February, '16] wellhouse: cyanide inoculation 169 



I have never heard of any such attack upon barlej^ or oats in North 

 America, and wish that my hearers would bear the matter in mind next 

 summer and see if any such injury can be found. Our species mine in 

 the stems of grains and grasses, but we seem to have none that feed in 

 kernels of grain. 



President Glenn W. Herrick: We have one more paper this 

 afternoon which will be presented by Mr. Hunter. 



RESULTS OF EXPERIMENTS ON THE USE OF CYANIDE OF 

 POTASSIUM AS AN INSECTICIDE 



By Walter WELLHorsE, University of Kansas, Lawrence, Kansas 



In view" of the number of reports, mostly favorable/ w^hich have 

 been published recently regarding the efficiency of cyanide of potassium 

 as an insecticide against borers and plant parasites, when injected 

 into the tissues, it seemed desirable to carry on some experiments on 

 this question in Kansas. 



Accordingly, at the instance of Professor S. J. Hunter, of the Univer- 

 sity of Kansas, and under his direction, preliminary experiments to 

 ascertain the effect of cyanide of potassium on plant tissues and on 

 scale insects were begun March 13, 1915. 



It w^as thought best to use first, tender house plants, on w^hich the 

 effects could be seen at once. Twenty-five coleus plants infested with 

 mealy bugs (Dadylopius) were secured from a greenhouse. Fifteen 

 of these coleus plants were treated with potassium cyanide, 98 per 

 cent pure. With a sterifized needle an incision was made in the stem 

 of each plant, a cyanide crystal weighing from one-half milligram to 

 three milHgrams was inserted into the incision, which was immediately 

 sealed with paraffine. In from two to three hours later the tissues 

 bordering the hole where the cyanide had been placed began to turn 

 dark brown and within a couple of days the stem at this point was 

 shrunken and bent. The tissues seemed to be cauterized by the 

 cyanide. The mealy bugs continued to grow and multiply even 

 on the very portion of the stem W'here the cyanide was injected. 

 Several plants used as checks were punctured with the needle and 

 the puncture covered with paraffine but no cyanide was used in them. 

 They showed no signs of injury from the treatment. 



Then we determined to try the experiment on trees infested with 

 borers. A number of different species of trees on and near the campus 

 were selected. The trees chosen were elm, apple, pear, plum, apricot, 

 osage orange, ailanthus, willow and pine. Over fifty trees were used 



•Science," Oct. 9, Dec. 11, 1914; Feb. 5, Feb. 26, 1915. 



