Genus 1.--HEPIALUS, F.
"Antennæ 1/8 to ¼, in male lamellate or simple. Palpi short, drooping,
hairy. Posterior tibiæ usually densely rough-haired, in male sometimes
with long projecting tuft above. Fore-wings with vein 7 from angle, 8
remote, 9 and 10 stalked. Hind-wings as fore-wings, 8 seldom connate or
stalked with 7." (Plate I., figs. 22 and 23, neuration of _Hepialus
virescens_, 24 head of ditto.)
"A genus of universal distribution, but not very numerous in species. Ovum
spheroidal, smooth. Larva elongate, active. Pupa with segmental whorls of
spines, enabling it to move actively before emergence."--(Meyrick.)
Represented by one species only--the largest moth we have in New Zealand.
{129}HEPIALUS VIRESCENS, Dbld.
(_Hepialus virescens_, Dbld., Dieff. New Zeal., ii. 284; White, Taylor
New Zeal., pl. i. 6. _Hepialus rubroviridans_, White, l.c., pl. i. 1.
_Charagia virescens_, Walk., Bomb., 1569; Scott, Trans. Ent. Soc. N. S.
Wales, ii. 28. _C. fischeri_, Feld., pl. lxxx. 1. _C. hectori_, Butl.,
Proc. Zool. Soc. Lond., 1877, 380. _Hepialus virescens_, Meyr., Trans. N.
Z. Inst., xxii., 211.)
(Plate XIII., fig. 16 [M], 17 [F]; Plate III., fig. 23 larva, 30 pupa.)
This large and conspicuous insect appears to be generally distributed
throughout the North Island.
The expansion of the wings of the male is 4 inches, of the female
sometimes fully 5½ inches. The fore-wings of the male are _bright green,
with a series of paler ring-shaped markings between the veins; an
irregular row of white spots crosses the wing near the middle_, and a
small white spot is situated on the costa at the base. The hind-wings are
very pale yellowish-brown near the body, becoming pure white in the
middle, and pale green on the termen. The head and thorax are green, the
abdomen is white, tinged with green at the apex. The female has all the
wings of a relatively more attenuated shape; _the fore-wings are green,
mottled with black_; the hind-wings are pale reddish-brown, shaded with
green near the termen; the abdomen is also reddish-brown, becoming green
at the extremity.
The species is rather variable in both sexes. In the male the white spots
on the fore-wings vary considerably in size, and there are occasionally
several additional spots near the body. In the female the black markings of
the fore-wings are sometimes much more extensive than the green ground
colour. This dark form of the female was described by Butler as a distinct
species, under the name of _Charagia hectori_. In both sexes the green
colouring is occasionally entirely absent, a dull orange-brown taking its
place. I formerly attributed this peculiarity to the effects of fading, but
Mr. Norris has shown me a very perfect specimen of this variety, which he
bred from the pupa, he having noticed the orange-brown colouring
immediately after the insect emerged.
The transformations of this insect are very interesting. The female lays an
enormous number of very small, round, yellowish eggs, which she seems to
deposit quite indiscriminately. The young larvæ consequently have to find
their way along the ground to the stems of their food-plant, a large
percentage no doubt perishing before they succeed in doing so, and this
circumstance probably accounts for the great number of eggs produced.
The food-plants of this species are numerous; the following are a few of
them: "wineberry" or "currant" (_Aristotelia racemosa_), apparently the
favourite; "manuka" (_Leptospermum ericoides_); "ki-ki" (_Astelia
solandri_); "black maire" (_Olea apetela_); titoki (_Alectryon excelsum_);
and _Melicope_. The larva tunnels the stems of these trees, feeding
entirely on the wood, which it bites off with its strong mandibles.
For the most part it inhabits the main stem of the tree, its gallery always
having an outlet, which is covered with a curtain of silk and refuse, and
is spun exactly level with the surrounding bark, and very inconspicuous.
