THE TWO-BANDED SCOLIA
If strength were to take precedence of other zoological attributes, the
Scoliæ would reign in the first rank, in the order of the Hymenoptera.
Some of them can be compared in size with the little orange-crested
northern Wren, the Kinglet, who comes down to us, to visit the maggoty
buds, at the time of the first autumnal mists. The largest, the most
imposing of our sting-carriers, the Humble-bee, the Hornet, cut a poor
figure beside certain Scoliæ. Among this group of giants, my region
boasts the Common or Garden Scolia (Scolia Hortorum, van der Lind), who
exceeds four centimetres [29] in length and measures ten [30] from tip
to tip of her outstretched wings, and the Hemorrhoidal Scolia (Scolia
Hemorrhoïdalis, van der Lind), who vies in dimensions with the Garden
Scolia and is distinguished from her, in the main, by the brush of red
bristles at the tip of her belly.
A black livery, with broad yellow patches; tough wings amber as an
onion-skin and shot with purple reflections; coarse, knotted legs,
bristling with rugged hairs; a massive build; a powerful head, helmeted
with a hard skull; a stiff and clumsy gait; a short, silent flight,
devoid of soaring qualities: this, in few words, describes the
appearance of the female, powerfully equipped for her severe task. That
love-lorn idler, the male, is more gracefully horned, more daintily
clad, more elegantly shaped, without altogether losing the character of
sturdiness which is the predominant feature in his mate.
It is not without qualms that the insect-collector finds himself for
the first time in the presence of the Garden Scolia. How is he to
capture the commanding brute, how to protect himself against its sting?
If the effect of the sting be in proportion to the Hymenopteron’s size,
then a prick from the Scolia is something to be dreaded. The Hornet,
once he lugs out, hurts us atrociously. What, then, would it be like if
one were stabbed by this colossus? The prospect of a swelling the size
of your fist and as painful as though it were blistered by a red-hot
iron passes through your mind, just as you are about to cast the net.
And you refrain, you beat a retreat, only too glad not to have aroused
the attention of the dangerous animal.
Yes, I confess to having quailed before my first Scoliæ, eager though I
was to enrich my incipient collection with this glorious insect.
Smarting recollections left behind by the Wasp and the Hornet had
something to say to this excessive prudence. I say excessive, for
to-day, taught by long experience, I have got the better of my former
fears and, if I see a Scolia resting on a thistle-head, I have no
scruples about taking her in the tips of my fingers, with no precaution
of any kind, threatening though her aspect be. My pluck is only
apparent, as I am pleased to inform the novice at Hymenopteron-hunting.
The Scoliæ are very peaceful. Their sting is an implement of work much
rather than a weapon of war: they use it to paralyze the prey intended
for their family; and only in the last extremity do they employ it in
their own defence. Moreover, the lack of suppleness in their movements
enables one nearly always to avoid the sting; and, lastly, if one were
stung, the pain of the prick is almost insignificant. This absence of a
bitter smart in the poison is a pretty constant fact among the
game-hunting Hymenoptera, whose weapon is a surgical lancet intended
for the most delicate physiological operations.
Among the other Scoliæ of my district, I will mention the middle-sized
Two-banded Scolia (Scolia Bifasciata, van der Lind), whom I see yearly,
in September, exploiting the manure-heaps of dead leaves arranged, for
her benefit, in a corner of my yard. Let us watch her performance
comfortably indoors.
After the Cerceris, it is well to study others, hunting an unarmed
prey, a prey vulnerable at all points save the skull, but giving only a
single prick with the sting. Of these two conditions, the Scoliæ
fulfilled one, with their regulation game, the soft grub of Cetonia,
Oryctes or Anoxia, according to their species. Did they fulfil the
second? I was convinced beforehand, judging from the anatomy of the
victims, with its concentrated nervous system, that the sting was
unsheathed but once; I even foresaw the point in which the weapon must
be thrust.
These were statements dictated by the anatomist’s scalpel, without the
least direct proof from observed facts. Stratagems accomplished
underground escaped the eye and seemed to me bound always to escape it.
How, indeed, could one hope that an animal whose art is practised in
the darkness of a manure-heap should be persuaded to work in the full
light of day? I did not reckon on it in the least. Nevertheless, for
conscience’ sake, I tried putting the Scolia in touch with her quarry
under glass. And it was well that I did so, for my success was in the
inverse ratio to my expectations. Never did beast of prey show greater
zeal in attacking under artificial conditions. Every insect
experimented upon rewarded me, sooner or later, for my patience. Let us
watch Scolia Bifasciata at work, operating on her Cetonia grub.
