Insects also have become so successful because they all eat different things. They all have different mouth parts, so when they go eat they have different food. Therefore there is enough food for all insects.
My last reason why insects have become so successful is because they have an exoskeleton. The exoskeleton helps protect them head to toe from predators.
During the cockroach investigation I learned the difference between male and females. I learned that males have two bumps on there head, where as females don't.