The two remaining groups of the Diptera are of very limited extent. ThePupiparainclude 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 thePulicinacomprise the well-known fleas, which are probably identical with the European species. They are placed by many authors in a distinct order termed theAphaniptera.
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.
GroupRhopalocera.
FamilyNymphalidæ.
Argyrophenga antipodum(PlateVIII., fig. 1 type, 1a var.).
Passing over the local but conspicuousDanais plexippus,about which so much doubt exists as to its origin in this country, we come toA. 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 areErebia plutoandErebia butleri, both strictly alpine insects, occurring in the South Island at elevations ranging from 4,000 to 6,000 feet.
FamilyNymphalidæ.
Vanessa gonerilla[15](PlateVIII., 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, thuscausing 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 ofVanessaareV. 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, andV. Itea, a lovely butterfly found in the northern portions of this island, of which I have at present only taken three specimens.
FamilyLycænidæ.
Chrysophanus salustius(PlateVIII., 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 ofChrysophanusoccur 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; andC. 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 LakeWairarapa is one of the best localities I know of for this curious little species.
FamilyLycænidæ.
Lycæna phœbe.
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.
GroupHeterocera.
FamilySphingidæ.
This family is represented in New Zealand by the splendidSphinx convolvuli, an insect I am at present unacquainted with.
FamilyHepialidæ.
Porina signata(PlateIX., fig. 2).
Common throughout the summer, when it may be taken in great numbers round lighted windows during any mild evening. The larva is as yet unknown, but is in all probability subterranean in its habits, and feeds on the roots of plants. A largeHepialuslarva I once discovered under a stone, whilst looking for Coleoptera, was very likely referable to this insect, but as it unfortunately died shortly afterwards it is impossible to speak with any degree of certainty at present. Two closely allied species areP. umbraculata, andP. cervinata. The former is rather smaller thanP. signataand of a more uniform brown, with a white stripe in the centre of each fore-wing, surrounded with darker colouring. The latter is one of the smallest of the family, its size at once distinguishing itfrom any of the rest. In colour it is pale brownish with numerous black and white markings, varieties occasionally occurring much suffused with the darker colour. It is rather local, but may be found abundantly in the Manawatu district.
FamilyHepialidæ.
Hepialus virescens(PlateIX., fig. 1 ♂, 1a ♀, 1c larva, 1b pupa).
This gigantic insect is seen occasionally in the forest during the early summer. The larva (1c) tunnels the stems of living trees, feeding entirely on wood which it bites off with its strong mandibles. The plant most usually selected by the caterpillar isAristotelia racemosa, called by the settlers "New Zealand currant," from its large clusters of rich-looking black berries, which appear in autumn. Other food-plants are numerous, the black maire (Olea apetala) and manuka (Leptospermum) being among those more frequently chosen.
This larva, for the most part, inhabits the main stem of the tree, its gallery always having an outlet to the air, which is covered with a curtain of dull brown silk, spun exactly level with the surrounding bark, and consequently very inconspicuous. These burrows usually run down towards the ground, and are mostly two or three inches from the surface of the trunk. In some instances the larvæ inhabit branches, in which case, if the branch is of small dimensions, the tunnel is made near the centre. These remarks only refer to galleries constructed by young larvæ, as the tunnel made by the insect prior to becoming a pupa is of a very complicated character and merits a somewhat detailed description. It consists of a spacious, irregular, but shallow cavity, just under the bark, having a large opening to the air, which is entirely covered with a thin silken covering, almost exactly the same shape and size asthe numerous scars which occur at intervals on the trunks of nearly all the trees. Three large tunnels open into this shallow cavity: one in the centre, which runs right into the middle of the stem, and one on each side, which run right and left just under the bark. These are usually very short, but sometimes extend half-way round the tree, and occasionally even join one another on the opposite side. The central tunnel has a slightly upward direction for a short distance inwards, which effectually prevents it from becoming flooded with water; afterwards it pursues an almost horizontal course until it reaches the centre of the tree when it appears to suddenly terminate. This, however, is not the case, for, if