338 TRANS. ST. LOUIS ACAD. SCIENCE. 



Theresa^ Doubl.) Again, in most Hesperians the club tapers, or 

 is curved at tip ; but there are all degrees of variation, from the 

 extremely curved club of Epargyreus Tityrus (Fabr.) to the 

 straight and blunt club of Oarisma Poweshiek (Parker). The 

 small head and subobsolete spurs in Tuccce are abnormal com- 

 pared w^ith either family ; for most of the Castnians have the spurs 

 much as in Flesperia, and the head almost as broad as the tho- 

 rax. In the stiffer, relatively shorter antennas, with large club ; 

 in the spines w^hich stud the tibiae,* as vv^ell as in the stoutness of 

 the thorax and abdomen, Tuccce is again Hesperian rather than 

 Castnian. The Castnians, like the Uranians and many other 

 exceptional moths, resemble the butterflies in being day-flyers ; 

 but the position of the wings in repose, which is a more impor- 

 tant character, is said by all observers to be similar to that of 

 Catocala^ Drasteria^ and other Heterocera, viz., deflexed or 

 incumbent. 7ucccb^ both in manner of repose, in color, and in 

 pattern, is a staunch Hesperian. 



In short, a careful consideration of the characters of our Yucca 

 Borer shows that in all the more important characters it is essen- 

 tially Hesperian ; and that in most of those characters by which 

 it differs from the more typical species of that family — as in the 

 small spurs, in having only the apical ones on the hind tibise, in 

 the tibial spines, and difference in size of legs — it is more Rho- 

 palocerous than Heterocerous. The same holds true when we 

 consider the adolescent states. In the small head of both larva 

 and imago, and in the very large abdomen, it is abnormal ; but 

 these characters are traceable to the abnormal larval habit, and 

 are very unimportant compared to the pterogostic and other char- 

 acters cited. I have long since concluded that general larval form 

 and appearance is so dependent on habit and so variable accord- 

 ing to habit, that it is less valuable than more minute structural 

 characters, and that for purposes of classification it has even 

 less value than egg- structure, and infinitely less than imaginal 

 characters. All endophytous Lepidopterous larvae, of whatever 

 family, have certain general resemblances that are a consequence 



f In the Castnians that I have been able to examine none of the tibiae have spines, while 

 those on the tarsi are very minute : the middle tibiae have a pair of unequal, prominent sub- 

 apical spurs, and the hind tibiae have two similarly unequal pairs, Ihe anterior pair from 

 about the terminal fiflh. 



