How Insects See.

New Zealand Tablet, Volume XXX, Issue 20, 15 May 1902, Page 15

How Insects See.

Nearly all insects have one pair of compound eyes, with which our young folks are familiar aB the large, bulging, glistening objects on the sides of the heads. In the dragon-fly, grasshopper, and even the common house-fly, these eyes are very conspicuous. You recognise this organ at once as an eye ; but when you come to examine it with a pocket microscope, or even very carefully without any magnifying aid, you readily see that this eye is very different from that of larger animals. The surface is divided into a large number of six-sided divisions, called facets. We see that what at first appeared to be a single eye is really an organ composed of hundreds — yes, in many cases even thousands — of eyes, and is therefore called a compound eye. In addition to this pair of large compound eyes, there are, in many full-grown insects, simple eyes, in number from one to four, between the compound eyes. The most common number is three, so arranged that imaginary lines connecting them would form a triangle. It ia supposed by scientific people that ' these simple eyes are useful in dark places and for near vision.' It is very difficult for ua to understand how things appear to an insect with the many parts of the compound eyes pointing in every direction. Just try to imagine yourself flying through a room and seeing the four walls, floor, and ceiling all at the same tune and equally well. And yet the insect probably doean't see anything aa clearly and distinctly as we do.