INTRODUCTION. 





The Ovum. 



The ovum or egg is more or less globular, usually with a sculp - 

 tured surface ; the colour changing considerably during the process 

 of development. There are two types of egg found in the Lepi- 

 doptera * : — (1) The upright egg with the micropyle at the top, 

 found in the Syntomidce, Arctiada', Noctuidce. Lymantriado', Hypsid<s^ 

 Notodontidce, Cossidce, Castniadcf, and probably the small families 

 derived from them, and in the Papiliones. (2) The flat egg with the 

 micropyle at one end, to which group all the other families belong. 

 The groups with upright eggs arose from the ancestral flat-egg 

 forms at several different points, and it will be noticed in the 

 phylogeny of the families that the only family with upright eggs 

 placed as giving rise to families with flat eggs is the Notodontido'. 

 It is, however, from ancestors of the present forms that the families 

 were derived, and probably the Notodontidce either still include 

 among their lower forms, or did so prior to the origin of the 

 Gymatophoridoi and Spliingidce, forms with flat eggs that would 

 still come within the definition of the family. 



The Larva. 



The larvJB of Lepidop>tera are essentially phytophagous, but in the 

 family Pyralidce an Australian Gallerid eats its way into and preys 

 upon the larvae of one of the large green species of Hepialus, and 

 several species of Phycids and Noctuids of the genus EidAemma live 

 on Coccids, a Lycaenid on Aphids, and some Tineidm on such sub- 

 stances as hair and horn. 



The larvEe are usually cylindrical and elongate, but shorter and 

 broader in the Lyaenidce, Zygcenidce, and Megalopygido', most 

 modified in the Limacodidce. They consist of: — (i; A head fur- 

 nished with strongly developed mandibles, simple eyes, antennae 

 which are usually rudimentary but developed in Eriocepliala, and 

 usually have a spinneret below the mouth, from which silk is 

 produced. (2) Thirteen somites, occasionally divided by transverse 

 furrows into two to eight annulets : of these, three are thoracic, 

 each bearing a pair of jointed corneous legs, and the 1st somite 

 a lateral spiracle, and the other ten abdominal, the 1st eight with a 

 spiracle, the last two without spiracles and almost completely fused, 

 usually scarcely separable in the higher families. Somites 6- 9 and 

 13 bear the paired sucker-like prologs, furnished, except in a few 

 cases, at extremity with minute hooks, which form a complete circle 

 in the generalized forms with incomplete pupae, and are present on 

 outer side only in the more specialized OhtecUe. In certain families, 

 as in nearly all Geometridce, many Noctuidce and Nolince, some of 

 the prologs are absent ; in the Ilegalopygidce they coexist with a 

 series of sucker-like pads on somites 5-10, whilst in the Litnacodidce 

 they are replaced by sucker-like structures on somites 4-11. In 

 the ancestral Eriocephalaf there are eight pairs of prologs, and 



* Dr. T. A. D. Chapman, Trans. Ent. See. 1896, pp. 567-587. 

 t Id., Trans. Ent. See. 1894, p. 335. 