The captive grub tries to escape its terrible neighbour. Turned over on
its back according to its custom, it shuffles along eagerly, going
round and round the glass arena. Soon, the Scolia’s attention is
aroused and is evinced by continual little taps of the tips of its
antennæ upon the table, which now represents the customary soil. The
Hymenopteron falls upon her prey and attacks the monstrous meal by the
hinder end. She climbs upon the Cetonia, using the abdominal extremity
as a lever. The assaulted grub does nothing but scud all the faster on
its back, without rolling itself into a defensive posture. The Scolia
reaches the front part, after falls and accidents that vary greatly,
according to the degree of tolerance of the grub, her temporary mount.
With her mandibles, she nips a point on the upper surface of the
thorax; she places herself across the grub, curves herself into an arch
and tries to touch with the point of her belly the region where the
sting is to be darted. The arch is a little too short to embrace almost
the whole circuit of the corpulent prey, for which reason the efforts
and attempts are made over and over again, at great length. The tip of
the abdomen makes untold exertions, applies itself here, there and
elsewhere and, as yet, stops nowhere. This tenacious searching in
itself proves the importance which the paralyzer attaches to the spot
at which its bistoury is to enter.
Meanwhile, the grub continues to move along on its back. Suddenly, it
buckles and, with a jerk of the head, flings the enemy to a distance.
Undaunted by all her failures, the Hymenopteron stands up, brushes her
wings and recommences the assault of the colossus, almost always by
clambering on the grub by the rear extremity. At last, after any number
of fruitless attempts, the Scolia succeeds in attaining the proper
position. She lies across the grub; her mandibles hold a point of the
thorax on the dorsal face tight-gripped; her body, curved into an arch,
passes under the grub and reaches the neighbourhood of the neck with
the tip of the belly. Placed in grave danger, the Cetonia twists,
buckles, unbuckles, turns and writhes. The Scolia does not interfere.
Holding her victim in a close embrace, she turns with it, allows
herself to be dragged above, below, aside, at the mercy of the
contortions. So fierce is her determination that I am now able to
remove the glass bell and watch the details of the drama in the open.
Soon, notwithstanding the tumult, the tip of the Scolia’s belly feels
that the suitable point is found. Then and not till then is the dart
unsheathed. It is driven home. The thing is done. The grub, but now
active and swollen, suddenly becomes inert and limp. It is paralyzed.
Henceforth, all movement ceases, save in the antennæ and mouth-pieces,
which will continue for a long time to declare a remnant of life.
The place of the wound has never varied in the series of struggles
under the glass bell: it occupies the middle of the dividing line
between the prothorax and the mesothorax, on the ventral surface. Let
us observe that the Cerceris, who operates upon Weevils, which insects
have a concentrated nervous chain like that of the Cetonia grub,
inserts her sting at the same point. The similarity of the nervous
organization occasions a similarity of method. Let us observe also that
the sting of the Scolia remains for some time in the wound and rummages
with a pronounced persistency. To judge by the movements of the tip of
the abdomen, one would say that the weapon is exploring and selecting.
Free to turn about as it pleases within narrow limits, the sting’s
point is probably searching for the little bundle of nerves which it
must prick, or at least sprinkle with poison, in order to obtain a
withering paralysis.
I will not end my report of the duel without relating a few more facts,
of minor importance. The Two-banded Scolia is an ardent persecutor of
the Cetonia. At one sitting, the same mother stabs three grubs, one
after the other, before my eyes. She refuses the fourth, perhaps
through fatigue, or because her poison-phial is exhausted. Her refusal
is but temporary. The next day, she begins anew and paralyzes two
worms; the following day again, but with a zeal that diminishes from
day to day.
The other predatory insects that go on long hunting-expeditions embrace
the prey which they have rendered lifeless, drag it, convey it, each in
its own fashion, and, laden with their burden, long try to escape from
the bell and to reach the burrow. Disheartened by vain attempts, they
abandon it at last. The Scolia does not move her prey, which lies
indefinitely on its back at the spot of sacrifice. After drawing her
dagger from the wound, she leaves her victim alone and starts
fluttering against the walls of the bell, without troubling about it
further. Things must happen in the same way in the manure-heap, under
normal conditions. The paralyzed morsel is not carried elsewhither, to
a special cellar: where the struggle occurred, there it receives, on
its spread belly, the egg whence the consumer of the succulent dainty
will presently emerge. This saves the expense of a house. It goes
without saying that the Scolia does not lay under glass: the mother is
too prudent to expose her egg to the dangers of the open air.
