RE\7SI0N MALACOSOIVIA HUBNER IN NORTH AMERICA 173 



from Texas, and only a single questionable male from Silver City, New 

 Mexico, has been seen. 



No tents were found on cottonwoods in the Imperial Valley of 

 California either, although conditions appear to be suitable there at 

 the present time, even though they may not have been before irrigation 

 and the planting of cottonwoods. A single male in the United States 

 National Museum from the Barnes Collection labeled "Palm Springs, 

 Riverside Co., Calif., 1-7 April," and two females from the O. Buchholz 

 Collection in the American Museum of Natural History labeled "Bishop, 

 Cal., 6-14-37, E. C. Johnston" and "Cal., IV-27" are the only speci- 

 mens which are supposed to be from California. All three of these 

 specimens are similar to those found near Phoenix, Arizona. If the data 

 on these specimens are reliable, it seems most likely that they were 

 carried into California as larvae or cocoons, since we are not aware of 

 any reports of tent caterpillars on cottonwoods in California. 



ECONOMIC IMPORTANCE.— M. incurvum (including its sub- 

 species) has caused heavy defoliation of cottonwoods and willows in 

 Utah and Arizona, and defoliation of willows in the vicinity of Mexico 

 City. Nevertheless, it must be regarded as more of a nuisance than a 

 serious pest since these hosts usually are classified as ornamentals, or 

 even undesirables if they grow along irrigation canals and use valuable 

 water. No important defoliation has been reported on other hosts. 



Malacosoma incurvum incurvum (Henry Edwards) 



Clisiocampa incurva Henry Edwards, 1882, p. 125. — Neumoegen and Dyar, 



1893, p. 30.— Dyar, 1893, p. 43. 

 Clisiocampa incurva var. comtrictina Neumoegen and Dyar, 1893, p. 30. Type: 



Holotype, male, Arizona, United States National Museum Type No. 33662. 

 Clisiocampa Jragilis Stretch, sensu Neumoegen and Dyar, 1894, p. 155 (in part). 

 Clisiocampa Jragilis var. constrictina Neumoegen and Dyar, Neumoegen and 



Dyar, 1894, p. 155 (in part). 

 Malacosoma Jragilis incurva (Henry Edwards), Dyar, 1903, p. 262 (in part.) — 



Dyar, 1928, p. 623, pi. 86i (in part) .—Collier, 1936, p. 1 14.— McDunnough, 



1938, p. 138. 

 Malacosoma Jragilis constrictina (Neumoegen and Dyar), Dyar, 1903, p. 262 (in 



part.)— Dyar, 1928, p. 623 (in part). 

 Malacosoma constricta (Stretch), sensu Essig, 1926, p. 697 (in part, Arizona 



population). — sensu Keen, 1952, p. 95 (in part, Arizona population). 

 Malacosoma Jragilis azteca ab. constrictina (Neiunoegen and Dyar), Collier, 1936, 



p. 114. 

 Malacosoma Jragilis incurva form constrictina (Neumoegen and Dyar), McDun- 

 nough, 1938, p. 138. 

 Malacosoma constrictum (Stretch), sensu Langston, 1957, pp. 9-10 (in part, 



Arizona population). 



