At once the commonest and the handsomest of the Hair-streaks, being found in almost every part of England where there is an oak wood, and looking like a small Purple Emperor, with its rich gloss of the imperial colour.
The male has all the wings, in certain lights, of a dark brown colour, but with a change of position they become illuminated with a deep rich purple tint, extending over the whole surface excepting a narrow border, which then appears black. The female has the purple much more vivid, but confined to a small patch extending from the root to the centre of the front wing. Beneath, the wings are shaded with greyish tints, crossed by a white line on each wing, and having two orange spots at the inner corner of the hind wing.
The caterpillar ([Plate I]. fig. 9), which feeds on the oak, is reddish brown, marked with black.
The chrysalis, which is sometimes attached to the leaves of the oak, and at others is found under the surface of the earth at the foot of the tree, is a brownish object, of the lumpy shape shown in [Plate I]. fig. 28 (a form shared by the chrysalides of all the Hair-streaks).
The butterfly is seen in July and August, flitting about in sportive groups round oak trees, and occasionally descending within reach of the net. It also affects other trees besides oaks, some thirty or forty at a time having been seen gambolling about one lime tree. It being so generally distributed, it will be needless to particularize its localities.
THE GREEN HAIR-STREAK. (Thecla Rubi.)
([Plate XII]. fig. 5.)
This pretty little species is at once known from all other English butterflies by the rich bright green colour that overspreads its under surface. Above, the wings are deep, warm brown.