CHAPTER I

THE MASON-WASPS

BY

J. HENRI FABRE

TRANSLATED BY

Alexander Teixeira de Mattos

FELLOW OF THE ZOOLOGICAL SOCIETY OF LONDON

NEW YORK

DODD, MEAD AND COMPANY

1919

CONTENTS

PAGE

TRANSLATOR’S NOTE v

CHAPTER

I THE EUMENES 1

II THE ODYNERI 28

III THE PELOPÆUS 60

IV THE AGENIÆ; THE PELOPÆUS’ VICTUALS 84

V ABERRATIONS OF INSTINCT 106

VI THE SWALLOW AND THE SPARROW 133

VII INSTINCT AND DISCERNMENT 155

VIII THE NEST-BUILDING ODYNERUS 176

IX INSECT GEOMETRY 219

X THE COMMON WASP 240

XI THE COMMON WASP (continued) 270

XII THE VOLUCELLA 288

INDEX 313

TRANSLATOR’S NOTE

This is the second volume on Wasps in the Collected Edition of Fabre’s

Souvenirs entomologiques. The first of these was The Hunting Wasps; and

the present volume is somewhat wilfully entitled, for all Wasps hunt in

varying degrees, if not on their own behalf, at least on that of their

young. My object, however, was to bring together all the essays

treating of those Wasps who actually build homes or nests, as distinct

from burrows. The last book on Wasps will be called More Hunting Wasps

and will be issued towards the end of the series.

For reasons which will be easily apparent to the reader, I have

reprinted the chapter called Instinct and Discernment, which was

included in Bramble-bees and Others, and that on the Volucella, which,

under the title of The Bumble-bee Fly, formed part of The Life of the

Fly. Apart from the two chapters named and the essay on the Eumenes,

which figures in The Wonders of Instinct, published in America by the

Century Co., none of the contents of this volume has until now appeared

in the English language. The Volucella is included by arrangement with

Mr. Fisher Unwin, the publisher of The Wonders of Instinct in England.

My thanks are due to the late Miss Frances Rodwell and to my friend

Bernard Miall, both of whom have been of great assistance to me in

preparing my translation.

Alexander Teixeira de Mattos.

CHELSEA, 18 April, 1919.

THE MASON-WASPS

CHAPTER I

THE EUMENES

A wasp-like garb of black and yellow; a slender, graceful figure; wings

that are not spread flat when resting, but are folded lengthwise in

two; the abdomen a sort of chemist’s retort, swelling into a gourd and

fastened to the thorax by a long neck which first distends into a pear

and then shrinks to a thread; a leisurely and silent flight; lonely

habits. There we have a summary sketch of the Eumenes. My part of the

country possesses two species: the larger E. Amadei, Lep., measures

nearly an inch in length; the other, E. pomiformis, Fabr., [1] is a

reduction of the first to half the scale.

Similar in form and colouring, both possess a like talent for

architecture; and this talent is expressed in a work of the highest

perfection, which charms the most untutored eye. Their dwelling is a

masterpiece. And yet the Eumenes follow the profession of arms, which

is unfavourable to artistic effort: they stab and sting a victim; they

pillage and plunder. They are predatory Wasps, victualling their larvæ

with caterpillars. It must be interesting to compare their habits with

those of the operator on the Grey Worm. [2] Though the

quarry—caterpillars in either case—remain the same, instinct, which is

liable to vary with the species, may have fresh glimpses in store for

us. Besides, the edifice built by the Eumenes in itself deserves

inspection.

The Hunting Wasps whose story we have told hitherto [3] are wonderfully

well-versed in the art of wielding the lancet; they astound us with

their surgical methods, which they seem to have learnt from some

physiologist who allows nothing to escape him; but these skilful

slayers have no merit as builders of dwelling-houses. What is their

home, in point of fact? An underground passage, with a cell at the end

of it; a gallery, an excavation, a shapeless cave. It is miner’s work,

navvy’s work: vigorous sometimes, artistic never. They use the pick for

loosening, the crowbar for shifting, the rake for extracting the

materials, but never the trowel for laying. Now in the Eumenes we see

real masons, who build their houses bit by bit with stone and mortar

and run them up in the open, either on firm rock or on the shaky

support of a bough. Hunting alternates with architecture; the insect is

a Nimrod or a Vitruvius [4] by turns.

