INJURIOUS INSECTS OF I909Q AND IQIO. [49 
stock solution in making up the spray mixture, 1 gallon of copper 
sulfate solution represents 1 pound of copper sulfate and 1 gallon 
of lime-water represents a like amount,—more or less, depending 
on the amount of water used in making the stock solution. The 
proper amount of stock solutions should be diluted separately be- 
fore they are poured together. The stock solution of lime should 
be first run through a fine mesh sieve to remove all lumps which 
might clog the nozzle of the sprayer. 
Carbon BisuLFipE: This is a very inflammable liquid 
that volatilizes readily when exposed to the air. It is one of the 
gaseous insecticides used against weevils, etc. 
COPPER SULFATE WASH: 
Copper sulfate, 3 pounds. 
Water, 50 gallons. 
This is used as a wash on dormant trees for prevention of such 
diseases as apple scab. It must never be used on trees after the 
buds have burst. 
CORROSIVE SUBLIMATE: 
Mercury bichloride (corrosive sublimate), 2 ounces. 
Water, 15 gallons. 
This is an extremely poisonous mixture and should be handled 
with great care. It is very effective against potato scab. It should 
not be made in tin vessels as it corrodes them. 
CrupDE PETROLEUM: This is an oily, inflammable liquid 
that when refined yields such products as paraffin, lubricating oil, 
kerosene, etc. A petroleum having a specific gravity of 43 degrees 
(Baume scale), is an excellent insecticide for scale insects. In 
fact it was used very successfully against the San Jose Scale until 
the lime-sulfur wash was found to be better. 
FORMALIN: 
Formalin (40% formaldehyde), one-half pound. 
Water, 15 gallons. 
This is used in treating seed for prevention of such diseases as 
potato scab. 
HELLEBORE: This is a stomach or internal insecticide. It is 
not poisonous to man as are the arsenical insecticides, and therefore 
is used where there is danger of poison remaining on parts to be 
eaten. It is often used on currants and gooseberry bushes when 
the berries are beginning to ripen. This material can be used in 
the dry form, or as a spray at the rate of 2 or 3 ounces to a gallon. 
