114 DIPTERA. 



The Blue-bottle (J/, vomitoria), so troublesome to 

 housekeepers, more especially in liot sultry weather, 

 by depositing its eggs (fly-blows) upon the joints 

 of meat designed for the table, developes its pupae in 

 the same manner as does the domestic house-fly. The 

 flesh-fly (Sarcophaga), with thorax and abdomen marked 

 with rows of white stripes and spots, is viviparous in its 

 mode of reproduction ; the eggs, which are developed 

 within the body of the parent, are very large ; they 

 are arranged in a spiral form, resembling two white 

 rows of ribbon. Rdaumur calculated that one fly 

 would produce 20,000 maggots ; it was this species 

 to which Linneus referred when he said that these 

 flies could eat an ox as fast as a lion could ! These 

 all belong to the division of Calytera. 



The remaining fly {Scatophaga stercoraria), the 

 Covv-dung-fly, belongs to the second division. Let no 

 one despise this bright, active, yellow insect, which acts 

 as a useful scavenger in removing offensive matter. 

 Your approaching footsteps drives the living cluster all 

 of a sudden away "with mighty buzz and bustle," 

 quickly however to return on your departure from the 

 spot. The eggs of the Cow-dung-fly are deposited on 

 the dung on which the larvae feed. Reaumur found 

 that the eggs required to be immersed in the moist 

 dung; that if they were not thus surrounded with mois- 

 ture they shrivelled up and came to nothing ; it was 

 equally necessary that the eggs should not be wholly 

 covered, otherwise the young larvse would be suffocated 

 at their first exit from the Qgg. In what way is this 

 nice point secured ? In this manner. Each Qgg is pro- 

 vided, near its upper end, at which the animal when 



