increased to twice its former length, while very little difference is
manifest in the coloration. In from three to five days the caterpillar
has again changed its skin, doubled its length, assumed more pronounced
colors, which are diversified in some with mottlings upon back and
sides, and developed along the back, from the third to the tenth joint,
a low, broad, continuous, tuberculous ridge, cleft to the body at
the junction of the segments, the anterior edge of each joint being
depressed, the sides incurved. The third moult takes place in three or
four days more, but there is very little change from the former period.
Three or four days subsequent to this change occurs the fourth or final
moult, and in five or six days from this the larva is ready to pass
into the chrysalis state.
In its mature form the larva is about one-half of an inch in length.
The body is onisciform, flattened at base, furnished with retractile
legs, and has the back elevated into a rounded ridge, which slopes
backwards from the sixth segment. The sides are rather deeply hollowed,
and in the middle of each segment, from the third to the eleventh, is
a vertical, narrow depression. The last segments are flattened, the
last of all terminating roundly, its sides being narrowed and slightly
incurved, while the second segment is flattened, arched and bent
nearly flat over the head. Standing on the body is a ridge, tubercular
in nature, which in each segment from the third to the eleventh is
distinct and cleft to the body. In color, specimens vary. Some examples
are white, others decidedly greenish, but many have the posterior slope
of the second segment black or dark brown, while a few have most of
the back a dark brown, irregularly mottling a light ground, or with
small brown patches diffused over the back, but mostly on the anterior
segments. The entire surface is velvety. This appearance is caused by
minute stellate glossy processes, scarcely raised above the surface,
mostly six-rayed, and sending from the centre a concolored filamentous
spine a little longer than the rays. These stars are arranged in nearly
regular rows, and are light, except in the brown patches, where both
star and spine are brown. This velvet-like condition of the skin only
reveals its true composition under a magnifying glass.
On the eleventh segment, near the posterior edge of the back, is a
transverse slit, in a sub-oval spot, from which proceeds a membranous
process; and on the twelfth, on each side, is a mark like a stigma, but
a little larger, from which proceeds a membranous tube, ending in a
crown of feathery tentacles, these three special organs being exposed
or concealed at the will of the larva. The head is small, obovoid, dark
brown, and is placed at the end of a long, pale green, conical neck,
which is rectractile, both neck and head being covered by the second
segment.
Before changing to a chrysalis, the summer larvæ sometimes turn pink,
and from pink to brown, or become brown without the pink stage,
although others remain white or change to rusty brown. The body
contracts to about three-tenths of an inch and takes on a rounded form.
The chrysalis is dark-brown or yellow-brown, but varying in color, the
wing-cases being dark or green-tinted. Two sub-dorsal rows of blackish
dots are found on the abdomen, and sometimes a dark dorsal line. In
the few instances in which the butterfly emerges the same season
the duration of this stage is from thirty to sixty days, but most
chrysalids pass the winter and mature in the spring.
[Illustration: NEGLECTA BUTTERFLY.
Larva Feeding on Central Florets of Actinomeris, and Guarded by Ants.]
Now for a description of the butterfly. In general terms, the upper
side of the wings of the male is a deep azure-blue, with a delicate
terminal black border. On the apical part of the fore-wings the fringes
are black, but white and barred with black on the rest of these wings
and on the hind-wings. In the female the fore-wings have a broad,
blackish outer border, in some examples extending along the costa,
while the hind-wings have a blackish costa and a row of dark spots
along the outer margin. Usually the ground-color is a lighter blue
in the females than in the males. A pale silvery gray, with a silky
lustre, is the color of the under side of the wings, which is relieved
by a row of spots along the outer margin, each preceded by a crescent,
a curved row of elongate spots across the disk of the fore-wings, and
several spots on the basal part of the hind-wings, all the markings
being of a pale brown color. Violacea, the so-called winter form, has
the dark parts and crescents on the under side of the wings quite
prominent, but they do not, either in the outer border or in the basal
portion, coalesce. Pseudargiolus, the largest of the series, there
being but three forms in Pennsylvania, expands one and four-tenths
inches. The upper surface of the male usually has a terminal border
to the hind-wings of the same shade of blue as is visible on the
fore-wings, the middle area of the hind-wings being a little paler
than this border on the fore-wings. On the under side of the wings the
spots are much smaller than on the preceding form. Neglecta, which
resembles Pseudargiolus, and has the spots on the under surface small,
is a smaller form, never expanding more than one and one-tenth inches.
