128 THE BOOK OF BRITISH BUTTERFLIES. 



The eggs are laid in July on the Sallow or Goat 

 Willow (Salix Caprea), and possibly on the Poplar and 

 the Oak. They hatch in about a week-and-a-half, and 

 the larvae feed till the autumn, and then hibernate 

 when about in. long, fastened with silk in a fork of the 

 food -plant, where they much resemble a small twig. 

 Whe"n leaves reappear on the Sallow, they commence 

 feeding again, and are full-fed at the end of May or 

 the beginning of June; the chrysalis may be found in 

 the latter month, and the imago in the next. 



The handsome larva (Fig. 131) is, when full-grown, 

 about 2 in. in length. The tapering body and the horns 

 on the head give it a very slug-like appearance, and the 

 resemblance is heightened by the way the body contracts 

 when the animal is annoyed. The dorsal surface is 

 bright green ; the ventral surface, legs, and claspers 

 are bluish -green. The segments are subdivided into 

 sections, each of which bears a row of yellow points. 

 There is a yellowish stripe on each side in the region 

 of the spiracles, which are pink. On each side also are 

 seven oblique yellow stripes edged posteriorly with pink, 

 the third pair almost meeting on the back. The two 

 horns are green, brownish at the tips, and bluish in front. 

 A whitish line passes down them behind, and extends 

 through several segments along the back. 



The pupa (Fig. 130), which is suspended from the 

 midrib of a leaf of the food-plant, is without angles or 

 spines. It is whitish-green in colour, all the edges being 

 marked with even lighter lines. The wing-cases, too, are 

 veined with the lighter colour. There are two short 

 anterior horns, with dark tips, and the oblique lateral 

 lines of the larva are repeated in a whitish tint on the 

 pupa. It is liin. or more in length, about Mn. from 

 back to front, but only about iin. through from side to side. 



