Head
The head is where the eyes, mouth and antennae are found. Large compound eyes are a shared characteristic of most adult insects. The eyes are multi-faceted, meaning their surface is made up of numerous adjacent planes and not round. Some of these same bugs have simple eyes, as well, which are called ocelli. These are most often found above or between the multi-faceted eyes. Some bugs do not have the compound eyes at all, but rather have one or more simple eyes on each side of the head. There are some insects that do have any eyes.
Thorax
The front, middle and back are the three portions that make up the thorax. Each of these sections sport a pair of legs, which are jointed. If the bug is a flying insect, the thorax is where the wings will be found. There will usually be one pair of wings on each side. The thorax also houses the most powerful muscles found in a bug because it needs these to operate its legs and wings.
Abdomen
Several similar segments join together to make up the abdomen of a bug. This is usually the most visible section of a bug's body, and it contains the bug's digestive system. The reproductive organs are also found in this section, and if it is a bug that stings then the stinger will be found here, as well. The abdomen gets larger as the bug feeds and receives nutrients.