It is a summer form when there is more than one generation in a season,
ranging from Canada, through New England to West Virginia and Georgia,
and occurring also in Montana and Nevada. Violacea has a more extended
limit, being found in Alaska, British America, Ontario, Quebec, New
England to West Virginia, and Colorado, while Pseudargiolus ranges from
Wisconsin south to Tennessee, and on the east from Pennsylvania to
Georgia.
HIBERNATING BUTTERFLIES.
Early in March, and often while the snow yet lingers upon the
landscape, may be seen flying in and out among the forest-trees, or
lazily meandering along some deserted road through a thicket, the
beautiful Antiopa. Her rich crimson dress, so dark that it almost
seems black, with its buff-colored, sky-dotted border, serves to
distinguish her from her no less interesting, but smaller, sisters of
the Vanessa family of butterflies. But the Antiopas you then see are
generally ragged and shabby, which is not to be wondered at, when it is
considered that it is their last year’s dresses they wear, for late in
the preceding August they had their being, and all through the autumn
had been exposed to a hundred misfortunes or more while seeking their
living.
But with the coming of frost and of cold comes the blighting of
flowers. A feeling of torpor in consequence steals over their once
bouyant spirits, and into some crevice in a barn or a wood-pile or
stone-heap they creep, and there sleep the winter away, till the
warmth of the sun from his southward-bound journey returning sets the
brown buds a-swelling, when out of their hibernating retreats they
leisurely crawl for a flying stroll through the awakening trees. Slow
and deliberate their movements are, as though some grave and momentous
event were dependent thereon.
Never have I watched such actions, so human-like have they seemed,
than the conviction has gone home to my mind that they plainly evinced
a thought and a purpose, which had their origin, if not in a brain,
at least in one of the several ganglions which largely make up their
wonderful and somewhat complicated nervous machinery.
No matter how low in intelligence she may rank, Antiopa has
nevertheless, or all experience is at fault, some general ideas of the
time and fitness of things. From her gloomy abode in the wood-pile she
has emerged, while all the gay butterfly world, barring a few familiar
exceptions, is asleep, for a tour of investigation. Her venture is
seldom ill-timed, for the violets have preceded her, and from their
delicately curved flagons proffer her food and refreshment.
Cool and unhealthful as the mornings are at first, it is not till
the sun is nearly overhead that she leaves her retreat, for what of
plant-life exists is then, under the full force of his beams, at its
very best. Three or four hours a day, with few intervals of rest,
she is actively on wing, regaling herself with exercise and food,
thus storing little by little her body with some of the strength and
vivacity which were hers when the famine of winter overtook her and
forced her to retirement, so as the better to prepare for that work,
the propagation of her kind, which is the principal, but not the only,
aim of her existence. After four in the afternoon her presence is
scarce, as she has sought her old, or some other, place of shelter and
security.
But when the days have grown longer and warmer, and the trees are
arrayed in their livery of green, she is in the fields bright and
early, and often ere the dew has disappeared from the grass and the
flowers. The most restless of beings she now is. Anon alighting upon a
bush for a momentary rest, then off for a dozen or more rods, when the
presence of some favorite blossom meets her quick sight and invites her
to pause, which she does, but only for a second to quench her thirst.
Where willows, or elms, or poplars abound, she is more frequently seen
later on in May, but flying more slowly and sedately than ever before.
The flowers pass unheeded. She seems in a dream, in a reverie. But all
of a sudden she quickens her speed. You look for the cause. There, in
the distance, another is seen, just like her in mien, some would-be
suitor for her hand and affections. He enters his suit, he pleads his
great love, and awaits her sweet pleasure. The answer is brief, and
soon by their actions, as high up in the air they circle and circle,
caressing each other with strokes of the antennæ, the story is told
that his love has been requited. A brief honey-moon of two or three
days and the love-scene is over, and the two settle down to the prosy
realities of everyday life. The male goes back to his old-time pursuit
of rifling the flowers of their honeyed treasures, whilst the female,
upon whom devolves the duty of providing for the offspring whom she
is never likely to see, looks scrutinizingly about for her favorite
trees, the poplar, the elm, or the willow. In her selection of a tree
a wonderfully keen discernment is shown, for she seldom, if ever,
mistakes her plant-species.
