What was the biggest insect on Earth?

A dragonfly that lived about 310 million years ago. The insect had a wingspan of 271/2 inches (69.9 cm)! That’s about the distance from the tip of your nose to the end of your arm. The biggest dragonfly today has a wingspan of less than 5 inches (12.7 cm).

Which is the meanest fly?

A kind of gall midge fly. Gall midge flies are born inside their mother’s body. Once born, they start eating her insides! In about two days they have eaten her whole body. The newborns then crawl out, leaving behind the hard, empty shell of the mother. Talk about rotten kids!

Which flies are like helicopters?

The hoverfly, bee fly, and flower fly. Most flies can only fly forward. But these three can fly forward and backward. They can even hover in place.

Are flies dirty?

Not all of them. Flies that live in dirty surroundings are dirty. A fly may walk around on rotting food, garbage, and other filth. Germs stick to its legs, mouth parts, and hairy body. Its legs alone may have over one million germs! If you see a fly near your sandwich, shoo it away. Flies that touch your food may leave harmful germs behind.

Do flies taste with their tongues?

No—mostly because they don’t have tongues! Flies taste with their feet. First they step on food. If their feet tell them it tastes good, they eat it. But flies can’t eat solid foods. They can only sip liquids. House flies and fruit flies soak up liquids with their mouth parts and then sip the liquid. Or they drop saliva on solid food, changing it into a liquid that they then drink. Sand flies, stable flies, and female mosquitoes have sharp mouth parts. They stab the victim and then sip its blood.

How did army ants get their name?

From the way they march along in huge troops of between 10,000 and 30,000,000 soldiers! Their feet make a loud rustling noise as they walk. Some people find this the scariest animal sound in the world. Army ants also give off a smell like rotting meat. Often they kill and eat other insects, spiders, or larger animals that do not escape in time.

Are ants strong?

You bet. An ant can lift a weight 50 times as heavy as its body. If you were that strong, you could pick up a car weighing nearly 2 tons (2.1 t)! Ants are also very fast walkers. The hotter it is, the faster they walk. Try shading some ants with a piece of cardboard on a hot, sunny day, and watch them slow down.

Do ants have good eyesight?

Most ants can see nearby objects very well. But some are blind. To survive, all ants depend on a good sense of smell. Ants smell with their antennae. Their antennae lead them to food and help them recognize friends and foes. Ants can live without seeing well. But if they lost their sense of smell, they’d die.

How do ants find your lunch in the park?

By smell. An ant finds a crumb you dropped. It carries the crumb back to the nest. As it goes, it presses its abdomen to the ground. This leaves a smell trail. Back in the nest, the ant pokes the other ants. They run out and pick up the scent. By instinct, they follow the trail. Soon there are dozens of ants looking for more lunch crumbs.

Do all bees sting?

No. Only female bees can sting. Also, some kinds of bees have no stingers. Some have stingers but don’t use them. A honeybee has a barbed stinger at the back of its abdomen. Usually the bee keeps it hidden, but it’s ready for use if needed. A honeybee stings when in danger. It plunges the stinger into the victim’s flesh. But as the bee flies away, the barbs hold fast. The stinger pulls out of the bee’s body—and the bee soon dies. Bee stings can be dangerous as well as painful. In the United States alone, about 40 people a year die from bee stings.

Why do honeybees make honey?

To feed the bees in their colony. A large colony of honeybees has up to 80,000 bees. They eat nearly 500 pounds (225 kg) of honey a year. Honeybees collect nectar from flowers and bring it back to the hive, or nest. Other bees place the nectar into six-sided cells, where it changes into honey. The bees eat some honey and feed some to the larvae. They store the rest for winter feeding or for rainy days. The stored honey is what beekeepers collect—and you eat.

How busy is a bee?

Very. A honeybee needs both nectar and pollen to live. To get these foods, the honeybee may visit 500 flowers in a single trip. The insect makes about 15 such trips on a sunny day, covering about 31/2 miles (5.6 km). A bee must collect nectar from about 22 million flowers to make 1 pound (0.5 kg) of honey!

What gives moth and butterfly wings their color?

Tiny, colorful, overlapping scales. Under a microscope they look like shingles on a roof. Some scales are colored red, orange, yellow, brown, black, or white. Others bend and scatter light, so they look blue, silver, violet, or green. The colors may blend in with a background and help hide the butterfly. Or they may stand out and scare enemies away. Often the colors are meant to catch another butterfly’s eye.

How can you tell a moth from a butterfly?

