33 



The Stridulattng Orgaks of Waterbugs (RiiYNCHOxy ), 



especially of corixidae. 



By G. W. Kirkaldy, F.E.S. 



Communicated hy D, J. Scourfieldy F.R.M.S. 



(Bead January IStJi, 1901.) 



Plates 3 and 4. 



It has been known for many years that certain waterbugs possess 

 the power of stridulating, that is to say, of making musical sounds 

 through the interaction of specially developed portions of their 

 chitinous integument. 



The first notice of which I am aware, is that of Frisch (1) who, 

 in 1740, noted that the common European broad waterbug 

 {IlyoGoris cimicoides) produces a fiddling sound with its neck. In 

 1846 Robert Ball (2) recorded the fact that Corixa striata Curtis 

 emitted a powerful sound, so loud as to be distinctly audible in an 

 adjoining room through the closed door. These sounds, which 

 w^ere somewhat like those of a cricket, were given out while the 

 insect was about two inches and a half under water. The obser- 

 vations were due, in the first place, to Miss M. Ball, in 1840, and 

 were afterwards repeatedly verified by herself and Mr. Ball. It 

 was also noted that the sounds were probably made by the male 

 only. This incomplete discovery was recorded in the Bevue 

 Zoologique in 1846 (3), and somewhat amplified in the same year 

 by Mr. Ball (4). In the last paper the following points were 

 noticed : viz., the Corixa anchored itself by means of the middle 

 pair of legs ; " it then moved the fore-legs rapidly in front of its 

 head and gave three brisk little chirps ; very often after the 

 chirps it made a noise something like grinding a knife, only very 

 much fainter and softer ; while doing so it moved its body rapidly 

 from side to side, still keeping the hind legs stretched out." The 

 sound may be heard at any time, but is very uncertain ; the 



JouRN. Q. M. C, Series II.— No. 48. 3 - 



