173 



A GUIDE TO THE STUDY OF BRITISH WATERBUGS 

 (AQUATIC RHYNCHOTA). 



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



(Plate II.) 



(Continued from vol. xxxiii. p. 152.) 



Since publishing the last instalment of this "Guide," Mr. 

 Halbert informs me that a dead Aphelocheirus was taken by 

 Mr. Buckle from Loch Neagh in Ireland. I presume this was 

 recorded in the ' Irish Naturalist ' at the time, but I have un- 

 fortunately no access to this journal. 



Ilyocoris cimicoides (Linne). 



In Ilyocoris the same general appearance obtains as in 

 Aphelocheirus, but the dorsal part of the head is bent under in 

 front, the antenna shortened and thickened, the anterior femora 

 greatly thickened, and the posterior tibiae and tarsi somewhat 

 modified for natatory purposes. 



The rostrum is considerably shortened, not extending beyond 

 the anterior coxaa. The antennas are composed of four segments, 

 and do not reach, when extended, beyond the lateral margins o*f 

 the head ; the head is excavated [viewed from below] beneath 

 the apical segments of the antenna?, forming what is probably an 

 auditory chamber for the intensifying of sounds.* 



The anterior femora are greatly thickened, as mentioned 

 above, but are not suddenly ampliated in a right angle at the 

 base beneath and then narrowed. Also internally beneath there 

 is a broad pad of hair the whole length (fig. 45). 



There is only one British species, /. cimicoides (Linn.) ; the 

 head, pronotum, scutellum, connexivum, legs, under side, &c, 

 are pale greenish testaceous ; the head, pronotum, &c, irregu- 

 larly punctured with brown. The intermediate and posterior 

 legs are well furnished with brown spines. The elytra dark 

 greyish brown, very closely and finely punctured. Abdomen 

 black above. 



It is excellently figured by Douglas and Scott, and also very 

 well by the old author A. J. Rosel von Rosenhof ('Der Monatlich- 



* I have noted in the 'Entomologist' (xxxii. p. 114) that Microvelia 

 pygmcea does not use the antenna} as tactile organs. Newport ("On the Use 

 of the Antennae in Insects," 1840, Trans. Ent. Soc. Loud. ii. p. 235), how- 

 ever, considers that the antennae in water cirnices (i. e. Ilyocoris) and Noto- 

 necta are auditory, sometimes also tactile, certainly not smell organs. They 

 are of great though not of vital importance. He frequently observed the 

 above-named bugs sticking to the sides, and lying beneath the wall of an 

 outhouse that Lad recently been covered with coal-tar, which emits an odour 

 of carburetted hydrogen, the gas that is so abundantly formed in stagnant 

 pools. 



