Chap. X.j COLEOPTERA. 273 



noise to frighten away their enemies ; but I cannot think 

 that the quadrupeds and birds which are able to devour 

 the larger beetles, with their extremely hard coats, would 

 be frightened by so slight a grating sound. The belief 

 that the stridulation serves as a sexual call is supported 

 by the fact that death-ticks (Anobiwn tessellatum) are well 

 known to answer each other's ticking, or, as I have my- 

 self observed, a tapping noise artificially made ; and Mr. 

 Doubleday informs me that he has twice or thrice ob- 

 served a female ticking, 76 and in the course of an hour or 

 two has found her united with a male, and on one occa- 

 sion surrounded by several males. Finally, it seems 

 probable that the two sexes of many kinds of beetles were 

 .at first enabled to find each other by the slight shuffling 

 noise produced by the rubbing together of the adjoining 

 parts of their hard bodies ; and that as the males or 

 females which made the greatest noise succeeded best in 

 finding partners, the rugosities on various parts of their 

 bodies were gradually developed by means of sexual se- 

 lection into true stridulating organs. 



75 Mr. Doubleday informs me that " the noise is produced by the in- 

 sect raising itself on its legs as high as it can, and then striking its thorax 

 five or six times, in rapid succession, against the substance upon which 

 it is sitting." For references on this subject see Landois, ' Zeitschrift 

 fur wissen. Zoolog.' B. xvii. s. 131. Olivier says (as quoted by Kirby and 

 Spence, ' Introduct.' vol. ii. p. 395) that the female of Fimelia striata 

 produces a rather loud sound by striking her abdomen against any hard 

 substance, " and that the male, obedient to this call, soon attends her, 

 and they pair." 



