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."
The caterpillar is brown, with white lines. Feeds on broom and other plants of the same order.