joC TJie Descent of Man. Paui U. 



apparently serves both sexes as a mutual call. Beetles stridu- 

 late under various emotions, in the same manner as birds use 

 their voices for many purposes besides singing to their mates. 

 The great Chias-ognathus stridulates in anger or defiance ; many 

 species do the same from distress or fear, if held so that they 

 cannot escape; by striking the hollow stems of trees in the 

 Canary Islands, Messrs. AVollaston and Crotch were able to 

 discover the presence of beetles belonging to the genus Acalles 

 by their stridulation. Lastly, the male Ateuchns stridulates to 

 encourage the female in her work, and from distress when she 

 is removed .'° Some naturalists believe that beetles make this 

 noise to frighten away their enemies ; but I cannot think that 

 a quadruped or bird, able to devour a large beetle, would 

 be frightened by so slight a sound. The belief that the stridu- 

 lation serves as a sexual call is supported by the fact that death- 

 ticks {Aiiobium tessellatum) are well known to answer each 

 other's ticking, and, as I have myself observed, a tapping noise 

 artificially made Mr. Doubleday also informs me that he 

 has sometimes observed a female ticking,** and in an hour or 

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

 occasion surrounded by several males. Finally, it is 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 hard parts of their 

 bodies; and that as those males or females which made the 

 greatest noise succeeded best in finding partners, rugosities on 

 various parts of their bodies were gradually developed by means 

 of sexual selection into true stridulating organs. 



" M. P. de la Brulcrie, as quoted Landois, ' Zeitschrift fiir wissen. 



in 'Journal of Travel,' A. Murray, Zoolog.' B. xvii. d. 131. Oliver 



vol. i. 1868, p. 135. says (as quoted by Kirby and 



•" According to Mr. Doubleday, Spence, ' lotroduct.' vol. ii. p. 395) 



" the noise is prodnced by the in- tliat the female of Pimelia striata 



" sect raising itself on its legs as produces a rather loud sound by 



" high as it can, and then striljing striking her abdomen against any 



" its thorax five or six times, in hard substance, " and that the male, 



" rapid succession, agai-.st the sub- " obedient to this call, soon attends 



" stance upon which it is sitting." " her, and they pair."' 

 For references on thi.'s raoject see 



