ELEPHANT HAWK-MOTH--PRIVET HAWK-MOTH--DIGGING FOR
LARVÆ--BUFF-TIPP MOTH--GOLD-TAILED MOTH--CASE FOR ITS
EGGS--CURIOUS PROPERTY OF ITS CATERPILLAR-VAPOURER
MOTH--LEAF-ROLLERS--GREEN-OAK MOTH--ITS CONSTANT
ENEMY--LEAF-MINERS--LACKEY MOTH--EGG BRACELETS.
It will be noticed that the insects mentioned in the preceding chapter
are mostly remarkable for the cocoons which they construct, and that
the peculiarities of the larva and the perfect insect are but casually
mentioned. Those, however, which will be noticed in this chapter are
chosen because there is “something rare and strange” in the habits and
manners of the creatures themselves.
As it will be more convenient to keep to the same plate as much as
possible, we still refer to plate G. On casting the eye over the objects
there depicted, the strangest and most fantastic shape is evidently that
creature which is marked 5 _a_.
The aspect of the creature is almost appalling, and it seems to glare
at us with two malignant eyes, threatening the poisoned blow which the
horrid tail seems well able to deliver.
Yet this is as harmless a creature as lives, and it can injure nothing
except the leaves of the plant on which it feeds. The eye-like spots are
not eyes at all, but simply markings on the surface of the skin, and the
formidable horn at the tail cannot scratch the most delicate skin.
The creature is in fact simply the caterpillar of a very beautiful moth,
represented in fig. 5, and called the Elephant Hawk-moth--elephant, on
account of its long proboscis, and hawk on account of its sharp hawk-like
wings and flight. The caterpillar may be found in many places, and
especially on the banks of streams, feeding on various plants, such as
the willow-herbs.
Another kind of hawk-moth is much more common than the elephant, and is
represented on plate A; the moth itself at fig. 5, and its caterpillar at
fig. 5 _a_.
This is called the Privet Hawk-moth, because the caterpillar feeds on the
leaves of that shrub. The colours of both moth and caterpillar are very
beautiful, and not unlike in character.
The bright leafy green tint of the caterpillar, and the seven
rose-coloured stripes on each side, make it a very conspicuous insect,
and raise wishes that tints so beautiful could be preserved. But as yet
it cannot be done, for even in the most successful specimens the colours
fade sadly in a day or two, and after a while there is a determination
towards a blackish brown tint that cannot be checked.
Any one, however, who wishes to try the experiment may easily do so, for
there are few privet hedges without their inhabitants, who may keep out
of sight, but can be brought tumbling to the ground by some sharp taps
administered to the stems of the bushes.
In the winter the chrysalis may be obtained by digging under privet
bushes. There the caterpillar resorts, and works a kind of cell in the
ground for its reception. It is better not to choose a frosty day for the
disinterment, or the sudden cold may kill the insect, and the seeker’s
labour be lost.
Should it be desirable to capture the larva and to keep it alive the
object can be easily attained; for the creature is hardy enough, and
privet bushes grow everywhere. In default of privet leaves, it will eat
those of the syringa and the ash. When it reaches its full growth, it
should be provided with a vessel containing earth some inches in depth.
Into this earth it will burrow, and remain there until the moth issues
forth.
Care should be taken to keep the earth rather moist, as otherwise the
chrysalis skin becomes so hard that the moth cannot break out of its
prison, and perishes miserably.
On the same plate, fig. 4, may be seen a moth of a curious shape, very
feathery about the thorax, the head being all but concealed by the dense
down, and as difficult to find as the head of a Skye-terrier, were not
its position marked by the antennæ. This is the Buff-tip Moth, so called
on account of the upper wing-tips being marked with buff-coloured scales.
The caterpillar, which is represented immediately above, and marked 4
_a_, is a very singular creature, its habits being indicated by the marks
on its skin. As soon as the young caterpillars are hatched, they arrange
themselves in regular order, much after the fashion of the dark stripes,
and so march over leaf and branch, devastating their course with the same
ease and regularity as an invading army in an enemy’s land.
When they increase to a tolerably large size, they disband their forces,
and each individual proceeds on its own course of destruction. Were
it not for the colours which they assume, these creatures would do
great damage; but the ground being yellow and the stripes black, the
caterpillars are so conspicuous that sharp-sighted birds soon find
them out, and having discovered a colony, hold revelry thereon, and
exterminate the band.