And, first of all, what sites do these builders select for their homes?

Should you pass some little garden-wall, facing south, in a

sun-scorched corner, look at the stones which are not covered with

plaster, look at them one by one, especially the largest; examine the

masses of boulders, at no great height from the ground, where the

fierce rays have heated them to the temperature of a Turkish bath; and

perhaps, if you search long enough, you will light upon the structure

of Eumenes Amadei. The insect is scarce and lives apart; a meeting is

an event upon which we must not count with too great confidence. It is

an African species and loves the heat that ripens the carob and the

date. It haunts the sunniest spots and selects rocks or firm stones as

a foundation for its nest. Sometimes also, but seldom, it copies the

Chalicodoma of the Walls [5] and builds upon an ordinary pebble.

E. pomiformis is much more common and is comparatively indifferent to

the nature of the foundation on which she constructs her cell. She

builds on walls, on isolated stones, on the inner wooden surface of

half-closed shutters; or else she adopts an aerial base, the slender

twig of a shrub, the withered sprig of a plant of some sort. Any form

of support serves her purpose. Nor does she trouble about shelter. Less

chilly than her African cousin, she does not shun the unprotected

spaces exposed to every wind that blows.

When erected on a horizontal surface, where nothing interferes with it,

the structure of E. Amadei is a symmetrical cupola, a spherical

skull-cap, having at the top a narrow passage just wide enough for the

insect and surmounted by a neatly-funnelled neck. It suggests the round

hut of the Eskimo or of the ancient Gael, with its central chimney. An

inch, more or less, represents the diameter; three-quarters of an inch

the height. When the support is a perpendicular plane, the building

still retains the domed shape, but the entrance- and exit-funnel opens

at the side, upwards. The floor of this apartment calls for no labour:

it is supplied direct by the bare stone.

Having chosen the site, the builder erects a circular fence about an

eighth of an inch thick. The materials consist of mortar and small

stones. The insect selects its stone-quarry in some well-trodden path

or on some neighbouring highroad, at the driest, hardest spots. With

its mandibles, it scrapes together a small quantity of dust and soaks

it with saliva until the whole becomes a regular hydraulic mortar which

soon sets and is no longer susceptible to damp. The Mason-bees have

shown us a similar exploitation of the beaten paths and of the

road-mender’s macadam. All these open-air builders, all these erectors

of monuments exposed to wind and weather require an exceedingly dry

stone-dust; otherwise the material, already moistened with water, would

not properly absorb the liquid that is to give it cohesion; and the

edifice would soon be wrecked by the rains. They possess the sense of

discrimination shown by the plasterer, who rejects plaster injured by

the wet. We shall see presently how the insects that build under cover

avoid this laborious macadam-scraping and give the preference to fresh

earth already reduced to a paste by its own dampness. When common lime

answers our purpose, we do not trouble about Roman cement. Now Eumenes

Amadei requires a first-class cement, even superior to that of the

Chalicodoma of the Walls, for the work, when finished, does not receive

the thick outer casing wherewith the Mason-bee protects her cluster of

cells. And therefore the cupola-builder, as often as she can, uses the

highway as her stone-pit.

With the mortar, bricks are needed. These are bits of gravel of an

almost unvarying size—that of a pepper-corn—but of a shape and kind

that differ greatly, according to the places worked. Some are

sharp-cornered, with facets determined by chance fractures; some are

round, polished by friction under water. Some are of limestone, others

of flinty material. The favourite stones, when the neighbourhood of the

nest permits, are smooth, semitransparent little lumps of quartz. These

are selected with minute care. The insect weighs them, so to say,

measures them with the compass of its mandibles and does not accept

them until after making sure that they possess the requisite qualities

of size and hardness.

