2 MISC. PUBLICATION 5 0, U. S. DEPT. OF AGRICULTURE 



The proper identification of fleas forms a sound basis for disease 

 prevention and flea control. This publication, prepared primarily as a 

 taxonomic revision, will help those called upon to identify the species 

 of these insects and recommend control procedures. Full descrip- 

 tions are given of the genera and higher groups, accompanied in 

 most instances by figures. For species, subspecies, and varieties 

 formal descriptions are avoided, but data have usually been supplied 

 for each as follows: Indication of synonymy, name of tj^pe host, 

 type locality, statement relative to range, and remarks upon identifica- 

 tion characteristics, nature of original description, references to 

 figures, published notes on biology or economic importance, and 

 redescriptions. 



In the preparation of this work the literature has been reviewed up 

 to the end of 1939, and in addition data from those papers that were 

 published before October 1, 1940, are included, if the material upon 

 which they were based was available for study. 



Although the fleas of North America have probably been studied 

 more extensively than those of any other continent, only two large and 

 comprehensive papers dealing with them have been published. One of 

 these was by Baker (J/,) 2 in 1904, revising all the American fleas, and 

 the other by I. Fox (25) in 1940, revising the fleas of the eastern part 

 of the United States. Thus an up-to-date treatment of all North 

 American fleas is in order. In a limited way a review of the species 

 of this continent is here presented, it being based largely upon the 

 extensive collections of the United States National Museum and of 

 the Bureau of Entomology and Plant Quarantine of the United States 

 Department of Agriculture. 



Since taxonomic categories are concepts, any extensive use of them 

 should be preceded by definitions or a statement explaining their limi- 

 tations. The difference between the genus and the subgenus, as these 

 two categories are here used^lies in the nature of the characters em- 

 ployed. Characters which, from a morphological standpoint, would 

 be considered as of only specific importance, if occurring in all species 

 of a small natural group, are here regarded as being of subgeneric 

 value. Characters of the terminalia of both sexes, if they have to do 

 with the presence or absence of a structure or a change in the relation- 

 ship of one structure to another, are regarded as supplemental generic 

 characters, or in certain cases these sex characters alone may constitute 

 the distinguishing characters of a subgenus. In other words, all first 

 groupings of related species based exclusively on sex characters con- 

 stitute subgenera. If, however, these sex characters are correlated 

 with one or more other characters, even though the latter are rather 

 insignificant, the group of so-characterized species is regarded under 

 most conditions as a genus. 



The differences implied between a subspecies and a variety, as the 

 two terms are here employed, have to do not so much with the con- 

 spicuousness or morphological importance of the characters used as 

 with their variation. Minor characters which are continuously vari- 

 able, such as coloration (amount of pigmentation), length of certain 

 setae, or the shape of some part of the terminalia, are considered of 

 varietal importance if the variations are correlated with geographical 



2 Italic numbers in parentheses refer to Literature Cited, p. 124. 