When at rest, a moth spreads its wings out flat to form a triangle. A butterfly holds its wings straight up, like sails on a boat. Moths have feathery antennae without knobs. Butterfly antennae are slender, with knobs at the tips. The bodies of most moths are thicker and furrier than those of butterflies. Moths fly mostly at night, while butterflies like sunlight and fly during the day.

Which insects live in your house?

The flies, mosquitoes, and ants you sometimes see, of course. But also many insects that keep out of sight. The holes in your wool sweater were probably made by moth caterpillars or beetle larvae. Your dog scratches to get rid of tiny fleas. Hidden in your bookcase may be “bookworms,” which are beetle larvae. And those fuzzy creatures you can find inside bad apples are the caterpillars of certain moths.

Do all insects go through metamorphosis?

No. A few, such as silverfish and springtails, simply grow bigger, much as you do. The newborns look just like their parents—except smaller. And from the time they hatch until they become adults, these animals hardly change their form or shape.

When do nymphs grow wings?

The time varies. Grasshopper nymphs take about two months. During this time, the nymphs keep eating, growing, and molting. With each molt, they develop bigger and bigger wings. After about five molts, the nymphs are full grown. Now they have wings, just like their parents do. Most dragonfly nymphs live in the water. Some take up to 5 years and 12 or more molts to become adults. They then crawl up out of the water, on plant stems. Soon they shed their final skin, open their wings, and fly away.

Do all insects pass through four stages?

No. Grasshoppers, crickets, termites, mayflies, cockroaches, dragonflies, and some others go through only three stages: egg, nymph, and adult. This is known as incomplete metamorphosis. The egg stage and adult stage are the same as in complete metamorphosis. Only the nymph stage is different. Nymphs have unformed wings, are smaller than their parents, and are often not the same color. The nymphs gradually grow bigger and develop wings and reproductive organs.

How long does the pupal stage last?

Anywhere from a few days to over a year. The pupae are forming new body parts. Many kinds of insects spend the winter as pupae and emerge as adults in the spring. As adults, the insects are ready to mate and start the whole process all over again: egg, larva, pupa, and adult.

What are pupae?

A stage of development when insects are protected by a case, or covering. Most pupae look lifeless, but inside the case many big changes are taking place. The pupae are slowly turning into adult insects. Larvae usually find well-hidden places in which to change into pupae. Beetle pupae can be buried deep in the soil. Most moth pupae are covered by cocoons. They might be hidden under a leaf or behind the bark of a tree. Butterfly pupae, called chrysalides (kruh-SAL-uhdeez), are usually attached to weeds or tree branches. Mud, stones, dead leaves, or rubbish protect some pupae.

What do larvae do?

Eat and eat and eat. One kind of moth larva eats 86,000 times its weight in the first two months of life. If you did the same, you’d put away 300 tons (305 t) of food! Day by day, the larvae grow bigger. Since their outer skins can’t expand, the insects molt. The young insects crawl out of the old skin. Then the new skin, which has been forming under the old skin, hardens. The insects may eat the skin they shed or leave it behind. It looks just like a real insect—except that it is hollow! After larvae have molted several times, they finally stop eating and molt for the last time. Now when the skin splits, they are in an entirely new stage of life. They are pupae.

What hatches from insect eggs in complete metamorphosis?

Wormlike or grublike larvae. Different species’ larvae have different names. The larvae of moths and butterflies are called caterpillars. The larvae of some flies are called maggots. You might see them on dead animals or decayed meat. Some beetle larvae are known as grubs. Mosquito larvae are called wrigglers.

What do insect eggs look like?

Most are round in shape and light in color. But they can also be long or short, have ridges or be smooth. The eggs of very small insects are so tiny that they can be seen only under a microscope. But the eggs of big insects can be up to 1/2 inch (13 mm) long. Insects lay their eggs either separately or in clumps.

What happens during metamorphosis?

Insects change. In butterflies, moths, beetles, flies, bees, wasps, ants, and most other insects, the change has four completely different stages: egg, larva (plural is larvae), pupa (plural is pupae), and adult. This is known as complete metamorphosis.

Do newborn insects look like their parents?

Not usually. Most newborn insects do not resemble the adults at all. In fact, they look so different that you can’t tell they’re the same species. When they grow up, all insects of the same species will look alike. But first, almost every insect passes through a number of stages. The process is called metamorphosis.

Do insects ever sit on the eggs they lay?

No, but the adults of a few species do stay with the eggs. In certain of these species, adults protect and feed the young for some time after they hatch. But most female insects lay their eggs and then either leave or die.

Where do insects lay their eggs?

