﻿112 [October, 



" The clean white silken cocoon is semi-transparent, and of a texture which 

 " strongly reminds one of the skin immediately beneath the shell of an egg, only 

 " that the silk is less opaque : it is placed among the twigs towards the centre of 

 " the branch, but not attached to them, although the webs of the larvae among 

 " the frass, and also of the numerous spiders which it contains, prevent the possi- 

 " bility of shaking it out : in spite of this, however, it is always quite clean." 



On the 18th of April, 1869, Mr. de Grey kindly sent me several larvse with their 

 food — that is to say, a mixed mass of birch twigs, decomposed leaves and earthy 

 matter containing many old cocoons and pupa cases, some small tufts of sheep's 

 wool, and an old gun wad. 



I separated this mass to look for the larvae, but found that they immediately 

 began again to construct loose silken galleries and thus re-united the various 

 materials of which it was composed. 



At this date the youngest larva was about half-an-inch long, of a dull pale 

 brownish olive-green ; others were larger and darker, the colour darkening with 

 the growth, until the full grown larva was almost black. 



When full grown, the length is from ly 1 ^ to 1£ inch ; the form moderately 

 slender, cylindrical, nearly uniform in bulk throughout, the hinder segments 

 tapering a little at the sides ; the region of the spiracles puffed and wrinkled ; the 

 segmental divisions deeply cut. 



The colour of the back is a blackish, bronzy-green, becoming paler, of an olive 

 or ochreous-green tint along the spiracles, and on the belly and legs, the head, and 

 the 2nd and 13th segments ; the plate on the second segment is margined in front 

 with blackish olive : a fine blackish undulating line, apparently caused by a deep 

 wrinkle, runs along below the spiracles, which are inconspicuous, being of the 

 surrounding colour, and merely outlined with blackish ; the tubercular dots are a 

 little raised, each bearing a fine hair ; the whole surface is shining and bronzy 

 looking. 



The first mature larva spun its cocoon on the 23rd of April, 1869 ; the cocoon 

 at first was soft and very flexible, of a brilliant silvery whiteness, its yielding sur- 

 face readily betraying the movements of the larva within, but after a day or two, 

 enough silk had been spun to make it firm and unyielding ; its length is about 

 | -inch, its breadth f ; in shape it is rounded at either end, very convex on both the 

 upper and under surfaces, these curves not being continued round the sides, but 

 meeting there in an acute ridge. 



The imago makes its exit at one end, but the edges of the orifice close together 

 again, and the pupa skin remains in the cocoon, which shows no change whatever 

 in appearance. 



The pupa is brown in colour, nearly half-an-inch long, stoutest at the thorax, 

 and diminishing in the ordinary way to the anal point, which ended in a short 

 spike. The old larva skin, though much shrivelled, showed it had been separated 

 on the crown of the head and down the back, and was left in contact with the 

 spike of the pupa. 



The moths appeared on the 6th and 11th of July. — Wm. Buckler, Emsworth. 



