146 MISSOURI BOTANICAL GARDEN. 
curved but pointing posteriorly, near the anterior border of joints 6-11; 
joint 5, which is so strongly armed in Pronuba, being here perfectly 
smooth. Joint 12 in both sexes is unarmed as in J‘ but not in the - 
Pronuba, while the terminal subjoint is much swollenand curved upward, 
with two minute spines taking the place of the broader, compressed 
processes in Pronuba. The capitate point is much stouter and beak- 
like, flattened and somewhat excavated laterally, so that the upper edges 
form each a sharp carina. The sexes are only distinguishable by the 
somewhat less swoolen sub-joint in the 9 and her longer leg-sheaths, 
which reach a little beyond the tip of the body, whereas in the o' they 
fall short of the tip. 
IMaGo &, (Fig. 2). Average expanse 16 mm. In general appearancc 
closely resembling Pronuba yuccasella, but the upper surface is ordi- 
narily more silvery and less creamy in appearance, and the dark 
shades, as of the eyes and the dark hairs of the palpi, front legs and tarsi 
and at the base of the costa on primaries, are more pronounced and black- 
ish. The under surface is somewhat darker, and the tip of the abdomen 
not truncate but pointed, and slightly beveled off superiorly. The 
terminal joint is swollen and darker than in Pronuba. The ovipositor 
is stout, dark brown, laterally flattened, between three and four times as 
broad as in Pronuba, shorter, the sculpture of basal portion closer, finer 
and ribbed, the tip obliquely cut off below and having a series of minute 
teeth, the ventral one being more conspicuously produced, and a series 
of eight or nine more prominent teeth along dorsal edge, while two dis- 
tinct grooves run along the whole length and several smaller ones are 
noticeable near the tip. (Fig. 3, a, d.) 
3d’, Somewhat smaller than 9, the genitalia being more elongate and 
prominent than in Pronuba, the claspers extending fully twice as far, 
less recurved, and having on the lower border 4 small black points or 
tubercles, equidistant from each other. (Fig. 3, f, g-) 
Described from numerous specimens of both sexes, 
either found in the flowers or reared from the stems of 
different species of Yucca throughout the eastern States. 
All the specimens obtained or reared east of the Missis- 
sippi have been immaculate, with the faintest tendency to a 
few minute spots; but western forms, especially those from 
Texas and Colorado, show a greater tendency to maculation, 
the number of spots ranging from 1 to 5 or more, usually 
arranged along the middle in the form of a broad W, a dot 
representing each angle and each outer tip. When the 
basal spot alone is absent the four remaining present the 
figure of a rhomboid. When it is absent and there is 
another spot posteriorly we have the W inverted. When a 
single spot is present there is no regularity in its position, 
and it may be differently placed on the two opposite wings 
of the same specimen. There may also be more spots on 
one wing than on the opposite one, while I have seen speci- 
mens with the thorax spotted with two metathoracic mesial 