In soil, on plants, in and on animal bodies, and in water. The place varies with the kind of insect. But each place supplies food to the insects that hatch from the eggs. For example, the female horse botfly sticks her eggs to hairs on a horse’s legs. The horse licks off the eggs. The eggs hatch and the young insects, called maggots, start to grow inside the horse’s stomach!

How are insects born?

Most hatch from tiny eggs laid by female insects. A few insects give birth to living young. These newborns hatch from eggs inside the female’s body.

Do insects fall in love?

No. But insects do have ways of finding one another. Some female moths and male butterflies give off a special odor. Male grasshoppers, crickets, cicadas, and katydids sing. Both sexes of fireflies produce flashing lights. Female mosquitoes whirr their wings. And some male insects give their mates tasty bits of food to eat.

Can insects harm you?

Fewer than 10 percent of all insects bite or sting humans. Yet insects can—and do—cause  enormous suffering. They can carry germs that cause yellow fever, cholera, typhus, and many other diseases. For example, every 10 seconds a person dies of malaria, a disease carried by certain mosquitoes. It is said that one-half of all human deaths throughout history were caused by mosquitoes. Insects can be big pests. They eat about 10 percent of all food and fiber crops. They also harm cattle and sheep by spreading disease among them. Farmers spend about $7 billion a year to control pesky insects.

Why don’t hibernating insects freeze to death?

The blood of several kinds of insects contains a kind of antifreeze called glycerol (GLIHSuh-rohl). This helps to keep them alive until warm weather returns. The African midge can survive the very lowest temperatures. One was dipped in liquid helium at a temperature of –452 degrees Fahrenheit (–269°C), and it lived!

What happens to insects in the winter?

Many have laid eggs by then and died. In the spring, the eggs hatch and newborns emerge. Others hide or hibernate in attics, cellars, barns, leaf piles, holes in trees, under bark, in caves, or in underground tunnels. While hibernating, the insects breathe more slowly and don’t eat. When warm weather returns, they become active again. Honeybees form big balls inside the hive. The bees on the inside shake and shiver to raise their body temperatures. The heat spreads out and warms all the bees. Some insects migrate for the winter. Monarch butterflies fly south about 2,000 miles (3,200 km). At the beginning of spring, they head north.

Which insects run the fastest?

Cockroaches. They can reach speeds of 21/2 miles (4 km) an hour. You may not think that is very fast. But at that speed they cover 40 body lengths a second. Compare this with human runners, who cover only four body lengths a second.

How fast can insects fly?

Faster than you can run! Yellow jacket wasps can fly 15 miles (24 km) an hour. That’s fast enough to catch you if you disturb a nest. Dragonflies are probably the fastest, at about 60 miles (96 km) an hour. A no-see-um midge holds the record for wing speed. It flaps its wings nearly 63,000 times a minute!

Which is the smallest insect?

The fairyfly. It is only about 1/100 of an inch (0.25 mm) long and is nearly invisible to the naked eye. In fact, the fairyfly is so tiny, it can fit through the eye of a small needle! Nearly 150 million of its eggs together weigh only 1 ounce (58 g).

Which is the biggest insect?

The Goliath beetle. At over 4 inches (10 cm) long, this insect is the size of a computer mouse! Also, it weighs nearly 1/4 pound (100 g). This makes it the heaviest insect as well. Another big insect is the Atlas moth. It has a wingspan of 12 inches (30 cm) from tip to tip. About 1 foot (30 cm) in length, the tropical walkingstick is the longest insect on record. If you include its legs, the insect measures 20 inches (51 cm). This stick insect lives in the rain forests of Borneo.

How do insects defend themselves?

Usually by escaping. They fly, run, or jump away. Many use camouflage. They blend in with their surroundings. Green caterpillars look like leaves. Gray and brown moths resemble the bark or moss on trees. When walking-stick insects sit on a branch, they look like twigs. The caterpillars that become giant swallowtail butterflies look like bird droppings. Some insects fight back. Ladybugs, stick insects, cockroaches, and certain beetles give off bad-smelling liquids when enemies come too close. Some ants and beetles bite with their powerful jaws. Bees, wasps, and some ants sting. Other insects have bright colors that warn away their enemies. Monarch butterflies taste bad, and birds have learned to leave them alone. Viceroy butterflies don’t taste bad, but they look like monarchs and this keeps them safe.

What eats insects?

