320 



exposure for 10 minutes to an atmosphere containing a few centi- 

 grammes of volatile liquid per litre causing death ; benzyl bromide at a 

 strength of a few centigrammes a litre causes a passing excitement and 

 lively contortions, from the point of view of toxicity coming between 

 carbon bisulphide and monochloracetone ; chlorpicrin is still more 

 active than monochloracetone, a few milligrammes per litre being 

 sufficient to cause death sooner or later ; hydrocyanic acid in slight 

 concentrations causes an anaesthesia or complete paralysis resembling 

 death, but after a time the larvae revive and slowly recover their 

 functions, doses larger than those of chlorpicrin being necessary to 

 cause death. 



There does not seem to be any difference in the toxicity of these 

 substances for the other species experimented upon, the outstanding 

 fact being the great insecticidal value of chlorpicrin, which is at least 

 equal in practice to that of hydrocyanic acid. 



VuiLi.ET (A.). Note sur Picromerus bidcns, L., H6miptere pr6dateur 

 des Larves de Chrysomelides.— 5'<Z^. Soc. Entom. France, Paris, 

 1919, no. 6, 26th March 1919, pp. 118-119. [Received 28th May 

 1919.] 



The bug, Picromerus bidens, L. , has been observed to be predaceous 

 on the larvae of Melasoma populi, L., and M. tremulae, ¥., infesting 

 young poplars in the department of Seine-et-Oise in October 1918 ; 

 dead larvae were only attacked in the absence of living ones. 



Williamson (W.). Some Insect Enemies of Corn. — Minnesota Agric. 

 Exten. Div., Univ. Farm, St. Paul, Spec. Bull. no. 8, July 1916, 

 14 pp., 11 figs. [Received 28th May 1919.] 



This popular bulletin describes the commoner insect pests of maize 

 and gives the usual remedial measures. 



EuGGLES (A. G.) The White-marked Tussock Moth.— Office of State 

 Entomologist, St. Paul, Minn., Ciic. no. 42, 5th April 1917, 4 pp., 3 

 figs. [Received 28th May 1919.] 



A short life-history of the well-known shade-tree pest, Hemerocampa 

 leucostigma, S. & A., is given, with particulars of remedial measures 

 [see this Review, Ser. A. v. p. 174, and vi, p. 330, etc.]. 



Washburn (F. L.). The Hydrocyanic Acid Gas Treatment for the 

 Flour Moth. — Office of State Entomologist, St. Paul, Minn. Circ. 

 no. 46, 15th January 1918, 13 pp.,'l plate, 4 figs. [Received 

 28th May 1919.] 



This circular, which is a reprint of an earlier one, gives detailed 

 instruction for the fumigation of flour mills with hydrocyanic acid gas 

 as a remedy for infestation with Ephestia kuhniella (Mediterranean 

 flour moth). It is considered that control by heating, when all parts 

 of the mill are maintained at a temperature of from 123° to 125° F. for 

 several hours, is preferable to any other method when feasible. 



