42 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



Mr. E. W. Rust and Mr. Dwight Isely were elected to active 

 membership and Mr. A. F. Satterthwaite to corresponding 

 membership. 



The following officers were elected for the ensuing year: Presi- 

 dent, Mr. A. N. Caudell; 1st Vice-president, Mr. C. R. Ely; 

 2nd Vice-president, Mr. E. R. Sasscer; Corresponding Secretary- 

 Treasurer, Mr. S. A. Rohwer; Recording Secretary, Mr. A. B. 

 Gahan; Editor, Mr. J. C. Crawford; additional members of the 

 Executive Committee, Mr. Schwarz, Mr. Quaintance and Mr. 

 Marlatt. 



To represent the Society as a Vice-president of the Washington 

 Academy of Science, Mr. W. D. Hunter. 



The following papers were read: 



ON THE OCCURRENCE OF AN INTERMEDIATE IN 

 APHIS POMI DeGEER. 



(With Plate X ) 

 BY W. F. TURNER AND A. C. BAKER. 



The family Aphididse presents many problems for the atten- 

 tion of the student of bionomics which are presented by no 

 other similar group of insects. This, for the reason that the 

 majority of the insects composing this group confine their feed- 

 ing to definite host plants; that many of them cannot, or at least, 

 ordinarily do not complete a year's cycle without the aid of two 

 different species, and usually genera or even families of host 

 plants; that several distinct forms of adults occur during one 

 year's cycle; and finally that two or even three modes of repro- 

 duction may occur in the same period. 



In the present paper we are concerned only with the last two 

 items. In general, the adult forms may be classified in one of 

 the following groups: First, the stem-mother, which hatches from 

 a hibernating egg, or less often, is born in the fall and itself 

 hibernates. It is parthenogenetic and may produce either living 

 young or eggs. Second, the summer forms, either alate or apter- 

 ous. Here any one of a variety of conditions may exist. The 

 alate forms may occur promiscuously throughout the summer, 

 or they may be confined to certain generations. In the latter 

 event they may occupy those generations in which they occur 

 to the exclusion of the apterous form, or may share the goner- 



