32 



PROC. ENT. SOC. WASH., VOL. 20, NO. 2, FEB., 1918 



the ridges are slightly bowed. In Tischeriidae, Leucopterigidae 

 and Opostegidae they are straight, divergent, and extend back 

 and fuse with the ventral hind margins of epicranium. In the 

 NepticuUdae they are also widely divergent but do not reach the 

 hind margins. 



There are several other points of resemblance: the extremely 

 lateral position of setae La-2 on the labra of Tischeria (fig. 21) 

 and Ectoedemia (fig. 14); the strikingly similar maxillulae of 

 Proleucoptera (fig. 29) and Opostega (fig. 2) with their double 

 pair of elongate, anteriorly, projecting, and well spined lobes; 6 

 the gradual disappearance of setae from the same epicranial 

 areas and the similar arrangement of those that remain. 7 



Some of these developments might be attributed to purely 

 biological causes but their sum total and the facts that the same 

 tendencies manifest themselves in the production of heads so 

 radically different in superficial structure and designate meet 

 such various environment, indicate a close relationship and a 

 common ancestor for the group. The following tree shows their 

 probable derivation as it is suggested by the larval characters: 



Opostegidae 



Leucopterigidae 



(Aculei 



Micropterygidae 



lost) 



NepticuUdae 



Tischeriidae 



Aculeate ancestor 



The Leucopterigidae probably branched off from the Nepticulid 

 stem earlier than Tischeria from which it appears to have di- 

 verged, approaching in some ways more nearly to Opostega 

 Unfortunately for the perfect symmetry of our scheme it is the 

 only family of the group which has lost the aculai from the wings 

 of the adult. But of this we can only say as we do of so many 

 other structures, that it is lost. 



The writer is greatly indebted to Miss Mary Carmody of the 

 Bureau of Entomology for the excellent drawings that accom- 



6 For a comparison of the maxillulae of Ectoedemia see DeGryse (4, pp. 

 175-176). Nepticula has the same structures without the large chitinized 

 blades. Proleucoptera smilaciella Busck lacks the lower pair of project- 

 ing lobes so conspicuous in P. albella Chamb. 



7 Compare for example Tischeria with Proleucoptera (Figs. 24, 25, 33, 

 34) and Ectoedemia with Opostega (Figs. 8, 9, 10, 17). 



