LEPIDOPTERA HETEROCERA. 717 



any rate very much reduced, if not absent ; antennae extremely short. The 

 mouth parts are altogether rudimentary and no food is taken by the 

 imagos. The Swift-moths form a small but varied family, zoologically 

 very isolated. The members of it vary greatly in size, from small moths 

 to insects six or seven inches in breadth across the wings. The larvae 

 live on roots or the wood of trees and are usually bare, the pupae 

 are also subterranean and capable of moving through the earth. 

 In many anatomical details the Hepialidae show a great simplicity 

 of structure, e.g. the testes remain distinct, the nerve-chain and heart 

 show less concentration than in other moths, the tracheal system 

 resembles that of the larva, the nervuration of the fore- and hind- 

 wings is similar. Some species of the only British genus Hepialus 

 differ markedly in the appearance of the two sexes, but this difference is 

 not constant and varies greatly in different localities. The Australian 

 region seems to have most species, but the family is cosmopolitan. 



Fam. 30. Callidulidae. The wing nervures resemble those of the 

 Pyralidae. Frenulum absent or rudimentary. This is a small family of 

 day-flying, lisht moths resembling butterflies. It is confined to the south- 

 east half of Asia and the neighbouring islands. 



Fam. 31. Drepanulidae. Apex of fore-wing pointed or hooked in 

 many cases. Frenulum sometimes wanting. No maxillary palps, and 

 labial palps small. A small but cosmopolitan family. The larva has 

 but eight pro-legs and terminates in an up-turned process somewhat as 

 do the larvae of certain Notodontidae. The hooks on the pro-legs do not 

 form a complete circle. The cocoon is weak and formed amongst 

 leaves. Drepana and Cilix (which has one species that at rest resembles 

 a bird's dropping) represent the family in Britain. 



Fam. 32. Limacodidae. Allied in nervuration to the Zygaenidae, but 

 the sub-costal nervure anastomoses with the radial and is not united to 

 it by a cross-nervure. First maxillae reduced. Small, squat moths of 

 varying appearance which take no food in the imago state. Nocturnal. 

 The larvae have no pro -legs and are flattened and somewhat slug-like. 

 They eat leaves, but except when feeding the head is withdrawn 

 into the body. The elaborate cocoons are often attached to twigs or 

 leaves, and provided with a lid through which the imago emerges. They 

 are mainly a tropical family, but Heterogenea and Apoda (Limacodes) are 

 British. 



Fam. 33. Megalopygidae. Wing nervures resemble Zygaenidae but 

 in the fore-wing the three anal nervures are for the most part distinct. A 

 small family with very hairy larvae and imagos. The former are said 

 to have seven pairs of pro-legs. The cocoon is fitted with a lid. American. 

 Megalopyge and Lagoa. 



Fam. 34. Thyrididae. Allied to Pyralidae but with two anal nervures 

 in hind-wing and no maxillary palp. A small family of smallish moths, 

 mostly tropical. 



Fam. 35. Lasiocampidae. Antenna bipectinate in both sexes. No 

 first maxillae and no frenulum. The Eggar-moths are very hairy and often 

 of a brown colour, with considerable sexual dimorphism. The eggs are 

 smooth and sometimes concealed by hairs deposited by the parent. The 

 larvae are remarkably hairy. The pupa is enclosed in a compact, hard 

 cocoon. The family includes some hundred genera with five times as 

 many species. It occurs all over the world except in New Zealand. 

 Lasiocampa, Odonestis. Erio aster , Poecilocampa and Trichiura are British, 



