CEROCOMAE, MYLABRES AND ZONITES
All has not been told concerning the Meloidae, those strange
parasites, some of which, the Sitares and the Oil-beetles, attach
themselves, like the tiniest of Lice, to the fleece of various Bees to
get themselves carried into the cell where they will destroy the egg
and afterwards feed upon the ration of honey. A most unexpected
discovery, made a few hundred yards from my door, has warned me once
again how dangerous it is to generalize. To take it for granted, as
the mass of data hitherto collected seemed to justify us in doing,
that all the Meloidae of our country usurp the stores of honey
accumulated by the Bees, was surely a most judicious and natural
generalization. Many have accepted it without hesitation; and I for my
part was one of them. For on what are we to base our conviction when
we imagine that we are stating a law? We think to take our stand upon
the general; and we plunge into the quicksands of error. And behold,
the law of the Meloidae has to be struck off the statutes, a fate
common to many others, as this chapter will prove.
On the 16th of July, 1883, I was digging, with my son Emile, in the
sandy heap where, a few days earlier, I had been observing the labours
and the surgery of the Mantis-killing Tachytes. My purpose was to
collect a few cocoons of this Digger-wasp. The cocoons were turning up
in abundance under my pocket-trowel, when Emile presented me with an
unknown object. Absorbed in my task of collection, I slipped the find
into my box without examining it further than with a rapid glance. We
left the spot. Half-way home, the ardour of my search became assuaged;
and a thought of the problematical object, so negligently dropped into
the box among the cocoons, flashed across my mind.
"Hullo!" I said to myself. "Suppose it were _that_? Why not? But, no,
yes, it _is_ that; that's just what it is!"
Then, suddenly turning to Emile, who was rather surprised by this
soliloquy:
"My boy," I said, "you have had a magnificent find. It's a
pseudochrysalis of the Meloidae. It's a document of incalculable
value; you've struck a fresh vein in the extraordinary records of
these creatures. Let us look at it closely and at once."
The thing was taken from the box, dusted by blowing on it and
carefully examined. I really had before my eyes the pseudochrysalis of
some Meloid. Its shape was unfamiliar to me. No matter: I was an old
hand and could not mistake its source. Everything assured me that I
was on the track of an insect that rivalled the Sitares and the
Oil-beetles in the strangeness of its transformations; and, what was a
still more precious fact, its occurrence amid the burrows of the
Mantis-killer told me that its habits would be wholly different.
"It's very hot, my poor Emile; we are both of us pretty done. Never
mind: let's go back to our sand-hill and dig and have another search.
I must have the larva that comes before the pseudochrysalis; I must,
if possible, have the insect that comes out of it."
Success responded amply to our zeal. We found a goodly number of
pseudochrysalids. More often still, we unearthed larvae which were
busy eating the Mantes, the rations of the Tachytes. Are these really
the larvae that turn into the pseudochrysalids? It seems very
probable, but there is room for doubt. Rearing them at home will
dispel the mists of probability and replace them by the light of
certainty. But that is all: I have not a vestige of the perfect insect
to inform me of the nature of the parasite. The future, let us hope,
will fill this gap. Such was the result of the first trench opened in
the heap of sand. Later searches enriched my harvest a little, without
furnishing me with fresh data.
Let us now proceed to examine my double find. And first of all the
pseudochrysalis, which put me on the alert. It is a motionless, rigid
body, of a waxen yellow, smooth, shiny, curved like a fish-hook
towards the head, which is inflected. Under a very powerful
magnifying-glass the surface is seen to be strewn with very tiny
points which are slightly raised and shinier than the surface. There
are thirteen segments, including the head. The dorsal surface is
convex, the ventral surface flat. A blunt ridge divides the two
surfaces. The three thoracic segments bear each a pair of tiny conical
nipples, of a deep rusty red, signs of the future legs. The stigmata
are very distinct, appearing as specks of a deeper red than the rest
of the integuments. There is one pair, the largest, on the second
segment of the thorax, almost on the line dividing it from the first
segment. Then follow eight pairs, one on each segment of the abdomen
except the last, making in all nine pairs of stigmata. The last pair,
that of the eighth abdominal segment, is the smallest.
The anal extremity displays no peculiarity. The cephalic mask
comprises eight cone-shaped tubercles, dark red like the tubercles of
the legs. Six of these are arranged in two lateral rows; the others
are between the two rows. In each row of three nipples, the one in the
middle is the largest; it no doubt corresponds with the mandibles. The
length of this organism varies greatly, fluctuating between 8 and 15
millimetres.[1] Its width is from 3 to 4 millimetres.[2]
[Footnote 1: .312 to .585 inch.--_Translator's Note_.]
[Footnote 2: .117 to .156 inch.--_Translator's Note_.]
Apart from the general configuration, it will be seen that we have
here the strikingly characteristic appearance of the pseudochrysalids
of the Sitares, Oil-beetles and Zonites. There are the same rigid
integuments, of the red of a cough-lozenge or virgin wax; the same
cephalic mask, in which the future mouth-parts are represented by
faintly marked tubercles; the same thoracic studs, which are the
vestiges of the legs; the same distribution of the stigmata. I was
therefore firmly convinced that the parasite of the Mantis-hunters
could only be a Meloid.
