NOTE. Fig. 4 has been found to be not available for this edition. ------------------------------------------------------------------------ PREFACE The dangers of house-flies to the health of the community have come into such recent prominence that the appearance 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 understood 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 consequence, 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 mosquitoes 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. Instead, they should be adapted to practical purposes applied for the good of suffering humanity; and the best way to do this is to bring out well-written, interesting, and easily read books of this kind, so that all who run may read and their readings endure. This book should assist much to accomplish this end. Thus we may look forward confidently to the day when house-flies, and the diseases they carry, are things of the past. The "Book of the Fly" must take its place in the history of the events which are to lead up to the winning of that goal. HALFORD ROSS (_of the John Howard McFadden Researches at the_ _Lister Institute of Preventive Medicine_). ------------------------------------------------------------------------ THE BOOK OF THE FLY CHAPTER I THE HOUSE-FLY, A PRODUCT OF HUMAN INSANITATION With the present day zeal for popularising interest in common things (called nature study) there has arisen the demand for knowledge practically useful and thoroughly up-to-date, yet in a form free from much of the technical terminology and treatment which are essential in the student's more fully developed scientific handbook. The "House-fly" is a fit subject for a simplified study of this kind, and the present booklet is an attempt to afford information very different to that of the "popular" works, which only were accessible to the writer's hands between fifty and sixty years ago; the writers of those old books all followed the lead of the reverend and learned contributors to the famous and monumental "Bridgwater Treatises." "The Wonders of Nature explained," "Humble Creatures" (a study of the earth-worm and the house-fly, in popularised language), "The Treasury of Knowledge," "Simple Lessons for Home Use," were the kind of cheaper works in touch with a past generation; these latter and other later well-intended publications will now be found to be somewhat deficient or even a little misleading entomologically; they abounded in pious sentimentality and mostly attempted an aggravatingly grandiose literary style, but all have rather failed...