34 U.S. NATIONAL MUSEUM BULLETIN 2 55 



because the pollinator {T. synthetica) of Y. brevifolia normally oviposits 

 in the apex of the pistil; hence the absence of constricted fruit. 



It is not known to what advantage, if any, an arrestment of plant 

 growth in the immediate environs of the puncture would provide for 

 the egg or young larva. As discussed earlier, Riley observed the egg 

 to be inserted normally in the locular cavity and frequently on the 

 funicular stalk of the ovule. Largely for this reason, probably, he 

 supposed that rapidly developing ovules could crush any insect egg 

 in close proximity. Considering the shape and size of the egg of 

 T. yuccasella, however, this does not seem likely. 



Immediately following oviposition, the female climbs to the top 

 of the pistil (if she has not already done so) and commences, amid 

 considerable head and mouthpart movements, to work the pollen into 

 the stigmatic cavity. The behavior of the moth during pollination 

 is very characteristic and easily detectable, even from a slight distance. 

 The entire forward portion of the body of T. yuccasella undergoes a 

 series of rapid pumping or bobbing motions, during which time the 

 poUen is not merely deposited on the stigma but is actually forced into 

 the stigmatic tube. Portions of the mouthparts, notably the maxillary 

 tentacles, are held stiffly erect under the head during this activity 

 and appear to function collectively as a kind of plunger or ramrod. 

 For T. yuccasella, a series of approximately 10-35 "bobbing" motions 

 are conducted within an interval of usually less than 20 seconds in 

 order to accomplish pollination. 



It is possible that the behavioral pattern during pollination differs 

 somewhat between the species of Tegeticula. Trelease (1893) has 

 noted that the behavior of T. synthetica is similar to that of T. yucca- 

 sella. For T. maculata, however, he observed the female to be slower 

 and more deliberate in her movements while depositing the poUen. 

 Trelease partially attributed this difference in behavior for T. maculata 

 to certain unique features in the morphology of its host, Yucca 

 whipplei, particularly to the capitate stigma and to the fact that the 

 pollen is formed characteristically in a compact mass, or pollenia. 



Pollination does not always follow every act of oviposition. 

 Frequently as many as 3-6 eggs may be inserted into different areas 

 of a given pistil before the female visits the stigma. Following 

 pollination, she then may continue to lay eggs in the same pistil or 

 may leave to visit another flower. 



The activity period for the members of this genus may differ 

 greatly depending on the particular species. The activities of T. 

 yuccasella commence at about dusk and continue into the early hom's 

 of darkness. Copulation normally occurs at this time within the 

 blossoms and probably whenever males come into contact with 

 females. Trelease (1893) has observed the adults of T. maculata and 