Let us also record the description of the strange larva found
devouring the heap of Mantes in the burrows of the Tachytes. It is
naked, blind, white, soft and sharply curved. Its general appearance
suggests the larva of some Weevil. I should be even more accurate if I
compared it with the secondary larva of _Meloe cicatricosus_, of which
I once published a drawing in the _Annales des sciences
naturelles_.[3] If we reduce the dimensions considerably, we shall
have something very like the parasite of the Tachytes.
[Footnote 3: It was his essays in this periodical, on the
metamorphoses of the Sitares and Oil-beetles, that procured Fabre his
first reputation as an entomologist.--_Translator's Note_.]
The head is large, faintly tinged with red. The mandibles are strong,
bent into a pointed hook, black at the tip and a fiery red at the
base. The antennae are very short, inserted close to the root of the
mandibles. I count three joints: the first thick and globular, the
other two cylindrical, the second of these cut short abruptly. There
are twelve segments, apart from the head, divided by fairly definite
grooves. The first thoracic segment is a little longer than the rest,
with the dorsal plate very slightly tinged with russet, as is the top
of the head. Beginning with the tenth segment, the body tapers a
little. A slight scalloped rim divides the dorsal from the ventral
surface.
The legs are short, white and transparent and end in a feeble claw. A
pair of stigmata on the mesothorax, near the line of junction with the
prothorax; a stigma on either side of the first eight abdominal
segments; in all nine pairs of stigmata, distributed like those of the
pseudochrysalis. These stigmata are small, tinged with red and rather
difficult to distinguish. Varying in size, like the pseudochrysalid
which seems to come from it, this larva averages nearly half an inch
in length and an eighth of an inch in width.
The six little legs, feeble though they be, perform services which one
would not at first suspect. They embrace the Mantis that is being
devoured and hold her under the mandibles, while the grub, lying on
its side, takes its meal at its ease. They also serve for locomotion.
On a firm surface, such as the wooden top of my table, the larva can
move about quite well; it toddles along, dragging its belly, with its
body straight from end to end. On fine, loose sand, change of position
becomes difficult. The grub now bends itself into a bow; it wriggles
upon its back, upon its side; it crawls a little way; it digs and
heaves with its mandibles. But let a less crumbling support come to
its assistance; and pilgrimages of some length are not beyond its
powers.
I reared my guests in a box divided into compartments by means of
paper partitions. Each space, representing about the capacity of a
Tachytes-cell, received its layer of sand, its pile of Mantes and its
larva. And more than one disturbance arose in this refectory, where I
had reckoned upon keeping the banqueters isolated one from the other,
each at its special table. This larva, which had finished its ration
the day before, was discovered next day in another chamber, where it
was sharing its neighbour's repast. It had therefore climbed the
partition, which for that matter was of no great height, or else had
forced its way through some chink. This is enough, I think, to prove
that the grub is not a strict stay-at-home, as are the larvae of the
Sitares and the Oil-beetles when devouring the ration of the
Anthophora.
I imagine that, in the burrows of the Tachytes, the grub, when its
heap of Mantes is consumed, moves from cell to cell until it has
satisfied its appetite. Its subterranean excursions cannot cover a
wide range, but they enable it to visit a few adjacent cells. I have
mentioned how greatly the Tachytes' provision of Mantes varies.[4] The
smaller rations certainly fall to the males, which are puny dwarfs
compared with their companions; the more plentiful fall to the
females. The parasitic grub to which fate has allotted the scanty
masculine ration has not perhaps sufficient with this share; it wants
an extra portion, which it can obtain by changing its cell. If it be
favoured by chance, it will eat according to the measure of its hunger
and will attain the full development of which its race allows; if it
wander about without finding anything, it will fast and will remain
small. This would explain the differences which I note in both the
grubs and the pseudochrysalids, differences amounting in linear
dimensions to a hundred per cent and more. The rations, rare or
abundant according to the cells lit upon, would determine the size of
the parasite.
[Footnote 4: The essay on the Tachytes has not yet appeared in
English. It will form part of a volume entitled _More Hunting
Wasps_.--_Translator's Note_.]
During the active period, the larva undergoes a few moults; I have
witnessed at least one of these. The creature stripped of its skin
appears as it was before, without any change of form. It instantly
resumes its meal, which was interrupted while the old skin was shed;
it embraces with its legs another Mantis on the heap and proceeds to
nibble her. Whether simple or multiple, this moult has nothing in
common with the renewals due to the hypermetamorphosis, which so
profoundly change the creature's appearance.
Ten days' rearing in the partitioned box is enough to prove how right
I was when I looked upon the parasitic larva feeding on Mantes as the
origin of the pseudochrysalis, the object of my eager attention. The
creature, which I kept supplied with additional food as long as it
accepted it, stops eating at last. It becomes motionless, retracts its
head slightly and bends itself into a hook. Then the skin splits
across the head and down the thorax. The tattered slough is thrust
back; and the pseudochrysalis appears in sight, absolutely naked. It
is white at first, as the larva was; but by degrees and fairly rapidly
it turns to the russet hue of virgin wax, with a brighter red at the
tips of the various tubercles which indicate the future legs and
mouth-parts. This shedding of the skin, which leaves the body of the
pseudochrysalis uncovered, recalls the mode of transformation observed
in the Oil-beetles and is different from that of the Sitares and the
Zonites, whose pseudochrysalis remains wholly enveloped in the skin of
the secondary larva, a sort of bag which is sometimes loose, sometimes
tight and always unbroken.
