There are more kinds of insects than all the other animals put together. There are thought to be 200 million individual insects for every one of us. Insects’ success is down to their flexible armored covering which can take on almost any shape. Insects also show an amazing ability to develop new ways of living, such as forming complex societies.
Nothing illustrates insects’ physical flexibility better than Darwin’s stag beetle of Chile. While the female’s jaws are normally shaped and used for feeding the males jaws are longer than his body, serrated and curved. They are fighting weapons. Males battle high in the trees, each using his jaws to get a grip under his opponent’s wing cases, so he can lever him off the branch and hurl him to the ground, 100 feet below.
The most important thing insects developed from their armor was wings. They became the first creatures to take to the air and their wings allowed them to spread to almost every environment on earth.
The wings of the copper damselfly in France play a critical role in every aspect of it struggle to survive and reproduce. Males take to the air to fight; females signal their receptiveness to males using their colored wings. The damselflies escape spiders webs strung along their flight paths through the sheer power of their flight. Even when a female goes underwater to lay her eggs her wings trap a layer of air so she can breathe.
Wings allow one insect to undertake one of the world’s great migrations. Monarch butterflies that hatch in southern Canada in the autumn fly south 2000 miles to the Michoacan mountains of central Mexico. They use the sun as a compass to guide them. Up to a billion of them gather in a few selected spots where they hibernate crowded in the trees.
Some insects have turned parts of their bodies into chemical weapons. The bombardier beetle mixes harmless chemicals inside itself and they react at boiling point. The rear end of the beetle is shaped as a rotating nozzle. It can fire the boiling chemical in any direction at its enemies. The jet pulses 500 times per second, allowing the beetle’s rear end to cool just enough between each burst to prevent it cooking itself!
Many million years ago some insects began to care for their young. It was the first step towards developing today’s great insect societies, such as ants and honey bees. The Japanese red bug shows us what this first step may have been like. They feed on fruits so rare the young could never find them. So their mother searches the forest and drags fruit back to her nest.
Female fight and steal fruit from each other. The young of losing females may abandon their nest and take up residence with a more successful mother. The new mother’s increased work load eventually kills her. Her body is the young bugs’ last meal before leaving home.
Insects’ greatest society is the grass-cutter ants – their nest may contain 5 million ants. They march in columns across the grassland harvesting half a ton of grass each year and taking it back to their nest. Yet they cannot digest it. However the ants have become farmers, growing a special fungus found nowhere in the world but their nests. The fungus breaks the grass down and the ants eat the fungus.
Insects’ great societies are the closest things in nature to the complexity of a human city.