——— 
17 
in the last two or three years, however, the use of these oils in the 
pure state has come into very general vogue, more particularly as 
winter washes for the San Jose seale and allied scale insects, the value 
of the crude oil being especially demonstrated by Prof. J. B. Smith. 
The petroleum oils may also be used mechanically combined with water 
by means of especially adapted spray pumps. 
In addition to its use as a direct application to plants, kerosene is 
often used as a means of destroying insects by jarring the latter from 
plants into pans of water on which a little of the oil is floating, or 
by jarring them upon cloths or screens saturated with kerosene, pref- 
erably the crude oil. The same principle is illustrated in some of 
the hopper-dozers, or machines for collecting locusts and grass-leaf 
hoppers. 
As a remedy for mosquitoes, kerosene has proved very effective. 
It is employed to destroy the larvee of the mosquitoes in their favorite 
breeding places in small pools, still ponds, or stagnant water; and 
where such bodies of water are not sources of drinking supply or of 
value for their fish, especially in the case of temporary pools from 
rains, which frequently breed very disagreeable local swarms, the use 
of oil is strongly recommended. The kerosene is applied at the rate 
of 1 ounce to 15 square feet of water surface. It forms a uniform 
film over the surface and destroys all forms of aquatic insect life, 
including the larve of the mosquito, and also the adult females coming 
to the water to deposit their eggs. The application retains its efficiency 
for several weeks, even with the occurrence of heavy rains. <A light 
grade of fuel oil is preferred for this purpose. 
The methods of using kerosene in the pure state and as emulsions 
with soap and milk follow. 
Pure kerosene treatment.—This consists in spraying the trees with 
ordinary illuminating oil (coal oil or kerosene). The application is 
made at any time during the winter, preferably in the latter part, and 
by means of a spray pump making a fine mist spray. The application 
should be attended with the greatest care, merely enough spray being 
put on the plant to moisten the trunk and branches without causing 
the oil to flow down the trunk and collect about the base. With the 
use of this substance it must be constantly borne in mind that careless 
or excessive application of the oil will be very apt to kill the treated 
plant. The application should be made on a bright, dry day, so that 
the oil will evaporate as quickly as possible. Ona moist, cloudy day 
the evaporation is slow, and injury to the plant is more apt to result. 
If the kerosene treatment be adopted, therefore, it must be with a full 
appreciation of the fact that the death of the tree may follow. This 
oil has been used, however, a great many times and very extensively 
without any consequent injury of any kind. On the other hand, its 
careless use has frequently killed many valuable trees. Its advantages 
16871—No. 127—01 2 