A circular fence, we were saying, is begun on the bare rock. Before the

mortar sets, which does not take long, the mason, as the work advances,

sticks a few stones into the soft mass. She dabs them half-way into the

cement, so as to leave them jutting out to a large extent, without

penetrating to the inside, where the wall must remain smooth for the

sake of the larva’s comfort. If necessary, she adds a little plaster,

to tone down any inner excrescences. The solidly-embedded stonework

alternates with the pure mortarwork, of which each fresh course

receives its facing of tiny encrusted pebbles. As the edifice is

raised, the builder slopes the construction a little towards the centre

and fashions the curve which will give the spherical shape. We employ

arched centerings to support the masonry of a dome while building; the

Eumenes, more daring than we, erects her cupola without any

scaffolding.

A round opening is contrived at the top; and above this opening rises a

funnelled mouth built of pure cement. It might be the graceful neck of

some Etruscan vase. When the cell is victualled and the egg laid, the

mouth is closed with a cement plug; and in this plug is set a little

pebble, one alone, no more: the ritual never varies. This work of

rustic architecture has naught to fear from the inclemencies of the

weather; it does not yield to the pressure of the fingers; it resists

the knife that attempts to remove it without breaking it. Its

nipple-shape and the bits of gravel wherewith it bristles all over the

outside remind one of certain cromlechs of olden time, of certain

tumuli whose domes are strewn with Cyclopean blocks of stone.

Such is the appearance of the edifice when the cell stands alone; but

the Wasp nearly always fixes other domes against her first, to the

number of five or six or more. This shortens the labour by allowing her

to use the same partition for two adjoining rooms. The original elegant

symmetry is lost and the whole now forms a cluster which, at first

sight, might be merely a clod of dry mud, sprinkled with little

pebbles. But examine the shapeless mass more closely; and we perceive

the number of chambers composing the habitation with the funnelled

mouths, each quite distinct and each furnished with its gravel stopper

set in the cement.

The Chalicodoma of the Walls employs the same building-methods as

Eumenes Amadei: in the courses of cement, she fixes, on the outside,

small stones of minor bulk. Her work begins by being a turret of rustic

art, not without a certain prettiness; then, when the cells are placed

side by side, the whole construction degenerates into a lump governed

apparently by no architectural rule. Moreover, the Mason-bee covers her

mass of cells with a thick layer of cement, which conceals the original

rockwork edifice. The Eumenes does not resort to this general coating:

her building is too strong to need it; she leaves the pebbly facings

uncovered, as well as the entrances to the cells. The two sorts of

nests, though constructed of similar materials, are therefore easily

distinguished.

The Eumenes’ cupola is a piece of artist’s work; and the artist would

be sorry to hide her masterpiece under whitewash. I crave forgiveness

for a suggestion which I advance with all the reserve befitting so

delicate a subject. Would it not be possible for the cromlech-builder

to take a pride in her handiwork, to look upon it with some affection

and to feel gratified by this evidence of her cleverness? Might there

not be an insect science of æsthetics? I seem at least to catch a

glimpse, in the Eumenes, of a propensity to beautify her product. The

nest must be first and foremost a solid habitation, an inviolable

stronghold; but, should ornament intervene without jeopardizing the

power of resistance, will the worker remain indifferent to it? Who

could say?

Let us set forth the facts. The orifice at the top, if left as a mere

hole, would suit the purpose quite as well as an elaborate door: the

insect would lose nothing in regard to facilities for coming and going

and would gain by shortening the labour. Yet we find, on the contrary,

the mouth of an amphora, gracefully curved, worthy of a potter’s wheel.

Choice cement and careful work are needed for the confection of its

slender, funnelled shaft. Why this nice finish, if the builder be

wholly absorbed in the solidity of her work?

