366 MOSQUITOES OF NORTH AMERICA 
drops rubbed on the face and hands will suffice. This mixture in the experience 
of the writer has been efficacious against all mosquitoes except Aédes calopus, 
the yellow-fever mosquito. This mosquito begins to trouble the sleeper at day- 
break and by that time the efficacy of the mixture has largely passed, and one 
is apt to be in his soundest sleep. If, however, one could arrange to be awakened 
just before day-break and apply the mixture, returning for the last nap, it is 
probable that it would be efficacious. 
Fishermen and hunters in the north woods will find that a good mixture 
against mosquitoes and black flies can be made as follows: 
Take 24 lbs. of mutton tallow and strain it. 
While still hot add: 4 1b. black tar (Canadian tar). 
Stir thoroughly and pour into the receptacle in which it is to be contained. 
When nearly cool stir in 8 oz. of oil of citronella and 14 02. of pennyroyal. 
Oscar Samostz, of Austin, Tex., recommends the following formula: 
1 oz. oil citronella. 
4 oz. liquid vaseline. 
Apply freely to exposed parts. 
Mr. B. A. Reynolds, of the Bureau of Entomology, has used successfully in 
New Orleans 20 minims of oil of citronella to the ounce of vaseline or lanoline, 
preference being given to the latter. 
Doctor Durham, of the English Yellow Fever Commission to Par4, Brazil, 
told the writer that he and the late Doctor Myers found that a 5 per cent solution 
of sulphate of potash prevented mosquitoes from biting, and that they were 
obliged to use this mixture while at work in their laboratory in Brazil to pre- 
vent themselves from being badly bitten. 
An anonymous correspondent of “ American Medicine,” who signs himself 
F. A. H., says: 
“T would advise the use of the oil of cassia, for the odor is not offensive to 
human beings and it is an irritant poison to all kinds of insects. Besides, its 
power remains for a long time after it has dried.” 
Pure kerosene has been used for this same purpose. An excellent example 
of its practical use came to the writer in a letter from Dr. W. H. Dade, an 
Army Surgeon, writing from the Philippine Islands under date of November 
15,1901: 
He stated that during November, 1900, while traveling up the Cagayan 
River on the steamer Raleigh, they were bothered greatly by mosquitoes, both 
during the day and night, Culex and Anopheles both being present and breed- 
ing in fire buckets along the sides of the vessel. The buckets were teeming with 
larve. They did not seem to have thought of putting kerosene in the buckets 
in order to stop the breeding, but at the suggestion of Doctor Dade a rag was satu- 
rated with kerosene, the face, hands and feet were smeared with it and the rag 
was put where it could be conveniently reached. When aroused from sleep by 
mosquitoes another application was made. “ Those who had not used these 
means before seemed perfectly surprised at the splendid immunity gained. The 
odor and the greasy feeling imparted were the only drawbacks to its use.” 
