LIFE-HISTORY 45 



and sacking, which are fouled with excremental products, if they 

 are kept moist and at a suitable temperature. They were also 

 reared on decaying vegetables thrown away as kitchen refuse, 

 and on such fruits as bananas, apricots, cherries, plums and 

 peaches, which were mixed, when in a rotting condition with 

 earth to make a solid mass." 



In India the breeding of M. doviestica and allied species in 

 large numbers in night soil has been noticed by numerous 

 observers. 



During their whole lives the larvae shun the light, but 

 according to the experiments of Felt (1910, p. 34), although 

 flies crawl into dark crevices of manure to lay their eggs, they 

 will not lay them freely in dark places. 



The larvae " thrive and m.ature most rapidly, and are always 

 most abundant in fermenting materials ; but they can also 

 mature in non-fermenting substances during warm weather, 

 though under such conditions they do so very slowly. In stable 

 manure they are generally most numerous a few inches below 

 the surface, and undoubtedly work their way upwards day by day 

 into the fresh material a few hours (five or six) after it has been 

 added to the previous accumulation. This marked habit is 

 evidently due to the excessive heat which is engendered in the 

 lower strata of the manure." 



" Under the most favourable conditions as to temperature 

 and food supply they mature in five to eight days ; but when 

 fermentation does not take place, this stage, even in hot weather, 

 may be prolonged to several weeks (six to eight)." 



" In midden steads the fully matured larvje crawl away to the 

 sides or to the top of the wall or framework of the receptacle ; in 

 ash-pits they locate themselves in various materials as well as 

 ashes, but are evidently partial to old bedding, paper, rags, 

 usually in or near the centre of fermentation " (Newstead, p. 15). 



In any case the larva leaves, if possible, the more or less 

 moist situation and crawls away sometimes several yards in 

 search of some dry and sheltered spot. 



After a short resting stage during which the alimentary canal 

 is emptied of organic matter pupation occurs. 



At the beginning of this change the body contracts by the 