The mist that surrounded us at the outset is dispelled. This is indeed
a Meloid, a true Meloid, one of the strangest anomalies among the
parasites of its tribe. Instead of living on the honey of a Bee, it
feeds on the skewerful of Mantes provided by a Tachytes. The
North-American naturalists have taught us lately that honey is not
always the diet of the Blister-beetles: some Meloidae in the United
States devour the packets of eggs laid by the Grasshoppers. This is a
legitimate acquisition on their part, not an illegal seizure of the
food-stores of others. No one, as far as I am aware, had as yet
suspected the true parasitism of a carnivorous Meloid. It is
nevertheless very remarkable to find in the Blister-beetles, on both
sides of the Atlantic, this weakness for the flavour of Locust: one
devours her eggs; the other a representative of the order, in the
shape of the Praying Mantis and her kin.
Who will explain to me this predilection for the Orthopteron in a
tribe whose chief, the Oil-beetle, accepts nothing but the mess of
honey? Why do insects which appear close together in all our
classifications possess such opposite tastes? If they spring from a
common stock, how did the consumption of flesh supplant the
consumption of honey? How did the Lamb become a Wolf? This is the
great problem which was once set us, in an inverse form, by the
Spotted Sapyga, a honey-eating relative of the flesh-eating Scolia.[5]
I submit the question to whom it may concern.
[Footnote 5: The essays on these will appear in the volume, entitled
_The Hunting Wasps_, aforementioned.--_Translator's Note_.]
The following year, at the beginning of June, some of my
pseudochrysalids split open transversely behind the head and
lengthwise down the whole of the median line of the back, except the
last two or three segments. From it emerges the tertiary larva, which,
from a simple examination with the pocket-lens, appears to me, in its
general features, identical with the secondary larva, the one which
eats the Tachytes' provisions. It is naked and pale-yellow, the colour
of butter. It is active and wriggles with awkward movements.
Ordinarily it lies upon its side, but it can also stand in the normal
position. The creature is then trying to use its legs, without finding
sufficient purchase to enable it to walk. A few days later, it
relapses into complete repose.
Thirteen segments, including the head, which is large, with a
quadrilateral cranium, rounded at the sides. Short antennae,
consisting of three knotted joints. Powerful curved mandibles, with
two or three little teeth at the end, of a fairly bright red. Labial
palpi rather bulky, short and with three joints, like the antennae.
The mouth-parts, labrum, mandibles and palpi are movable and stir
slightly, as though seeking food. A small brown speck near the base of
each antenna, marking the place of the future eyes. Prothorax wider
than the segments that come after it. These are all of one width and
are distinctly divided by a furrow and a slight lateral rim. Legs
short, transparent, without a terminal claw. They are three-jointed
stumps. Pale stigmata, eight pairs of them, placed as in the
pseudochrysalis, that is, the first and largest pair on the line
dividing the first two segments of the thorax and the seven others on
the first seven abdominal segments. The secondary larva and the
pseudochrysalis also have a very small stigma on the penultimate
segment of the abdomen. This stigma has disappeared in the tertiary
larva; at least I cannot detect it with the aid of a good
magnifying-glass.
Lastly, we find the same strong mandibles as in the secondary larva,
the same feeble legs, the same appearance of a Weevil-grub. The
movements return, but are less clearly marked than in the primary
form. The passage through the pseudochrysalid state has led to no
change that is really worth describing. The creature, after this
singular phase, is what it was before. The Meloes and Sitares, for
that matter, behave similarly.
Then what can be the meaning of this pseudochrysalid stage, which,
when passed, leads precisely to the point of departure? The Meloid
seems to be revolving in a circle: it undoes what it has just done, it
draws back after advancing. The idea sometimes occurs to me to look
upon the pseudochrysalis as a sort of egg of a superior organization,
starting from which the insect follows the ordinary law of
entomological phases and passes through the successive stages of
larva, nymph and perfect insect. The first hatching, that of the
normal egg, makes the Meloid go through the larval dimorphism of the
Anthrax and the Leucospis. The primary larva finds its way to the
victuals; the secondary larva consumes them. The second hatching, that
of the pseudochrysalis, reverts to the usual course, so that the
insect passes through the three customary forms: larva, nymph, adult.
The tertiary larval stage is of brief duration, lasting about a
fortnight. The larva then sheds its skin by a longitudinal rent along
the back, as did the secondary larva, uncovering the nymph, in which
we recognize the Beetle, the genus and species being almost
determinable by the antennae.
The second year's development turned out badly. The few nymphs which I
obtained about the middle of June shrivelled up without attaining the
perfect form. Some pseudochrysalids remained on my hands without
showing any sign of approaching transformation. I attributed this
delay to lack of warmth. I was in fact keeping them in the shade, on a
what-not, in my study, whereas under natural conditions they are
exposed to the hottest sun, beneath a layer of sand a few inches deep.
To imitate these conditions without burying my charges, whose progress
I wished to follow comfortably, I placed the pseudochrysalids that
remained on a layer of fresh sand at the bottom of a glass receiver.
Direct exposure to the sun was impracticable: it would have been fatal
at a period when life is subterranean. To avoid it, I tied over the
mouth of the receiver a few thicknesses of black cloth, to represent
the natural screen of sand; and the apparatus thus prepared was
exposed for some weeks to the most brilliant sunshine in my window.
