97 
DISINFECTION EXPERIMENTS. 
A few tests were made to determine the relative efficiency of sul¬ 
phur dioxid, tobacco smoke, and pyrethrum as insecticides with par¬ 
ticular reference to the Stegomyia fasciata. 
A small room and hallway containing 1,200 cubic feet of air space 
were used in these experiments. The room contained a large window 
and one door, which were made reasonably tight to prevent the escape 
of the fumes, and the mosquitoes were exposed in cages in various 
parts of the room. 
Experiment No. 1 — Tobacco .—One pound of tobacco per 1,000 
cubic feet; exposure, one hour; result, some mosquitoes survived. 
Six hundred and twenty-five grams of tobacco, which is about the 
proportion of 1 pound per 1,000 cubic feet, were burned in a pan in the 
center of the room. The cages containing the mosquitoes were placed 
on the floor, near the ceiling, and on a chair. 
The room was opened one hour after the tobacco was lighted, 
which was done by means of alcohol. The mosquito cages were 
immediately removed and placed in a current of fresh air in order to 
give the mosquitoes a favorable opportunity to revive. 
All the mosquitoes in the cage which was near the ceiling were dead. 
Of those in the cage on the chair, one female was flying actively 
about; the other females and another male were all dead. Those in 
the cage that stood on the floor were stupefied, but none was killed, 
most of them living actively about. 
The tobacco was completely consumed in this process, and the 
fumes upon opening the door were very strong. The unpleasant odor 
was very persistent and disagreeable. 
Experiment No. 2 — Tobacco .—Two pounds per 1,000 cubic feet; 
exposure, two hours; result, all mosquitoes killed. 
The mosquito cages were immediately removed after two hours had 
elapsed, at which time none of the insects showed apparent signs of 
life; but after remaining in the fresh air for three hours a few of 
them moved their wings and tarsi. None, however, revived. 
Experiment No. 3 — Pyrethrum .—Two pounds per 1,000 cubic feet; 
exposure, 2 hours; result, all mosquitoes killed. 
The pyrethrum was burned in a brazier placed upon some sand, on 
the floor. 
Three cages containing many mosquitoes were distributed, one on 
the floor, one near the ceiling, and one in an open box on the table. 
The cages had a piece of crumpled gauze upon the bottom and a 
folded handkerchief hanging in the cage, in order to give the insects 
retreats in which to hide from the effects of the fumes and to test 
the penetrating action of the gas. 
All of the mosquitoes were killed. 
