Treatment of Nursery Stock. 455 
spray. Sometimes the insects are driven away by dense smoke 
from fires in and around the orchard. 
The Dried Fruit Worm.—Dried fruit is often seriously in- 
jured after packing, by a small worm, larva of a moth not yet 
determined. The eggs are deposited-on the fruit either while 
drying or while in the packing-house, or through the cloth of 
the sacks, or seams of the package. The eggs may be killed on 
the fruit before packing, by dipping in boiling water, or by heat- 
ing in an oven and after that preventing the access of the moth. 
Infested fruit can also be treated by bisulphide vapor, the method 
being the same as described for nursery stock below. 
DISINFECTING NURSERY STOCK. 
Cuttings, scions, young trees and vines, etc., can be freed 
from insects by inclosing in a tight box or cask and placing a 
saucerful of carbon bisulphide on the top of them, covering it 
with canvas or any tight-fitting cover. The bisulphide vapor 
will destroy all insect life in forty minutes. 
Disinfecting such materials on a larger scale is done by 
Alexander Craw, State quarantine officer, in this way:— 
Use square canvas sheets, sixteen to twenty feet in diameter, made 
of the best ducking, double stitched and then painted with boiled lin- 
seed oil to make it-gas proof. The canvas must be perfectly dry before 
it is rolled up, or it is liable to be destroyed by spontaneous combustion. 
To fumigate evergreen stock use one ounce of cyanide of potassium (in 
lumps, not pulverized), one fluid ounce of commercial sulphuric acid, 
and two fluid ounces of water to one hundred cubic feet of enclosed 
space. For deciduous and hardy trees, when dormant, use one-fourth 
more of each of the above. When the canvas has been placed over the 
stock to be fumigated, prepare the charge. Take a three or four-gallon 
glazed earthenware jar, into which pour the necessary quantity of water, 
then the sulphuric acid, and place it well under the canvas, the edges of 
which are secured with soil or in some way so as to prevent the gas 
escaping, with the exception of the edge immediately in front of the 
jar. The proper amount of cyanide of potassium is then dropped into 
the jar from a long scoop, and the tent is immediately closed, and re- 
mains so for one hour. 
It is hoped that this chapter will convey useful hints in the 
warfare against insects. Whenever questions arise which are 
not met thereby, appeal should be made to the University Exper- 
iment Station at Berkeley. 
