40 THE BUTTERFLIES OF THE BRITISH ISLES. 



Fig. 3 represents a male which certainly seems to be referable 

 to the spring form. Most authors give sabelliccE as belonging 

 to the summer flight, but this does not seem to be correct. 



Var. naftcecB is a large form of the summer brood, occurring 

 commonly on the Continent, in which the veins on the under 

 side of the hind wings are only faintly shaded with greenish- 

 grey. Occasionally specimens are taken in this country in 

 August, which both from their size and faint markings on the 

 under side seem to be referable to this form. 



Var. bryonice is an Alpine form of the female, and in colour 

 is dingy yellow or ochreous, with the veins broadly suffused 

 with blackish grey, sometimes so broadly as to hide the greater 

 part of the ground colour. This form does not occur in any 

 part of the British Islands, but some specimens from Ireland 

 and from the north of Scotland somewhat approach it. 



All the early stages are shown on Plate 10. 



The egg is of a pale straw colour when first laid, but it soon 

 turns to greenish, and as the caterpillar within matures, the 

 shell of the egg becomes paler. The ribs seem to be fourteen 

 in number. 



The eggs are laid singly on hedge garlic {Sisymbrium 

 alliaria) and other kinds of plants belonging to the Cruciferae. 

 The egg in the illustration was laid on a seed-pod of hedge 

 garlic, but the caterpillar that hatched from it was reared on 

 leaves of garden " nasturtium " and wallflower. 



The caterpillar when full grown is green above, with black 

 warts, from which arise whitish and blackish hairs. There is 

 a darker line along the back, and a yellow line low down on 

 the sides. Underneath the colour is whitish-grey. The 

 spiracular line is dusky, but not conspicuous, and the spiracles 

 are blackish surrounded with yellow. It has been stated that 

 caterpillars fed upon hedge garlic and horseradish produce light 

 butterflies, and that those reared on mignonette and watercress 

 produce dark butterflies. Barrett mentions having reared a 