These burrows usually run 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 they are small, the tunnels are made near the
centre. Later on in its life, but probably some time before its
transformation into the pupa, the caterpillar of this insect constructs a
far more complicated burrow than the above. It consists of a spacious,
irregular, but shallow cavity, just under the bark, having a very large
opening to the air, which is entirely covered {130}with a thin silken
curtain, almost exactly the same shape and size as the numerous marks
occurring at intervals on the trunks of many of the trees. Three large
tunnels open into this shallow cavity: one in the centre, which runs into
the middle of the stem, and one on each side, which run right and left just
under the bark. These lateral tunnels are usually very short, but sometimes
they 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 in wet weather; 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 be
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 with the surrounding portion of the tunnel so
exactly 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 ½ inch in diameter. The upper end
of this 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 open from the exterior, especially as it always
fits down very closely as long as the insect remains in its burrow. The
object of this contrivance is, no doubt, to prevent the ingress of enemies,
large numbers of spiders, slugs, wood-lice, 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 individual larvæ are all
wonderfully alike, the only differences observable being in the length of
the perpendicular shaft, and in 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 appears to carefully
avoid; at least I have never known an instance where a larva has allowed
its tunnel to communicate with another one, whether inhabited or otherwise.
The caterpillar, when full grown, measures from 2½ to 3 inches in length.
It is tolerably uniform in thickness, and of a dull yellow colour. The
head is large, dark brown, very irregularly striated, and covered with a
few short bristles. The first segment is hard and shining with the back
and sides ruddy-brown. Its spiracle, which is very large, is situated
near the posterior margin, and a little above it there is a dull black
spot, filling a slight concavity about the same size as the spiracle
itself. Each remaining segment has on its dorsal surface two horny
plates, and two similar plates are situated on each side immediately
below the spiracle. The body of the larva is thinly covered with yellow
and black bristles. In many specimens the ventral surface and connecting
membrane between the horny plates is pale purple. Younger specimens
differ in being of an olive-green colour, which is much more pronounced,
when they are small.
The last act performed by the caterpillar, prior to undergoing its
transformation, is the construction of the above-described trap-door at the
top of its burrow. This done the insect retreats to the bottom, its
posterior segment resting on the termination of the vertical gallery. In
the course of a few days the skin is cast off and worked downwards to the
bottom of the burrow, underneath the last segment of the pupa.
This pupa varies from 2 to 2½ inches in length. It is attenuated in form
and pale reddish-yellow in colour. The head and dorsal portion of the
thorax are dark brown and harder than the rest of the body. The edges of
the abdominal segments are furnished dorsally with a row of small
{131}hooklets above and below all the divisions; on the ventral surface
there is only a single row, which is situated in front of each
articulation.
As development progresses in the pupa it becomes darker in colour,
especially on the wing-cases, where, in some female specimens, the future
black markings of the moth are quite discernible as long as two months
before emergence. Other specimens remain pale in colour until within a
fortnight or three weeks of the appearance of the imago, when the green
colouring of the wings suddenly becomes visible through their
semi-transparent envelopes.
When about to emerge the pupa works its way up the vertical tunnel by means
of the above-mentioned hooklets, forces open the trap-door, and wriggles
along the horizontal burrow until it reaches the air, only the last three
or four segments remaining in the tree. Its anterior portions then break
open 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 appears in October and November. Although it must be
common, it is rarely seen; specimens are consequently best obtained in the
pupa state and reared in captivity. The easiest way to find the pupa is to
pass a straw into the horizontal burrow, and move it about until it touches
the trap-door. The collector is at once apprised of this circumstance by a
distinct hollow sound, produced by the straw when it comes in contact with
the lid, which acts like a miniature drum. If no such sound is heard after
moving the straw into every possible position, it may be assumed either
that the insect has left the burrow, or that it is inhabited by a larva
only. When, however, a pupa is actually discovered, a section of the
tree-trunk should be cut out, extending from about two inches above the
horizontal burrow to about one foot below it, and the log, thus obtained,
taken home. Should a number of pupæ be found in one tree the whole trunk
may then be taken, if practicable, and kept in a well-lighted room or a
conservatory, until the enclosed insects emerge. The specimens usually come
out of the pupa at about five or six o'clock in the evening, and if
intended for the cabinet should be killed before dark, as they very soon
injure themselves when flying.
