The Amazing World of Insects
BY AWAKE! CORRESPONDENT IN SPAIN
DO YOU think that insects are nothing more than a nuisance? Would you like the world to be free of these annoying pests? Do you spray them, swat them, or step on them at every opportunity? Before declaring war on every bug that crosses your path, why not try to learn something about their world? After all, with a population that outnumbers humans by about 200,000,000 to 1, you can be sure that insects are here to stay!
A brief look at just a few of these amazing creatures might well convince you that insects deserve your respect.
Masters of Flight, Marvels of Sight
Many insects are masters of flight. Consider some examples. Mosquitoes can fly upside down. Some can even fly through the rain without getting wet—yes, actually dodging the raindrops! Some tropical wasps and bees buzz around at speeds of up to 45 miles [72 km] per hour. One monarch butterfly of North America logged 1,870 miles [3,010 km] on its migration flight. Hover flies can beat their wings more than a thousand times per second—much faster than hummingbirds. Dragonflies can fly backward, a fact that has stimulated the curiosity—and close study—of researchers.
If you have ever tried to swat a fly, you know that these insects have exceptionally keen eyesight, which is coupled with a reflex that is ten times quicker than ours. Interestingly, the fly has a compound eye, containing thousands of six-sided lenses, each of which works independently. Likely, then, the fly’s view is broken up into tiny bits.
Some insects can perceive ultraviolet light, which is invisible to humans. Thus, what looks to us like a dull white butterfly is anything but dull to the male butterfly. Indeed, when seen in ultraviolet light, the female has attractive patterns that are ideal for grabbing the attention of courting males.
The eyes of many insects serve as a compass. Bees and wasps, for instance, can detect the plane of polarized light, enabling them to locate the sun’s position in the sky—even when it is hidden by clouds. Thanks to this ability, these insects can forage far from their nests and still find their way home unerringly.
Love Is in the Air
In the insect world, sounds and aromas are often used to find a mate—no small achievement if your life span is just a matter of weeks and prospective mates are few and far between.
Female emperor moths find a suitor by emitting a scent that is so potent that a male can home in on its source from nearly seven miles [11 km] away. His sensitive antennas can detect a single molecule of the scent.
Crickets, grasshoppers, and cicadas prefer to make themselves heard. Even we humans can hear the amorous cicada, as it converts its whole body into a sounding board. Why, a large group of courting cicadas can create a din that is louder than a pneumatic drill! In contrast, some females make no sound at all.
Waking Up and Warming Up
For humans who live in a cool climate, keeping warm is important. The same is true for cold-blooded insects that wake up each morning virtually frozen stiff. The sun is their ally, and they make the most of it.
Flies and beetles are attracted to flowers or leaves that bathe in the warmth of the sun during the early morning hours. Some beetles frequent Australian water lilies that act like botanical stoves, heating up their blossoms as much as 36 degrees Fahrenheit [20°C.] higher than the surrounding temperature. In contrast, butterflies have a built-in heating system. When they need to warm up, they open their wings, which serve as efficient solar panels, and incline them toward the sun.
You Name It, Insects Do It!
In the insect world, nearly every species has a different role, some of which are quite bizarre. Some moths, for example, seek life-giving salt and moisture by sucking the tears of buffalo. Other insects, equipped with a potent antifreeze, inhabit freezing mountaintops and spend their lives scavenging bugs that have succumbed to the cold.
As wise King Solomon observed thousands of years ago, the ant is particularly industrious. Solomon wrote: “Go to the ant, you lazy one; see its ways and become wise. Although it has no commander, officer or ruler, it prepares its food even in the summer; it has gathered its food supplies even in the harvest.” (Proverbs 6:6-8) The absence of a ruler is all the more remarkable considering that some colonies of ants may number upwards of 20 million! Yet, this insect “metropolis” functions perfectly, with each ant performing its specific task, so that the entire colony is supplied with food, protection, and housing.
Perhaps the most impressive example of insect housing is the termite mound. Some of them stand 25 feet [7.5 m] tall.a These marvels of construction come with sophisticated air-conditioning and underground fungus gardens. Even more amazing, the termites that build these towering pyramids are blind!
Why We Need Insects
Insects play a vital role in our daily life. Indeed, about 30 percent of the foods we eat depend on pollination by bees, most of which are wild bees. But pollination is only one of the useful labors performed by insects. Insects keep the earth clean by means of an efficient recycling system, as they reprocess dead plants and animals. Thus, the soil is enriched, and nutrients that are liberated can make things grow. “Without insects,” writes entomologist Christopher O’Toole in his book Alien Empire, “we would be inundated with dead plant and animal material.”
Insects are sorely missed when their work is not done. Consider what happened in Australia, which has become home to millions of cattle. Herds inevitably scatter dung everywhere. Besides being unsightly, the manure provided a breeding site for the bush fly—a plague to both humans and cattle. So dung beetles were imported from Europe and Africa. The problem was solved!
Friends or Foes?
Admittedly, some insects eat crops and carry disease. But only about 1 percent of the world’s insects are considered pests, and many of these do more damage because of the way man himself has altered the environment. The malaria-carrying mosquito, for example, rarely bothers the native people who live in the equatorial forest. It does wreak havoc, though, on towns bordering the forest, where stagnant water abounds.
Often, man can naturally control insect pests that attack crops, either by rotating crops or by introducing or conserving natural predators. Lowly ladybugs and lacewings effectively control plagues of aphids. And in Southeast Asia, public-health workers discovered that a couple of dragonfly larvae could keep a water-storage container free of mosquito larvae.
Even with their drawbacks, then, insects are an integral part of the natural world on which we depend. As Christopher O’Toole points out, while insects can survive without us, “we cannot survive without them.”
a For humans, the equivalent would be a skyscraper that stands six miles [more than 9 km] high.
[Box/Pictures on page 16, 17]
METAMORPHOSIS—A New Look, a New Life-Style
Some insects totally revamp their appearance through a process called metamorphosis—literally, “change in form.” The changes can be quite dramatic. Maggots change into flies, caterpillars into butterflies, and aquatic larvae into airborne dragonflies. Hundreds of thousands of insects undergo metamorphosis.
To produce such a transformation—comparable to converting a train into an airplane—huge modifications must take place inside the insect’s body. Consider the butterfly, for example. While the caterpillar is dormant in the chrysalis, most of its previous tissues and body organs break down and a whole set of new adult organs—such as wings, eyes, and antennas—develop.
Often, the transformation involves taking on a new life-style. For example, while in the larval stage, the dragonfly captures small fish or tadpoles; but when it becomes a free-flying adult, it changes its diet to insects. This is the equivalent of a man spending his first 20 years swimming in the sea and the rest of his life flying around like a bird.
Could evolution orchestrate these incredible transformations? How could a caterpillar simply appear on the scene, programmed to transform itself into a butterfly? For that matter, which came first—the caterpillar or the butterfly? One cannot exist without the other, for only the butterfly breeds and lays eggs.
Newly emerged from its pupa, the swallowtail stretches its wings
[Pictures on page 18]
Above: Pollen-eating beetle
Above right: A dew-covered leaf beetle warming up
Far right: Rhinoceros beetle
[Picture on page 18]
African short-horned grasshopper
[Picture on page 18]