360 
and fruit, from the common sessile Yucca filamentosa of our gardens to 
the arboreal forms, like brevifolia of the Mojave Desert and jilifera of 
Mexico. My remarks will be based chiefly on Yucca filamentosa, which 
is indigenous to the Southeastern States and is cultivated beyond its 
natural range, under a number of horticultural variety names, in our 
gardens. 
An examination of the flower will show at onee the peculiarities which 
Fic. 58.—PRONUBA YUCCASELLA: a, lar- 
va; b, 2 moth with closed wing; c, do. 
with wings expanded, natural size; d, 
side view of larval joint; e, head of 
larva, beneath; jf, do. above; g, tho- 
racic leg of same; h, maxilla; t, man- 
dible; 7, spinneret and labial palpi; 
k, antenna, enlarged. 
I have alluded to as characteristic of the 
genus. The stamens or filaments are bent 
away from the stigma and do not reach 
more than two-thirds the length of the 
pistil, the stigmal opening being at the 
tip of the prolonged style and nowhere 
within reach of the stamens, while the 
pollen either remains attached to the open 
and withered anthers or falls in different 
sized lumps on the underside of the peri- 
anth. It can not be introduced into the 
stigmatic tube without artificial aid, and 
the plant depends absolutely on the little 
white moth belonging to the Tineina and 
known as Pronuba yuccasella Riley (Fig. 
58). 
STRUCTURAL CHARACTERISTICS OF PRONUBA. 
Upon a superficial view, this little moth shows nothing very pecul- 
iar. The general coloration is white, the primaries being purely white 
on the upper surface, so that when at rest in the half-open flowers of 
Fic. 59.—PRONUBA YUCCASELLA: Generic characters—a, side view of head and neck of female de- 
nuded, showing how the collected load of pollen (1) is held by the tentacles (2); b, maxillary tentacle 
and palpus; c, an enlarged spine; d, palpus separated; e, scale from front wing; /, front leg; g, palpus; 
h, i, front and hind wings denuded; j, anal joint of female with ovipositor. 
