Tineidae 



& 



Fig. 262. P. yuccasella. a, lar- 

 va ; b, female moth with closed 

 wings ; c, do. with wings expanded ; 



d, side view of larval segment ; 



e, head of larva from below ; f, do. 

 from above ; g, thoracic leg of do. ; 

 h, maxilla ; i, mandible ; j, spin- 

 neret and labial palpi ; k, antenna, 

 enlarged. (After Riley, "Insect 

 Life," Vol. IV, p. 360.) 



pollen with her mouth, which is peculiarly modified to enable 

 her to do this, and then applies the pollen to the stigma with in- 

 finitely better care than it could be 

 done by the most skilful horticul- 

 turist usingthe mostdelicate human 

 appliances. 



There are several species of the 

 genus Pronuba, and they hold a 

 positive and well-ascertained re- 

 lationship to the various species 

 of the plants in the economy of 

 which they perform so important 

 a function. Pronuba yuccasella 

 pollenizes in the Eastern States 

 the blossoms of the common Yucca 

 filamentosa, and on the Western 

 plains it performs the act for the 

 blossoms of Yucca angustifolia. 

 Yucca brevifolia is pollenized by Pronuba syntbetica. Yucca 

 wbipplei is pollenized by Pronuba maculata. No doubt there are 

 other species of Yucca which will be ultimately discovered to have 

 species of Pronuba which are adapted in their organs to the 

 work of pollenation according to their peculiar requirements. 



The larva of Pronuba, after it has attained to full size, drops to 

 the ground, having three pairs of thoracic legs, which enable it 

 to move about and burrow into the earth. It 

 then undergoes transformation into the pupal 

 state. The chrysalis, which is depicted in Fig. 

 263, has the back armed with peculiar spinous 

 processes, which enable it to make its way 

 through the loose soil. 



The student who desires to become fully 

 acquainted with this interesting chapter in 

 insect life must consult the altogether admi- 

 rable papers written upon the subject by Pro- 

 fessor Riley, to whom we are indebted for 

 almost all that we know in regard to the 



Fig. 263. 



P. yuc- 

 casella. I, male chry- 

 salis ; m, female chry- 

 salis. (After Riley, 

 "Insect Life," Vol. 



subject. These papers may be found in the ' p ' 3 

 Publications of the St. Louis Academy of Science, the "Fifth 



442 



