THE HEMIPTERA 118
GENERAL INDEX 123
EXPLANATION OF PLATES 129
{1}AN
ELEMENTARY MANUAL
OF
NEW ZEALAND ENTOMOLOGY.
------
CHAPTER I
General Observations.
In the present chapter I propose to give a brief sketch of the general
principles of Entomology, including a rudimentary glance at the anatomy and
classification of insects; after which I think the reader will be in a
better position to study the habits and life-histories of the individual
species which follow.
The first requisite is a definition of what constitutes an INSECT.
_An Insect is an articulate animal having the body divided into three
distinct divisions_, viz., _the_ HEAD (Fig. I. A), _the_ THORAX (B), _and
the_ ABDOMEN (C). _It is furnished with three pairs of legs, and generally
has two pairs of wings, and to acquire this structure the creature passes
through several changes, termed its metamorphoses._ {2}The head exhibits no
distinct divisions, but bears the following appendages: the eyes, antennæ,
and organs of the mouth, or trophi.
The eyes are of two kinds, compound and simple. The former (Fig. I. c c)
are situated on the sides of the head above the mouth, and consist of two
large hemispheres, composed of a great number of hexagonal divisions, each
of which is a complete eye in itself. The latter (s s) are usually three in
number, and are situated on the top of the head between the compound ones.
They are, however, frequently wanting.
The antennæ (a) are two jointed organs, one of which is placed on each side
of the head, between the eyes; their functions are at present extremely
doubtful, but they are invariably found in all insects.
The organs of the mouth consist of the following: the labrum (Fig. II. 3),
or upper lip, a horny plate, closing the mouth from above; the mandibles (1
1), or upper jaws, two strong bent hooks, articulated to the head on each
side of the mouth, and opposed to one another like scissor blades; the
maxillæ (2 2), or under jaws, resembling the mandibles, but more delicately
constructed, and furnished with a pair of jointed appendages termed
maxillary palpi (5 5); and the labium (4), or lower lip, consisting of a
horny plate somewhat resembling the labrum, but provided with two jointed
appendages termed the labial palpi (6 6). All these organs are subject to
great modification in suctorial insects, which I shall notice further on,
when dealing with the differences between the various orders.
The thorax consists of three primary divisions, viz., the prothorax (Fig.
I. b), mesothorax (d), and metathorax (k). The upper surfaces of these are
termed the pronotum, mesonotum, and metanotum respectively, and the under
the prosternum, mesosternum, and metasternum; other divisions exist in some
insects, but they are not of a sufficiently {3}general character to be
noticed here. The six legs are attached to the under surface of the thorax,
a single pair to each division; they are composed of the following joints:
coxa (Fig. I. n), trochanter (o), femur (p), tibia (r), and tarsus (s).
[Illustration]
[Illustration: FIG. I.--Body of an insect (Hymenoptera), showing the
principal divisions: A, head; B, thorax; C, abdomen; _a_, antenna; _c_,
compound eyes; _m_, mandible; _s_, simple eyes; _b_, prothorax; _d_,
mesothorax; _k_, metathorax; 1W, fore-wing; 2W, hind-wing; _n_, coxa; _o_,
trochanter; _p_, femur; _r_, tibia; _t_, tarsus; 1 to 9 segments of the
abdomen.]
[Illustration: FIG. II.--Oral and digestive system of _Deinacrida
megacephala_ (this insect is drawn on Plate XVIII., fig. 2): 1, mandibles;
2, maxillæ; 3, labrum; 4, labium; 5, maxillary palpi; 6, labial palpi; 8,
oesophagus; 9, crop; 10, gizzard; 11, pancreas; 12, stomach; 13, biliary
vessels; 14, ilium; 15, colon; 16, anus.]
{4}The wings are attached to the meso- and metanotum; they consist of two
membranes traversed by numerous horny ribs (Fig. I. 1W and 2W).
The abdomen is made up of nine segments (C 1 to 9), some of which are not
infrequently wanting. It contains the organs of nutrition, circulation, and
generation.
The digestive system, the structure of which is apparent from Fig. II.,
consists of the following divisions: the throat, or oesophagus (8); the
crop (9); the gizzard, or proventriculus (10); the pancreas (11 11); the
stomach, or ventriculus (12); the biliary vessels (13 13 13); the ilium, or
little gut (14 14); and the colon (15); ending in the anus (16). In the
suctorial tribes, the crop is modified into a very peculiar organ, termed
the sucking stomach, which presents itself as a small bag, attached to the
throat by a thin tube. This bag exhausts the air from the throat, when the
insect is sucking, thus producing a vacuum therein, and causing a rapid
ascent of fluid into the stomach.
The heart of insects consists of an elongated tube lying along the back,
and termed the dorsal vessel. It is composed of a variable number of
chambers, the blood being driven forward towards the head by its
contractions. These motions may be easily seen in transparent species.
The breathing organs are distributed throughout the body in the form of
numerous minute air-tubes, which are supplied with air from a variable
number of apertures, situated on the sides of the insect, and termed
spiracles.
The nervous system consists of a chain of ganglia, running down the ventral
surface of the insect, and analogous to the spinal cord of higher animals.
The number of ganglia varies greatly among the different tribes.
The metamorphosis of insects, which I have previously mentioned as one of
their most essential attributes, consists of four distinct stages, _viz._,
the Egg, Larva, Pupa, and Imago.
{5}The eggs of these animals exhibit a great diversity in shape among the
different species. They are deposited by the parent with unerring instinct
on substances suitable for the food of the larvæ, which, in the majority of
cases, is quite different from that on which she herself subsists.
The larva state immediately succeeds the egg, and is spent almost
exclusively in feeding, the insect growing at a great rate, and being
frequently compelled to change its skin.
The pupa is usually completely quiescent, the insect being at this time
quite incapable of any motion, except, perhaps, a slight twirling of its
abdomen. Exceptions to this rule occur, however, in two of the orders, in
which the pupa state does not differ materially from that preceding it.
In the imago, or perfect state, the insect appears under its final form,
with every organ completely developed.
We will now consider the seven great divisions, or Orders, into which
insects are divided, the complete knowledge of which is one of the most
important elements in the entomologist's preliminary education. I trust
that by a careful perusal of the following definitions, aided by references
to the Plates, which illustrate numerous members of each order in their
several states, the reader will be enabled to master the subject without
much difficulty.
ORDER I.--COLEOPTERA.
Wings four; the anterior pair (termed elytra) horny and opaque, the
posterior membranous, and employed in flight; mouth masticatory. The larva
a grub with or without legs, but a distinct head always present. The pupa
inactive, taking no food, the limbs of the future insect enclosed in
distinct cases, and applied closely to the body. This is the largest of the
Orders, and consists of all those insects popularly known as Beetles.
(Plates I. and II.)
{6}ORDER II.--HYMENOPTERA.
Wings four, membranous, the posterior pair being the smaller, and connected
with the anterior during flight by a row of minute hooklets; mouth
masticatory, the maxillæ and labium being elongated, in many of the
families, into a long sucking instrument or "tongue." Metamorphosis as in
the Coleoptera. A large Order, containing the numerous tribes of Sawflies,
Bees, Wasps, Ants, and Ichneumon-flies. (Plate III.)
ORDER III.--DIPTERA.
Wings two; the posterior pair represented by two minute clubbed appendages
termed poisers; mouth a suctorial tube formed by an elongation of the
labium, enclosing within it a variable number of setæ answering to the
mandibles, &c., of biting insects. The larva without legs, a distinct head
being often absent. The pupa inactive, the limbs of the imago firmly
attached to the body, but plainly visible. Among the majority of species
included in this Order the larval skin is not cast away, but envelopes the
insect in a hard shell; the true pupa is consequently only visible on the
removal of this covering, when it is found to closely resemble those in
which no such arrangement occurs. The Order comprises the numerous Gnats
and two-winged Flies. (Plates IV., V., VI., VII.)
ORDER IV.--LEPIDOPTERA.
Wings four, generally covered with scales; the anterior pair slightly
superior in size; mouth suctorial, the maxillæ forming a spiral tongue,
which is coiled between the large labial palpi when not in use; other oral
organs rudimentary. In many instances the whole mouth and alimentary canal
are more or less obliterated, a considerable number of the species taking
no food in their {7}final state. The larvæ always possess a distinct head
and six thoracic legs, and in addition a variable number of prolegs are
often present on the abdominal segments. Pupa inactive, the limbs of the
future insect being usually indicated by lines in the integment. This Order
contains all the varied tribes of Butterflies and Moths. (Plates VIII.,
IX., X., XI., XII., XIII.)
ORDER V.--NEUROPTERA.
Wings four, of equal size, membranous, and traversed with numerous
branching ribs; the mouth masticatory, and in many instances but slightly
developed. Larva with a distinct head and three strong thoracic legs;
chiefly carnivorous. Pupa inactive; the limbs very perceptible and loosely
applied to the body, but incapable of distinct motion. A small Order,
comprising the Stoneflies, Lace-wings, Ant-lions, &c. (Plate XIV.)
ORDER VI.--ORTHOPTERA.
Wings four, of nearly equal size; the anterior pair often more or less
leathery, but with distinct veins. The larva and pupa closely resembling
the imago; the latter with rudimentary wings. In the instances where these
organs are wanting in the mature insect, the metamorphosis merely consists
of a series of moultings, and it is consequently a matter of some
difficulty to determine when the insect is full-grown. This Order is of
small extent; it includes the Earwigs, Cockroaches, Grasshoppers, Crickets,
Termites, Dragonflies, Mayflies and Perlidæ; the last four being
transferred from the Neuroptera of most authors. The minute species of
Mallophaga and Thysanura will also come under this heading. (Plates XV.,
XVI., XVII., XVIII., XIX.)
{8}ORDER VII.--HEMIPTERA.
Wings four, in some cases wholly membranous, but in a large proportion of
the families the basal portions of the anterior pair are horny, and form
protective cases for the other pair when not in use; mouth suctorial,
consisting of an elongate rostrum, enclosing four fine setæ. The larva and
pupa resemble the imago, the latter being active, with rudimentary wings.
In a few instances, a slight divergence from the parent form is shown in
the preparatory states (Cicadas, &c.). This is a small Order, containing
the Cicadas or "Singers," Bugs, Plant Lice, and all the suctorial animal
lice. (Plate XX.)
After the Orders, the divisions to be considered are the Groups, Families,
Genera and Species.
Groups are large divisions immediately subordinate to the orders, and
consist of a number of _kindred_ families. They are of great assistance to
the student in dealing with the very large Orders, such, for instance, as
the Coleoptera.
Families, again, consist of a number of allied genera, and Genera, in the
same way, of allied species.
With regard to the Families, I have in the main followed those of Professor
Westwood in his 'Modern Classification of Insects,' as most recent writers
appear very much divided in opinion as to the correct limits of these
divisions. Much diversity also prevails with respect to the proper
definitions of Genera and even Species, but I have deemed it best to follow
the authority of the latest catalogues in this matter, as any changes in
nomenclature are always liable to produce confusion.
