Part 12

Cylindria sigma (Plate VII., fig. 14).

A curious species, occurring occasionally in damp situations in the forest where it may be noticed leisurely walking over the leaves of various shrubs. It is very sluggish and may often be captured between the fingers without the aid of a net. Its life-history is at present unknown, but the larva probably feeds on fungi. The pretty little insect depicted at Fig. 11 may be found in similar situations but is not so common.

Family MUSCIDÆ.

Phora omnivora, n.s. (Plate VII., fig. 15, 15a pupa).

This minute species may be found in large numbers nearly all the year round. Its larva is parasitic on a great variety of insects and is also not infrequently met with among decaying vegetable matter. Its habits are, therefore, very varied. When parasitic in the Lepidoptera it usually selects the noctuæ, destroying a great number of many of the commoner species. The infected caterpillars usually turn into chrysalides some time before the little maggots emerge, but this is not invariably the case, the parasite often destroying the larva at a comparatively early stage. The pupæ are buried in the earth, near the remains of their host, and are light brown in colour, with the segments much more distinct than is usual (Fig. 15a). From these the perfect flies proceed in about a month's time. The occurrence of this insect as a parasite in Coleoptera is not common, but I know of one instance {63}in which a number of these little flies were produced from a pupa of Uloma tenebrionides (Plate II., Figs. 2, 2a, 2b), which I was rearing at the time (page 29). In this case it is difficult to understand how the female contrives to deposit her eggs in a horny beetle larva which lies safely hidden in its narrow tunnel in the middle of a large log of wood. Among bees this is a most destructive insect, its larva being parasitic in their grubs, and thus greatly reducing the population of the hive, which is finally ruined by the wholesale destruction of its honey when the flies emerge. Driving the bees into a fresh box would, no doubt, be frequently beneficial in these cases, but it is to be feared that bee-keepers will have much difficulty in contending with this insect. Its sexes are readily distinguished by their size, the female being considerably the larger.

Family MUSCIDÆ.

Coelopa littoralis (Plate VII., fig. 13).

Extremely abundant on the sea-beach. Its larva feeds on decaying seaweed, burying itself in the sand before changing. The perfect insects often congregate in such vast numbers on some of the rocks that it is necessary to run past them in order to avoid being positively suffocated by the countless multitudes which fly up into one's face. This insect must be regarded as the New Zealand representative of the well-known dungfly of England (S. stercoraria), which many of my readers will recollect has a similar habit of assembling in great numbers.

Family OESTRIDÆ.

Oestrus perplexus, n.s. (Plate VII., fig. 12).

This species is mentioned here as it is the only New Zealand exponent of a very important and well-known {64}family of Dipterous insects. I am at present quite ignorant as to its life-history which would, no doubt, be very interesting. The only two specimens I possess were taken at Nelson, some four years back, so that it appears to be very rare.

The two remaining groups of the Diptera are of very limited extent. The Pupipara include a few anomalous species, in which the young are not deposited until they become pupæ, thus undergoing all their transformations within the body of the parent, while the Pulicina comprise the well-known fleas, which are probably identical with the European species. They are placed by many authors in a distinct order termed the Aphaniptera.

{65}CHAPTER VI

The Lepidoptera.

This Order includes the well-known Butterflies and Moths which are the first insects to arrest attention on account of their beautiful colouring and conspicuous appearance. Some of the families are fairly numerous in New Zealand, but the diurnal section is decidedly poorly represented, our total number of butterflies being limited to fifteen, of which one (Diadema nerina) has unquestionably been introduced from Australia, although it will doubtless shortly effect a permanent settlement in the Nelson district, where several specimens have recently been observed. Among the others only four species can be called at all common, the remaining twelve only occurring in certain favoured localities. Of the moths there are a large number, chiefly belonging to the Geometridæ and Micro-Lepidoptera, many of which are very interesting. Of the life-histories of the latter, however, I regret to say there is little known at present, the attention of naturalists having been hitherto chiefly occupied with the larger and more conspicuous species.

Group RHOPALOCERA.

Family NYMPHALIDÆ.

Argyrophenga antipodum (Plate VIII., fig. 1 type, 1a var.).

Passing over the local but conspicuous Danais plexippus, {66}about which so much doubt exists as to its origin in this country, we come to A. antipodum, one of the most curious and interesting butterflies found in New Zealand. It occurs in great abundance amongst the tussock grass on the plains in the South Island, but becomes an alpine species further north. I have taken a very peculiar form (Fig. 1a) on the "Mineral Belt" near Nelson, but can find no record of its appearance in the North Island at present. Its larva is as yet unknown, but in all probability it feeds on tussock grass, a fractured pupa having been found attached to that plant by Mr. G. F. Mathew in January, 1884. Two other closely allied species are Erebia pluto and Erebia butleri, both strictly alpine insects, occurring in the South Island at elevations ranging from 4,000 to 6,000 feet.

