Insects grow differently than do other animals. Due to the rigid exoskeleton on the outside of an insect body, it cannot gradually expand in size like vertebrates do. To become larger, an insect must periodically shed the old exoskeleton, expand in size, and then grow a slightly bigger exoskeleton than the one it just shed. This process is called molting. It can be illustrated with an example of an adult damselfly pulling itself out of its old skin.

The new flexible skin is expanded by pumping it up with air or water. After expansion, the new exoskeleton will harden and take on color. This process of molting may occur several times during the growth of an insect, depending upon what species it is. Once the insect becomes an adult, however, growth ceases.