REVISION OF MOTHS OF PRODOXINAE 15 



presence of maxillary tentacles in Tegeticula and their apparent re- 

 duction in Prodoxus probably is of phylogenetic significance; however, 

 as noted on page 7 and in figure 51, any indication of this structiu-e's 

 former presence in Prodoxus is slight. Thi'oughout the Prodoxinae an 

 increase in the overall size of the compound eyes is apparent, Tegeti- 

 cula possesses the smallest eyes in the subfamily, whereas Agavenema, 

 one of the most advanced genera of Prodoxinae, has the largest pair! 

 Another evolutionary tendency that progresses throughout the sub- 

 family is the reduction of the signum in the female. The rather 

 spectacular, many rayed signa of Tegeticula (fig. 136), which super- 

 ficially resemble the single signum present m Atteva (Yponomeutidae), 

 gradually have become reduced through some genera of Prodoxinae 

 and completely lost in the genus Agavenema. 



One fact which seemingly contradicts Tegeticula^ s apparent antiquity 

 is the absence of insect parasites attacking that genus. Insect para- 

 sitism has developed within Prodoxus, but perhaps not in Tegeticula 

 (see p. 42). This phenomenon suggests that Prodoxus may be older 

 than Tegeticula, which is not believed to be the case. If no parasites 

 have evolved on Tegeticula, then it would seem very likely that the 

 distinctly different life history of this genus, as compared to that of 

 Prodoxus, is in some way reponsible for the observed absence of insect 

 parasites. 



Two general tendencies (see diagram 1, B and B') seem to have 

 developed early in the history of the Prodoxinae. One division (B) 

 is characterized by those species which have retained a seed boring 

 larva, or which have become secondarily adapted to a stem boring 

 habit (C). In addition, the members of this division and its prede- 

 cessors (A) gradually became more intimately associated with the 

 reproductive parts of their hosts, to the extent that pollination was 

 accomplished during the coiu'se of oviposition. The possible com- 

 bination of pollen feeding by the adult in connection with the deposi- 

 tion of eggs in some part of the flower, particularly the pistil, may have 

 initiated occasional or accidental visits to the flower stigma which 

 resulted in the fertilization of the ovules. Early in the history of 

 Yucca, other insects probably were responsible for pollination, but 

 with the fusion of the stylar lobes of the pistil and reduction of the 

 nectaries (Trelease, 1893), accidental pollination by these insects or 

 other agencies became less reliable and eventually impossible. Before 

 this stage was reached, however, ancestral Tegeticula was completely 

 dependent upon the development of the yucca fruit (i.e., a true seed 

 borer), and had developed the specialized maxiUary appendages 

 necessary for poUinating its host. The gradual modifications of the 

 moth's life history (and mouthparts) probably coincided with the 

 gradual changes which occiu'red in the yucca flower. 



