61 
the Yucca it is not easily detected. The under surfaces, however, are 
dusky, and offset in flight the whiteness of the rest of the body, so as 
to render the species somewhat difficult of detection while flitting from 
plant to plant. The male shows no very marked peculiarities to distin- 
guish him from the other members of the family, the most noticeable 
being, perhaps, the prominence of the exposed parts of the genitalia. 
The female, however, shows some remarkable structural peculiarities 
(Fig. 59), which admirably adapt her for the functions she has to per- 
form, for she must fertilize the plant, since her larve feed upon the 
seeds. 
Now, if I should ask any well-informed entomologist what are the 
characteristics of the Lepidopterous moth in the imago state, he would 
unhesitatingly answer: The lack of all prehensile organs, and a coiled 
tongue capable of sucking liquids. If, again, I should ask what distin- 
guishes the Lepidoptera from, say, the Hymenoptera, in the methods 
of oviposition, he would answer that the Lepidoptera lay eggs possess- 
ing, it is true, an infinite diversity of form, but usually attached exter- 
nally to some part of the food-plant of the species, while the Hymenop- 
tera, aS arule, secrete theirs, and are furnished with either a puncturing, 
boring, or sawing instrument for that purpose. The generalization 
would be entirely justified, though there are many curious exceptions 
to it, especially in the very group Tineina to which our Yucca Moth 
belongs. Itis, however, necessary to state these general truths in order 
to convey a just idea of the exceptional nature of the two organs to 
which I wish to draw your attention. The first is a pair of maxillary 
tentacles which are prehensile and spinous on their under surface. 
They are peculiar to the genus Pronuba and exist in no other genus of 
the many thousands of butterflies and moths.* The other organ is the 
ovipositor, which, instead of being a simple opening, as typically found 
in Lepidoptera, is here modified into a complex combination of lance 
and saw. Ordinarily it is withdrawn and hidden, but when in action 
is projected far beyond the tip of the abdomen, and is then seen to con- 
sist of two principal parts, the basal part being imbricato-granulate, 
7. €., having a delicate, file-like structure, the terminal part being smooth, 
but having near the end a dorsal serrate chitinous wing and a still more 
strongly toothed corneous tip. The internal structure is seen to consist 
of two stout rods extending along the thin walls to the very tip, and of 
a ventral canal or passage-way for the delicate oviduct, which is silk- 
like and elastic and may be extruded for a great length from an outlet 
near the end of the ovipositor. This oviduct is smooth basally, but 
armed along its terminal third with retrorse hairs, increasing somewhat 
in numbers and strength toward the tip, around which they are almost 
spinous. At first sight these would seem to be out of place and to im 
~ There are over 12,000 described species of Lepidoptera from Europe and America, 
and those from other parts of the world will double this number. Nearly as many 
more remain, perhaps, to be described. 
