Thanks to the discovery of the Rhyniella Praecursor, found in Scotland, we know that the history of insects began at least 400 million years ago. Thus, insects were the first animals to colonize terrestrial environments.
About 300 million years ago, insects began to conquer the air by developing wings. At the time, the dragonfly could have a wingspan of about 60 cm.
The process of insect specialization took place over millions of years. During that time, some species developed a complete metamorphosis and insects became more and more specialized.
Between 200 and 60 million years ago, the appearance of flowering plants allowed the birth of pollinating insects and, during the same time, a few insect species started to form colonies, creating the first form of social insect (i.e. ants, bees).
Today, insects are the most numerous animals (almost ¾ of the known species) on Earth. They have colonized every environment, and their total weight surpasses the weight of every other animal combined.