No. 2315. TRIBES OF ICHNEUMONINAE—CUSHMAN AND ROHWER. 385 



sions/ and, after removing the closely allied genus Banchus on a char- 

 acter subject to specific variation, he separates the genera belonging to 

 the Ichneumoninae as here defined from the other genera of the Ichneu- 

 monidae m much the same unsatisfactory manner as that of Ashmead, 

 and in many places only on secondary sexual characters. There are, 

 however, a few new characters, and the work has contributed some- 

 thing to render the Ichneumoninae of the limited region somewhat 

 better understood. 



CLASSIFICATION. 



In presenting this revision of the subfamily Ichneumoninae we do 

 not wish to be construed as expressing an opinion that it is a natural 

 group. The family Ichneumonidae is a group composed of elements 

 showing remarkable differences but at the same time extreme homo- 

 geneity. So true is the latter that the grouping into five universally 

 recognized subfamilies is, in our opinion, untenable. The published 

 keys for the separation of these five subfamilies leave the placing of a 

 species in its proper subfamily ahnost entirely to the imagination or 

 experience of the worker. On the other hand, the strict interpreta- 

 tion of such characters as these keys offer frequently leads even the 

 experienced taxonomist to entirely misplace an insect; and disagree- 

 ment among workers as to the allegiance of certain genera or groups 

 of genera is very frequent. The Plectiscini, Banchini, and Paniscini 

 are notable as bones of contention, while all of the subfamilies, notably 

 the Tryphoninae and Ophioninae, are aggregations of groups not at 

 aU closely allied but thrown together on such superficial characters 

 as compression or depression of abdomen, long or short ovipositor, 

 possession or lack of sternauli, shape, presence or absence of the 

 areolet, etc. Anyone who has studied the insects of this group in 

 an at all intensive manner knows that such characters as these 

 are valueless as used in the keys, and he also knows that in de- 

 termining species he places them in the subfamilies without regard 

 to the characters of the keys but entirely from his knowledge of 

 genera. 



The subfamily Ichneumoninae, as treated here, is practically the 

 same as the subfamily Pimplinae in the sense of Holmgren, Cresson, 

 Ashmead, and others, with a genus here and there rejected as not 

 referable to the subfamily. We have adopted this restriction of the 

 subfamily as a matter of convenience and in accordance with the 



J Since the above was written Viereck has (Proc. Biol. Soc. Wash., vol. 31, 1918, p. 69) elevated all of the 

 tribes of the Ichneumonoidea to subfamily rank for the very naive reason, "to avoid confusion in referring 

 to groups of genera by word of mouth." In Ent. News, vol. 31, 1920, p. 16, he makes a family for the genera 

 Labena Cresson, Apechoneura Kreichbaumer, and Psiloparia, new genus. The value of this grouping has 

 been discussed by Cushman, Proc. Ent. Soc. Wash., vol. 22, no. 4, 1920. 



144.382— 20— Proc.N.M.vol.57 25 



