U"o, 2, ] Notes. 87 



first be made to ascertain to what extent the reduction, which undoubt- 

 edly occurs, in the numbers of the fly at the end of the rains, is due 

 to causes other than the scarcity of silk-worms ; for it is a well-known 

 fact that very many insects in India increase inordinately in numbers 

 during- the rains and die down again naturally with the advent of the 

 cold weather. 



The suffocation by heat to which cocoons intended to yield silk 

 are subjected, in all cases destroys any maggots they may contain. It 

 is obvious, therefore, that the speedy suffocation of all cocoons obtained 

 from fly-blown worms must tend to reduce the evil ; while general 

 cleanliness in the rearing-rooms must also be useful in preventing the 

 accumulation of dust and dirt in which the maggots conceal themselves 

 when about to pupate. 



Cleghorn notices that spiders destroy numbers of the flies, and that 

 a small beetle (probably Dermestes vulpinus), which 

 also attacks silk- worms and chrysalids, will eat the 

 maggot of the fly ; but that the greatest enemy of the fly is a smaller fly. 

 He names this smaller fly " the midge/' and supposes it to be parasitic 

 upon the silk-worm fly. In proof of this he confined twelve fly-blown 

 worms with some midges in a muslin-covered glass with earth at the 

 bottom. The fly-blown worms had a total of twenty-one black marks 

 upon them, each mark showing the presence of a maggot, about four 

 days old, capable of developing into a fly. The worms were carefully 

 tended, but produced only two silk-worm flies, together with over one 

 hundred midges, indicating that the midges had in some way caused 

 the death of the silk-worm flies. 



The midge proves to be a dipterous insect, belonging to the family 

 Muscidse, and is probably a new species. Specimens, obtained by 

 Marshall, of Berhampore, have been sent to Europe for examination; 

 and it is hoped that practical entomologists in the silk districts, where 

 specimens can readily be obtained, will set themselves to elucidate the 

 interesting question of the connection which exists between this insect 

 and the silk-worm fly. It is by no means improbable that the midge 

 may be found to be parasitic upon the maggot of the silk-worm fly, much 

 as the latter is parasitic upon the silk-worm ; and this supposition is 

 supported by Marshall's observation 1 of the deposition of the eg-gs of 

 the midge upon the grub of the silk- worm fly, within a few hours of 

 the latter's cutting its way out of a silk-worm cocoon. 



In order to breed the midge in sufficient numbers to keep down the 

 fly, Marshall suggests that in silk establishments a practice should be 

 made of always putting any maggots that can be found of the silk-worm 

 fly into a close worm basket, with a perforated lid, the perforations 



1 Indian Museum Notes, I (1), p. 63 (1889). 



