87 



because the habitat of plague-carrying fleas is in the burrows of rodents 

 and on their bodies, and when temporarily separated therefrom, the 

 natural tendency of the fleas is to regain that habitat. Diffusion of 

 infection within a city results chiefly, if not entirely, from migration 

 of infected rodents, and these latter when transported in merchandise 

 are responsible for the spread of infection from one community to 

 another. The reduction of rodents and the prevention of their 

 dispersal should therefore be the chief prophylactic measures. 



AsHwoRTH (J. H.). A Note on the Hibernation of Flies. — Scottish 

 Naturalist, Edinburgh, no. 52, April 1916, pp. 81-84. 

 The following flies were collected in a house in Edinburgh on 22nd 

 February 1916 : — Limnophora septemnotata, Zett., Pyrellia erioph- 

 thalma, Macq., Muscina stabulans, FaU., CallipJiora {Protocalliphora) 

 groenlandica, Zett., Pollenia riidis, F. The great majority of the 

 specimens were L. septemnotata, while all were females except two 

 examples of M. stabulans. A second inspection on 7th March resulted 

 in the capture of large numbers of L. septemnotata and one specimen 

 each of M. stabulans and C. groenlandica, all the specimens being 

 females. L. septemnotata was very abundant during the past autumn 

 and to a less extent during previous years. The rooms with a southern 

 aspect were invaded during September and October and hibernation 

 in various sheltered crevices began during November. The activity 

 of the females was resumed on the return of favourable conditions. 



WiDMANN (E.). Beitrage zur Kenntnis der Biologic der Kleiderlaus 



und deren Bekampfung. [The biology of clothes lice and their 



control.] — Bull. Inst. Pasteur, Paris, xiv, no. 6, 30th March 



1916, p. 190, [Abstract from Zeitschr. f. Hygiene, Ixxx, 1915, 



p. 289.] 



Development of the eggs of lice requires from six to seven days at a 



temperature of 78° to 85° Fahr. The optimum temperature is 82° Fahr. 



Development is retarded when the temperature is raised from 94° to 



113° Fahr., as it also is at low temperatures from 68° Fahr. down to 



13° Fahr. At 122° Fahr. the eggs are killed in 15 minutes, at 139° Fahr. 



in five minutes. The most efficient destructive agents are heat, then 



sulphurous anhydride and carbon bisulphide. These last ensure 



death of the eggs in 15 minutes. Tables are given showing the action 



of these various insecticides. 



Heymann (B.). Die Bekampfung der Kleiderlause. [Combating 

 clothes lice.] — Bull. Inst. Pasteur, Paris, xiv, no. 6, 30th Marct 

 1916, p. 191. [Abstract from Zeitschr. f. Hygiene, Ixxx, 1915 

 p. 299.] 

 After deahng with the morphology and biology of Pediculus humanus 

 {vestimenti), methods of destruction are discussed. Lice are killed in 

 three hours at a temperature of 113° F., in 1| hours at 122° F., in 

 20-30 minutes at 140° F., and in 5-10 minutes at 177° F. The eggs 

 require a Httle longer time. In practice, heating for one hour at 140° F. 

 should be sufficient. At a low temperature, 50-55° F., lice may be 

 kept fasting for nine days, while at the temperature of garments 

 (77-80° F.) they only live from three to five days without food. The 

 -action of various chemical agents is also dealt with. 



(C269) a2 



