168 BRITISH LEPIDOPTERA. 



The Nepticulid egg is rather large for the size of the moth, of the 

 " flat " type, ovate in character, roundish-oval in outline, some- 

 what domed above and flattened beneath, and, in spite of its gene- 

 ralised nature, not unlike that characterising certain superfamilies 

 belonging to the Sphingo-Micropterygid stirps. Chapman states that 

 it is not unlike that of Heterorfenea cruciata (asellus). The larva does 

 not, as is usual with lepidopterous larvae, eat its way out of the 

 micropylar end, or the upper side of the shell, but bores directly 

 through the base into the leaf below on which the egg is laid. As a 

 result of this the empty egg-shell is usually of a black or brown 

 colour, due to the presence of frass which the larva deposits in it as it 

 bores its way into the leaf. 



The position in which the egg is laid is usually very constant for 

 each species. Of 41 species, observed by Wood, 37 exhibited habitually 

 some preference as to the position selected. Sometimes this is merely 

 the selection of one side of a leaf in preference to the other, at other 

 times this preference extends to a particular part of the leaf such as 

 the extreme edge, the shelter of a projecting rib, or other position. 

 The egg of N. intimella is placed on the petiole of a leaf of 

 SalLc ruxselliana or on the upper surface of the midrib of .S'. caprca 

 for the larva burrows at first into the stalk or midrib, and only, in the 

 latter part of its life, mines the lamina of the leaf. The egg of N. ar<fi/ropeza 

 (apicelld) is placed on the petiole of an aspen leaf, the larva passing 

 its first stages within the stalk. X. regiella and N. if/nobilella blotch 

 hawthorn leaves, the mines of both beginning as galleries, which run 

 along the margin before proceeding towards the centre of the leaf. 

 The eggs of both species are laid on the underside of the lobes, that 

 of N. rei/iella immediately under the edge, whilst that of X. if/nobilella 

 is placed well away from it, often quite in the middle of the leaf. 

 Wood says that there is good reason for this extra precision on the 

 part of N. reffiella, for its gallery being short and coarse, if it did not 

 start true from the first, all its gyrations might fail to carry it to its 

 proper situation, whilst the gallery of .TV. if/nobilella, being long and 

 slender, is sure, sooner or later, to reach the edge, and give the larva 

 the necessary knowledge of its whereabouts. In some cases there 

 appears to be no very special reason for this fixed habit, yet variation 

 in this respect scarcely ever occurs, and the position of the egg appears 

 to be quite as reliable a character for the recognition of the species as 

 many others on which the naturalist has to depend, e.g., the first part 

 of the mine of N. aeneofasciella is a very long and slender gallery, just 

 like the mine of N.frayariella (or N. gei) ; the larvae, too, are very similar. 

 At this early stage, therefore, a mine of the latter species in a leaf of 

 agrimony (and such an occurrence often happens) could not well be 

 distinguished from that of the former, if it were not for the fact that 

 the egg of X. aeneofascidla is always laid on the underside, and that 

 of N. <jei on the upperside, of a leaf. A T . pygmaeella and N. gratioxella 

 both frequently lay on the narrow leafy frill that edges the 'stalk of a 

 hawthorn leaf ; both mines keep along the edge of the leaf, and are so 

 very much alike that nothing but the position of the egg can determine 

 the species forming the mine, the egg of N. pygmaeella being laid on 

 the upper, and that of X. gratiosella on the lower, surface of the frill. 



One of the four exceptions referred to by Wood as varying in the 

 position in which the egg is laid is iV. salicis, which, he says, lays its egg 



