The Black Hairstreak (Thecla pruni), [Plate XII.], Fig. 5. —About the same size as the last, but many individuals are smaller. The ground colour is almost black, but near the tail are two or three conspicuous orange spots, which are not present in w-Album. The orange band on the under side of the hind-wing is much bolder and is edged with black spots on both sides, the inner row of spots being partially ringed with white; the white hairstreaks are fainter and slightly interrupted. This is the rarest of the group, and confined to a few localities in the South and South-East.
The caterpillar is green, with yellow spots and lines; it is found on Sloe and Oak. The perfect insect is out in July.
The Purple Hairstreak (Thecla quercus), [Plate XII.], Fig. 3. —The commonest and most widely distributed of the Hairstreaks extending well into Scotland where, however, it is not common. The upper surface in the male is shot with purple, while the female has a patch on either fore-wing of a still more pronounced sheen. The under side ([Plate XIV.], Fig. 8) is a cool grey; the "hairstreak" is white and strongly defined by an inner edging of dark brown. There are also two orange eye-spots near the tail, which in this species is rather small.
PLATE 14
1. Pupa of [Red Admiral]
2. Larva of [Red Admiral]
3. Larva of [Small White]
4. [New Small Skipper]
5. Pupa of [Small White] (showing hole through which ichneumons emerged)
6. Larva of [White Admiral]
7. [Brown Hairstreak] (under side)
8. [Purple Hairstreak] (under side)
9. [Ringlet] (under side)
The caterpillar is a reddish-brown and grey mixture, with a lighter angular pattern along the back, and a light line along the sides. It feeds on Oak.
I once came upon a small colony of this little butterfly flying round some Oak-trees in Argyllshire, but not one of them came lower than 15 feet from the ground, and after trying a variety of expedients I had to retire discomfited without a single capture. A visit to the same spot on subsequent days failed to reveal a single specimen. August was the month. In the South it is out in June.
The Green Hairstreak (Thecla rubi), [Plate XII.], Fig. 2. —The smallest of the British Hairstreaks and a fairly common species. Deep dingy brown above, bright emerald-green below, traversed by white hairstreaks, although in some specimens I have taken these white lines are absent. An elusive little butterfly, as when it settles amongst green herbage with the wings closed it is rendered almost invisible, so well does it harmonize with its surroundings.
The caterpillar is green, spotted and striped with yellow; it feeds on Bramble and Broom. The butterfly is out in June generally, but I have found it in the closing days of May in a favourable season. In the South a second brood appears in August. It reaches as far north as Perthshire, and is frequently met with in the West Highlands.