PREFACE 



IT IS now nearly thirty years since "A Manual for the Study of 

 Insects," in the preparation of which I was aided by Mrs. Corn- 

 stock, was published. The great advances in the science of ento- 

 mology during this period have made a revision of that work desirable. 

 In the revision of the "Manual" so many changes and additions have 

 been found necessary that the result is a book differing greatly from 

 the original work; for this reason, it is published under a different 

 title. The title selected is that of an earlier work, an "Introduction 

 to Entomology" published in 1888 and long out of print. 



Part I of the present volume was published separately in 19 19, in 

 order that it might be available for the use of classes in insect mor- 

 phology and also that an opportunity might be offered for the sugges- 

 tion of desirable changes to be made before the incorporation of it in 

 the completed work. Such suggestions have been received, with the 

 result that some very important changes have been made in the text. 

 In the preparation of this work I have received much help from 

 my colleagues in the entomological department of Cornell University, 

 for which I wish to make grateful acknowledgment, and especially 

 to Dr. J. G. Needham for aid in the study of wing-venation, to Dr. 

 O. A. Johannsen for help in the preparation of the chapter on the 

 Diptera, to Dr. W. T. M. Forbes for help in the preparation of the 

 chapter on the Lepidoptera, to Dr. J. C. Bradley for help in the prep- 

 aration of the chapter on the Hymenoptera, and to Dr. J. T. Lloyd 

 for the use of his figures of the cases of caddice worms. 



From the published works of Professors Herrick, Crosby and 

 Slingerland, Crosby and Leonard, Sanderson, and Matheson I have 

 gleaned much information; references to these and to the more im- 

 portant of the other sources from which material has been drawn are 

 indicated in the text and in the bibliography at the end of the volume. 

 References to the bibliography are made in the text by citing the 

 name of the author and the year in which the paper quoted was 

 published. 



The wood cuts used in the text were engraved from nature by 

 Mrs. Anna B. Comstock for our joint work, "A Manual for the Study 

 of Insects." The other original figures and the copies of published 

 figures were drawn by Miss Anna C. Stryke, Miss Ellen Edmonson, 

 Miss Mary Mekeel, Mr. Albert Force, Mrs. Louise Nash, and Miss 

 E. L. Keyes. I am deeply indebted to each of these artists for the 

 painstaking care shown in their work. 



