The World of Insects

A Tiny, Busy World

Look down at the ground on a sunny day. Among the grass and under the leaves, a whole world is buzzing, crawling and hopping. This is the world of insects.

Insects are the most common animals on the whole planet. Scientists have found more than one million different kinds, and they think there are millions more still waiting to be discovered! For every single person on Earth, there are huge numbers of insects.

Scientists who study insects are called entomologists. In this book, we will explore what makes an insect special, how insects grow, and meet some of the most amazing insects of all. Get ready to shrink down and step into their tiny, busy world.

What Makes an Insect?

Not every little crawling creature is an insect. So how can you tell? An insect has three special features.

First, every insect has six legs. Not four, not eight — always six. This is the easiest way to spot one.

Second, an insect's body is made of three parts. The front part is the head, where the eyes, mouth and feelers are. The middle part is the thorax, where the legs and wings join on. The back part is the abdomen, which holds the parts the insect uses to breathe and digest its food.

Third, insects have a hard outer shell called an exoskeleton. Instead of having bones inside like we do, an insect has its tough skeleton on the outside, protecting it like a suit of armour.

Many insects also have antennae, the feelers on their heads that they use to smell and feel the world around them. Lots of insects have wings too, which makes them the only animals without backbones that can truly fly.

So remember: spiders have eight legs, so they are not insects. Worms have no legs at all, so they are not insects either. Six legs and three body parts — that is an insect!

How Insects Grow

Insects do not grow up in the same way we do. Many of them go through an amazing change called metamorphosis, which means "a change of shape."

The most famous example is the butterfly. It begins life as a tiny egg, usually laid on a leaf. Out of the egg hatches a caterpillar, also called a larva. The caterpillar's job is to eat and eat and grow bigger and bigger.

When the caterpillar is fully grown, it forms a hard case around itself called a chrysalis (or pupa). Inside this case, something incredible happens. The caterpillar's body changes completely. After some time, the case opens and out comes a beautiful butterfly, with wings ready to fly.

This four-step change — egg, larva, pupa, adult — is called complete metamorphosis. Beetles, bees and flies grow this way too.

Some insects, like grasshoppers, grow in a simpler way. The young, called nymphs, look like tiny copies of the adults and slowly grow bigger, shedding their hard skin as they go.

Beautiful Butterflies and Moths

Butterflies are some of the most colourful insects in the world. Their wings are covered in thousands of tiny scales, like tiles on a roof, which give them their bright patterns.

Butterflies feed on a sweet liquid inside flowers called nectar. They sip it up through a long, curly tongue called a proboscis, which works a bit like a drinking straw and rolls up neatly when not in use.

Moths are close cousins of butterflies. Most moths fly at night, while most butterflies fly in the day. Moths often have feathery antennae and softer colours that help them hide.

Some butterflies make amazing journeys. The monarch butterfly travels thousands of kilometres each year, flying from one country to another to find warmer weather. That is a very long way for such a small creature!

Busy Bees

Bees are among the most useful insects of all. Many bees live together in a large group called a colony, inside a home called a hive. A single hive can hold tens of thousands of bees, all working together.

A bee colony is wonderfully organised. There is one queen bee, who lays all the eggs. There are thousands of worker bees, who collect food, build the hive and care for the young. As they fly from flower to flower, bees collect nectar to make honey.

But bees do something even more important than making honey. As a bee visits a flower, a yellow dust called pollen sticks to its fuzzy body. When the bee flies to the next flower, some of that pollen rubs off. This is called pollination, and it helps plants make seeds and fruit.

Without bees and other pollinating insects, many of the fruits and vegetables we eat would not grow. So the next time you see a bee, remember — it is doing one of the most important jobs in nature.

Amazing Ants

Ants are small, but they are mighty. Like bees, ants live together in huge groups called colonies, and they work as a team.

An ant colony usually lives in a nest, often underground, with tunnels and rooms. There is a queen who lays the eggs, and thousands of worker ants who find food, dig tunnels and look after the young.

Ants are famous for their strength. An ant can lift things many times heavier than its own body — it would be like you lifting a car! They also talk to each other by leaving smell trails. When one ant finds food, it leaves a scent so the others can follow the path straight to it.

Some ants are farmers. Certain ants grow tiny gardens of fungus for food, while others look after small insects called aphids almost like we keep cows, gently collecting a sweet liquid from them.

Beetles, the Biggest Group

If you could line up every kind of insect in the world, beetles would be the biggest group of all. There are more kinds of beetles than any other animal on Earth — hundreds of thousands of them!

You can spot a beetle by its hard wing cases. A beetle has two strong covers on its back that protect a pair of delicate flying wings tucked underneath. When a beetle wants to fly, the covers lift up and the real wings unfold.

Beetles come in every size and colour. The bright red ladybird, with its black spots, is a beetle, and it is a gardener's friend because it eats tiny pests. The dung beetle rolls balls of animal dung to feed its young, helping to clean and feed the soil. Some tropical beetles are as big as your hand!

Why Insects Matter

Insects might be small, but our world could not work without them.

They pollinate flowers, so plants can grow and make food. They are food for many other animals, including birds, frogs, fish and bats. They help clean up the world by eating dead leaves, fallen fruit and animal waste, which keeps the soil healthy. Some insects even make things people use, like honey from bees and silk from silkworms.

Sadly, in many places there are fewer insects than there used to be. We can help by planting flowers, leaving wild corners in our gardens, and not using harmful sprays.

What We Learned

We have explored the tiny, busy world of insects! Let's remember what we found.

An insect has six legs and three body parts — a head, a thorax and an abdomen — with a hard shell on the outside. Many insects grow through metamorphosis, changing shape completely, like a caterpillar turning into a butterfly. We met colourful butterflies, busy bees, mighty ants and the beetles that make up the biggest group of all. And we learned that insects are vital to our world, pollinating plants, feeding other animals and keeping the soil healthy.

Next time you see a little bug, take a closer look. You are watching one of the most amazing creatures on Earth.

Want to discover more about the living world? Travel back in time with Dinosaurs A to Z, or plunge into the ocean in Explorers of the Deep Sea.