A DRAGONFLY has eyes so large that they cover most of the insects head. In common with other
insects, it has compound eyes made up of many
hexagonal facets, each containing a tiny lens. The iridescent eyes of the dragonfly are composed
of thousands of facets, ranging from 10,000 to 30,000 depending on the species.
It has been theorised that each of these tiny lenses records a small fragment
of the scene, and the insect sees the entire image as a mosaic. This is the mosaic theory of
insect vision first expounded by German physiologist Johannes Peter Müller in 1829.
And the dragonfly has such large eyes the better to see. Scientists believe
that it has the best eyesight among insects. The highly convex shape of the eyes gives this
insect a very wide angle of vision. Because of its good eyesight, a dragonfly can hunt until
very late into the evening.
The dragonfly's head is also extremely moveable, a further aid to vision.
The insect can turn its head sideways, and move it backwards, forwards and downwards. If you
have the opportunity, observe a