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JOURNAL OF ECONOAIIC ENTOAIOLOGY 



IVol. 8 



In conclusion of this brief consideration of the poison sprays it 

 should be said that in ever}^ case much benefit was derived from them 

 in protecting the foliage and enabling the trees to develop fruit buds 

 for the subsequent season. Nor is this to be considered of little mo- 

 ment or of slight importance. At the same time, fruit buds are of 

 little value if they are so eaten by insects that they cannot develop 

 into fruit. 



Experiments with Miscible Oils to Destroy the Eggs 



In the spring of 1913 we planned and carried out a series of experi- 

 ments in a badly infested orchard with the miscible oils, using Scalecide 

 and the Orchard brand manufactured by the Thompson Chemical 

 Company. In all, thirty large russet trees were included in the experi- 

 ment and carefully sprayed with the oils at the proportions of 1 to 15. 

 In addition to these trees included in the actual experiment many 

 more were sprayed by the owner with Scalecide at the rate of 1 gallon 

 to 15 gallons of water. 



The oils were ai3plied April 2 and 3, of course, before the buds had 

 started, although they had begun to swell. Unfortunately, it rained 

 hard in the afternoon of April 3 and the oil applied that morning had 

 been on only four hours, while the oil applied the day before only 

 about twenty-four hours. Undoubtedly this influenced the final 

 results. 



On May 13, I made a rather extensive and tedious count of the 

 eggs killed by the oil in different masses. In the experimental rows 

 the masses were taken mostly from the row that was sprayed in the 

 forenoon of the day on which it rained in the afternoon. We w^ere not 

 aware of this until we consulted our notes later. The results of the 

 count showed that a fraction over 76 per cent of the eggs had been 

 destroyed and did not hatch. In that part of the orchard sprayed by 

 the owner a more extensive count of egg masses showed that prac- 

 tically 79 per cent of the eggs had been killed. 



The general effect of the spraying with the miscible oils was better 

 than we hardly dared hope. In the first place, there is no appearance 

 in the orchard of injury caused by the oils. We were careful to make 

 the applications just as near the active growing period of the trees as 

 possible. Moreover, the spraying was done in moderately warm 

 weather. The orchard bore a fair crop of fruit and the owner is much 

 encouraged. 



Gill, in his work in Colorado with the miscible oils killed a much 

 higher percentage of the eggs. Gillette and Weldon in Colorado 

 succeeded in killing 95 per cent of the eggs. From their accounts it 

 appears that the trees were more thoroughly drenched than were the 