Under the cloth cover, which, owing to its colour, favours the
absorption of heat, the temperature, during the day-time, became that
of an oven; and yet the pseudochrysalids persisted in remaining
stationary. The end of July was near and nothing indicated a speedy
hatching. Convinced that my attempts at heating would be fruitless, I
replaced the pseudochrysalids in the shade, on the shelves, in glass
tubes. Here they passed a second year, still in the same condition.
June returned once more and with it the appearance of the tertiary
larva, followed by the nymph. For the second time this stage of
development was not exceeded; the one and only nymph that I succeeded
in obtaining shrivelled, like those of the year before. Will these two
failures, arising no doubt from the overdry atmosphere of my
receivers, conceal from us the genus and the species of the
Mantis-eating Meloid? Fortunately, no. The riddle is easily solved by
deduction and comparison.
The only Melodiae in my part of the country which, though their habits
are still unknown, might correspond in size with either the larva or
the pseudochrysalis in question are the Twelve-pointed Mylabris and
Schaeffer's Cerocoma. I find the first in July on the flowers of the
sea scabious; I find the second at the end of May and in June on the
heads of the Iles d'Hyeres everlasting. This last date is best-suited
to explain the presence of the parasitic larva and its pseudochrysalis
in the Tachytes' burrows from July onwards. Moreover, the Cerocoma is
very abundant in the neighbourhood of the sand-heaps haunted by the
Tachytes, while the Mylabris does not occur there. Nor is this all:
the few nymphs obtained have curious antennae, ending in a full,
irregular tuft, the like of which is found only in the antennae of the
male Cerocoma. The Mylabris, therefore, must be eliminated; the
antennae, in the nymph, must be regularly jointed, as they are in the
perfect insect. There remains the Cerocoma.
Any lingering doubts may be dispelled: by good fortune, a friend of
mine, Dr. Beauregard, who is preparing a masterly work upon the
Blister-beetles, had some pseudochrysalids of Schreber's Cerocoma in
his possession. Having visited Serignan for the purpose of scientific
investigations, he had searched the Tachytes' sand-heaps in my company
and taken back to Paris a few pseudochrysalids of grubs fed on Mantes,
in order to follow their development. His attempts, like mine, had
miscarried; but, on comparing the Serignan pseudochrysalids with those
of Schreber's Cerocoma, which came from Aramon, near Avignon, he was
able to establish the closest resemblance between the two organisms.
Everything therefore confirms the supposition that my discovery can
relate only to Schaeffer's Cerocoma. As for the other, it must be
eliminated: its extreme rarity in my neighbourhood is a sufficient
reason.
It is tiresome that the diet of the Aramon Meloid is not known. If I
allowed myself to be guided by analogy, I should be inclined to regard
Schreber's Cerocoma as a parasite of _Tachytes tarsina_, who buries
her hoards of young Locusts in the high sandy banks. In that case, the
two Cerocomae would have a similar diet. But I leave it to Dr.
Beauregard to elucidate this important characteristic.
The riddle is deciphered: the Meloid that eats Praying Mantes is
Schaeffer's Cerocoma, of whom I find plenty, in the spring, on the
blossoms of the everlasting. Whenever I see it, my attention is
attracted by an unusual peculiarity: the great difference of size that
is able to exist between one specimen and another, albeit of the same
sex. I see stunted creatures, females as well as males, which are
barely one third the length of their better-developed companions. The
Twelve-spotted Mylabris and the Four-spotted Mylabris present
differences quite as pronounced in this respect.
The cause which makes a dwarf or a giant of the same insect,
irrespective of its sex, can be only the smaller or greater quantity
of food. If the larva, as I suspect, is obliged to find the Tachytes'
game-larder for itself and to visit a second and a third, when the
first is too frugally furnished, it may be imagined that the hazard of
the road does not favour all in the same way, but rather allots
abundance to one and penury to another. The grub that does not eat its
fill remains small, while the one that gluts itself grows fat. These
differences of size, in themselves, betray parasitism. If a mother's
pains had amassed the food, or if the family had had the industry to
obtain it direct instead of robbing others, the ration would be
practically equal for all; and the inequalities in size would be
reduced to those which often occur between the two sexes.
They speak, moreover, of a precarious, risky parasitism, wherein the
Meloid is not sure of finding its food, which the Sitaris finds so
deftly, getting itself carried by the Anthophora, after being born at
the very entrance to the Bee's galleries and leaving its retreat only
to slip into its host's fleece. A vagabond obliged to find for itself
the food that suits it, the Cerocoma incurs the risk of Lenten fare.
One chapter is lacking to complete the history of Schaeffer's
Cerocoma: that which treats of the beginning, the laying of the eggs,
the egg itself and the primary larva. While watching the development
of the Mantis-eating parasite, I took my precautions, in the first
year, to discover its starting-point. By eliminating what was known to
me and seeking among the Meloidae of my neighbourhood for the size
that corresponded with the pseudochrysalids unearthed from the
Tachytes' burrows, I found, as I have said, only Schaeffer's Cerocoma
and the Twelve-spotted Mylabris. I undertook to rear these in order to
obtain their eggs.
As a standard of comparison, the Four-spotted Mylabris, of a more
imposing size, was added to the first two. A fourth, _Zonitis mutica_,
whom I did not need to consult, knowing that she was not connected
with the matter in hand and being familiar with her pseudochrysalis,
completed my school of egg-layers. I proposed, if possible, to obtain
her primary larva. Lastly, I had formerly reared some Cantharides with
the object of observing their egg-laying. In all, five species of
Blister-beetles, reared in a breeding-cage, have left a few lines of
notes in my records.
