100 BRITISH LEPIDOPTERA. 



does not offer any special difficulty. Imagine the larva twisted up 

 in its cocoon, its hairs flat on its body and all pointing in one 

 direction — i.e., towards the rear. If it advance, roll round, or 

 twist about, head forward, its hairs will always lie flat ; but if it 

 endeavour to go backwards its skin sticks up and its hairs will 

 be pushed against the walls of the cocoon, and all those that 

 happen to be opposite interstices will be pushed outside ; by 

 repetitions of these movements it will ultimately get rid of all of 

 them." He further notes that, in the neighbourhood of Paris, the 

 pupal stage lasts at least a month, the imagines emerging through the 

 whole of August. This is, of course, for the type. The pupal stage, how- 

 ever, even of the type is often extended to 1 3 months, that of the var. 

 callunae is normally 9-10 months, but frequently extends to 21-22 months. 

 Still longer pupal periods are on record, and one finds several 

 noticed also in a continental magazine (Enl. JVac/ir., v., pp. 218, 257 — 

 258, 285), e.g., a cf bred July 2nd, 1879, from a pupa of the summer 

 of 1876 (Stein), &c. 



Cocoon. — The cocoon is cylindrical, rounded at both ends, 

 composed of dense silk, intermixed with the short dorsal 

 fur of the larva, masses of the urticating hairs that form the 

 dorsal fur, often lying loose in the outer web by which the cocoon 

 is attached to the twigs, &c, among which it is spun ; they also 

 stand out directly from the cocoon proper, and hence careless 

 handling of the cocoon is almost sure to result in breaking off 

 some of the fine points in the skin. 1. Z. var. viburni: A cocoon ex- 

 amined (containing $ pupa) is 28mm. long and 14mm. wide, forms a 

 compact cylinder with rounded ends, rather brittle, pale yellow- 

 brown in colour, composed of closely felted silk with a paper-like 

 texture, some hairs on surface mixed with silk, some fine flossy 

 silk on outer surface of cocoon which forms means of attachment 

 to twigs, leaves, &c, among which larva spins up. The cocoon, on 

 being opened, is seen to consist of double walls, the inner of fine 

 whitish materia], wafer-like in appearance, but thin and papery in 

 texture, easily separated from outer coat, coming off in thin flakes. 

 A 2 cocoon of the same batch is 34*5mm. long, i5*5mm. wide, and 

 about i2'5mm. in thickness; the inner lining thinner and more papery 

 in texture than in $ cocoon. The cocoons of Z. var. meridionalis from 

 southern France are like those of L. var. viburni. 2. The cocoon of 

 L. quercits (English) [compared with that of Z. var. viburni] : Much 

 darker, softer, more silky as regards outer casing; 25mm. long, 

 i2 - 5mm. wide; tougher, thinner, less brittle; the inner wall not 

 peeling so easily from outer wall, also very thin, silky, less wafer- 

 like. 3. Z. var. callunae (Scotch) : Very large, 30-36mm. long, 15-1 6mm. 

 wide ; similar to those of English Z. quercus as regards quantity 

 and general appearance of inner lining, but of closer texture, and 

 harder externally. [Possibly the paler colour of the cocoons of the 

 southern (French) forms is due to a drier atmosphere, for some cocoons 

 of L. hybr. bacoti, allowed to pupate in glass jar instead of the ordinary 

 cardboard box, are quite as dark as the cocoons of Z. var. callunae. \ 

 (Bacot). 4. Reaumur describes the cocoon of Parisian quercus as: 

 "Brown, its exterior apparently smooth, but bristling with stiff 

 hairs to the touch ; an elongated ellipsoid in shape, almost cylin- 

 drical, with the ends rounded." 5. Andrews notes (E. JU. J/., 