Family NYMPHALIDÆ.

Vanessa gonerilla (Plate VIII., fig. 2, 2a underside, 2b 2c larvæ, 2d 2e pupæ).

One of our most beautiful butterflies, found abundantly throughout the country from August till May. The larva feeds on the New Zealand nettle, where it may be taken in great plenty by careful searching. The caterpillar joins several of the leaves together and forms a sort of tent, in which it lives secure from all enemies. While young, these insects are of a uniform dull brown colour, with two faint lines on each side, but as age advances they become very variable. The two extreme forms of variation are depicted at Figs. 2b and 2c, the dark-coloured variety being by far the commoner. When full-grown, this larva suspends itself by the tail to a small patch of silk, which it has previously spun on the under side of a leaf. In this position it remains for about twenty hours, when it begins to twist and distend the lower portions of its body, thus {67}causing the skin to eventually break on the back of the thoracic segments, when the soft green pupa may be seen through the rent. The insect now works the skin upwards by violent wriggling motions until it is gathered in a crumpled mass round its tail, the old rent extending on one side almost up to the silken pad to which it is suspended. Through this rent the tail of the pupa is brought and firmly anchored in the silk by a few vigorous strokes, the insect hanging meanwhile to the skin which has not been quite cast off on the reverse side to the rent. When thus firmly attached to the silken pad, the pupa shakes itself entirely free, whirling itself round and round until the old skin is dislodged from the silk and falls to the ground. The two usual varieties of pupæ are shown at Figs. 2d and 2e, many of them being more or less ornamented with metallic gold or silver spots. The butterfly emerges in a fortnight or three weeks, and is common from February till April in most situations, but the greatest numbers are to be found in the spring months. These hybernated specimens appear as early as August, and some of them survive till the end of December or beginning of January, when the earliest of the new ones are just emerging. In fact it is not infrequent at this time to take both hybernated and recent specimens together. This species is a great traveller, and may be often seen flying over the tops of the trees at a great rate. It shows a singular indifference to shadow, and is constantly flying out of the sunlight into shady places in the forest, probably in search of the food-plant of the larvæ. The two other species of Vanessa are V. cardui, a periodical insect only distinguished from the "Painted Lady Butterfly" of England by the blue centres in three of the black spots on its hind-wings, and V. Itea, a lovely butterfly found in the northern portions of this island, of which I have at present only taken three specimens.

{68}Family LYCÆNIDÆ.

Chrysophanus salustius (Plate VIII., fig. 3 , 3a , 3b larva).

This is the commonest of our Butterflies, and is found in great abundance throughout both islands from November till April. It is double brooded, and is consequently most abundant in the early summer and in the autumn, few of these merry little insects being seen at midsummer. The most forward individuals of the second brood usually emerge about the middle of March, but the butterflies are very irregular in their appearance at this season. The young larva (Fig. 3b) is much thickened anteriorly, the head being concealed from above by the large thoracic segments. Its colour is pale green, with a pair of long, erect bristles on each segment, a large number of shorter ones being situated on the ventral surface, and behind the head. After the second moult, a brilliant crimson dorsal line is noticeable, but beyond this I have no record, as my larvæ unfortunately died just after completing their third moult. Up to this time they had fed but sparingly on the dock, eating minute holes in the leaves and clinging to them with great firmness. It is much to be regretted that their subsequent history could not be followed, especially as I only succeeded in obtaining the eggs on this one occasion, although I frequently kept females in captivity with this object. Three other species of Chrysophanus occur in New Zealand, viz., C. feredayi, common round Nelson, and chiefly distinguished by the olive-green under-surface of its hind-wings; C. enysii, which is occasionally met with amongst forest, and may be at once known by its broad black markings and pale yellow colour; and C. boldenarum, a little insect uniting the "Coppers" with the "Blue Butterflies," and found in great abundance in certain river beds and shingly places. The western side of Lake {69}Wairarapa is one of the best localities I know of for this curious little species.

Family LYCÆNIDÆ.

Lycæna phoebe.

This is the common blue butterfly of New Zealand, which may be observed in great numbers along the roadside on a hot summer's day. Its larva must be very abundant, but has hitherto escaped attention, owing, probably, to its small size. The perfect insect is on the wing from October till May.