TOXIC GASES AS A CONTROL OF THE PEACH-TREE BORER. 23 
For G to 15 year old trees of average size, doses of 1 ounce 
and of three- fourths of an ounce per tree have been found effective in 
destroying the borers without injury to the trees. For very large 
trees of advanced age, a somewhat increased dose may be desirable. 
As an added precaution against injury the base of the trees should 
be uncovered 4 to 6 weeks after application, allowed to remain open 
for a few days, and recovered. This precaution is especially neces- 
sary if the application has been made very late. 
The use of p-dichlorobenzene in this way has been found to reduce 
the infestation on the average from 6.77 to 0.41-0.36 larvae per tree, 
approximately a 94 per cent control. 
* 
WASHINGTON : GOVERNMENT PRINTING OFFICE ; 1910 