Here is another detail: among the bits of gravel employed for the outer

covering of the cupola, grains of quartz predominate. They are polished

and translucent; they glitter slightly and please the eye. Why are

these little pebbles preferred to chips of limestone, when both

materials exist in equal abundance around the nest?

A yet more remarkable feature: we find pretty often, encrusted on the

dome, a few tiny empty Snail-shells, bleached by the sun. The species

usually selected by the Eumenes is one of the smaller Helices, Helix

strigata, frequent on our parched slopes. I have seen nests where this

Helix took the place of pebbles almost entirely. They were like boxes

made of shells, the work of a patient hand.

A comparison suggests itself. Certain Australian birds, notably the

Bower-birds, build themselves covered walks or arbours with interwoven

twigs and decorate the two entrances to the portico by strewing the

threshold with anything that they can find in the shape of glittering,

polished or bright-coloured objects. Every doorsill is a cabinet of

curiosities where the collector gathers smooth pebbles, variegated

shells, empty Snail-shells, Parrots’ feathers, bones that have come to

look like sticks of ivory. Even the odds and ends mislaid by man find a

home in the bird’s museum, where we see pipe-stems, brass buttons,

strips of cotton stuff and stone axe-heads.

The collection at either entrance to the bower is large enough to fill

half a bushel. As these things are of no use to the bird, its only

motive for accumulating them must be an art-lover’s hobby. Our common

Magpie has similar tastes: any shiny thing that he comes upon he picks

up, hides and hoards.

Well, the Eumenes, who shares this passion for bright pebbles and empty

Snail-shells, is the Bower-bird of the insect world; but she is a more

practical collector, knows how to combine the useful and the ornamental

and employs her discoveries in the construction of her nest, which is

both a fortress and a museum. When she finds bits of translucent

quartz, she rejects everything else: the building will be all the

prettier for them. When she comes across a little white shell, she

hastens to beautify her dome with it; should fortune smile and empty

Snail-shells abound, she encrusts the whole fabric with them, until it

becomes the supreme expression of her artistic taste. Is this so or

not? Who shall decide?

The nest of Eumenes pomiformis is the size of an average cherry and

constructed of pure mortar, without any outer pebblework. Its shape is

exactly similar to that which we have just described. When built upon a

large enough horizontal base, it is a dome with a central neck,

funnelled like the mouth of an urn. But, when the foundation is reduced

to a mere point, as on the twig of a shrub, the nest becomes a

spherical capsule, always, of course, surmounted by a neck. It is then

a miniature specimen of exotic pottery, a big-bellied alcarraza. Its

thickness is very slight, less than that of a sheet of paper; it

crushes under the least finger-pressure. The outside is not quite even.

It displays wrinkles and seams, due to the different courses of mortar,

or else knotty projections distributed almost concentrically.

Both Wasps accumulate caterpillars in their coffers, whether domes or

jars. Let us give an abstract of the bill of fare. These documents, for

all their dryness, possess a value: they will enable whoso cares to

interest himself in the Eumenes to perceive to what extent instinct

modifies the diet, according to place and season. The food is plentiful

but lacks variety. It consists of tiny caterpillars, by which I mean

the grubs of small Butterflies or Moths. This is proclaimed by the

structure, for we observe the usual caterpillar organism in the prey

selected by either Wasp. The body is composed of twelve segments, not

including the head. The first three have true legs, the next two are

legless, then come four segments with prolegs, two legless segments

and, lastly, a terminal segment with prolegs. It is exactly the same

organization which we saw in the Ammophila’s Grey Worm.

My old notes give the following description of the caterpillars found

in the nest of E. Amadei: a pale-green or, less often, yellowish body

covered with short white hairs; head wider than the front segment,

dead-black and also bristling with hairs. Length: 16 to 18 millimetres;

[6] width: about 3 millimetres. [7] It is more than a quarter of a

century since I jotted down this descriptive sketch; and today, at

Sérignan, I find in the Eumenes’ larder the same sort of game that I

saw long ago at Carpentras. Time and distance have not altered the

nature of the provisions.