The method of rearing is of the simplest. Each species is placed under
a large wire-gauze dome standing in a basin filled with earth. In the
middle of the enclosure is a bottle full of water, in which the food
soaks and keeps fresh. For the Cantharides, this is a bundle of
ash-twigs; for the Four-spotted Mylabris, a bunch of bindweed
(_Convolvus arvensis_) or psoralea (_P. biluminosa_), of which the
insect nibbles only the corollae. For the Twelve-spotted Mylabris, I
provide blossoms of the scabious (_Scabiosa maritima_); for the
Zonitis, the full-blown heads of the eryngo (_Eryngium campestre_);
for Schaeffer's Cerocoma, the heads of the Iles d'Hyeres everlasting
(_Helichrysum stoechas_). These three last nibble more particularly
the anthers, more rarely the petals, never the leaves.
A sorry intellect and sorry manners, which hardly repay the minute
cares involved in the rearing. To browse, to love her lord, to dig a
hole in the earth and carelessly to bury her eggs in it: that is the
whole life of the adult Meloid. The dull creature acquires a little
interest only at the moment when the male begins to toy with his mate.
Every species has its own ritual in declaring its passion; and it is
not beneath the dignity of the observer to witness the manifestations,
sometimes so very strange, of the universal Eros, who rules the world
and brings a tremor to even the lowest of the brute creation. This is
the ultimate aim of the insect, which becomes transfigured for this
solemn function and then dies, having no more to do.
A curious book might be written on the subject of love among the
beasts. Long ago the subject tempted me. For a quarter of a century my
notes have been slumbering, dustily, in a corner of my library. I
extract from them the following details concerning the Cantharides. I
am not the first, I know, to describe the amorous preludes of the
Meloid of the Ash-tree; but the change of narrator may give the
narrative a certain value: it confirms what has already been said and
throws light upon some points which may have escaped notice.
A female Cantharides is peacefully nibbling her leaf. A lover comes
upon the scene, approaches her from behind, suddenly mounts upon her
back and embraces her with his two pairs of hind-legs. Then with his
abdomen, which he lengthens as much as possible, he energetically
slaps that of the female, on the right side and the left by turns. It
is like the strokes of a washerwoman's bat, delivered with frenzied
rapidity. With his antennae and his fore-legs, which remain free, he
furiously lashes the neck of the victim. While the blows fall thick as
hail, in front and behind, the head and corselet of the amorous swain
are shaken by an extravagant swaying and trembling. You would think
that the creature was having an epileptic fit.
Meanwhile, the beloved makes herself small, opening her wing-cases
slightly, hiding her head and tucking her abdomen under her, as though
to escape the erotic thunderstorm that is bursting upon her back. But
the paroxysm calms down. The male extends his fore-legs, shaken by a
nervous tremor, like the arms of a cross and in this ecstatic posture
seems to call upon the heavens to witness the ardour of his desires.
The antennae and the belly are held motionless, in a straight line;
the head and the corselet alone continue to heave rapidly up and down.
This period of repose does not last long. Short as it is, the female,
her appetite undisturbed by the passionate protestations of her wooer,
imperturbably resumes the nibbling of her leaf.
Another paroxysm bursts forth. Once more the male's blows rain upon
the neck of the tightly-clasped victim, who hastens to bow her head
upon her breast. But he has no intention of allowing his lady-love to
escape. With his fore-legs, using a special notch placed at the
juncture of the leg and the tarsus, he seizes both her antennae. The
tarsus folds back; and the antennae are held as in a vice. The suitor
pulls; and the callous one is forced to raise her head. In this
posture the male reminds one of a horseman proudly sitting his steed
and holding the reins in both hands. Thus mastering his mount, he is
sometimes motionless and sometimes frenzied in his demonstrations.
Then, with his long abdomen, he lashes the female's hinder-parts,
first on one side, then on the other; the front part he flogs, hammers
and pounds with blows of his antennae, head and feet. The object of
his desires will be unfeeling indeed if she refuse to surrender to so
passionate a declaration.
Nevertheless she still requires entreating. The impassioned lover
resumes his ecstatic immobility, with his quivering arms outstretched
like the limbs of a cross. At brief intervals the amorous outbursts,
with blows conscientiously distributed, recur in alternation with
periods of repose, during which the male holds his fore-legs
crosswise, or else masters the female by the bridle of her antennae.
At last the flagellated beauty allows herself to be touched by the
charm attendant on his thumps. She yields. Coupling takes place and
lasts for twenty hours. The heroic part of the male's performance is
over. Dragged backwards behind the female, the poor fellow strives to
uncouple himself. His mate carts him about from leaf to leaf, wherever
she pleases, so that she may choose the bit of green stuff to her
taste. Sometimes he also takes a gallant resolve and, like the female,
begins to browse. You lucky creatures, who, so as not to lose a moment
of your four or five weeks' existence, yoke together the cravings of
love and hunger! Your motto is, "A short life and a merry one."
The Cerocoma, who is a golden green like the Cantharides, seems to
have partly adopted the amorous rites of her rival in dress. The male,
always the elegant sex in the insect tribe, wears special ornaments.