Comparatively few escape their foes and attain maturity. When they have
reached their full age, they let themselves drop from the branches, and
when they come to soft ground, bury themselves therein to await their
last change. Individuals may often be seen crossing gravel paths, which
they are unable to penetrate, and getting over the ground with such speed
and in so evident a hurry that they seem to be aware that birds are on
the watch and ichneumons awaiting their opportunity.
There is a very pretty moth covered with a downy white plumage even to
the very toes, and carrying at the extremity of its tail a tuft of golden
silky hair. From this coloured tuft, the creature bears the name of
Gold-tailed Moth. It may often be found sticking tightly to the bark of
tree stems, its glossy white wings folded roof-like over its back, and
the golden tuft just showing itself from the white wings.
This golden tuft is only found fully developed in the female moth, and
comes into use when she deposits her eggs. The moth is shown on plate E,
fig. 4.
As the eggs are laid in the summer time, they need no guard from
cold; but they do require to be sheltered from too high a degree of
temperature, and for this purpose the silken tuft is used.
At the very end of the tail the moth carries a pair of pincers, which she
can twist about in all directions; and this tool is used for the proper
settlement of the eggs. The moth, after fixing on a proper spot, pinches
off a tiny tuft of down, spreads it smoothly, lays an egg upon it, covers
it over, and finally combs the hair so as to lie evenly. And when she
has laid the full complement, she gives the whole mass some finishing
touches, like a mother tucking-in her little baby in the bed-clothes, and
smoothing them neatly over it.
The egg masses are common enough, and are readily discovered by means of
their bright yellow covering.
The caterpillar of this moth is a very brilliant scarlet and black
creature, commonly known by the name of the “palmer-worm,” and to be
found plentifully of all sizes.
People possessed of delicate skins must beware of touching the
palmer-worm, or they may suffer for their temerity. I was a victim to the
creature for some time before I discovered the reason of my sufferings.
And the case was as follows.
Being much struck with the vivid colours of the caterpillar, I was
anxious to preserve some specimens, if possible, in a manner that would
retain the scarlet and black tints. One mode that seemed feasible was to
make a very small snuff-box, as ladies call a rectangular rent, in the
creature’s skin, to remove the entire vital organs, to fill the space
with dry sand, and then, when the skin was quite dry, to pour out all the
sand, leaving the empty skin.
After treating six or seven caterpillars in this fashion, I perceived a
violent irritation about my face, lips, and eyes, which only became worse
when rubbed. In an hour or so my face was swollen into a very horrid and
withal a very absurd mass of hard knobs, as if a number of young kidney
potatoes had been inserted under the skin.
Of course, I was invisible for some days, and after returning to my work,
was attacked in precisely the same manner again. This second mischance
set me thinking; and on consultation with the medical department, the
fault was attributed to the hot sand which I had been using.
So, when I went again to the work, I discarded sand, and stuffed the
caterpillars with cotton wool cut very short, like chopped straw. My
horror may be conjectured, but not imagined, when I found, for the third
time, that my face was beginning to assume its tubercular aspect.
Then I did what I ought to have done before, went to my entomological
books, and found that various caterpillars possessed this “urticating”
property, as they learnedly called it, or as I should say, that they
stung worse than nettles. Since that time, I have never touched a
palmer-worm with my fingers.
It was perhaps a proper punishment for neglecting the knowledge that
others had recorded. But I always had rather an aversion to book
entomology, and used to work out an insect as far as possible, and _then_
see what books said about it. Certainly, although not a very rapid mode
of work, yet it was a very sure one, and fixed the knowledge in the mind.
On the same plate, fig. 4 _a_, is shown the caterpillar of this moth, a
creature conspicuous from the tufts of beautifully-coloured hair which
are set on its body like camel-hair brushes.
The caterpillar spins for itself a silken nest wherein to pass its pupa
state, and in general there is nothing remarkable about the nest. But I
have one in my collection of insect habitations that is very curious.
I had caught, killed, and pinned out a large dragon-fly, and placed it in
a cardboard box for a time. Some days afterwards, a palmer-worm had been
captured, and was imprisoned in the same box. I was not aware that such
a circumstance had happened, and so did not open the box for a week or
two, when I expected to find the dragon-fly quite dry and ready for the
cabinet.
When, however, the box was opened, a curious state of matters was
disclosed. The caterpillar had not only spun its cocoon, but had shredded
up the dragon-fly’s wings, and woven them into the substance of its
cell. The glittering particles of the wing have a curious effect as they
sparkle among the silver fibres.
