Insects are possibly the most successful animals on earth. Half of the animals known to science - over one million species - are insects. They can be found in extremely harsh environments. From the Himalayas Mountains to the Sahara Desert, scientists have found trails of insects. Indeed, insects are everywhere! Butterflies, bees, ants, cockroaches, and beetles are all insects.

Adult insects have three parts in their bodies - head, thorax, and abdomen. The head holds insects' brain and mouth, as well as their sense organs such as eyes and antennae. Wings and legs are attached to the thorax segment. The abdomen segment contains insects' heart, digestive system, and reproductive organs. In addition to three body segments, adult insects also have three pairs of jointed legs, one pair of antennae, and, usually, two pairs of wings. A hard, external skeleton covers all parts of an insect's body for the purpose of protection. This external skeleton is called "exoskeleton." Young insects molt or shed all their exoskeleton several times before they grow to adult size. Once young insects become adults, they cannot grow any larger because their exoskeletons are formed.