W. R. G. Atkins 217 



ethyl alcohol. Beer, however, was much better as a lure, and it was also 

 noticed that the addition of a little Egyptian made alcohol was very 

 effective. Dishes containing about 1 per cent, formalin and a little of 

 this crude alcohol compassed the death of many thousands of flies in 

 our camp. Doubtless the amyl alcohol, of which, together with the other 

 fusel oil constituents there appeared to be a noticeable amount in this 

 product, attracted the flies, and some traces of esters of these alcohols 

 may also have been present. 



Speyer has drawn attention to the attraction that iso-amyl acetate 

 and other esters of these alcohols have for flies. There is no doubt that 

 it is very powerful, for our "doping" sheds were usually infested with 

 flies even when neighbouring sheds or hangars were comparatively free 

 from them. Now aeroplane "dope" consists of acetyl cellulose dissolved 

 in a mixture containing acetone, methyl-acetate, methyl alcohol, ethyl 

 alcohol and benzene as solvents or diluents and benzyl alcohol as a 

 residual solvent to keep the film pliable. Though neither benzene, acetone, 

 methyl nor ethyl alcohol attract flies in any noticeable manner, the 

 methyl acetate may have a decided positive effect, and it is just possible 

 that benzyl alcohol may also, but this is rather unlikely, as shown by 

 Speyer. 



Far greater however than the attraction of dope was that exerted 

 by the nitro-cellulose varnish, in which the main solvent was iso-amyl 

 acetate at first, and later on >i-butyl acetate, the w-butyl alcohol having 

 become available as a result of the preparation of acetone by a bacterial 

 process. The thousands of flies attracted from a neighbouring village by 

 the strong odoui" of butyl acetate afforded an example of chemotropism 

 on a very large scale. 



The considerable supplies of w-butyl alcohol produced in the prepara- 

 tion of acetone by the fermentation method have resulted in this alcohol 

 becoming available in surplus, so its utilization in quantity as the acetate 

 in a campaign against flies ought to be possible. The ester is volatile, 

 and boils at 125° C, so it would have to be replenished at intervals. Iso- 

 amyl acetate is sUghtly less volatile and boils at 139° C. 



LITERATURE CITED. 



Imms, a. D., and Husain, M. A. (1920). Field experiments on the chemotropic 



responses of insects. Ann. App. Biol, vi, 269-92. 

 Morrill, A. W. (1914). Experiments with house-fly baits and poisons. Jouni. 



Ecoii. Entom. vn., 2(38-74. 

 Speyer, E. R. (1920). Notes on the chemotropism of the house-fly. Ann. App. 



Biol. VII, 124-40. 



{Received April Uh, 1921.) 



