PERGANDE — NORTH AMERICAN PHYLLOXERIN^ 185 



NORTH AMERICAN PHYLLOXERIN/E 

 AFFECTINQ HICORIA (CARYA) AND OTHER TREES. 



BY THEO. PERGANDE. 



INTRODUCTION. 



In the course of my studies of the Aphides of the United States, 

 occupying more or less of my time during the past twenty-five 

 years, I became much interested in our native Phylloxerinae as 

 well as the curious galls or deformations produced by them, and 

 have consequently made a few interesting observations, detailed 

 in the present paper. 



Early in the spring of 1889 the late Dr. C. V. Riley received a 

 letter from Dr. Dreyfus, Wiesbaden, Germany, announcing his 

 intention of monographing the Chermesinse of the world, outlin- 

 ing his plan and progress of the work, accompanied by examples 

 of the nature of the illustrations prepared for it, and urging Prof. 

 Riley to assist him in this work with notes and figures of the 

 species of Phylloxerinae occurring in North America on our native 

 hickory trees. 



Dr. Riley, at the time of the receipt of this communication, was 

 in Paris, acting as the representative of the Secretary of Agricul- 

 ture in connection with the installation of the American agricul- 

 tural exhibit at the Universal Exposition of 1889, charged with 

 the duties of Assistant Commissioner in Group 8. It was, there- 

 fore, out of the question for him to undertake the work himself, 

 as desired by Dr. Dreyfus, and he directed the writer to draw up 

 descriptions of all of the known and new species and to prepare 

 the necessary drawings for the contemplated work. This work 

 was at once taken up energetically and thoroughly. 



In compliance with this request I restudied, as far as possible, 

 all the previously described species, of which, fortunately, many 



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