STRIDULATION OF INSECTS. o()l 



by two bands of a lighter colour. This last makes the least 

 noise of all the sound-producing species I have observed : you 

 can hardly hear the two or three cries he utters in calling the 

 female. 



I ought to observe, that the bow of the last named species, 

 seen through a magnifying glass, appears to me to be smooth. 

 If it really is so, the small shining plates folded on each other, 

 the edges of which form a kind of step, probably supply the 

 place of the indentations in the other species, and excite vibra- 

 tions in the treble string in their passage over it. 



The females of all these species seem to have smoother 

 bows, and less perfectly organized violins, than those of the 

 males. I think them mute, as far as regards us : I have never 

 heard them stridulate, though T have often seen them move 

 the thighs, as if they wished to sing. 



There are species wliich have only the rudiments of wings 

 and elytra, and in which nothing analogous to the musical 

 instruments just described can be perceived ; the bow in these 

 is also without indentations, which induces me to think they 

 do not possess the power of producing sounds. 1 have spent 

 some time in the neighbourhood of the mountain wliere one 

 species was exceedingly abundant, without hearing any stridu- 

 lation : this has confirmed me in the opinion expressed above. 



Stridulation may be excited in a dead locust, the articula- 

 tions of which have preserved their pliability; but the sound 

 produced is much fainter than that the insect makes when 

 alive, and at liberty. Amongst the species with weak voices, 

 it is not possible to distinguisli any sound resulting from the 

 movement of the thigh against the elytron. A sensation 

 however, similar to that which is produced by rubbing a rough 

 surface, is perceptible to the hand when moving the thigh. 



This must necessarily produce a sound, but it is too slight 

 for us to hear. The same difference between the natural 

 sounds, and those artificially produced, obtains in all stridu- 

 lating insects : it probably arises from our not knowing how to 

 manage the instruments, or to use them as the insects liit-m- 

 selves' do. 



Both locusts and grasshoppers make in flying a pretty loud 

 noise, which, however, is in no way connected with the stridu- 

 lation. This noise is their buzzing, and is produced, as in all 

 insects which possess the property, by the vibrations of the 



NO. IV. VOL. v. 3 A 



