34 THE HOUSE FLY DISEASE CARRIER 



points out that small flies are found at the end of sum- 

 mer when it has become cooler, and also in the early 

 spring, the latter having hatched late the previous au- 

 tumn. The question of the hibernation of flies will be 

 considered in a later paragraph, but in this connection it 

 should be stated that Doctor Griffith secured repro- 

 duction in the late autumn and winter, but that all of 

 the resulting flies were of small size, though their lar- 

 vae were kept at a warm temperature. The flies from 

 only one of these batches were of normal size, while 

 those in one set were "extremely small, quite pigmies ; 

 and these died from no Apparent cause, probably from 

 marasmus, after a month." He further states that 

 from the same batch of eggs he has reared large, me- 

 dium and small flies. Packard ( 1874) found that those 

 larvae which were reared in too dry manure were 

 nearly one-half smaller than those taken from the ma- 

 nure heap. No direct warmth and the absence of mois- 

 ture seemed to cause them to become dwarfed. 



The error of deduction made by the famous astron- 

 omer was by no means an error of observation, as ap- 

 pears from what precedes, but there are found in houses 

 other flies of entirely different species from the house 

 fly, as will be shown in another chapter. Some of 

 these are considerably smaller, and one of them, the 

 little fly often seen on window-panes (Homalomvui 

 canicularis), is very much smaller. In fact, as though 

 to perpetuate the error, the Germans call this last spe- 

 cies "die kleine Stubenfliege" the little room fly or 

 house fly. 



