72 NEW ZEALAND ENTOMOLOGY. 



alike, the only differences observable being in the length of 

 the perpendicular shaft and the direction of the horizontal 

 burrow, which is sometimes curved. These variations are 

 usually caused by the presence of other tunnels in the tree, 

 which the larva invariably avoids, although how it can 

 ascertain that it is approaching another tunnel before 

 actually reaching it, is hard to understand. As development 

 progresses in the pupa, it becomes darker in colour, espe- 

 cially on the wing-cases, which in some individuals show 

 the future black markings of the moth, as early as two 

 months before emergence. Others remain quite white and 

 soft, the green wings suddenly appearing through their 

 cases a fortnight or three weeks prior to the bursting forth 

 of the imago. Previous to this change the pupa works 

 its way up the vertical tunnel, lifts the trap-door, which 

 yields to the slightest pressure from within, and wriggles 

 along the horizontal burrow until it reaches the air, the 

 last three or four segments only remaining in the tree. 

 The thoracic shield then ruptures, and the moth crawls out 

 and expands its wings in the ordinary way, resting on the 

 trunk of the tree until they are of sufficient strength and 

 hardness for flight. 



The perfect insect, although it must be common, is very 

 rarely seen. It is best reared from the pupae, which can 

 be often successfully cut out of their burrows and kept 

 amongst damp moss until they emerge. It appears to 

 be much persecuted by birds, as we often observe its large 

 green wings lying about on the ground. 1 



The curious " vegetable caterpillar," which is usually 

 referred to this species, probably belongs to one of the 

 larger subterranean larvae of the family. 



1 For a more detailed account of the metamorphosis of this insect 

 see The Entomologist ', vol. xviii. p. 30. 



