252 Transactions. — Zoology. 



The passage from the larval burrow to the outer chamber 

 is effected by the pupa, which removes the operculum, and, 

 I believe, the external cover also, but this I have not been 

 able to verify by actual observation. An imago had failed 

 to emerge from one pupa which I took from an outer cham- 

 ber, the external cover being already removed. Here is an 

 interesting problem : the external cover is usually demolished 

 with considerable completeness, but the pupa, remaining as it 

 does with the anal segments within the larval burrow, could 

 not in many cases reach the external cover to remove it and 

 permit free egress of the imago. 



Examination of the pupa may here help us. The head, 

 prothorax, and mesothorax dorsally are hard, longitudinally 

 but finely corrugated on the head and mesothorax, irregu- 

 larly so on the post-thorax, which is smooth posteriorly. 

 Undoubtedly this is a protection to that portion of the con- 

 tained imago, and would resist tremendous pressure. One 

 would think the pupa requires less, not more, protection 

 than the larva, which has done all the boring, and in its 

 later days, having no more to do, it loses the dorsal hard 

 area (scutellum), becoming more fleshy. 



It seems that the removal of the operculum, and likewise 

 the external cover, is due to aerial pressure from within, 

 initiated by movement of the pupa — in fact, literally blown 

 off. It must be remembered that the pupa is located at the 

 lower end of the vertical burrow until the time of emergence. 

 The pupa in bulk approximates very closely to the circum- 

 ference of the burrow, and the segmental spines give it great 

 power in forcing its way upward. The anterior portion of the 

 pupa would necessarily need to resist great pressure, which, 

 as we have seen, is possible by the corresponding greater 

 strength of that portion. The pupa does not appear to ex- 

 pand when making its escape from the burrows. 



I have for several years taken annually a fair number of 

 imagines, both males and females, from the trunks of Hoheria 

 populnea, Cunn., where they may be found drying their wings 

 an hour or so before dark during the month of September in 

 this district. The females are very variable, males more con- 

 stant, the species being sexually dimorphic as regards wing 

 shape and markings. 



The males vary as regards the size of the typical white 

 spots of the fore wings, and in having occasional additional 

 ones, but always have faint pale-green ring-like markings also. 

 Unlike the majority of its sex, one male which I have taken 

 has all those usually pale-green markings of the fore wings 

 distinctly and decidedly white in colour. I propose for this 

 aberration the name " albo-extremus." It must be very rare, 

 as I never saw but the one specimen — which, indeed, I am now 



