SCPvEENING OF HOUSES 359 



been of a standard character, and the operations at these points will be more 

 fully mentioned in subsequent paragraphs. 



In other parts of the world many striking examples of value of anti-mosquito 

 work have been shown comparatively recently, and several of these will be de- 

 tailed later. 



In the pages that .follow the aim has been to give a full consideration to the 

 subject of remedies and preventives, discussing not only those which have been 

 found to be of the greatest value, but also others of lesser or even no value, since 

 an expression of opinion concerning all may well be considered desirable. A 

 large part of the following information has been published by the senior author 

 under the title " Preventive and Eemedial Work Against Mosquitoes " as Bull. 

 88, U. S. Dept. Agr,, Bur. Ent., 1910. For a condensed summary of the best 

 remedies the reader is referred to Farmers' Bulletin 444 of the U. S. Depart- 

 ment of Agriculture, which may be had for the asking. 



PROTECTION FROM BITES. 

 SCREENS AND CANOPIES. 



Such obvious measures as the screening of houses, the use of netting for beds 

 and the wearing of veils and gloves after nightfall in badly infested regions, 

 need no consideration in detail. But even in such an apparently simple matter 

 as house screening certain points must be taken into consideration. It may 

 be incidentally stated that with proper treatment of breeding-places screening 

 is unnecessary. The expense to which the people of the United States go for 

 screens against mosquitoes and flies is enormous, and has been estimated at 

 $10,000,000 annually. 



In screening a house, as Doctor John B. Smith has pointed out in his Bulletin 

 No. 216 of the New Jersey Agricultural Experiment Station, the attempts fre- 

 quently fall far short of protection : 



" Adjustable, folding, or sliding screens are never tight, and when the insects 

 really want to get indoors they work their way patiently between the two parts 

 of the screen or between its frames and the window. But even a well-fitted 

 screen either sets tightly into the frame or, running like a sash, may offer leaks 

 when a window is only partly opened. . . . There is abundant opportunity for 

 the insect to get in between the net and lower cross bar ; in fact, there is no real 

 protection at all. Where the netting is fixed to the outside of its frame, so that 

 there is no space between it and the lower part of the sash, the insects neverthe- 

 less find their way in between the window sashes. ... It has been already said 

 that the mosquitoes will, in certain seasons, attempt to make their way through 

 the screens, and they have less trouble with wire netting than with any other 

 because the meshes are even in size and the strands smooth. Some of the fabrics 

 used for nettings, especially of the cheaper grades, have the threads so fuzzy that 

 it is simply impossible for the mosquitoes to make their way through, and they 

 rarely even try it except where there is a tear, or where the threads have been 

 spread apart leaving an unusually large opening. Where an onslaught is made 

 on wire netting it can be checked by painting lightly with kerosene or oil of 

 citron ella. I have tried both and found them successful." 



In addition to these mechanical difficulties it often happens that the cellar 

 and attic windows of houses are not screened. This is a great mistake, since 



