FURTHER STUDIES OF YUCCAS. 189 



pretty clear that this fluid is not derived from the septal 

 glands, its source is not evident. 



A number of small beetles and flies visit the flowers, 

 apparently attracted by the pollen, which in some cases 

 they have been seen to eat. As was noted last year for 

 glauca* these insects sometimes dislodge masses of 

 pollen from the anthers, and the length of the stamens in 

 baccata may frequently cause some of this to fall upon the 

 tips of the stigmatic lobes. In one case a small mass of 

 pollen was found in this position, and, in another, some 

 pollen had been pushed into the mouth of the stigmatic 

 chamber, evidently having fallen upon the petals and been 

 transferred to the stigma by the pressure of my hand as I 

 gathered the flower. In some such way, therefore, perhaps 

 exceptional pollination may be effected now and then in 

 baccata when Pronuba is not present ; but I should not ex- 

 pect this to be of frequent occurrence, and the observations 

 at Colton show that it must be rare or ineffective. 



The moths taken in the flowers of this species at Cabazon 

 and San Diego are somewhat larger than many specimens 

 of Pronuba yuccasella, and they appear to have the tip of 

 the abdomen, the maxillary palpi, and the antennae, as well 

 as the chitinized parts in general when denuded, a little 

 darker in color, but aside from these and the greater ease 

 with which their scales are rubbed off, I can detect no 

 characters by which they can satisfactorily be separated 

 from P. yuccasella of the Mississippi Valley and Rocky 

 Mountains, which is also said to be indistinguishable from 

 the moth of the Gulf region. f Like the eastern representa- 

 tives of yuccasella they rest within the flowers during the 

 day, with their heads directed toward the base of the 

 stamens, though they seem a little more ready to drop from 

 the flowers when disturbed. Unfortunately I have been 

 able to make no observations on their work, but the 

 females bear loads of pollen of the usual form, and fertil- 



* Cf. Riley, I. c. 125. 



t Professor Riley has since confirmed this conclusion. 