I know one exception and one alone in this fidelity to the ancestral

diet. My observations mention a single dish that differs greatly from

those which accompany it. This is a caterpillar of the Looper group [8]

with only three pairs of prolegs, placed under the eighth, ninth and

twelfth segments. The body tapers slightly at either end, is contracted

at the junction of the different rings and is pale green with faint

black veinings, visible under the magnifying-glass, and a few sparse

black cilia. Length: 15 millimetres; [9] width: 2½ millimetres. [10]

E. pomiformis also has her preferences. Her game consists of small

caterpillars about 7 millimetres long by 1⅓ wide. [11] The body is pale

green, pretty sharply contracted at the junction of the segments. The

head is narrower than the rest of the body and is spotted with brown.

Pale ocellated circles are distributed in two transversal rows over the

middle segments and have a black dot in the centre, surmounted by a

black cilium. On the third and fourth and also on the penultimate

segment, each circle has two black dots and two cilia. This is the

rule.

The exception is supplied by two head of game in the whole course of my

observations. These two had a pale yellow body, with five longitudinal

brick-red stripes and a few very rare cilia. Head and prothorax brown

and shiny; length and diameter as above.

The number of pieces served for the meal of each larva interests us

more than the quality. In the cells of E. Amadei I find sometimes five

caterpillars and sometimes ten, which means a difference of a hundred

per cent in the quantity of the food, for the pieces are of exactly the

same size in both cases. Why this unequal supply, which gives a double

portion to one larva and a single portion to another? The consumers

have the same appetite: what one nurseling demands a second must

demand, unless there be here a menu differing according to the sexes.

In the perfect stage, the males are smaller than the females, are

hardly half as much in weight or volume. The amount of victuals,

therefore, required to bring them to their final development may be

reduced by one-half. In that case, the well-stocked cells belong to

females; the others, more meagrely supplied, belong to males.

But the egg is laid when the provisions are stored; and this egg has a

determined sex, although the most minute examination is not able to

discover the differences which will decide the hatching of a female or

a male. We are therefore needs driven to this strange conclusion: the

mother knows beforehand the sex of the egg which she is about to lay;

[12] and this knowledge enables her to fill the larder according to the

appetite of the future grub. What a strange world, so wholly different

from ours! We fall back upon a special sense to explain the Ammophila’s

hunting; what can we fall back upon to account for this intuition of

the future? Can the theory of chances play a part in the hazy problem?

If nothing is logically arranged with a foreseen object, how is this

clear vision of the invisible acquired?

The capsules of E. pomiformis are literally crammed with game. It is

true that the morsels are very small. My notes speak of fourteen green

caterpillars in one cell and sixteen in a second. I have no other

information about the integral diet of this Wasp, whom I have neglected

somewhat, preferring to study her cousin, the builder of rockwork

domes. As the two sexes differ in size, though not so greatly as in E.

Amadei, I am inclined to think that those two well-filled cells

belonged to females and that the males’ cells must have a less

sumptuous table. Not having seen for myself, I am content to set down

this mere suspicion.

What I have seen and often seen is the pebbly nest, with the larva

inside and the provisions partly consumed. To continue the rearing at

home and follow my charges’ progress from day to day was a business

which I could not resist; besides, so far as I was able to see, it was

easily managed. I had had some practice in this foster-father’s trade;

my association with the Bembex, the Ammophila, the Sphex [13] and many

others had turned me into a passable insect-breeder. I was no novice in

the art of dividing an old pen-box into compartments in which I laid a

bed of sand and on this bed the larva, with her provisions, delicately

removed from the maternal cell. Success was almost certain at each

attempt: I used to watch the larvæ at their meals, I saw my nurselings

grow up and spin their cocoons. Relying upon the experience thus

gained, I reckoned on success in raising my Eumenes.

The results, however, in no way answered to my expectations. All my

endeavours failed; and the larva allowed itself to die a piteous death

without touching its provisions.

