122 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 12 



Dosage — -Approximately sched- 

 ule I for sodium cyanid. 



Exposure — 1 hour. 



Temperature — 66° . 



Inspectors — R. S. Woglum, 

 M. B. Rounds. 



The results of these two experiments demonstrate that the scale-kill 

 with liquid hydrocyanic acid as at present used is decidedly better 

 toward the lower part of the tent than toward the top. This result 

 was plainly shown in each of the trees which comprised these tests 

 as well as in the totals. Scale-infested units within. a few inches of 

 the ground showed a higher mortality than units in the tops of tall trees. 



Table III 



A comparison of these results as summarized in Table I with those 

 obtained by MorrilU and Quayle^ for gas generated in pots is both 

 interesting and instructive: 



(o) Average percentage of 7 trees with purple scale. 



(b) Average percentage of 6 experiments with citrus white fly on large trees. 



(c) Results of 121 experiments with the bean and granary weevils under tent form 

 about 12 feet tall. 



The conclusion reached by both Morrill and Quayle for pot-gen- 

 erated gas is that the kilhng effect is decidedly better toward the top 

 of the tree than the bottom. 



A striking difference between these results and those with hquid 

 hydrocyanic acid is shown, the mortality with the latter being decidedly 

 the greatest toward the bottom of the tent. In fact, the percentage of 

 mortality for hquid hydrocyanic acid in favor of the bottom of the tent 

 is almost inversely proportionate to Morrill's results with pot fumiga- 

 tion for the top. It should be noted that the experiments with liquid 



1 U. S. Dept. Agr. Bur. Ent. Bull. 76, p 51. 

 2Jr.Econ.Ent. 11,3, 1918. 



