

THE ENTOMOLOGIST. 



Vol. LI.] JUNE, 1918. [No. 661 



THE DEATH-WATCH: NOTES AND OBSEKVATIONS. 

 By C. J. Gahan, M.A., D.Sc. 



Thkre are two kinds of "death-watch," and more than two 

 centuries have j^assed since that fact was well established and 

 first made known. But for some reason, not easy to explain, 

 Derham's interesting observations on the " death-watch " had 

 been strangly neglected by entomological writers until Dr. Sharp 

 called attention to them in the Cambridge Natural History. Like 

 many other entomologists at the time, I was myself altogether 

 unacquainted with them, when about sixteen or seventeen years 

 ago I first heard the ticking of the book-louse, and it was not 

 until I had traced the ticking to its source that I came to know 

 that the little insect known under that name was able to make a 

 noise of the kind. 



There is now little excuse for entomologists in this country 

 to remain either ignorant or incredulous of the fact that the 

 book-louse is a genuine death-watch, and beats at a slower rate 

 and for a much longer time in succession than does the other 

 death-watch, which " beateth only about seven or eight strokes at 

 a time, and quicker." The fact, however, appears to be little 

 known yet amongst continential writers. 



In a valuable and very interesting paper on the Anobiid 

 beetles which appeared less than three years ago, the Swedish 

 author. Mr. N. A. Kemner, who was treating of them chiefly 

 from the economic point of view, had occasion to refer to the 

 ticking noise they make, and he referred also to the book-louse 

 in that connection. 



Mr. Kemner tells us that Linn6, who had heard the ticking 

 noise, mistook its origin and attributed it to the little insect called 

 the book-louse, which, for that reason, he named Termes pulsa- 

 torium, but the mistake was soon afterwards corrected by C. A. 

 Schmid, who observed Anohium pertinax in the very act of ticking. 



I have not yet seen what Schmid had to say on the subject, 

 but in reference to Mr. Kemner's statement it is well to point out 

 that Linne made no mistake whatever in the matter, for, so far 

 as I know, he never said that he had heard the ticking either of 



ENTOM. — JUNE, 1918. M 



