INTRODUCTION 



Twenty years ago all the large European Lasiocampids were in- 

 cluded in the two genera Lasiocampa and Bomby.v, following the cat- 

 alogue of Staudinger and Woche published in 1871. Today we have 

 in their place about a dozen genera: European entomologists have 

 recognized the necessity for separating such a heterogenous assem- 

 blage, and we now find in the text-books that Bomby.v has been en- 

 tirely removed, Lasiocampa greatly restricted, and such genera as 

 Cosmotrichc, Epicnaptcra, Gastropacha, Dendrolimus and Macrothy- 

 lacia, genera mostly erected by those excellent entomologists of the 

 early part of the 19th century, revived and given their proper place 

 in the system. 



A somewhat similar state of affairs to that above referred to ex- 

 ists at the present time in regard to our large N. American Lasio- 

 campid moths. The species occur only in the extreme southwest of 

 the United States and in Mexico, and in consequence have been until 

 recently but little known and even in the largest collections but poorly 

 represented. Our United States species have all been grouped under 

 the one genus Glovcria Pack, in the latest published list (Bull. U. S. 

 Nat. Mus., No. 52, 1902), whilst the Mexican forms have been indif- 

 ferently placed under such genera as Dendrolimus Germ., Eutricha 

 Hbn., Lcbeda Wlk., Metanastria Hbn., and Macrothylacia Ramb., 

 genera which have either no true status or have been erected for 

 European and Asiatic species not congeneric with our N. American 

 forms. Our original intention had been to confine our attention to the 

 species occuring north of Mexico, basing our remarks and conclusions 

 on the material contained in Dr. Barnes' collection, which is especially 

 strong in this group. Dr. Dyar, however, very kindly placed a num- 

 ber of Mexican species from the U. S. National Museum at our dis- 

 posal, suggesting that we attempt to make our review as general as 

 possible. We have therefore done this, but must confess to possessing 

 none of that feeling of certainty concerning many of the Mexican 

 species which we rightly or wrongly possess concerning the Arizona 

 forms ; long series of both sexes from various localities will be neces- 

 sary in many instances to determine the range of variation, always 

 considerable in the large Lasiocampids, and until these are forthcom- 



