DISINFECTING NURSERY TREES 483 



To destroy yellow jackets by trapping and poison is also feasible. 

 W. F. Moyer, of Napa, proceeds in this way : 



Make a thin fruit syrup by mashing the boiling ripe fruit, strain it and add 

 a little sugar. Place the soup dishes on the drying ground where the "jackets" 

 are thickest. When the top of the syrup is covered with drowned and drowning 

 "jackets," scoop them out with the hand and crush them with the foot. They 

 won't sting unless you pinch ihem. As the syrup evaporates fill up the dishes 

 with water. If a day or two should elapse when no fruit is cut, be sure the 

 traps are well cared for, as they will swarm around them thicker than ever, 

 especially if the weather is hot. For dishes to place the syrup in, cut kerosene 

 cans so as to make two cans, each about six and one-half inches deep. 



Poisoning to carry destruction to the young brood is also practicable. 

 Dr. J. H. Miller, of San Leandro, saved his fruit in this way : 



I bought half a dozen beef livers, five pounds of arsenious acid and several 

 pounds of baling wire. Cutting the liver into pieces as large as a man's fist, I 

 put them into a hot solution of arsenious acid, and, bending the wire into a hook 

 at each end, I suspended the pieces from the lower limbs of trees all around 

 my drying-ground. The fruit was soon deserted, and the little insects busily 

 working at the fragrant liver. The insects carried pieces of the liver up to their 

 nests, and besides causing the death of those that had been destroying my fruit, 

 the next generation of yellow jackets was also destroyed, and so complete was 

 the destruction that there were not enough of the little pests in that neighborhood 

 the following year to require a repetition of the treatment. There is no risk 

 in so using the poison, for the yellow jackets will not return to the fruit, and 

 bees will not go near the meat. 



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 may be done 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 linseed 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 remains so for one hour. 



INSECTICIDES 



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 Experiment Station at Berke- 



