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10-09-03
Some Insects Deserve Bad Rap
Hating insects has been a human thing for hundreds of year -- maybe even
thousands of years. But not all insects deserve to be stuck with a bad-bug
label. Scientists tell us that most of the million or so different species
of insects cause little or no trouble for humans. But there are some species
that deserve to be called "bad boys of the bug world."
Generally, bad insects fall into one of two categories: insects that
harm us or insects that harm our things. Yes, when those brazen six-legged
creatures help themselves to something that we claim, they've crossed
the line. So we tag them with a special label. A four-letter word -- pest!
Scientists like to classify things. Most schemes used to categorize insect
pests have four groups. The insects that attack us are one grouping. The
insects that go for our things are divided into three groups: insects
that feed on our animals, insects that feed on our plants and insects
that feed on our non-living possessions.
By the way, that pest classification corresponds roughly with an ecological
description of insect food habits. Ecologically, insects can be categorized
as plant feeders, animal feeders or what are called decomposers, creatures
that feed on dead plant and animal stuff.
So what is the worst pest insect? Scientists have developed such lists
over the years. They use information like number and types of crops or
animals attacked, the amount of money spent to control the pest, or reduced
crop or animal yield.
Mostly scientists try to capture losses in dollars and cents, and the
insect with the highest sum wins the prize as the worst pest. This is
where things get sticky. How can you put a dollar value on human lives?
After all, some insects are responsible for human deaths, as a result
of transmission of disease-causing organisms. So different lists have
different worst pest insects.
The same is true of most of our personal worst insect nominations. To
crop producers, the worst insects are those that attack corn, soybeans
or apples. Livestock producers are more likely to nominate flies or lice
as the worst pest insects. An elevator operator will probably be more
concerned about insects that attack stored grain. In other words, the
insects that we are most concerned about are those that cause us the most
problems.
Most people do not produce crops and animals for sale, so their choice
for the worst insect might have to do with their lawn and garden. Many
homeowners would nominate the Japanese beetle during the summer months.
Now, however, with the appearance of the Asian ladybugs that are seeking
winter shelter in our homes, that insect would receive quite a few votes
for the most-hated list. But, for farmers, those ladybugs spent the summer
eating aphids on the soybean crop; the insect was actually beneficial
under those circumstances. As you can see, we all have our criteria for
what is good and what is bad.
However, the insect that will be on almost everyone's top-10 list of
worst pests is the cockroach. It seems everyone hates cockroaches, though
not always for good reason. To be sure, cockroaches, under some conditions,
can carry disease organisms. High cockroach populations can trigger allergic
reactions in susceptible people. But, mostly, we just hate cockroaches.
We hate them because they have the gall to move right into our homes a
feed on stuff that falls off our tables.
Ecologists tell us that cockroaches are nature's recyclers. But that
is little consolation for the homeowner who sees one in the kitchen!
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