OF WASHINGTON, VOLUME XII, 1910. 179 



SOME SYNONYMY AND OTHER NOTES ON APHIDIINJE. 



BY A. B. GAHAN. 



[Contribution from the Entomological Laboratory <>1 thr Maryland Agricultural 



Experiment Station.] 



The writer has had the pleasure, through the kindness of 

 Mr. J. C. Crawford and Mr. H. L. Viereck, of examining all 

 the types of Aphidiiuae in the United States National Museum, 

 and through the courtesy of Rev. V. A. Huard, of the 

 Museum of Public Instruction, Quebec, also obtained the loan 

 of the Provancher types in that group. The study of these 

 types in conjunction with several large series of reared speci- 

 mens representing a number of different species and genera has 

 developed a few facts which it is hoped will help to straighten 

 out the difficulties in the classification of this important group 

 of parasites. It is for the purpose of calling attention to these 

 facts and to record some notes on the host relations of several 

 species, the hosts of which have been heretofore unknown, 

 that this paper is published. Incidentally, it will record also 

 the occurrence of four European species not hitherto credited 

 to our fauna. 



Most workers in this group have depended too largely upon 

 minute variations in color and the mistaken idea that the 

 number of antennal joints is always the same for the same sex of 

 any g-iven species. Dr. Ashmead, who described the majority 

 of the American species, gives some tables of species (Proc. 

 U. S. Nat. Mus., 1888), in which he depends very largely 

 upon differences in the number of antennal joints to distin- 

 guish species. More recent writers have proven that in the 

 genus Lysiphlebus t at least, there is considerable variation in 

 this respect. In rearings of large series of specimens repre- 

 senting the genera Aphidins, Lysiphlebus, and Diceretus the 

 writer has invariably found individuals more or less numerous 

 and representing both sexes, the number of whose antennal 

 joints was at variance with that given by Ashmead for the 

 species. After a careful study of several such series, supple- 

 mented by some breeding experiments from known parents 

 (mentioned in another connection farther on) it became ap- 

 parent that in the three genera mentioned we may expect to 

 find variation to the extent of two joints and usually three 

 joints for each sex in every species. Only rarely is a greater 

 variation found. The males, so far as is known, invariably 

 have more joints than the females, the number varying from 

 one to four. In no species have I found a difference of more 

 than five joints between the females having the greatest and 

 the males having the greatest number of joints. 