[Illustration: MOURNING-CLOAK BUTTERFLY.
Larva Feeding on Willow Leaf, and Chrysalis Suspended from Twig.]
When a choice has been made, no time is expended in fruitless endeavor.
She proceeds at once to deposit her eggs. They are laid in a cluster
round the twig, and near the petiole of a young leaf, upon which the
newly-hatched larvæ are to feed. The eggs hatch inside of a week into
small black spiny caterpillars which, in their early stages, are very
social in their habits. Just before the final skin-moulting they
separate, each caterpillar living alone, the necessity for food, which
their very vigorous appetites now demand, being the impelling motive.
In a state of maturity the larvæ are two inches in length. They are
black, and minutely dotted with white, which gives them a greyish look.
A row of brick-red spots are found down the back, and their body is
armed with many black, rather long and slightly branching spines. The
head is black, and roughened with small black tubercles.
Having completed their period of feeding, which they do in about four
weeks, the caterpillars attach themselves by means of their tails to
a fence-rail, a window-ledge, or some such place, and pass into the
chrysalis state, which is accomplished in about four days. In this
condition they present an odd-looking appearance. The head will be
found to be deeply notched, or furnished with two ear-like prominences.
The sides are very angular. In the middle of the thorax there is a thin
projection, somewhat like a Roman nose in profile, while on the back
are two rows of very sharp tubercles of a tawny color, which contrast
very markedly in coloration with the dark-brown of the rest of the
chrysalis. Fifteen days, when the weather is favorable, are sufficient
for the development of the imago, or butterfly. As maturity approaches,
the chrysalis-shell becomes quite soft, and the efforts of the imago
to free itself from this covering are facilitated by the ejection of a
blood-red fluid, which rots the case, while it acts, at the same time,
as a lubricant to the emerging butterfly.
When these caterpillars are very abundant, as was the case in the
vicinity of Germantown some twenty-five years ago, every fence-rail
was hung with chrysalids, as many as a dozen being found upon a
single rail. The caterpillars even climbed up the sides of the houses
and suspended themselves from the window-ledges and the edges of the
overhanging shingles. When the butterflies emerged, great blotches
of the fluid bespattered the fences and houses as though the clouds
had rained great drops of blood. The willows and poplars were alive
with the caterpillars, and even the maples were overrun when there
came a scarcity of the leaves of the natural food-plants. Green
caterpillar-hunters were everywhere plentiful, and the writer could
have taken hundreds of specimens, but these highly-useful beetles made
a very sorry attempt in holding the enemy in check.
Two broods of the caterpillars are raised, one in June and the other
in August, but the agencies by nature employed for their destruction
so effectually accomplish their mission that hardly a season brings to
my notice a dozen full-grown larvæ. _Vanessa antiopa_, as this species
is called by the scientific student, or Mourning-Cloak by people and
amateurs, is generally found through the whole of North America. In
England, where it is popularly called the Camberwell Beauty, because
specimens were first taken near Camberwell, it is the rarest of
butterflies; while on the Continent, as in this country, it is a very
plentiful insect.
LEAF-CUTTER BEE.
Few hymenoptera of the family of bees are so little known as the
Megachilidæ, or Leaf-cutters. They are stout, thick-bodied insects,
with large, square heads, and armed with sharp, scissors-like jaws,
which admirably fit them for the work they have to do in preparing
materials for the building of their homes.
Our commonest species, _Megachile centuncularis_, is about the size of
the hive-bee. In gardens and nurseries where shrubbery abounds, it is
very prevalent, especially the female, which is readily distinguished
by a thick mass of stout, dense hair on the under side of the tail,
which serves as a carrier of pollen. The honey- and bumble-bees differ
materially from them, for they have the hind tibiæ and basal joints of
the tarsi very much broadened for that purpose.
