530 



NOISES OF INSECTS. 



of other insects, my farther observations will be Confined to the tribes 

 lately mentioned, the Gryllina, Slc, and the Cicada. 



No sound is to me more agreeable than the chirping of most of the 

 Gryllina, Locustina, he. ; it gives life to solitude, and always conveys to 

 my mind the idea of a perfectly happy being. As these creatures are 

 now very properly divided into several genera, I shall say a few words 

 upon the song of such as are known to be vocal, separately. 



The remarkable genus Pnumora — whose pellucid abdomen is blown 

 up like a bladder, on which account they are called Blaazops by the 

 Dutch colonists at the Cape — in the evening, for they are silent in the 

 day^ — make a tremulous and tolerably loud noise, which is sometimes 

 heard on every side.^ The species of this genus have a claim to the 

 name of Fiddlers since their sound is produced by passing the hind-legs, 

 which are furnished with a series of smooth elevated ridges, and may be 

 called \hQ fiddlesticks, over a number of short transverse elevated ridges, 

 of a similar though slightly different structure, on the abdomen, which may 

 be called the strings.^ 



The cricket tribe are a very noisy race, and their chirping is caused by 

 the friction of the cases of their elytra against each other. For this pur- 

 pose there is something peculiar in their structure, which I shall describe 

 to you. The elytra of both sexes are divided longitudinally into two 

 portions ; a vertical or lateral one, which covers the sides ; and a hori- 

 zontal or dorsal one, which covers the back. In the female both these 

 portions resemble each other in their nervures ; which running obliquely 

 in two directions, by their intersection, form numerous small lozenge- 

 shaped or riiomboidal meshes or areolets. The elytra also of these have 

 no elevation at their base. In the males the vertical portion does not 

 materially differ from that of the females ; but in the horizontal the base 

 of each elytrum is elevated so as to form a cavity underneath. The ner- 

 vures also, which are stronger and more prominent, run here and there 

 very irregularly with various inflections, describing curves, spirals, and 

 other figures difficult and tedious to describe, and producing a variety of 

 areolets of different size and shape, but generally larger than those of the 

 female : particularly towards the extremity of the elytrum you may 

 observe a space nearly circular, surrounded by one nervure, and divided 

 into two areolets by another.^ The friction of the nervures of the upper 

 or convex surface of the base of the left hand elytrum — which is the 

 undermost — against those of the lower or concave surface of the base of 

 the right hand — which is the uppermost one ; will communicate vibra- 

 tions to the areas of membrane, more or less intense in proportion to the 

 rapidity of the friction, and thus produce the sound for which these 

 creatures are noted ; which, however, according to INI. Goureau, in his 

 elaborate essay on the stridulation of insects, is chiefly owing to the cir- 

 cumstance of one of the strong nervures called by him the how {Varche.t^ 

 being striated or cut transversely like a file, whence it has a much more 

 powerful action on another collection of nervures which he calls the treble- 

 string (la chanfcrcllc).* 



The merry inhabitant of our dwellings, the house-cricket (Gryllxis 



' Sparrman, Voy. i. 312. * Charpenlier in Silbermanu's Revue Entom. iii. 314. 



3 Compare De Gecr, iii. 512. * Ann. Soc. Ent. de France, and Entom. Mag. v. 94. 



