174 



THE POPULAR SCIENCE MONTHLY. 



what and where to seek, often find this moth, either singly or in 



pairs, resting with folded wings within the half-closed flowers. 



It is then not only hidden from ordinary view, but well protected 



by the imitative color of the front wings with that of the flower, 



so that close scrutiny is necessary for its detection. If we visit 



the plant after 



"... the garish day 



Has sped on his wheels of light away," 



and when, with full-blown perianth, the yucca stands in all her 

 queenly beauty, and sends forth her perfume more strongly upon 

 the night air, we shall, with a little patience, meet with this same 

 moth, flitting swiftly from flower to flower and from plant to 



plant the dusky nature 

 of the hind wings and of 

 the under surface of the 

 front wings almost com- 

 pletely offsetting and neu- 

 tralizing, when in motion, 

 the upper silvery white- 

 ness of the latter, and 

 thus still rendering the 

 insect a little difficult of 

 detection. It is principal- 

 ly the male which we thus 

 see flying and, by the aid 

 of a " bull's-eye," we shall 

 find the female for the 

 most part busily at work 

 in the flowers. He, with 

 relatively stronger wing- 

 power, can afford to spend 

 in the most pleasurable way the few brief days allotted to him ; 

 but she is charged with a double duty, and loses little time in its 

 performance. As a part of the maternal task of continuing her 

 race, she must act as foster-mother to the plant in order to insure 

 a proper supply of food to her larva?, which, as we shall presently 

 see, feed on its seeds. 



As preliminary to a better understanding of the habits of the 

 female, it will be well to draw attention to those structural pecul- 

 iarities which distinguish her from all other species of her order, 

 and which so admirably fit her for the work she has to do. Fig. 

 3 gives some details of the head (a), and an important structure 

 which more particularly characterizes her and interests us is the 

 maxillary tentacle, shown with its palpus at b. She has a pair of 

 these organs, which are prehensile and spinous, and it is chiefly 

 by means of these that she is able to collect and hold a relatively 



Fig. 3. Generic Characters of Pronuba yuccasella : 

 a, side-view of head and neck of female denuded, 

 showing how the collected load of pollen (1) is held 

 by the tentacles (2) ; b, maxillary tentacle and pal- 

 pus; c, an enlarged spine; d, palpus separated; e, 

 scale from front wing ; /, front leg ; ff, labial palpus ; 

 A, i, front and hind wings denuded ; j, anal joint of 

 female with ovipositor all enlarged. 



