Long before dinosaurs evolved, Earth was already buzzing with insects. The first insects were tiny, wingless creatures that lived on the ground about 400 million years ago.
Later they evolved wings and became the world’s first flying animals. Mastering flight made them incredibly successful and they evolved into thousands of new species.
Today, they make up three-quarters of all animal species on Earth.
FAMILY FACT FILE
■ Three main body parts: head, thorax (chest), and abdomen (belly and tail)
■ A hard, protective external skeleton (exoskeleton)
■ Three pairs of legs with joints
■ Two antennae (feelers)
■ Usually two pairs of wings
The first insects appeared in the Devonian Period, 396 million years ago.
■ When: 110–130 million years ago (Cretaceous Period) to now
■ Number of species today: More than 12,000 known
■ Diet: Everything from seeds and leaves to fungi and flesh
Ants evolved from wasps that began living in the ground in colonies. They were rare in the age of the dinosaurs but became very common later. Their huge colonies have a single breeding queen and hundreds of workers and soldiers, all of which are wingless females—daughters of the queen.
■ When: 100 million years ago (Early Cretaceous) to now
■ Number of species today: Nearly 20,000
■ Diet: Nectar, pollen
After flowering plants appeared 125 million years ago, some prehistoric wasps began to feed on flowers instead of preying on other insects, and these became bees. There are now thousands of different types of bee. Some are solitary, but many live in colonies with a single queen. Worker bees rear the young and collect nectar from flowers to store as honey.
DID YOU KNOW…?
When a bee feeds on a flower, a yellow dust called pollen sticks to its body. When it lands on another flower, the pollen rubs off and causes that flower to produce seeds. This process is known as pollination.
■ When: 230 million years ago (Triassic) to now
■ Number of species today: About 240,000
■ Diet: Fly larvae (maggots) mostly eat rotting matter and flesh. Adults eat various liquid foods from nectar to blood.
Many insects can fly, but true flies are a particular family of insect that have two wings rather than four. Instead of a second pair of wings, they have two tiny knobs that flick back and forth to stabilize flight. Flies appeared at the same time as dinosaurs. Some of the early fly species almost certainly pestered the dinosaurs, sucking their blood and feeding on their eyes.
■ When: 260 million years ago (Late Permian) to now
■ Number of species today: Up to 1 million
■ Diet: Anything from pollen and nectar to fruit, flesh, other insects, rotting bodies, wood, and animal dung
Beetles evolved from flying insects that once had two pairs of wings. The front pair turned into hard, protective cases that folded down over the rear wings to form a shield. The first flowering plants were probably pollinated by beetles. As flowering plants spread and evolved into new forms, so did the beetles. Today, there are so many species of beetle that they may well outnumber all other existing animal species combined.
■ When: 300–350 million years ago (Carboniferous Period) to now
■ Number of species today: Over 4,500
■ Diet: Rotten plant material
The first cockroaches looked much like those alive today. They scurried around on prehistoric forest floors, searching with their antennae (feelers) for dead plants. Termites evolved from wood-eating cockroaches that began living in colonies.
The best insect fossils are found in amber – a hard, golden material formed of ancient tree resin. Tree resin is a thick, sticky liquid that oozes out of wounded trees, often trapping insects such as these ants.