On plate D, fig. 3 _a_, is represented a creature whose sole claim to
admiration is its domestic virtue, for elegance or beauty it has none. It
hardly seems possible, but it is the fact, that this clumsy creature is
the female Vapourer Moth, the male being represented immediately below
fig. 3.
Why the two sexes should be so entirely different in aspect, it is not
easy to understand. The female has only the smallest imaginable apologies
for wings, and during her whole lifetime never leaves her home, seeming
to despise earth as she cannot attain air.
This moth is not obliged to form laboriously a warm habitation for her
eggs, for she places them in a silken web which she occupied in her pupal
state, and from which she never travels.
Curiously enough, her eggs are not placed within the hollow of the cocoon
as might be supposed, but are scattered irregularly and apparently at
random over its surface. Even there, though, they are warm enough, for
the cocoon itself is generally placed in a sheltered spot, so that the
eggs are guarded from the undue influence of the elements, and at the
same time protected from too rapid changes of temperature.
In the hot summer months, the leaves of trees are crowded with insects
of various kinds, which fly out in alarm when the branches are sharply
struck. Oak trees are especially insect-haunted, and mostly by one
species of moth, a figure which is given on plate B, fig. 1.
This little moth is a pretty object to the eyes, but a terrible
destructive creature when in its caterpillar state, compensating for its
diminutive size by its collective numbers. The caterpillar is one of
those called “Leaf-Rollers,” because they roll up the leaves on which
they feed, and take up their habitation within.
There are many kinds of leaf-rollers, each employing a different mode of
rolling the leaf, but in all cases the leaf is held in position by the
silken threads spun by the caterpillar.
Some use three or four leaves to make one habitation, by binding them
together by their edges. Some take a single leaf, and, fastening silken
cords to its edges, gradually contract them, until the edges are brought
together and there held. Some, not so ambitious in their tastes, content
themselves with a portion of a leaf, snipping out the parts that they
require and rolling it round.
The insect before us, however, requires an entire leaf for its
habitation, and there lies in tolerable security from enemies. There are
plenty of birds about the trees, and they know well enough that within
the circled leaves little caterpillars reside. But they do not find that
they can always make a meal on the caterpillars, and for the following
reason.
The curled leaf is like a tube open on both ends, the caterpillar lying
snugly in the interior. So, when the bird puts its beak into one end of
the tube, the caterpillar tumbles out at the other, and lets itself drop
to the distance of some feet, supporting itself by a silken thread that
it spins.
The bird finds that its prey has escaped, and not having sufficient
inductive reason to trace the silken thread and so find the caterpillar,
goes off to try its fortune elsewhere. The danger being over, the
caterpillar ascends its silken ladder, and quietly regains possession of
its home.
Myriads of these rolled leaves may be found on the oak trees, and the
caterpillars may be driven out in numbers by a sharp jar given to a
branch. It is quite amusing to see the simultaneous descent of some
hundred caterpillars, each swaying in the breeze at the end of the line,
and occasionally dropping another foot or so, as if dissatisfied with its
position.
Each caterpillar consumes about three or four leaves in the whole of its
existence, and literally eats itself out of house and home. But when
it has eaten one house, it only has to walk a few steps to find the
materials of another, and in a very short time it is newly lodged and
boarded.
The perfect insect is called the “Green Oak Moth”. The colour of its two
upper wings is a bright apple green; and as the creature generally sits
with its wings closed over its back, it harmonises so perfectly with
the green oak leaves, that even an accustomed eye fails to perceive it.
So numerous are these little moths, that their progeny would shortly
devastate a forest, were they not subject to the attacks of another
insect. This insect is a little fly of a shape something resembling that
of a large gnat; and which has, as far as I know, no English name. Its
scientific title is Empis. There are several species of this useful fly,
one attaining some size; but the one that claims our notice just at
present is the little empis, scientifically Empis Tessellata.
I well remember how much I was struck with the discovery that the empis
preyed on the little oak moths, and the manner in which they did so.
One summer’s day, I was entomologising in a wood, when a curious kind of
insect caught my attention. I could make nothing of it, for it was partly
green, like a butterfly or moth, and partly glittering like a fly, and
had passed out of reach before it could be approached. On walking to the
spot whence it had come, I found many of the same creatures flying about,
and apparently enjoying themselves very much.
