1892.] Botany. 775 
Pronuba is not attracted to the flower by nectar. As Trelease has 
shown,‘ large nectaries are present in Yucca, but frequently little 
nectar is produced. It is questionable whether that produced is ever 
utilized by Pronuba as she has never been observed to feed. This, as 
Riley observes, “ adds to the importance of Pronuba by showing that 
the acts of collecting pollen and transferring it to the stigma do not 
result in food compensation.” The eggs of Pronuba are deposited in 
the young Yucca capsule at this time and fertilization is necessary in 
order that the larve which feed on the maturing seeds may develop. 
Thus Pronuba insures the development of the seeds by pollinating the 
plant and is compensated by having her larve provided for, so far as 
food is concerned. if 
During the day the moth may be found in the flowers where they 
remain, their white color, being the same as the flower, protecting 
them. In early evening they begin their work. The males are 
stronger of wing and flit back and forth among the flowers. The 
female has a work to perform and she loses no time in frolic. Hers is 
the work of ovipositing and Yucca pollinating. It is surprising with 
what deftness, accuracy and understanding she proceeds about her 
task. She first begins by collecting a load of pollen, a stage difficult 
to observe but now authenticated by many observers. She may be 
seen quickly running to the top of the stamen, where she pauses, and 
bending her head down over the anther, with her tongue and maxil- 
lary palpi (wonderfully modified for this purpose) extended on the 
opposite side of the anther, she scrapes the pollen from the anther sacs, 
and with the aid of her front legs, shapes the gathered pollen into a 
little ball. She proceeds from anther to anther till a relatively large 
load is collected, often thrice as large as her head. With this, Riley 
observes, she flies to another flower usually before ovipositing. I have 
never observed the gathering of pollen but I have frequently seen the 
same moth pass from flower to flower and from plant to plant, ovipos- 
iting and pollinating in many ovaries without stopping to collect more 
pollen. In this way cross pollination, in most cases, must surely result. 
Equipped with her load of pollen, Pronuda proceeds to the further 
work of oviposition. She enters a flower and may be seen frequently 
for several minutes resting with the head toward the base of the flower, 
feeling around with the tentacles or slowly crawling around. Suddenly 
she awakens and with surprising activity rans rapidly around in the 
flower over the stamens and finally, in a few seconds, takes position 
“<The Nectary of Yucca,” Bull. Torr. Bot. Club, vol. xiii (August, 1886), p. 135. 
- 
