272 INSECT ARTIZANS AND THEIR WORK 



but become louder as the summer advances, and so 

 die away again by degrees." 



What has been stated above must serve to illus- 

 trate the musical powers of the Orthoptera, which 

 are the leading songsters of the Insect World. Let 

 us glance at another order whose music has more 

 of the character of that produced by the drone of 

 the bag-pipes or by certain pipes of the organ. 

 The music of the bees — particularly of the Humble 

 Bees — has been understood generally to be due to 

 the rapid vibration of the wings. On the other 

 hand it has been contended that the sound is due 

 to the rush of air from the air-pipes {tracheae) 

 through the spiracles or breathing-holes that are 

 found at intervals along each side of the 

 body. 



There have been advocates and opponents of 

 each view, but, as often happens in other fields of 

 inquiry, the true explanation seems to lie between 

 the two. The spiracles of the thorax (the fore 

 body to which the legs and wings are attached) 

 open into an enlarged chamber, which is a dilation 

 of the air-pipe, and in which certain hard bodies 

 are vibrated which produce the sound ; the vibration 

 of the wings increases it. 



If one lifts the mossy dome from a surface nest 

 of Humble Bees in order to see what is going on. 

 several of the bees will throw themselves on their 

 backs in order to be in a good position to use their 

 stings on the intruder. In such a position there is 

 not much beating of the air by the wings, but 