A sweep of the net captured four or five; and then was disclosed the
secret. The compound creature was, in fact, a living empis, clasping in
its arms the body of an oak moth which it had killed, and into whose body
its long beak was driven. I might have caught hundreds if it had been
desirable. The grasp of the fly was wonderful, and if the creature had
been magnified to the human size, it would have afforded the very type of
a remorseless, deadly, unyielding gripe. Never did miser tighter grasp a
golden coin, than the empis fastens its hold on its green prey. Never did
usurer suck his client more thoroughly than the empis drains the life
juices from the victim moth.
He is a terrible fellow, this empis, quiet and insignificant in aspect,
with a sober brown coat, slim and genteel legs, and just a modest little
tuft on the top of his head. But, woe is me for the gay and very green
insect that flies within reach of this estimable individual.
The great hornet that comes rushing by is not half so dangerous, for all
his sharp teeth and his terrible sting. The stag-beetle may frighten our
green young friend out of his senses by his truculent aspect and gigantic
stature. But better a thousand stag-beetles than one little empis.
For when once the slim and genteel legs have come on the track of the
little moth, it is all over with him. Claw after claw is hooked on him,
gradually and surely the clasp tightens, and when once he is hopelessly
captured, out comes a horrid long bill, and drains him dry. Poor green
little moth!
Still continuing our research among the oak leaves, we shall find many of
them marked in a very peculiar manner. A white wavy line meanders about
the leaf like the course of a river, and, even as the river, increases
in width as it proceeds on its course. This effect is produced by the
caterpillar of one of the leaf-mining insects, tiny creatures, which live
between the layers of the leaf, and eat their way about it.
Of course, the larger the creature becomes, the more food it eats, the
more space it occupies, and the wider is its road; so that, although at
its commencement the path is no wider than a needle-scratch, it becomes
nearly the fifth of an inch wide at its termination. It is easy to trace
the insect, and to find it at the widest extremity of its path, either as
caterpillar or chrysalis. Often, though, the creature has escaped, and
the empty case is the only relic of its being.
There are many insects which are leaf-miners in their larval state.
Very many of them belong to the minutest known examples of the moth
tribes, the very humming bird of the moths, and, like the humming birds,
resplendent in colours beyond description. These Micro-Lepidoptera, as
they are called, are so numerous, that the study of them and their habits
has become quite a distinct branch of insect lore.
Some, again, are the larvæ of certain flies, while others are the larvæ
of small beetles. Their tastes, too, are very comprehensive, for there
are few indigenous plants whose leaves show no sign of the miner’s track,
and even in the leaves of many imported plants the meandering path may be
seen.
There are some plants, such as the eglantine, the dewberry, and others,
that are especially the haunts of these insects, and on whose branches
nearly every other leaf is marked with the winding path. I have now
before me a little branch containing seven leaves, and six of them have
been tunnelled, while one leaf has been occupied by two insects, each
keeping to his own side.
The course which these creatures pursue is very curious. Sometimes, as in
the figure on plate A, fig. 1, the caterpillar makes a decided and bold
track, keeping mostly to the central portion of the leaf.
Sometimes it makes a confused tortuous jumble of paths, so that it is not
easy to discover any definite course.
Sometimes it prefers the edges of the leaves, and skirts them with
strange exactness, adapting its course to every notch, and following the
outline as if it were tracing a plan.
This propensity seems to exhibit itself most strongly in the deeply cut
leaves. And the shape or direction of the path seems to be as property
belonging to this species of the insect which makes it; for there may be
tracks of totally distinct forms, and yet the insects producing them are
found to belong to the same species.
If the twigs of an ordinary thorn bush be examined during the winter
months, many of them will be seen surrounded with curious little objects,
called “fairy bracelets” by the vulgar, and by the learned “ova of
Clisiocampa Neustria”. These are the eggs of the Lackey Moth, and are
fastened round the twigs by the mother insect, a brown-coloured moth,
that may be found in any number at the right time.
It is wonderful how the shape of the egg is adapted to the peculiar
form into which they have to be moulded, and how perfectly they all fit
together. Each egg is much wider at the top than at the bottom; and this
increase of width is so accurately proportioned, that when the eggs are
fitted together round a branch, the circle described by their upper
surfaces corresponds precisely with that of the branch.
These eggs are left exposed to every change of the elements, and are
frequently actually enveloped in a coat of ice when a frost suddenly
succeeds a thaw. But they are guarded from actual contact with ice and
snow by a coating of varnish which is laid over them, and which performs
the double office of acting as a waterproof garment and of gluing the
eggs firmly together. So tightly do they adhere to each other, that if
the twig be cut off close to the bracelet the little egg circlet can be
slipped off entire.