798 MICROPTERYGINA 



ever given rise to other branches forming distinct families, all 

 trace of their existence seems to have been lost. 



Imago with forewings and hindwings more or less semioval, 

 termen and dorsum forming a nearly uniform curve. 



Type of markings : forewings with an irregular marbling or 

 reticulation, tending to form transverse fasciae ; hindwings 

 without marking. 



Larva with few hairs, with 10-16 prolegs, or apodal, living 

 concealed. 



Pupa in Hepialidae with segments 7-11 and in 12, in 

 Micropterygidae with all segments free. 



TABULATION OF FAMILIES. 



Maxillary palpi well-developed ; tibial spurs present 



2. MICROPTERYGIDAE. 

 obsolete; no tibial spurs 1. HEPIALIDAE. 



1. HEPIALIDAE. 



Head rough. Ocelli absent. Tongue obsolete. Maxillary 

 palpi obsolete. Tibiae without spurs. Forewings : all main 

 veins and costa connected by bars near base, Ib furcate, forked 

 parting-vein strong. 



By no means an extensive family, yet of universal distribu- 

 tion. It stands more conspicuously isolated than any other 

 group of Lepidoptera, for although it is without doubt a 

 terminal development from the Micropterygidae (that is, one 

 from which no existing family has originated), the gap between 

 them is considerable ; exotic genera, whilst differing in various 

 details, are remarkably uniform in the more important 

 peculiarities of structure, and do not at all tend to bridge the 

 gap. The relatively large size of the Hepialidae (of which some 

 exotic species exceed six inches in expanse of wing) may be 

 attributed to the larval habits, which render these insects 

 independent of the seasons or fluctuations of food-supply, thus 

 removing the check which ordinarily limits growth. The 

 modified type of neu ration may have resulted directly from the 

 increase of size, involving a great strengthening of the main 

 veins beneath the costa to support the weight. As a con- 

 sequence of this strengthening, the flight of the larger species 

 is very powerful ; and to this, combined with a choice of larval 

 food which is often rather indiscriminate, may perhaps be 

 ascribed the wide range of the group, rather than to its antiquity. 



