THE BEAR LARINUS
I sally forth in the night, with a lantern, to spy out the land. Around
me, a circle of faint light enables me to recognize the broad masses
fairly well, but leaves the fine details unperceived. At a few paces’
distance, the modest illumination disperses, dies away. Farther off
still, everything is pitch-dark. The lantern shows me—and but very
indistinctly—just one of the innumerable pieces that compose the mosaic
of the ground.
To see some more of them, I move on. Each time there is the same narrow
circle, of doubtful visibility. By what laws are these points,
inspected one by one, correlated in the general picture? The candle-end
cannot tell me; I should need the light of the sun.
Science too proceeds by lantern-flashes; it explores nature’s
inexhaustible mosaic piece by piece. Too often the wick lacks oil; the
glass panes of the lantern may not be clean. No matter: his work is not
in vain who first recognizes and shows to others one speck of the vast
unknown.
However far our ray of light may penetrate, the illuminated circle is
checked on every side by the barrier of the darkness. Hemmed in by the
unfathomable depths of the unknown, let us be satisfied if it be
vouchsafed to us to enlarge by a span the narrow domain of the known.
Seekers, all of us, tormented by the desire for knowledge, let us move
our lantern from point to point: with the particles explored we shall
perhaps be able to piece together a fragment of the picture.
To-day the shifting of the lantern’s rays leads us to the Bear Larinus
(L. ursus, Fabr.), the exploiter of the carline thistles. We must not
let this inappropriate name of Bear give us an unfavourable notion of
the insect. It is due to the whim of a nomenclator who, having
exhausted his vocabulary, baffled by the never-ending stream of things
already named, uses the first word that comes to hand.
Others, more happily inspired, perceiving a vague resemblance between
the sacerdotal ornament, the stole, and the white bands that run down
the Weevil’s back, have proposed the name of Stoled Larinus (L.
stolatus, Gmel.). This term would please me; it gives a very good
picture of the insect. The Bear, making nonsense, has prevailed. So be
it: non nobis tantas componere lites.
The domain of this Weevil is the corymbed carlina (C. corymbosa, Lin.),
a slender thistle, not devoid of elegance, harsh-looking though it be.
Its heads, with their tough, yellow-varnished spokes, expand into a
fleshy mass, a genuine heart, like an artichoke’s, which is defended by
a hedge of savage folioles broadly welded at the base. It is at the
centre of this palatable heart that the larva is established, always
singly.
Each has its exclusive demesne, its inviolable ration. When an egg, a
single egg, has been entrusted to the mass of florets, the mother moves
on, to continue elsewhere; and, should some newcomer by mistake take
possession of it, her grub, arriving too late and finding the place
occupied, will die.
This isolation tells us how the larva feeds. The carlina’s foster-child
cannot live on a clear broth, as does the echinops’; for, if the drops
trickling from a wound were sufficient, there would be victuals for
several here. The blue thistle feeds three or four boarders without any
loss of solid material beyond that resulting from a slight gash. Given
such coy-toothed feeders, the heart of the carline thistle would
support quite as many.
It is always, on the contrary, the portion of one alone. Thus we
already guess that the grub of the Bear Larinus does not confine itself
to lapping up discharges of sap and that it likewise feeds upon its
artichoke-heart, the standing dish.
The adult also feeds upon it. On the cone covered with imbricated
folioles it makes spacious excavations in which the sweet milk of the
plant hardens into white beads. But these broken victuals, these cut
cakes off which the Weevil has made her meal, are disdained when the
egg-laying comes into question, in June and July. A choice is then made
of untouched heads, not as yet developed, not yet expanded and still
contracted into prickly globules. The interior will be tenderer than
after they are full-blown.
The method is the same as that of the Spotted Larinus. With her rostral
gimlet the mother bores a hole through the scales, on a level with the
base of the florets; then, with the aid of her guiding probe, she
installs her opalescent white egg at the bottom of the shaft. A week
later the grub makes its appearance.
Some time in August let us open the thistle-heads. Their contents are
very diverse. There are larvæ here of all ages; nymphs covered with
reddish ridges, above all on the last segments, twitching violently and
spinning round when disturbed; lastly, perfect insects, not yet adorned
with their stoles and other ornaments of the final costume. We have
before our eyes the means of following the whole development of the
Weevil at the same time.
