SULPHUR DIOXIDE AS AN INSECTICIDE. 139 



SULPHUR DIOXIDE AS AN INSECTICIDE. 



By C. L. Maklatt, Washington, D, G. 



The fumes of burning sulphur, namely, sulphur dioxide with some 

 sulphur trioxide, have long been one of the standard insecticide 

 gases for the disinfection of rooms or dwellings of certain insect 

 pests. Brimstone fumigation was urged by Dr. J. A. Lintner as a 

 means of controlling the bedbug (Oimex lectularius L.) where liquid 

 applications were inadvisable, and within the last few years Dr. 

 Ch. Wardell Stiles, of the Bureau of Public Health and Marine- 

 Hospital Service, has very successfully fumigated and disinfected 

 frame cottages at a seaside resort for bedbug infestation by the sul- 

 phur treatment, burning the sulphur at the rate of 2 pounds of stick 

 sulphur for each 1,000 cubic feet of space. Sulphur candles for such 

 fumigation and for disinfection are a standard supply material to 

 be purchased anywhere. 



Sulphur has long been also one of the standard means of disin- 

 fection of premises or goods from disease germs, and in the later work 

 against the Stegomyia calopus conducted by the Yellow Fever Insti- 

 tute of the United States Public Health and Marine-Hospital Service 

 various experiments with sulphur as a means of destroying mosqui- 

 toes in houses were tried and the following conclusions reached : 

 " From the limited number of experiments made and from previous 

 experiments, we consider sulphur dioxide the best of the gaseous 

 insecticides for this purpose." The other means tested included the 

 fumes of tobacco, pyrethrum, and formaldehyde gas. 



The chief objection to sulphur fumigation for insecticide or other- 

 work is the strong bleaching action of these fumes in the presence of 

 moisture and their powerfully destructive action on vegetation. This 

 latter effect has been exhibited very emphatically in the last few 

 years in the large devastated areas surrounding the works of various 

 smelting companies, where a great deal of sulphur is given off from 

 the reduction of sulphide ores. As shown by the investigation of this 

 sort of damage by Mr. J. K. Haywood, of the Bureau of Chemistry 

 (see Bulletin 89 of that Bureau), the sulphur fumes given off from 

 such reducing works are the same as those generated in the burning 

 of stick sulphur, and their action is so powerful as to practically 

 exterminate forests and other vegetation to a distance of from 2 to 9 

 miles about the smelting plants. Referring to the form in which the 

 sulphur is given off, Mr. Haywood says: 



For each pound of sulphur burned 2 pounds of sulphur dioxide are formed 

 and given off into the atmosphere, a part of which acts directly on the foliage 

 of the trees. Sooner or later, however, all of the sulphur dioxide is changed by 

 the action of the oxygen of the air into sulphur trioxide, and it is in this form 



