New York Agricultural Experiment Station. 441 



clustered on the branches in the lower parts of the trees, which may 

 have been due to varying percentages of oil in the mixtures caused 

 by imperfectly prepared emulsions. The trees subsequently received 

 an application of fish-oil soap which treatment greatly reduced 

 the severity of the infestation, and fewer eggs were deposited in this 

 section than in unsprayed portions of the orchard. 



In the spring of 1911 spraying experiments against the "flies" 

 were conducted in the Kieffer pear orchard of Mr. L. B. Wright at 

 Hilton. The rough bark had been removed from the trees during 

 the previous year, which left small opportunity for the protec- 

 tion of the insects from the sprays. As soon as the adult psyllas 

 appeared the trees were sprayed with either miscible oil at dilutions 

 of 1-10 or 1-15, or fish-oil soap in the proportion of one pound of 

 the soap to four or five gallons of water. About 800 trees were 

 used in these experiments and the treatments resulted in large 

 reductions of the numbers of the " flies " in the orchard. Very little 

 difference in the effectiveness of the various dilutions of miscible 

 oil were observed. A slightly greater benefit resulted from the appli- 

 cation of the 1-10 dilution, which seemed hardly sufficient to com- 

 pensate for the added expense of the treatment. Fish-oil soap in 

 the proportions used gave very satisfactory results. A few " flies " 

 escaped from the treatments but no apparent harm was caused to 

 the planting through the natural increase of the insects as the 

 season advanced. 



In the spring of 1911 experiments along these general lines were 

 conducted in about twenty-five orchards in cooperation with pear- 

 growers. In these tests miscible oils, homemade oil emulsions, and 

 soapy sprays were used either alone or in combination with tobacco 

 solutions, or these latter solutions were used alone. These later 

 experiments have reaffirmed the results of the initial endeavors. 

 Careful application of the sprays in nearly every instance resulted 

 in freeing the trees almost completely from the insects. In occasional 

 plantings, because of adjoining infested orchards, the treatment 

 afforded only partial relief and in such instances it was necessary 

 to resort to a later treatment. Of the mixtures employed, the 

 soap solutions and the tobacco extract (40 per ct. nicotine) with 

 soap have given the most satisfactory results from the standpoints 

 of safeness to the trees and effectiveness against the psyllas. The 

 homemade oil-emulsion proved to be much less satisfactory as 



