Like all dragonflies, the common darter has two large compound eyes consisting of thousands of individual eyes (ommatidia), giving it an almost 360-degree field of vision.
The ocelli (simple eyes) of dragonflies are simple light-sensing organs, often arranged in a triangle on the top of the head. In the common darter they are located in the black line close to the antennae.
The ocelli are responsible for light perception and spatial orientation. They enable the dragonfly to quickly distinguish between light and shadow.