388 MOSQUITOES OF NORTH AMERICA 



larvae, and for small collections of fluid, cesspits, etc., is highly effective, and 

 though killing off most forms of animal life does not render the "water as putrid 

 or offensive as the use of oils. When fish are present these would be destroyed, 

 and therefore this method is not advisable in larger collections of water." 



SALT. 



During the 1905 outbreak of yellow fever in New Orleans an attempt was 

 made to destroy mosquito larvae in the open gutters of the city by the use of 

 common salt. Dr. H. A. Veazie wrote us that the results were good where the 

 work was properly done. Shortly after operations were begun there was a flight 

 into the city of Aedes soUicitans from the salt marshes northeast of New Orleans. 

 Indignant citizens ascertaining from experts the name and habits of the species 

 jumped to the conclusion that salting the ditches had brought about suitable 

 breeding conditions for soUicitans and that the invasion of the city by that 

 species was a direct result of the work of the sanitary officials. 



ABOLITION OF BREEDING-PLACES OF HOUSEHOLD MOSQUITOES. 



In considering this question, just as in considering so many questions relating 

 to mosquitoes, a complication arises from the diversity of facts concerning the 

 life-histories of the different species of mosquitoes, facts discovered, for the 

 most part, within the past ten years. At the time of the publication of Bulletin 

 25, New Series, Division of Entomology, U. S. Department of Agriculture, in 

 1900, the habits of but a very few species of mosquitoes were known and the 

 generalizations drawn from the knowledge of these few species were altogether 

 too broad and must now be greatly modified. The breeding-places of different 

 species are quite peculiar. Those of the commonest household mosquitoes, 

 namely Culex pipiens in the North and Culex quinquefasciatus and Aedes 

 calopus in the South, correspond best with the generalizations formerly made, 

 breeding as they do in every receptacle of water about residences, and the 

 abolition of all such accumulations of water means their destruction. Where 

 the rain-water barrel or the rain-water tank are necessary they should be 

 screened. In New Orleans and other southern cities the boards of health are now 

 enforcing the screening of these receptacles. The screening should be done with 

 extreme care, a fine mesh screen being used and the fitting made very perfect. 



About a given house the waste places in the immediate vicinity should be 

 carefully searched for tin cans, bottles, wooden or tin boxes in which water can 

 accumulate, and all such receptacles should be destroyed or carted away. The 

 roof-gutters of the building should be carefully examined, to make sure that 

 they are not clogged so as to allow water to accumulate. The chicken-pans in 

 the poultry yard, the water troughs for domestic animals, the water-cup of the 

 grindstone, are all places in which mosquitoes will breed, and in them water 

 should not be allowed to stand for any length of time. In the South the water 

 accumulating under water tanks should be treated or drained away. The 

 urns in the cemeteries at New Orleans have been found to breed mosquitoes 

 abundantly. The holy-water fonts in Catholic churches, especially in the South, 

 have commonly been found to breed mosquitoes ; in some places sponges have 