The horns or antennae, magnificently complicated, form as it were two
tufts of a thick head of hair. It is to this that the name Cerocoma
refers: the creature crested with its horns. When a bright sun shines
into the breeding-cage, it is not long before the insects form couples
on the bunch of everlastings. Hoisted on the female, whom he embraces
and holds with his two pairs of hind-legs, the male sways his head and
corselet up and down, all in a piece. This oscillatory movement has
not the fiery precipitation of that of the Cantharides; it is calmer
and as it were rhythmical. The abdomen moreover remains motionless and
seems unskilled in those slaps, as of a washerwoman's bat, which the
amorous denizen of the ash-tree so vigorously distributes with his
belly.
While the front half of the body swings up and down, the fore-legs
execute magnetic passes on either side of the tight-clasped female,
moving with a sort of twirl, so rapidly that the eye can hardly follow
them. The female appears insensible to this flagellatory twirl. She
innocently curls her antennae. The rejected suitor leaves her and
moves on to another. His dizzy, twirling passes, his protestations are
everywhere refused. The moment has not yet arrived, or rather the spot
is not propitious. Captivity appears to weigh upon the future mothers.
Before listening to their wooers they must have the open air, the
sudden joyful flight from cluster to cluster on the sunlit slope, all
gold with everlastings. Apart from the idyll of the twirling passes, a
mitigated form of the Cantharides' blows, the Cerocoma refused to
yield before my eyes to the last act of the bridal.
Among males the same oscillations of the body and the same lateral
flagellations are frequently practised. While the upper one makes a
tremendous to-do and whirls his legs, the one under him keeps quiet.
Sometimes a third scatterbrain comes on the scene, sometimes even a
fourth, and mounts upon the heap of his predecessors. The uppermost
bobs up and down and makes swift rowing-strokes with his fore-legs;
the others remain motionless. Thus are the sorrows of the rejected
beguiled for a moment.
The Zonites, a rude clan, grazing on the heads of the prickly eryngo,
despise all tender preliminaries. A few rapid vibrations of the
antennae on the males' part; and that is all. The declaration could
not be briefer. The pairing, with the creatures placed end to end,
lasts nearly an hour.
The Mylabres also must be very expeditious in their preliminaries, so
much so that my cages, which were kept well-stocked for two summers,
provided me with numerous batches of eggs without giving me a single
opportunity of catching the males in the least bit of a flirtation.
Let us therefore consider the egg-laying.
This takes place in August for our two species of Mylabres. In the
vegetable mould which does duty as a floor to the wire-gauze dome, the
mother digs a pit four-fifths of an inch deep and as wide as her body.
This is the place for the eggs. The laying lasts barely half an hour.
I have seen it last thirty-six hours with Sitares. This quickness of
the Mylabris points to an incomparably less numerous family. The
hiding-place is next closed. The mother sweeps up the rubbish with her
fore-legs, collects it with the rake of her mandibles and pushes it
back into the pit, into which she now descends to stamp upon the
powdery layer and cram it down with her hind-legs, which I see swiftly
working. When this layer is well packed, she starts raking together
fresh material to complete the filling of the hole, which is carefully
trampled stratum by stratum.
I take the mother from her pit while she is engaged in filling it up.
Delicately, with the tip of a camel-hair pencil, I move her a couple
of inches. The Beetle does not return to her batch of eggs, does not
even look for it. She climbs up the wire gauze and proceeds to graze
among her companions on the bindweed or scabious, without troubling
herself further about her eggs, whose hiding-place is only
half-filled. A second mother, whom I move only one inch, is no longer
able to return to her task, or rather does not think of doing so. I
take a third, after shifting her just as slightly, and, while the
forgetful creature is climbing up the trellis-work, bring her back to
the pit. I replace her with her head at the opening. The mother stands
motionless, looking thoroughly perplexed. She sways her head, passes
her front tarsi through her mandibles, then moves away and climbs to
the top of the dome without attempting anything. In each of these
three cases I have to finish filling in the pit myself. What then are
this maternity, which the touch of a brush causes to forget its
duties, and this memory, which is lost at a distance of an inch from
the spot? Compare with these shortcomings of the adult the expert
machinations of the primary larva, which knows where its victuals are
and as its first action introduces itself into the dwelling of the
host that is to feed it. How can time and experience be factors of
instinct? The newborn animalcule amazes us with its foresight; the
adult insect astonishes us with its stupidity.
With both Mylabres, the batch consists of some forty eggs, a very
small number compared with those of the Oil-beetle and the Sitaris.
This limited family was already foreseen, judging by the short space
of time which the egg-layer spends in her underground lodging. The
eggs of the Twelve-spotted Mylabris are white, cylindrical, rounded at
both ends and measure a millimetre and a half in length by half a
millimetre in width.[6] Those of the Four-spotted Mylabris are straw
coloured and of an elongated oval, a trifle fuller at one end than at
the other. Length, two millimetres; width, a little under one
millimetre.[7]
[Footnote 6: .058 x .019 inch.--_Translator's Note_.]
[Footnote 7: .078 x .039 inch.--_Translator's Note_.]
Of all the batches of eggs collected, one alone hatched. The rest were
probably sterile, a suspicion corroborated by the lack of pairing in
the breeding-cage. Laid at the end of July, the eggs of the
Twelve-spotted Mylabris began to hatch on the 5th of September. The
primary larva of this Meloid is still unknown, so far as I am aware;
and I shall describe it in detail. It will be the starting-point of a
chapter which perhaps will give us some fresh sidelights upon the
history of the hypermetamorphosis.
