236 ] The Wonderful Ways of Insects and Spiders 



The silverfish illustrates still another type of growth. It has no 

 metamorphosis; the general body form does not change notice- 

 ably from the time it leaves the egg until it is fully grown. 



All insects shed their skeletal coverings a number of times 

 while they are still growing. 



How Insects See, Hear, and Feel 



EYES WITH THOUSANDS OF FACETS 



Occasionally among published photographs you may see 

 a strange-looking object suggesting a mosaic of diamonds. It 

 proves to be the compound eye, greatly magnified, of an insect. 

 The photograph makes a curiously intricate pattern of what are, 

 in effect, many tiny eyes set close together, somewhat like the 

 cells of a honeycomb. An adult insect has one of these compound 

 eyes on each side of its head. 



The six-sided areas into which the eyes are divided are known 

 as "facets." The compound eyes of ants and other insects that 

 live on the ground have only a few facets, and their vision is not 

 sharp. The eyes of dragonflies and other keen-eyed species may 

 have thousands of facets! 



There are also many species with simple eyes three of them 

 situated between the compound eyes. The simple eyes are so 

 tiny, however, that you will need a magnifying lens to find them. 



Insects can perceive mass and motion, light and darkness and, 

 to a certain extent, they can distinguish colors. 



EARS ANYWHERE AND EVERYWHERE 



Whenever hearing equipment has been discovered in cer- 

 tain kinds of insects, it has been found on rather unconventional 

 parts of the body. The grasshopper, for example, has an oval 

 membrane sensitive to sound, and it is located on the side of the 

 first abdominal segment. Crickets, ants, and katydids have hearing 

 organs on their front legs, and the male mosquito hears through 

 its antennae, or "feelers." 



