24 U.S. NATIONAL MUSEUM BULLETIN 255 



series, consequently, may reflect, to some degree, the relationships 

 of the hosts. Prodoxus, which is restricted to the most primitive 

 genus of the Agavaceae (i.e.. Yucca), is believed to represent the most 

 primitive stem borer in the Prodoxinae. Likewise, Agavenema, 

 which is considerably more speciaUzed than Prodoxus, feeds on one 

 of the most advanced members of the Agavaceae, the genus Agave. 

 According to Hutchinson, the tribe Polyantheae contains the most 

 speciaUzed elements of the family; thus, the same may hold true 

 for any prodoxines which may inhabit these plants. Mesepiola is 

 suspected of being a borer in Nolina, a member of a group of plants 

 (Nolineae) which Hutchinson places between the tribes Yucceae and 

 Agaveae. Interestingly enough, these moths, on the basis of their 

 morphology, are intermediate between Prodoxus and Agavenema. 

 It shoidd be noted, however, at this point that chromosome data do 

 not support the general belief that Nolina represents a group that is 

 intermediate between Yucca and Agave. The karyotype of Nolina 

 is very different from the latter complex in possessing 38 somatic 

 chromosomes of varying sizes; an equal number also has been reported 

 for Dasylirion. 



The close affinities of Yucca and Agave are also demonstrated by 

 the Megathymidae. In a recent generic revision of this family, 

 Freeman (1958) lists the genera Aegiale, Turnerina, and Agathymus 

 as host specific on Agave. All species of the related genus Megathymus, 

 except one, feed on Yucca. Megathymus heulahae Stallings and 

 Turner is interesting in that it is restricted to an unusual Agave that 

 resembles a Yucca. The remaining genus of the family, Stallingsia, 

 is restricted to Manfreda, a group of plants formerly considered by 

 botanists to be a subgenus of Agave. 



In summary then, the relationships of the three known genera of 

 stem boring Prodoxinae suggest that one, relatively homogenous 

 group of plants has been exploited as hosts, and that Yucca was the 

 first to be so utilized. Future studies probably will show that addi- 

 tional moth and plant genera are involved in this association, and as a 

 result of such discoveries, the affinities of certain groups within the 

 Agavaceae may become better understood. Other plants, in addition 

 to those already mentioned, which should be investigated as possible 

 hosts for these moths are Beaucarnea (Mexico), Calihanus (Mexico), 

 Beschorneria (Mexico) , Furcraea (tropical America) , Manfreda (United 

 States, Mexico, Guatemala), and Polianthes (Central America, 

 Trmidad), Furcraea, a close relative of Agave, may prove particularly 

 interesting in that, like Agave, it produces a single, stout flower 

 stalk, which, in F. longaeva Zuccarini, may attain a height of 15 meters. 



Life history. — The remarkable association of the yucca moths 

 (i.e., Tegeticula and Prodoxus) with the yucca plant has been known 



