Beneficial Insects
Insects are not only essential for healthy
ecosystems like streams, forests and meadows, but many insects are
very useful for human activities too. There are some insects that
create things that people like to use!
Insects are useful for
food and clothes! You might think you have never used
insects as food but remember where honey comes from!
Honey is made by bees from the nectar they collect from
flowers. Nectar is mostly sugar and water. They have a
special stomach for collecting the honey nectar. When
they return to the hive, the other bees take the nectar
and mix it with special chemicals called enzymes, and
then store it in wax containers. The honey is an
essential food source for the hive. Of course the flower
doesn't produce this nectar for nothing! While gathering
this essential food source, the honeybee also collects
pollen which is transferred to other flowers. This is
called pollination and many plants depend on insects for
this essential process. |
Many insects produce silk (shown
below), but silk worms produce massive amounts of silk
when they build their cocoons. In fact, if unraveled,
the silk from a single cocoon can be a mile long! Silk
worms are not worms at all but the caterpillars of the
silk moth Bombyx mori (shown to the right).
Originating in China, people have been using silk from
this moth for thousands of years.
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| There are other insects that we can use
to help control "pest" bugs rather than using
chemicals.
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Farmers can benefit from insects that
prey upon crop pests (bugs that eat the farmers plants)
and from insects that feed on weeds that would otherwise
choke their fields. Using insects, instead of pesticides,
to control crop pests, is called BIOCONTROL. In the
1880s, the citrus (orange)industry here in California was
under attack by a Scale
Insect called the Cottony Cushion Scale. Although
biocontrol has been used for centuries, this was the
first major success in large scale agriculture. A beetle
was found, the VEDALIA beetle from Australia, which was
able to bring the pest under control. |
Despite the massive
success of this and similar projects, the next century
saw the increased use of pesticides like DDT.
In the 1960s more and more people became concerned that
pesticides were having extremely bad effects on the
environment, that they were dangerous for the workers who
had to spray them on the plants, and that the insects
were becoming resistant to the chemicals. An excellent
book for learning more about this is Silent Spring by
Rachel Carson.
Today Integrated Pest Management (IPM) is seen as the
most effective way to combat insect pests. This method
uses moderate chemicals as well as biocontrol insects.
Although biocontrol is an excellent method for
controlling insects without putting chemicals into the
environment it has its drawbacks. The biocontrol insect
is usually introduced from another part of the world so
it has no natural predators or parasites in its new
habitat. It may then spread from the area where it was
released and start attacking insects that are not pests.
Whatever method is used, chemical, biocontrol or IPM, its
important that scientists and farmers are very careful
about their choices and the good and bad points are
carefully considered.
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You can use biocontrol
in your own backyard! Many plants are attacked by
Aphids,
small green bugs. They pierce the plant with
their needle like mouthparts and suck the nutrients from the plant.
Fortunately, ladybugs love to eat these bugs. Encourage the ladybugs
in your backyard. You can discourage pests like aphids without killing
ladybugs by spraying your plants with very dilute dish detergent.
If you find any ladybugs, put them on your plants! |
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