210 BKITISH LEPIDOPTERA. 



tary canal is characterised by its being of a green tint in front and 

 yellow behind. 



Cocoon. — The cocoons average 3 mm. long and 2-2 mm. wide. 

 They are roughly oval in outline, and neither end is markedly wider than 

 the other. Each is regularly domed from the edge to the centre, 

 composed of a rather dark brown-coloured silk, becoming more yellow 

 round the outer rim ; the surface is comparatively smooth and rather 

 shiny, there being very little loose silk noticeable, except along the 

 somewhat crenate margin, by which the cocoon is generally attached 

 to the under surface of a leaf. [Described under a two-thirds lens, 

 on June 21st, from cocoons sent by Mr. W. H. B. Fletcher.] One 

 cocoon of this species, placed on the underside of a leaflet of R. semper- 

 virens, in which are the mines sent by Mr. Fletcher for description, 

 is of a pure white colour. It is placed partly under the slightly 

 curled margin of the leaf, and has a projecting pupa-case. There 

 is a considerable amount of loose flossy silk and a rather broad white 

 flange running around the outer edge. Other cocoons are testaceous, 

 and others, again, orange-brown in colour, mostly spun on 

 the under-side of a leaf, in the angle between the mid-rib and 

 a lateral vein. De Geer states that he examined the branches 

 and stems of the rose-trees, in the leaves of which he observed 

 empty galleries, in order to find the ordinary and natural retreats 

 of these insects. He found several enclosed in cocoons, which were 

 generally placed in some cavity or fissure in the bark of the branches. 

 He often found them " in the angle formed by two branches, or in the 

 angle formed by a large thorn with the branch from which it sprung. 

 The caterpillars choose such places because they find it easier there to 

 fix all round their body the threads which form the cocoon ; a level 

 surface would not have been so suitable." De Geer farther describes 

 the cocoons as " oval and white. In some, the white inclines to yellow. 

 Although their sides are thin, they are close and very strong, so that 

 one can hardly tear them without hurting the insect they contain." 

 Lewis describes the upper part of the cocoon as ' ' convex and generally 

 circular ; the under part oblong, shaped to hold the pupa, and much 

 smaller than the upper, which projects considerably beyond it on all 

 sides." Stainton writes : '• When full-fed, the larva splits the upper 

 skin of the leaf and creeps out ; and if it be the summer brood, 

 the larva proceeds to the foot-stalk of the leaf, and there spins 

 its orange cocoon, which is rather of a peculiar structure, for the 

 side of it exposed to the weather is found to have a sort of 

 outer covering, which projects beyond the limits of the actual cocoon, 

 serving, we may suppose, as a protection from wet. If the larva be 

 of the autumnal brood, it very rarely seeks the foot-stalk of the leaf, 

 but attaches itself to the main stem of the rose-bush, beneath the 

 shelter of some branch or thorn (or else it probably seeks shelter on 

 the ground among leaves). After completing its cocoon it assumes 

 the pupal state, in which it remains for a fortnight or three weeks in 

 summer, and for six or seven months in winter, at the end of which 

 time the pupa protrudes its head from one end of the cocoon, and the 

 imago emerges." 



Pupa. — The pupa is of a bright yellow-orange colour, in which the 

 parts of the future animal are more marked than in ordinary 

 " chrysalides." yet less so than in " nymphs." The form of the pupa 



