216 Transactions. 



Distribution. 



I have come across this moth only in Dunedin, where its mines are 

 very numerous, and the food-plants are often badly infected. In the last 

 two years I have found larvae in each month except January and February, 

 when I have been out of Dunedin ; they may be found at almost any time 

 during the year. Ova were found to be most abundant in April, May, 

 September, and October. The imagines may be found at any time during 

 the summer months ; they are active in the sun about the food-plant. 



Food-plants. 



Olearia Traversii (akeake), JD. nitida (now 0. arborescens and 0. divari- 

 cata), 0. macrodonta, 0. Ciinninghamii (heketara), 0. Colensoi (tupare), 

 0. avicenniaefolia (akeake). Of these, 0. nitida and 0. macrodonta are 

 the ones most attacked. 



The Ovum and Egg-laying. 



The egg is relatively large, and when newly laid is bright blue in colour. 

 Empty shells are white and filled with frass. In shape oval, wafer-like, 

 domed above ; a narrow flattened and somewhat ragged fringe surrounds 

 the foot. The shell is strong, transparent, shiny, devoid of sculpture except 

 for a slight roughening. Dimensions are — total length, 0-48 mm. ; width, 

 0*38 mm. ; height, 0*12 mm. It is strongly attached to the surface of the 

 leaf, and persists for a considerable time even after the mine has been 

 vacated. The eggs are laid singly, but a considerable number may be 

 deposited on one leaf. They are laid on the upper surface, but otherwise 

 have no fixed locality, though the upper and outer two-thirds of the leaves 

 appear to contain the majority of the mines. Some ova may be found 

 laid on entirely dead portions of the leaf, over long-disused mines, and even 

 sometimes upon or overlaj>ping one another, when the larvae must perish. 

 The egg-capacity of the. moth is not known. The period of incubation may 

 be anything from seven days to a month, or longer, according to local 

 climatic conditions. 



The Mine. (Plate XLIII, figs. 1, 2.) 



This is a blotch on the under-surface of the leaf. The hatching of the 

 egg is made known by the leaf-tissue in its immediate vicinity becoming 

 dark purple. This dark-purple spot is the chief naked-eye characteristic 

 of this period distinguishing this species from N. ogygia, being absent in the 

 latter. The larva immediately eats its way through the bottom of the shell 

 into the leaf and descends to the lower cuticle. The first portion of the 

 mine is a narrow, fairly straight gallery (fig. 13), which can be traced on the 

 under-surface of the leaf by a slight prominence of the cuticle ; on the upper 

 surface a trained eye can follow its course, as this is marked out by a 

 number of very minute white dots, these being small areas of dry cuticle 

 where the larva has eaten nearer the surface. The average length of this 

 preliminary gallery is about 1 cm., and it now abruptly expands into a 

 relatively large blotch, which at first is more or less roughly circular in 

 shape, but in most cases soon becomes rectangular owing to the coarser 

 ribs of the leaf confining it within their boundaries. The area occupied 

 by the blotch is from 2 to slightly over 3 square centimetres. The larva 

 does not readily attack the coarser cell-walls of the internal leaf-substance, 

 but, separating the lower cuticle from these cells, it attacks the substance 

 within them, thus causing the characteristic external appearance of the 



