Chap. X. 
COLEOPTERA. 
385 
myself observed, a tapping noise artificially made ; and 
Mr. Doubelday informs me that he has twice or thrice 
observed a female ticking , 75 and in the course of an hour 
or two has found her united with a male, and on one 
occasion 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 suc- 
ceeded best in finding partners, the rugosities on various 
parts of their bodies were gradually developed by means 
of sexual selection into true stridulating organs. 
75 Mr. Doubleday informs me that “ the noise is produced by the 
u insect 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 
u upon which it is sitting.” For references on this subject see Landois, 
1 Zeitschrift fur wissen. Zoolog.’ B. xvii. s. 131. Olivier says (as quoted 
by Kirby and Spence, 1 Introduct.’ vol. ii. p. 395) that the female of 
Pimelia striata produces a rather loud sound by striking her abdomen 
ngainst any hard substance, “ and that the male, obedient to this call, 
soon attends her and they pair ” 
2 c 
VOL. I. 