The larva is nearly 2 millimetres long.[8] Coming out of a good-sized
egg, it is endowed with greater vigour than the larvae of the Sitares
and Oil-beetles. The head is large, rounded, slightly wider than the
prothorax and of a rather brighter red. Mandibles powerful, sharp,
curved, with the ends crossing, of the same colour as the head, darker
at the tips. Eyes black, prominent, globular, very distinct. Antennae
fairly long, with three joints, the last thinner and pointed. Palpi
very much pronounced.
[Footnote 8: .078 inch.--_Translator's Note_.]
The first thoracic segment has very nearly the same diameter as the
head and is much longer than those which come after. It forms a sort
of cuirass equal in length to almost three abdominal segments. It is
squared off in front in a straight line and is rounded at the sides
and at the back. Its colour is bright red. The second ring is hardly a
third as long as the first. It is also red, but a little browner. The
third is dark brown, with a touch of green to it. This tint is
repeated throughout the abdomen, so that in the matter of colouring
the creature is divided into two sections: the front, which is a
fairly bright red, includes the head and the first two thoracic
segments; the second, which is a greenish brown, includes the third
thoracic segment and the nine abdominal rings.
The three pairs of legs are pale red, strong and long, considering the
creature's smallness. They end in a single long, sharp claw.
The abdomen has nine segments, all of an olive brown. The membranous
spaces which connect them are white, so that, from the second thoracic
ring downwards, the tiny creature is alternatively ringed with white
and olive brown. All the brown rings bristle with short, sparse hairs.
The anal segment, which is narrower than the rest, bears at the tip
two long cirri, very fine, slightly waved and almost as long as the
whole abdomen.
This description enables us to picture a sturdy little creature,
capable of biting lustily with its mandibles, exploring the country
with its big eyes and moving about with six strong harpoons as a
support. We no longer have to do with the puny louse of the
Oil-beetle, which lies in ambush on a cichoriaceous blossom in order
to slip into the fleece of a harvesting Bee; nor with the black atom
of the Sitaris, which swarms in a heap on the spot where it is
hatched, at the Anthophora's door. I see the young Mylabris striding
eagerly up and down the glass tube in which it was born.
What is it seeking? What does it want? I give it a Bee, a Halictus,[9]
to see if it will settle on the insect, as the Sitares and Oil-beetles
would not fail to do. My offer is scorned. It is not a winged
conveyance that my prisoners require.
[Footnote 9: Cf. _Bramble-bees and Others_: chaps. xii. to
xiv.--_Translator's Note_.]
The primary larva of the Mylabris therefore does not imitate those of
the Sitaris and the Oil-beetle; it does not settle in the fleece of
its host to get itself carried to the cell crammed with victuals. The
task of seeking and finding the heap of food falls upon its own
shoulders. The small number of the eggs that constitute a batch also
leads to the same conclusion. Remember that the primary larva of the
Oil-beetle, for instance, settles on any insect that happens to pay a
momentary visit to the flower in which the tiny creature is on the
look-out. Whether this visitor be hairy or smooth-skinned, a
manufacturer of honey, a canner of animal flesh or without any
determined calling, whether she be Spider, Butterfly, Fly or Beetle
makes no difference: the instant the little yellow louse espies the
new arrival, it perches on her back and leaves with her. And now it
all depends on luck! How many of these stray travellers must be lost;
how many will never be carried into a warehouse full of honey, their
sole food! Therefore, to remedy this enormous waste, the mother
produces an innumerable family. The Oil-beetle's batch of eggs is
prodigious. Prodigious too is that of the Sitaris, who is exposed to
similar misadventures.
If, with her thirty or forty eggs, the Mylabris had to run the same
risks, perhaps not one larva would reach the desired goal. For so
strictly limited a family a safer method is needed. The young larva
must not get itself carried to the game-basket, or more probably to
the honey-pot, at the risk of never reaching it; it must travel on its
own legs. Allowing myself to be guided by the logic of things, I shall
therefore complete the story of the Twelve-spotted Mylabris as
follows.
The mother lays her eggs underground near the spots frequented by the
foster-mothers. The recently-hatched young grubs leave their lodgings
in September and travel within a restricted radius in search of
burrows containing food. The little creature's sturdy legs allow of
these underground investigations. The mandibles, which are just as
strong, necessarily play their part. The parasite, on forcing its way
into the food-pit, finds itself faced with either the egg or the young
larva of the Bee. These are competitors, whom it is important to get
rid of as quickly as possible. The hooks of the mandibles now come
into play, tearing the egg or the defenceless grub. After this act of
brigandage, which may be compared with that of the primary larva of
the Sitaris ripping open and drinking the contents of the Anthophora's
egg, the Meloid, now the sole possessor of the victuals, doffs its
battle array and becomes the pot-bellied grub, the consumer of the
property so brutally acquired. These are merely suspicions on my part,
nothing more. Direct observation will, I believe, confirm them, so
close is their connection with the known facts.
