ICHNEUMONID^. 289 



A LIST OF THE ICHNEUMONIDiE OF NORTH AMERICA, 



with descriptions of new species. 



BY E. T. CRESSON. 

 PART I. 



The preparation, at this time, of a List of so extensive and difficult 

 a family of insects as the Ichneumonidj>3, cannot but be a very imper- 

 fect work; but as a beginning must be made sometime, there seems to 

 be no good reason why it should not be made now. The extensive 

 material contained in the Collection of the American Entomological 

 Society, together with the fine Collection of Mr. Edward Norton, 

 kindly loaned by that gentleman for the purposes of this List, war- 

 rant this attempt to catalogue the species, and shows that in the num- 

 ber of species, this Family is second to none, if not the largest, in any 

 Order of insects. The great variation in the coloring of many species, 

 especially of the genus Ichneumon^ render the separation of the spe- 

 cies often difficult and uncertain ; and there is no doubt whatever that 

 some of the species described here will eventually prove to be nothing 

 but varieties. Many species are known of one sex only ; in some cases 

 only males, in others only females, and occasionally one or the other 

 of them in plenty; this is owing to the dissimilarity between the 

 sexes, especially observable in the genera Ichnemnon and Crijptus. 



The classification of the genera adopted here, is much the same as 

 that given by Prof. Gravenhorst, in his Ichneumonologid EuropBea. 



At the end of each Part, the descriptions of species supposed to be 

 new, and notes on those already described, will be given. 



To save space, references to original descriptions of the species will 

 be omitted in this List. References to all the species described up to 

 the year 1862, have already been given in the Proceedings Ent. Soc. 

 Fhil, Vol. I, p. 205 — 211 ; those described since, will be found in 

 that and the subsequent volumes of the same work. After the name 

 of the species and its author, will follow the sex in which it is known 

 or described, and then the habitat. For the Eastern, Middle, South- 

 ern and Western States, the abbreviations E. S., M. S., S. S., and W. 

 S., are used when certain species have been found in many States. 

 The abbreviations of the various States will be understood without 

 further explanation. A — after the species indicates that it is unknown 

 to me ; a = denotes that the species, although known to me, is not re- 

 presented in the Collection of this Society. 



TRANS. AMER. ENT. SOC. (37) OCTOBER, 1867. 