the gallery floor is carefully examined a short distance before its apparent termination, a round trap-door will be found, compactly constructed of very hard, smooth silk, and corresponding so closely with the surrounding portion of the tunnel that it almost escapes detection. When this lid is lifted a long perpendicular shaft is disclosed which runs down the middle of the tree to a depth of 14 or 16 inches, and is about six lines in diameter. At the bottom of this the elongated pupa (Fig. 1b) sleeps quietly and securely in an upright position, the old larval skin forming a soft support for the terminal segment of the pupa to rest on. The upper end of this vertical shaft is lined with silk, which forms a framework on which the trap-door rests when closed. The lid itself is of a larger size than the orifice which it covers, and this makes it extremely difficult, if not impossible, to force it from the outside, whilst it fits down so closely to the aperture as not to be readily lifted. The object of this most ingenious contrivance is, in all probability, to prevent the ingress of insects, large numbers of spiders, slugs, and various Orthoptera being frequently found in both central and lateral tunnels, but they are quite unable to pass the trap-door. The galleries of different individual larvæ are all wonderfullyalike, the only differences observable being in the length of the perpendicular shaft and the direction of the horizontal burrow, which is sometimes curved. These variations are usually caused by the presence of other tunnels in the tree, which the larva invariably avoids, although how it can ascertain that it is approaching another tunnel before actually reaching it, is hard to understand. As development progresses in the pupa, it becomes darker in colour, especially on the wing-cases, which in some individuals show the future black markings of the moth, as early as two months before emergence. Others remain quite white and soft, the green wings suddenly appearing through their cases a fortnight or three weeks prior to the bursting forth of the imago. Previous to this change the pupa works its way up the vertical tunnel, lifts the trap-door, which yields to the slightest pressure from within, and wriggles along the horizontal burrow until it reaches the air, the last three or four segments only remaining in the tree. The thoracic shield then ruptures, and the moth crawls out and expands its wings in the ordinary way, resting on the trunk of the tree until they are of sufficient strength and hardness for flight.
The perfect insect, although it must be common, is very rarely seen. It is best reared from the pupæ, which can be often successfully cut out of their burrows and kept amongst damp moss until they emerge. It appears to be much persecuted by birds, as we often observe its large green wings lying about on the ground.[16]
The curious "vegetable caterpillar," which is usually referred to this species, probably belongs to one of the larger subterranean larvæ of the family.
FamilyBombycidæ.
Nyctemera annulata(PlateIX., fig. 3 ♂, 3a larva, 3b pupa).
This abundant species is usually mistaken for a butterfly by the uninitiated owing to its diurnal habits and conspicuous colouring. Its larva feeds on various plants, the most usual being a light green kind of ivy with yellow flowers, but its original food no doubt consisted of the "New Zealand groundsel" (Senecio bellidioides), on which it may now be occasionally taken in wild situations. Its general colour is black, with interrupted dorsal and lateral lines, the ventral surface and connecting membrane between the segments being slate-coloured. In younger larvæ there are also several slate-coloured lines extending the whole length of the insect, and thus dividing the black into squares. Round the middle of each segment, at its greatest circumference, a variable number of brilliant blue warts are situated, and out of these dense tufts of long black hair take their rise. There are, however, no warts along the ventral surface. This description applies very well as a rule, but the larva is subject to many slight variations. It remains in this state for nearly three months, or more, according to the season, and is very common, numbers being found on the different plants which constitute its food. The pupa (Fig. 3b) is of a shining black colour, with many longitudinal rows of small yellow blotches on the abdominal segments; there is also a stripe of the same colour at the tip of the wing-case. It is enclosed in a slight cocoon, formed of a mixture of silk and hair, and is attached near the ground to any firm object. The moth emerges in the course of a month or six weeks. It is very common, being found profusely in the neighbourhood of its food-plants, and appears in the greatest numbers during the early morning hours in the middle of summer.
For an account of a Dipterous insect, parasitic in the present species, I refer to page59.
FamilyPsychidæ.
Œceticus omnivorus(PlateX., fig. 1 ♂, 1a ♀, 1b larva, 1c ♂ pupa).
