This species has occurred in the South Island at Mount Arthur, Castle Hill, and Invercargill.
The expansion of the wings is about 1⅜ inches. The fore-wings are dull white with an irregular, central, longitudinal, blackish-brown streak becoming very broad towards the termen; there is an oval reddish-brown blotch near the base, but no distinct transverse lines; two conspicuous elliptic, white marks are situated on the termen near the tornus. The hind-wings are pale grey, with an obscure central shade and a series of brownish dots along the termen.
The species appears somewhat variable. In some male specimens the white colouring is largely replaced by pale yellowish-brown. Described and figured from specimens in the collections of Messrs. Fereday, Hawthorne, and Philpott[[14]].
MELANCHRA INSIGNIS, Walk.
(Euplexia insignis, Walk., Suppl. 724. Xylina turbida, ib. 754. Mamestra polychroa, Meyr., Trans. N. Z. Inst. xix. 16. Mamestra insignis, Meyr., ib. xx. 45.)
(Plate [IV]., fig. 29 ♂, 30 ♀.)
This pretty species has occurred at Palmerston and Wellington in the North Island, and at Blenheim, Christchurch, and West Plains near Invercargill in the South Island. It is probably common and generally distributed.
The expansion of the wings is about 1⅜ inches. The fore-wings are pinkish-brown; there is a short black streak near the centre of the wing at the base, and an irregular, extensive black marking along the dorsum; the orbicular, reniform, and claviform spots are large, margined first with green and then with black; a fine white line is situated parallel with the termen, edged with green, and emitting two sharp tooth-like markings; beyond this line the ground colour of the wing is dark-brownish-black. The hind-wings are dull brown, darker towards termen; the cilia are white with a brown line. The antennæ of the male are slightly bipectinated. In the female the ground colour is considerably paler, the black markings much darker, and more suffused, and the posterior half of the reniform is usually creamy-white.
Some specimens have the green and black markings slightly more pronounced, but otherwise there are no important variations.
The eggs are deposited in October and November. When first laid they are pale greenish-white, but become dark brown in the centre as the enclosed embryo develops. The young larvæ emerge in about a fortnight. At this time the two anterior pairs of prolegs are very short, causing the caterpillar to loop up its back when walking. In colour the young larva is pale brown, with numerous black warts emitting several long, stiff bristles. It is very active, and busily devours the soft green portions of the dock leaves, leaving the harder membrane untouched. Twelve days later the larva becomes pale green in colour, and moults for the first time, after which traces of subdorsal and lateral lines present themselves. Growth then proceeds with great rapidity, and in another eleven days the larva again sheds its skin. The last moult occurs a fortnight later.