THE GREEN-VEINED WHITE 
309 
The butterflies of the second brood lay their eggs at once, 
and these produce autumnal pupae, which likewise emerge in 
the following spring. 
Hibernation. Like both P. brassicac and P. rapae , P. napi 
always hibernates in the pupal state, which extends over a 
period of eight or nine months. 
Egg and Egg Laying. The Green-veined White lays its 
eggs singly on the under surface of the leaves and young 
shoots of the various kinds of Cruciferac. Among those most 
commonly selected by the butterfly are : Charlock ( Sinapis 
arvensis ), Garlic-mustard (AMaria officinalis), Yellow Rocket 
(Barbarea vulgaris ), Watercress ( Nasturtium officinale ), Cuckoo 
Flower ( Cardamines pratensis) and Hedge Mustard (Sisym¬ 
brium officinale). 
The egg measures 1 mm. high and stands erect. It is 
of an elongated conical shape, with fourteen or fifteen 
longitudinal keels; except for five of these, they all run 
the whole distance from the summit to the base; the 
intervening spaces are transversely ribbed. The colour of 
the egg is pale yellowish-green and is glistening. The normal 
time of the egg state is about five days, but varies according 
to the temperature. 
Larva. After moulting four times, and when about sixteen 
days old, the larva attains full growth. It then measures 
25 mm. in length. In shape the body is slightly tapering at 
either end, being stoutest in the middle. The ground colour 
is a pale green, lightest on the ventral surface ; the head is 
also green. The spiracles are black, encircled with bright 
yellow, and there is a pale,indistinct spiracular line. The larva 
closely resembles that of P. rapae, but P.napi is a lighter green 
in colour and has no yellow line down the back, and the 
yellow markings are missing on the spiracular line, except 
for those encircling the spiracles. 
While crawling, the larva has a gliding, slug-like motion, 
and waves the head from side to side. The larval state 
occupies about eighteen days. 
Pupa. The pupa averages in length 19 mm.; it bears a 
close resemblance to that of P. rapae , but the abdomen is 
straighter, the sub-dorsal keel is less bi-angular, and the 
meta-thorax less sunken. The colouring is very variable, 