I ascribed my reverse to this, that and the other cause: perhaps I had

injured the frail grub when demolishing the fortress; perhaps a

splinter of masonry bruised it when I forced open the hard dome with my

knife; perhaps a too-sudden exposure to the sun surprised it when I

withdrew it from the darkness of its cell; the open air again might

have dried up its moisture. I did the best I could to remedy all these

probable reasons of failure. I went to work with every possible caution

in breaking open the home; I cast the shadow of my body over the nest,

to save the grub from sunstroke; I at once transferred larva and

provisions into a glass tube and placed this tube in a box which I

carried in my hand, to minimize the jolting on the journey. Nothing was

of avail: the larva, when taken from its dwelling, always pined away

and died.

For a long time, I persisted in explaining my failure by the

difficulties attending the removal. The cell of Eumenes Amadei is a

strong casket which cannot be forced without sustaining a shock; and

the demolition of a work of this kind entails such varied accidents

that we are always liable to think that the grub has been bruised by

the wreckage. As for carrying home the nest intact on its support, with

a view to opening it with greater care than is permitted by a rough and

ready operation in the fields, that is out of the question: the nest

nearly always stands on an immovable rock or on some big stone forming

part of a wall. If I failed in my attempts at rearing, it was because

the larva had suffered when I was breaking up her house. The reason

seemed a good one; and I let it go at that.

In the end, another idea occurred to me and made me doubt whether my

rebuffs were always due to clumsy accidents. The Eumenes’ cells are

crammed with game: there are ten caterpillars in the cell of E. Amadei

and fifteen in that of E. pomiformis. These caterpillars, stabbed no

doubt, but stabbed in a fashion unknown to me, are not entirely

motionless. The mandibles seize upon what is presented to them, the

body buckles and unbuckles, the hinder half lashes out briskly when

stirred with the point of a needle. At what spot is the egg laid amid

that swarming mass, where thirty mandibles can make a hole in it, where

a hundred and twenty pair of legs can tear it? When the victuals

consist of a single head of game, these perils do not exist; and the

egg is laid on the victim not at hazard, but upon a judiciously chosen

spot. Thus, for instance, the Hairy Ammophila fixes hers, by one end,

across the Grey Worm, on the side of the first prolegged segment. The

egg hangs over the caterpillar’s back, away from the legs, whose

proximity might be dangerous. The worm, moreover, stung in the greater

number of its nerve-centres, lies on its side, motionless and incapable

of bodily contortions or sudden jerks of its hinder segments. If the

mandibles try to snap, if the legs give a kick or two, they find

nothing in front of them: the Ammophila’s egg is in the opposite

direction. The little grub is thus able, as soon as it hatches, to dig

into the giant’s belly in full security.

How different are the conditions in the Eumenes’ cell! The caterpillars

are imperfectly paralysed, perhaps because they have received but a

single stab; they toss about when touched with a pin; they are bound to

wriggle when bitten by the larva. If the egg is laid on one of them,

this first morsel will, I admit, be consumed without danger, on

condition that the point of attack be wisely chosen; but there remain

others which are not deprived of every means of defence. Let a movement

take place in the mass; and the egg, shifted from the upper layer, will

tumble into a trap of legs and mandibles. The least thing is enough to

jeopardize its existence; and this least thing has every chance of

being brought about in the disordered heap of caterpillars. The egg, a

tiny cylinder, transparent as crystal, is extremely delicate: a touch

withers it; the least pressure crushes it.

No, its place is not in the mass of provisions, for the caterpillars, I

repeat, are not sufficiently harmless. Their paralysis is incomplete,

as is proved by their contortions when I irritate them and evidenced

moreover by a very important fact. I have sometimes taken from the cell

of Eumenes Amadei a few head of game half-transformed into chrysalids.

It is evident that the transformation was effected in the cell itself

and therefore after the operation which the Wasp had performed upon

them. Whereof does this operation consist? I cannot say precisely,

never having seen the huntress at work. The sting most certainly has

played its part; but where? And how often? This is what we do not know.

