290 



THE STUDY OF INSECTS. 



three-branched with them, whereas it appears four-branched 

 in the Drepanidae (Fig. 346). 



Although the humeral angle of the hind wings is greatly 

 developed in these moths, some of them retain the frenulum. 



FIG. 346. Wings of Oreta rosea. FIG. 347. Wings of Platypteryx arcuata 



When the frenulum is present it is borne at the end of a 

 long thickened portion of the wing, so that it is at a con- 

 siderable distance from the point where the wing is attached 

 to the body (Fig. 347).* 



The larvae are remarkable in having the anal prolegs 

 rudimentary, and the caudal segment prolonged into a more 



* We class the Drepanidae among the Frenulum-conservers, although 

 many of them have lost the frenulum. Among the true Frenulum-losers the 

 loss of the frenulum occurs while the race is still in a very generalized con- 

 dition, no trace of a frenulum being found among these insects except a rudi- 

 ment in the most generalized forms (Bombyx, Cicinnus). In the Drepanidae, 

 however, the frenulum is retained by very highly specialized forms. There is 

 a striking similarity in this respect between this family and the more 

 specialized Geometrids. 