A second detail strikes me: the fierce persistency of the Scolia. I
have seen the fight prolonged for a good quarter of an hour, with
frequent alternations of successes and reverses, before the
Hymenopteron achieved the requisite position and reached with the tip
of her belly the point at which the sting must enter. During her
assaults, which are resumed as soon as repelled, the aggressor
repeatedly applies the extremity of her abdomen against the grub, but
without unsheathing; for I should perceive this by the start of the
animal injured by the prick. The Scolia, therefore, does not sting the
Cetonia anywhere until the desired point offers beneath the weapon. The
fact that no wounds are made elsewhere is not in any way due to the
structure of the grub, which is soft and penetrable at all points,
except the skull. The spot sought by the sting is no less
well-protected than the others by the dermal wrapper.
In the struggle, the Scolia, curved archwise, is sometimes caught in
the vice of the Cetonia, which forcibly contracts and buckles itself.
Heedless of the rough embrace, the Hymenopteron does not let go with
either her teeth or her ventral tip. Then follows a confused scuffle
between the two locked insects, of which first one and next the other
is on the top. When the grub succeeds in ridding itself of its enemy,
it unrolls itself afresh, stretches itself at full length and proceeds
to paddle along on its back with all possible speed. Its defensive
artifices amount to no more than this. At an earlier period, when I had
not yet seen for myself and was obliged to take probability for my
guide, I was willing to grant it the trick of the hedgehog, who rolls
himself into a ball and defies the dog. I thought that, doubled up,
with a force which my fingers had some difficulty in overcoming, it
would in like manner defy the Scolia, who was powerless to unroll it
and disdainful of any point but that of her choice. I wished the grub
to possess and I believed that it did possess this very simple and
efficacious means of defence. But I had too great confidence in its
ingenuity. Instead of copying the hedgehog and remaining contracted, it
flees with its belly in the air; foolishly, it adopts the very posture
which allows the Scolia to make the assault and to reach the point at
which the fatal blow is struck.
Let us pass on to others. I have just captured an Interrupted Scolia
(Colpa Interrupta, Latr.), exploring the sands, no doubt in quest of
game. It is important to make use of her as soon as may be, before her
ardour has been cooled by the tedium of captivity. I know her prey, the
grub of Anoxia Australis; I know, from my old habits of digging, the
spots beloved by the worm: the sand-dunes heaped by the wind at the
foot of the rosemary-shrubs on the slopes of the neighbouring hills. It
will be hard work finding it, for nothing is rarer than a common thing,
when it is needed in a hurry. I call in the aid of my father, an old
man of ninety, but still straight as a wand. Shouldering a shovel and a
three-pronged luchet, we set out under a sun in which you could cook an
egg. Exerting our feeble powers in turns, we cut a trench in the sand
where I hope to find the Anoxia. My hopes are not disappointed. In the
sweat of my brow—never was truer word spoken—after shifting and sifting
through my fingers at least two cubic yards of sandy soil, I am the
fortunate possessor of two grubs. Had I not wanted them, I should have
dug them up by the handful! However, my lean and costly harvest is
sufficient for the moment. To-morrow, I shall send stronger arms to
continue the digging.
And now let us repay ourselves for our trouble by witnessing the drama
under glass. Heavy and clumsy in her ways, the Scolia moves slowly
round the arena. At the sight of the game, her attention wakes up. The
fight is heralded by the same preparations as those displayed by the
Two-banded Scolia: the Hymenopteron polishes her wings and taps the
table with the tips of her antennæ. And now, up, lads, and at ’em! The
attack begins. Unfit to move over a flat surface, because of its short,
weak legs; lacking, moreover, the Cetonia’s eccentric means of
locomotion on its back, the big-bellied worm does not dream of running
away: it rolls itself up. The Scolia, with her powerful nippers, grabs
its skin, now at once place, now at another. Buckled into an arch whose
two ends almost meet, she strives to thrust the tip of her belly into
the narrow opening of the volute formed by the grub. The fight is
conducted quite calmly, without hard blows and with varying fortunes.
