REVISION MALACOSOMA HUBNER IN NORTH AMERICA 127 



gray-white, depending on the area. The only species which lay similar 

 clasping egg masses are americanum and incur mm. See the descriptions of 

 their egg masses for the best way to distinguish them (pages 1 14 and 1 72). 



TENTS. — Tents are relatively large, and similar to those of americanum 

 and incurvum from which they cannot be separated. 



COCOONS. — Cocoons are loosely to compactly constructed, often 

 with an outer envelope of silk, especially in the more northern popula- 

 tions. Cocoons usually are dusted with a yellowish powder in northern 

 and far western populations. The powder is usually whiter in the more 

 southern populations, especially in the Mojave Desert area. 



FOOD PLANTS. — The number of shrubs and trees on which this 

 species will oviposit is quite large, to say nothing of those on which it 

 will feed. See the collection data in Appendix I for the host plants on 

 which calif ornicum and its subspecies were collected during this study. 



TYPE. — See M. calif ornicum calif ornicum (page 141). 



DISTRIBUTION. — Malacosoma calif ornicum and its subspecies occur 

 tliroughout most of western North America wherever suitable host 

 plants grow (figs. 2, 3). The subspecies calif ornicum pluviale extends 

 eastward through Canada almost to the Atlantic Coast. Its northern 

 distributional limits are not definitely known, but it may extend as 

 far north as suitable hosts grow. No specimens from Alaska have been 

 seen, but c. pluviale probably occurs there, at least in the southeastern 

 coastal region. Its southern distributional limit has not been established, 

 but it should occur in many parts of the Mexican plateau. 



Few specimens of calif ornicum from Southern California have been 

 seen (excluding M. calif ornicum fragile which occurs in the desert areas). 

 Specimens from the following six localities in Southern California have 

 been plotted in figure 2: Lebec (Kern Co.), Temecula (Riverside Co.), 

 Bouquet Canyon (Los Angeles Co.), El Cajon and Upland (San 

 Bernardino Co.), and Tub. Canyon, Borrego (San Diego Co.). All of 

 these records are single adults except for three from Upland and two 

 from Tub. Canyon, Borrego. No preserved larvae have been seen from 

 Southern California, and no colonies could be located in the field 

 despite extensive surveys in both 1960 and 1961. 



Some of these records may be due to errors in labeling, but it seems 

 unlikely that all of them are. Nevertheless, it is doubtful if these nine 

 specimens were taken from populations which are native to Southern 

 California. The most likely explanation for them is that they either 

 were brought there as cocoons on cars, freight, etc., or they were in- 

 troduced as egg masses on transplanted trees of various sorts, most 

 likely fruit trees. 



Climatic conditions in Southern California are quite different from 

 those in more northern areas, so northern forms of calif ornicum would 