{9}CHAPTER II
Collecting Insects.
So many excellent essays have been written on collecting insects that it
would probably be a most difficult task to supply much fresh information on
the subject; but as many of my readers may be unable to consult works
specially devoted thereto, the present chapter will, perhaps, be of some
value in showing them a few of the most convenient methods of collecting
insects in New Zealand.
Coleoptera, or Beetles, may be found almost everywhere. Overturning logs
and stones, peeling off bark, and cutting into the solid wood of trees, all
produce a great variety of species. A small axe and an iron wrench, shaped
something like a chisel, but bent round at the upper end, are the best
instruments for working old trees. The bark should be all stripped off and
examined, as well as the surface of the log underneath. The same remarks
apply to stones, which should be searched as well as the places from which
they were removed. Sacks, if left about the fields for a few weeks, often
harbour good beetles, and when found they should always be pulled up and
examined.
An umbrella, held upside down under flowering shrubs in the forest, will
often be found swarming with beetles after the plants have been sharply
tapped with a stout {10}walking-stick. The same object may be attained by
spreading a newspaper, or sheet, under the trees and then shaking them; the
beetles will fall on to the sheet, and may then be captured. The only
advantage of the umbrella is that it can be more readily used in awkward
places, such as on steep hill sides.
The dead bodies of birds and animals also contain peculiar species; they
may be held over the umbrella and shaken into it, when the inhabitants will
fall out, and can easily be obtained. Dead fish on the sea beach are often
very productive. Moss and fungi are unfailing resorts of many of the
smaller species of Coleoptera, and can be examined in the winter when the
entomologist is otherwise idle.
Beetles should always be brought home alive. The small round tin boxes sold
with Bryant and May's wax matches will be found very serviceable for this
purpose. These boxes are far better for all kinds of collecting than either
pill- or chip-boxes, as they do not break when knocked about. A separate
box should always be given to a large or rare species, but most of the
smaller kinds will travel quite safely in company, especially if a wisp of
grass or a leaf is put into the box to give them foothold.
Beetles must be killed with boiling water, and left immersed some hours
before setting. They must be pinned through either the right or left
elytron, and each collector must always keep to one side, as nothing looks
worse than to see some of the specimens pinned on the right and others on
the left side. When pinned the beetles are set on a corked board, the legs,
&c., being placed in a natural position, and retained until dry by means of
pins and pieces of paper and card. The smaller species should be mounted
with transparent gum on a neat piece of card, which can be pinned in the
store-box or cabinet with the others. The greatest care should be taken to
set {11}symmetrically, so that the limbs on the right-hand side of an
insect are in the same position as those on the left.
Hymenoptera may be captured with the ordinary butterfly-net, and are found
abundantly during the summer. The larger species are pinned through the
centre of the thorax, and set in the same way as Coleoptera, the smaller
ones on card with gum. These insects should, if possible, be made to fly
into the vessel of boiling water, as by this means they generally die with
their wings expanded, which is a great assistance when setting them. This
can usually be managed by holding the box containing the specimen
immediately over the water, and giving it a sharp tap with the finger of
the other hand.
Diptera are also captured with the net, and pinned in the same way, but
should be killed with the laurel bottle.
Lepidoptera are the most difficult of all to collect, and are at the same
time the most attractive to beginners. They may be captured with a net made
of fine gauze (mosquito net dyed green is the best material); the frame to
support the net is constructed of a piece of cane bent into a hoop, each of
the ends being supported in a forked tube shaped like a Y, and the long
tube, forming the base of the Y, is firmly fitted on to the end of a
walking-stick. This form of net is light, strong, and easily made; the only
thing requiring special attention is the Y, but this can be readily made by
any tinsmith out of two pieces of gas-pipe of different sizes, the larger
one for the stick, and the smaller one for the ends of the cane to fit
into. The collector should also be furnished with a number of small tin
boxes.[1] All this apparatus can easily be packed into an ordinary satchel.
{12}When the entomologist reaches his hunting-ground, he will mount his net
and place a number of the boxes in his left-hand coat pocket. The foliage
of all trees and shrubs should be vigorously beaten and the insects
captured as they fly out. When a moth is taken, the collector will first
turn the net half way round so as to close the entrance, and then, directly
the insect ceases fluttering, he should carefully place one of the little
boxes over it and slip on the lid. The box is then transferred to the
right-hand pocket. He will soon learn to do this without in any way
damaging the insect. On arrival at home, the insects should be immediately
killed in the laurel bottle. This is an ordinary wide-necked bottle with a
small bag of well-bruised _young_ laurel shoots at the bottom, covered with
a circular piece of card fitting accurately to the sides of the bottle.
Laurel shoots can always be obtained about the middle of October, when
several killing bottles can be prepared. They must always be wiped out
before using, and kept carefully corked. After a few hours the insects
should be tilted out of the bottle on to a tablecloth, and pinned exactly
through the centre of the thorax. The rough surface of the tablecloth
prevents them from slipping during the operation. About one-third of an
inch of pin should project below the body of the insect. If a moth or
butterfly dies with its wings folded upwards over the back, it must be
carefully picked up between the thumb and index finger of the left hand,
and the pin inserted with the corresponding fingers of the right hand. When
all are pinned they should be transferred to a tin box, lined with cork,
which has been previously well damped with water. While pinning them into
this box great care must be taken not to allow the wings to come in contact
with the damp cork. In about twenty-four hours the specimens thus treated
will be ready for setting. This process is performed by means of corked
boards of various widths for different sized {13}species. Each board has a
groove down the centre for the bodies of the insects to rest in, while the
wings are spread out on either side. They should be carefully moved
forwards with a fine-pointed needle to the desired position, and retained
by strips of tracing cloth pinned firmly down at the ends. These strips
must not be removed until the insects are thoroughly dry and ready to place
in the store-box or cabinet. In setting Lepidoptera, as with other insects,
symmetry and a natural position are the main points to be aimed at, special
care being taken that the antennæ, fore- and hind-legs, and wings, are
shown in correct positions, the middle pair of legs being of course, in the
majority of cases, hidden by the wings. It is almost needless to say that
different sized pins should be used for various insects, but this point
must be left to the discretion of the collector. Entomological pins of all
sizes can be obtained from James Gardner, of 29 Oxford Street, London. Gilt
pins are useful for many species which are liable to form verdigris on the
pins, and are universally employed by many entomologists, but are probably
not so strong as the silvered ones.
Many species of moths are only to be found at night. When working at this
time the collector must suspend a bulls-eye lantern round his neck or
waist, and can then have both arms free for capturing insects on the wing
or at blossoms. Honey mixed with a little rum, and applied with a small
brush to the trunks of trees a few minutes after sunset, will, on some
evenings, attract large numbers of valuable species, but not infrequently
it is quite unproductive. This mode of collecting has been termed
"sugaring" by entomologists, and may be employed during the whole summer.
The best blossoms for attracting insects in New Zealand are those of the
white rata,[2] which blooms in the forest from February till April, and
from which the {14}collector may generally rely on getting a rich harvest.
The insects can usually be slipped directly from the flowers into the
killing bottle.
This is much better than netting them, although occasionally one will
escape during the process. When dead the specimens should be placed in a
small tin box which has been filled with cotton-wool, packed very lightly.
In this way a large number of moths may be carried a long distance with
perfect safety, and the extremely inconvenient process of pinning them in
the field obviated. If Jahncke's patent boxes are employed it is quite
unnecessary to kill the moths in the field. They can be boxed directly from
the blossoms and taken home alive without suffering any injury.
Lepidoptera, and in fact all insects, are attracted by light, and in some
situations the collector will find that he may frequently obtain good
species by merely opening his sitting-room window and waiting for the
insects to arrive. Much of course depends on the situation of the
collector's residence and the nature of the night, which should be dark and
warm. I have occasionally tried taking a lamp into the forest to attract
insects, but have not met with much success. In swampy and flat situations,
no doubt, attracting by light would be very effective, especially if a
powerful lamp was employed, in an exposed situation, with a sheet behind
it, supported between two poles. This method has been followed with great
success by many English entomologists in the fens, but has not yet been
tried in the New Zealand swamps, where it would probably be the means of
bringing many new and interesting species to "light."
With regard to collecting members of the three remaining Orders but little
need be said. Neuroptera can be treated in the same way as Lepidoptera, but
they should be set on flat boards. The treatment of the Orthoptera will
resemble that of the Coleoptera, but the larger species will require {15}to
be stuffed with cotton-wool before setting. A few of the largest species of
the Lepidoptera must also be stuffed. For this purpose the specimens should
be placed on their backs on a piece of clean glass so that none of the
scales may be rubbed off. After the contents have been removed, a little
chalk should be introduced into the abdomen with the cotton-wool. Hemiptera
can be collected and set like Coleoptera, but some of the more delicate
species, such as the _Cicadæ_, should be killed in the laurel bottle
instead of in boiling water.
Before concluding the present chapter I should like to say a few words on
the subject of rearing insects, which the entomologist will soon learn to
regard as by far the most interesting method of acquiring specimens for his
collection.
Members of the Coleoptera are probably the most difficult insects to rear
in captivity. Their larvæ may be kept in ordinary jam-pots covered with
perforated zinc, and filled with earth or rotten wood. The carnivorous
species must, of course, be supplied with the animals on which they feed.
Beetle larvæ are often some years in attaining maturity. Many of the
Hymenoptera and some of the Diptera are parasitic on the larvæ of the
Lepidoptera; they are consequently found in rearing these insects, and
their economy should always be carefully recorded.
Lepidoptera are, perhaps, the most satisfactory insects to rear. Most of
the larvæ feed on the leaves of different plants, and all that is needed is
to keep them well supplied with fresh food.
So great a variety of cages have been devised for the rearing of
caterpillars that it would be quite impossible to describe them here. I
will therefore only give a short account of those which I have used myself,
and have found so convenient that I do not hesitate in recommending them to
those entomologists who wish not only to rear insects but to study their
habits.
{16}The cages I have been in the habit of using are made of two or three
thicknesses of cardboard bent round into a cylinder and strongly pasted
together. They may be of various sizes, from three to four inches in
diameter up to eight or ten, and constructed so that one will go inside the
other. The height should exceed the diameter by about one and a half
inches. The cylinders should be made so as to stand exactly level on a flat
surface, and they should have two rows of small openings round the sides
for the admission of air. It is a good plan to have four of these openings
in each row and place them opposite one another. They should be covered on
the inside with gauze, stiffened with green or brown paint, as the dark
colour will enable the observer to see inside more readily. A circular
piece of glass is fitted into the upper end of the cylinder, and fixed by
means of paste and paper. The base of the cage consists of two round pieces
of wood, one about half an inch smaller than the other, the smaller one
nailed exactly in the centre of the larger piece. These are made so that
the cardboard cylinder fits _accurately_ on the outside of the smaller
piece of wood. The whole cage is then neatly covered with white paper
inside and brown outside. A complete view of the interior can of course be
obtained by looking in at the top, while the cages can be stowed away one
within the other when not in use. A stone ink-bottle should be put on the
floor of each cage and filled with water, into which a sprig of the
food-plant can be introduced. Care must be taken to plug up the mouth of
the bottle, so that the larvae may not crawl down the stem of the plant
into the water and thus meet with an untimely end. This may readily be done
by means of a cork with a hole bored in it for the stem to pass through, or
a plug of moss or blotting-paper. Members of almost all the orders can be
reared in these cages, as jam-pots full of earth may easily be introduced,
in the place of the stone {17}bottle, when required for species which bury.
