The eggs are laid in spring, by females that have hybernated throughout the winter, on various leguminous plants, including the lucerne (Medicago sativa), black medick (M. lupulina), purple and Dutch clovers (Trifolium pratense and T. repens), and the bird's-foot trefoil (Lotus corniculatus), and on these plants you may search for the larva, though it can scarcely be said that you are likely to find it.
The caterpillar is green, with black dots, and a yellowish stripe on each side. When fully grown it ascends a stem of its food plant and changes to a green chrysalis with yellow stripes.
Hyale is single-brooded in England, although two broods regularly appear on the Continent. In our country the perfect insects emerge during July and August. Many of these die before the approach of winter; but, as we have already observed, some hybernate and deposit their eggs in the following spring.
The Clouded Yellow (Colias Edusa)
Not only are this and the last species similarly named, but a glance at the figures will show that they much resemble each other in appearance; and we shall also learn presently that in their habits and life history they have much in common.
The male Edusa is shown on [Plate II] (fig. 3), and when we compare it with its relative on the opposite side, we are at once struck with the superior richness of the brilliant orange or saffron of the ground colour. The black border of both fore and hind wings is also denser, wider, and more extensive. The whole of the yellow area of the hind wings is dusted more or less with black scales, with the exception of a round central spot of deep orange, corresponding with the orange spots on the hind wings of Hyale.
The female, which is shown in the accompanying woodcut, is generally larger than the male, and is further distinguished by the very pale yellow spots that break the black border of both pairs of wings.