110 UNITED STATES NATIONAL MUSEUM BULLETIN 2 76 



were collected at light. In another collection made 10 miles west of 

 El Salto, Durango, Mexico, in 1964 by the Canadian National Col- 

 lections expedition 48 males and no females were collected. None of the 

 other North American species shows such an extreme difference 

 between numbers of males and females collected as adults. No explana- 

 tion for this difference in behavior of tigris females is known, but they 

 may not be attracted to light as strongly as females of other species. 

 In any event, it is a difference in behavior that must be taken into 

 account, if, for example, population estimates were to be made from 

 light trap counts. 



Normally colored larvae collected in Real County, Texas, in 1961 

 (Coll. No. 226), and reared to adults produced a total of 43 moths, all 

 normally colored (figs. 1 74 and 1 75) except for 3 males and 4 females 

 which were pale, straw-yellow, and had only very faint markings 

 (figs. 171, 172). These individuals are as large as the normally colored 

 moths and appear to be normal in every other respect. (All adults 

 from this collection were slightly smaller than normal moths, such as 

 figure 169, owing to disease and poor quality of the foliage fed to 

 them.) Some larvae from this collection died from disease, but larvae 

 from m.any other collections of other species from many other areas 

 also died from disease without resulting in the production of any 

 pale moths among the survivors. Similarly colored individuals of 

 M. californicum have been collected as adults, especially in the Great 

 Basin and southern Rocky Mountains, but in all cases the number 

 of such individuals is very small. Possibly they are the result of extreme 

 conditions which prevent the development of the normal color pattern, 

 or they could be caused by homozygous recessives or other rare gene 

 combinations. A similar situation occurs in populations of AI. incurvum 

 aztecum which are found around Mexico City. See the comments on 

 this subspecies for a discussion of this (page 185). 



Specimens Examined. — 579 (Museum specimens — 397 males, 14 females, 

 70 larvae; reared specimens — 45 inales, 53 females, plus numerous larvae and 

 egg masses). See Appendix I for collections made during this study (page 257). 



United States. — Arizona: Chiricahua Mountains; Christopher Creek, 

 Mogollon Rim (Gila Co.); Dewey; Garden Canyon, Huachuca Movmtains; 

 Hereford; Hot Springs; Huachuca Mountains; Madera Canyon, Santa Rita 

 Mountains; end of road, Madera Canyon, Santa Rita Mountains; Manzanita; 

 Oak Creek Canyon; Oracle; Palmerlee; Paradise; Payson; Pinal Mountains; 

 Pine Camp Ground, Pine (Gila Co.); Pine Crest, Graham Mountains; Pres- 

 cott; Ramsey Canyon, Pluachuca Mountains; Santa Catalina Mountains; 

 Santa Rita Mountains; Schnebler? Hill, Sedona; Sedona; SW Research Station, 

 A.M.N.H., 5 mi. W. Portal; Todd's Lodge, Oak Creek Canyon; Tonto Creek 

 State Fish Hatchery (Gila Co.); Turkey Flat, Chirichaua Mountains; White 



