THE WOOD WHITE 
287 
flight. It may be found at rest upon foliage, but is somewhat 
difficult to detect owing to its form and colouring assimilating 
to its environment. 
Hibernation. The Wood White passes the winter as a 
pupa, in which stage it exists for about ten months ; but the 
pupae which produce the second brood remain only about 
eight days in the pupal state. 
Egg Laying. The eggs are laid singly on the under surface 
of the leaves of the Tuberous Pea (Orobus tuberosus). The 
egg stage lasts about eleven days. When intent on de¬ 
positing, the female flutters over the selected plant, settles 
on a leaf, then curves her abdomen over the edge and lays a 
single egg, and flies off to another plant to repeat the process. 
The egg is 1*30 mm. high. It is of an elongated conical form, 
attenuated at each end, mostly so at the summit, which 
terminates in a point; the base is rounded and firmly attached 
to the leaf by a short pedestal of glutinous substance. The 
egg is asymmetrical in shape as it curves slightly to one side. 
It has eleven longitudinal keels, the spaces between are 
delicately ribbed transversely by about forty-two in each 
space. The colour is a clear pale lemon-yellow and remains 
unchanged until shortly before hatching, when it assumes an 
ochreous hue. 
Larva. The little larva eats its way out of the egg and soon 
after emergence devours part of the empty shell. After its 
fourth moult the larva becomes fully grown and then measures 
19 mm. in length. In shape it is almost cylindrical and rather 
slender, gradually tapering at the tail, the last segment ter¬ 
minating in a flap overlapping the anal claspers. The colour 
is a bright clear green, and there is a darker green line running 
down the middle of the back, also a spiracular yellow stripe, 
bordered above by a darker green stripe, which blends into 
the ground colour of the side, but is sharply defined below and 
is in strong contrast to the yellow. The surface of the larva 
is finely granular and sprinkled with,minute pillar-like pro¬ 
cesses. The Tuberous Pea is its usual food plant in a wild 
state, but the larvae will readily feed on the Sweet Pea, 
Everlasting Pea and Garden Pea, also on Bird's Foot Trefoil 
(Lotus corniculatus) and other Leguminous plants. The larval 
stage lasts thirty days. 
