Hudson. — On Plume-moths. 379 



S. peroneanella. 



Four specimens last season, widely distributed in district, 

 being sometimes found in the heart of the city — at night-time 

 only — from about November to March. I have nine speci- 

 mens. 



S. picarella. 



Two specimens last season ; one taken outside a town shop- 

 window, attracted by the gaslight. I have only taken it in 

 November and December, and now possess three. 



Aet. XXXVII. — On the Unusual Abundance of Certain 

 Species of Plume-moths during the Summer of 1894-95. 



By G. V. Hudson, F.E.S. 



IRead before the Wellington Philosophical Society, 21st August, 1895.] 



The laws governing the relative abundance of different species 

 of animals and plants are so obscure, and at present so little 

 understood, that it is always desirable to record the appear- 

 ance of any species when it occurs in unusual numbers. 



Last summer I noticed that the three species of forest- 

 dwelling plume-moths (Pteroj^horus monos]}ilalis, P. lycosema, 

 and P. furcataUs) were phenomenally common here. Ptero- 

 phorus monospilalis, a pure-white species, one of the most 

 delicately beautiful insects we have in New Zealand, was 

 to be found in the utmost profusion, as many as three or four 

 specimens being disturbed from amongst the ferns and dense 

 undergrowth at once. Ptcrophorus lycosema, distinguished by 

 having a broad band of brown on the fore-wing reaching as 

 far as the end of the posterior digit, was also extremely 

 abundant, though not quite so common as P. monosjnlalis. 

 P. fureatalis, distinguished by having a broad band and both 

 dicfits of the fore-wings brown, was connnoiier than usual, 

 but much scarcer than either of the two preceding species. 



I have much pleasure in exhibiting series of all three 

 species before the Society this evening, and have mounted 

 them on a dark background in order that their extremely 

 elegant appearance may be seen to advantage. I ought per- 

 haps to explain that, as a rule, these three insects are not 

 very common — that is to say, one would not expect to meet 

 with more than one or tw^o specimens during a day's collect- 

 ing in a favourable localitv. 