A circular piece of blotting-paper should be placed over the bottom of each
cage, while larvæ are feeding in them, and renewed when at all soiled. The
excrement must also be removed when the larvæ are supplied with fresh food.
As a rule, this is only necessary about twice a week, as the water will
keep most plants fresh for quite a lengthened period. When it is necessary
to remove a larva it should always be done with a fine camel-hair brush,
never with the fingers. Generally, however, it is better to allow the larvæ
themselves to crawl from the old sprig on to the new one, which they
usually do in a few hours after the food is changed. The old plants should
of course then be taken out so as to afford more room for fresh air.
Many female moths may be induced to lay their eggs in captivity, especially
if put in a box with some of the food-plant of the larva. It is extremely
instructive and interesting to rear an insect from the egg. When the young
larvæ first emerge they must be kept in a tumbler with a piece of glass put
over the top, as they might escape through the ventilators of the cages,
but they ought to be transferred immediately they are large enough. When
rearing a lot of caterpillars from a batch of eggs, care should be taken to
avoid overcrowding.
A collection of insects should always eventually be placed in a neatly
constructed cabinet. They should be arranged in rows, systematically, with
the correct names under each species, and the name of the order or group at
the commencement of each drawer. Numerous modifications in arrangement are
often needed to meet the requirements of different sized insects, but an
inspection of any good collection will at once explain the general
principles. Camphor should be pinned in the corner of each drawer or
store-box, and the whole collection fumigated with carbolic acid, or equal
parts of oil of thyme, oil of anise, {18}and spirits of wine, every six
months. These can be introduced in a watch glass containing a small
quantity of the chemicals on a pellet of cotton-wool, care being taken not
to stain the paper at the bottom of the drawer. For the same reason, while
using carbolic acid, the camphor should be taken out, as otherwise it will
"sweat." All boxes for the reception of insects must of course be lined
with cork and paper.
It is most important that an accurate record should be kept of every
specimen that is placed in the collection. This may be done by attaching to
the pin underneath each insect a small numbered label, which refers to a
book containing locality, date of capture and other particulars.
I have found it a good plan to give every species a number, and every
specimen a letter. Thus, supposing _Vanessa gonerilla_ is numbered "6," the
first specimen taken would be "6a," the second "6b," and so on, all the
specimens, perhaps, having different dates and localities. This system is
very convenient when specimens are sent away to be identified by another
entomologist, as, provided the collector always retains a single specimen
of the species which he desires named, it obviates the necessity of having
his specimens returned, the number showing at once to what species the name
refers. At least five lines should be allotted to each species in the
collection journal, and the writing should be small but distinct.
A collection formed in this manner will not only be a constant source of
pleasure to the collector and those who succeed him, but very probably of
great value in deciding many important questions in entomological science.
{19}CHAPTER III
The Coleoptera.
The observations on the natural history of the New Zealand beetles, forming
the subject of the present chapter, are much less numerous than might have
been expected from the great number of species which have been described.
The difficulties attendant on rearing these insects are, however, very
great, and it thus happens that the life-histories here given bear a
smaller proportion to the number of the Coleoptera than will be found to be
the case with the majority of the other Orders. I hope, however, that the
few details I have collected, referring to the following species, may
induce some of my readers to investigate others for themselves.
Group GEODEPHAGA.
Family _Cicindelidæ_.
_Cicindela tuberculata_ (Plate I., fig. 1, 1a larva).
This is a very abundant insect found throughout the country in all dry
situations. It delights in hot sunshine, and may be constantly observed
flying from our footsteps with great rapidity as we walk along the roads on
a hot summer's day.
Its larva (Fig. 1a) is an elongate fleshy grub, the head {20}and first
segment being horny and much flattened, and the body provided with two
large dorsal humps, each bearing at its apex a slender curved hook.
The burrows of these insects are very conspicuous, and must have been
noticed by every one, in garden paths, sandbanks, and other _dry_
situations; they are sometimes very numerous, and may be best described as
perfectly round shafts, about one line in diameter, and extending to the
depth of three or four inches, generally slightly curved at the bottom. The
sides are perfectly smooth, and the larva may be often discovered near the
mouth of its burrow, using its dorsal hooks to support it, and thus having
both legs and jaws free to dispose of the unfortunate insects that fall
into its snare. These usually consist of flies and small beetles, which
appear to be urged by curiosity to crawl down these pitfalls, and thus
bring about their own destruction. By reference to the figure it will be
seen how admirably the hollowed head and prothorax serve the purpose of a
shovel to the larva, when forming its shaft. These burrows are first
observed about the middle of November; the perfect insects coming abroad
three weeks or a month later, when they may be often seen in the
neighbourhood of their old domiciles. They are very voracious, devouring
large quantities of flies, caterpillars, and other insects, some of which
are much superior to themselves in size. On one occasion I saw a male
specimen of _Cicindela parryi_ (a species closely allied to but smaller
than _C. tuberculata_) attack a large Tortrix caterpillar, an inch and a
half in length. The beetle invariably sprang upon the back of the
caterpillar and bit it in the neck, being meanwhile flung over and over by
the larva's vigorous efforts to free itself from so unpleasant an
assailant. During the fight, which lasted fully twenty minutes, the beetle
was compelled to retire periodically to gain fresh strength to renew its
attacks, which were eventually {21}successful, the unfortunate tortrix
becoming finally completely exhausted. The beetle devoured but a very small
portion of the caterpillar, and abandoning the remainder went off in search
of fresh prey. Eight other closely allied species of _Cicindela_ are
described by Captain Broun in the "Manual of the New Zealand Coleoptera,"
but they offer no especial peculiarities, and _C. tuberculata_ may be taken
as a type of the genus.
Family CARABIDÆ.
_Pterostichus opulentus_ (Plate I., fig. 3, 3a larva).
This fine beetle is very common in most wooded situations in the Nelson
district; it may be at once distinguished from the numerous other closely
allied species by the beautiful metallic coppery tints that adorn its
thorax and elytra.
During the day it is usually discovered concealed under logs and stones,
and when disturbed, rushes into the first crevice to get out of the light.
At night time, it comes abroad to feed, killing an immense number of flies,
caterpillars, and other insects, to satisfy its voracious appetite.
Although of a most ferocious disposition, it is not wanting in maternal
affection. The female, when about to deposit her eggs, excavates a small
cavity nearly three inches square, in which they are placed. These she
broods over until hatched, and probably some little time afterwards, as I
have found a specimen close to a nest, which contained both eggs and larvæ,
and the zealous mother furiously bit at anything presented to her. The eggs
are oval in shape, quite smooth, and yellowish white in colour. The young
larva is drawn at Plate I., fig. 3a; it is remarkable for its superficial
resemblance to a small Iulus, and being found in similar situations to that
animal, its mimicry has probably some useful object. The older larva
differs chiefly in having the head and thoracic segments proportionately
{22}smaller. Twenty-one closely allied insects belonging to two genera are
described by Captain Broun in his Manual, the largest being _Pterostichus
australasiæ_, which is found in similar localities to the present species,
but is not so common.
Group HYDRADEPHAGA.
Family DYTICIDÆ.
_Colymbetes rufimanus_ (Plate I., fig. 4, 4a larva).
This insect is found plentifully in all still waters during the summer
months. Its larva is a soft elongate grub, provided with six slender
thoracic legs, and a pair of powerful mandibles. The posterior extremity of
the body is furnished with two curious appendages bearing a spiracle at the
apex of each, which the larva frequently protrudes above the surface of the
water. The air is taken in through the spiracles, and conveyed to all parts
of the body by two main air-tubes, one of which springs from each spiracle,
and branches throughout the insect in every direction. During the spring
months the larvæ may be found of various sizes in similar situations to the
imago; they are very voracious, devouring freshwater shrimps, _Ephemera_
larvæ, and occasionally, when pressed by hunger, they will even destroy
individuals of their own species for food. These they capture by means of
their powerful mandibles, retaining a firm hold of the victim until they
have consumed all the fleshy portions, the rest of the carcase being thrown
aside, and a fresh search made for more. One individual I kept for some
time, remained perpetually concealed in a small patch of green weed,
growing in the middle of its aquarium. In a short time it became surrounded
with the skeletons of small water shrimps which had been seized by the
larva as they passed by its hiding place, the unfortunate crustaceans only
discovering their enemy when it was too late. I have not yet observed the
pupa of this {23}insect, but it probably does not differ materially from
those of its European allies. Although so very different in general
appearance to the preceding insects, this beetle will be found on careful
examination to agree with them in all important respects, being only what a
ground beetle might naturally become if forced to lead an aquatic
existence. Breathing is effected in all the water beetles by the spiracles
of the abdomen, which alone are developed. The air is taken in between the
elytra and the body, and owing to the convexity of the former, a supply can
be retained sufficient to last the insect some twenty or thirty minutes.
The beetles may be often observed with the extremity of their elytra
protruded above the surface, renewing their supplies of air. On very hot
days _C. rufimanus_ may be occasionally seen flying with great rapidity far
away from its native ponds. When doing so it makes a loud humming noise,
and is a much more conspicuous object than when in the water.
Group CLAVICORNIA.
Family NITIDULIDÆ.
_Epuræa zealandica._
This curious little beetle is found abundantly in the neighbourhood of
decaying fungi, throughout the year, being most plentiful in the autumn and
early winter. Its larva is a small cylindrical grub, with the head and legs
so minute that they are scarcely perceptible, causing it to closely
resemble the maggots of many dipterous insects, occurring in similar
localities. It is generally found in the large yellow fungi, so abundant in
wet situations during the late autumn and winter months. It forms numerous
galleries through the plant in all directions, and owing to the large
amount of moisture which is usually present, these galleries are often
filled with water, so that the insect may {24}be said to be sub-aquatic in
its habits. I have not yet detected the pupa of this species, although the
discovery of a large quantity of both larvæ and perfect insects is of
everyday occurrence with the entomologist in winter.
Family ENGIDÆ.
_Dryocora Howittii_ (Plate I., fig. 6, 6a larva).
This quaint-looking little insect occurs occasionally in damp matai logs,
when in an advanced state of decay. The larva (Fig. 6a) is very flat and
thin, possessing the usual thoracic legs, which, however, are rather short.
The last segment of the abdomen is furnished with an anal proleg and a pair
of small setiform appendages. Its mode of progression is very peculiar,
resembling that of the Geometer larvæ among the Lepidoptera.
