Watt. — Leaf-mining Insects of New Zealand. 



445 



• Food-plants. 



Coprosma grandifolia (kanono, raurakau), C. tenuifolia (karamu), C. liicida 

 (karamu), C rohnsta (karamu), C. retusa (taupata). 



It was chiefly in the young plants of these shrubs that the mines were 

 found, and within a foot or so of the ground. No doubt other species of 

 Coprosma are also attacked. 



Egg-layimj. 



The ovum has not yet been observed. It is laid, however, invariably 

 on the under-surface of the leaf, and as a rule near the midrib, and in the 

 lower (basal) half of the leaf. Laid singly, and rarely more than two on 

 any one leaf. ' . 



The Mine. 



The larva mines directly into the leaf through the bottom of the egg. 

 The mine is at first a long, slender, slightly tortuous, gradually widening 

 gallery ; the first centimetre or so being on the under-surface of the 

 leaf, close against the cuticle, showing up white and silvery by reflected 



Fig. 2.-^Mine of P. zorionella in Coprosma. (Two-thirds natural size.) 

 (X — X, point where the mine leaves the under-surface of 

 the leaf and comes close under the ujiper cuticle.) 



light. The remainder of the mine, however, is on the upper surface. In 

 the last stage the gallery expands, more or less abruptly, into a large 

 irregular blotch. The gallery at first is about 0-5 mm. in width, its 



Fig. 3. — Trace of mine of P. zorionella in Coprosma. (Two-thirds 

 natural size.) (X — X, point where mine changed from 

 lower to upper portion of the leaf.) 



margins regular ; on the upper surface of the leaf, however, the margins 

 become irregular and slightly serrated, the margin of the blotch being very 

 irregular as a rule, but the dentations are comparatively large and rounded. 

 The gallery may attain a length of from 4 in. to 6 in., according to the 



