This butterfly is figured on Plate 120. The male is black, with three transverse tawny bands on the fore wings; these are crossed by the black veins, and so form series of irregular spots. Those on the outer margin have black centres; on the hind wings there are three or four tawny spots on the disc, and a series of black centred tawny spots on the outer area. The female is similar to the male, but the tawny markings are wider, so that the fore wings appear to be of this colour, with a black patch at the base, two black irregular lines, and a series of black spots on the outer margin. On the under side of the hind wings there are two transverse series of whitish spots, and a series of black spots on the outer margin. The wings of this sex are always broader than those of the male, and the apex of the fore wings is not so distinctly pointed. Variation is not usually of a very pronounced character, and in a general way it consists mainly in a greater or lesser amount of black in the male, and this more particularly on the hind wings, and an increase in the tawny colour in the female; in the latter sex, outer marginal black spots are sometimes absent from all the wings. Barrett mentions two extreme aberrations. In one, a female, the usually dark spaces, bands, and veins are of an exceedingly pale brown, suffused with fulvous, so as to be comparatively indistinct; another example, a male, has the basal area of the fore wings pale, and the first transverse dark band absent. [Illustration: _Pl._ 118. 1, 3 =Common Blue vars.=, _male_; 6 _do. female_. 2, 5, 8, 11 =Adonis Blue vars.=, _male_; 4, 7, _do. female_. 9, 10 =Chalkhill Blue vars.=, _female_; 12 _do. male_.] [Illustration: _Pl._ 119. 1, 2, 3 =Small Copper vars.=; 4 =Adonis Blue var.= 5 =Common Blue var.=; 6, 7, 8 =Gatekeeper vars.=] The eggs of this species are to be found at the end of May on the under sides of the leaves of the cowslip (_Primula veris_), sometimes as many as ten on one leaf, but as a rule there will only be one or two on a plant. When laid, the egg is very glassy in appearance, but it gradually turns to a pinkish-grey; and when the caterpillar is formed inside, the shell becomes transparent, and its occupant can be clearly seen. It eats a considerable portion of the shell in making its exit therefrom, and afterwards consumes the remainder of the shell. When in its last skin the caterpillar is brown, covered with short whitish hair, among which are some longer dark brown or blackish hairs; the lines on the back and sides are blackish, and there are black dots on the front part of each segment or ring. Head, honey brown, notched on the crown; eyes and jaws, brownish. It feeds from June to August on cowslip, but will also eat primrose (_Primula vulgaris_), and hides among dead and withered leaves beneath the food-plant (Plate 121).