396 NOISES OF INSECTS. 



one, which covers the back. In the female both these 

 portions resemble each other in their nervures; which 

 running obliquely in Uvo directions, by their intersec- 

 tion form numerous small lozenge-shaped or rhom- 

 boidal meshes or areolets. The elytra also of these have 

 no elevation at their base. In the males the vertical 

 portion does not materially difl'er from that of the fe- 

 males ; but in the horizontal the base of ea<:h elytrum 

 is elevated so as to fomi a cavity underfieath. The 

 nervures also, which are stronger and more prominent, 

 run here and there very irregularly with various in- 

 flexions, describing curves, spirals, and other figures 

 difficult and tedious to describe, and producing a vari- 

 ety of areofets of different size and shape, but generally 

 larger than those of the female : particularly towards 

 the extremity of the wing you may observe a space 

 nearly circular, surrounded by one nervure, and di- 

 vided into two areolets by another''. The friction of 

 ihe nervures of the upper or convex surface of the base 

 of tlie left-hand elytrum — which is the undermost — 

 against tliose of the lower or concave $urfa<;e of the base 

 of the right-hand — which is the uppermost one — will 

 communicate vibrations to the areas of membrane, more 

 or less intense in proportion to the rapidity of the fric- 

 tion, and thus produce the sound for which these crea- 

 tures are noted. 



The merry inhabitant of our dwellings, .the house- 

 cricket (Aclieta domestica, F.), though it is often heard 

 by day, is most noisy in the night. As soon as it grows 

 dusk, their shrill note increases till it becomes quite aE 

 annoyance, and interrupts conversation. When the 



* Compare De Geer, iii. 512. 



