37 



treated with the lime, sulphur, and salt wash. This treatment had 

 been made in the winter or early in the spring, before the trees had 

 begun to leaf out, and at the end of August the trees were still dis- 

 tinctly whitened by the application, there having been no rains in the 

 interim to remove it from the bark. Under such circumstances it is 

 plainly to be seen that this wash has the maximum chance of effective- 

 ness, and that it is thoroughly effective under these conditions is beyond 

 question. Its effectiveness is undoubtedly, in the first mstance, chiefly 

 due to the direct insecticidal action of the mixture; and possibly, 

 secondarily, in protecting the tree by the limy and sulphurous coating, 

 which remains for months and is undoubtedly distasteful to the young 

 scales coming from old individuals which may have escaped, and 

 perhaps retains enough of its insecticidal value to destroy many of 

 them. 



Bordeaux mixture kerosene emulsion. — This mixture, suggested by 

 Professor Galloway, is an attempt to emulsify a small amount of kero- 

 sene in a comparatively large amount of Bordeaux wash. The for- 

 mula used was- — 



Gallons. 



Bordeaux mixture 5 



Kerosene 1 



The two are churned together until the oil is emulsified. Some peach 

 trees infested with Diaspis pentagona were sprayed with this mixture 

 on April 11. At the time of the application the trees were just com- 

 ing out in leaf and bloom. The weather conditions immediately fol- 

 lowing the application were favorable, no rain falling on the 15th or 

 16th. There was a good deal of rain, however, between April 17 and 

 22. This mixture seemed to have little effect on the trees, and also 

 little effect, if any, on the scale insect. It must be remembered that 

 the Diaspis has an unusually thick scale, and is therefore more than 

 ordinarily protected and correspondingly immune from the action of 

 insecticides, as was illustrated in the preceding experiment with the 

 lime, sulphur, and salt wash, where not above 50 per cent of this 

 Diaspis was killed by a wash that completely exterminated the San 

 Jose scale. The testing of this mixture has not, therefore, been 

 wholly satisfactory, and it is probably worth while to do some more 

 work with it in the future with other scale insects. 



Kerosene-lime emulsion. — This mixture, recommended to the writer 

 by Professor Galloway some years ago and experimented with in a 

 limited way at the time, was again brought to his notice by Professor 

 Galloway, who prepared for his use an emulsion after the following 

 formula: 



Fresh lime pounds. . 4 



Water .gallons. . 5 



Kerosene _.„„ do 1 



