20 



AA^ ECONOMIC ENTOMOLOGY. 



more than likely there is also a sense of hearing connected with 

 them. In some of the nocturnal moths they are broadly feath- 

 ered or pectinated, much more prominently in the male than in 

 the female. It is believed that the reason for this is that the 

 insects are compelled to find their mates entirely by the sense of 



Fig 



Tip of the mouth of a lapping fly, showing the pseudo-trachea on the inner face of the 

 lips. Much enlarged. 



smell. That it is not food they seek is proved by the fact that 

 where these feelers are most developed the mouth parts are often 

 entirely aborted and the insect takes no food at all. Certain 

 " carrion beetles," also nocturnal in habit, are attracted for long 

 distances to their food, and, even where purposely hidden, they 

 find it without difficulty ; proving that the sense of smell alone is 

 used. It may be convenient to consider here a few of the com- 



