" 



142 OLIVE C. LODGE. 



Fannia canicularis (lesser house-fly), Fannia scalaris (latrine fly), Calliphora 

 erythrocephala (blue-bottle), Calliphora vomitoria (blue-bottle), Lucilia caesar 

 (green-bottle), and Phormi azurea (groenlandica). 



The blow-flies were obtained for the most part from those caught in traps set in 

 the Zoological Gardens. They were also bred for a time in a greenhouse at the 

 Imperial College, when beef and mutton scraps were used as the principal food both 

 for flies and maggots. The best results were obtained, both with the maggots and 

 flies, when the air in the greenhouse, which became very hot, was kept moist ; 

 if this was not done, they — and more particularly the flies — very soon died. 



The supply of house-flies was kept up by breeding from the descendants of the 

 flies which emerged from pupae collected from a manure-heap near London, in July 

 1915. Breeding was carried out in the fly room (Plate VIII) and in the same way 

 as formerly, viz., by using mixtures of casein, bread, water and banana, surrounded 

 by a layer of dry rubbish in which the maggots could pupate, the whole being placed 

 in very large saucers (Plate IX, fig. 1). It was thus possible to keep up a 

 continuous supply of flies during 14 months. House-flies were found to be hardier 

 and easier to breed than blow- flies. 



Fannia were also bred in the same mixtures, and under the same conditions and 

 for the same period of time as Musca ; although they never bred in such large numbers 

 as the latter. 



In all experiments the different substances were as far as possible tested on 

 free flies, and also on those confined in glass cylinders (8 in. X 9 in.) with muslin 

 tops. 



When flies were needed for the cylinders, they were generally caught in balloon 

 traps placed over the breeding saucers. In all cases controls were set up for each 

 series of experiments. It was thus possible to compare the behaviour of the flies 

 under different conditions, and to obtain an idea of the relative value of tbe different 

 substances tested. 



Experiments to test the liees and dislikes of flies. 



Foods— baits, deterrents and poisons. 



A certain number of experiments of a more or less preliminary nature were made, 

 in order to compare the proportion in which the sexes came to feed, and to find the 

 most suitable medium to employ as a foundation to which the various chemicals, 

 colours, etc., could be added. During the experiments the substances were watched 

 and the numbers of flies feeding counted at intervals during the day. 



The results showed that on the whole the sexes came to the baits in approximately 

 equal numbers.* More females, however, were noticed at foods containing a few 

 drops of ammonia ; although when ammonia, or ammonia and water, were exposed 

 alone, this was apparently not the case. When casein and honey baits were exposed, 

 more females generally came to the former. Again larger numbers of females were 

 always seen frequenting the breeding saucers, containing mixtures of casein, bread, 

 water and banana. This was however to be expected, and confirms the. results 

 obtained by Gordon Hewitt for wild flies and those found in houses.f 



* The sexes emerged in approximately equal numbers, 

 f C. Gordon Hewitt, " The House-Fly." 