The best time of year to obtain the pupa of this insect is during August
and September, as most of the specimens are then in that condition. Apart
from the indications above described, burrows containing larvæ may often be
known by the fresh pellets of excrement which are present near the opening.
The vacated burrows frequently have the remains of the old pupa shell at
the entrance, and generally look gnarled and weather-worn. These
indications are useful as guides to the collector before exploring the
burrow with a straw in the manner above described.
This insect is much attracted by light, and in consequence sometimes enters
shop-windows and houses. In fact nearly all the _captured_ specimens are so
taken, the moth being very rarely found in its native forests. This
circumstance is no doubt due to its very perfect protective colouring
which, notwithstanding its large size, causes it to be almost invisible,
when resting on the branch of a tree. On one occasion I discovered a
specimen in this situation; being obliged to leave it for a short time, I
experienced the utmost difficulty in finding it again, although I had taken
a special note of its position. This species appears to be much persecuted
by insectivorous birds, as we may frequently see its large green wings
lying on the ground, where they are very conspicuous.
{132}Genus 2.--PORINA.
"Antennæ ¼-2/5, in male bi-pectinated, or more or less shortly
bi-dentate. Palpi moderate, porrected, basal joint rough-haired, second
joint rough-haired or almost smooth, terminal joint smooth, sometimes
subclavate. Posterior tibiæ densely rough-haired. Fore-wings with vein 7
from angle of cell, 8 and 9 out of 10, rising from upper margin much
before angle. Hind-wings as in fore-wings."--(Meyrick.) (Plate I., figs.
28 and 29 neuration of _Porina signata_.)
Of this genus we have eight species in New Zealand.
PORINA DINODES, Meyr.
(_Porina dinodes_, Meyr., Trans. N. Z. Inst. xxii. 206.)
(Plate XIII., fig. 8.)
This handsome species was discovered at Invercargill by Professor Hutton.
The expansion of the wings is 2¾ inches. The fore-wings are dark brown.
There is an irregular white mark with a brown centre at the base, several
white dots and crescentic marks near the middle, an oblique series of
double crescentic marks followed by a considerably fainter series near
the termen. The hind-wings are yellowish-brown; the cilia of all the
wings are white, barred with dark brown. _The antennæ of the male are
strongly bi-pectinated._
Described and figured from a specimen in Mr. Fereday's collection.
PORINA MAIRI, Buller.
(_Porina mairi_, Buller, Trans. N. Z. Inst. v. 279, pl. xvii., Meyr.,
Trans. N. Z. Inst. xxii. 207.)
A single specimen of this fine species was discovered by Sir Walter Buller
on the Ruahine Ranges, in the Wellington district, during the summer of
1867.
The expansion of the wings is about 5 inches. "Wings large, broad,
front-wings produced, ovate-triangular, pale dirty testaceous; six black
spots terminating veins on outer margin, and bounded by a lunated
marginal white band; a submarginal series of arrow-headed black spots,
and beyond these a series of rounded spots, the first four encircled with
white, the rest with pale brown; two broken, black discal lines filled in
with brown; a broad irregular band to below centre of wing, beyond cell,
and formed of three black lines with brown interspaces; a triangular
white spot below cell and a white patch terminating it and traversed by
two black crosses; two diverging black bars surrounded with white in
centre of cell and a third surrounded with dirty testaceous near base; a
large irregular patch of whitish-brown below end of cell, bounded on
internal area by three unequally formed patches which together almost
form the sides of a large triangle; two small spots near base; hind-wings
greyish, becoming browner towards outer margin and crossed by eight
interrupted black bars."--(Buller).
The type specimen of this species was unfortunately lost in the wreck of
the barque 'Assaye' in 1890. I have copied the above from Sir Walter
Buller's original paper, and it may be well to point out that his
description proceeds from the termen to the base, being the _reverse_ order
to that followed by me in all the other descriptions in this work.