Birds, frogs, lizards, skunks, anteaters, fish, and many other kinds of animals eat insects and insect eggs. Insects also eat other insects. Humans eat insects, too—like locusts, ants, caterpillars, and beetle larvae. There are about 500 kinds of insect-eating plants. Perhaps you know the Venus flytrap best. It can catch an insect in the blink of an eye! Then it slowly digests the unlucky bug.

What do insects eat?

Many different things. Butterflies, moths, flies, and mosquitoes are sucking insects. They feed on liquids. These insects use their mouth parts to suck up nectar and other fluids. Grasshoppers, crickets, beetles, and termites are chewing insects. They eat plants and other solid foods. These insects use one pair of jaws to cut off bits of food and grind them down. Another pair of jaws helps to push the food down the throat. A few insects, such as mayflies and some moths, never eat. That’s because their lives are over in just a few hours or days. These insects become adults, lay eggs, and die. Some insects are very heavy eaters. A silkworm eats enough leaves to increase its weight more than 4,000 times in just 56 days. A locust eats its own weight in plants every day. Just imagine eating your weight in food every day.

Do insects have tongues?

No. But insects have other ways to pick up various flavors. Butterflies, moths, bees, and flies taste with their feet. Ants, wasps, and some bees taste through their antennae. Crickets and some wasps taste with the tips of their abdomens to find a good place for laying eggs.

Do insects have a sense of touch?

Yes. Insects have a sense of touch that is far sharper than yours. Some of the short hairs that cover insects’ antennae and bodies are connected to nerves and are very sensitive. They pick up the lightest pressure—even a little breeze. The keen sense of touch helps most insects fly away before you can swat them. As soon as you move your hand, they feel the air moving. And away they go!

Do insects make sounds?

Yes. Many insects hum, buzz, or sing. But they don’t make sounds the way you do. They have no vocal cords. Whirring sounds come from rapidly flapping wings. Clicking and other sounds are made by rubbing body parts together—usually wing against wing or leg against wing. Male cicadas vibrate a thin skin on their abdomens. Their sounds can be heard for more than 1/4` mile (0.4 km). Sounds often help insects keep in touch with one another. But they’re also used to warn of danger or to woo a mate.

How do insects smell?

With antennae. The antennae of May beetles, for example, have 40,000 tiny pits. Each one is like a little nose for smelling. We wonder: If they catch cold, do they have 40,000 runny noses? Many insects give off special chemicals that only other insects can sense. Antennae let each kind of insect find food, tell friend from foe, and spot danger. Some male moths can find female moths that are up to 7 miles (11.2 km) away—just by their smell!

How do insects hear?

Not through ears like ours! Crickets hear through tiny openings on their front legs. Locusts, cicadas, and some kinds of moths and grasshoppers hear through little flat “ears” on their abdomens. Ants and mosquitoes hear with hairs on their antennae. Caterpillars receive sounds through hairs all over their bodies. All sound is made by vibrations in the air. Insects pick up these vibrations and hear very well—even without ears like ours!

Do some insects have extra eyes?

Yes. Most adult insects also have three tiny simple eyes called ocelli (oh-SEL-eye). You can find them between the two compound eyes. The simple eyes cannot form images. They help the insect tell light from dark.

How do insects see?

With two large eyes that can take up most of an insect’s head. Insect eyes are called compound eyes. Each compound eye is made up of many tiny lenses. A housefly’s eye, for example, has 5,000 lenses. But dragonflies take the prize, with 30,000 lenses in each eye! Insects can spot anything that is moving. Yet most don’t see very well. The world looks blurry to them. And since insects don’t have eyelids, their eyes are always open.

How do insects breathe?

Through tiny holes along their sides. Insects have no lungs. Instead, the air passes from the holes into a large tube. This tube divides into small tubes. The small tubes divide into still smaller tubes. These very tiny tubes bring oxygen to every part of the body.

Do insects have blood?

Yes. But the blood is usually not red like your blood. Insect blood is generally light green, yellow, or colorless. And it doesn’t flow through veins and arteries. The insect’s heart pumps blood through all the empty spaces inside the insect’s body. Slap a mosquito and you may see red blood. But that’s not the blood of the mosquito. It’s your blood—or the blood the mosquito got from another person or from an animal.

How do insects walk on six legs?

Easily. They move the front and back right legs at the same time as the middle left leg. Then they switch, moving the front and back left legs and middle right leg. This way they’re always balanced on three legs. Each of their six legs has five parts. Muscles attached to the thorax move the legs. Does it sound complicated? Be glad you have only two legs to worry about!

Are insects strong?

Very. Some have as many as 4,000 separate muscles. That’s a lot more than the 600 muscles in your body! A bee, for example, can lift a load 300 times its own weight. If you were that strong, you could pick up a 10-ton (10.2 t) truck!

