124 UNITED STATES NATIONAL MUSEUM BULLETIN 2 76 



Malacosoma califorjiicwn (Packard). Langslon, 1957, p. 6 (in part, Guerneville, 



Healdsburg and vicinity). 

 Malacosoma sp., Langston, 1957, p. 7. 

 Malacosoma pluviale recenseo Dyar, sensu Langston, 1957, pp. 8-9 (in part, Modoc 



Co. population E. of Sierra Nevada-Cascade divide in Calif.). 

 Rocky Mountain tent caterpillar, Clark, 1958, pp. 132-139. 

 Malacosoma pluviale (Dyar), sensu Steinhaus, 1962, p. 433 (in part, Nos. 1046, 



1047, 1049, 1051, 1105, 1599). 



Malacosoma californicum with its subspecies is the most variable North 

 American tent caterpillar. Variation in the color pattern ranges from 

 practically none in some populations to others in which several 

 conspicuously different color patterns can be obtained by rearing 

 larvae from a single isolated tent, which presumably hatched from a 

 single egg mass. Any attempt to include in a description the many 

 variations in pattern and color found in this species throughout its 

 range is doomed to failure because of this. Therefore, the following 

 description is quite general, and more detailed descriptions are given 

 for the recognized subspecies. The important fact to remember is not 

 that the recognized subspecies may be difficult to distinguish in some 

 life stages, but that they are subpopulations of a single species, M. 

 californicum^ rather than several different species as has been believed 

 up to the present time. 



ADULT MALES (males in figs. 176-284 except figs. 206-208).— 

 Color varying from dark reddish-brown to yellow or gray, and many 

 intermediate shades. Lines on forewings almost always present, appear- 

 ing lighter or darker than the ground color, but if darker, usually 

 bordered by a narrow lighter area. (For a discussion of the components 

 of the wing color pattern see the introductory section on adults, 

 page 34.) Specimens from the Great Basin, Mojave Desert, and 

 southern Rocky Mountains often have indentations along the veins 

 which may meet to cut off "islands" as in figure 270. These in- 

 dentations are greatest along Cu2. (Specimens of americanum, tigris, 

 constrictum and disstria never have indentations along the veins.) Hind- 

 wing lighter or darker than forewing, often about same color, and 

 sometimes with a contrasting band. Lower surface of both forewings 

 and hindwings usually somewhat darker than ground color of upper 

 surface, and both wings usually crossed ventrally by a single contrast- 

 ing line. Epiphysis usually small, about the size of second segment of 

 foretarsus, but rarely larger. 



MALE TERMINALIA. — Posterior edge of seventh sternite (figs. 

 64-71) not distinctive, varying from heavily sclerotized and with 

 distinct "teeth" to practically unsclerotized and smooth; often with a 



