Under side, male, marked as in fig. 3; border of red spots.
Female, almost exactly like that of Corydon (fig. 2 _a_), but usually has the black spots on the front wing smaller.
This is a most lovely little butterfly, the blue of its upper surface being quite unapproachable among native insects. Mr. Stainton, speaking of the different blues of Corydon and Adonis, happily observes that, "_Corydon_ { 157} reminds one of the soft silvery appearance of _moonlight_, whilst _Adonis_ recalls the intense blue of the sky on a hot summer's day."
The _butterfly_ is double-brooded, appearing first in May and again in August. It is found on the same soils and in most of the localities with the last, but is, I believe, more confined to the south.
(Plate XIV. fig. 4, Male; 4 _a_, Female.)
_Colouring_:--Upper side, male, lilac blue. Female, purplish blue about the centre, brown towards the margins, but the proportions of blue and brown are very variable--sometimes all the wings have a border of orange-red spots, sometimes these are absent from one or both pairs of wings.
_Fringe_ in both sexes _white, uninterrupted by dark bars_.
_Under side_, male, marked as in fig. 4, and hardly to be distinguished from under side of male Adonis, except by the ground colour, which is paler and _greyer_ than in Adonis. Female, same pattern as male, but coloured with warmer tints--more like male Adonis. { 158}
This very pretty little insect is the blue butterfly one sees everywhere, abounding in meadows, on heaths and downs, and not at all confined to chalky soils, like some other "blues."
The _caterpillar_ is green, with darker stripe on the back, and white spots on each side. It feeds on Bird's-foot Trefoil and other leguminous plants.
The _butterfly_ is to be found almost constantly from the end of May to the end of September, being double-brooded.
THE SILVER-STUDDED BLUE. (_Polyommatus Ægon._)
(Plate XIV. fig. 5, male; 5 _a_, Female.)
_Colouring_:--Upper side, _male, purplish blue_ (rather deeper than that of Alexis), with a rather broad black margin. Female, dark brown, sometimes slightly tinged with blue, and bordered on the hind wings with dull orange spots; but these are often absent.
Fringe white, _not_ barred with black. Under side, _near the margin of the hind wings_, and between that and the orange border spots, are several _metallic spots, of a bluish tint_, whence the insect has its name of "Silver-studded." { 159}