VI INTRODUCTION 



probably incorrect. We take responsibility for the determination 

 of the parasites, but not of the hosts. The nomenclature of the hosts 

 has been brought into conformity with recent usage, with the assistance 

 of specialists in the U. S. National Museum and the U. S. Department 

 of Agriculture. 



In discussing the seasonal distribution of a species we have usually 

 disregarded the dates on the pin labels of reared specimens because 

 many of these emerged in an indoors climate, out of their natural 

 season. 



The morphology of the ovipositor tip is often useful in the taxonomy 

 if these insects, so we have provided a figure (329, i) explaining its 

 terminology. 



Other students of ichneumon flies have been helpful in supplying 

 certain bits of information or assistance, comparing specimens with 

 types, or discussing some of the taxonomic problems with us. Miss 

 Luella Walkley of the U. S. Department of Agriculture, Mr. J. F. 

 Perkins of the British Museum (Natural History), Mr. G. Stuart 

 Walley of the Canadian Department of Agriculture, Prof. Toichi 

 Uchida of Hokkaido University, Mr. Gerd Heinrich of Dryden, 

 Maine, and Mr. R. R. Dreisbach of Dow Chemical Company are 

 among these. Mr. Pei kins' special knowledge of the family has made 

 his help valuable. Mr. Walley has placed at our disposal the extensive 

 locality and host information assembled by the Canadian Department 

 of Agriculture. Mr. Dreisbach has been particularly helpful in 

 collecting specimens for this study and being always ready with 

 friendly encouragement. The thorough representation of the State 

 of Michigan in the distributional data is the result of his efforts. 



In a work that attempts to bring together and use all available 

 information, it is essential to have the cooperation of the scientists 

 and institutions which have been responsible for the gathering of 

 the information and its conservation in accessible form. In the case 

 of this paper the assistance from all sources has been unfailing. 

 Curators of North American collections have lent the specimens under 

 their care, and individuals and institutions the world over have given 

 access to type specimens, or in some cases have sent them through the 

 mails for study. In connection with this paper we have seen or 

 reexamined t3^pes in the museums in Philadelphia, Washington, 

 Ottawa, Quebec, Urbana, New Haven, Cambridge, Ithaca, London, 

 Oxford, Brussels, Tervuren, Leiden, Amsterdam, Copenhagen, Lund, 

 Stockhold, Helsinki, Leningrad, Warsaw, Wroclaw, Berlin, Berlin- 

 Friedrichshagen, Halle an der Salle, Munich, Vienna, Budapest, Turin, 

 Genoa, Paris, Sapporo, and Taipeh. To the curators of all of these 

 we wish to express our appreciation. Their cooperation has permitted 

 the use of first-hand information for most of the nomenclatural 

 decisions. 



