6 THE HOUSE FLY DISEASE CARRIER 



LIFE HISTORY 



A long experience with the study of insects has in- 

 dicated the somewhat remarkable fact that it is about 

 the commonest things in general that we know the 

 least. When Mr. C. L. Marlatt and the writer began 

 in 1895 to work on the subject of household insects, 

 we discovered that very few of the species found so 

 abundantly in households were included in the museum 

 collections. There would be a large series of a rare 

 beetle from Brazil, but no specimens of the common 

 house cockroach, for example ; and when we began to 

 look into the literature of their life histories we learned 

 that published accounts of their transformations were 

 even more scarce than the specimens in the collections. 

 Doctor Hewitt (1910) calls attention to the vision of 

 Sir James Crichton Browne of the aged person show- 

 ing the wondering child the only existing specimen of 

 the house fly, in the British Museum. This was in- 

 tended as a prophecy, but it would not be surprising 

 if before the recent house fly crusade began there 

 really was only one specimen of the house fly in the 

 British Museum. 



With this condition of affairs existing in general, 

 it is perhaps not so surprising that an exhaustive study 

 of the conditions which produce house flies in numbers 

 has really never been made. The life history of the 

 insect was, down to 1873, mentioned in only a few old 

 European works and one more modern one (Taschen- 



