The world of insects is rich and varied. By carefully observing the external structure of insects, we can get to know them better. Biologists have thoroughly described the structural features of the insect body through centuries of observations, and they divided the body into several different parts according to different functions and structures.
▲Legend: Anatomy of a Dragonfly
The body of every adult insect consists of three parts: head, thorax, and abdomen. The head contains the majority of the sensory organs such as the antennae and eyes, and of course the mouthparts as well. The legs and wings are on the thorax, so the thorax assumes all of the creature’s locomotive functions. The abdomen is the center of metabolism and reproduction; almost all of the insect’s internal organs are concentrated in the abdominal cavity. The excretory pores and external genitalia are located at the end of the abdomen.
While insects of the same class often have structural similarities, the differences between taxa can be significant, making identification easier. For example, the texture of the wings, the shape of the legs, the type of antennae, etc., can all be used to aid in identification.
▲Legend: A close-up of a butterfly
Wings are very important to insect taxonomy. Most winged insects can be classified into the correct order based on the appearance of their wings (see Appendix for details). Then we can further narrow it down by looking at other features to determine the category (order, suborder, family, etc.) to which it belongs.