The expansion of the wings varies from 1-1/8 to 1-3/8 inches. The fore-wings vary from brownish-black to dull orange-brown; there is a small darker area near the base, then two pale whitish wavy transverse lines, then a broad darker central band, often containing within it a still darker central band, bounded by two wavy black transverse lines; beyond the central band there are nearly always two or three pale brown or whitish, wavy, transverse lines, then an interrupted line just before the termen, and a short oblique whitish line below the apex; there is a black dot a little above the centre of the wing, and _a white dot on the termen near the middle_. The hind-wings are yellowish-brown, with several wavy, transverse lines near the dorsum; there is a series of fine crescentic black lines on the termen of both fore- and hind-wings. {48}This species is extremely variable, but may generally be recognised by a careful scrutiny of the above-named characters. One very striking variety occasionally met with has the central band of the fore-wing completely divided in the middle, which thus forms two dark patches, one on the costa, and one on the dorsum. (See Plate VII., figs. 7 and 8.) A further development of this variety, of which I have only seen one example, taken by Mr. Hawthorne at Springfield, Canterbury, and now in his collection, has only the costal patch present, the whole of the lower portions of the band being completely obliterated.[28] (See Plate VII., fig. 9.) The minor varieties are too numerous to specify. The larva feeds on grasses. When full-grown its length is about 1 inch. The colour is dark brown, with the skin very much wrinkled. It is sluggish in its habits, and lives through the winter, becoming full-grown about the end of September. During severe weather it generally seeks refuge from the elements amongst the stalks and roots of the rank herbage often surrounding stones or fallen logs. The pupa is concealed in the earth. The perfect insect appears early in January, and continues in the utmost profusion until the middle or end of March. It may often be seen resting with the wings folded backwards and forming together a triangle, whence the moth has probably derived its name of _deltoidata_. In the neighbourhood of Wellington I have observed that this insect has very much decreased in numbers during the last ten or fifteen years. HYDRIOMENA HEMIZONA, Meyr. (_Hydriomena hemizona_, Meyr., Trans. Ent. Soc. Lond. 1897, 385.) (Plate VII., fig. 10.) This insect has occurred at Terawhiti in the North Island, and at Mount Arthur in the South Island.