36 THE ENTOMOLOGIST. 



intended for the production of sound. The familiar sounds 

 of the Orthoptera have no claim to be regarded as a voice, 

 but are produced by rubbing one part of ihe body against 

 another. A few, but very few, of the Lepidoptera emit 

 sounds, which are made by rubbing the palpi against the 

 trunk, and cease if ihe palpi are removed. Auiong the 

 Coleoptera also sounds are generally produced by friction, 

 and the wings often produce a humming noise during flight. 

 In the genus Melolontha there is a second source of sound, 

 which may almost be called a voice. In the large trachea, 

 immediately behind each spiracle, is a chitinous process or 

 tongue, which is thrown into vibration by the air during 

 respiration, and thus produces a humming noise. Similar 

 structures occur in many Diplera, Ilymenoptera, Neuroptera 

 and Homoptera, and to them, even more than to the vibra- 

 tions of the wings, the characteristic sounds produced by so 

 many of these insects are ascribable. The "song" of the 

 Cicada, for instance, is thus produced by the metalhoracic 

 ganglia. In the Diptera and Libellulina it is by the four 

 thoracic spiracles that the sounds are produced, while in 

 Hymenoptera, as for instance in Bombus, the abdominal 

 sjiiracles are also musical. The sounds produced by the 

 wings are constant in each species, excepting where there 

 are (as in Bombus) individuals of very different sizes. In 

 these the larger specimens give generally a higher note. 

 Thus the male of Bombus terrestris hums in a', while the 

 large female is a whole octave higher. There are, however, 

 small species which give a deeper note than larger ones, on 

 account of the wing-vibrations not being of the same number 

 in a given time. Moreover, a tired insect produces a some- 

 what different note from one that is fresh, on account of the 

 vibrations being slower. Indeed, from the note produced 

 we can calculate the rapidit}' of the vibration. Thus the 

 house-fly, which produces the sound of F, vibrates its wings 

 21,120 limes in a minute, and the bee, which makes the 

 sound of a', as many as 26,400 times, or 440 times in a 

 second. On the contrary a tired bee hums on e', and there- 

 fore vibrates its wings only 330 times in a second. This dif- 

 ference is ))robab]y involuntary, but the change of " tone " is 

 evidently under the command of the will, and thus offers 

 another point of similarity to a true " voice." Thus a bee in 



