Why are there so many insects?

Entomologists believe that there are so many insects for a few reasons. Their exoskeleton provides protection, they are small, and most of them can fly. These traits help them escape from enemies and travel to new environments. Because they are so small they only need small amounts of food to survive and can live in very small cracks and crevices. Insects have lived on Earth a very long time. The oldest group of insects on Earth are the cockroaches, which first appeared some 300 million years ago.