IX. THE MICROPTEEYGINA. 129 



HEPIALUS VIBESCENS, Dbld. 



(Hepialus virescens, Dbld., Dieff. New Zeal., ii. 284 ; White,. Taylor New Zeal., pi. i. 6. Hepinlus rubro- 

 viridam, White, I.e., pi. i. 1. Charagia virescens, Walk., Bomb., 1569; Scott, Trans. Ent. Soc. N. S. Wales, 

 ii. 28. C.fischeri, Feld., pi. Ixxx. 1. C. hectori, Butl., Proc. Zool. Soc. Lond., 1877, 380. He.pialus vircscens, 

 Meyr., Trans. N. Z. Inst., xxii., 211.) 



(Plate XIII., fig. 16 3 , 17 2 ; Plate III., fig. 23 larva, 30 pupa.) 



This large and conspicuous insect appears to be generally distributed throughout 

 the North Island. 



The expansion of the wings of the male is 4 inches, of the female sometimes fully 5* inches. 

 The fore-wings of the male are bright green, with a series of paler ring-shaped markings between 

 the veins ; an irregular row of white spots crosses the wing near the middle, and a small white spot 

 is situated on the costa at the base. The hind-wings are very pale yellowish-brown near the body, 

 becoming pure white in the middle, and pale green on the termen. The head and thorax are green, 

 the abdomen is white, tinged with green at the apex. The female has all the wings of a relatively 

 more attenuated shape ; the fore-wings are green, mottled with black ; the hind-wings are pale 

 reddish-brown, shaded with green near the termen ; the abdomen is also reddish-brown, becoming 

 green at the extremity. 



The species is rather variable in both sexes. In the male the white spots on 

 the fore-wings vary considerably in size, and there are occasionally several additional 

 spots near the body. In the female the black markings of the fore-wings are sometimes 

 much more extensive than the green ground colour. This dark form of the female 

 was described by Butler as a distinct species, under the name of Charagia hectori. In 

 both sexes the green colouring is occasionally entirely absent, a dull orange-brown 

 taking its place. I formerly attributed this peculiarity to the effects of fading, but 

 Mr. Norris has shown me a very perfect specimen of this variety, which he bred from 

 the pupa, he having noticed the orange-brown colouring immediately after the insect 

 emerged. 



The transformations of this insect are very interesting. The female lays an 

 enormous number of very small, round, yellowish eggs, which she seems to deposit 

 quite indiscriminately. The young larvae consequently have to find their way along 

 the ground to the stems of their food-plant, a large percentage no doubt perishing 

 before they succeed in doing so. and this circumstance probably accounts for the great 

 number of eggs produced. 



The food-plants of this species are numerous ; the following are a few of them : 

 " wine berry " or "currant" (Aristotelia racemosa), apparently the favourite ; "manuka" 

 (Leptospermum ericoides) ; " ki-ki " (Astelia solandri); "black maire " (Olea apeteld) ; 

 titoki (Alectryon excelsum) ; and Melicope. The larva tunnels the stems of these 

 trees, feeding entirely on the wood, which it bites off with its strong mandibles. 



For the most part it inhabits the main stem of the tree, its gallery always having 

 an outlet, which is covered w r ith a curtain of silk and refuse, and is spun exactly level 

 with the surrounding bark, and very inconspicuous. These burrows usually run 

 towards the ground, and are mostly two or three inches from the surface of the trunk. 

 In some instances the larvae inhabit branches, in which case, if they are small, the 

 tunnels are made near the centre. Later on in its life, but probably some time before its 

 transformation into the pupa, the caterpillar of this insect constructs a far more com- 

 plicated burrow than the above. It consists of a spacious, irregular, but shallow cavity, 

 just under the bark, having a very large opening to the air, which is entirely covered 



17 