The folioles of the blossom, those stout halberds, are welded together
at their base and enclose within their rampart a fleshy mass, with a
flat upper surface and cone-shaped underneath. This is the larder of
the Bear Larinus.
From the bottom of its cell the new-born grub dives forthwith into this
fleshy mass. It cuts into it deep. Unreservedly, respecting only the
walls, it digs itself, in a couple of weeks, a recess shaped like a
sugar-loaf and prolonged until it touches the stalk. The canopy of this
recess is a dome of florets and hairs forced upwards and held in place
by an adhesive. The artichoke-heart is completely emptied; nothing is
respected save the scaly walls.
As its isolation led us to expect, the grub of the Bear Larinus
therefore eats solid food. There is, however, nothing to prevent it
from adding to this diet the milky exudations of the sap.
This fare, in which solid matter predominates, necessarily involves
solid excreta, which are unknown in the inmate of the blue thistle.
What does the hermit of the carline thistle do with them, cooped up in
a narrow cell from which nothing can be shot outside? It employs them
as the other does its viscous drops; it upholsters its cell with them.
I see it curved into a circle with its mouth applied to the opposite
orifice, carefully collecting the granules as these are evacuated by
the intestinal factory. It is precious stuff, this, very precious; and
the grub will be careful not to lose a scrap of it, for it has naught
else wherewith to plaster its dwelling.
The dropping seized is therefore placed in position at once, spread
with the tips of the mandibles and compressed with the forehead and
rump. A few waste chips and flakes, a few bits of down are torn from
the uncemented ceiling overhead; and the plasterer incorporates them,
atom by atom, with the still moist putty.
This gives, as the inmate increases in size, a coat of rough-cast
which, smoothed with meticulous care, lines the whole of the cell.
Together with the natural wall furnished by the prickly rind of the
artichoke, it makes a powerful bastion, far superior, as a defensive
system, to the thatched huts of the Spotted Larinus.
The plant, moreover, lends itself to protracted residence. It is
slightly built but slow to decay. The winds do not prostrate it in the
mire, supported as it is by brushwood and sturdy grasses, its habitual
environment. When the handsome thistle with the blue spheres has long
been mouldering on the edge of the roads, the carlina, with its
rot-proof base, still stands erect, dead and brown but not dilapidated.
Another excellent quality is this: the scales of its heads contract and
make a roof which the rain has difficulty in penetrating.
In such a shelter there is no occasion to fear the dangers which make
the Spotted Larinus quit her pitchers at the approach of winter: the
dwelling is securely founded and the cell is dry. The Bear Larinus is
well aware of these advantages; she is careful not to imitate the other
in wintering under the cover of dead leaves and stone-heaps. She does
not stir abroad, assured beforehand of the efficiency of her roof.
On the roughest days of the year, in January, if the weather permits me
to go out, I open the heads of the carline thistles which I come
across. I always find the Larinus there, in all the freshness of her
striped costume. She is waiting, benumbed, until the warmth and
animation of May return. Then only will she break the dome of her cabin
and go to take part in the festival of spring.
In majesty of bearing and magnificence of blossom our kitchen-gardens
have nothing superior to the cardoon and its near relative the
artichoke. Their heads grow to double the size of a man’s fist. Outside
are spiral series of imbricated scales which, without being aggressive,
diverge at maturity in the shape of broad, stiff, pointed blades.
Beneath this armament is a fleshy, hemispherical swelling, as big as
half an orange.
From this rises a serried mass of long white hairs, a sort of fur, than
which a Polar Bear’s is no thicker. Closely surrounded by this hair,
the seeds are crowned with feathers which double the thickness of the
shaggy chevaux de frise. Above this, delighting the eye, blooms the
spreading tuft of flowers, coloured a splendid lapis lazuli, like that
of the cornflower, the joy of the harvest.
This is the chief domain of a third Larinus (L. scolymi, Oliv.), a big
Weevil, thickset, broad-backed, powdered with yellow ochre. The
cardoon, which provides our table with the fleshy veins of its leaves,
but whose heads are disdained, is the insect’s customary home; but,
should the gardener leave the artichoke a few late heads, these are
accepted by the Larinus as eagerly as the cardoon’s. Under different
names, the two plants are merely horticultural varieties; and the
Weevil, a thorough expert, makes no mistake about it.