This insect is very rarely seen abroad, but can be easily reared from the larva, which feeds on manuka and other plants throughout the year. When very young, and in fact immediately after leaving the egg, it constructs a wide spindle-shaped case, principally composed of silk, with a few small fragments of leaves, &c., attached to the outside. It has a large aperture in front, through which the head and anterior portion of the larva are projected, and a much smaller one at the posterior extremity, which allows the pellets of excrement to fall out of the case as they are evacuated. The body of the enclosed caterpillar is of a light straw colour, the head and three first segments being dark brown, with numerous white markings. The abdominal segments are considerably thickened near the middle of the insect, rudimentary prolegs being present on the third, fourth, fifth, and sixth segments of the abdomen. The anal prolegs are very strong, and are furnished with numerous sharp hooklets, which retain the larva very firmly in its case. As it grows it increases the length of its domicile from the anterior, causing it gradually to assume a more tubular form, tapering towards the posterior aperture, which is enlarged from time to time. The outside is covered with numerous fragmentary leaves and twigs of various sizes, placed longitudinally on the case, and frequently near the anterior aperture, the materials, owing to their recent selection, are fresh and green. The interior is lined with soft, smooth silk of a light brown colour, the thickness of the whole fabric being about the sameas that of an ordinary kid glove, and so strong that it is impossible to tear it, or indeed to cut it, except with sharp instruments. The size of the case when the caterpillar is mature varies considerably, ranging from 25 to 30 lines or more in length, and about three in diameter, the widest portion being a little behind the anterior aperture (see Fig. 1b).
During the day the larva closes the entrance and spins a loop of very strong silk over a twig, the ends being joined to the upper edges of the case on each side; in this way it hangs suspended, the caterpillar lying snugly within. I have often known a larva to remain thus for over three weeks without moving, and afterwards resume feeding as before; this probably occurs while the inmate is engaged in changing its skin. At night the larvæ may be seen busily engaged: they project the head and first four segments of the body beyond the case, and walk about with considerable rapidity, often lowering themselves by means of silken threads; the only locomotive organs are, of course, their strong thoracic legs, which appear to easily fulfil their double function of moving both larva and case. If disturbed, these insects at once retreat into their cases closing the anterior aperture with a silken cord which is kept in readiness for the purpose, and pulled from the inside by the retreating larva. This operation is most rapidly performed, as the upper edges of the case are flexible, and thus fold closely together, completely obstructing the entrance. When full fed, this caterpillar fastens its case to a branch with a loop of strong silk, which is drawn very tight, preventing the case from swinging when the plant is moved by the wind, and also rendering the insect's habitation more inconspicuous, by causing it to resemble a broken twig. The anterior aperture is completely closed, the loose edges being drawn together and fastened like a bag. The posterior end of the case istwisted up for some little distance above the extremity, thus completely closing the opening there situated. It is lined inside with a layer of very soft silk, spun loosely over the sides, and partly filling up each end. In the centre of this the pupa lies with its head towards the lower portion of the case, the old larval skin being thrust backwards amongst the loose silk above the chrysalis. In this stage of existence the extraordinary sexual disparities, which are so characteristic of the family, manifest themselves, the male and female pupæ being very widely different in all respects. The former is figured at 1c, the female pupa differing from it in the following particulars. It is much larger and more cylindrical in shape, the abdomen occupying nearly the whole of the body, and consisting of nine visible segments, the terminal one being obtusely conical. The head and thorax are very rudimentary, more resembling those of the larva than the male, all the appendages being, however, reduced to hardly visible warts. In colour it is pitchy black and shining, and its length is about ten lines. This insect remains in the pupa state during the winter months, viz., from May till September. When about to emerge, the male chrysalis works its way down to the lower end of the case, forces open the old aperture there, and projects the head, thorax, and upper portion of the abdomen, the pupa being secured from falling by the spines on its posterior segments, which retain a firm hold in the silk. Its anterior portion then ruptures, and the moth makes its escape, clinging to the outside of its old habitation, and drying its wings. It is probable that the female insect does not leave her case, communication with the male being no doubt effected through one of the orifices, and the eggs afterwards deposited inside. On one occasion I found a case full of eggs, containing the shrivelled body of the female and her old pupa shell, which would seem to confirm the above opinion. The perfect insects are drawn atFigs. 1 and 1a. The male (1) is extremely active, dashing about the breeding cage with great rapidity when first emerged, and rapidly beating his wings to tatters; but the female (1a) closely resembles a large maggot, all the appendages being completely rudimentary, except the two-jointed ovipositor at the end of her body; she is incapable of any motion, except a slight twirling of the abdomen, which takes place while the eggs are being laid.[17]
FamilyNoctuidæ.
Leucania nullifera(PlateXIII., fig. 3, 3a larva).
