REPORT OF THE STATE ENTOMOLOGIST I9OO 983 



prevent leakage of the gas at the bottom. A short, uncovered space was 

 always left, preferably on the windward side, for the insertion of the 

 chemicals, which were put in a stoneware crock The necessary amount 

 of sulfuric acid was diluted by turning it into the proper amount of 

 water, taking care to keep the water stirred while adding the acid. The 

 crock containing the diluted acid was then placed near the center of the 

 tent but not close to the tree, and the potassium cyanid, previously put 

 in a small bag, was dropped into the acid. The uncovered portion of the 

 sod cloth was quickly buried with earth and the gas allowed to act about 

 35 minutes. The lines guying the tent were then released, the sod cloth 

 uncovered and the tent quickly raised and dropped over an adjacent 

 tree. It is quite important to have the pole ©n the windward side ot the 

 tent so far as possible, and every precaution should be taken to avoid in- 

 haling the deadly gas. 



The trees were fumigated Ap. 19, 20 and 21, using i ounce of potas- 

 sium cyanid to 75, 100 and 150 cubic feet of space respectively. It was 

 planned to fumigate all the trees in one day, but a good breeze and 

 trouble with the outfit compelled the extension of the work over a space 

 of three days. 



Otie ounce of cyanid to 1^0 cubic feet. Four trees were treated with the 

 gas, using i ounce of cyanid of potassium to 150 cubic feet of space. 

 The condition of the trees prior to the beginning of the experiment was 

 as follows. Tree 84, a globe peach 9 feet high, was moderately infested 

 with the scale. Tree 85, an old Mixon peach 12 feet high, was badly in- 

 fested with the scale. Tree 106, a Vermont beauty pear 10 feet high, was 

 moderately infested, and tree 115, a Bartlett pear 11 feet high, was badly 

 infested. 



Ap. 20. Tree 106 was treated. The buds were starting a little. The 

 day was bright, and the exposure to the gas was from 2.35-3.10 p. m. 

 Equal amounts of the cyanid and sulfuric acid were used and thrice the 

 amount of water, the two latter being measured in liquid ounces. 



Ap. 2 1. It was cloudy and still while the fumigation of these three 

 trees was in progress. Tree 84 was fumigated from 9.44-1 0.19 a. m., 

 using 2\ ounces of cyanid, 3! ounces of sulfuric acid and 7^ ounces of 

 water. This reaction was perfect as the cyanid was turned from the bag 

 into the diluted acid. The buds were starting a little. Tree 85 was 

 fumigated from 9.02-9.37 a. m., the same amounts of the chemicals being 

 used as with tree 84. The reaction was very poor, only a part of the 

 cyanid being acted on, which was probably on account of the protection 

 afforded by the bag. Tree 115 was fumigated from 10. 49-1 1.24 a. m., using 

 the same amounts of chemicals as on the preceding two. 



