Dangerous Sex

Dragonflies after sex

In the Carboniferous era, dragonflies already bore a close resemblance to today's dragonflies. During the past 300 million years, there was only one serious change in the body structure of these insects: the position of the reproductive organs.

Whereas in the dragonflies of the Carboniferous period they were located on the hindquarters, in today's dragonflies they are near the head. This has the serious disadvantage for today's male dragonflies that the risk of being eaten by the female partner during or after mating has increased significantly.

Evolutionarily, there must be an advantage in today's mating method, as otherwise the dragonfly's body has hardly changed at all. Eating males during or after mating is probably an evolutionarily advantage, as it is with spiders. The reason why spiders and dragonflies eat the male after mating is probably because the male is much smaller than the female and is therefore seen primarily as prey. 

When the earth's climate slowly became drier and cooler around 290 million years ago and the extensive tropical forests disappeared, dragonflies, like most insects, managed to adapt to the changes. Not only that: They developed new, smaller species and became even more numerous.

This is one of the reasons why insects represent one of the greatest success stories in the evolution of life. They are still around today. And the oldest fossil insects found, which are only a few millimetres in size, are over 400 million years old.