work across all landscapes. Natural areas can offer sanctuary
for pollinators and serve as movement corridors. Yards and gardens have an important role to play
in making landscapes hospitable. Herbicide and pesticide application can harm already threatened
pollinators. Use of beneficial insects in controlling garden pests can help support native pollinators.
Gardeners turn to biological control for help and to reduce or eliminate the need for chemical
pesticides. These insects are the natural enemies of garden pests. The problem with broad
spectrum conventional pesticides is that they not only kill the “bad bugs,” they rub out the
“good bugs,” too. A garden without natural predators means a world of insects gone wild.
There’s nothing left to keep pest levels in check.
If effectiveness isn’t a good enough reason, maybe safe food will cause you to try insect
predators & parasites. Interest in organic gardening and a growing demand for pesticide-free
foods has exploded in recent years. Even carefully washed vegetables can still contain the
chemicals that were sprayed on them at the farm. Families want to know that the food they
eat is safe.
Test Your Knowledge
Praying Mantis Quiz
The answer is to take a common sense approach to pest control:
Determine your tolerance level. This level, called the economic threshold in
commercial farming, will vary greatly between gardeners. How much damage is a given
pest creating and what is it worth for you to get rid of it? Sometimes hand-picking a pest
or blasting it off a plant with water will suffice – and it’s free! Always remember: not all
pests cause enough damage to require action. Again, it’s a matter of common sense.
Let bugs do your dirty work. Release biocontrols, both as a preventative
and as a control measure. Also, attract natural predators to your garden by planting a
row or border of “insectary plants.” Fennel, calendula, coriander, dill, and cosmos are
all considered good plants for attracting beneficials.
But like any good commander, be aware of the effects
of your actions and try to minimize costs and casualties. If treatment is required, begin
with methods that are least damaging to natural controls and the environment.
Catalog of the 7 Beneficial Insects
Most of the beautiful adult lacewings feed on pollen, nectar, and honeydew.
Green lacewing larvae, however, are voracious predators. Nicknamed "aphid
lions," the larvae do an impressive job of devouring aphids by the dozens. Larvae
hunt for soft-bodied prey, using their curved, pointed mandibles to stab their victims.
Everyone loves a ladybug, but gardeners hold them in especially high regard.
Lady beetles eat aphids, scale insects, thrips, mealybugs, and mites—all the
pests gardeners despise. With lady beetles, you get more bang for your buck,
because both the adults and the larvae feed on pests. Lady beetle larvae look
like tiny, colorful alligators. Learn to recognize them, so you don't mistake them
Contrary to popular belief, it is not illegal to harm a praying mantis. But why
would you want to? Praying mantids can handle even the largest pests in the
garden. You need a good eye to spot one because their coloration and shape
provide them with perfect camouflage among the garden plants. When the
nymphs hatch, they're so hungry they sometimes eat their siblings. In fact,
praying mantids are generalist predators, meaning they're just as likely to eat
a helpful lady beetle as they are to catch a caterpillar.
Damsel flies use thickened front legs to grab their prey, which includes aphids,
caterpillars, thrips, leafhoppers, and other soft-bodied insects. Nymphs, too,
are predators and will feast on both small insects and their eggs. With their
dull brown coloring, damsel bugs blend into their environment quite well. They
look similar to assassin bugs but are smaller.
Don't overlook the ground beetles in your garden. Lift a stepping stone, and you
might see one skittering away. The dark-colored adults often have a metallic sheen,
but it's really the larvae that do the dirty work of pest control. Ground beetle larvae
develop in the soil, and prey on slugs, root maggots, cutworms, and other pests
on the ground. A few species will venture up a plant stem and hunt for caterpillars
or insect eggs.
Assassin bugs know how to take care of business. These true bugs use trickery,
disguises, or just plain brute force to capture a meal. Many assassin bugs specialize
in certain kinds of prey, but as a group, assassins feed on everything from beetles
to caterpillars. They're fun to watch, but be careful handling them because they
Syrphid flies often wear bright markings of yellow-orange and black and can
be mistaken for bees. Like all flies, though, the syrphids have just two wings,
so take a closer look if you see a new "bee" in your garden. Syrphid maggots
crawl on garden foliage, searching for aphids to eat. They're quite good at
squeezing in the curled up leaves where aphids hide, too. As an added bonus,
the adults will pollinate your flowers. Syrphid flies are also called hover flies
because they tend to hover over flowers.