PREFACE 
'Vl/’HEN a few years ago I published “The Butterfly Book," I 
^ 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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