20 MISC. PUB. 526, U. S. DEPT. OF AGRICULTURE 
In situations where no domestic or farm animals have access to the 
bait, apply it in piles of about a tablespoonful each, spaced about 2 feet 
apart; otherwise it should be scattered in the infested area as recom- 
mended for applying poisoned-bran bait (p. 28). Unless washed away 
by watering or rains it remains effective for some time, and baiting two 
or three times during the year gives adequate control. Ready-mixed 
baits containing calcium arsenate and metaldehyde are available on the 
market. 
Caution.—Since metaldehyde may cause poisoning when taken 
internally, the containers should be plainly labeled “Poison” and 
kept out of reach of children and others. 
METHYL BROMIDE 
Methyl bromide (CH,Br) at temperatures above 40° F. is a gas that 
is heavier than air. Under pressure it becomes a heavy, colorless liquid 
which is only slightly soluble in water. It is soluble in alcohol, chloro- 
form, ether, and carbon disulfide. Commercially it has some use as a 
fire extinguisher and as a refrigerant. The gas is noninflammable, 
almost odorless, very penetrating, and is poisonous. As commercially 
produced it has a purity of 9914 percent or better. 
For the destruction of insects and mites on plants and in soil methyl 
bromide is being used as a fumigant in specially constructed chambers. 
Under carefully controlled conditions of temperature, exposure, and 
dosage it will destroy these pests without injury to the plants. In 
this respect it is more useful as a general treatment than other fumi- 
gants. 
Special fumigation chambers and special instructions are necessary 
for its proper use. Information on these points can be furnished, to 
those who have need for it, by the Bureau of Entomology and Plant 
eee United States Department of Agriculture, Washington, 
Caution.—When working with methyl bromide it is necessary 
to use a gas mask provided with a canister that will absorb the 
gas. It is toxic, and should not be allowed to come into contact 
with the skin. Containers of this gas should be stored in a cool, 
well-ventilated place outside of inhabited buildings. The gas is 
practically odorless, but dangerous concentrations of it may be 
readily detected by the use of a specially devised halide leak de- 
tector or lamp. 
Methyl bromide is obtainable in small 1-pound cans or in cylinders 
containing 10, 50, or 150 pounds net. 
MINERAL OIL 
Mineral oil, or petroleum oil, is obtained by refining native crude 
oil. Refined petroleum oils used for controlling insects may be di- 
vided into two general types known as dormant oils and summer oils, 
the latter being highly refined products, also called white oils. 
Dormant oils—Dormant oils having a viscosity of from 90 to 150 
seconds (Saybolt, at 100° F.) and an unsulfonatable residue of from 
50 to 70 percent are emulsified at the rate of 2 to 6 gallons per 100 
gallons of water for the control of several fruit insects, such as the 
