Figures of the butterfly will be found on Plate 105, and of its life history on Plate 104; the upper egg is that from a typical female, and the lower one was laid by a female _artaxerxes_. The egg, which is whitish, with a faint greyish tinge, is laid on the upper side of a young leaf of the rock-rose (_Helianthemum chamæcistus_). The caterpillar has a black shining head; the body is green with whitish hairs, a pinkish line along the back, a whitish one bordered with pinkish along the sides; the green colour becomes dingy as the caterpillar matures. The chrysalis is obscure yellowish-green, the front of the thorax is edged with pinkish, and there are bands of the same colour on the back and sides of the body; the thorax and the wing-cases are rather glossy. Held in position by a few silken threads between leaves of the food-plant. The ordinary form of the butterfly is on the wing in May and June, and again in August. It is widely distributed throughout the southern half of England, and also in Wales. Although chiefly associated with rock-rose, especially in chalky districts, it occurs too among stork's-bill (_Erodium cicutarium_), upon which plant the caterpillar also feeds, in sandy places inland as well as on the coast. Caterpillars from the first flight of butterflies may be found in July, and those from the second flight hibernate and feed up in April. The butterfly has a marked liking for roosting on the flower stems of long grasses, and quite a number may often be found resting together towards sundown, or on dull days, in sheltered hollows. Sometimes several specimens of this species and of the Common Blue may be found on the same perch. It is rather less frequently seen in the Midland counties, but it is more or less common in some parts of Derbyshire, Yorkshire, and Lancashire. [Illustration: _Pl._ 106. =Common Blue.= 1, 2, 7, 10, 12 _male_; 3, 4, 5, 6, 8, 9, 11, 13 _female_.] [Illustration: _Pl._ 107. =Common Blue.= _Eggs, natural size and enlarged; caterpillars and chrysalids._] The intermediate form, _salmacis_ and its modifications, is found in the neighbourhood of Richmond, Yorks, and thence northward to the Scottish border. Var. _artaxerxes_ occurs in Scotland from Roxburgh to Aberdeenshire on the east, and from Dumfries to the Clyde on the west. Kane records four specimens from Co. Galway, and these are all that are known of the species from Ireland. This form, together with the var. _salmacis_, are not found anywhere outside the United Kingdom, and, it may be added, the latter appears to be getting scarce--at least, in some of its old haunts in Durham. The species is distributed throughout the Palæarctic Region, except the Polar parts. The Common Blue (_Lycæna icarus_).