DODONIDIA HELMSI, Fereday.
(Dodonidia helmsi, Fereday, Trans. N. Z. Inst. xv. 193.)
(Plate [XI]., fig. 14, fig. 15 under side; Plate [III]., fig. 5 larva, fig. 28 pupa.)
A single specimen of this interesting butterfly was discovered by Mr. R. Helms, in 1881, on the Paparoa Range, near Greymouth, at an elevation of about 1,500 feet above the sea-level. Until within the last three years only three other specimens had been captured, viz., one near Wainui-o-mata, in Mr. A. P. Buller's collection; one on the Dun Mountain, Nelson, at an elevation of about 2,500 feet, which is in my collection; and one on the Tableland of Mount Arthur, at about 3,300 feet, which was kindly given to me by Mr. C. W. Palmer. In the summer of 1894-95 several specimens were captured by Mr. P. Marshall near Wanganui,[[53]] and during the same season Messrs. Smithers and Hawthorne discovered the insect in considerable abundance at a locality near Silverstream, in the Wellington district. During the two following summers additional specimens were obtained near Silverstream, and I was fortunate enough to discover there a number of specimens of the larva, which furnished the material for the illustration and description of the preparatory stages of the insect given in this work.
The expansion of the wings is about 2 inches. On the upper side all the wings are dark brown. The fore-wings have two broad bands of yellowish-orange, the outer one containing a small patch of dark brown near the costa, which touches a white-centred black ocellus. The hind-wings have one large patch of yellowish-orange containing two ocelli; a large ocellus, surrounded by a broad ring of reddish-orange, is situated on the tornus; the tornus is produced into two very broad but short tails, which are bordered with white cilia. On the under side the fore-wings are light ochreous-yellow; there is a shaded brown patch at the base; the termen is broadly bordered with brown, the border containing a silver streak; two broad brown patches are situated on the costa, the outer one terminated by a small ocellus, and enclosing a silvery patch near the apex of the wing. The hind-wings are silvery, narrowly bordered with deep reddish-brown, with five deep reddish-brown stripes running from the costa towards the tornus; the fourth stripe from the base of the wing contains three ocelli surrounded by yellow rings; a conspicuous ocellus is situated at the tornus, surrounded by a broad orange-red ring.
This insect appears to vary a little in the extent of the yellowish-orange colouring of the upper side. It also varies in size, specimens from the North Island being slightly larger than those from the South Island.
The larva feeds on a species of sedge (Galinia setifolia), which always grows abundantly in the birch forests, where the butterflies are found. When full grown the length of this caterpillar is about 1¼ inches. Its body is much attenuated at each end and rather stout in the middle; the head and tail are bifid; there are numerous straight, shallow, transverse wrinkles on each segment, especially towards the head. The colour is green, with a number of fine, paler and darker green, dorsal and lateral lines; the head and thirteenth segment are yellowish. The legs are very minute, and the prolegs of moderate size. It is extremely susceptible to the attacks of a Dipterous parasite. In fact, out of thirty larvæ kept by Mr. Hawthorne and myself, no less than 75 per cent. were thus destroyed. This larva feeds on the leaves of the sedge, eating out long notches parallel to the veins of the leaf. These notches are the best guides to follow in searching for the larva, as the colouring of the caterpillar renders its discovery amongst the food-plant extremely difficult. The larvæ should be looked for during the end of December or the beginning of January.
The pupa is rather stout, light green, with the edge of the wing-case and the prominences formed by the back and palpi, edged with crimson and white. It is suspended by the tail to any firm object in the neighbourhood of the sedge.
The perfect insect appears in February. It frequents sunny glades in the birch forest, usually at considerable elevations above the sea-level. Mr. Helms informs me that he has seen specimens near Greymouth in October, and hence concludes that there are two broods in the year. The butterfly is very difficult to capture, as it has a most provoking habit of resting on the foliage of the birch-trees, just out of the collector's reach. I am unable to explain the object of the remarkable colouring of the under side of this insect, but it is probably protective, although in what way has yet to be discovered.