It's a Bug's Life
Insects are the largest single group of animals in the world. In fact, there are more insect species on earth than all other animals put together. About 750,000 different kinds of insects are known, and more are being discovered every year. And since they can live in all sorts of different kinds of places like on the ocean, in icy climates, hot springs, mountains and deserts, they have been around for over 350 million years.
Generally speaking insects are pretty small. Some are so tiny they can hardly be seen. That noted, a few rarer ones can grow bigger than some mice!
What is an Insect?
Insects have six legs, three on each side of their bodies. Insects also have one pair of feelers, or antennae, at the front of the head. Most insects have one or two pairs of wings and 2-3 sets of eyes. They have teeth in their mouths and their bodies are divided in 3 sections.
The Outside Skeleton is a tough outer coat that covers the insect like a coat of armour. It protects the insect from predators and wet/dry weather and extreme heat or cold. It also helps keep out germs and harmful chemicals and acts as a shock absorber.
Most insects have tiny hairs, or spines, growing out from the skeleton. Hairs are often also found on the legs, the antennae, and the mouthparts. An insect's blood is not red like ours – it’s usually clear or a yellowish or greenish color.
You might think spiders, scorpions and centipedes and millipedes are insects, but they’re not. Among other things, they have eight legs or more so they don’t fit into this group. The word “bug” is a common term people use to describe all sorts of creepy crawly critters that we tend to think of as pests.
Have you ever seen an insect wave its antennae around? It’s using them to feel, smell, and taste with its antennae. Some insects, such as the male mosquito, can hear with them too.
In some insects the feet, mouthparts, and hairs on the skeleton are also sensitive to smell. In fact, some insects are so sensitive to smell that they can smell more than a mile away!
How an Insect Sees
Insects have 2 compound eyes on the sides of their head. The eyes are made of many individual lenses called facets. The eyes of some insects have as few as nine facets each; the houseflies' have 4,000; some dragonflies' eyes have 28,000. Most adult insects have another set of eyes. These are two or three simple eyes, each with one lens and are located at the top of the insect's head.
Insects can see some colours but are nearsighted and can’t see an object clearly if it is farther than 2 or 3 feet away.
Taste and Feel
Tiny hairs on the mouthparts and the antennae help insects taste. Many insects taste with their feet as well.
The hairs on the insect's skeleton, feet, abdomen and antennae are very sensitive feelers that can sense vibrations and air currents.
Some insects have feel receptors on their wings that can sense that a solid object is approaching through the air. This is how a fly can sense that you are trying to swat it and why it darts away.
The Insect's Ears
Ears are found on different parts of the body in many different insects. For example, a grasshopper's ears are on the sides of the abdomen, underneath the wings. The ears are small, round disks that pick up sound vibrations and send them to nerves inside the body. There are simple ears near the tips of the antennae of many other insects. In many insects some of the hairs on the body are also sensitive to sound.
How Insects Make Sound
Insects don’t have voices like people. Rubbing one part of the insect’s body against another makes their calls or “songs”.
What Insects Eat
Insects eat many different kinds of material. Wood, paintbrushes, pepper, vinegar, wine bottle corks, wool, paper, flour, mushrooms, bits of meat, and decayed matter are only a few of them. Some bore into plants and suck their juice. Some bite off pieces of leaves and can strip a plant bare. Bees and most butterflies and moths sip nectar from flowers and eat pollen, without harming the plant.
Others such as the mosquito pierce the skin of other animals and suck drops of their blood for food. There are others, such as the cattle grub, that live inside another animal's body. Lots of insects lay their eggs right on the body of other insects and when the eggs hatch, the larvae start eating the insect.
Wings of flight
Insects were probably the first animals to fly. They developed wings many millions of years before there were birds or bats. They can hover and are able to move sideways or backward in flight. Most insect have 1 or 2 sets of very thin cellophane-like wings. They have many ribs, called veins. The veins help stiffen the wings. The wings of butterflies and moths are covered with scales and beetles’ wings are hardened and shell-like.
The wings of the housefly beat about 345 times a second. The wings of butterflies move much more slowly. They move only about 12 times a second. Insects also fly at different speeds. The housefly's speed is about 12 miles an hour. Hawkmoths have been clocked flying at 30 miles an hour, and some scientists say that dragonflies can fly even faster than that!
How Insects Protect Themselves
Insects protect themselves from their enemies in many ways. Some disguise themselves so that they blend into their surroundings. Many bees, wasps, hornets, and some ants protect themselves with poisonous stings - only females sting. Some insects like stink bugs, broad-headed bugs, and lacewings give off a bad-smelling chemical to drive enemies away.
How they live
Most insects live by themselves in crevices, in soil, under rocks, or under loose bark. On the other hand, ants, termites, most bees, hornets, and some wasps live together in colonies.
Why Insects are Important
Many insects are very useful to humans. Honeybees give us honey and wax. Silk comes from the cocoon built by the silkworm, the larva of a moth. Shellac is made from the substance given off by the lac insect.
Insects carry pollen from flower to flower as they flit about to gather nectar. This transfer of pollen helps plants produce fruit and seeds. Insects also serve as food for many birds.
ACTIVITY CODE: 101-1