The thoracic legs are first brought to the ground, and the rest of the body
is then drawn up in an arched position close behind them. The anal proleg
then supports the insect while the anterior segments are thrust out, and
the others follow as before. This method is only employed on smooth
surfaces, the larva crawling along elsewhere in the usual manner.
The perfect beetle is a very sluggish insect, and difficult to find owing
to its colour, which closely resembles that of the wood in which it lives.
Family ENGIDÆ.
_Chætosoma scaritides_ (Plate I., fig. 2).
This insect may be at once recognized by its peculiar shape, no other New
Zealand beetle resembling it in this respect. Although tolerably common and
generally distributed, it is very seldom seen abroad, spending almost the
whole of its life concealed in the burrows of various wood-boring weevils.
Its larva, which feeds on the grubs {25}of these insects, is of a pinkish
colour, very fat and sluggish; the head and three anterior segments are
strong and horny, the legs being rather short. It undergoes its
transformation into the pupa within the weevil burrows, when the limbs of
the perfect insect can be seen folded down the breast, the wings and elytra
being much smaller than in the beetle. Specimens in all stages of existence
may be readily procured by splitting up old perforated logs which have been
long tenanted by weevils.
Group BRACHELYTRA.
Family STAPHYLINIDÆ.
_Staphylinus oculatus_ (Plate I., fig. 5).
This is the New Zealand representative of _S. olens_ or the "Devil's Coach
Horse," one of the most familiar of British beetles. It is found
occasionally in the neighbourhood of slaughter-houses, and may be at once
distinguished from any of the allied species by a large spot of brilliant
scarlet situated on each side of its head behind the eyes; this very
conspicuous feature has given it the specific name of _oculatus_. I am at
present unacquainted with the transformations of this fine insect, but they
will probably closely resemble those of the typical species (_S. olens_)
described in the majority of standard books on European Coleoptera. This
beetle may be frequently seen flying in the sunshine, when it has a most
striking appearance, owing to its large size and rapid motion. An
unpleasant odour is found to arise when it is handled, this being
noticeable in nearly all the members of the family. These beetles are
comparatively numerous in New Zealand, the genus _Philonthus_ comprising
several elongate active insects, of which _P. oeneus_ is one of the
commonest, and may be found abundantly amongst garden refuse. Others
frequent the seashore, feeding on decaying seaweed, and {26}may be noticed
flying in all directions along the coast immediately after sundown. Another
genus (_Xantholinus_) includes a number of interesting beetles found in old
weevil burrows, and probably feeding on their inmates.
Group LAMELLICORNES.
Family LUCANIDÆ.
_Dorcus punctulatus_ (Plate I., fig. 7).
An abundant species chiefly attached to the red pine tree or rimu, where it
may be found concealed beneath the scaly bark, in the angles of the trunk
near the roots. When disturbed, it folds up its legs and antennæ on its
breast, and, extending its powerful jaws, awaits the approach of the enemy,
ready to bite anything coming within its reach. These, however, are purely
defensive measures, the insect being quite harmless when left alone. The
larva is at present unknown to me. Another species, _D. reticulatus_, is a
much handsomer insect than the preceding; it may be at once recognized by
four deep impressions in the thorax, filled in with light-brown scales; the
margins of the elytra are similarly scaled, as well as four spots on each
elytron, the remainder of the beetle being dark-brown and shining. It is
generally found in totara bark, but is much scarcer than the last species.
One small specimen I possess, remarkable for its brilliant appearance, was
taken under the bark of a stunted black birch tree, over two thousand feet
above the sea-level.
Family MELOLONTHIDÆ.
_Stethaspis suturalis_ (Plate I., fig. 8, 8a larva).
This conspicuous insect occurs abundantly in all open situations. Its larva
(Fig. 8a) inhabits the earth, feeding on the roots of various plants, and
is especially abundant {27}in paddocks, where it occasionally does
considerable damage to the grass, and threatens ere long to become as great
a pest as its first cousin, the renowned Cockchaffer of England
(_Melolontha vulgaris_), whose fearful ravages need no description. It may
be taken as a typical larva of the family, the rest differing from one
another in little else than size. When full-grown it is quite as large as
the illustration, and is nearly always in the position there indicated,
owing to the size of its posterior segments and the absence of any anal
proleg, which compel it to lie always on its side. I have not yet succeeded
in obtaining the pupa of this insect, although larvæ may be frequently
found enclosed in oval cells, evidently about to undergo their
transformation. Several of these have been kept in captivity, but they have
hitherto always died without undergoing any change. I have, however, no
doubt as to its being the larva of _S. suturalis_, as there are no other
large Lamellicorns found near Wellington to which it could possibly be
referred. The perfect beetle appears in great numbers from November to
March; it is best taken at dusk, when it flies with a loud humming noise,
about four feet above the ground. If knocked down it always falls amongst
the herbage, and is not readily perceived until a few minutes later, when
the humming noise is resumed as the insect again gets under weigh, and the
would-be captor must not lose time if he wishes to secure it. Occasionally
individuals are seen disporting themselves on the wing during the day, but
this must be regarded as a purely exceptional circumstance. Unlike the
majority of nocturnal Coleoptera, this insect does not appear to be
attracted by light; in fact I have never obtained any specimens by this
method, although most other night-flying beetles may be taken in goodly
numbers at the attracting lamp.
{28}Family MELOLONTHIDÆ.
_Pyronota festiva_.
This brilliant little insect is extremely abundant amongst manuka, during
the early summer. In general appearance it reminds one of a miniature
specimen of the last species, but is more elongate in form; the green
thorax and elytra are also much brighter. The latter are bordered with
flashing crimson, the legs and under surface being reddish-brown, sparsely
clothed with white hairs. A small Lamellicorn grub, found amongst refuse in
manuka thickets, is probably the larva of this insect; it is less thickened
posteriorly than that of _S. suturalis_, but otherwise closely resembles
it. The perfect insect is diurnal in its habits, flying round flowering
manuka in countless numbers on a hot day. The descent of thirty or forty of
these little beetles on to the beating sheet, out of a single bush, is of
frequent occurrence, and is particularly noticed by the New Zealand
entomologist accustomed to the meagre supply of specimens offered in the
majority of instances.
Group STERNOXI.
Family ELATERIDÆ.
_Thoramus wakefieldi_ (Plate II., fig. 1, 1b larva, 1a pupa).
This fine beetle may be taken under rimu bark in tolerable abundance, and
is often observed flying about at dusk during the summer. Its larva
inhabits rotten wood, usually selecting the red pine, in which it excavates
numerous flat galleries near the surface of the logs. When disturbed it is
very sluggish, the head being immediately withdrawn into the large thoracic
segment and completely concealed. The legs are very minute, and are of but
little use in walking, the insect being chiefly dependent for locomotion on
its large anal proleg, which is furnished with numerous horny spines. When
full-grown this larva closes up one end of {29}its burrow, and thus forms a
closed cell, in which it is transformed into the pupa shown at Fig. 1a,
remaining in this condition until the warmer weather calls the insect from
its retreat. Two closely allied species are _T. perblandus_ and _Metablax
acutipennis_. The former is occasionally found under the large scales on
matai trees, and resembles the present insect in general appearance, but is
much smaller and more elongate in form, its elytra being also ornamented
with longitudinal rows of yellowish-brown hairs. The latter may be often
taken on the wing in the hottest sunshine, and is chiefly remarkable for
its elongate prothorax and pointed elytra; its colour is dark
reddish-brown, ornamented with a few scattered white hairs. All these
insects possess the singular habit of leaping into the air when placed on
their backs, the last-named species exercising this faculty in a most
marked degree. The movement is effected by the joint between the pro- and
meso-thorax, the sternum of the former being elongated into a long process,
fitting into a corresponding cavity in the latter, so that by means of the
two being suddenly brought together, the insect is thrown high into the air
with a loud clicking sound, hence the English name of the Skipjack or Click
Beetles, the scientific name, Elater, doubtless having reference to the
same habit. The object of this curious arrangement is in all probability
twofold; the sharp click and rapid movement of the insect deterring many
enemies from attacking it, whilst the short legs of the beetle, which are
quite unable to reach the ground when it is thrown on its back, render a
special contrivance necessary.
Group HETEROMERA.
Family TENEBRIONIDÆ.
_Uloma tenebrionides_ (Plate II., fig. 2, 2a larva, 2b pupa).
One of our commonest beetles, found in great abundance {30}in all moist
wood when much decayed, the favourite trees being apparently rimu and
matai. Its cylindrical larva may be taken in similar situations, and much
resembles in general appearance the well-known "wire-worm" of England,
whose destructive habits, however, it does not share. At present, whilst
bush-clearing is going on, its influence is beneficial, as it devours large
quantities of useless wood, which is thus rapidly broken up and got rid of.
The pupa is enclosed in an oval cell, constructed by the larva before
changing, from which the perfect insect emerges in due course. When first
exuded its colour is pale red, but this rapidly changes into dark brown
after the insect has been hardened by exposure to the air. Specimens are
often met with of every intermediate shade, and are rather liable to
deceive the beginner, who mistakes them for distinct species. An account of
a small Dipterous insect infesting this beetle in its preparatory states
will be found on page 62.
Group LONGICORNIA.
Family PRIONIDÆ.
_Prionus reticularis_ (Plate II., fig. 3, 3b larva, 3a pupa).
This is the largest species of beetle found in New Zealand, and is common
throughout the summer in the neighbourhood of forests. Its larva (Fig. 3b)
is a large, fat grub, with minute legs; it inhabits rimu and matai, logs,
often committing great ravages on sound timber although frequently eating
that which is decayed; posts, rails, and the rafters of houses alike suffer
from its attacks; the great holes formed by a full-grown larva of this
insect creating rapid destruction in the largest timbers. It may be
remarked, in connection with these wood-boring species, that a good thick
coat of paint put on the timber as soon as it is exposed, and renewed at
frequent intervals, to a great extent prevents their attacks. The pupa
(Fig. 3a) {31}is enclosed in one of the burrows formed by the larva, which,
before changing, blocks up any aperture, so as to rest secure from all
enemies. The perfect insect emerges in the following summer, when it may be
often observed flying about at night. It is greatly attracted by light, and
this propensity frequently leads it on summer evenings to invade ladies'
drawing-rooms, when its sudden and noisy arrival is apt to cause much
needless consternation amongst the inmates.
Closely allied to the above is _Ochrocydus huttoni_, which may be at once
known by its smaller size and plain elytra; it is very much scarcer than
_P. reticularis_, but may occasionally be cut out of dead manuka trees in
company with its larva.
Group RHYNCOPHORA.
Family CURCULIONIDÆ.
_Oreda notata_ (Plate II., fig. 4, 4a larva).
This weevil is not often noticed in the open, but may be found in great
abundance in the dead stems of fuchsia, mahoe, and other soft-wooded
shrubs, whose trunks are frequently noticed pierced with numerous
cylindrical holes. The larva also inhabits these burrows, devouring large
quantities of the wood; it is provided with a large head and powerful pair
of mandibles, but, in common with all other weevil larvæ, does not possess
legs of any description, the insect being absolutely helpless when removed
from its home in the wood. The pupa might also be found in similar
situations, but I have not yet observed it. The perfect insect may be cut
out of the trees throughout the year, and is occasionally taken amongst
herbage during the summer.
