PREFACE 



XiyHEN a few years ago I published "The Butterfly Book," I 

 * v stated in the preface to that volume that I would follow it 

 by the preparation of a similar work upon the moths of the United 

 States and Canada, provided the reception given that venture 

 should seem to justify me in so doing. "The Butterfly Book" 

 was very favorably received, and not only I, but my publishers, 

 have been besieged with letters from all parts of the continent, 

 urging the fulfillment of the provisional promise made by me in 

 1898. A prompt compliance with these requests has, however, 

 unfortunately been impossible, owing to the fact that my official 

 duties, which are numerous and exacting, prevent me from devot- 

 ing any but the evening hours to the work of literary composition. 

 In addition to the difficulties arising from this source, there were 

 other and even greater difficulties which presented themselves. 

 The species of moths known to occur in the United States and 

 Canada vastly exceed in number the species of butterflies found 

 within the same limits. While it was possible to bring together 

 brief descriptions and numerous illustrations of the majority of the 

 species of butterflies found in the region, it became evident at the 

 outset that in dealing with the moths it would be necessary to 

 resort to a different method. It became plain that a process of 

 selection would have to be followed, if the volume were to be 

 kept within proper limits as to size and cost. It would have been 

 comparatively easy to have selected from the abundant material 

 at my command a series of the more showy insects, and to have 

 illustrated these, but as it is the purpose of the series of the books 

 of which "The Moth Book" is one to provide in reasonably 

 compact form manuals which will with tolerable completeness 

 cover the whole field, the plan had to be materially altered. In- 

 stead, therefore, of attempting to briefly describe and figure all 

 the thousands of species of moths which have been ascertained to 



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