218 BEUTENMULLER, MONOGRAPH OF THE SESIIDvE. 



the perfect insects are rarely found, and several years must elapse before the 

 species of his own district comes into the hands of a collector. They also 

 soon lose their scales through flight, and when pinned become covered with 

 grease, and important characters are often lost ; consequently considerable at- 

 tention must be given to the condition of the specimens before describing or 

 naming them. My studies of this difficult group of moths have been mainly 

 based upon the extensive material contained in the well-known Hy. Edwards 

 collection, which is now the property of the American Museum of Natural His- 

 tory. The Museum collection contains, with the exception of eight, all the 

 known species of Sesiidae found in America, north of Mexico. With the aid of 

 the types and material which have been submitted to me for examination, I have 

 been enabled to recognize all the known species occurring in this country, except 

 the following, the types of which, as far as I can ascertain, have been destroyed, 

 and the descriptions of them are too vague for their determination : Sesia 

 nomadcepenms, S. bibionipennis, S. anthraciformis, and S. chrysidipennis. The 

 last is probably the same as S. mellinipennis. 



The descriptions of the species in the following pages have in nearly all in- 

 stances been taken from fresh material, and the main object of the present 

 monograph is to place on record, in a permanent form, with colored figures, all 

 the species of Sesiidae of our fauna. It has also been my aim to make the paper 

 as complete as possible by adding the descriptions of the larvae and the food- 

 habits. It has not been possible to carry out this ideal to any extent, as the in- 

 formation in this respect is still very fragmentary and many years must elapse 

 before we shall be enlightened on this subject. It, therefore, has been deemed 

 best not to wait, but to bring forth the information we now possess in as 

 condensed and at the same time luminous a form as possible. 



In advance of the present monograph I have published from time to time a 

 series of papers containing the results of my studies of this family of moths, and 

 I believe that the species and genera found in this country are now fairly well 

 known. Nothing, however, has hitherto been published on the literature of the 

 family, except a few references given by me in the papers alluded to above, and 

 a few given by other writers. In view of this fact, I began, some time since, a 

 systematic investigation of the literature of the subject, and to my surprise 

 found before me a task of no small magnitude. Little did I suspect when I be- 

 gan that the work was almost endless, especially as regards the species con- 

 sidered of economic importance, and the two European species {/Egeria 

 apiformis and Sesia tipuiiformis) found also in this country. The literature 

 of these species is very extensive and the deficiencies of the present work relate 

 mainly to these, but I believe that the titles here presented cover nearly every 

 point of technical importance. All the titles were taken by me, except when 

 marked " not seen." These were obtained either from Dr. M. V. Slingerland or 

 have been quoted from the < Bibliography of the more Important Contributions 



