274 Transactions. 



Imago. 



The imago has already been completely described by Meyrick (Trans. 

 N.Z. Inst., xvi, p. 62) and by Hudson (N.Z. Moths and' Butterflies, p. 53. 

 pi. 6, figs. 30 and 31). 



Distribution. 



Waitakarei Ranges (Auckland) ; Wanganui. very common from August 

 to May; Wellington; Christchurch and Duhedin, from October to Mav ; 

 Ashburton ; West Plains : Invercargill. taken at light in April. 



Art. XXIX. — Contributions to the Study of New Zealand Entomology, from 

 an Economical and Biological Standpoint : No. 4 — Phorocera nefaria 

 Hutton ; No. 5 — Psychoda conspicillata Hudson ; No. 6 — Syrphus 

 ropalus Walk. ; No. 7 — Phytomyza albiceps Mg. (Diptera). 



By David Miller and Morris N. Watt, F.E.S. 



[Read before the Wanganui Philosophical Society, 23rd November, 1914.] 



Plates II. III. 



No. 4. Phorocera nefaria Hutton. 



For the original description of this fly see Trans. N.Z. Inst., vol. 33, 

 p. 59, and vol. 36, p. 151. 



Since nothing has yet been published concerning the habits and life- 

 historv of this Dipteron. which belongs to the parasitic family Tachinidae, 

 the following note may be not uninteresting. The larva is an internal 

 parasite of the larva and pupa of the common cabbage-tree moth, Venusia 

 verriculata (see Trans. N.Z. Inst., vol. 47, p. 271). The larvae of this 

 moth feed in the crevices between the innermost leaves of the cabbage-tree 

 (Cordyline australis), and so it is difficult to see how they become attacked. 

 It is quite possible that the fly deposits its ova on the leaves, and the 

 young maggots on hatching seek out and penetrate their host. But this is 

 only speculation. Only actual observation will reveal the secret, and so it 

 is likely that some little time will elapse before we can complete this very 

 interesting life- history.* The larva, when full-grown, emerges from the 

 pupa of its host, and pupates, being protected by the light cocoon spun 

 by the moth-caterpillar just prior to its final moult and for its own protection. 



The pupa is dark red in colour ; cylindrical, and smooth ; the anterior 

 end slightly smaller than its nadir, which is somewhat pointed. Length 

 of case, -^ in. ; greatest diameter, T 3 g in. In the specimen described the 

 pupal stage lasted from the 10th August till the 1st October — that is to 

 say, sixty-one days. Only one was obtained, and its puparium was almost 

 as large as the pupa of its host, from which it had emerged by bursting 

 through the head. On one occasion at least fifteen imagines were reared 



In all other cases observed a single host has reared but one parasite. 



