The egg (Plate [15]), when freshly laid, is whitish, faintly tinged with greenish; it soon changes to yellow, and, later on, turns orange and then dark violet. When the latter colour appears, the little caterpillar may be expected to hatch out very shortly. The eggs are placed upright on the foot-stalks of the flowers, and may be readily found in June by searching the blossom-clusters of hedge-mustard or cuckoo-flower.
The caterpillar, when mature, is dull bluish-green, with raised dots and warts; from the former arise whitish hairs, and from the latter longer blackish hairs. There is a white line, or stripe, along the sides, and the underparts of the body are greener than the back. Both in colour and marking the caterpillar agrees so closely with the seed-pods of its food-plant that its detection is not always easy. A peculiarity in very young caterpillars of this species, and also those of some of the "Whites," is, that the hairs are forked at the tips, and bear globules of moisture thereon (see figure and remarks on p. 3).
Larger Image
Pl. 14.
Green-veined White (Irish).
1 male; 2, 3 female.
Bath White.
4, 5 male; 6 female.