Volume 10, Plate XXVII / Entomology (Insects)

Brown & Purple Hair-Streaks

Thecla Betulæ & T. Quercus

1. & 2. Brown Hair-Streak. Largest of the British hair-streaks, spanning some eighteen lines, it is dark brown with a silky gloss, the female bearing a large kidney-shaped orange patch on the fore wings. Beneath it is entirely tawny-yellow with two white undulating lines; its green caterpillar feeds on birch and blackthorn, and the fly, scarce here though common abroad, appears about early August.
3. & 4. Purple Hair-Streak. Smaller than the brown hair-streak, it is dark brown, one sex faintly glossed with purple, the other with a large patch of deep glossy blue at the base of the fore wings. Beneath it is ash-grey with a white streak and fulvous spots; its greyish-brown caterpillar feeds always on oak, and it is the commonest Thecla, abundant in southern oak woods.