Do insects have bones?

No. Instead, every insect has an outside skeleton, called an exoskeleton. Attached to the exoskeleton are the insect’s muscles. The exoskeleton protects the insect like a suit of armor. As the insect grows bigger, its exoskeleton gets too tight. It splits open and the insect comes out. This is called molting. Then, a new and bigger exoskeleton hardens around the insect. Molting occurs again and again, until the insect is a full-sized adult.

Skaters and Swimmers

In the calm water of ponds, deadly predators are on the move. Diving beetles scud through the shallows, grabbing small fish and insects with their sharp claws. Water boatmen hang just beneath the surface, waiting to stab flying insects that crash-land. On the surface itself, pondskaters wait for their victims, feeling for tiny ripples that pinpoint struggling prey. About one in 20 insect species live in watery surroundings such as ponds, lakes, rivers, and streams. Some spend their whole lives in freshwater, while others grow up in it and then fly away.

SURFACE TENSION
Instead of floating, pondskaters use surface tension to walk on water. Surface tension is a force that pulls water molecules together. When the water is calm, it makes the surface behave like a thin sheet. Pondskaters have light bodies and waterrepellent feet, so they can stand on the surface without sinking through it. This photograph, taken under a special light, shows how the water makes dimples around a pondskater’s feet.

WATER SCORPION
Although they live in water, most freshwater insects breathe air. The water scorpion gets its air supplies through a long snorkel, which it pushes up through the surface. The snorkel passes air to its tracheal system, which delivers oxygen throughout its body. Water scorpions are carnivorous bugs, and they stalk small fish and insects in muddy water. Their weapons are stealth, good camouflage, and two strong front legs that grip and spear their prey.

PONDSKATER
Seen from the side, this pondskater shows its piercing mouthparts and long slender legs. Pondskaters eat insects that have become stranded on the surface. They use their front legs to grip their food, their middle legs to swim, and their back legs to steer. Pondskaters are true bugs, and most of them have well-developed wings. They can fly, so it is easy for them to spread from pond to pond.

MAYFLY NYMPH
Mayfly nymphs that live in running water have flattened bodies and strong legs – features that prevent them from being washed away. Instead of breathing air from the surface, they collect oxygen through two rows of feathery gills. The nymphs spend up to three years underwater, preparing for an adult life that lasts less than a day.

GREAT DIVING BEETLE
With bodies up to 5 cm (2 in) long, diving beetles are powerful freshwater hunters. They swim with their back legs, speeding through the water. Before each dive, they store air under their wing cases, and they have to kick hard to stop themselves bobbing up to the surface. Diving beetle larvae are even more aggressive than their parents, with powerful jaws that can kill tadpoles and small fish.

SAUCER BUG
Like most freshwater bugs, saucer bugs are hunters, and they grip their victims with their front legs, which can snap shut like a pair of penknives. Saucer bugs lurk on the bottom of ponds, and their camouflage helps them to hunt. They surface to breathe, but afterwards they quickly dive back to the bottom, to hide among plants or in mud.

WHIRLIGIG BEETLES
Predatory insects often lie in wait, but whirligig beetles are always on the move. Like tiny black boats, they spin around on the surface, watching for small insects that have fallen in. A whirligig’s eyes are divided into two parts. One part looks above the surface, while the other part looks at the water underneath. This all-round view means that whirligigs can dive after food, and spot danger from above and below. Adult whirligigs spend the winter buried in mud at the bottom of ponds.

PHANTOM MIDGE LARVA
With its transparent body, the phantom midge larva is an almost invisible hunter. It hangs motionless in water, and snags small animals with its hook-shaped antennae. To change its depth, it adjusts two pairs of onboard buoyancy tanks, which make it rise and fall like a submarine. In summer, the adults often gather in dense swarms that look like clouds of smoke.

BACKSWIMMER
Hanging beneath the water’s surface, the backswimmer spends its entire life upside down. Like pondskaters, it eats insects that have crashlanded, but it attacks them from below. Its extra-long hindlegs work like a pair of oars, and it uses them to swim towards its prey. Backswimmers have big eyes, and they always keep their fronts towards the light. If they are put in a tank that is lit from the bottom, they swim the right way up.

DRAGONFLY NYMPH
Young dragonflies – known as nymphs – rely on stealth to hunt. They crawl along the bottom of ponds and lakes and up water plants, watching for prey. If a tadpole or small fish wanders near, they spear it with their telescopic jaws. The nymphs breathe by sucking water in and out of their abdomens. If danger threatens, they squeeze water out of their abdomens like jet engines – the perfect high-speed getaway.