What we can declare is that the torpor is not very profound, inasmuch

as the patient sometimes retains enough vitality to shed its skin and

become a chrysalis. Everything thus tends to make us ask by what

stratagem the egg is shielded from danger.

This stratagem I longed to discover; I would not be put off by the

scarcity of nests, by the irksomeness of the search, by the risk of

sunstroke, by the time taken up in the vain breaking open of unsuitable

cells; I meant to see and I saw. Here is my method: with the point of a

knife and a pair of nippers, I make a side opening, a window, beneath

the dome of E. Amadei and E. pomiformis. I work with the greatest care,

so as not to injure the recluse. I used to attack the cupola from the

top; I now attack it from the side. I stop when the breach is large

enough to allow me to see the state of things within.

What is this state of things? I pause to give the reader time to

reflect and to think out for himself a means of safety that will

protect the egg and afterwards the grub in the perilous conditions

which I have set forth. Seek, think and contrive, such of you as have

inventive minds. Have you guessed it? Do you give it up? I may as well

tell you.

The egg is not laid upon the provisions; it hangs from the top of the

cupola by a thread which vies with that of a Spider’s web for

slenderness. The dainty cylinder quivers and swings at the least

breath; it reminds me of the famous pendulum hung from the dome of the

Panthéon to prove the rotation of the earth. The victuals are heaped up

underneath.

Second act of this wondrous spectacle. In order to witness it, we must

open a window in cell after cell until fortune deigns to smile upon us.

The larva is hatched and already fairly large. Like the egg, it hangs

perpendicularly, by its rear-end, from the ceiling; but the

suspension-cord has gained considerably in length and consists of the

original thread eked out by a sort of ribbon. The grub is at dinner:

head downwards, it is digging into the limp belly of one of the

caterpillars. I touch up the game that is still intact with a straw.

The caterpillars grow restless. The grub forthwith retires from the

fray. And how? Marvel is added to marvel: what I took for a flat cord,

for a ribbon, at the lower end of the suspension-thread, is a sheath, a

scabbard, a sort of ascending gallery wherein the grub crawls backwards

and makes its way up. The cast shell of the egg, retaining its

cylindrical form and perhaps lengthened by a special operation on the

part of the new-born larva, forms this safety-channel. At the least

sign of danger in the heap of caterpillars, the larva retreats into its

sheath and climbs back to the ceiling, where the swarming rabble cannot

reach it. When peace is restored, it slides down its case and returns

to table, with its head over the viands and its rear upturned and ready

to withdraw in case of need.

Third and last act. Strength and vigour have come; the larva is sturdy

enough not to dread the movements of the caterpillars’ bodies. Besides,

the caterpillars, mortified by fasting and weakened by a prolonged

torpor, become more and more incapable of defence. The perils of the

tender babe are succeeded by the security of the lusty stripling; and

the grub, henceforth scorning its sheathed lift, lets itself drop upon

the game that remains. And thus the banquet ends in normal fashion.

That is what I saw in the nests of both species of Eumenes, that is

what I showed to friends who were even more surprised than I by these

ingenious tactics. The egg hanging from the ceiling, at a distance from

the provisions, has naught to fear from the caterpillars, which

flounder about below. The newly-hatched worm, whose suspension-cord is

lengthened by the sheath of the egg, reaches the game and takes a first

cautious bite at it. If there be danger, it climbs back to the ceiling

by retreating inside the scabbard. This explains the failure of my

earlier attempts. Not knowing of the safety-thread, so slender and so

easily broken, I gathered at one time the egg, at another the young

larva, after my inroads at the top had caused them to fall into the

midst of the live provisions. Neither of them was able to thrive when

brought into direct contact with the dangerous game.

If any one of my readers, to whom I appealed just now, has thought out

something better than the Eumenes’ invention, I beg that he will let me

know, for there is a curious parallel to be drawn between the

inspirations of reason and those of instinct.