400 THE DESCENT OF MAN 



hardly be a doubt that the males stridulate in order to 

 call or to excite the females; but with most beetles the 

 stridulation apparently serves both sexes as a mutual call. 

 Beetles stridulate under various emotions, in the same man- 

 ner as birds use their voices for many purposes besides sing- 

 ing to their mates. The great Chiasognathus 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. Wol- 

 laston and Crotch were able to discover the presence of 

 beetles belonging to the genus Acalles by their stridula- 

 tion. Lastly, the male Ateuchus stridulates to encourage 

 -the female in her work, and from distress when she is re- 

 moved." 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 stridulation serves as a sexual call is supported by the 

 fact that death-tick-s {Anohium tessellatum) are well known to 

 answer each other's ticking, and, as I have myself observed, 

 a tapping noise artificially made. Mr. Doubleday also in- 

 forms me that he has sometimes observed a female ticking,'" 

 and in an hour or two afterward he 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 



" M. P. de laBrulerie, as quoted in "Journal of Travel," A. Murray, vol. i., 

 1868, p. 135. 



8° According to Mr. Doubleday, "the noise is produced by the insect raising 

 ;tself 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 refer- 

 ences on this subject see Landois, "Zeitschrift fiir Wissen. Zoolog.," B. ivii. s. 

 131. Oliver says (as quoted by Kirby and Spence, "Introduot.," vol. ii. p. 

 393) that the female of Pimelia striata produces a rather loud sound by striliing 

 her abdomen against any hard substance, "and that the male, obedient to this 

 call, soon attends her, and they pair." 



