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REPORT ON THE NEUROPTEROID INSECTS OF THE HOT SPRINGS 

 REGION, N.Z., IN RELATION TO THE PROBLEM OF TROUT FOOD. 



By R.J. TiLLVARu, M.A.. D.Sc, F.L.S., F.E.S., Lixxeax Macleay Fkllow 

 OF THE Society ix Zoology. 



(With two Text-figures.) 



On arrival at Auckland from Sydney on November 5tli of last year, I was 

 met by Mr. D. Miller, Government Entomologist, and Mr. H. Hamiltoi., Zoolo- 

 gist to the Dominion Museum, and proceeded with them to Rotorua, where I met 

 Mr. Moorhouse, in charge of the Fish Hatchery in Lake Rotorua, and Mr. Hill, 

 Head of the Tourist Department. All these gentlemen offered me every assist- 

 ance in carrying out my investigations, and I desire to thank them very sincerely 

 for their aid. 



Three weeks were spent in the Hot Springs Region, the following' being the 

 itineraiy : — 

 Nov. 7tb-10th: Rotorua. Yisit(?d Te Wairoa, Whakarewarewa and portions of 



the Lake. 

 Nov. llth-17th: Te Wairoa and Lake Tarawera. 

 Nov. 18th-19th: Rotorua. Visited Fairy Spring, Hamurana Spring, Lake Ro- 



toiti and Okere Rapids. 

 Nov. 20th-21st : Wairakei and Taupo. 

 Nov. 22nd-26th : Tokaanu. 

 Nov. 27th : Lake Roto-Aira. 



Nov. 28th : Wairaarino. 



It was hoi)e<l that a return visit might have l)een arranged later in the seascm 

 (February) in order to see the other lakes and streams of this region, and to 

 study the insects in the height of summer. Circumstances, however, made it im- 

 possible to carry out this plan. 



The work done in the field may be divided into two parts : — 

 (i.) Examinations of the contents of trout-stomachs. 



(ii.) Collection of the larvae and imagines of Nenropteroid Insects from 

 the streams and lakes. 



' (i.) The Contexts op Trout-Stomachs. 



An examination of a considei'able number of trout-stomachs during the 

 month of November showed a great diversity of food eaten. The Green Mauuka- 

 Beetle, Pyronota festira, was found to be the most abundant food. This beetle 

 visits the Manuka bushes fringing the lakes and streams, and frequently falls or 

 is blown off into the water, when it is at once seized and swallowed by the trout. 

 Next in importance to this were found to be the larvae of the Caddis-flies of the 

 family Leptoceridae. which form their cases of the green weed Nitella. The 

 stomachs of a number of trout were found to be filled with this green weed, which, 

 on being placed in a basin of water was seen to consist entirely of caddis-fly 



