"Face with somewhat projecting or loose scales, or with conical tuft. Palpi rough-scaled. Antennæ in male ciliated, rarely dentate or naked. Abdomen not crested, or with crests on two basal segments only. Fore-wings with areole double. Hind-wings with 8 anastomosing with cell from near base to beyond middle. (See Plate [II]., fig. 32 head, figs. 33 and 34 neuration of Hydriomena deltoidata.)
"A very large genus, principally characteristic of temperate regions in both hemispheres.—(Meyrick.)
There are twelve New Zealand species.
HYDRIOMENA GOBIATA, Feld.
(Cidaria gobiata, Feld. cxxxi. 2. Phibalapteryx simulans, Butl., Cist. Ent. ii. 506. Phibalapteryx undulifera, Butl., Cist. Ent. ii. 506. Phibalapteryx anguligera, Butl., Cist. Ent. ii. 507. Phibalapteryx rivularis, Butl., Cist. Ent. ii. 507. Scotosia gobiata, Meyr., Trans. N. Z. Inst. xvi. 70. Cephalissa gobiata, ib. xviii. 184.)
(Plate [VI]., fig. 43 ♂, 44 ♀.)
This insect has occurred plentifully at Wanganui and Wellington in the North Island, and is generally distributed throughout the South Island.
The expansion of the wings is from 1 to 1¼ inches. All the wings vary from pale ochreous to rather dull yellowish brown, sometimes very slightly tinged with green. There is usually a large number of fine, slightly waved, oblique lines arranged on both pairs of wings, very like the markings in Venusia verriculata (see page 53), both insects evidently having acquired this style of colouring for similar protective purposes. In many specimens the whole of the anterior portion of the fore-wings, a small area at the base of the hind-wings, and a band near the termen are much paler in colour than the rest. There is usually a very oblique elongate pale area near the apex, and an irregular dark spot considerably below the apex. The outline of all the wings is more or less distinctly scalloped.
The larva (according to Mr. Purdie[[27]]) is about 1 inch in length, greyish-brown, with a rough prominent dorsal tubercle about the ninth segment. There are sometimes other smaller tubercles. It feeds on various species of Coprosoma in January, March, and May.
The perfect insect appears from October till March, and generally frequents rather open country where Manuka and Cabbage Tree Palms are abundant.