360 GOUREAU ON THE 



If we examine the posterior thigh of this locust, we shall 

 perceive that it is much worked. The internal and external 

 surfaces are each formed of a compartment of small shining 

 plates enclosed by a solid and elevated border. Along the 

 internal surface there is a furrow in which the leg is placed, at 

 the will of the insect. By the side of this groove, and against 

 the compartment before mentioned, a small protuberance may 

 be seen extending the whole length of the thigh, and striated 

 like a file ; this is the bow {archet) of our violin. 



It will now be easy to understand how the insect plays on 

 his instrument : he has only to pass the thighs against the 

 elytra, pressing them at the same time : in this movement the 

 bow rubs on the treble-string and excites sonorous vibrations 

 in it, which are propagated over the whole of the elytron, and 

 produce sounds livelier and louder in proportion as the move- 

 ment is more rapid, and the pressure more considerable. It 

 might have been supposed, that the spines with which the 

 shanks are furnished, might be of some use in assisting to 

 produce sounds ; for the inner row is well situated for action 

 on the treble-string. I have not, however, succeeded in satis- 

 fying myself that this is the case, and I have failed in obtaining 

 a stridulatory sound from insects, from which that part has 

 been removed. In the crickets and grasshoppers, the two 

 drums contribute to the production of sound : the bow of the 

 one sounds as well as the treble-string of the other. In the 

 locusts the bow is not capable of producing sounds; the violin 

 alone possesses the power. 



All the locusts, as I have before observed, are not equally 

 good musicians. Those which appear to me most noisy have 

 the side cover of their elytra formed of a transparent sonorous 

 membrane, divided into large compartments, enclosed by ele- 

 vated nervures, and their bow is furnished with deep indenta- 

 tions. Such are those above described, Biguttulum, &c. On the 

 contrary, the sounds produced by those which have opaque 

 elytra, with small divisions, and slightly produced nervures, 

 and the bow but little or not at all indented, are weak and infre- 

 quent. This is the case with the locusts with coloured wings ; 

 Acridlum cwruleum, Germanicum, Italicum, and another species 

 very common on the sand of the Iliione islands, the wings of 

 which are of a clear sky-blue colour, the body and elytra grey, 

 covered with a bluish powder, and having the elytra crossed 



