Dragonflies are the most eyed insects in the world. The eyes of dragonflies are large and bulging, occupying most of the head. There are three monocular eyes. The compound eyes are composed of more than 28,000 small eyes. They have excellent vision and can look up, down, forward and backward. without having to turn around. In addition, their compound eyes can measure speed. When the object moves in front of the compound eyes, each ommatidia responds in turn, and the speed of the target object can be determined after processing. This makes them the master bug catchers of the insect world. Its chewing mouthparts are developed and powerful.