Predatory Insects

Insects have many enemies, but the most deadly are often other insects. Some chase their prey in the open, while others use stealth, taking their victims by surprise. Some do not feed until their prey is dead, but praying mantises start straight away, while their meal is still struggling to escape. Predatory insects eat a huge range of small animals, including other insects, spiders, mites, fish, and frogs. Some of these are troublesome pests, so predatory insects can help to keep them under control.

HUNTING IN A PACK
When predators hunt together, they can attack prey much larger than themselves. These army ants are doing just that, as they swarm over a caterpillar. Army ants live in tropical forests, and pour over the ground like a wolf pack, overpowering anything that is too slow to get away. A single army can contain more than a million ants, advancing in a column up to 15 m (49 ft) wide. The ants have tiny eyes, so they find their prey by touch.

AMBUSHED!
For a praying mantis, a fly makes a tasty meal. Using her superb eyesight, this female mantis spots a fly, and then makes a lightning-fast attack. As she lunges forwards, her front legs open straight and then snap shut, pinning the fly between two rows of sharp spines. With the insect imprisoned, the mantis starts to feed. Male mantises are smaller than the females. When mantises mate, the female sometimes dines on her partner, starting with his head.

WASP STING
To make a kill, predatory insects have to overpower their victims. Many use their legs or mouthparts to grab their prey, but wasps often follow this up with a deadly sting. The sting slides out of the wasp’s abdomen, and a muscular pouch pumps venom through the sting and into the victim’s body. Unlike wasps, bees are not predatory. Their stings often have barbed tips, but they use them only in self-defence.

LIVING LARDERS
Some insects hunt on behalf of their young. This wasp has caught a spider, and has paralysed it with her sting. She will drag the spider back to an underground nest, where it will be a living food store for one of her grubs. There are many species of hunting wasps, and they specialize in different types of prey, from caterpillars to tarantulas. Only the females hunt – the males usually feed at flowers.

Dragonflies and Damselflies

Speeding over fields and ponds, dragonflies are some of the fastest-flying hunters in the insect world. They feed on other insects, overtaking their prey and then grabbing them in mid-air. There are about 5,500 species of dragonflies and damselflies, and all of them have large eyes, long bodies, and two pairs of transparent wings. Dragonflies usually rest with their wings held out, but damselflies fold theirs along their backs. Young dragonflies and damselflies live in freshwater, and take up to three years to grow up. During their underwater development, they feed on other animals, catching them with a lightning-fast stab of their jaws.

MID-AIR KILLER
With its strong wings and sturdy legs, this dragonfly is superbly equipped for ambushing and catching its prey. Inside its extra-large thorax are powerful flight muscles that beat its wings. Unlike most insects, a dragonfly’s wings beat in opposite directions, which means that it can fly backwards or hover on the spot. Dragonflies have very long abdomens, and people often imagine that they can sting; however, they cannot. Instead, dragonflies and damselflies kill their prey with their powerful legs and jaws.

HUNTING UNDERWATER
This dragonfly larva has caught a stickleback fish. It hunts by stealth, ambushing or stalking its prey. When it is close enough, it shoots out a set of hinged mouthparts, known as a mask. The mask is tipped with two spiky claws, and it works like a harpoon, stabbing and then pulling in the prey. Young damselflies are less powerful and eat smaller water animals.

HUNTING IN THE AIR
Adult dragonflies usually spot their prey by patrolling through the air. This dragonfly has just caught a meal, and has settled down to feed. It uses its feet to catch its prey, and also to hold it down as it starts to eat. Damselflies use a different technique – they either sit and wait for insects to fly past, or snatch them from waterside plants.

PAIRING UP
Dragonflies and damselflies have a unique way of mating – these two damselflies show how it is done. The male, on the left, grips the female behind the head, using a pair of special claspers on his tail. Meanwhile, the female’s tail reaches forwards to touch the male, so that her eggs can be fertilized. The mating pair can fly like this, and they often stay paired up while the female lays her eggs.

Insect Flight

Insects are some of the most impressive fliers in the animal world because of their small size. Dragonflies dart through the air after prey, and bees speed over fields and gardens in search of flowers. Hover flies can stay rock-steady in mid-air, while butterflies can migrate across entire continents. To do all this, insects use special flight muscles that power their wings. These muscles are packed inside an insect’s thorax, and they can work for hours without a rest. Large butterflies flap their wings slowly, so each wingbeat is easy to see. But many insects beat their wings hundreds of times a second, making them vanish in a blur. When wings move this quickly, they make the air vibrate. This creates a buzzing or whining sound.

