Genus 1.--ANOSIA.
"Eyes glabrous. Club of antennæ elongate, gradual. Fore-wings with vein
10 separate. Hind-wings with transverse vein present." (Plate I., figs. 7
and 8, neuration of _A. erippus_.)
"A genus of moderate extent, generally distributed within the tropics, with
two or three species ranging beyond them. Imago with termen of fore-wings
sub-concave. Larva with pairs of long tentacles. Both larva and imago are
protected by a strong nauseous scent, or taste, and are uneatable to
birds."--(Meyrick.)
We have two species in New Zealand.
ANOSIA ERIPPUS, Cr.
(_Papilio archippus_, Fabricius, Spec. Ins., p. 55, n. 243 (1781).
_Danais archippus_, Butler, Butterflies of N. Z., Trans. N. Z. Inst. x.
265. _Anosia plexippus_, L.)
(Plate XI., fig. 1, fig. 2 under side; Plate III., fig. 3 larva, fig. 27
pupa.)
This handsome insect has occurred from time to time at various localities
in both the North and the South Islands, but does not appear to be
generally common. Particulars of the early captures of this butterfly are
thus given by Mr. Enys[44]: "First recorded as a New Zealand insect by Mr.
Fereday, in a paper read before the Canterbury Institute, January 2, 1874,
and printed in vol. vi. of 'Transactions.' Mr. Fereday received the
butterfly from F. H. Meinertzhagen, of Hawkes Bay. Dr. Hector also obtained
it in Westland. It has also been caught near Auckland. In vol. xi. of
'Transactions' Mr. F. W. Sturm records that he first saw this insect, or a
closely allied one, at the Reinga, up the Wairoa River, Hawkes Bay,
December, 1840, or January, 1841. In 1848 he captured a number at the
Waiau, a tributary to that river. Again in 1861 he captured three on the
Rangitikei River near Mr. Birch's run. He also records other captures."
From these records it will be seen that the insect was observed as early as
1840, and it thus seems scarcely probable that it was accidentally
introduced by man, as Mr. Butler appears to suppose.[45] Recently _A.
erippus_ has occurred many times in the neighbourhood of Cook's Straits. In
1879 several specimens were bred from larvæ found by Mr. C. W. Lee near
Wangaehu. In 1881 I captured two specimens near Nelson and saw three
others. In 1890 two specimens were taken by Mr. R. I. Kingsley, and in
January of the following year I captured two more, all near Nelson. During
the autumn of 1892 {103}one specimen was taken near Otaki by Mr.
Rutherfurd, and several others were seen. The same year a specimen was also
taken by Sir James Hector at Petone. In 1896, I understand from Mr.
Kingsley, several specimens were again seen in the Nelson district.
The expansion of the wings is from 3¾ to 4¼ inches. Above, all the wings
are rich orange-brown bordered with black, the veins are also black.
There are two rows of small white spots round the margins of all the
wings, and several orange-brown spots near the apex of the fore-wings.
Beneath, the markings are similar, except that the white spots are
larger, and the hind-wings are very pale yellowish-brown. The male has a
black chitinous spot on vein 2 of the hind-wings which is wanting in the
female; the wing-veins in the male are also slightly narrower.
The larva of this insect feeds on most of the different kinds of milkweed
(_Asclepias_), and also upon dogbane (_Apocynum_). A single caterpillar,
fully grown, which was found in a building in the centre of the town of
Wellington, formed the subject from which the figures of the metamorphosis
of this insect were taken, but this specimen did not afford sufficient
material for an exhaustive investigation of the life-history. The following
account, taken from Professor Riley's 'Third Annual Report of the Noxious,
Beneficial, and other Insects of the State of Missouri,' is therefore
inserted:--
"The egg is invariably deposited on the under side of a leaf, and is
conical and delicately reticulate with longitudinal ribs, and fine
transverse striæ. It is yellowish when first deposited, but becomes grey
as the embryo within develops.
