INTRODUCTORY NOTE. 



In 1888 there was published under the Division of Entomology, as 

 Bulletin No. 19, "An enumeration of the published synopses, cata- 

 logues, and lists of North American insects," etc. This bulletin has 

 served a very useful purpose in enabling a full answer to inquiries 

 regarding the works most useful in the determination of our native 

 insects and also 4-egarding the most useful general works of reference. 

 Since the publication of Bulletin No. 19, however, there has been very 

 great activity in entomological work, and the bulletin is now well 

 behind the times. Anyone who has ever taken up the study of ento- 

 mology realizes the difficulty of securing a comprehensive review of 

 the literature, even of a small group, while to secure publications 

 which will enable him to determine the known species in most of the 

 groups is more or less difficult. In fact, it is difficult to learn even 

 the title of such papers and where to procure them. This latter diffi- 

 culty will be solved by the present bulletin. Mr. Banks has not com- 

 piled a complete bibliography of the literature of North American 

 insects, but has given briefly the references to such works and papers 

 as are most useful for the identification of our insects. The old list 

 has been added to greatly, and in fact the number of papers cited is 

 almost double that of the previous bulletin. 



L. O. H. 



