Jessica Davidson, Balclutha Primary School, asks :-

Are there blind insects?

Warwick Don, honorary curator in entomology at Otago Museum, responded.

The answer is, yes. At first sight (pun intended) this condition might seem harmful and would inevitably lead to extinction of the species. However, when the habitat and way of life are taken into account, it is clear that this conclusion is far from being the case.

Perhaps the best examples of blind or partially blind insects are to be found in caves. These insects, known as troglobiont species or the true cave dwellers, occur exclusively in dark caves and never in the outside world. Small eyes or even a complete loss of eyes, a reduction or total loss of body colour, and very long appendages (antennae and legs) are features of such species. The lengthened sensory antennae enable the insects to feel their way around inside the cave. Numerous beetle species belonging to the family Carabidae (ground beetles or carabids) are among the true cave dwellers.

Similar changes or adaptations are to be found in some subterranean (underground) insects. Several years ago the discovery of a new ant species (Martialis heureka) living in the Amazon rainforest was announced. Ant species new to science are being discovered on a regular basis. What is exciting about this particular discovery is that it shows features to be expected in a creature adapted to living in the soil – pale colour and loss of eyes. A number of other ant species also possess workers (wingless females) living under similar dark conditions that have either lost eyes or possess greatly reduced eyes.

It is important to realise that blindness is as much a product of the evolutionary process of natural selection as was the normal vision characteristic of the ancestral species that lived “on the outside”.