176 THE ENTOMOLOGIST. 



The power of stridulation, so marked a characteristic of 

 certain groups of Dermaptera, and present indeed in most if not 

 all insect orders, occurs also in many Hemiptera, and apparently 

 in all or most waterbugs. The phenomenon, however, still 

 requires considerable investigation. 



Stridulation, or the making of certain " musical " sounds, is 

 a term that should apparently be restricted to sounds resultant 

 from two mutually developed interacting surfaces, one of which 

 is the recipient and is usually striated, the other the acting 

 agent and sometimes striated, sometimes consisting of a series 

 of more or less isolated spines or pegs. It may be taken for 

 granted that there must always be tivo specially developed parts 

 of the stridulatory organ, and that these must be interacting 

 and mutually developed. A violin with its bow is a good ex- 

 ample (from an insect point of view) of stridulatory apparatus. 



The first to call attention to the phenomenon in waterbugs 

 was J. L. Frisch,* who remarks that this species produces with 

 its neck a fiddling noise like the Longicorn beetles. Swinton,t 

 a century and a half later, described the results of his investiga- 

 tions, and declared that he had detected minute /-shaped linire, 

 thickly set with strire, on the antero-lateral angles of the meso- 

 notum. Handlirsch \ reinvestigated the whole subject four or 

 five years ago, and ridiculed Swinton, calling the imaginary linme 

 a " Swintonophone." At the same time, however, Handlirsch 

 discovered on the sixth and seventh abdominal tergites of the 

 male numerous transverse striatums which are not present in 

 the female. If these are part of a stridulatory apparatus, the 

 other portion and also the modus operandi remain as obscure as 

 in the case of the Corixid strigil, presently to be discussed. 



It is usually stated that no openings have yet been discovered 

 to the stink-glands in aquatic Hemiptera, the odour appearing 

 in these insects to be connected with the anal parts. 



In Ilyocoris this is distinctly tart, and I have discovered a 

 minute single opening (between the posterior coxse), to which I 

 will recur later on.§ 



Naucoris maculata, Fabricius. 



The claim of this common European bug to admission to the 

 British lists rests upon a single specimen in Buchanan White's 

 collection at the Perth Museum, labelled "England." There is 



:;: 1727, " Beschreibung von allerley Insecten in Teutschland," vi. p. 32. 



t 1877, "On Stridulation in the Hemiptera-Heteroptera " (Ent. Mo. 

 Mag. xiv. pp. 29-31, 2 figs. ; and 1880, " Insect Variety," pp. 108 and 

 203). 



I 1900, " Neue Beitriige zur Kenntniss der Stridulationsorgane boi den 

 Bhynchoten " (Verb.. Zool. bot. Ges. Wien, 1. pp. 555-60, figs. 1-7). 



§ Leidy (1847, J. Ac. Sci. Philadelphia, n. s. i. G4, mentions a similar 

 opening in the Belostomatidse. 



