2g8 
PIERIDAE 
fine longitudinal keels running from the crown to the base ; 
the intervening spaces are concave and transversely fluted by 
about forty fine ribs. When first laid, the colour is a rich 
cream-yellow, but to the naked eye the whole batch appears 
a bright primrose-yellow, making it very conspicuous when 
on the upper surface of a dark green cabbage leaf. When 
three days old, the colour is a clear citrine-yellow, the crown 
whitish and semi-transparent. The eggs remain this same 
colour until about thirty hours before hatching, and finally 
become opaque, with a leaden-coloured crown caused by the 
dark head of the larva showing through the shell. As soon 
as hatched, the young larvae feed upon the empty shells, 
leaving only the base, which forms their first meal; they 
then spin a layer of silk over the surface of the leaf and live 
thereon, and feed in company, eating first the cuticle of one 
side only, but after a short time they perforate the whole 
substance. They usually rest side by side, closely packed 
together. 
Larva. The larva becomes fully grown after the fourth 
moult and when thirty days old, when it then measures 
about 41 mm. in length. The colouring of the body is grey- 
green, darkest above, with three gamboge-yellow longitudinal 
stripes, one dorsal and one down each side; the ventral 
surface is greenish-ochreous; the claspers amber-ochreous 
blotched with brown. The head is black with a light-grey 
patch on each side of the crown. Over the whole surface of 
the body is a transverse series of shining black, short-pointed 
tubercles, each situated on a conspicuous black blotch, greatly 
varying in size, some being extremely small, but each bearing 
in proportion to its size a hair, some white and others black. 
The larvae are gregarious through all the stages, and have 
a curious habit of all resting and feeding at the same time, 
although they all spread out over the plant * the reason 
they all feed in unison in this way is unknown. In this, their 
last stage, they do not spin webs over the leaves. 
The fully-grown larvae select various places for pupation; 
the most usual being under some ledge, such as the copings 
of walls, palings or woodwork of sheds, and other timber 
buildings, when the pupa is attached in a horizontal position. 
Often it is fixed upright on window-frames, or tree-trunks, 