The so-called "vegetable caterpillar" (infested with the _Sphæria_ fungus
[_Cordiceps robertsii_]) is, I think, very probably the larva of this
insect. It was formerly supposed to be the larva of _Hepialus virescens_;
but I have pointed out elsewhere[68] that this is certainly erroneous, the
larva of _H. virescens_ living in the stems of trees, and never going
beneath the ground, even to pupate, whilst the "vegetable" larva is
subterranean. The real point to be discovered is the precise species of
_Lepidoptera_ this caterpillar would develop into, if not attacked by the
fungus; but at present no definite information has been obtained on the
subject.
{133}PORINA ENYSII, Butl.
(_Porina enysii_, Butl., Proc. Zool. Soc. Lond., 1877, 381, pi. xlii. 7.
_Porina enysii_, Meyr., Trans. N. Z. Inst. xxii. 207.)
(Plate XIII., fig. 9 [M], fig. 10 [F].)
This species appears to be confined to the North Island, where it is rather
rare.
The expansion of the wings of the male is 2½ inches, of the female 3½
inches. The fore-wings are dark orange-brown, more or less marbled with
yellow and dark brown; there is a very variable number of small dull
white spots margined with black and arranged irregularly on the wing.
_The hind-wings are pinkish-brown, tinged with ochreous on the termen._
This species varies a good deal in the extent of the darker markings, and
number and position of the dull white spots. When alive it is usually very
strongly tinged with pink.
The perfect insect appears in December and January, and frequents forests.
It is especially fond of resting on the stems of tree-ferns in the daytime,
where, however, it is extremely inconspicuous, and can only be discovered
by very careful searching. It is also very partial to light, and specimens
might perhaps be secured more plentifully, if a good attracting lamp were
exhibited in a suitable locality.
PORINA CHARACTERIFERA, Walk.
(_Hepialus characterifer_, Walk., Suppl. 594. _Oxycanus impletus_, ib. 598.
_Porina characterifera_, Meyr., Trans. N. Z. Inst. xxii. 208.)
(Plate XIII., fig. 11 [M].)
This fine species has been taken in the North Island at Auckland, Kaitoke,
and Wellington.
The expansion of the wings is about 3 inches. The fore-wings are rather
dull yellow, finely marbled with black; _there are two conspicuous
irregular black marks a little above the middle of the dorsum. The
hind-wings are very dark purplish-brown with the cilia yellow, barred
with brown._ The head and thorax are dull yellow, speckled with black,
and the abdomen is dark purplish-brown, barred with dull white, with a
yellow tuft at the apex.
The perfect insect appears in October, November, and December. At present I
am only aware of four specimens in collections, viz., two in the British
Museum, taken at Auckland; one in Mr. Meyrick's collection, taken by Mr. H.
B. Kirk on the Rimutaka Ranges, at an elevation of about 1,500 feet; and
one kindly given to me by Mr. W. R. Morris, who took it at Wadestown, near
Wellington.[69] It is evidently a scarce species, but may be looked for in
the forest districts of the North Island.
PORINA CERVINATA, Walk.
(_Elhamma cervinata_, Walk., Suppl. 595. _Porina vexata_, ib. 597.
_Pielus variolaris_, Gn., Ent. Mo. Mag. v. 1. _Porina fuliginea_, Butl.,
Cist. Ent. ii. 488. _Porina cervinata_, Meyr., Trans. N. Z. Inst. xxii.
208.)
(Plate XIII., fig. 12 [M], fig. 18 variety of [F].)
This insect is fairly common, and generally distributed throughout the
country. It is very abundant in the Manawatu district.
The expansion of the wings is about 1½ inches. The fore-wings vary from
brownish-black to dull yellow; there are several small white spots near
the base margined with black, and an obscure cloudy central streak,
sometimes containing one or two minute irregular white marks; near the
termen a broad, pale, wavy line runs from the costa to the dorsum, and
contains several elongate dull white spots, margined with black; another
series of smaller spots is often situated between this line and the
termen; there is a terminal row of small black spots. The {134}hind-wings
vary from pale greyish-brown to dull yellow. The cilia of all the wings
are barred with dark brown.
