Metamorphoses of Insects. 121 



body against another, and such have usually a special 

 hearing organ which in crickets and locusts is placed 

 under the knee on the outside of the foremost pair of 

 limbs. 



Development and Metamorphoses. Insects' eggs 

 have often a sculptured shell, and are laid in such 

 places as are suitable for the supply of food to the 

 newly hatched larvae. For this egg-laying the parent 

 has often an organ formed of the modified append- 

 ages of the abdomen. These organs are in the form 

 of bristles, pincers, or saws, and by these the insect 

 prepares the place for and deposits its eggs ; hence, 

 the organ is called an ovipositor. 



The young of most insects emerge from the eggs 

 as worm-like animals called caterpillars or larvae. 

 These are little jointed creatures, having a head which 

 bears eyes and a pair of antennae. Its mouth is armed 

 with strong jaws, and the surface is often covered with 

 bristles. Each of the three anterior segments of the 

 body of a caterpillar is usually provided with a pair of 

 little stumpy feet, and sometimes, as in the larvae of 

 butterflies, flies and saw-flies, the hinder joints have 

 also foot- like processes. Caterpillars are most voraci- 

 ous in their habits and grow rapidly, frequently moult- 

 ing or shedding their skin. On reaching the limit of 

 size, many caterpillars begin to spin for themselves a 

 case or cocoon. The glands from which this pro- 

 ceeds are two long tubes placed behind the head, but 

 opening on the lip, and the material of the cocoon 

 is silk. When caterpillars are fully fed they give 

 up eating, and their skin thickening they become 

 fixed and rigid and are known as pupae, or from 



