There are more insects in the world than any other kind of animal species. In fact, 95% of the species in the world are insects. Scientists have labeled more than a million species. Many insects are tiny, but the largest insects can grow to be 20 inches long or more.
Instead of growing, like birds or mammals, insects go through different stages where they seem like completely different creatures. For example, a caterpillar hatches out of an egg, forms a chrysalis, and then becomes a butterfly. Changing from one stage to another is called metamorphosis.
All insects are made up of three parts: head, thorax, and abdomen; and they all have three pairs of legs growing from their thorax. When insects have wings, they usually have four. Insects are invertebrate – they have no backbone.
Instead of having a skeleton, insects have an “exoskeleton,” a hard layer on the outside of their bodies.