REVISION OF MOTHS OF PRODOXINAE 



19 



Herbarium. The extreme northern and southern limits are rather 

 indefinite and in some cases may represent plant populations that 

 have escaped from cultivation, but which now are beheved to be 

 naturahzed. Through cultivation, the distribution of several species 

 of Yucca and Agave have become much more extensive than indicated, 

 especially in South America and thi'ough the Old World. The moths, 

 however, have not become established in such areas and evidently 

 cannot unless the host is represented by adequate populations that 

 are more or less contingent. Thus, in maps 1 and 2, 1 have attempted 

 to indicate only the native, or subsequently naturahzed, distributions 

 of Agave and Yucca. 



Plant hosts. — Besides Yucca and Agave, no other genera of plants 

 have been definitely estabHshed as hosts for moths of the Prodoxinae. 

 Future investigations may show that some of the larger species of 

 Nolina and Dasylirion are food plants, as well as certain other plant 

 genera mentioned in the following discussion. In general, these 

 plants are characterized in part as being xerophytic perennials which 

 typically produce a large, pithy flowering stalk and capsular fruits. 



Although the genus Yucca has received considerable attention from 

 several botanists over the past century, the classification of the group 

 is still in a state of flux, largely because of the extreme amount of 

 variation exhibited by most species. Webber (1953) considered this 

 variation to be of three types: (1) envu"onmental, (2) minor genetical, 



Map 2.— Distribution of tlie genus Agavg (exclusive of Manfreda). 



