232 The Orders of Insects 



in the form and neuration of their wings — except that the sub- 

 costal nervure is simple and that there are fewer cross-nervules — as 

 well as in the possession of functional mandibles by the pupa. But 

 in the imago the mandibles have vanished and the gales of the first 

 maxills form a suclcing-tube as in Lepidoptera generally, though 

 the organ is short in this family. The Eriocraniids are small 

 moths closely like those of the preceding family in appearance. 

 The footless larvje mine the leaves of trees and the pupal stage is 

 passed underground. As in the preceding family the pupa is 

 "free." The family, containing but a single genus and a dozen 

 species, is confined to Northern and Central Europe. 



Hepialidae. — The Hepialida; or Swift Moths resemble the two 

 preceding families in wing structure, a jugum being present and 

 the neuration in fore and hind wings being closely similar. But 

 they agree with the following families in the absence of mandibles 

 in the pupa as well as in the imago. The palps of the first maxillx, 

 well-developed in the two preceding families, are wanting in the 

 Hepialidse ; these jaws as a whole indeed are vestigial, no food 

 being taken in the perfect state. The Swift Moths are large or 

 moderate-sized insects usually brown or yellow in colour of the 

 wings which are sometimes adorned with metallic spots. Their 

 larvje — of the usual lepidopterous type with ten pro-legs — live 

 underground and feed on roots; the "incomplete" pupjE also are 

 subterranean. The family does not comprise many genera, but is 

 world-wide in its range ; the only British genus is Hepialus. 



Zygaenidae. — The Zygcenida or Burnet Moths are small day- 

 flying insects adorned with bright metallic colours — in tlie two 

 British genera {Zygcena and Ino) scarlet and black, or green. The 

 forewings, with three anal nervules whereof two are confluent, are 

 narrow, and longer than the hindwings, in which three distinct 

 anal nervures are present, ai.d the sub-costal nervure is joined to 

 the radial by a short cross-nervule ; vestiges of the median trunk 

 nervure can often be traced in all the wings traversing the discoidal 

 cell. There is, as in all the succeeding families, no jugum, but a 

 frenulum is present. The feelers are rather long, stout, and taper- 

 ing with short processes or pectinations. The sucking-tube is 

 developed, but the first maxillary palps are vestigial. In the 

 structure of the imago the Burnets are less primitive than some 

 other families, but the pupa has as many as five movable segments 

 in the abdomen. It is protected by an elongate cocoon spun on 

 the food-plant. The larvae, with the usual five pairs of prolegs, 

 are stout and cylindrical, feeding openly on various plants, and 

 often conspicuously marked with black and yellow. The family is 

 very widely distributed, and rich in genera and species. 



Chalcosiidae. — The ChakosUdce are a family of tropical day- 

 flying moths of brilliant coloration, allied to the Zygznids with 

 which they agree closely in structure. The wings, however, are 

 less narrow in form and the feelers have longer pectinations which 



