232 OK TN'SECT SOUNDS. 



Distinguishing insect sounds by the mode in which they are 

 instrumentally produced, we may classify them as i. Stridulant 

 tones, as of a rasp or file, the stridulation being produced by the rapid 

 click of toothed processes. 2. Wing tones as simple vibration of 

 air. 3. Voice, as a reed tone essentially consisting of vibration of 

 membranes. 4. Noises, or interrupted concussion sounds, as 

 when parts of the body are struck against each other, or against 

 foreign bodies, or, as in some rare cases, air volumes expelled from 

 the interior of the insect ; or again, as in the clapping of wings in 

 certain acridia, and the rustle and din of a locust swarm. 



Before I enter upon the technical description and illustration 

 of the organs by which insect sounds are produced, a word may be 

 said upon the uses of these sounds. 



All are agreed — naturalists, poets, philosophers, and physiologists, 

 — that insect sounds, generally, are directly related with sexual 

 instincts. 



Dr. Hartman writes to a friend in June, 187 1, as follows. — 

 The drumming of the cicada is to be heard in all directions round 

 me as I stand in the dense chesnut forest : hundreds of males 

 hover about the height of a man from the ground, and I notice the 

 females assembling from everywhere. In my garden 1 observed 

 fift) larvae of cicada pruinosa which were brought up in a dwarf pear 

 tree, and I frequently saw females approach and set themselves 

 down in their neighbourhood, whilst the males uttered their 

 sonorous song. Darwin heard the sound on board the Beagle, a 

 quarter of a mile distant from the shore, and Captain Hancock 

 heard it more than a mile off. Darwin infers from his obser- 

 vations that the males enter into rivalry and competitorship, whilst 

 the females exercised selection according as their fancy was stirred ! 

 The same distinguished naturalist states that when the cricket is 

 alarmed at night he uses his voice to warn his neighbours. A 

 large number of observations made on ants and bees, and other 

 insects, may be found in his work on the Descent of Man. 



Herman Muller repeatedly observed the females of Mristalis 



