LETTER TO THE SECRETARY. 



Office of United States Geological and Geographical 



Survey of the Territories, 



Washington, March 1, 1876. 



Sir: In presenting to the public the present monograph by Dr. 

 Packard, I feel assured not only of the hearty approval of all entomologists, 

 but also of scientific men generally. 



I deem it one of the most important parts of the work of such surveys, 

 second. only to their chief object, to seize upon the opportunity of completing 

 such monographs as the present; otherwise, materials which individuals and 

 various expeditions have been collecting, may remain for years in private or 

 public museums, or perhaps be destroyed, without any systematic arrange- 

 ment ever having been made. But this is not the only and greatest benefit to 

 be derived from such monographs as the present: it is practically useful as an 

 assistant in the economic entomology of our country, as this memoir embraces 

 one of the most injurious groups of Lepidopterous insects. 



These monographs also enable those who are constructing elementary 

 works, for the use of our colleges and schools, to bring into harmony and 

 properly systematize the whole. In fact, so great is the want that is now 

 felt in this respect that I have been called upon to furnish a limited number 

 of copies to some of our Western institutions, to be used directly in instruct- 

 ing the more advanced classes. 



The time has come in this country when monographs, complete and 

 exhaustive in reference to the field embraced, are demanded ; and no more 

 important work can now be done in natural history than to bring out such 

 memoirs where the facts and material are sufficient. 



I therefore feel assured that not only scientists, but the entire educated 

 portion of our people, will give their hearty encouragement in this work. 

 Such publications are monuments which will, in years to come, point back 

 to the wisdom of the liberal policy adopted by Congress in aiding the prose- 

 cution of this Survey, and allowing it that latitude which enables it thus to 

 work up fully and exhaustively not only the immediate material obtained, 