This large, though dull-looking insect, is occasionally taken at light during the summer and autumn months.
The larva feeds on the spear-grass (Aciphylla squarrosa), an abundant plant on the coast hills near Wellington. It devours the soft central-growing point, and its presence in a tussock can be at once seen by a quantity of pale-brown "frass," visible at the bases of the leaves. The formidable spear-like points with which this plant is armed must afford the caterpillar considerable protection from enemies. As a rule a single specimen only is found in each clump of the grass, so that the female probably deposits her eggs singly. This larva is full-grown about August, and may be found feeding in the plants during the autumn and winter.
The pupa state is spent, in an earthen chamber, amongst the roots of the spear-grass, and the moth emerges during the summer.
This species occurs at considerable elevations. I have seen it as high as 4,000 feet in the Nelson province, where its food-plant may also be found.
FamilyNoctuidæ.
Leucania atristriga(PlateX., fig. 2).
Abundant among various blossoms during the latter end of summer, being one of the last of the Noctuæ to disappear in the autumn.
The larva probably feeds on grasses, but I have not yet met with it.
The illustration (Fig. 2) is taken from the male insect, the female differing only in having her abdomen rounded at the tip, a sexual distinction which holds good throughout the family.
FamilyNoctuidæ.
Erana graminosa(PlateX., fig. 5, 5a larva).
This beautiful insect occurs commonly on the white rata blossoms (Metrosideros scandens) round Wellington during March and April, at which time it may be readily taken just after dark with a lantern and killing-bottle. The larva (Fig. 5a) feeds on the mahoe (Melicytus ramiflorus) in the spring and autumn. It remains concealed in crevices in the bark during the day, not infrequently selecting the deserted burrows of wood-boring beetles as a secure retreat from its enemies. When full grown it is olive-green, the colour being lighter on the ventral surface and between the segments. A row of ill-defined, feathery, black markings extends down the back and sides and there are also two tolerably conspicuous ochreish spots on every segment except the last. The head, legs, and prolegs are reddish-yellow, and the whole insect is more or less spotted with black. Younger larvæ differ in being of a light yellowish-green, with very pale yellow dorsal and lateral lines. A row of black warts, emitting a few bristles, extend round each of the segments, while the head is pale ochreous with a few black dots.
When full-grown this larva descends to the ground, andforms a slight cocoon in the earth round the roots of the tree, where it is transformed into a very stout, ruddy-brown-coloured pupa, somewhat paler on the wing-cases. The moth emerges in two or three months' time. Its colouring renders it so inconspicuous amongst moss that I have frequently lifted a handful of the latter out of the breeding cage, and only discovered that the insects had emerged by their falling from the moss on to the table. A very noticeable peculiarity in this species is the presence of a fringe of long hairs in a fold on the anterior margin of the fore-wing. This organ emits a fragrant perfume, and is confined to the male sex (Fig. 5). Only one or two other instances of this kind are at present known among the New Zealand moths.
FamilyNoctuidæ.
Mamestra mutans(PlateX., fig. 7, 7a larva, 7b pupa).
This extremely abundant species occurs almost without intermission during the whole of the year. The sluggish larva (7a) feeds on plantain, and is best obtained by overturning logs and stones, when it may be discovered among the grass and other plants growing round their edge. Its head is pale green, with two broad black stripes, and is clothed with numerous short bristles; the four succeeding segments are of a ruddy-brown colour, considerably wrinkled, the remainder being light green, suffused with a dull, pinkish hue towards the dorsal surface. The markings consist of a triangular black spot on each side of the second to eighth abdominal segments, and a cloudy lateral line of the same colour; the legs and prolegs being pale green, and the whole insect more or less marbled with black. This description and the figure on PlateX. exhibit the usual peculiarities of the larva, but in some individuals the markings there indicated are quite obsolete, and theinsect is of an almost uniform pale-green colour. When mature, this caterpillar sometimes constructs a slight cocoon amongst moss, on fallen trees, but more often buries itself in the usual manner, the moth appearing in a few weeks' time. Nearly all pupæ collected at random in New Zealand will be found to give rise to either this species or the one which immediately follows (Mamestra composita). The perfect insect is most abundant in the spring and early summer, but may be found fluttering round lamps on any mild night throughout the year. The sexes differ considerably: the female is greyish white, with faint brown markings, while the male is dull reddish-brown, with the markings considerably darker (Fig. 7). His antennæ are also slightly pectinated, those of the female being quite simple.
