PREFACE 



THE dangers of house-flies to the health of the community 

 have come into such recent prominence that the appear- 

 ance of Major Hurlstone Hardy's book should fill a want. 

 It is written lucidly and clearly, yet in that popular style 

 which is so frequently lacking in scientific works. This is 

 a great advantage. Too often scientists are prone to 

 bring out works couched in terms which cannot be under- 

 stood by an interested public that is not versed in technical 

 terms. Thus matter which is of the greatest general 

 importance is passed unread by many, and is, in conse- 

 quence, not acted upon. 



Major Hardy has a knowledge of these deadly insects 

 which, in my opinion, is unsurpassed, because he has the 

 personal experience of practical experiment combined 

 with the instincts of the naturalist. The result is an 

 account both accurate and interesting which should prove 

 of the greatest value. 



The discovery of the transmission of disease by mos- 

 quitoes required the passage of a decade before its essentials 

 were grasped by the public mind ; that of the prevention 

 of small-pox required a century. But the dangers of 

 house-flies is rapidly becoming known in consequence of 

 the popular literature, which is growing, describing the 

 details of the lives of these loathly creatures. In this way 

 only can such knowledge be spread a knowledge which 

 must become general before flies and the maladies they 

 convey can be generally and satisfactorily dealt with. It 

 is of little use to make great discoveries and then to hide 

 them on the musty bookshelves of learned societies. 



