32 U.S. NATIONAL MUSEUM BULLETIN 2 55 



May, 1888. As soon as the pods were received, the larvae emerged 

 and entered the ground; some of them forming cocoons at this time. 

 A few larvae, however, did not construct cocoons until the end of 

 1889, or more than a year after they were received. One larva was 

 discovered still living and unchanged inside its cocoon, in August, 

 1891, or nearly two and one half years from the time it left the fruit. 

 Most of the adults that were reared successfully from KUey's series, 

 however, emerged the following spring in March or April. An even 

 greater extension of the larval stage has been noted for Prodoxus 

 quinquepunctellus (see p. 69). 



Pupa. — As outlined above, pupation for all species of Tegeticula 

 occurs inside an earthen cocoon, underground, and is preceded by a 

 prolonged period of larval hibernation. The actual length of the 

 pupal period is relatively short and probably does not exceed a week 

 or two in most instances. 



Structiu-ally, the pupae of Tegeticula are characterized by the pres- 

 ence of stout spines arising from the abdominal tergites (fig. 26). A 

 comparison of this heavUy-armed form with the smoothly-textured 

 pupa of Prodoxus immediately suggests a basic biological difference 

 between these two genera, and, indeed, there is. The presence of 

 these spines in Tegeticula probably are of benefit to the pupa in working 

 its way out of its buried, ceU-like cocoon, and upwards through the 

 soil untU it is at least part way out of the ground. 



Adult. — Emergence of the adults usually occurs in the spring, 

 in association with the flowering period of most species of yuccas. 

 It has been observed that the males of T. yuccasella emerge slightly 

 earlier than the females. As soon as flight is possible, the moths fly 

 to the nearest yucca flowers, which usually are very near the immediate 

 area of pupation. From then on, the behavior of the female follows 

 a pattern that has proven to be one of the most interesting associa- 

 tions in the animal kingdom. 



The exact sequence of events following emergence may vary some- 

 what; it is probable that, in most instances, the newly emerged fe- 

 male, on reaching the fu-st blossom, begins to gather pollen. Im- 

 mediately prior to this activity, the moth typically runs about the 

 bases of the stamens and then quickly climbs up the inner side of a 

 filament (Trelease, 1893). With coordinated movements of the head 

 and mouthparts (the maxillary tentacles in particular), she succeeds 

 in scraping pollen from the anther; then with the aid of her forelegs, 

 the pollen is molded into a ball and firmly worked into a natural 

 pocket under the head. Several stamens and more than one flower 

 may be visited before the pollen gathering impulse subsides. Eventu- 

 ally the female climbs a pistil and assumes a position favorable for 

 egg laying (fig. 35). 



