Z&Z BRITISH LEPIDOPTERA. 



grey, with a dull white, distinctly oblique, fascia, edged with dark 

 towards the base, and posteriorly rather concave ; it has also paler 

 cilia and shorter whitish antennae. There are specimens of N. malella 

 in which the anterior wings are of the same colour as in N. distin- 

 guenda, but that species is readily distinguished by the more brilliant 

 fascia being placed nearer the base, and by the distinct cilial line 

 (Heinemann). 



Egg-laying. — The egg is laid anywhere on the undersurface of a 

 leaf (Wood). 



Mine. — The mine, although small and narrow, begins coarsely ; it 

 is brown, generally much contorted, several mines being often crowded 

 together in a leaf. The gallery is filled with brown frass, very neatly 

 coiled, and is most constant and true to type (Wood). 



Larva. — The larva is yellow in colour; the head is dark-brown ; a 

 black, square-shaped surface spot is present on the underside of the 

 prothorax ; the ventral cord is black and very distinct, forming a chain 

 of black linear markings down the centre ; the urinary cords form a 

 pair of black lines on the dorsum of the hinder segments, and are also 

 plainly visible. The larva mines with the venter up, and shows the 

 dark ventral cord. 



Comparison of the mines and larvae of N. distinguenda and 

 N. betulicola. — The mines are small and narrow, especially that of 

 N. distinguenda, are generally much contorted, several often crowded 

 together in a leaf, and begin coarsely, very differently from the slender 

 and delicate commencement adopted by N. lapponica and N. confusella. 

 Here the resemblance between them ends. N. distinguenda fills its 

 gallery with brown frass, very neatly coiled, and is always most 

 constant and true to type. N. betulicola deposits its black frass 

 without any order, and is distinctly irregular in its practice; usually 

 it does not much more than half fill its gallery, but not unfrequently 

 it very nearly does so, the mine at the same time being narrowed and 

 shorter than usual, and coming extremely near the mine of N. luteella. 

 The irregularity, there can be little doubt, is dependent on the nature 

 of the leaves, for it will be found that the latter are appreciably 

 thinner, and their network of veinlets more open where the gallery is 

 only half filled, than where it is more completely so. Larvae : In N. 

 distinguenda the head is dark brown, a black, square-shaped spot 

 (skin mark) is present on the underside of segment 2 ; the ventral cord 

 is black and very distinct, and the urinary tubes are also plainly 

 visible. The larva of N. betulicola differs in the ventral cord and spot 

 on segment 2, being brown instead of black, and in wanting altogether 

 the urinary tubes (Wood). 



Cocoon. — The cocoons (2) average 2-2 mm. in length, and 1-75 mm. 

 in width. To the naked eye they are of a pale flesh colour, and most 

 resemble, of the great number of cocoons observed, those of N. luteella. 

 The flesh colour is quite maintained under the lens. In shape the 

 cocoon is inclined to the normal " mussel "-like structure, but is much 

 more triangular, the apex being quite pointed, one side being almost 

 straight, the opposite side and base being slightly convex. There is 

 no flattened lateral flange, the raised portion rising directly from the 

 edge. The surface is uniformly rough, and covered with loose flossy 

 silken ends. [Described June 15th, 1898, under a two-thirds lens, 

 from cocoons sent by Dr. Wood.] Wood says that " the cocoon is 

 spun above the ground, and is buff in colour." 



