REVISION OF MOTHS OF PRODOXINAE 17 



in the history of the Prodoxinae in that plant genera other than Yucca 

 were exploited as hosts. Two plant genera are now represented, but 

 more may be discovered as other xerophytic plant groups such as 

 Nolina, Dasylirion, and Furcraea are investigated. Evidence is 

 beginning to appear to show the possibihty of a series of prodoxine 

 genera progressing from Prodoxus to Agavenema. Each major step 

 in the series may be represented by a distinct genus of moths that feeds, 

 perhaps, on a particular genus of plants. Morphologically, Mesepiola 

 is intermediate between Prodoxus and Agavenema; its life history is 

 unknown, but most likely the larva will be discovered as a borer in 

 Nolina or Agave. Agavenema, of course, may not represent the terminal 

 group in the evolutionary series; instead, some plant genus such as 

 Furcraea may harbor the most speciaUzed stem borer of this phjdetic 

 line. 



Two species of Agavenema are known presently, and future work 

 probably will reveal more. The tremendous success of the genus 

 Agave (approximately 275 species), as compared to that of Yucca (41 

 species), immediately suggests the possibihty of a somewhat com- 

 parable amount of speciation within Agavenema. Such a radiation, 

 however, may have never occurred ; instead, ^(/avenema may be repre- 

 sented by fewer species than Prodoxus. This could be true if (1) 

 Agavenema was of relatively recent origin (as is believed), or if (2) 

 the species are not host specific, but feed on a vide variety of Agave, 

 and, similarly, if (3) morphological and especially physiological 

 differences between the species of Agave are relatively sHght (at least 

 within the flower stalk), which, consequently would induce httle 

 speciation on the part of the moths. The final answer can be resolved 

 only after a considerable amount of field work has been performed. 

 As a possible parallel, several species of Megathymidae, particularly 

 the genus Agathymus, have undergone considerable speciation on 

 Agave, and it is likely that Agavenema, when better known, will show 

 this also. 



Biology 



Distribution. — The apparent center of dispersal for the Pro- 

 doxinae has been the Sonoran region of the southwestern United 

 States, particularly southern CaUfornia and Aiizona. CaUfornia 

 possesses the greatest concentration with a total of 4 genera, 12 

 species and 1 subspecies; Arizona is next with 9 species but has all 5 

 genera represented. Only one species, Prodoxus intricatus, does not 

 occur in the United States; thus giving a total of 16 species for this 

 country. 



Little is known about the distribution of the Prodoxinae in Mexico, 

 although it is probable that all 5 genera are present, at least in the 