This species is extremely variable. In many cases a large number of the
spots is wanting. Mr. Meyrick states that the northern specimens are more
yellow-ochreous, and more distinctly spotted than the southern ones. He
adds that "the ochreous forms are easily distinguished from other species
by the numerous spots and the absence of a continuous pale discal streak;
the fuscous forms are sometimes very similar in colouring to _P. despecta_,
but they are distinctly shorter-winged, and the compound discal spots
appear to be a good character."
I have taken several specimens of what appears to be a variety of this
species on the Tableland of Mount Arthur. It is much paler than the typical
form, the markings much less distinct, and the central portions of the
fore-wings very pale yellow (see fig. 18).
The moth appears in October. It is very much attracted by light.
PORINA DESPECTA, Walk.
(_Hepialus despectus_, Walk., Suppl. 594. _Porina despecta_, Meyr., Trans.
N. Z. Inst. xxii. 209.)
(Plate XIII., fig. 13 [F].)
This species has occurred in the South Island, at Christchurch, the Otira
River and Lake Wakatipu.
The expansion of the wings is from 1½ to 1¾ inches. The fore-wings are
dull brown with several irregular dull white markings near the centre of
the wing. The hind-wings are also dull brown. In general appearance it
closely resembles the last-mentioned species (_P. cervinata_), _but may
always be recognised by its longer and narrower wings, smaller body and
antennæ, and absence of distinct markings near the termen_.
The perfect insect appears in January, and is usually taken at light.
PORINA UMBRACULATA, Gn.
(_Pielus umbraculatus_, Gn., Ent. Mo. Mag. v. 1. _Porina umbraculata_,
Meyr., Trans. N. Z. Inst. xxii. 209.)
(Plate XIII., fig. 14 [M].)
This species is probably common, and generally distributed throughout the
country. It has been taken at Palmerston, North Wellington, Nelson,
Christchurch, Invercargill and Stewart Island.
The expansion of the wings of the male is 1¾ inches, of the female 2¼
inches. The fore-wings are dull yellowish-brown; _in the centre there is
a broad longitudinal blackish streak, containing a conspicuous straight
white stripe, occasionally broken into two or three very elongate spots_;
there are often several black dots along the termen. The hind-wings are
dull ochreous, strongly tinged with pink towards the base.
This species varies considerably in the depth of the ground colour, and in
the number of the black dots. A blackish shaded line, parallel to the
termen, is also frequently present. The species may, however, be at once
recognised by the straight, white, central stripe of the fore-wings.
The perfect insect appears from October till January, and is generally
captured at light.
PORINA SIGNATA, Walk.
(_Elhamma signata_, Walk., Bomb. 1563. _Porina novæ-zealandiæ_, ib. 1573.
_Porina signata_, Meyr., Trans. N. Z. Inst. xxii. 210.)
(Plate XIII., fig. 15 [M]; Plate III., fig. 6 larva.)
Apparently an abundant species in the North Island, having been taken
{135}commonly at Napier, Palmerston and Wellington. I suspect it occurs in
the South Island also, but I have no records of its capture there.
The expansion of the wings is from 2 to 2¼ inches. The fore-wings are
dark brownish-ochreous, becoming dull white near the middle and on the
termen; _there is a shaded central, longitudinal, blackish band
containing several white spots, forming an irregular stripe in the middle
of the wing_; there are also many irregular markings with dull white
centres, chiefly situated near the veins, and often arranged in two or
three rows parallel to the termen. All the markings are very variable,
but the insect may be at once known by the irregular central white
stripe. When alive the entire colouring is always strongly tinged with
pink.
I have often found a large subterranean caterpillar, that I believe to be
the larva of this insect; but as I have never succeeded in rearing a
specimen, I cannot assign it to this species with absolute certainty.
The length of this larva when full grown is nearly 3 inches. Its colour
is dirty white, becoming darker on the back. The head is dark brown, very
rough and horny; the three first segments are also horny on the dorsal
surface. The rest of the body is very much softer, and is furnished with
several horny tubercles, each of which emits a long bristle.
This larva is very lively when disturbed. It usually disgorges a large
quantity of black juice from the mouth, biting meantime, in order no doubt
to frighten its enemies. It feeds on the roots of various grasses.
The perfect insect appears in January, February and March, and is often
extremely abundant at light.
{137}APPENDIX.