It represents the obstinate attempt of a live split ring trying to slip
one of its ends into another live split ring, which displays an equal
obstinacy in remaining closed. The Scolia holds the game in subjection
with her legs and mandibles; she makes her attempt first on one side
and then on the other, without succeeding in unrolling the torus, which
becomes the more contracted the more it feels itself in danger. The
actual circumstances make the operation difficult: the prey slips and
rolls over the table, when the insect goes for it too briskly; points
of support are wanting and the sting cannot reach the desired spot; for
over an hour, one vain attempt follows upon the other, divided by
spells of rest, during which the two adversaries look like two narrow
rings wound one inside the other.
What ought the sturdy Cetonia grub to do in order to defy the
Two-banded Scolia, who is nothing like so strong as her victim? Imitate
the Anoxia, of course, and remain rolled up like a hedgehog until the
enemy retreats. It tries to flee, unrolls itself and thus causes its
own undoing. The other does not budge from its defensive posture and
resists successfully. Is this due to acquired prudence? No, but to the
impossibility of acting otherwise on the polished surface of a table.
Heavy, obese, weak-legged, bent into a hook after the manner of the
common white maggot, the Anoxia grub is unable to shift its position on
a smooth surface; it flounders painfully, lying on its side. What it
wants is the shifting soil wherein, using its mandibles as a spade, it
digs and buries itself.
Let us try if sand will shorten the battle, of which the end does not
yet seem in sight after an hour’s waiting. I lightly sprinkle the
arena. The attack is resumed more fiercely than ever. The grub, feeling
the sand, its natural dwelling-place, now also tries to slip away, the
reckless one! What did I tell you? Its torus does not represent
acquired prudence, but the necessity of the moment. The harsh
experience of past misfortunes has not yet taught it the precious
advantage which it would derive from its volute kept closed as long as
danger lasts. Besides, not all are equally cautious on the firm support
of my table. The biggest even seem ignorant of what they understood so
well in their youth: the art of self-defence by rolling one’s self in a
ball.
I take up my story again with a fine-sized quarry, less liable to slip
under the Scolia’s pushes. The grub, when assailed, does not curl up,
does not contract into a ring, like its predecessor, which was younger
and but half its size. It tosses about clumsily, lying on its side,
half-opened. Its only attempt at defence is to wriggle; it opens,
closes and reopens its big mandibular hooks. The Scolia grabs it at
random, winds her rough, hairy legs around it and, for nearly fifteen
minutes, strives her hardest atop of the rich dainty.
At last, after a series of not very riotous affrays, the favourable
position is gained, the propitious moment arrives and the sting is
planted in the grub’s thorax, at a central spot, under the neck and
level with the fore-legs. The effect is instantaneous: total inertia,
save in the appendages of the head, the antennæ and mouth-pieces. I
find the same results, the same prick at a precise, invariable spot,
among my different operators, captured from time to time with a
successful stroke of the net.
Let us say, in conclusion, that the attack delivered by the Interrupted
Scolia is much less fiery than that of her two-banded sister. This
rough, sand-digging Hymenopteron has a clumsy gait and stiff, almost
automatic movements. She does not easily repeat her dagger-thrust. Most
of those with whom I experimented refused a second victim on the day
after their exploits and on the following day. Half-asleep, they grew
excited only when stimulated through my teasing them with a straw. Nor
does the Two-banded Scolia, that more agile, more enthusiastic
huntress, invariably unsheath when invited so to do. All those Nimrods
are liable to moments of inaction which the presence of a new prey will
not succeed in disturbing.
The Scoliæ have taught me no more than I have said, for lack of
subjects belonging to other species. No matter: the results obtained
constitute, to my mind, no small triumph. After seeing the Scoliæ at
work, I said to myself, guided merely by the anatomical structure of
the victims, that the grubs of Cetonia, of Anoxia, of Oryctes must be
paralyzed with a single prick of the sting; I even specified the point
at which the dagger had to strike, a central point in the immediate
neighbourhood of the fore-legs. Of the three kinds of sacrificers, two
allowed me to be present at their surgical operation, which the third,
I am certain, will not contradict. In both cases, a single blow of the
lancet; in both cases, an inoculation with the poison at the place
settled in advance. No calculator in an observatory could show greater
accuracy in foretelling the position of his planet. An idea may be
considered proved when it attains this mathematical anticipation of the
future, this positive knowledge of the unknown. When will the extollers
of chance achieve a like success? Order calls for order; and chance has
no rule.
THE RINGED CALICURGUS