Maskell. — On Psyllida? in New Zealand. 157 



Art. XVII. — On some Species of Psyllidae in New Zealand. 



By W. M. Maskell, F.E.M.S., Coit. Mem., Eoyal Society 



of South Australia. 



[Read before the Wellington Philosophical Society, 2nd October, 1889.] 



Plates X.-XII. 



The Psyllidce are a family of insects, of tiie order Homo- 

 ptera, more nearly allied to the Aphididce than to Coccididce, 

 though in many cases, where they are fixed and stationary in 

 their earlier stages, they exhibit niucli of the appearance of 

 the latter family — so much so, indeed, that sometunes close 

 examination only can detect the difference. They seem to be 

 cosmopolitan, but up to the present the European species 

 have been chiefly studied. Prom New Zealand, so far, no 

 species have been reported, but at least four or five appear to 

 exist here. Several entomologists in Europe have studied this 

 family since the time of Linnteus and Reaumur : the j^rincipal 

 modern authorities are Dr. F. Low, in Germany, and Mr. J. 

 Scott, in England. 



The Psyllidce are, in the adult state of both sexes, pretty 

 little four-winged flies, variously coloured. They are very 

 well adapted for leaping, whence they have derived their Greek 

 name, and also their trivial name of " leaf -hoppers." In their 

 earlier states they often exhibit colours and forms of singular 

 beauty. They live altogether on various plants, extracting 

 from these their food by means of a rostrum and setae, as do 

 the Aphides and Coccids. 



The Psrjllidce belong to the dimerous subdivision of the 

 Homoptera — that is, insects with two-jointed tarsi. They 

 may be further distinguished from Coccids by the presence of 

 four wings and a double claw in both adult sexes. The 

 different subdivisions of Psyllids are separated by systematists 

 on characters which are very minute and often difficult of 

 detection. Colour is to some extent taken into account, 

 although for my part I would lay very little stress upon this 

 (and the remark may extend to other orders of insects besides 

 Homoptera) ; for not only are there several variations in the 

 insects themselves, but I doubt whether any two men agree 

 exactly in the nomenclature and appreciation of colour : shades 

 of green and blue, of red and purple or violet, and so on, might 

 lead (and I think have led) entomologists into much diffuseness 

 of description and useless multiplication of species. There 

 are, however, several minute differences noticeable amongst 

 Psyllidce which are of greater value, and from the principal 

 amongst these the sub-families may be separated as fol- 

 lows : — 