Family CURCULIONIDÆ.
_Psepholax coronatus_ (Plate II., fig. 5 [F], 5a [M]).
This curious species is found abundantly in the stems of {32}dead currant
trees (_Aristotelia racemosa_), in which it excavates numerous cylindrical
burrows like the last species, which it closely resembles when in the
larval state. The sexes are widely different, the elytra of the male being
furnished with the characteristic coronet of spines, which is entirely
wanting in the female. Numerous other members of this genus may be taken in
company with the present insect, and should be carefully examined, as a
correct determination of the males and females of the several species is
sadly wanted. Digging beetles out of the wood is good employment for the
entomologist in winter, when he will find that a day spent in this manner
will frequently produce as rich a harvest as one in the height of summer.
Before finally leaving the Coleoptera, I should like to direct the
attention of my readers to the immense number of interesting weevils found
in New Zealand. Chief among these is the remarkable _Lasiorhynchus
barbicornis_, a large insect furnished with a gigantic rostrum, which will
at once distinguish it from any of the rest. Other genera contain numerous
beetles, which may be found in various kinds of dead timber in company with
their larvæ, and are worthy of a more minute investigation than has at
present been given them.
{33}CHAPTER IV
The Hymenoptera.
The Hymenoptera are perhaps the most interesting order of insects, their
brilliant colours, great activity, and unparalleled instincts rendering
them alike attractive to the young collector and scientific entomologist.
They are, however, not very numerous in New Zealand, several of the most
important families being completely absent; in fact, with the exception of
the ants, there are no social Hymenoptera native to this country. The
information I here give in connection with these insects does not
adequately represent the large amount of interest which can be derived from
their investigation, and I must therefore refer the reader to those
admirable works by Sir J. Lubbock on Ants and by Huber on Bees, which
cannot fail to interest all who read them.
Family ANDRENIDÆ.
_Dasycolletes hirtipes_ (?) (Plate III., fig. 1).
This is the true native bee of New Zealand, and may be taken abundantly
during the whole of the summer. Its nest is constructed in crevices in the
bark of trees, &c., the insect very frequently selecting the spaces between
the boards of outhouses, where the loud buzzing noise {34}made by the
perfect bees when emerging from their retreat at once arrests our
attention. These nests consist of about ten oval cells, formed of clay, and
neatly smoothed within. They are all constructed by a single female, which
also provisions them with honey and pollen, depositing an egg in each. The
larva, after consuming the food, changes into a pupa, from which the
perfect insect emerges about January. If the reader will imagine a great
number of these nests closely packed together, the formation and storing of
the cells being performed by a number of sterile individuals (workers),
while the eggs are deposited by a single female (queen), he will have a
fair idea of the economy of the social bees and wasps, whose wonderful
instincts attain their maximum in the well-known hive-bee, successfully
introduced and cultivated in various parts of the country.
Closely allied to this species is _Dasycolletes purpureus_ (?) (Fig. 10),
which forms its nests in sand-banks, its cylindrical holes having a great
resemblance to the burrows of _Cincindela tuberculata_, which frequently
occur in the same situation.
Family SPHEGIDÆ.
_Pompilus fugax_ (Plate III., fig. 2).
This is a very abundant insect, and may be observed flying about on any
fine day during the summer, occasionally stopping to examine leaves and
crevices in the bark of trees, where it is looking for the unfortunate
spiders, which constitute the food of its progeny. The larva is a fat
apodal grub, and may be found in the cells constructed by the perfect
insect, which usually selects a large cylindrical hole in a log, previously
drilled out by a weevil. Into this burrow she pushes a large quantity of
spiders, which she has previously captured and paralyzed with her venomous
sting. When her nest is {35}properly provisioned she deposits an egg in it,
closes the hole with a neat plug of clay, and leaves the larva to quietly
consume its half-dead companions. Each female, no doubt, forms a large
number of these cells during the summer. While cutting up old logs for
Coleoptera, the entomologist will not infrequently come across these nests,
when the insects may be found in various stages of development.
Unfortunately, however, the sight which usually meets his eye is a large
number of legs and other fragments of spiders, the _fugax_ having long
since deserted the burrow, and being very probably engaged in forming
others in a neighbouring tree. These insects are very ferocious, and will
attack spiders which considerably exceed them in size. On one occasion I
noticed a very large one at rest in the centre of its web, which was
suddenly noticed by a passing _fugax_, which immediately sprang upon its
back, and, in spite of violent movements on the part of the spider, twisted
her abdomen dexterously round and stung her victim in the centre of the
thorax, between the insertions of the legs. This produced almost
instantaneous paralysis in the spider; but it was apparently too large for
the _fugax_ to carry away to her nest, as I saw the unfortunate creature
hanging helplessly in its web some hours after the occurrence.
Family FORMICIDÆ.
_Formica zealandica_ (Plate III., fig. 3 [M], 3a [F], 3b [N], 3c, cocoon).
This is one of our commonest ants, and may be noticed under logs and stones
throughout the year. The nest consists of a number of irregular cavities
dug out by the workers either in the ground or in soft rotten wood. Its
size varies considerably, but the societies of this species are not usually
so extensive as those of _Atta antarctica_, {36}an insect I shall have
occasion to refer to presently. The larvæ are minute apodal grubs, which
are dependent entirely on the workers for food. When full grown they spin
an oval cocoon of white silk, in which they are converted into pupæ, and
these the patient neuter ants may be observed carrying away with great
anxiety when disturbed, risking their own lives to preserve their adopted
offspring from destruction. The females, or queens, of which there are
several in each nest, do not appear to participate in these labours, but
are only instrumental in perpetuating the species, and the same remark
applies to the males. A large number of these winged males and females may
be observed in the nests about February, the general emergence taking place
during that month. At this time they leave their native homes and mount to
a great height in the air, and after sporting for some hours they re-alight
on the earth, and in a short space of time cast their wings. The neuters at
this time are said to carry them away to form fresh colonies, but I have
not carried my investigations sufficiently far to verify this in connection
with the New Zealand species.
Family FORMICIDÆ.
_Ponera castanea_ (Plate III., fig. 4 [M], 4a [N], 4b, larva).
This is a much larger species of ant than the last, but is apparently not
unlike it in habits. I have figured a male (Fig. 4) and worker (4a), the
female not differing from the latter in any great degree, except in being
provided with wings. It will be noticed, however, that the male is very
divergent. The larvæ of this insect are covered with numerous minute
spines, and may be often found in the nests; also the cocoons which they
form when full grown, these latter being of a dark brown colour, and rather
elongate. The winged insects are not frequently seen. They appear only for
a short time in February, the earlier {37}ones being invariably held
captive by the workers until the rest have emerged, when they are all
allowed to fly away and form fresh colonies as in the last species.
Family FORMICIDÆ.
_Atta antarctica_ (Plate III., fig. 5 [M], 5a [F], 5b, larva).
This is another very abundant species, found occasionally amongst rotten
wood in very large communities. Its larva, which is represented at Fig. 5b,
does not form any cocoon, the pupa being quite naked and defenceless. It is
a beautiful little object when examined with a microscope of moderate
power. The annual migration of the winged males and females of this species
usually takes place on a hot day in the last week of March, at which time I
have observed the air throughout a day's journey absolutely swarming with
these little insects. Many specimens are captured in the spiders' webs,
while the logs, fences, and ground are covered with ants in the proportion
of about ten males to one female. At other seasons of the year the winged
individuals of _Atta antarctica_ are seldom observed.
Family CHALCIDIDÆ.
_Pteromalus_ sp. (?) (Plate III., fig. 9).
This little insect was reared, in company with thirteen others of the same
species, from a pupa of _Eurigaster marginatus_ which had been procured
from a larva of _Oeceticus omnivorus_, and is consequently a true
hyperparasite.[3] Its curious habits will be better understood by the
reader after perusal of the life-histories of those two insects, which I
have given on pages 60 and 74. The method by which the females of the
Hymenoptera whose larvæ are parasitic on insects inhabiting other insects,
{38}introduce their eggs into their hosts,[4] is not at present known to
entomologists, but it seems at least probable that they are deposited in
the eggs of the parasitic Dipteron before these gain access to the
caterpillar of the moth.
Family ICHNEUMONIDÆ.
_Ichneumon sollicitorius_ (Plate III., fig. 6).
This is the most abundant of our ichneumon-flies, and may be taken amongst
herbage from August till May. Its larva is parasitic in the caterpillars of
various Noctuæ, having occurred in the following species: _Mamestra
composita_, _M. mutans_, and _M. ustistriga_. The pupa may be frequently
discovered inside that of the moth, and is quite white in its early stages,
but as age advances all the colours of the future insect can be seen
through the thin pellicle which invests it. The perfect insect makes its
escape through a circular hole, which it drills in the upper end of the
unfortunate moth pupa it has destroyed. The sexes of all ichneumon-flies
may be at once recognized by the females possessing an ovipositor[5]
differing considerably in length among the various species, but nearly
always plainly visible.
Family ICHNEUMONIDÆ.
_Ichneumon deceptus_ (Plate III., fig. 7).
This conspicuous insect is chiefly mentioned on account of a very curious
habit possessed by the females of congregating in large numbers on matai
trees, as many as fifty or sixty specimens being often found huddled
together under a single flake of the bark. The males are occasionally taken
flying in the open, but I have never seen any amongst these large
assemblages of females. Whether the {39}ichneumons are parasitic on some
insect which lives on the matai, or whether they assemble to feast on the
sweet juice occasionally exuded from its bark, it is impossible to say, but
in either case the complete absence of males is a very remarkable
circumstance.
Family ICHNEUMONIDÆ.
_Scolobates varipes_ (Plate III., fig. 8).
The larva of this little insect is parasitic on the useful larva of
_Syrphus ortas_ whose life-history is recorded on page 57. It is very
common in some instances, and must consequently destroy a considerable
number. It entirely eats the soft portions of the insect, and may
afterwards be found lying snugly within the hard empty shell of the
deceased syrphus pupa, which acts as a cocoon for it while undergoing its
own pupa state. The perfect insect may be often observed amongst herbage,
searching for syrphus larvæ to deposit its eggs in.
{40}CHAPTER V
The Diptera.
The next Order which comes under review is the Diptera, which includes all
the two-winged insects, and constitutes a most extensive Order in respect
to the number of distinct species. When, however, the numbers of
individuals of the same species are considered, it is probable that this
Order includes a greater proportion of the insect-world than all the others
put together. The preponderance of these insects over the rest holds good
with greater force in New Zealand than in many other countries, and this
fact may be almost inferred from the large number of spiders present here,
which are chiefly dependent on Diptera for their support. The important
function of clearing away refuse matter is almost entirely performed by the
members of this Order, as the Necrophagous Coleoptera and other scavengers
which exist in such large numbers in many countries are practically absent
here, and their work consequently devolves upon dipterous insects.
