Watt. — Leaf -mining Insects of New Zealand. 201 



The imago of this moth is not very common in the field, though its 

 mines may be found in large numbeis on the food-plants. This may be 

 accounted for by the fact that it rarely flies except in bright sunshine, the 

 slightest dullness sending it to cover amongst dead vegetation, and in 

 crannies in the bark of the food-plant, from which it requires fairly rough 

 treatment to dislodge it, and even then will prefer to run to a new hiding- 

 place rather than take to the wing. At rest its coloration is very pro- 

 tective, and in consequence it is a most inconspicuous object. In the 

 sunshine its movements are quick and restless, and it rarely ventures far 

 from its food-plant. 



Distribution. 



Meyrick records the [original specimen from Dunedin in January : 

 I have found it there during the last iew seasons. Typical mines, but 

 empty, were found at Dawson's Falls, Mount Egmont, in December of 

 1917, in Olearia Cunninghamii (?). Not being in Dunedin during the 

 latter half of December and the first two months of the year, I have been 

 unable to record the activities of this moth during these months. My 

 first observations are dated July, 1919, when I obtained full-grown larvae, 

 these pupating during the early part of the month, and beginning to 

 emerge at the end of the first week of September. Larvae and cocoons 

 were again obtained in July, 1920. In September of both years imagines 

 were found, and many ova ; a few larvae were found early in the month 

 in 1919, these pupating in the second week and emerging during the 

 first week of November, while numbers of larvae were pupating towards 

 the middle of September, 1920, emerging towards the end of October. 

 A number of imagines were obtained about the middle of November. 

 There are therefore probably four, if not five, generations a year, but there 

 is a fair amount of overlapping. Imagos may be looked for towards the end 

 of June, early September, the end of October, and throughout November, 

 and in January and possibly March. It is probable that hibernation takes 

 place in the cocoon. 



Food-plants. 



Olearia nitida (now 0. arborescens and 0. divaricata) and 0. macrodonfa, 

 the former apparently being the favourite. Chiefly around the margin of 

 the bush. At Mount Egmont in 0. Cunninghamii (?). 



The Ovum and Egg-laying. 



The Ovum. — Oval, wafer-like, flattened against the leaf where it is 

 attached, rounded above. Micropylar end slightly broader than its nadir. 

 Around the outer margin of the egg the shell is slightly produced so as to 

 form a flattened foot or fringe closely applied to the surface of the leaf. 

 This fringe is a slight degree wider at the micropylar end of the egg. 

 A large number of eggs were measured, and their dimensions varied but 

 little ; in the fresh state this is the easiest way to distinguish the egg 

 from that of N. fulva, which is larger. Average length of fresh egg, 

 including fringe, 0-42 mm. : average transverse diameter, 0-30 mm. ; 

 average height, 0-12 mm. Empty shells are smaller than the above, and 

 without including the fringe, which is inconspicuous, the average length 

 and breadth is 0-40 mm. by 0-29 mm. There is a slight roughening of 

 the shell, but otherwise no definite sculpture or reticulation. The micro- 

 pyle is situated at the broader end of the egg, but its structure was not 

 observed. The shell is only very slightly roughened ; shiny, strong, trans- 

 parent. The colour is bright blue when first laid. As the embryo develops, 



