Many people think that “bugs” is a word that describes all insects, but this is not the case. Only one group of insects can be called bugs, and the correct term for them is “true bugs.” Insects, part of a larger grouping known as arthropods, make up more than half of all animal species on Earth, and some—such as dragonflies—have been around since before the time of the dinosaurs. To study them better, scientists organize insects that share key features into groups, called orders. Butterflies and moths are just one of the seven main orders shown here.