Group NEMOCERA.
Family CULICIDÆ.
_Culex iracundus_ (Plate IV., fig. 1, 1a larva, 1b pupa).
The mosquito is only too familiar to every one from {41}its ceaseless
attacks; it occurs almost everywhere, but is most abundant in marshy
situations. The larva (Fig. 1a) inhabits all stagnant waters, where it may
be found very abundantly throughout the summer, and when disturbed it
plunges about with great agility. Its food consists of the numerous
animalculæ swarming in all still waters during the greater portion of the
year. These are captured by means of two curious anterior appendages, which
are fringed with long hair, and pulled through the water like a fisherman's
net; they are then withdrawn into the mouth and the contents devoured, the
hungry insect again extending them for a fresh supply. These larvæ are
generally seen suspended from the surface of the water by the curious
air-tube which takes its rise from the penultimate segment of the abdomen,
which is of considerable length. Its apex is armed with a row of stiff
bristles, which effectually prevent the water from entering the spiracle
there situated, so that the insect is enabled to respire when hanging from
the surface, independently of any muscular action. It is also worthy of
note that the intestine discharges itself into this tube, an arrangement
which does not exist among the British species. After several moultings the
transformation to the pupa state takes place. At this stage the insect
(Fig. 1b) becomes much thickened anteriorly, this being the region of the
head and thorax of the future gnat; all the limbs are easily detected on a
close examination, as with lepidopterous pupæ. The upper portion is
provided with two short appendages, fulfilling the same function as the
air-tube of the larva, and which constantly support the pupa at the surface
of the water. The terminal fins enable it to dash through the water with
great rapidity when pursued by enemies; at other times it remains perfectly
motionless, suspended from the surface of the water. It should be mentioned
that none of these aquatic pupæ take any nourishment, neither have they any
limbs properly {42}so called. Their locomotion, although in some cases
unquestionably rapid, is entirely effected by violent motions of the
abdomen. I have been careful to point out these peculiarities as these
animals have been regarded by many authors as _active_ pupæ on a level with
those of the Orthoptera and Hemiptera. This opinion, however, is manifestly
erroneous; the pupæ of the nemocerous Diptera are on precisely the same
footing as those of the Lepidoptera, and it would be almost as reasonable
to call one of these _active_, because it wriggles out of its cocoon in the
earth before the emergence of the moth. The perfect mosquito emerges from a
rent in the thoracic shield of the pupa, drawing each pair of legs out
separately, and placing them in front of it on the water; the wings and
abdomen are then extracted and in a few moments it flies away.
The bites of these insects appear to distress some people much more than
others, probably owing to constitutional differences. I should mention that
the females alone engage in these attacks, the males being quite harmless
and subsisting entirely on honey, which is doubtless the natural food of
both sexes. The male and female mosquito are readily distinguished, the
specimen figured belonging to the latter sex; her companion is chiefly
remarkable for his plumed antennæ and beautiful palpi, which are very long
and gracefully plumed. As many of the harmless insects which will be
investigated are often mistaken for this species, and destroyed
accordingly, I should like to advise my readers that they may at once
distinguish all the venomous species of gnats by their long, lancet-like
proboscis and loud humming noise during flight.
Closely allied to this insect is _Culex argyropus_, which might be called
the coast mosquito as it is always found near the seashore, its larva
living in brackish pools just above high-water mark. The perfect insect may
be also seen skating along the surface of the water like a {43}gerris[6];
it may be at once distinguished by its dark colour,.
Family TIPULIDÆ.
_Corethra antarctica_, n.s.[7] (Plate IV., fig. 3, 3a larva, 3b pupa).
An elegant little gnat, frequenting the margins of ponds and ditches during
the spring months. The larva (Fig. 3a) is bright green, ornamented with
numerous yellow spots; it is very sluggish, living in the green slime weed
which floats on the water in such large masses during that season. Not
being very common it is difficult to find, as its colour so closely
resembles that of the weed which it always frequents. The pupa (Fig 3b), is
not very agile, and is nearly always observed suspended from the surface by
its thoracic air-tubes and caudal fins, the abdomen being directed upwards
and thus bringing the two pairs of organs close together. In its
metamorphosis and general appearance this insect forms a convenient link
between the present family and the Culicidæ.
Family TIPULIDÆ.
_Chironomus zealandicus_, n.s. (Plate IV., fig. 2, 2a larva, 2b pupa).
This is the common midge of New Zealand, and is extremely abundant
throughout the country. Its larva (Fig. 2a) inhabits the soft mud at the
bottom of stagnant ponds and streams, and is very conspicuous, being of a
brilliant crimson colour and thus much resembling the well-known
"Bloodworm" of English anglers, which is the larva of a closely allied
European species (_C. plumosus_). It may be readily kept in an aquarium,
and if supplied with a little soil and green weed will rapidly cover the
{44}walls of its glass prison with numerous tubular galleries. These take
their rise from the mud at the bottom, and, extending upwards to a distance
of three or four inches, afford the larva a convenient retreat from all
enemies. These insects are occasionally seen swimming laboriously through
the water with a peculiar zigzag motion. When out of their burrows they
have considerable difficulty in keeping beneath the surface, and may be
often observed floating helplessly with their exposed portions quite dry;
in fact the whole integment of the insect appears to have a peculiar power
of resisting the water. The pupa (Fig. 2b), is a most beautiful object, its
anterior extremity being obtusely thickened and the limbs of the future
insect quite discernible. On each side of the thorax the gills form a set
of graceful plumes, a much smaller group being also situated at the
extremity of its abdomen. In this state the insect remains almost entirely
concealed in the burrows previously constructed by the larva, its gills
imbibing sufficient air from the surrounding medium, and thus rendering
ascension to the surface unnecessary. The water is periodically circulated
in the tunnels by violent movements on the part of the pupa. About a day
before emergence the insect assumes a peculiar silvery appearance, which is
occasioned by the presence of a large quantity of air between the imago and
its pupa skin. This air has been first imbibed by the gills and afterwards
expelled through the spiracles of the enclosed gnat, thus inflating the
skin of the pupa, and helping to buoy it up during its last and most
important transformation. Leaving its tunnel the insect rises to the
surface, the thorax is lifted above the water which retreats from it on all
sides, the skin cracks open at the back and the insect slowly extricates
itself in a similar manner to the mosquito. In about ten minutes' time the
wings are sufficiently hardened for use and the insect then flies ashore,
but we may occasionally notice, {45}beside their old pupa-skins, drowned
individuals which have failed to effect a successful emergence. The perfect
insect is extremely common in all swampy situations throughout the summer;
it has a great partiality for light, and may be occasionally noticed in
vast numbers round the street lamps on a hot summer's night, especially if
rain is impending. It is a most graceful insect, and will amply repay a
minute examination (Fig. 2).
Family TIPULIDÆ.
_Ceratopogon antipodum_, n.s. (Plate IV., fig. 4, 4a larva, 4b pupa).
Very plentiful in the forest throughout the year, often enlivening the
winter sunshine by its merry gambols. The larva (Fig. 4a), is found under
the bark of newly fallen trees, feeding on the sap which exudes in large
quantities from the logs whilst drying. When first discovered it often has
a curiously spangled appearance, owing to the minute beads of moisture
retained by numerous bristles clothing the larva. When about to change,
these insects assemble in large companies of thirty or forty, firmly
affixing their basal segments to the wood, their heads all pointing inwards
and forming a small circle. In some cases, where an unusually large
gathering has occurred, a number arrange themselves into an outer row,
their heads being immediately behind the extremities of the inner group,
the whole thus bearing a rough likeness to the radiations of a star-fish.
The pupa is very short, and is furnished with two clubbed horns on the
thorax for respiration. Its abdominal portions are retained within the old
larval skin, thus keeping it firmly anchored to the log. The perfect insect
emerges from a rent in the thorax of the pupa, groups of exuviæ being of
common occurrence under the bark. The sexes differ considerably, the
individual figured {46}(Fig. 4) being a male; the female is slightly
larger, and much more stoutly built; her antennæ are filiform[8], and the
limbs generally shorter. Both are equally common, but the male is more
often noticed, owing to his greater activity.
Family TIPULIDÆ.
_Psychoda conspicillata_ (Plate IV., fig. 6).
A common species, occurring plentifully on window panes during August, and
bearing a great superficial resemblance to a small moth of the Tineina
group, often deceiving the novice in consequence. It is a beautiful object
for the microscope, the figure being a careful drawing of the insect, seen
with a power of about ten diameters. I regret to say that its
transformations are at present unknown.
Family TIPULIDÆ.
_Mycetophila antarctica_, n.s. (Plate IV., fig. 5, 5a larva, 5b pupa).
Tolerably common in the vicinity of forest during the major part of the
year. The larva (Fig. 5a), is a small elongate maggot of a pinkish colour;
it is a social insect, inhabiting rotten pine logs, which it perforates
with numerous cylindrical burrows. These larvæ, entirely confine their
attention to damp wood of a "pappy" consistency, leaving the harder logs
for the wood-boring Coleoptera, which are provided with much stronger jaws.
They consequently do not injure the rafters and boards of houses, or other
valuable timbers. The pupa (Fig. 5b) is very elongate, reposing in one of
the burrows, previously constructed by the larva. It probably breathes by
means of its spiracles, as no special organs of respiration are visible.
The perfect insect appears in a short time, flying sluggishly in the
sunshine, the female possessing an enormous abdomen, which {47}almost
incapacitates her for aerial locomotion; in other respects she resembles
the male, which is the sex figured (Fig. 5).
Family TIPULIDÆ.
_Tipula holochlora_ (Plate V., fig. 1, 1a larva, 1b pupa).
This beautiful insect is very common in the forest throughout New Zealand.
Its larva (Fig. 1a) inhabits various kinds of decaying wood, frequently
occurring in vegetable refuse at the roots of trees. It is a large,
sluggish-looking grub, and the anterior segments are very retractile. Its
colour appears to vary according to its surroundings, those specimens found
in red pine being of the dull reddish hue characteristic of that wood,
while those taken from pukatea and henau are dark brown larvæ, resembling
the illustration. These insects are very voracious, but their growth is
gradual, each larva probably occupying at least six months to reach
maturity. They mostly feed during the winter, but may be often taken at
other times. The pupa (Fig. 1b) is enclosed in a small oval cell,
previously excavated by the larva, which also constructs a ready means of
escape for the future insect in the form of a small tunnel leading out of
one end of its prison to the open air. Through this the pupa wriggles,
assisted by the spines, which arm the edges of all the segments; the
coronet of hooks at its extremity retaining the insect firmly at the mouth
of its burrow while undergoing its final transformation. After numerous
twistings and contortions on the part of the pupa, a rent is formed in the
thoracic plates, and the imago draws itself out, standing on the log until
its wings are sufficiently hardened for flight. In many old houses numbers
of these exuviæ may be seen projecting from holes in the boards--a relic of
the destruction that has taken place within. These insects naturally
inhabit dead trees, but as they will devour unsound timber in any {48}form
they are very injurious to old wooden buildings. The perfect insect chiefly
frequents forest, where it is difficult to detect owing to its green colour
harmonizing so closely with the leaves. The specimen figured (Fig. 1) is a
male, the female being considerably smaller with a much stouter body and
shorter legs.
