THE CANADIAN ENTOMOLOGiST. 341 



This bug was reduced by Mayr to synonymy, and evidently he 

 did not consider it more than a local variety. In fact, he says so 

 in so many words (op. c, p. 430). The species, however, is well marked. 

 Stai recorded it from Madagascar originally, and it does not appear to 

 have been mentioned since. I possess a specimen from that Island. It is 

 apparently restricted to that territory. 



III. — Diplonychus rectus^ Mayr. 

 Hydrocyrius rectus. 



1863. — Mayr, Verb Zool.-bot. Ges. Wien, p. 359. 

 1864. — Signoret, An. Soc. Ent., Fr. (4), IV, 224. 

 1871. — Mayr, Die Belostomiden Verb Zool.-bot. Ges. Wien, 

 XXI, 430. 

 No other records are to be had of this well-defined species than that 

 of the author, who gives Sierra Leone (West Africa) as its habitat. It is 

 10 mm. shorter \.\\a.n piinctatus, Stal, from which the character given in the 

 table at once separates it. 



In conclusion, I wish to express my thanks to Mr. G. W. Kirkaldy, 

 whose independent investigation when I called his attention to the generic 

 emendation proposed, confirmed the conclusion I had already reached. 

 He added in his letter other important synonymical matter, which it is to 

 be hoped he will make public ere long. 



PRACTICAL AND POPULAR ENTOMOLOGY.— No. 23. 



Fumigation with Hydrocyanic Acid Gas kor Bedbugs. 



by glenn \v. herrick, agricultural college, miss. 



Futnigatioti of a Large Building. 



For the past two years we have used hydrocyanic acid gas on an 



extensive scale with considerable success, and thinking that the experience 



gained might be of benefit to other workers who may be confronted with 



the same problem it seemed worth while to give an account of the work 



and method of procedure. 



Our dormitory building, in which the work has been done, is a large 

 4-story structure in the form of an E, and contains, all told, 253 rooms of 

 different sizes on the different floors. We use approximately the formula 

 recommended by Dr. L. O. Howard in Circular 46, s.s., the only change 



Qctober, 1907 



