The Clouded Yellow has been found hybernating in the chink of an old wall at the end of February, but I am not aware of its coming out again in the spring, like the Brimstone.
The ground tint of the wings is an exceedingly rich orange-yellow, or saffron colour, surrounded by a border of very dark brown, sometimes nearly black. This border is marked, in the male, with thin yellow lines, and in the female with paler yellow spots. There is a beautiful rose tint in the fringe of the wings and on their front edge. Underneath the wings are paler yellow, taking a citron hue in some parts, and marked with black and brown; in the centre of the under wings is a brown-circled silvery spot.
There is a peculiar and constant variety of the female, in which all the yellow portion of the upper surface is replaced by a greenish white tint; but in every other respect the insect agrees with the common form of Edusa. This interesting variety was formerly ranked as another species, under the name of C. Helice; but it is a curious fact that no corresponding variety of the male has ever been observed; and last year I captured a pair together—a white female and common orange male—who were on those terms of tender intimacy which are generally supposed to betoken identity of species.
Varieties of the female are also met with, of various intermediate shades of colour between the white and the ordinary orange.
Yet is it not possible that all these varieties may be mules between C. Edusa and C. Hyale (the next species), the males of which are often seen pursuing the lady Edusas? but if so, as indeed it would be on any other hypothesis, it is hard to account for the unvarying character of the male.
This butterfly is also called the Clouded Saffron.
THE CLOUDED SULPHUR, OR PALE CLOUDED YELLOW BUTTERFLY. (Colias Hyale.)
([Plate III]. fig. 4.)