4 UNITED STATES NATIONAL MUSEUM BULLETIN 276 



can Museum of Natural History, the California Academy of Science, 

 Michigan State University, and the Canadian National Collection, 

 which also has a more complete collection of larvae and egg masses, 

 A nearly complete collection of all life stages has been deposited at 

 the U.S. National Museum. The University of Minnesota collection 

 contains specimens from all collections made. 



History of the Classification of Malacosoma in 

 North America 



Most species of North American Malacosoma were described prior to 

 1900, and most of them were described under the generic name Clisio- 

 campa Curtis 1828 before it was realized that Hiibner had proposed 

 Malacosoma in 1820. 



Currently, four species of Malacosoma generally are recognized in 

 Europe and North Africa (at least one of which extends across Asia 

 all the way to Japan), and two are described from northern India. 

 At the time this study was begun, ten species were recognized in North 

 America. The classification in North America has remained essentially 

 the same for the past 50 years, except that Freeman raised M. fragile 

 lutescens (Neumoegen and Dyar) to species rank in 1949. 



East of the 95th meridian (roughly a line drawn from the Manitoba- 

 Ontario border to Houston, Texas), the classification has been quite 

 clear-cut, since only two species, M. americanum (Fabricius), the 

 eastern tent caterpillar, and M. disstria Hiibner, the forest tent cater- 

 pillar, were recognized until 1937. In that year a third species, the 

 so-called western tent caterpillar, M. pluviale (Dyar), was recorded 

 from eastern Canada by Atwood (1943). These three species are quite 

 distinct, and usually there is no difficulty in distinguishing them. 



West of the 95th meridian, however, the situation is entirely diff'erent, 

 for many species, subspecies, forms, etc., were recognized when this 

 study was begun. Most of these were described from one or, at most, a 

 few specimens from a single locality, with little or no idea of the popula- 

 tions that occurred in areas between the type localities. Of course, 

 this is to be expected, since, in the period between 1850 and 1900 when 

 most of the species were described, the West still was being settled and 

 many areas were virtually inaccessible or inhospitable. 



During this period and up to the present, it had been recognized 

 widely that the adults were highly variable in color and pattern, and 

 that it was hazardous to describe a species in this genus without knowl- 

 edge of the larvae (which were believed to be relatively constant in 