Two Zonites, both visitors of the eryngo-heads during the heats of
summer, are among the Meloidae of my part of the country. They are
_Zonitis mutica_ and _Z. praeusta_. I have spoken of the first in
another volume;[10] I have mentioned its pseudochrysalis found in the
cells of two Osmiae, namely, the Three-pronged Osmia, which piles its
cells in a dry bramble-stem, and the Three-horned Osmia and also
Latreille's Osmia, both of which exploit the nests of the Chalicodoma
of the Sheds. The second Zonitis is to-day adding its quota of
evidence to a story which is still very incomplete. I have obtained
the Burnt Zonitis, in the first place, from the cotton pouches of
_Anthidium scapulare_, who, like the Three-toothed Osmia, makes her
nests in the brambles; in the second place, from the wallets of
_Megachile sericans_, made with little round disks of the leaves of
the common acacia; in the third place, from the cells which _Anthidium
bellicosum_[11] builds with partitions of resin in the shell of a dead
Snail. This last Anthidium is the victim also of the Unarmed Zonitis.
Thus we have two closely-related exploiters for the same victim.
[Footnote 10: Cf. _Bramble-bees and Others_: chaps. i., iii. and
x.--_Translator's Note_.]
[Footnote 11: For the Cotton-bee, Leaf-cutter and Resin-bee mentioned,
cf. _Bramble-bees and Others_: _passim_.--_Translator's Note_.]
During the last fortnight of July, I witness the emergence of the
Burnt Zonitis from the pseudochrysalis. The latter is cylindrical,
slightly curved and rounded at both ends. It is closely wrapped in the
cast skin of the secondary larva, a skin consisting of a diaphanous
bag, without any outlet, with running along each side a white tracheal
thread which connects the various stigmatic apertures. I easily
recognize the seven abdominal stigmata; they are round and diminish
slightly in width from front to back. I also detect the thoracic
stigma. Lastly, I perceive the legs, which are quite small, with weak
claws, incapable of supporting the creature. Of the mouth-parts I see
plainly only the mandibles, which are short, weak and brown. In short,
the secondary larva was soft, white, big-bellied, blind, with
rudimentary legs. Similar results were furnished by the shed skin of
the secondary larva of _Zonitis mutica_, consisting, like the other,
of a bag without an opening, fitting closely over the pseudochrysalis.
Let us continue our examination of the relics of the Burnt Zonitis.
The pseudochrysalis is red, the colour of a cough-lozenge. It remains
intact after opening, except in front, where the adult insect has
emerged. In shape it is a cylindrical bag, with firm, elastic walls.
The segmentation is plainly visible. The magnifying-glass shows the
fine star-shaped dots already observed in the Unarmed Zonitis. The
stigmatic apertures have a projecting, dark-red rim. They are all,
even the last, clearly marked. The signs of the legs are mere studs,
hardly protruding, a little darker than the rest of the skin. The
cephalic mask is reduced to a few mouldings which are not easy to
distinguish.
At the bottom of this pseudochrysalidal sheath I find a little white
wad which, when placed in water, softened and then patiently
unravelled with the tip of a paint-brush, yields a white, powdery
substance, which is uric acid, the usual product of the work of the
nymphosis, and a rumpled membrane, in which I recognize the cast skin
of the nymph. There should still be the tertiary larva, of which I see
not a trace. But, on taking a needle and gradually breaking the
envelope of the pseudochrysalis, after soaking it awhile in water, I
see it dividing into two layers, one an outer layer, brittle, horny in
appearance and currant-red; the other an inner layer, consisting of a
transparent, flexible pellicle. There can be no doubt that this inner
layer represents the tertiary larva, whose skin is left adhering to
the envelope of the pseudochrysalis. It is fairly thick and tough, but
I cannot detach it except in shreds, so closely does it adhere to the
horny, crumbly sheath.
Since I possessed a fair number of pseudochrysalids, I sacrificed a
few in order to ascertain their contents on the approach of the final
transformations. Well, I never found anything that I could detach; I
never succeeded in extracting a larva in its tertiary form, though
this larva is so easily obtained from the amber pouches of the Sitares
and, in the Oil-beetles and Cerocomae, emerges of its own accord from
the split wrapper of the pseudochrysalis. When, for the first time,
the stiff shell encloses a body which does not adhere to the rest,
this body is a nymph and nothing else. The wall surrounding it is a
dull white inside. I attribute this colouring to the cast skin of the
tertiary larva, which was inseparably fixed to the shell of the
pseudochrysalis.
The Zonites, therefore, display a peculiarity which is not offered by
the other Meloidae, namely, a series of tightly-fitting shells, one
within the other. The pseudochrysalis is enclosed in the skin of the
secondary larva, a skin which forms a pouch without an orifice, fitted
very closely to its contents. The slough of the tertiary larva fits
even more closely to the inner surface of the pseudochrysalid sheath.
The nymph alone does not adhere to its envelope. In the Cerocomae and
the Oil-beetles, each form of the hypermetamorphosis becomes detached
from the preceding skin by a complete extraction; the contents are
removed from the ruptured container and have no further connection
with it. In the Sitares, the successive casts are not ruptured and
remain enclosed inside one another, but with an interval between, so
that the tertiary larva can move and turn as it wishes in its multiple
enclosure. In the Zonites, there is the same arrangement, with this
difference, that, until the nymph appears, there is no empty space
between one slough and the next. The tertiary larva cannot budge. It
is not free, as witness its cast skin, which fits so precisely to the
envelope of the pseudochrysalis. This form would therefore pass
unperceived if its existence were not proclaimed by the membrane which
lines the inside of the pseudochrysalid pouch.
To complete the story of the Zonites, the primary larva is lacking. I
do not yet know it, for, when rearing the insect under wire-gauze
covers, I never succeeded in obtaining a batch of eggs.