Family TIPULIDÆ.
_Tipula fumipennis_, n.s. (Plate V., fig. 2, 2a larva, 2b pupa).
Another fine species, occurring in similar situations to the last, but not
quite so commonly. The larva (Fig. 2a) may be found throughout the year
under the bark of very rotten henau and pukatea, feeding on the moist
decaying wood. It constructs in this material numerous burrows, which are
lined with a viscous fluid constantly emitted from the mouth. Its movements
in these are very rapid, frequently eluding the most careful searches. When
divested of its slimy covering, it is anything but an offensive-looking
larva, the great air-tubes, which run the whole length of the insect, being
very conspicuous, and many of the other internal organs are easily detected
owing to its partial transparency. The pupa (Fig. 2b) is enclosed in a
small cocoon, having ready access to the air; it is chiefly remarkable for
its very large thoracic horns, which are curiously toothed. The air-tubes
connected with these are distinctly visible in the abdomen of the insect,
where they may be seen branching in all directions. When about to emerge
this pupa works its way to the surface of the log, the head and thorax are
thrust outside, and the perfect insect escapes in the ordinary way. The
illustration (Fig. 2) is taken from a female; the male differs in being
less robust, and in being provided with longer legs.
{49}Family TIPULIDÆ.
The Glow-worm. _Bolitophila luminosa_, Skuse.
(Frontispiece, fig. 1).
Every one who has walked in the forest at night has no doubt noticed, in
many damp and precipitous situations, numerous brilliant points of greenish
white light shining out from amongst the dense undergrowth. The animal
which causes this light may be seen at Fig. 1a on the Frontispiece, and is
probably one of the most interesting insects we have in New Zealand. It
inhabits irregular cavities, mostly situated in the banks of streams, where
it hangs suspended in a glutinous web which is stretched across the cavity
and supported by several smaller threads running right and left, and
attached to the sides and ends of the niche. On this the larva invariably
rests, but when disturbed immediately glides back along the main thread and
retreats into a hole which it has provided at the end of it. From the lower
side of this central thread numerous smaller threads hang down, and are
always covered with little globules of water, constituting a conspicuous,
though apparently unimportant, portion of the insect's web. It should be
mentioned that all these threads are constructed by the larva from a sticky
mucus exuded from the mouth.
The organ which emits the light can easily be seen by referring to Fig. 1a.
It is situated at the posterior extremity of the larva, and is a gelatinous
and semi-transparent structure capable of a great diversity of form. It can
be extended or withdrawn at the will of the larva, which, however, can shut
off the light independently of this latter action. Larvæ cease to shine on
very cold nights, in the daytime, and in a room which is artificially
lighted. They gleam most brilliantly on dark, damp nights, with a light
north-west wind. These larvæ appear to suffer great mortality in a state of
nature, as the {50}young ones will always be found greatly in excess of
those that are approaching maturity.
When full-grown this insect is transformed into the curious pupa shown at
Fig. 1b. It is furnished with a large process on the back of the thorax
which is attached to the web and holds the pupa suspended in the middle of
the niche previously inhabited by the larva. The light is emitted from the
posterior segment of the pupa, but is much fainter than in the larva, and a
distinct organ is not apparent. It is frequently suppressed for days
together.
The perfect insect is drawn at Fig. 1. It emits a strong light from the
posterior segment of the abdomen, about half as bright as that emanating
from a full grown larva. It has been recently described by Mr. Skuse, of
Sydney, as _Bolitophila luminosa_.
During the whole course of my observations[9] on this insect, extending
over five years, I have only succeeded in bringing two specimens to
maturity, and both of these were females.
The uses of the light and the web to the larva are at present quite unknown
to me, as well as its food, which, however, possibly consists of fungi. It
should also be mentioned that the larvæ are found in the greatest abundance
in mining tunnels, many feet below the surface of the earth, as well as in
caves.
Family TIPULIDÆ.
_Cloniophora subfasciata_ (Plate V., fig. 3, 3a larva).
Tolerably common in damp gullies during summer and autumn. The larva (Fig.
3a) inhabits decayed henau logs, {51}drilling deep into the wood, where its
burrows are seldom noticed, as they are filled up with refuse almost as
soon as they are made. The pupa resembles that of _Tipula holochlora_, but
is rather more attenuated in the body, and the thoracic horns are slightly
thicker. It is not enclosed in any cocoon, but lies amongst the powdery
wood, wriggling to the surface when about to emerge. The illustration
represents the male insect, the female having a much stouter body, with
short thick legs; she also differs in her antennæ, which are much less
branched than those of the male.
Family TIPULIDÆ.
_Rhyphus neozealandicus_ (Plate V., fig. 4, 4a larva, 4b pupa).
A most abundant species occurring in most damp situations throughout the
year. Its larva (Fig. 4a) closely resembles a small worm, being of an
elongate form attenuated at each end. The skin is very hard and of a dull
yellow colour, with black markings. The food of this insect consists of
decaying vegetable matter, which it procures by means of two small
appendages, situated on each side of the mouth, and which it is continually
moving about in search of suitable materials. The pupa is a curious object
(Fig. 4b), the two little respiratory horns having a singular resemblance
to a pair of ears. It is enclosed in a small oval cell about one inch below
the surface of the earth, the insect working its way to the air before
emergence. The perfect _Rhyphus_ may be almost regarded as one of our
domestic insects, and is seldom found in the open country, but frequents
cowhouses and other farm buildings in great numbers, the larvæ feeding on
the manure in these situations. It is often mistaken by ignorant people for
the mosquito and at once destroyed, but quite unfairly, as the species is
in reality perfectly harmless, frequently {52}benefiting mankind by the
removal of considerable quantities of effete matter, which if allowed to
remain could not fail to be injurious.
Family TIPULIDÆ.
_Bibio nigrostigma_ (Plate V., fig. 5, 5a larva, 5b pupa).
This insect is very abundant during the spring months, but rapidly
disappears, and few specimens are noticed after Christmas. Its larva (Fig.
5a) inhabits the woody powder often found under logs, which frequently
consists of the accumulated excrement of wood-boring insects. It is
gregarious in its habits, being found in large companies of fifty or a
hundred individuals. When first disturbed these appear as a wriggling mass,
but very shortly become so still that they can only be distinguished with
the greatest difficulty from morsels of bark. A considerable portion of the
powdered wood is also retained on the body of the insect by a row of short
spines situated in the middle of each segment, which helps to render the
larva still more inconspicuous. In this condition it remains for at least
eight months, during which time growth takes place very slowly. About
September the larvæ separate, each being afterwards transformed into a
small yellowish pupa (5b), whose abdominal extremity is usually retained
within the old skin, thus closely resembling that of the genus
_Ceratopogon_. I have figured this pupa entirely naked, in order to show
its characteristics, some of which are rather remarkable, more completely,
the agglutination of nearly all the anterior portions of the body being
especially noteworthy. The perfect insects may be found everywhere, the
males sucking honey from the flowers and performing many antics in the air,
often clinging hold of one another and whirling about together. The female
seldom flies, but is usually observed crawling about fences or the trunks
of trees. She may be at once recognized by her heavy body {53}which is very
large when distended with eggs. Her general colour is dull red, thus
differing widely from the male insect represented in the illustration (Fig.
5).
Family TIPULIDÆ.
_Simulia australiensis_ (Plate VI., fig. 1, 1a larva, 1b pupa).
Every one knows the sandfly, the little black insect that so persistently
perches on our hands and faces and inflicts its painful punctures, which in
many cases are followed by large swellings, often lasting for several days
and causing much irritation. Its larva (Fig. 1a) inhabits clear running
water, climbing about in strong currents by means of a pair of suckers
situated at each end of the body, two being placed on the prothoracic
segment just behind the head and two others close to the anal extremity.
These the insect employs rather curiously, the anterior pair being first
affixed and the others drawn up close behind them, its elongate body
consequently forming a loop. Clinging by the posterior suckers for a moment
the larva then reaches forward, re-affixes the anterior ones, and draws up
the posterior as before. Breathing is performed by two spiracles situated
on the last abdominal segments near the hind pair of suckers. Two large
air-tubes originate from these and run forwards, giving off branches to all
parts of the body; they terminate in a number of air-sacs in the thorax.
The food of this larva consists of animalculæ, which are no doubt obtained
by drawing the two ciliated appendages rapidly through the water several
times in succession, their contents being afterwards gathered up by the
smaller organs and passed into the mouth. When about to assume the pupa
state the insect covers itself with a glutinous envelope, which is firmly
joined to the under side of a leaf, the transformation taking place within
a few days. The pupa can hardly be distinguished from a small moth
chrysalis except for a pair of branching {54}filaments, which arise from
the top of the thorax and serve the purpose of gills (Fig. 1b). Before
emergence the anterior segments are projected nearly out of the cocoon from
which the perfect sandfly makes its escape, and floating to the surface of
the water ascends the stem of an aquatic plant to expand its wings. I
should here remark that as with the mosquitoes, the bloodthirsty
propensities of the present species have no doubt been acquired since the
arrival of man and other warm-blooded animals.
Group BRACHOCERA.
Family TABANIDÆ.
_Tabanus impar_ (Plate VI., fig. 6).
I have figured this fine species as a representative of a most important
family of Dipterous insects, but am at present quite unacquainted with its
life-history. It occurs plentifully on the margins of the forest throughout
the summer.
Family BOMBYLIDÆ.
_Comptosia bicolor_ (Plate VI., fig. 2).
This conspicuous species is very abundant in glades throughout the summer,
flying with great rapidity, and delighting to suck honey from the numerous
shrubs which are in blossom at that time of year. It is a social species,
and is usually found in companies of fifteen or twenty individuals, which
engage in endless dances, two insects often seizing one another on the wing
and then revolving together like a wheel in rapid motion. Their manoeuvres
in avoiding the strong gusty wind, so often prevalent in early summer, are
also interesting; the insects play upon the wing whilst the air is quiet,
but if a breeze springs up they instantly settle on the nearest bush,
rising to renew their sports when it is again calm. These flies are rather
variable in colour, some specimens being dark brown, {55}whilst others are
more or less covered with greyish-white hairs; individuals are also often
met with quite black and shining, their hirsute covering having been
completely rubbed off. The female may be at once recognized by her solid,
fleshy abdomen, that of the male being inflated by two great air-bladders,
which cause that portion of the body to appear semi-transparent when the
insect is held up to the light. The figure (2) is taken from a specimen of
the latter sex.
Closely allied to the present insect is _Comptosia virida_, n.s. (Fig. 3),
which can be at once distinguished by its brilliant green eyes and pale
grey clothing. The larva of this species is a large white maggot, rather
robust, and possessing a small head. It inhabits the dense moss growing on
the trunks of trees in the forest, feeding on the roots of these plants,
and finally forming an oval cocoon, in which it changes into the pupa shown
at Fig. 3b. The perfect insect appears in a few weeks' time, when it may be
taken in similar situations to _C. bicolor_, but in much fewer numbers.
