PIERIDAE 
292 
Also, as the sun appears during sunshine and cloud, it is 
frequently seen rising from plants of Clover when not in 
bloom. Fields of Broad Beans are a great attraction to this 
butterfly, -owing to the honey-dew excreted by the bean 
aphis (Aphis rumicis ) over the leaves, on which A. cmtaegi 
settles to imbibe the sweet fluid. 
Egg Laying. In this country the eggs are laid in batches 
varying from 100 to 200, on Blackthorn, Hawthorn and 
different kinds of cultivated Plum. 
In a state of nature the eggs are, as a rule, deposited on the 
under surface of the leaves, otherwise heavy rain would dis¬ 
lodge them, as they are very easily detached. 
Egg. The egg measures -94 mm. high and -51 mm. wide. 
In shape it resembles an elongated acorn. It has fifteen 
(sometimes sixteen) longitudinal keels running from the base 
to the summit, where each terminates in a glassy globe 
enveloping an opaque white knob. The spaces between the 
keels are angular and very faintly ribbed transversely. The 
colour when first laid is a bright primrose-yellow and remains 
unchanged until a day or two before hatching, when the 
colour assumes a greenish-ochreous hue, and dark on the 
crown. The egg state occupies twenty-three days. 
Larva. After hatching, the little larvae remain for some 
hours all clustered together upon the empty egg-shells. After 
leaving the egg-shells, they spin a web over the surface of a 
leaf, living gregariously and all feeding on the same part of 
the leaf. For the first twelve days, they live exposed upon 
and under a slight covering of web ; they then spin a denser 
web, and all retire within it. They feed in relays numbering 
about one to two dozen individuals at a time ; they march 
out of the web together and feed in a row side by side, and 
retire in a body into the web. 
Hibernation. About the third week of October the larvae 
enter into hibernation. They hibernate in batches in separate 
compartments in a nest which is a tough, dense, silken mass 
of greyish-coloured silk spun over the remaining parts of the 
leaves upon which they feed, and around the branches, generally 
between a small fork. 
On February 16th, 1904, I examined one of the hibernacula, 
and upon cutting open one of the compartments, a little 
