

103 



would expect from its great abundance last year, due, I think, to some 

 extent to tlie fact that the trees were coated with a sheet of ice for nearly 

 a week at one time during the winter when many of the hibernating 

 adults must have i^erished. This year the trees are infested, but not to 

 an alarming extent, and they are making a good growth; but, owing to 

 the great drain of last year, but few trees blossomed, and those which 

 did had not sufficient strength to develop the fruit. 



Mr. Osborn asked if the insect was not easily killed on the wing. 

 Mr. Slingerland stated in reply that he had understood that the adults 

 took wing as soon as any attempt was made to spray the trees ui^on 

 which they Avere located. In reply to a question of the southern limit 

 of the species in Kew York he stated that he had no information of its 

 occurrence farther south than Catskill Landing, on the Hudson River. 



Mr, Riley believed the author was correct in his identification of the 

 species, and in the conclusion that simulans was but a form of pyricola. 

 He also fully agreed with the statement made by the author in regard 

 to the effect of kerosene emulsion on the eggs of insects; that the pub- 

 lished statements as to its effect upon insect eggs were in many cases 

 hypothetical, and not based on actual experience, was but too mani- 

 fest. His own experiments have been largely confined to the eggs of 

 Aphididse which vary considerably in thickness of shell, but so far as 

 his observations went they would indicate that a strong kerosene emul- 

 sion, while not causing the eggs to shrivel at first, would in the end 

 destroy — i. e., prevent the hatching — of large numbers, especially where 

 the treatment was repeated. Experiments on the eggs of Aleyrodes on 

 the Orange gave similar results. He would call attention to two facts 

 which would, to some extent, explain the varying exi^erience in this 

 particular line; first, the difference in resisting power and thickness of 

 egg-covering; secondly, the character of the emulsion and the method 

 of its application. A stable emulsion, made according to the Hubbard 

 formula and applied in a very fine spray, would be much more effective 

 than an unstable emulsion applied in a coarser spray. The value of 

 the emulsion depended largely on the extent of the divisibility of the 

 oil globules in the menstruum or emulsifying agent ; where these par- 

 ticles were relatively large no amount of spraying would cause any of 

 the oil to adhere to a highly polished surface like that of most insect 

 eggs, whereas when the particles were microscoxncally minute and the 

 spraying very fine, the particles would be more ax^t to settle upon such 

 a surface. 



Mr. Lintner stated that in spraying for the Psylla, only the Cyclone 

 nozzle should be used, as it discharged the liquid in such a manner as 

 not to agitate the foliage, and thus disturb the insects, who were thus 

 drenched without warning. 



Mr. Smith said that he had been very successful with kerosene 

 emulsion in destroying the eggs of Piilvinaria innumeraMlis, and in 