FamilyNoctuidæ.
Mamestra composita(PlateX., fig. 3, 3a larva).
Very common during the spring and autumn in all open situations.
Its pretty larva (Fig. 3a) feeds on various grasses, and threatens in time to do considerable damage to pastures. The head and dorsal surface of the first segment are dark shining green, with one or two obscure white markings; the rest of the body is ornamented with a number of parallel brown, white, and orange lines, which render the larva very inconspicuous when amongst the grass. Sometimes it occurs in great numbers, nearly every blade of grass having its caterpillar; in fact this was almost the case in the Wairarapa valley in the summer of 1886, when the larvæ must have produced a marked effect on the paddocks. When full-grown this caterpillar changes into a light chestnut-brown pupa, which lies on the surface of the ground amongst the vegetable refuse. The perfect insect appears in about a month's time, and if the evening be mildmay be seen flying with great rapidity at dusk; it may also be readily captured at light. The figure (3) represents the male insect, the female differing only in her simple antennæ.
FamilyNoctuidæ.
Mamestra ustistriga(PlateX., fig. 6 ♂).
This handsome insect is rather uncertain in its appearance, but is occasionally taken quite unexpectedly at rest on tree-trunks or palings in the daytime. Specimens may also be captured while feeding on the white rata blossoms early in March, where they occasionally occur among the hosts of other Noctuæ. The larva, which feeds on the honeysuckle, is of a pale brown colour, with two obscure darker lines on each side, the under-surface being light slate-colour. The pupa state is spent in the ground, and many fine specimens may be reared from chrysalids picked up while gardening, &c. The sexes of this insect differ considerably in colour: the male is of a pinkish grey with black markings, while the female is of a uniform pale grey, and considerably smaller.
FamilyNoctuidæ.
Heliothis armigera(PlateX., fig. 4, 4a larva).
This conspicuous insect occurs in great abundance during certain seasons, but is very irregular in its appearance, it frequently happening that only two or three specimens are noticed in a whole year. It is generally seen flying in the daytime, when it delights to suck honey from the flowers of the Scotch thistle, a plant which much overruns the forest lands when first cleared. The larva (Fig. 4a) is a very handsome caterpillar, of a dark brownish black colour, ornamented with yellow subdorsal and lateral lines and numerous streaks and dots of the same hue. The ventral surface is a rich yellowish brown, and the subventral linewhite, the spiracles being white with black rings; a reddish blotch also adorns each of the three thoracic segments. It feeds voraciously on geraniums, tomatoes, peas, and many other garden plants, where it often commits the most serious ravages. About the end of April it is full-grown, when it descends to the ground and buries itself two or three inches below the surface. In this situation it is shortly transformed into a pupa, remaining in that state until the following summer, when the moth appears. The sexes of this insect differ considerably, the male having the fore-wings of a ruddy-brown colour, sometimes inclining to orange, while in the female they are pale ochreish; both sexes are, however, subject to considerable variation, and the figure (4) is taken from a rather dark male specimen.
FamilyNoctuidæ.
Plusia eriosoma(PlateX., fig. 8, 8a larva).
An abundant species round Nelson, where almost any number may be taken hovering over flowers on a still summer's evening. In Wellington it occurs occasionally. The larva (Fig. 8a) is a pseudo-geometer, having twelve legs, and thus showing a strong affinity with the next family. In colour it is pale green, darker on the dorsal surface than elsewhere. A white line runs down each side, and the whole insect is covered with black dots and bristles. The colouring of different individuals varies in intensity, and a fainter white line, above the usual one, exists in some specimens. It feeds on beans, geraniums, and many other imported plants, and is doing much good in the Nelson gardens by the havoc which it is committing among the Scotch thistles—weeds equally injurious to the agriculturalist and the gardener, not only crowding out useful plants, but rapidly exhausting the soil in which they grow. Formerly this insect must have fed exclusively on the New Zealandnightshade (Solanum aviculare), on which plant it may still be occasionally found in the forest, where no imported species are available, but, like many other caterpillars in this country, it is forsaking the native vegetation for the European. When full-grown, this larva spins a slight cocoon of white silk, which is generally placed between two leaves. The pupa is of a shiny black colour, the membrane between the segments being reddish-brown. The moth emerges in about three weeks' time. The figure (8) is taken from a female insect, the male being readily distinguishable by two large tufts of hair situated at the end of his body and often very conspicuous. In some cases the wings of the female are considerably lighter than in the illustration, but otherwise the species does not seem to vary. It is the New Zealand representative of the English "Silver Y Moth" (P. gamma), no doubt familiar to many of my readers.
