April, '12] PARROTT AND HODGKISS: PEAR PSYLLA 193 



W. D. Hunter: I think that the present plan of control of insects 

 in tobacco does not concern itself with X-rays at all, but with a high 

 frequency current. The man referred to carried on numerous exper- 

 iments in Philadelphia, first with X-rays but later Avith high fre- 

 quency currents. One of my associates provided numerous tests 

 with the X-ray apparatus. It was found that the results were not 

 satisfactory. At that time the experiments turned to high frequency 

 currents. 



President F. L. Washburn: The next paper on the programme 

 is by Mr. Swenk, of Nebraska, on ''The More Important Injurious 

 Insects in 1911 in Nebraska." 



THE MORE IMPORTANT INSECTS IN 191 1 IN NEBRASKA 



By Myron H. Sw^xk, Lincoln, Nebr. 

 (Papej- not received) 



The following papers were read by title and made a part of the 

 proceedings : 



THE SUSCEPTIBILITY OF ADULTS AND EGGS OF PEAR 

 PSYLLA TO SPRAYING MIXTURES 



By P. J. Parrott and H. E. Hodgkiss 



(Abstract) 



In summarizing briefly this paper the chief points presented are, — 

 (1), that the emergence of adults from winter quarters, deposition of 

 eggs and migration of larvae occur with very little intermingling at 

 distinct time periods and are, to a large degree, coincident respectively 

 with certain life events of the pear tree, as the swelling of the buds, 

 development of the blossom clusters, and opening of blossoms; (2), 

 that the psylla in each of its life stages is sensitive to certain spraying 

 mixtures. Experiments in 1910 indicated the possiblitity of protect- 

 ing pear orchards by a single treatment to kill either the adults, or 

 eggs, or nymphs. 



The presence of the psylla in destructive numbers in 1911 in the 

 leading pear growing sections of western New York afforded exception- 

 al opportunities for a large series of tests to demonstrate, under ordi- 

 nary orchard conditions, the susceptibility of hibernating "flies," 

 eggs and nymphs to various mixtures. Quite a number of growers 

 freed their orchards of the pest by spraying for the "flies" with miscible 

 oils, home-made emulsions or commercial nicotine preparations. The 