POWER FOR FLIGHT
Some insects – including dragonflies – have flight muscles that are attached directly to the wings. But in more advanced fliers, such as wasps, they are attached to the thorax. These muscles work by making the thorax change shape. One set pulls vertically, making the top of the thorax move down. When this happens, the wings flick up. Another set pulls horizontally, making the wings drop back down. Once the wings start beating, the muscles carry on automatically until the insect decides to land.

BUTTERFLY IN FLIGHT
This time-lapse sequence shows a butterfly speeding through the air. Beneath it, a time bar shows how long each wingbeat lasts. Butterflies have four wings, but they beat like a single pair. Most of the push comes when the wings flick down, but because the wings twist slightly, some extra push comes when they flick up. In windy weather, butterflies are easily blown about, so they keep close to the ground.

WARMING UP
Insect flight muscles work best when they are warm. When the temperature drops below about 10°C (50°F), many insects are too cold to take off. But not all insects are like this. Bumble bees shiver to warm up their muscles – after a few minutes their flight muscles can be 20°C (68°F) warmer than the air outside. This Arctic bumble bee is feeding on flowers in Greenland, which is less than 750 km (465 miles) from the chilly North Pole.

UNDERCARRIAGE
Many flying insects use their legs to launch themselves into the air. This scorpionfly has taken off with a helpful kick. Scorpionflies are quite weak fliers, so they choose a high point from which to jump. Crickets and grasshoppers give a bigger push – once they are airborne, they can open their wings and fly away. During flight some insects fold their legs away, but many spread them out. This helps them to balance, and also makes it easier to land.

FLIGHT SPEEDS
Insects often fly in short bursts, which makes it difficult to measure their speeds. Many cruise quite slowly, but speed up if they are in danger, or if they are chasing their prey. This chart shows flight speeds for a range of different insects. At 58 km/h (36 mph), dragonflies can overtake most other insects, and even some small birds. However, they cannot keep flying at top speed for long, because their bodies begin to overheat.

Insect Behaviour

Compared to humans, insects have simple nervous systems, and their brains are often smaller than a full stop. But despite this, they have quick reactions, and they often behave in complex ways. All of them know how to search for food, how to escape danger, and how to track down a mate. Some can perform much more impressive feats, such as navigating their way across featureless sand or building elaborate nests. Insect behaviour is controlled mainly by instinct. Instinct is like a computer program that is built into an insect’s brain. It tells an insect what to do, how to do it, and often when to do it as well.

RAPID REACTIONS
The instant a house fly senses danger, it takes emergency action, and launches itself into the air. To do this, it relies on its fast-acting nervous system. The trigger for launch usually comes when its eyes spot movement overhead. Special nerves flash signals from the eyes to the insect’s flight muscles, powering up its wings. At the same time, the fly stows away its tongue and pushes up with its legs. By now, its wings are already buzzing, and in fraction of a second, it is on its way.

BRAINS AND MINI-BRAINS
Like all insects, this cockroach has a brain in its head, and a nerve cord that runs the length of its body. The nerve cord works like a data cable. It collects signals from sense organs and carries them to the brain, and it carries signals from the brain to the muscles. The nerve cord also has a series of ganglia (mini-brains) that control regions of the body, so parts of the body can work on their own. However, the brain is in overall command.

BUILT-IN CLOCKS
These two cockroaches have been caught on camera, feeding after dark. Like all insects, cockroaches cannot tell the time. Instead, their activities are controlled by a chemical clock that ticks away inside their brains. This built-in clock keeps insects in step with the world around them, and it makes sure that they come out at night. If cockroaches are kept in 24-hour daylight, they still come out at night, even though it is not dark.

INSECT REFLEXES
Clinging on to a potato stem, these Colorado beetle larvae look like easy targets for predatory birds. The larvae do not have wings, and their legs are small, so they cannot run away. But if anything touches them, the larvae carry out a simple but effective trick – they let go of the stems with their legs, and drop to the ground. Once the coast is clear, they slowly make their way back up the plant. This kind of behaviour is called a reflex. It can save an insect’s life, but it needs almost no brainpower at all.

INSECT INTELLIGENCE
Holding a pebble in her jaws, this female sand wasp is hammering shut the entrance to her nest. It is a remarkable piece of behaviour, because tool-users are practically unknown in the insect world. Once the nest is sealed up, the wasp puts the pebble back on the ground. Tool-using makes sand wasps look intelligent, but they are not quite as smart at they seem. When a sand wasp picks up a pebble, it is simply following its instincts. Unlike a human or a chimp, it does not understand how tools work.

