186 UNITED STATES NATIONAL MUSEUM BULLETIN 2 76 



as in figs. 390, 392, and 393). (3) The darker males similar to those in 

 figures 291 and 295 (most males of i. incurvum are lighter as in figs. 292, 

 294, 297, and 298). Neumoegen's aztecum is regarded as conspecific 

 with incurvum because of these similarities, as well as similarities between 

 adult females and preferred hosts. It is regarded as a subspecies because 

 of the differences in some life stages between it and the majority of 

 specimens of i. incurvum found in Arizona, and because of the almost 

 total lack of specimens or data from the large area lying between Mexico 

 City and the United States border. 



The only specimens available from this area (except for a single male 

 from Chihuahua) are a group of 64 adults, 1 1 larvae, and 3 egg masses 

 in the Canadian National Collection collected 6-10 miles west of El 

 Salto, Durango, on ocean spray {Holodiscus sp.), willow, and trembling 

 aspen. The adults are dark like those from Mexico City, and the larvae 

 are very similar to larvae from the Mexico City area. The ^gg masses 

 are covered with very dark spumaline containing no specks and cocoons 

 have a whitish powder similar to that of incurvum cocoons from all areas. 

 In every respect these specimens are more similar to specimens from 

 the Mexico City area than most specimens from Arizona, so they are 

 regarded as M. incurvum aztecum. Many more reared collections from 

 Mexico are needed. 



Adult Malacosoma from the vicinity of Mexico City can be segregated 

 into a dark brownish group described as Clisiocampa azteca (figs. 287 

 and 289) by Neumoegen in 1893 (including uniform brown specimens 

 called the variety unicolor by Hoffman, but apparently never published), 

 and a light yellowish group described by Dyar in 1907 as Clisiocampa 

 luteimargo (figs. 285 and 288). Both male and female luteimargo are 

 identical to aztecum in every respect except color. Dyar indicated in the 

 original description of luteimargo that it occurred with aztecum, and 

 there is a note on one specimen of luteimargo in the USNM indicating 

 that specimens like luteimargo make up about 2 percent of the specimens 

 collected with typical aztecum. 



Ancona (1930) regarded luteimargo as a variety oi aztecum. He examined 

 280 adult specimens (apparently reared) and found the following 

 percentages of color phases : Uniform light brown (variety unicolor) — 8 

 percent; dark brown with a blackish band separated from the external 

 margin of the forev>^ing by a narrow lighter line (apparently similar to 

 fig. 286) — 54 percent; lighter brown with two whitish lines on the 

 forewings (similar to "typical" aztecum, figs. 287 and 289) — 33 percent; 

 yellowish specimens with a dark band — 4 percent; yellowish specimens 

 with dark lines (similar to luteimargo, figs. 285 and 288) — 2.5 percent. 



He also noted that the variety unicolor had black eyes, the variety 

 luteimargo had pale yellowish eyes, and the most abundant forms had 



