PLATE XI1. Chalk-hill Blue2. Little Blue
PLATE XI
1. Chalk-hill Blue2. Little Blue
You cannot possibly mistake the male of this butterfly for any other insect, for the upper surface of both its front and hind-wings is of the most beautiful silvery greenish-blue colour, shading off into a blackish band along the hind border. In fact, as a great naturalist once said, it always makes one think of a bright moonlight night, while the “Clifton blue” reminds one of the sky on a clear summer’s day. But the female is so exactly like that of the “Clifton blue” that it is hardly possible to tell the one from the other.
This lovely butterfly is hardly ever found except on chalky downs, and is commonest in the south of England. It flies in July and August. If you want to find the caterpillar, you must look for it in May and the early part of June. It feeds upon bird’s-foot trefoil and kidney-vetch, and looks rather like a fat little green woodlouse, with six yellow stripes upon its back and sides; and if you look at these stripes closely, you will see that they are really made of rows of tiny yellow spots. About the middle of June it fastens itself to the stem of its food-plant by spinning a silken band round its body, and then turns into a greenish-brown chrysalis.
This is a very tiny insect indeed. In fact, it is by far the smallest of all our British butterflies, and you might easily pass it by, over and over again, without noticing it, for it is not at all brightly coloured. The female is dark brown above, without any orange spots on the hind-wings, and even the male has only a faint tinge of blue in the middle of his wings. Underneath, both male and female are plain greyish-drab, with rows of tiny black spots enclosed in whitish rings. So you will have to look for it very carefully indeed if you want to see it. It is double-brooded—that is, it makes its appearance twice in the year, first in May, and then again in August. And you may see it flying about in meadows and on heaths, more especially in chalky or limestone districts.
The caterpillar of this odd little butterfly, like that of the chalk-hill blue, is shaped like a tiny woodlouse, and is green in colour, with an orange stripe running along its back, and another on each side. It feeds upon kidney-vetch, or “woundwort,” as it is sometimes called, and turns into a little yellow chrysalis, marked with three rows of black spots.
This butterfly is sometimes known as the Bedford Blue.