Insect Senses

If insects were as big as we are, some of their eyes would be as large as footballs and their antennae would be up to 2 m (7 ft) long. Fortunately, insects never reach this size, but their senses play a vital part in their lives. For us, sight is the most important sense, and it is for many insects too. Most insects also have a superb sense of smell, and some can hear sounds more than 1 km (3⁄4 mile) away. Insects use their senses to find food, track down a mate, and avoid being caught.

COMPOUND EYES
Unlike vertebrates (animals with backbones), insects have compound eyes. A compound eye is split into lots of separate facets (units), each with its own lens. Each facet works like a mini-eye, collecting light from a small part of the view. Some insects have a few facets in each eye, but horse flies and dragonflies have many thousands. This gives them a detailed picture of their surroundings – although not quite as good as ours.

THREATENING GAZE
This horse fly’s compound eyes cover most of its face. Unlike our eyes, its eyes cannot move, but because they bulge outwards, it gets a good allround view. As well as compound eyes, many insects have three small eyes, or ocelli, on the top of their heads. These eyes each have a single lens. They register light levels, but they do not form a picture.

NECTAR GUIDES
Insects see fewer colours than we do – for example, they are not nearly so sensitive to red. However, many of them can sense ultraviolet light, a colour that we cannot see. Plants often use ultraviolet markings to attract insects to their flowers. These markings are called nectar guides. They steer insects towards the centre of a flower, so that they can collect a meal of nectar, and carry pollen from one flower to the next.

EARS AND ANTENNAE
Many insects communicate by sound, but their ears are not always on their heads. Crickets have their ears on their legs, while grasshoppers and moths have them on the sides of their abdomens. Moths use their ears as an early warning system, to listen out for flying bats. An insect’s antennae (feelers) are multipurpose sense organs. They can smell, touch, and taste, and they can also pick up vibrations in the air.

Insect Habitats

Wherever you are in the world, insects are not far away. They live in every type of habitat on land, from steamy tropical rainforests to the darkness and silence of caves. Many insects grow up in freshwater, and plenty spend their adult lives there as well. Some insects live along the shore, and a few even skate over the surface of the waves. Only one habitat – the ocean depths – is entirely insect-free.

COASTS AND SEAS

The coast is a difficult place for insects. Many live in dunes or on clifftop grass, but very few can survive in places that get soaked by salty spray. Beach insects include bristletails, which scuttle among stones and rocks. Long-legged bugs called sea skaters are the only insects that live on the open sea.

TEMPERATE WOODLANDS
Every spring, temperate woodlands burst into leaf, creating a gigantic banquet for insect life. Caterpillars chew their way through this tasty food, while predatory insects, such as hornets, harvest huge numbers of caterpillars and other grubs to feed to their young.

GRASSLANDS
The most numerous grassland insects are termites and ants. They scour every inch of the surface for food, collecting seeds and leaves and carrying them back to their nests. Dung beetles are particularly useful in this habitat. They clear up the droppings that grazing mammals leave behind.

FRESHWATER
Lakes, rivers, ponds, and streams teem with insect life. Mosquito larvae feed on microscopic specks of food, but some freshwater insects, such as water bugs, are big enough to kill tadpoles and even small fish. On the water’s surface pondskaters pounce on insects that have crash-landed, grabbing them before they have a chance to fly away.

CAVES AND MOUNTAINS
Caves are home to some unusual insects. Cave crickets are almost blind and use their extra-long antennae to find their way in the dark. Mountains are often cold and windswept, but many insects use them as a home. Beetles scavenge for food among rocks, while butterflies and bees pollinate flowers. High above the snowline, wingless scorpion flies scuttle about under the snow.

DESERTS
Compared to many animals, insects are well suited to desert life. Some of them feed during the day, but many wait until after dark. Desert insects include hawk moths, antlions, and giant crickets, as well as many kinds of ground-dwelling beetles. Some of these animals never have to drink, but this darkling beetle, from the Namib Desert, collects droplets of moisture from fog that rolls in from the sea.

TROPICAL FORESTS
The world’s tropical forests have more kinds of insects than all other habitats put together. They range from microscopic wasps to giant butterflies, like this Cairns birdwing, whose wings measure 28 cm (11 in) from tip to tip. In tropical forests, many bees and flies feed at flowers, while termites and beetles feast on rotting wood. Columns of army ants swarm over the floor, overpowering any other insects in their path.