
17 
In making the lye-sulphur wash, first mix 20 pounds of flowers of 
sulphur into a paste with cold water, then add 10 pounds of pulver- 
ized caustic soda (98 per cent). The dissolving lye will boil and 
liquefy the sulphur. Water must be added from time to time to pre- 
vent burning, until a concentrated solution of 20 gallons is obtained. 
Two gallons of this is sufficient for 50 gallons of spray, giving a 
strength of 2 pounds of sulphur and 1 of lye to 50 gallons of water. 
An even stronger application can be made without danger to the 
foliage. This mixture can also be used in combination with other 
insecticides. 
The chemical combination of sulphur and lime known as sulphid 
of lime is perhaps a better liquid sulphur solution than the last as a 
remedy for mites. It may be very cheaply prepared by boiling 
together for an hour or more, in a small quantity of water, equal 
parts of flowers of sulphur and stone lime. A convenient quantity is 
prepared by taking 5 pounds of sulphur and 5 of lime and boiling in 
8 or 4 gallons of water until the ingredients combine, forming a 
brownish liquid. This may be diluted to make 100 gallons of spray. 
Almost any of the insecticides with which the sulphur may be 
applied will kill the leaf or rust mites, but the advantage of the 
sulphur arises from the fact that it forms an adhering coating on the 
leaves and kills the young mites coming from the eggs, which are 
very resistant to the action of insecticides. 
A strongly intrenched popular fallacy, often exposed but con- 
stantly being revived, is that sulphur is a valuable remedy against 
insects when put into holes bored into the trunks of trees, the idea 
being that the sulphur, when plugged in, is carried up by the move- 
ment of the sap into the branches and distributed in the foliage, 
rendering the latter distasteful to msects. In point of fact, the 
sulphur remains exactly where it is placed, and is of no possible 
advantage from an insecticide standpoint or any other, and further- 
more the treatment is mischievous in that it injures to that extent 
the soundness of the trunk. 
PETROLEUM OILS. 
The emulsions of kerosene, or coal oil, with soap or milk have long 
been the standard insecticides for external sucking insects, and espe- 
cially the aphides and scale insects, and these emulsions still are the 
safest and most reliable means of getting these oils upon plants. The 
use of kerosene in the pure state as an insecticide was early experi- 
mented with by Comstock and Hubbard, and the feasibility of such 
applications was demonstrated, but the greater safety in the use of 
the emulsions resulted in a discontinuance of the use of the pure oils. 
Especially during the last twelve years, however, the use of these 
73159—Bul. 127—09—_3 