FamilyGeometridæ.
Declana floccosa(PlateXI., fig. 1, 1a larva).
I have started the Geometridæ withDeclanabecause it exhibits a great many more points in common with the Noctuidæ than does the genusAcidalia, which latter is placed at the head of the Geometridæ by some modern Lepidopterists, chiefly, I believe, on account of neuration, a character which if taken alone cannot but produce the most unnatural divisions. The present insect is one of the commonest of the genus, and may often be observed throughout the whole summer resting on the sheltered sides of trees and fences, occasional stragglers being met with as late as the end of May. Its larva is a pseudo-geometer possessing twelve legs (Fig. 1a), and thus almost exactly resembling the caterpillars of the genusCatocala, belonging to the Noctuidæ; the curious filaments on each side of the insect making this likeness still more complete. It feedson the "New Zealand currant" (A. racemosa), from which, individuals can be occasionally beaten during the spring and early summer. They are almost impossible to find by searching in the ordinary way, from a habit they possess of clinging firmly to the twigs, which they exactly imitate in colour. When full-grown this caterpillar constructs a small cocoon just below the ground, where it is transformed into a robust-looking pupa, from which the moth emerges in a month or six weeks' time. The sexes of this species may be readily distinguished, the male (Fig. 1) having the antennæ slightly pectinated, while those of the female are quite simple, and her body much more robust. The moth drawn at Fig. 1b has been reared from larvæ exactly resembling those of the present insect, of which it is consequently now known to be only an extreme variety. It was formerly ranked as a distinct species under the name ofDeclana junctilinea.
FamilyGeometridæ.
Chalastra pelurgata(PlateXI., fig. 2 ♂, 2a ♀, 2b larva).
This delicate species may be taken flying about the forest at night, from October till March, but is most abundant on the white rata blossoms during the latter end of summer.
Its caterpillar feeds sparingly on a delicate fern (Todea hymenophyllioides) which grows in dark glades in the forest, where the sun seldom or never shines. In colour it is generally dull brown, with a row of green or pale brown lunate spots on each side; on the ventral surface the colour is darker, except on the thorax, where it is green, the legs being also green. There are in addition numerous fine, wavy lines down the back and sides of the larva, and the dorsal surface of the thoracic segments and ventral prolegs are bright reddish brown (Fig. 2b). These larvæ are, however, very variable; in many the "lunate" stripes are much longer, having a diagonal direction, andthus extending up the sides of the insect towards its dorsal surface, while others have the ventral surface dark green, and additional markings of more or less importance.
When full-grown it spins a loose cocoon of earth and dead leaves, from which the perfect insect emerges in a month or six weeks' time. The sexes are widely different, both being figured on the Plate (Fig. 2 ♂, 2a ♀). I have noticed that at least four females occur to every male, which is a very unusual arrangement, the males being generally much the commoner among the Lepidoptera.
FamilyGeometridæ.
Ploseria hemipteraria(PlateXI., fig. 3, 3a larva).
A curious moth, occurring in some numbers at various blossoms during the summer evenings, but rather uncertain in its appearance. The larva (Fig. 3a) feeds at night on veronica, where it may be often found with a lantern, devouring the flowers and leaves. In colour it is light green with two yellow lines on each side, the dorsal surface being considerably darker, and almost blue. Specimens are not infrequently met with of a uniform dark brown, and the two conspicuous lateral lines are then reduced to a single obscure ochreous band. These caterpillars are very inconspicuous during the daytime, as they remain quite motionless for hours together, sticking straight out from the stems of their food-plant, which they closely resemble. The pupa is unusually robust, and possesses a sharp spine at its extremity. In colour it is pale olive brown, with a pinkish line on each side of the abdomen, the wing-cases being more or less suffused with pink. It is not enclosed in any cocoon, but may be found amongst the dead leaves round the stems of the veronica. The perfect insect appears in about three weeks' time. It is liable to be passed over for a faded leaf, the general outline and colouring of the wings rendering theinsect very inconspicuous, especially amongst foliage. The specimens I have reared all closely resemble Fig. 3, so that this insect does not appear at all prone to vary.
