32 PREVENTIVE AND REMEDIAL WORK AGAINST MOSQUITOES. 



The pungent odor of burning pyrethrum is not disagreeable to 

 most people, but to some it is disagreeable, and with certain sus- 

 ceptible individuals it produces headache. It is apparently possible, 

 however, to volatilize the oil without producing the actual smoke. 

 Mr. H. W. Henshaw, of the Bureau of Biological Survey, United States 

 Department of Agriculture, informs the writer that a few years ago 

 a man in Hawaii patented an appliance for producing this volatiliza- 

 tion which is all that can be wished for. The powder is placed on 

 a brass or other metal screen above the chimney of a kerosene lamp, 

 the idea being to dissipate the vapor of the volatile oil. According 

 to Mr. Henshaw the effect of this method is most remarkable. " Be- 

 sides being very economical in powder there is only a very slight 

 odor perceptible and that is not at all unpleasant. The effect on 

 the mosquitoes is immediate and all that can be wished for. They 

 simply clear out." Another method of burning the powder that has 

 often been employed by the writer consists in puffing it from an in- 

 sufflator into a burning gas jet. This is a simple method where 

 gas is used for illuminating purposes and produces a vapor that 

 suffocates all mosquitoes and other insects that may be in the room. 



While pyrethrum has been mainly used as a means of clearing 

 living rooms of mosquitoes, and has ordinarily been burned m the 

 rooms while they were occupied, it has also come into use in the 

 extensive fumigation of houses in cases of epidemics of yellow fever, 

 in the effort to rid houses of malarial mosquitoes, and to destroy 

 all mosquitoes hibernating in cellars, attics, or disused rooms of 

 residences, as well as similar hibernating mosquitoes in barns and 

 outhouses. While reasonably effective for such purposes, it does 

 not seem to be as effective as some of the other substances to be 

 mentioned later and at the same time it is more expensive. 



As to the quantity to be used, the regulations of the board of health 

 of New Orleans, adopted May 25, 1903, specify the burning of 4 ounces 

 of pyrethrum powder to 1,000 cubic feet of space; but the president 

 of the board, Dr. Eclmond Souchon, a little less than a year later 

 wrote to the United States Marine-Hospital Service that this quan- 

 tity was found insufficient for thorough work, and that 1 pound 

 of the powder to every 1,000 cubic feet of space is necessary. As a 

 matter of fact, however, the New Orleans board of health aban- 

 doned pyrethrum about that time, on account of the fact that the 

 fumes do not kill mosquitoes but simply stupefy them, so that they 

 have to be brushed up and burned. Not willing to run the slightest 

 chance of having mosquitoes survive by escaping destruction after 

 being stupefied, the board decided to use sulphur fumes in preference. 



Nevertheless, on account of the fact that the fumes are not noxious 

 to human beings, there still remains a decided use for pyrethrum in 

 everyday work in mosquito-inhabited regions. 