Under the scorching July sun, a cardoon-head exploited by the Larini is
a sight worth seeing. Drunk with heat, busily staggering amid the
thicket of blue florets, they dive with their tails in the air, sinking
and even disappearing into the depths of the shaggy forest.
What do they do down there? It is not possible to observe them
directly; but a local inspection after the work is finished will tell
us. Between the tufts of hairs, not far from the base, they clear with
the rostrum a place to receive their egg. If they are able to reach a
seed, they rid it of its feathers and cut a shallow cup in it, an
egg-cup as it were. The probe is pushed no farther. The fleshy dome,
the tasty heart which one would at first suppose to be the favourite
morsel, is never attacked by the pregnant mothers.
As might have been expected, so rich an establishment implies a
numerous population. If the head is a good-sized one, it is not unusual
to find a score or more of table-companions, plump, red-headed grubs,
with fat, glossy backs. There is plenty of room for all.
For the rest, they are of a very stay-at-home habit. Far from straying
at random over the abundant food-supply, in which they might well
sample the best and pick their mouthfuls, they remain encamped within
the narrow area of the place where they were hatched. Moreover, despite
their corpulence, they are extremely frugal, to such a point that,
excepting the inhabited patches, the floral head retains its full
vigour and ripens its seeds as usual.
In this blazing summer weather, three or four days are enough for the
hatching. If the young grub is at some distance from the seeds, it
reaches them by slipping along the hairs, a few of which it gathers on
its way. If it is born in contact with a seed, it remains in its native
cup, for the desired point is attained.
Its food consists, in fact, of the few surrounding seeds, five or six,
hardly more; and even so the greater number are only in part consumed.
True, when it has grown stronger, the larva bites deeper and digs in
the fleshy receptacle a little pit that will serve as the foundation of
its future cell. The waste products of nutrition are pushed backwards,
where they set in a hard lump, held in position by the palisade of the
hairs.
A modest scale of diet, when all is said: half a dozen unripe seeds and
a few mouthfuls taken from the cake consisting of the receptacle. These
peaceful creatures must derive singular benefit from their food to
acquire such plumpness so cheaply. An undisturbed and temperate diet is
better than an uneasy feast.
Two or three weeks devoted to these pleasures of the table and our grub
has become a fat baby. Then the blissful consumer becomes a craftsman.
The placid gratification of the belly is followed by the worries of the
future. We have to build ourselves a castle in which to effect the
metamorphosis.
From all around it the grub collects hairs, which it chops into
fragments of different lengths. It places them in position with the tip
of its mandibles, butts them with its head and presses them by rolling
them with its rump. Without further manipulation this would remain a
crazy protection, constantly collapsing and forcing the recluse to make
continual repairs. But the builder is thoroughly acquainted with the
eccentric ways of its fellow-craftsmen on the echinops; it possesses a
cement-factory in the end of its intestine.
If I rear it in a glass tube with a piece of its native artichoke, I
see it from time to time curving itself into a ring and gathering with
its teeth a drop of a whitish, sticky substance which the hinder part
of the grub sparingly provides. The glue is instantly spread hither and
thither, swiftly, for it sets quickly. Thus the hairy particles are
bound together and what was flimsy felt becomes a solid fabric.
When completed, the work is a sort of turret, the base of which is
contained in the little pit of the receptacle, from which the grub
obtained part of its nourishment. The dense mane of untouched hairs
forms a rampart above and at the sides. It is a somewhat clumsy edifice
without, shored up by the adjacent fur; but it is nicely smoothed
within and coated in every part with the intestinal glue, which becomes
a lustrous reddish material, like a shellac varnish. The castle-keep
measures one and a half centimetres in height. [30]
Towards the end of August most of the recluses are in the perfect
state. Many have even burst the vaulted ceiling of their home; rostrum
in air, they investigate the weather, awaiting the hour of departure.
The cardoon-head by this time is quite dry upon its withered stalk. Let
us strip it of its scales and, with a pair of scissors, clip its fur as
closely as possible.
The result thus obtained is truly curious. It is a sort of convex
brush, pierced here and there with deep cavities wide enough to admit
an ordinary lead-pencil. The sides consist of a reddish-brown wall
covered with incrustations of hairy débris. Each of these cavities is
the cell of an adult Larinus. At first sight one would take the thing
for the comb of some extraordinary Wasps’-nest.
