662 DOMESTIC ANIMALS, DAIRYING, ETC. 



Fountains and ornamental ponds are frequent breeding places, 

 and here the introduction of fish, as indicated in another place, is 

 usually all-sufficient. It frequently happens, however, that the. 

 grass is allowed to grow down into the edges of ornamental ponds 

 and mosquito Iarva3 find refuge among the vegetation and so escape 

 the fish. Broad-leaved water plants are also often grown in such, 

 ponds, and where these broad leaves lie flat upon the surface of the 

 water, as they frequently do, one portion of a given leaf may be 

 submerged so that mosquito larvao may breed freely in the water 

 over the submerged portion of the leaf, protected from fish by the 

 leaf itself, the fish rising from below. It is necessary, therefore, to 

 keep the edges of such ornamental ponds free from vegetation and 

 to choose aquatic plants whose growth will not permit of mosquito- 

 larvae protection. In many small country towns, even where there 

 is a water supply, tanks are to be found under the roofs to supply 

 bathrooms. Such tanks should be screened, since mosquitoes gain 

 entrance to the tank-room either through dormer windows or by 

 flying up through the house from below in search of ovipositing 

 places. About a large old house there are so many of these chance- 

 breeding places that only the most careful and long-continued 

 search will find them all. Frequent change of water or the use 

 of kerosene will render them all harmless. 



In community work in cities all of the points mentioned must 

 be borne in mind, and in the portions of the community where the 

 residences are for the most part detached villas, in the absence of 

 swampy suburbs the householders are in the main responsible for 

 their own mosquitoes. There are, however, breeding places for 

 which the municipality may be said to be responsible and these 

 entirely aside from public fountains, reservoirs, or marshes. It 

 seems unlikely that in any general sewage system mosquitoes may 

 breed in the sewers proper. That they do breed in the catch-basins 

 is well known. The purpose of the catch-basin is to catch and retain 

 by sedimentation sand and refuse which would otherwise enter the 

 sewer and deposit in it. It is intended to be watertight and to hold 

 a considerable body of water which stands in it up to the level of 

 the outlet pipe. Such catch-basins are very commonly used in back 

 yards and at the crossings of streets. The water is removed only 

 by rain or when street or yard surfaces are washed. In dry seasons 

 the period of stagnation may last several weeks, certainly long 

 enough for mosquito breeding. As a matter of fact, mosquitoes in 

 midsummer do breed in such basin traps or catch-basins by mil- 

 lions. 



PROTECTION FROM BITES. 



Protective Liquids. A number of different substances have 

 been in use to rub upon the skin or to put near the bed as a pro- 

 tection from mosquitoes. Spirits of camphor rubbed upon the face 

 and hands, or a few drops on the pillow at night, will keep away 

 mosquitoes for a time, and this is also a well-known property of oil 

 of pennyroyal. Oil of peppermint, lemon juice, and vinegar have 

 all been recommended for use as protectors against mosquitoes, 



