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



463 



oblique dorsal streaks (these vary somewhat) ; costal streaks usually alter- 

 nately slender and thick ; a fuscous apical spot : cilia grey, round apex 

 white, with two dark fuscous lines and a black apical hook. Hindwings 



fuscous-grey, cilia paler." 



Distribution. 



I liave so far found this species only on Mount Egmont, about 3,000- 

 4,000 ft., where it is quite plentiful. Pupae were obtained during December 

 and January, emerging in February. Young larvae were found in April 

 of 1917. Meyrick records it from "Wellington and Christchurch, in 

 September, January, and February ; four specimens. 



' Food-plant. 



Nothopanax arhoreum (whauwhaupaku). 



The Mine. 



The mine is a most characteristic one. It is rare to find more than one 

 mine in a leaf. The egg is invariably laid upon the upper surface near 

 the midrib, and generally in the basal portion of the leaf. The larva on 

 hatching at once mines into the leaf through the shell of the egg, and as a 

 general rule takes several spiral turns before mining in any definite direc- 

 tion. This spiral nature of the earliest portion of the mine is characteristic. 

 The mine throughout is a very gradually widening gallery, never becoming 

 blotched, and rarely do portions cross each other except in the smaller 

 leaves. The final width is about 2 mm. Its direction invariably takes it 



Figs. 28, 29. — Mines of P. aellomacha in leaves of Nothopanax arhoreum. 



(Two-thirds natural size.) 



along both sides of the midrib, this obstacle being crossed in its upper and 

 thinner part ; from these long straight portions a varying number of blind 

 arms or branches of varying lengths, mostly straight but sometimes slightly 

 curved, sprout out into the leaf. As a rule the greater number will be 

 confined to one half of the leaf. These blind branches sometimes follow 

 the course of the veins of the leaf, but most often do not, generally treating 

 these as no obstacle ; they do not often reach as far as the outer margin of 

 the leaf, but may do so, and may follow it a short distance ; the result is, 

 however, always the same — a single blind-ended branch, never loops as in the 

 case of P. panacifinens ; and rarely is any of the margin of the leaf so mined. 

 The branches are all more or less parallel to one another, and rarely 

 cross ; they are all more or less equal in width, about 2 mm. The mine 

 is found only in the younger leaves, and is pale green in colour, the tips of 

 the branches often being white, showing where the larva came close against 

 the upper cuticle. No evidence of the mine is to be found on the underside 

 of the leaf, and in its natural state the mine is not a very conspicuous 