Let us mention a fourth member of the same group. This is the Spangled
Larinus (L. conspersus, Sch.), smaller in size than the three foregoing
species and more simply clad. She is sprinkled with small yellow-ochre
spots on a black ground.
Her most sumptuous establishment, as far as I know, is a majestic
horror to which the botanists have given the very expressive name of
the prickly thistle (Cirsium ferox, D. C.). The moorlands of Provence
have nothing in their flora to equal its proud and menacing aspect.
In August this fierce-looking plant raises its voluminous white tufts
and with its lofty stature overtops the blue-green clumps of the
lavender, that lover of stony wastes. Spread in a rosette on the level
of the soil, the root-leaves, slashed into two series of narrow strips,
call to mind the backbones of a heap of big fish burnt up by the sun.
These strips are split into two divergent halves, of which one points
upwards and the other downwards, as though to threaten the passer-by
from every angle. The whole thing, from top to bottom, is a formidable
arsenal, a trophy of prickles, of pointed nails, of arrow-heads sharper
than needles.
What is the use of this savage panoply? Its discordance with the usual
vegetation accentuates the grace of the plants around it. By striking a
harsh and dissonant note, it contributes to the general harmony. The
haughty thistle is really superb, standing like a monument amidst the
humility of the lavender and thyme.
Others might see in this thicket of halberds a means of defence. But
what has the fierce thistle to defend, that it should bristle in this
way? Its seed? I doubt, indeed, whether the Goldfinch, the accredited
pilferer of the Carduaceæ, dare set foot on this horrid arsenal. He
would be spitted at once.
A humble Weevil will do what the bird dares not undertake and will do
it better. She will entrust her eggs to the white tufts; she will
destroy the seed of the ferocious plant, which, were it not subjected
to a severe thinning, would become an agricultural calamity.
At the beginning of July I cut off a well-flowered thistle-top; I dip
the stem in a bottle full of water and cover my repellent bouquet with
a wire-gauze cover, after stocking it with a dozen Weevils. The pairing
takes place. Soon the mothers dive down among the flowers and
seed-plumes.
A fortnight later, each head is feeding one to four larvæ, already far
advanced. Things go fast with the Larini: all must be finished before
the thistle-heads wither. September is not over by the time that the
insect has assumed the adult form; but there are still laggards at this
period, represented by nymphs and even by larvæ.
Built on the same plane as the Artichoke-weevil’s, the dwelling
consists of a sheath having for its base a basin hollowed in the
surface of the receptacle. In either case the architecture is the same;
so is the method of work. A quilt of hairs, borrowed from the
seed-plumes and the mane-like fringe of the receptacle, is heaped
around the grub and cemented with the lacquer of the intestine.
Outside this downy bed of wadding is spread a further mattress, a layer
of granular excrement. The artist has not thought fit to employ its
digestive refuse to greater advantage. It has something better at its
disposal. Like the other Larini, it is able to turn the sordid sewer
into a valuable glue- and varnish-factory.
Will this lodging, so softly padded, be its winter home? Not so. In
January I inspect the old thistle-heads; in none of them do I find the
Weevil. The autumnal population has migrated. For this I see a very
good reason.
The thistle, now dead and bare, an ash-grey ruin, is still standing, is
still holding out against the north-wind, thanks to its strength and
the firmness of its roots; but its flower-heads, emptied by age, are
wide open, exposing their contents to the inclemencies of the weather.
The fleece of the receptacle is a sponge that swells up with the rain
and tenaciously retains the moisture. The same may be said of the
cardoon and the artichoke.
In either case we no longer find the fortress of the carlina,
encompassed with convergent folioles; what we see is a spacious,
roofless ruin, abandoned to the damp and the cold. The white tuft of
the ferocious thistle and the blue tuft of the artichoke are delightful
villas in summer; in winter they are uninhabitable residences, sweating
mildew. Prudence, the safeguard of the humble, counsels the owners to
forestall the final dilapidation and to move. The advice is accepted.
At the approach of the rains and frosts, both Larini leave the home of
their birth and proceed to take up their winter-quarters elsewhere:
precisely where I do not know.