(Plate [V]., fig. 8 ♂, 9 ♀; Plate [III]., fig. 7, larva.)
One of the most abundant of our night-flying moths, occurring in great profusion throughout the country.
The expansion of the wings is about 1½ inches. The fore-wings are pale reddish-brown, darker towards the middle. There are two elongate, pointed, white markings touching the termen below the middle, and a central white streak, interrupted in the middle, by a small semicircular white mark, which represents the lower portion of the reniform spot; the orbicular and claviform spots are obsolete. The hind-wings are dark grey. The head and thorax are reddish-brown, and the abdomen is dark grey. The antennæ are serrate in the male but simple in the female. In some specimens the white markings are more extensive than usual, but otherwise there are no important variations.
The larva is bright reddish-brown; the dorsal stripe is broad and black; the subdorsal narrower, edged with white; the lateral lines are dull red, white, and black; the ventral surface, head, legs, and prolegs are greenish-grey with black markings; the spiracles are black.
This caterpillar varies considerably in the intensity of the light and dark markings. It feeds on grasses in January and September, and is very active. It often occurs in prodigious numbers, and at such times may frequently be seen travelling at a great rate over bare ground in search of food. Amongst the grass it is hard to detect, as the striped colouring is very protective in that situation.
The pupa state is spent in the earth, or under moss on fallen trees.
The moth appears from September till April. It is double-brooded. A few of the second brood emerge in the autumn and hibernate as moths, but the majority pass the winter in the pupa state. Hence we sometimes meet with specimens on mild evenings in the middle of winter.
This insect is much attracted by light, and occasionally assembles in vast numbers round a brilliant lamp. I have had as many as one hundred specimens in my verandah at Karori, attracted during two or three hours. It is by far the commonest insect at the collectors' sugar, the numerous visitors of this species eagerly jostling each other in their haste to obtain a share of the sweets. M. composita is likewise observed in the utmost profusion on attractive flowers of all kinds, crowding out the rarer and more aristocratic species. Mr. Hanify has drawn my attention to the remarkable habit this insect has of suddenly stopping during its flight, and thus eluding pursuit. It also takes wing with unusual rapidity. Specimens of this moth may constantly be observed at rest in various situations during the daytime, when the protective character of the colouring will be at once apparent, especially when the insect is partially concealed amongst grass. Mr. Meyrick informs us that this species is common in Tasmania and South-Eastern Australia.
MELANCHRA STEROPASTIS, Meyr.
(Mamestra steropastis, Meyr., Trans. N. Z. Inst. xix. 22.)