Dragonfly head is large and concave behind. It is on the flexible and slender neck. The head is mostly covered by the pair of large compound eye. Dragonfly has small antenna which are hardly be noticed. All dragonflies have three ocelli. The labrum, mandible and labium form its mouth-parts. The dragonfly mouth-parts are very good at biting, adapted for predation.
Dragonflies have very large eyes and have very good vision. Vision dominates their behaviour, including predation and looking for mates. The compound eye is made up of ommatidia which is a visual unit consisting of a lens system and a group of light sensitive cells. A large dragonfly may have up to 30,000 ommatidia in each compound eye. Each ommatidium collects one visual information, together form a mosaic image in the dragonfly’s brain.