VOL. VIII, PP. 41-54, PL. IX JUNE 20, 1893 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON. 



FURTHER NOTES ON YUCCA INSECTS AND YUCCA 

 POLLINATION* 



BY C. V. RILEY, PH. D. 



PRONUBA MACULATA. 



Since the presentation, a year ago, of the communication on 

 "Some Interrelations of Plants and Insects," in which I sum- 

 marized what was then known of Yucca pollination and the 

 Yucca moths, some further interesting observations have been 

 made, and the facts which I have to present to-night should be 

 looked upon as additional to those set forth in the previous 

 paper (vol. vn, pp. 81-104). On account of the singular struct- 

 ure of Yucca whipplei, which was known to be pollinated by 

 Pronuba maculata, I was quite anxious to obtain the facts in. 

 reference to this species. The long stamens, the sticky and 

 abundant pollen, and the peltate stigma, with its long hyaline 

 papillae, are characters which would seem to facilitate ordinary 

 pollination, though the restricted style would render this more 

 difficult, and the peculiarities of Pronuba metadata, with its 

 modified tongue, and maxillary tentacles very long and attenu- 

 ated at tip, were, I felt quite sure, special adaptations to fit it 

 for its work. This Yucca is not only one of the most interesting 

 from the structure of its flower, but is one of the noblest of the 



* Presented at a meeting of the Biological Society of Washington, May 

 1893. 



6-Bioi,. Soc. WASH., VOL. VIII, 1893. (41) 



