120 MISSOURI BOTANICAL GARDEN. 
its movements show that it seeks what little nectar it can 
find at the base of the flower, which it uses however, chiefly 
as a place of shelter. It may and I think does feed 
somewhat on the fallen pollen, and in so far interferes 
with pollination by the moth. The beetle is almost 
always found in pairs, the female quite gravid, and 
while her eggs have not yet been described, and the 
place of oviposition is yet unknown, they are in all 
probability laid in the ground, and the larva is known to 
be predaceous and to be one of the enemies of the common 
Apple Worm. None of the other insects have ever been 
observed to go to the stigma and none of them have been - 
observed to gather pollen. The few Hymenoptera, includ- 
ing the common Hive Bee, which are on rare occasions found 
about the flower, are accidental rather than habitual visi- 
tors, and get little satisfaction in the modicum of sweet 
they can find near the base of the flower. The slightly 
glutinous nature of the pollen, which is not easily dusted 
on to hairy insects, makes it extremely doubtful whether 
it is ever, even by accident, attached to the head of an in- 
sect that might by chance seek the stigmatic liquid, and 
the experiments I have made indicate that, with the long- 
styled Yuccas, a very thorough and effective insertion of 
the pollen grains is necessary for fertilization. These 
general conclusions have been confirmed by specific ex- 
periments made for the purpose; for over and over again 
I have excluded Pronuba by covering the whole panicle 
with gauze and have admitted all sorts of other insects in 
the hope of inducing fertilization; but in every case I have 
failed, whereas, whenever Pronuba has been admitted to 
the flowers, there has been evidence of her work and 
fructification. 
Pronuba yuccasella is found in all parts of the country 
east of the Rocky Mountains where the filamentose Yuccas 
normally range; but has not extended to all sections 
where they are cultivated. The time of its appearance, as 
we have seen, is strikingly coetaneous, east of the Missis- 
