3¢2 
only specifically but generically, they are derived from one and the same ancestral 
form? Pronuba, depending for its existence upon the pollination of the flower, is 
profoundly modified in the female sex in adaptation to the peculiar function of pol- 
lination. Prodoxus, dwelling in the flesh of the fruit or in the flower stem, and only 
indirectly depending upon the fructification of the plant, is not so modified, but has 
the ordinary characters of the family in both sexes. In the former the larva quits 
the capsules and burrows in the ground; it has legs to aid in its work, while the 
chrysalis is likewise beautifully modified to adapt it to prying through the ground 
Ci 
Fic. 71.—PRODOXUS DECIPIENS: a, larva; b, head from above; c,d, left jaw and antenna; e, pupa; 
J, infested stem cut open to show the burrows, castings, cocoons, and pupa shell (A); all enlarged but 
Ff, the hair line between a and e showing natural length. 
and mounting to the surface. The latter, on the contrary, never quitting the stem, 
has no legs in the larva state, and in the chrysalis state is more particularly adapted, 
by the prominence of the capital projection, to piercing the slight covering of thestem 
left ungnawed by the larva. The former is very regular inits appearance as a moth 
at the time of the flowering of the Yuccas in their native range. The latter appears 
earlier, as the food of its larva is earlier ready, and the female could not oviposit in 
the riper stem. 
OTHER SPECIES OF PRODOXUS. 
Some ten species of this genus Prodoxus have been described, all of 
them having the very same structural characteristics and in the adoles- 
cent states being scarcely distinguishable. Prodoxus decipiens is asso- 
ciated with Pronuba yuccasella east of the Rocky Mountains, and 
Prodoxus sordidus is similarly associated with Pronuba synthetica, breed- 
ing in the flower-stems of Yucca brevifolia. All the other species are 
associated with Pronuba maculata, breeding either in the base of the 
capsules or in the flower-stem or the main stem of Yucca whipplert. I 