Megachile is by no means a remarkable-looking insect. Judging from
its very humble exterior, one can hardly believe it possessed of the
wonderful intelligence, as shown in its wise provisions for its young,
which it is found to display.
Ordinarily the female, who is entrusted with the discharge of this very
essential business, places her nest in the solid earth underneath some
species of shrub. A vertical hole, three inches in depth, is dug, and
this is enlarged into a horizontal gallery, some five or six inches in
length.
You should see the little creature in her never-tiring work of
preparing material for her nest. In and out among the roses she goes,
examining each leaf with the most critical care, and only desisting
from her labor when a suitable one has been chosen. She scans it
over and over, and at last from a position on its upper or nether
surface proceeds to cut a piece just fitted for her work, which,
heavy as it seems, is seized between the legs and jaws and carried on
swiftly-agitated wings to her burrow.
[Illustration: LEAF-CUTTER BEE AT WORK.
Two Tunnels Being Filled With Leaf-Cells.]
Ten pieces or more, each differing in shape, are cut and borne away,
which the ingenious insect tailor twists and folds, the one within the
other, until is formed a funnel-like cone, whose end is narrower than
its mouth. So perfectly joined are the parts, that even when dry they
have been found to retain their form and integrity. A cake of honey
and pollen, for the use of some yet unborn Leaf-cutter, is deposited
within, and on this, in due time, is laid a single small egg. Nought
now remains but to wall up the cell. A circle of leaf, of the size of
the opening, is cut, and this is closely adjusted within the wall of
rolled-up leaves. Sometimes as many as four pieces are thus utilized.
A second cell, similarly built, is fitted to the first, and this is
succeeded by eight or ten others. When all is completed, the eggs being
laid and the cells all victualled, the hole of the shaft is closed with
the earth that was thrown out, and so carefully, too, that not a trace
of her doings remains to tell us the story.
Like other insects, Megachile is occasionally prone to change. Some
laborers while digging, one early spring-day, some thirteen years ago,
about a cluster of plants of _Spiræa corymbosa_, a species allied to
the roses and cinquefoils, came unexpectedly upon a dozen or more cells
of this insect, arranged horizontally in layers, some three or four
inches below the ground’s surface. These cells were three-fourths of
an inch in length, one-fourth in width, and formed of the leaves of
Spiræa. Six circles, of three pieces each, constituted the cell, and
these were so arranged that each succeeding circle was made to project
but slightly beyond its predecessor. Six circular pieces, larger than
seemed needful, closed up the opening of each cell. That there was a
purpose here manifested was very apparent. This purpose, as it appeared
to the writer, was the better accommodation by the hollow surface of
the cell that was to follow, and the giving of greater firmness and
security to the entire structure.
More curious, however, were some cells that were found the ensuing
year, which, in looks, resembled very closely those of Pelopæus, a
species of wasp, familiarly designated the Mud-dauber. These cells,
in numbers of three, were adherent to the rafters of a hardly-used
garret. In form, and in the peculiar combination of their pellets of
clay, they were the exact counterpart of the Mud-dauber’s. But the
curious funnel-like arrangement of leaves on the inside, so strikingly
characteristic of the Megachilidæ, was evidence of the most positive
kind that Pelopæus had nothing whatever to do with their putting
together. It bespoke a piece of work that was entirely beyond the
highest capability of her being to execute.
Each of the included leafy cells was one and one-eighth inches in
length, and just barely exceeding one-fourth in width. Elliptical
pieces of Spiræa, less in size than those previously described, but
arranged in a similar manner, composed the several structures. Within
each, a dead but perfectly-formed Megachile, encased in a cylindrical
bag of silk, was found, so that there could be no possible doubt of the
builder. That this inner fabric was the labor of some mother Megachile
admits not of a scruple, for no other bee is known to construct a nest
of like character. But what of the outer enveloping fabric of mud?
