Warr.—Leaf-mining Insects of New Zealand. 333 
later this will result in serious overcrowding and the last larvae to hatch 
will not reach maturity. On hatching, the larva burrows directly through 
the shell into the leaf-substance, the empty shell becoming filled with frass 
and firmly retaining its position. 
The Mine. (Plate 27, fig. 2; Plate 29, fig. 2.) 
The chief characteristics of the mine are: Firstly, the preliminary 6 or 7 
millimetres of the gallery are closely convoluted, vermiform, or spirally 
very little sign of it on the under-surface. In the second part of the mine 
Habits of the Larva. 
The first moult takes place where the first part of the gallery joins the 
second—that is to say, after the first moult the larva mines n a more set 
direction. The duration of the first stadium is subject to much variation 
owing to climatic conditions, and may be any time from a fortnight or 
even less in summer to several months in winter. The second moult 
margin of the gallery, within which will be found the cast larval head- 
piece. It is the obstruction by the cast headpiece that causes the larva 
