VI PREFACE 



Mrs. G. W. Peckham of Milwaukee, Wis.; Dr. William Trelease, 

 Director of the Missouri Botanical Garden; Dr. Henry Skinner, as 

 editor of "Entomological News;" and the editors of "The American 

 Naturalist." 



Acknowledgments are further due to the Boston Society of Natural 

 History, the American Philosophical Society and the Academy of 

 Science of St. Louis. 



Courteous permission to use certain figures was given also by The 

 Macmillan Co.; Henry Holt & Co.; Ginn & Co.; Prof. Carl Chun of 

 Leipzig; F. Diimmler of Berlin, publisher of Kolbe's Einfuhrung; and 

 Gustav Fischer of Jena, publisher of Hertwig's Lehrbuch and Lang's 

 Lehrbuch. 



The first edition, which was translated into Japanese by Professors 

 Miyake and Uchida, has had a large sale in Japan. 



The second edition contained much new matter, particularly a 

 chapter on the transmission of diseases by insects. 



This third edition has been brought up to date by the addition of a 

 great deal of new material, including a few new illustrations. Some two 

 hundred and fifty titles have been added to the bibliography but, to 

 accommodate these, it was necessary to discontinue other titles of less 

 importance. 



A new chapter, on insect ecology, is given. This ought to prove 

 useful, as the literature of the subject is scattered, and there has been 

 no similar comprehensive treatment of ecology from the viewpoint of 

 the entomologist. 



In the preparation of this chapter the author has been fortunate in 

 having the expert advice of Professor V. E. Shelf ord, of the University 

 of Illinois; who is not responsible, however, for any possible short- 

 comings in the chapter. 



The following scientific men also have gladly assisted by giving 

 desired information: Dr. L. 0. Howard, chief of the Bureau of Ento- 

 mology; Mr. A. F. Burgess, of the Bureau of Entomology; Prof. J. H. 

 Comstock, Cornell University; Prof. A. F. Shull, University of Michi- 

 gan; Mr. Nathan Banks, Museum of Comparative Zoology, Cambridge, 

 Mass.; Mr. Charles Macnamara, Arnprior, Ontario, Canada; Professor 

 A. O. Weese, University of New Mexico; Dr. C. P. Alexander, Mr; W. P. 

 Flint and Dr. H. Yuasa, of the Illinois State Natural History Survey; 

 Professor A. D. MacGillivray and Dr. R. D. Glasgow, of the Univer- 

 sity of Illinois. 



Permission to use the map for Plate V. was courteously given by 

 Dr. B. E. Livingston and the Carnegie Institution of Washington. 



