Insect is a small, six-legged animal. Bees, ants, wasps, butterflies, cockroaches, ladybugs, fireflies, termites, and moths are insects. So are houseflies, dragonflies, mosquitoes, silverfish, grasshoppers, lice, crickets, walkingsticks, and fleas. The list could go on and on. If the scientific names of all the kinds of insects were printed in The World Book Encyclopedia it would take more than 6,000 pages to list them.
Scientists have described and named more than 11/2 million species of animals. Of these, about 1 million are insects. Scientists discover from 7,000 to 10,000 new species of insects every year. They believe there may be from 1 million to 10 million species still undiscovered.
Insects live almost everywhere on earth–from steamy tropical jungles to cold polar regions. They live high on snow-capped mountains, and in deserts below sea level. They can be found in caves deep in the earth, or flying high in the sky. Only in the oceans are few insects found. We are constantly at war with some insects. They annoy us, bite us, and infect us with deadly diseases. They attack our crops, our pets, and our domestic animals. They invade our homes, eat our food, and damage our property. But insects also have great value to us. They pollinate many of our crops, provide us with honey and other products, and serve as food for fish, birds, and many other animals. In fact, life as we know it could not exist if all the insects were to disappear.
Insects are among the most fascinating animals on earth. They smell chiefly with their antennae, and some taste with their feet. Many insects hear by means of hairs on their bodies. Others have “ears” on their legs or on the sides of their bodies. Insects have no voices, but some make noises that can be heard 1 mile (1.6 kilometers) away. Insects have no lungs, but breathe through holes in their sides. Some insects have no eyes, and others have five eyes or more. Many insects have enormous strength. An ant can lift a weight 50 times as heavy as its body. If a 175-pound (79-kilogram) man could do as well, he could lift more than 4 short tons (3.6 metric tons)–with his teeth. A flea can broad-jump about 13 inches (33 centimeters). If a human being could do as well, he or she could jump 700 feet (210 meters). Many insects do the same things we do. They build bridges and apartment houses. Some raise crops, and others keep “cattle” that they “milk.” There are also insect carpenters, papermakers, guards, soldiers, nurses, slaves, hunters, trappers, thieves, and undertakers. Some insects even go to war against one another. Many people think that such animals as spiders, centipedes, mites, and ticks are insects. But these animals differ from insects. For example, spiders have eight legs, and insects have six. A spider’s body is divided into two main parts, but an insect’s body has three. Most insects have wings and antennae, but spiders do not.
INSECT/The world of insects
The story of insects is a tremendous success story. Insects first appeared on earth at least 400 million years ago. Down through the ages, they have struggled endlessly to survive. During this struggle, insects have gradually developed an incredible variety of body forms and ways of life. They have adapted themselves to almost all types of living conditions. Insects have been so successful in their fight for life that they are often said to be the only rivals of humans for control of the earth. Today, there are at least four times as many kinds of insects as all other kinds of animals combined. The total number of individual insects is astonishing. Scientists estimate that the average number of insects for each 1 square mile (2.6 square kilometers) of land equals the total number of people on the earth.