It was clearly impossible for the skill of a Megachile, who, while
certainly fitted for tunnelling the ground and for snipping circular
and elliptical pieces of suited dimensions from leaves with all a
tailor’s precision, would find herself wofully unadapted for the making
of mortar and the building of nests, in imitations of tunnels, out of
pellets of mud that had to be moulded into consistency and shape by the
jaws of the builder. Pelopæus alone, of all hymenopters, possesses the
ability and means of making such structures. Megachile, who is known
to occasionally build under the boards of the roof of a piazza, might
sometimes in her quest of a place appropriate the discarded cells of
some pre-existent Pelopæus for nesting purposes, but she runs a very
great risk in so doing, for the Mud-dauber does not always build a
fresh home for her treasures, save when there is a lack of the last
year’s structures. Old nests, when found, are put in speedy repair and
made to do as invaluable a service.
BATTLE BETWEEN ANTS.
Whilst reclining one beautiful May afternoon in the shade of an oak
that stood on the outskirts of a thicket, my attention was arrested by
the activity and bustle presented by a colony of yellow ants, which
proved to be the _Formica flava_, so common everywhere.
Scattered indiscriminately about were numberless larvæ in various
stages of growth, and not a few immobile pupæ, that had been brought up
from subterranean domiciles by thoughtful nurses, while here and there
were a dozen or more ants, but recently escaped from their mummy-cases,
basking in the sun’s warmth, preparatory to entering upon the duties of
the formicarium.
The very picture of restlessness and anxiety were these full-grown
neuters. That something was transpiring, or was about to transpire,
seemed not unlikely, for ovæ, larvæ and pupæ were being quickly carried
to places of concealment in the earth, or hustled away among the
entangling and interlacing grasses.
Looking about for the cause of all this excitement, the truth at once
became painfully apparent. Three large, burly ants, representatives of
_Formica subterranea_, a black species that is everywhere abundant in
wooded regions, had intruded their obnoxious presence into the happy
colony, bent, as it was evident, on pillage or slaughter.
Were plunder the inspiring motive, these giant invaders were not slow
to learn that their weaker kin, though lacking their strength, could
more than match them in cunning and stratagem.
Not daring to attack the foe, and being unwilling that any of their
number should be led into slavery, or suffer aught at the hands of
others, they immediately set to work to destroy all whom it was
impossible to protect.
[Illustration: BATTLE BETWEEN ANTS.
Young Destroyed by Nurses.]
Detailed as most of the neuters seemed to be in looking after the wants
of the immature, there were a few observed running hither and thither
and seizing in their jaws the newly-developed, not to bear them out of
the reach of danger, as was at first supposed, but to kill them so as
to prevent them from falling a living prey into the hands of the enemy.
Knowing the sympathy and affection which the nurses are ever wont to
cherish towards the objects of their care, this act of cruelty struck
me as something very astonishing and peculiar.
Prompted by curiosity to know the nature of the wounds thus inflicted,
I placed upon the palm of my hand one of the wounded ants, and made, by
means of a microscope, a careful examination of its injuries. Above
and below the abdomen, between the second and third segments, two deep
wounds, which met each other in the interior, were plainly to be seen.
Several cases of the kind were afterwards noticed. These were not
accidental occurrences, made through efforts to carry the young to
places of shelter. Possibly, through inexperience, accidents might
happen once in a long time, but to suppose that insects, accustomed to
handling their young as the neuters assuredly are, would be likely to
make such blunders, is too unreasonable to be entertained. Admitting
for argument’s sake that such things might occasionally occur, would
successive repetitions be expected? I apprehend not. But on the
supposition that a purpose was thereby subserved, the object had in
view warrants, it would seem, the means employed for its accomplishment.
What the purpose was it will now be my aim to show. That many animals,
tame as well as wild, are wont to destroy disabled and wounded
companions, is well established by history. In many instances the
destruction is justified to preserve the herd or pack from the close
pursuit of enemies. “Instinct or reason,” as Darwin says, “may suggest
the expelling an injured companion, lest beasts of prey, including man,
should be tempted to follow the troop.”
Audubon, in writing of the wild turkey, so abundant in his day,
observes substantially that the old males in their marches often
destroy the young by picking the head, but do not venture to disturb
the full-grown and vigorous. The feeble and immature being an
encumbrance, it is obvious that the watchfulness and attention which
they would require, were sympathy and affection the emotions by which
the males are actuated, would necessarily retard progress, and lead to
the destruction of the entire flock. Instinct or reason here operates
for individual and family good.