OF SOUNDS. 4(37 



269. 



By the friction of parts of the integument together, all those sounds 

 are produced which we observe in beetles of the different families. The 

 best known family in this respect, and which also produce the loudest 

 sounds of this description, are the Capricorn beetles. Almost all the 

 species of this very extensive group emit, upon being touched, a 

 tolerably loud, chirping, uniform sound, varying only in its intensity, 

 and which is produced by the friction of the posterior margin of the 

 pronotum upon the prolonged anterior portion of the mesonotum which 

 projects somewhat into the cavity of the prothorax. Both the surfaces 

 are very smooth, but not otherwise distinguished, so that the mere 

 mechanical friction of the one against the other must be regarded as 

 the sole cause of the sound produced. Indeed the same sound may be 

 produced after the death of the creature, by rubbing the two parts 

 together. Whether this sound have any determinate purpose, for 

 instance, attraction, cannot be decided with certainty, but thus much 

 is the case, that both sexes equally produce it, and, particularly, 

 only in such situations as affect their free and voluntary motion. I 

 have never found that any Cerambyx made it, unless disturbed or 

 touched, and precisely when those restraints were most violent the 

 sound was then loudest ; for instance, when impaled by a pin, and 

 he endeavoured with all his limbs to free himself from his thraldom. 

 The same is the case in all other insects which produce sounds by the 

 same means. We also detect similar sounds in the dung-beetles, viz. 

 in Geolrupes siercorarius, vernalis, Copris lunaris, and others of the 

 family of Lamellicorns, as in Trox sabulosus. The only difference is, 

 that these beetles produce it by rubbing the abdomen against the 

 elytra. Of this we may easily convince ourselves by taking such a 

 beetle between our fingers, and turning its belly upwards ; we then 

 distinctly see the up and down motion of the abdomen. The sound is 

 also prevented if a pin be introduced between the abdomen and the 

 elytra, so that the former cannot touch the latter. The burying beetle 

 (Necrophorus vespillo), the lily beetle (Lema merdigera, and another 

 species of this genus), even a swimming beetle (Hygrobia Herrnanni,) 

 and many others, produce similar sounds in the same manner. Indeed, 

 according to Latreille *, the Pimelias emit similar sounds by rubbing 



* Hist. Nat. torn. x. p. 264. 

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