Introduction 



By 



Karl V. Krombein, 



Paul D. Hurd, Jr., 



and 



David R. Smith 



Preparation and production of this third vol- 

 ume containing various indexes has been tre- 

 mendously facilitated and accelerated by 

 computer technology. Manipulation of the 

 data base already computerized for the catalog 

 itself (Volumes 1 and 2) enabled us to obtain a 

 listing of taxa in all hierarchies or data catego- 

 ries in numerical sequence. Page numbers 

 were punched by hand, entered into the com- 

 puter, and then separate programs were run 

 for each index resulting in the arrangement of 

 taxa in alphabetical sequence with pertinent 

 page references. The final step was the conver- 

 sion of the computerized data to a special 

 magnetic tape capable of driving the photo- 

 typesetting unit, the VideoComp 500 Photo 

 Composer, in the Government Printing Office. 



Numbers of Genera and Species 



The followdng tables are presented to answer 

 one of the most frequently posed questions 

 concerning a catalog— how many taxa? Table 

 1 gives the number of valid genera and species 

 of each family and higher category in America 

 north of Mexico. The taxa are arranged in 

 sequence as they appear in the catalog. Sub- 

 species and varieties of a polj^ypic species 

 listed as valid entities are counted as only one 

 species. For example, alba alba and alba rufa 



are counted as only one species. However, if 

 only one taxon of a pol5rtypic species occurs in 

 America north of Mexico, it is counted as a 

 species. Species listed in unplaced categories 

 are generally not included. Numbers in paren- 

 theses represent totals for categories above 

 family level. 



In Table 2 the superfamilies are arranged by 

 size according to number of species and per- 

 cent of the total species of Hymenoptera in 

 America north of Mexico. 



Table 1. Numbers of Hymenoptera taxa in America 

 North of Mexico 



vu 



