J. E. M. Mellor 61 



winter at temperatures below 45°-55° F. When fresh manure was not 

 added to the experimental lioap emergence ceased owinj; to the fall of 

 temperature, which had been kept up by fermentation. But he thinks 

 that pupae, which were located near the surface of the soil, received 

 either enoufjh heat for emergence or were probably killed by cold. He 

 found that flies tend to seek a temperature of 60° F., but that, given 

 that they had sufficient food, their only chance of living for any length 

 of time was to remain dormant. He suggests, as the result of a single 

 experiment, that Em/pusa inuscae developes principally in sexually 

 matured and fertilised females, which do not oviposit on account of cold 

 or lack of suitable media. 



Finally Group IV is represented by Skinner (1913), who observed 

 fresh specimens of M. domestica entering his laboratory window on 

 March 13th, 1913, and states that, until disproved, he will answer the 

 question "Do flies hibernate? " thus, "house-flies pass the winter in the 

 pupal stage and in no other way." 



At the suggestion of Dr Graham-Smith, a careful examination of 

 manure heaps and their vicinities and other likely places, for larvae and 

 pupae, was started in January 1916, and was continued during the winter 

 1916-1917. During the summer of 1916 and the early portion of that of 

 1917 various experiments and observations were made, a full account of 

 which will be found in the Cambridge University Library {Research 

 Student's Dissertation, 166). In this paper a short account only is given 

 of observations made on overwintering and summer distribution of flies ; 

 and of three of the experiments, carried out during the summer, to 

 investigate (1) the temperature of horse manure heaps; (2) the effect of 

 applications of Creosote Oil Mixture and the best method to apply it; 

 and (3) to discover whether the burial of material infested by the fly 

 larvae, at a depth of four feet, would prevent the developement or escape 

 of the adult, where the larvae would pupate under these conditions and 

 to what height the adults were capable of climbing in various soils, loose 

 or tightly packed. 



This work was carried out on a grant from the Medical Research 

 Committee and under the direction of Dr G. S. Graham-Smith, to whom 

 my sincere thanks are due for his ever ready help and encouragement 

 throughout the investigation. My thanks are also due to Mr Forman for 

 much help and suggestion in the designing of apparatus in Series 3 (facing 

 pp. 69, Figs. 1, 2, and 70, Figs. 3, 4), and to Mr C. G. Lamb and to 

 Dr KeiHn for their kindly help and sympathy and for identifying certain 

 of the flies caught or bred during the experiments. 



