THE EGGS OF SOME BRITISH BUTTERFLIES 33
tail, or with vertical ribs as in that of the Small Tortoiseshell, or
again, covered with a raised hexagonal network as in the eggs of
the Blues; but the photographs will show the shapes and
markings better than they can be described.
The Large White (Pieris brassicae). I watched a female of
this species ovipositing and noticed that she travelled along the
rows of cabbages backwards and forwards, examining a plant
here and there, sometimes visiting the same plant several times:
at last she selected a leaf which was almost vertical and resting
on the underside, raised her wings over her back and, bringing
the end of her abdomen under her body, placed the first egg.
She then rested for a short time before feeling for the first egg
and placing the second by its side; this process was repeated
each time an egg was laid. The actual time taken to place the
egg was four seconds and the rest period was 11 seconds; during
the rest period the abdomen was straightened out into the normal
position. She deposited 48 eggs and was then disturbed by a
Small White which kept flying close to her. I do not know the
number of eggs this butterfly will lay, but I collected 10 batches
from these cabbages and found that the number in the batch
varied from 27 to 88, the average being 54; but of course a
butterfly will lay more than one batch. The eggs are generally
laid on cruciferous plants, being placed in regular batches on the
upper or lower surface of the leaf. They are 1.2mm. high, bottle
shaped, with about 18 longitudinal ribs and with fine cross
ribs, yellow when first laid. They hatch in about 10 days. (Fig. 1.)
The Small Tortoiseshell (Aglais urticae). When about to
oviposit, this butterfly selects the underside of a stinging-nettle
leaf and, resting upon the upper surface in such a position that
the abdomen can be curled under the leaf and with wings partly
expanded, she deposits her eggs, the wings vibrating slightly all
the time. The eggs are placed in a heaped-up mass and are of
a more or less cylindrical shape, 1mm. high and 0.8mm. in
diameter; they have nine vertical ribs. When first deposited
they are a pale green in colour and they hatch in about 10 days.
(Fig. 2.)
The Brown Hairstreak (Thecla betulae). This butterfly usually
selects a small bush of sloe upon which to deposit her eggs, which
are placed in the fork of a small branch; only one egg is placed
in each fork. They are 0.7mm. in diameter and 0.4mm. high,
and the markings are similar to those of the Purple Hairstreak;
the colour at first is white. The eggs are laid in August but do
not hatch until the following March. (Fig. 3.)
The Purple Hairstreak (Thecla quercus). The eggs of this
insect are placed singly on oak, either at the base of a dormant
C