54 



U.S. NATIONAL MUSEUM BULLETIN 2 55 



characters which may be taxonomically significant. For example, 

 it appears that the diameter of the signum is inversely proportional 

 to the length of the male genitalia (i.e., the longer the male genitalia, 

 the smaller the signum in the female). Furthermore, the distribution 

 of this character may follow that of genitalia length (see table 2) 

 and be directly associated with certain plant hosts. Busck (1947) 

 first noted these variations in the development of the female signum, 

 along with other genitalic characters, but concluded that no relation- 

 ships were involved and that only one species was represented. 



Certain characters of the male genitalia vary to a great extent, 

 but may be relatively constant within a given population. As a 



Table 2. — Genitalia measurements of male Tegeticula yuccasella 



