By observing the heads of different insects, you can see the tools they use to cut, chew, pierce, suck, smell and taste food. These tools are called mouthparts. They also have unusual names like labrum, mandible, maxilla, hypopharynx and labium. The shape and arrangement of mouthparts differ from one group of insects to another. In some cases, certain mouthparts have completely disappeared.
You can tell what an insect eats by looking at its mouthparts. By looking at the shape of the mouthparts and the way they work, chewing insects can be differentiated from sucking insects.
In some species, adults do not even have working mouthparts.