R. A. Wardle 9 



according to thickness of thread, is that it absorbs the oil readily, and, 

 owing to its diamond pattern, is fairly elastic. The oil is fairly expensive 

 if purchased from the retail phaimacist, but can be obtained from 

 W. J. Bush et Cie, Grasse, Alpes Maritimes, or from their Hackney 

 branch, at 3s. 9d. per lb. or at a lower price for quantity. The exact 

 specification is Oil Aniseed, China Star. Oil of sweet fennel would be 

 probably just as effective in spite of its lower percentage of anethole, 

 but costs 10s. per lb. A pound of the oil goes a long way, however, if 

 applied in the manner described. 



There would seem little advantage to be gained by diluting with 

 methylated spirits or emulsifying with soap solution. Hasty and inter- 

 rupted experiments seemed to indicate that the efficiency of emulsions 

 of the oil varies directly in proportion to the percentage of oil present. 

 Thus a 50 per cent, emulsion was not effective after twelve hours, a 

 25 per cent, emulsion not effective beyond six hours, and an emulsion 

 containing less than 10 per cent, of oil not reliable at all. However, 

 accurate work is needed to clear up this point. 



LITERATURE. 



(1) Spence, W. (1836). Trans. Ent. Soc. London, i. 



(2) Herms, W. B. (1911). Journ. Exj). Zool. x, p. 167. 



(3) Cooper, W. F. and Walling, W. A. B. (1913). Ann. App. Biol, ii, 2 and 3. 



(4) Lodge, Olive C. (1916). Proc. Zool. Soc. p. 481. 



(5) Mellor, J. M. (1919). Ann. App. Biol, yi, ]. 



{Received February 5fh, 1921.) 



