INSECTS U35 



preaching to a voice. Vocal sounds are produced by 

 the emission of air from the lungs variously modified 

 by the organs of the mouth. But no insect breathes 

 through its mouth; no air is expelled thence in a 

 single species; it is a biting, or piercing, or sucking 

 organ; an organ for the taking of food, or an organ 

 for offence or defence ; but never an organ of sound. 

 The wings are in most cases the immediate causes of 

 insect sounds. 



There is a pretty little beetle (Clytus), not un- 

 common in summer in gardens, remarkable for the 

 brilliant gamboge-yellow lines across its dark wing- 

 cases, which makes a curious squeaking sound when 

 you take it in your hand. You think it is crying; but 

 if you carefully examine it with a lens while the 

 noise is uttered, you will perceive that the cause is 

 the grating of the thorax against the front part of 

 the two wing-cases. Several other beetles produce 

 similar sounds when alarmed, by rubbing the other 

 end of the wing-sheaths with the tip of the abdomen. 

 Many of those genera which feed on ordure and car- 

 rion do this. 



But the noisiest of all insects are those of the 

 classes Orthoptera and Homoptera, the crickets and 

 grasshoppers, and the treehoppers. The locusts and 

 grasshoppers, it appears, make use of their hindlegs 

 in producing their crink. If you look at the grass- 

 hopper's leg, you will see that the thigh is marked 

 with a number of transverse overlapping angular 

 plates, and that the shank carries a series of short 

 horny points along each side. The insect when it 

 crinks brings the shank up to its thigh, and rubs 



