THYMELICUS ACTEON. 121 



eating out wedge-shaped portions from the side which cuts off the 

 pointed tip, leaving an oblique edge above, and also eating away other 

 wedge-shaped pieces from the side of the blade (Buckler). At Meseritz, 

 in nature, they feed on the small wood-reed, Galamagrostis epigeios, 

 chiefly under the shade of fir-trees, making deep notches in the edges of 

 the leaves which help to betray their proximity, feeding in the evening 

 and at night, and resting in the daytime extended along the flat 

 surface of the leaf (Zeller). They are fullfed from about the middle 

 of June onwards, when they spin their puparia (Buckler, June 

 23rd, 1873). Larva? have been taken many times in the spring and 

 early summer months in the Isle of Purbeck by Bankes, who notes (in 

 litt.) dates as follows :— May 27th, 1885; April 29th, 1890; May 

 26th, 1890; June 17th, 1892; May 7th, 1894, and June 7th, 1905. 



Larva. — Young larva: When young the larva is whitish-green 

 with green median longitudinal line, and black head ; later with 

 green lateral lines, red-brown prothoracic stripe and green head, 

 etc. (Riihl). Penultimate and Final instars: The larva is green in 

 colour in the penultimate instar (length 12* 5mm.), finely studded with 

 minute black skin-points, in the last instar (22mm. when stretched) 

 the skin-points are practically invisible except in front, but when 

 detected are seen to be mere white down or very fine hairs, at any rate 

 colourless or nearly so. These differences (of size and skin-points) are 

 the chief between the two stadia. In the penultimate the larva rolls 

 one or two blades of grass so as to form a tube, using a good deal of 

 white silk. One, wishing to moult and finding the grass too dry and 

 shrivelled, used the muslin cover, which it drew into a tube with chiefly 

 six strong transverse cables. The head has a slight fuscous tint, is 

 very rounded and minutely shagreened, and shows abundant very minute 

 hair-points. The colouring is in longitudinal stripes, but the elements 

 of these stripes are largely transverse yellow lines occupying the sub- 

 segments. No primary tubercles can be made out. There is a broad 

 dorsal stripe, green, the next line (narrower) being yellow, and it 

 has an indication of a faint yellowish line down its centre, the dorsal 

 line strictly speaking. The lateral line, some way below the pale fawn 

 and inconspicuous spiracles, is whitish, between the dorsal band and 

 the lateral line is first the yellow line bordering the dorsal stripe, and 

 some irregular green and yellow marblings, of which the yellow most 

 affects the two posterior subsegments and forms an intermediate line. 

 The effect is to make this region look less dark than the dorsal band. 

 Each abdominal segment is divided into an anterior (nearly) half, 

 which is indistinctly divided into two subsegments, and a posterior 

 (not quite perhaps) half, divided distinctly into four equal subsegments. 

 On the latter the black skin-points tend to form transverse rows, one 

 row and an imperfect row to a subsegment, on the front half they are 

 less regular. Round the posterior margin (behind anal plate) is a 

 fringe of white hairs, the only really definite hairs on the larva. The 

 underside is rather flattened, more apple-green than the upper, i.e., without 

 yellow. Final instar: In the last instar the striping is more definite and 

 less of a marbled character — a fine dorsal line, yellow, shading into broad 

 dark green stripes, then a greenish-white line, next a yellowish-green 

 band, then a narrow yellow line, then a broad space of pale green, in 

 the middle of which is the spiracle — followed by the whitish lateral line. 

 These lines seen dorsally do not converge much at hind extremity. The 