Family ASILIDÆ.
_Sarapogon viduus_ (Plate VI., fig. 4, 4a larva, 4b pupa).
A voracious insect, frequenting all dry sand-banks and pathways throughout
the summer, and destroying the numerous minute diptera found in those
situations. These unfortunate victims are drilled through the thorax by
their destroyer, which sucks them completely dry with its long beak-like
proboscis. The larva (Fig. 4a) inhabits rotten wood, chiefly feeding upon
the moist, powdery portions. It is usually somewhat sluggish, but when
disturbed hops about with electrical rapidity. The head is very minute, and
the elongate body consists of twenty segments, a number very unusual among
larvæ, the normal number being twelve exclusive of the head. It lives for a
{56}considerable time and is finally transformed into the blunt-looking
pupa, drawn at Fig. 4b, without having previously constructed any cocoon.
From this the perfect insect emerges in a month or six weeks' time,
commencing its work of destruction as soon as its wings are hardened, which
takes place within a few hours.
Family STRATIOMIDÆ.
_Exaireta spiniger_ (Plate VI., fig. 5).
Abundant during November, when it may be taken in great numbers in the
vicinity of water. The larva is probably aquatic, but I have not yet
observed it, although its habits would, no doubt, be very interesting. The
perfect insects frequent flowers, and are generally very sluggish in their
movements.
Family ACROCERIDÆ.
_Acrocera longirostris_, n.s. (Plate VII., fig. 4).
An extraordinary and very rare species, occurring amongst white rata[10]
blossoms in February. At present I have only taken three specimens, _viz._,
two in Wellington and one in Nelson. The transformations of all the
Acroceridæ are as yet unknown.
Family SYRPHIDÆ.
_Syrphus ortas_ (Plate VII., fig. 3, 3a larva, 3b pupa).
Very common everywhere from September till May, or even later, when
specimens may be often seen basking in the winter sunshine. The larva (3a)
is a most useful insect to gardeners as it destroys an immense number of
aphides, those noxious little insects that commit such fearful ravages on
many valuable plants (see Hemiptera, page {57}120). In general appearance
this larva resembles a small green slug, with the skin much wrinkled, and
bearing at its extremity a short thick tube, which is probably the
respiratory apparatus, the four lunate holes situated at its apex being no
doubt the spiracles. These insects grow very slowly, occupying several
weeks to attain maturity. Their mode of capturing the aphides is very
curious, and is, briefly, as follows:--The larva lies in the midst of a
number of aphides, and it occasionally happens that some of them crawl over
it. On feeling an aphis touch its back the larva instantly darts out its
long, pointed head and strikes its prey with the apex, which is enveloped
in a quantity of very sticky mucus constantly ejected from the mouth. On
the aphis being thus captured the larva withdraws its head into the hinder
segments of its body and devours all the juicy portions of the aphis, whose
dry skin is afterwards thrown aside. When full-grown it slowly shrinks up
and changes into the pupa shown at Fig. 3b. In this state it is not
protected by any kind of cocoon, but lies amongst the refuse of the
aphides, near the stem of the plant. The fly emerges in a fortnight or
three weeks' time, and is very fond of hovering over and sucking honey from
the flowers, but the females may be often noticed running about plants,
probably in search of a suitable place to oviposit.[11] For an account of
_Scolobates varipes_, a species parasitic on the present insect, I refer to
page 39.
Family SYRPHIDÆ.
_Eristalis cingulatus_ (Plate VII., fig. 2).
This conspicuous insect occurs occasionally in glades in the forest about
January, but is by no means common. It is very fond of the white rata
flowers, where it may be {58}taken, if anywhere. Its life-history is at
present unknown, but no doubt resembles that of the following insect.
Family SYRPHIDÆ.
_Helophilus trilineatus_ (Plate VII., fig. 1, 1a larva, 1b pupa).
This fine species occurs abundantly in all damp situations throughout the
summer. Its larva may be found in stagnant pools and is often met with in
the mud at the bottom of ditches. Its posterior segments are enormously
elongated, forming a telescopic breathing apparatus, composed of two tubes,
the smaller of which is capable of being more or less extended at the will
of the larva, which is thus enabled to adjust the length of its breathing
tube, according to the depth of water or mud in which it happens to reside.
This peculiarity has given all these larvæ the name of rat-tailed maggots.
The other segments are very stout, each being furnished with a pair of
minute feet, and the head is also provided with two small appendages which
are supposed to be the outlets through which the exhausted air is
discharged by the larva. When mature this insect leaves the water, forming
a small oval cell in the neighbouring moist earth, in which it lies with
its long tail folded along the breast. The skin then gradually hardens, and
it is finally transformed into the pupa shown at Fig. 1b, the conical pair
of breathing-tubes on the thorax being slowly protruded from two hardly
perceptible warts, whilst the telescopic apparatus shrinks up, its
functions being at an end. A variable time, dependent upon the season,
elapses before the perfect insect makes its appearance, but prior to this
occurring, a large circular plate, forming the thorax of the pupa, is
thrust off, thus assisting the escape of the fly, which immediately ascends
a plant, or other convenient object, to dry and expand its wings (Fig. 1).
In the perfect {59}state it delights to hover in the air, darting away with
great rapidity on the approach of any enemies. It also frequently enters
houses, where its presence is at once betrayed by a peculiarly shrill noise
made while flying. The sexes of this insect differ chiefly in size, the
female (Fig. 1) being about twice as large as her companion.
Closely allied to this species are _Helophilus ineptus_, and _H.
hochstetteri_. The former is slightly smaller than _H. trilineatus_ and may
be at once distinguished by its tessellated orange-yellow and black
abdomen. It is rather local, but extremely abundant wherever found. The
latter has a superficial resemblance to some of the smaller blowflies
(_Musca_), but may be readily known by its large brownish-red
scutellum.[12] It is the commonest of the genus and may be found in great
numbers throughout the summer amongst veronica and other flowers.
Family MUSCIDÆ.
_Miltogramma mestor_ (?) (Plate VII, fig. 5).
A conspicuous species, found occasionally on forest-clad hills round
Wellington. The life-history is at present unknown, but its larva is very
possibly parasitic in some large Lepidoptera.
Family MUSCIDÆ.
_Nemorea nyctemerianus_ (Plate VII., fig. 6).
This little fly is seldom met with in the perfect state. Its larva is
parasitic on the caterpillar of _Nyctemera annulata_[13], the eggs being
deposited on the moth larva at an early age. The caterpillar grows and eats
in the ordinary way, until it has assumed the chrysalis state, when the
{60}maggot eats its way out and changes into a dark-brown pupa. In this
condition the parasite is protected by the web which was previously
constructed by the unfortunate caterpillar for its own use. The perfect fly
appears in about six weeks' time, its great agility and large white scales
rendering it very conspicuous.
Family MUSCIDÆ.
_Eurigaster marginatus_ (Plate VII., fig. 7).
Another parasitic species, its larva inhabiting the caterpillars of various
noctuæ which it destroys just before they change into the chrysalis state.
The pupa of the parasite lies in a small oval cell constructed in the earth
by its larva. A variable number of these maggots are found associated in
one host, the smaller caterpillars only harbouring a single individual,
while a large larva will frequently contain three or four. This species has
been bred from the following Lepidoptera: _Mamestra composita_, _M.
ustistriga_ and _M. mutans_. It also occurs in the curious _Oeceticus
omnivorus_, being found in the cocoons of that moth in numbers varying from
two to eleven, or even more, and it is especially interesting, as it is in
turn destroyed by a small species of _Pteromalus_ already noticed among the
Hymenoptera (page 37). The perfect insect occurs occasionally on flowers
throughout the summer.
Family MUSCIDÆ.
_Calliphora quadrimaculata_ (Plate VII., fig. 9).
This is the large blue-bottle fly of New Zealand and is found everywhere in
great abundance. Its larva feeds on decaying flesh and is of a dirty yellow
colour, measuring, when full-grown, about seven lines in length. The pupa
is buried at a considerable depth in the ground, the {61}larva having
descended before changing. The duration of this, and in fact of all the
stages of the insect, depends entirely upon the temperature, but the
females invariably deposit eggs, even during the hottest weather, and are
never ovo-viviparous like the next species, and several others of the
genus.
Family MUSCIDÆ.
_Sarcophaga læmica_ (Plate VII., fig. 10).
Another extremely abundant species having a similar history to the last,
but its powers of development are very much accelerated owing to the larva
being positively born alive. The females hover over meat and other suitable
substances, depositing a number of minute wriggling maggots thereon, not
infrequently to the great disgust of some hungry individual, who perhaps is
making his dinner off a mutton chop which the fly has selected as a home
for her offspring. These larvæ are all produced from distinct ova, which
hatch before being laid, as I have often proved, by removing them from the
insect's abdomen, and watching the young larva emerge from a minute
elliptical white egg, covered with a thin leathery skin. Every one who has
travelled in New Zealand must have noticed that, in the wildest spots,
these insects assemble in large numbers as soon as any meat is uncovered,
thus not only showing their universal distribution throughout the country,
but also that they possess a very keen sense of smell.
Two British species at least, allied to this genus, have been introduced
into New Zealand, _viz._, _Musca domestica_ and _Musca cæsar_. The former
is probably a world-wide insect, every ship teeming with it, but the latter
is at present rather scarce and is usually found in the neighbourhood of
farm-yards, where the larva feeds on {62}cow-dung. The perfect insect may
be at once known by its brilliant green colour.
Family MUSCIDÆ.
_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[14]. 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_[15] (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 [M], 3a [F], 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.
Group HETEROCERA.
Family SPHINGIDÆ.
This family is represented in New Zealand by the splendid _Sphinx
convolvuli_, an insect I am at present unacquainted with.
Family HEPIALIDÆ.
_Porina signata_ (Plate IX., 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 large _Hepialus_ larva 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 are _P.
umbraculata_, and _P. cervinata_. The former is rather smaller than _P.
signata_ and 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 it {70}from 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.
Family HEPIALIDÆ.
_Hepialus virescens_ (Plate IX., fig. 1 [M], 1a [F], 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 is _Aristotelia 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 as {71}the 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 wonderfully
{72}alike, 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.
{73}Family BOMBYCIDÆ.
_Nyctemera annulata_ (Plate IX., fig. 3 [M], 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.
{74}For an account of a Dipterous insect, parasitic in the present species,
I refer to page 59.
Family PSYCHIDÆ.
_Oeceticus omnivorus_ (Plate X., fig. 1 [M], 1a [F], 1b larva, 1c [M]
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 same {75}as 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 is {76}twisted 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 at {77}Figs. 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]
Family NOCTUIDÆ.
_Leucania nullifera_ (Plate XIII., 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.
{78}Family NOCTUIDÆ.
_Leucania atristriga_ (Plate X., 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.
Family NOCTUIDÆ.
_Erana graminosa_ (Plate X., 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.