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 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., Trans. Ent. Soc. Lond. 1897, 385.)
This insect has occurred at Terawhiti in the North Island, and at Mount Arthur in the South Island.
The expansion of the wings is about 1-3/8 inches. The fore-wings are blackish-brown, darker towards the apex and termen; _there is an obscure rust-red wavy band near the base, and another at three-fourths, considerably bowed towards the termen at the middle_; there are also numerous wavy darker lines. The hind-wings are dull grey, and the termen is slightly scalloped.
This species may be distinguished from any of the varieties of _H. deltoidata_ by its _narrower wings, and the absence of any distinct central band on the fore-wings_.
The perfect insect appears in January. It is a scarce species.
(_Aspilates (?) subochraria_, Dbld., Dieff. N. Z. ii. 285. _Camptogramma subochraria_, Butl., Cat., pl. iii. 16. _Camptogramma strangulata_, Gn. x. 423. _Camptogramma fuscinata_, Gn., E. M. M. v. 92. _Arsinoe subochraria_, Meyr., Trans. N. Z. Inst. xvi. 73. Anachloris subochraria, Meyr., ib. xviii. 184.)
This species is fairly common and generally distributed throughout the country.
The expansion of the wings is about 1¼ inches. _The fore-wings are bright ochreous-yellow_; there is a brown dot a little above the middle, _and a dark brown transverse band at about three-fourths; the termen is shaded with dark brown_. The hind-wings are ochreous, with an obscure central transverse line.