FamilyGeometridæ.
Ploseria alectoraria(PlateXI., fig. 4; PlateXIII., fig. 7 larva).
One of our most variable moths, occurring occasionally amongst foliage during the summer, but most abundant on the white rata blossoms in February and March.
The larva feeds onPittosporum eugenioides, where it may be sometimes found in October and November. It has a most wonderful resemblance to the buds of the plant, and can only be dislodged by vigorous beating. It is easily reared in captivity—in fact the female moths may often be induced to lay their eggs and the insect observed through all its stages.
The eggs are very flat, oval, and light green in colour, becoming brown at one end about five days before hatching.
The young larva is pale green with a dull yellowish head. It has no markings until after the first moult when a reddish dorsal line appears. As age advances the larva becomes darker in colour and is ornamented with a series of diagonal yellow stripes. The spiracles and antennæ are pink and very conspicuous. The legs and prolegs are very small, and the latter are bright red in colour; a fleshy process which projects from the last segment of the larva is similarly coloured. The whole insect is also speckled with yellow. When full-grown this caterpillar is very robust and measures about ten lines in length. The pupa is enclosed in a light cocoon formed of three or four leaves fastened together with silk. It is greenish brown in colour.
The perfect insect first appears in December. It may be observed during the whole of the autumn and occasionally in the winter. As the larvæ grow very slowly I aminclined to think that the females hibernate and lay their eggs early in the spring (Fig. 4).
FamilyGeometridæ.
Sestra humeraria(PlateXI., fig. 5, 5a larva).
This abundant species occurs in large numbers round Wellington, amongst brushwood, whence it may be often dislodged during the daytime, but is most readily procurable in the evening. The larva (Fig. 5a), feeds onPteris incisa, a pale green fern, growing in many open spots in the forest to a height of three or four feet. Its general colour is dull brownish yellow, slightly darker on the back, and ornamented with a number of wavy yellow lines on each side. The ventral surface and legs are green and the head is dark brown; the whole insect being covered with numerous black dots and bristles. When disturbed these larvæ immediately drop to the ground, and coiling themselves up like small snakes, become very inconspicuous.
The pupa is buried in the earth about two inches below the surface, the insect remaining in this state during the winter months. The moths generally emerge about October. So far as my experience goes they are not subject to any notable variations. The specimen drawn at Fig. 6 is regarded as a variety of this species by Mr. Meyrick, but I myself believe it to be quite distinct, as among over a dozenhumerarialarvæ reared in captivity, none of the imagines had the slightest resemblance to Fig. 6, although the caterpillars were all taken within a few yards of the place where such moths occurred.
FamilyGeometridæ.
Selidosema dejectaria(PlateXI., fig. 8 ♂, 8a ♀, 8b larva).
An abundant and conspicuous species, occurring throughout the summer, often noticed at rest on fences and treesduring the day and always taken in great numbers on various blossoms in the evening.
The caterpillar is extremely variable, the colouring of different individuals being apparently much influenced by their surroundings; those specimens, for instance, taken from the pale green foliage of the mahoe (M. ramiflorus) resemble in colour the twigs of that plant, while others captured feeding on the white rata (Metrosideros scandens) are dark reddish brown. Fig. 8b is drawn from a larva found on the fuchsia, which, when in its favourite position, viz., sticking straight out from the side of a branch, is so much like one of the sprouting twigs that it absolutely defies detection. When full-grown this insect buries itself about two inches in the earth, where it shortly becomes a dark chestnut-brown pupa, lighter between the segments. The time required for the development of the perfect insect depends upon the season, larvæ which undergo their transformations in the spring developing much more rapidly than those that feed up in the autumn.[18]
This insect is extremely variable, having been formerly divided into several distinct species; the two most usual forms are those shown at Figs. 8 and 8a, but every intermediate variety exists. The sexes are distinguished by the usual differences in the antennæ. My experience leads me to believe that the light varieties occur more frequently in the female than in the male sex, and also that the dark larvæ give rise to dark moths, andvice versâ, although a great many more specimens will have to be reared before these can be regarded as established facts.