"In about five days after laying the egg hatches, and the young larva as
soon as hatched usually turns round and devours its egg-shell--a custom
very prevalent with young caterpillars. At this stage it differs
considerably from the mature larva; it is perfectly cylindrical, about
0·12 inch long, and of much the same thickness throughout. The head is
jet black and polished; the colour of the body is pale greenish-white,
with the anterior and posterior horns showing as mere black conical
joints, and with two transverse-oval black warts, nearer together, on the
first joint. It is covered with minute black bristles, arising from still
more minute warts.
"When the young larva is three or four days old a dusky band appears
across the middle of each joint, and by the fifth or sixth day it spins a
carpet of silk upon the leaf, and prepares for its first moult. After the
first moult the anterior horns are as long as the thoracic legs, the
posterior ones being somewhat shorter; the characteristic black stripes
show quite distinctly, but the white and yellow stripes more faintly.
After this it undergoes but slight change in appearance, except that the
colours become brighter, and that at each successive moult the horns
become relatively longer. There are but three moults, and the intervals
between them are short, as the larvæ frequently acquire their full growth
within three weeks from hatching.
"As soon as the larva is full grown it spins a little tuft of silk to the
under side of whatever object it may be resting upon, and after entangling
the hooks of its hind legs in the silk it lets go the hold of its other
legs and hangs down, with the head and anterior joints of the body curved.
In this position it hangs for about twenty-four hours, during which the
fluids of the body naturally gravitate towards the upturned joints, until
the latter become so swollen that at last, by a little effort on the part
of the larva, the skin bursts along the back behind the head. Through the
rent thus made the anterior portion of the pupa is protruded, and by
constant stretching and contracting the larval skin is slipped and crowded
backwards until there is but a small shrivelled mass gathered around the
tail. Now comes the critical period--the culminating point.
"The soft and supple chrysalis, yet showing the elongate larval form with
distinct traces of its prolegs, hangs heavily from the shrunken skin. From
this skin {104}it is to be extricated and firmly attached to the silk
outside. It has neither legs nor arms, and we should suppose that it would
inevitably fall while endeavouring to accomplish this object. But the task
is performed with the utmost surety, though appearing so perilous to us.
The supple and contractile joints of the abdomen are made to subserve the
purpose of legs, and by suddenly grasping the shrunken larval skin between
the folds of two of these joints as with a pair of pincers, the chrysalis
disengages the tip of its body and hangs for a moment suspended. Then with
a few earnest, vigorous, jerking movements it succeeds in sticking the
horny point of its tail into the silk, and firmly fastening it by means of
a rasp of minute claws with which that point is furnished. Sometimes severe
effort is needed before the point is properly fastened, and the chrysalis
frequently has to climb by stretching the two joints above those by which
it is suspended, and clinging hold of the shrivelled skin further up. The
moment the point is fastened the chrysalis commences, by a series of
violent jerkings and whirlings, to dislodge the larval skin, after which it
rests from its efforts and gradually contracts and hardens. The really
active work lasts but a few minutes, and the insect rarely fails to go
through with it successfully. The chrysalis is a beautiful object, and as
it hangs pendant from some old fence-board or from the under side of an
_Asclepias_ leaf, it reminds one of some large eardrop; but, though the
jeweller could successfully imitate the form, he might well despair of ever
producing the clear pale-green and the ivory-black and golden marks which
so characterize it.
"The chrysalis state lasts but a short time, as is the case with all those
which are known to suspend themselves nakedly by the tail. At the end of
about the tenth day the dark colours of the future butterflies begin to
show through the delicate and transparent skin, and suddenly this skin
bursts open near the head, and the newborn butterfly gradually extricates
itself, and stretching forth its legs and clambering on to some surrounding
object, allows its moist, thickened, and contracted wings to hang
listlessly from the body."
The perfect insect appears in March and April, hibernated specimens being
met with in the spring. It is a most striking species on the wing, and one
which, when once seen, is not likely to be forgotten.