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Reaumur (Rene Antoine Ferchault de Reaumur (1683-1757), inventor of

the Reaumur thermometer and author of "Memoires pour servir a

l'histoire naturelle des insectes."--Translator's Note.) devoted one

of his papers to the story of the Chalicodoma of the Walls, whom he

calls the Mason-bee. I propose to go on with the story, to complete it

and especially to consider it from a point of view wholly neglected by

that eminent
bserver. And, first of all, I am tempted to tell how I

made this Bee's acquaintance.

It was when I first began to teach, about 1843. I had left the normal

school at Vaucluse some months before, with my diploma and all the

simple enthusiasm of my eighteen years, and had been sent to

Carpentras, there to manage the primary school attached to the

college. It was a strange school, upon my word, notwithstanding its

pompous title of 'upper'; a sort of huge cellar oozing with the

perpetual damp engendered by a well backing on it in the street

outside. For light there was the open door, when the weather

permitted, and a narrow prison-window, with iron bars and lozenge

panes set in lead. By way of benches there was a plank fastened to the

wall all round the room, while in the middle was a chair bereft of its

straw, a black-board and a stick of chalk.

Morning and evening, at the sound of the bell, there came rushing in

some fifty young imps who, having shown themselves hopeless dunces

with their Cornelius Nepos, had been relegated, in the phrase of the

day, to 'a few good years of French.' Those who had found mensa too

much for them came to me to get a smattering of grammar. Children and

strapping lads were there, mixed up together, at very different

educational stages, but all incorrigibly agreed to play tricks upon

the master, the boy master who was no older than some of them, or even


To the little ones I gave their first lessons in reading; the

intermediate ones I showed how they should hold their pen to write a

few lines of dictation on their knees; to the big ones I revealed the

secrets of fractions and even the mysteries of Euclid. And to keep

this restless crowd in order, to give each mind work in accordance

with its strength, to keep attention aroused and lastly to expel

dullness from the gloomy room, whose walls dripped melancholy even

more than dampness, my one resource was my tongue, my one weapon my

stick of chalk.

For that matter, there was the same contempt in the other classes for

all that was not Latin or Greek. One instance will be enough to show

how things then stood with the teaching of physics, the science which

occupies so large a place to-day. The principal of the college was a

first-rate man, the worthy Abbe X., who, not caring to dispense beans

and bacon himself, had left the commissariat-department to a relative

and had undertaken to teach the boys physics.

Let us attend one of his lessons. The subject is the barometer. The

establishment happens to possess one, an old apparatus, covered with

dust, hanging on the wall beyond the reach of profane hands and

bearing on its face, in large letters, the words stormy, rain, fair.

'The barometer,' says the good abbe, addressing his pupils, whom, in

patriarchal fashion, he calls by their Christian names, 'the barometer

tells us if the weather will be good or bad. You see the words written

on the face--stormy, rain--do you see, Bastien?'

'Yes, I see,' says Bastien, the most mischievous of the lot.

He has been looking through his book and knows more about the

barometer than his teacher does.

'It consists,' the abbe continues, 'of a bent glass tube filled with

mercury, which rises and falls according to the weather. The shorter

leg of this tube is open; the other...the other...well, we'll see.

Here, Bastien, you're the tallest, get up on the chair and just feel

with your finger if the long leg is open or closed. I can't remember

for certain.'

Bastien climbs on the chair, stands as high as he can on tip-toe and

fumbles with his finger at the top of the long column. Then, with a

discreet smile spreading under the silky hairs of his dawning


'Yes,' he says, 'that's it. The long leg is open at the top. There, I

can feel the hole.'

And Bastien, to confirm his mendacious statement, keeps wriggling his

forefinger at the top of the tube, while his fellow-conspirators

suppress their enjoyment as best they can.

'That will do,' says the unconscious abbe. 'You can get down, Bastien.

Take a note of it, boys: the longer leg of the barometer is open; take

a note of it. It's a thing you might forget; I had forgotten it


Thus was physics taught. Things improved, however: a master came and

came to stay, one who knew that the long leg of the barometer is

closed. I myself secured tables on which my pupils were able to write

instead of scribbling on their knees; and, as my class was daily

increasing in numbers, it ended by being divided into two. As soon as

I had an assistant to look after the younger boys, things assumed a

different aspect.

Among the subjects taught, one in particular appealed to both masters

and pupils. This was open-air geometry, practical surveying. The

college had none of the necessary outfit; but, with my fat pay--seven

hundred francs a year, if you please!--I could not hesitate over the

expense. A surveyor's chain and stakes, arrows, level, square and

compass were bought with my money. A microscopic graphometer, not much

larger than the palm of one's hand and costing perhaps five francs,

was provided by the establishment. There was no tripod to it; and I

had one made. In short, my equipment was complete.

And so, when May came, once every week we left the gloomy school-room

for the fields. It was a regular holiday. The boys disputed for the

honour of carrying the stakes, divided into bundles of three; and more

than one shoulder, as we walked through the town, felt the reflected

glory of those erudite rods. I myself--why conceal the fact?--was not

without a certain satisfaction as I piously carried that most delicate

and precious apparatus, the historic five-franc graphometer. The scene

of operations was an untilled, flinty plain, a harmas, as we call it

in the district. (Cf. "The Life of the Fly", by J. Henri Fabre,

translated by Alexander Teixeira de Mattos: chapter 1.--Translator's

Note.) Here, no curtain of green hedges or shrubs prevented me from

keeping an eye upon my staff; here--an indispensable condition--I had

not the irresistible temptation of the unripe apricots to fear for my

scholars. The plain stretched far and wide, covered with nothing but

flowering thyme and rounded pebbles. There was ample scope for every

imaginable polygon; trapezes and triangles could be combined in all

sorts of ways. The inaccessible distances had ample elbow-room; and

there was even an old ruin, once a pigeon-house, that lent its

perpendicular to the graphometer's performances.

Well, from the very first day, my attention was attracted by something

suspicious. If I sent one of the boys to plant a stake, I would see

him stop frequently on his way, bend down, stand up again, look about

and stoop once more, neglecting his straight line and his signals.

Another, who was told to pick up the arrows, would forget the iron pin

and take up a pebble instead; and a third deaf to the measurements of

angles, would crumble a clod of earth between his fingers. Most of

them were caught licking a bit of straw. The polygon came to a full

stop, the diagonals suffered. What could the mystery be?

I enquired; and everything was explained. A born searcher and

observer, the scholar had long known what the master had not yet heard

of, namely, that there was a big black Bee who made clay nests on the

pebbles in the harmas. These nests contained honey; and my surveyors

used to open them and empty the cells with a straw. The honey,

although rather strong-flavoured, was most acceptable. I acquired a

taste for it myself and joined the nest-hunters, putting off the

polygon till later. It was thus that I first saw Reaumur's Mason-bee,

knowing nothing of her history and nothing of her historian.

The magnificent Bee herself, with her dark-violet wings and black-

velvet raiment, her rustic edifices on the sun-blistered pebbles amid

the thyme, her honey, providing a diversion from the severities of the

compass and the square, all made a great impression on my mind; and I

wanted to know more than I had learnt from the schoolboys, which was

just how to rob the cells of their honey with a straw. As it happened,

my bookseller had a gorgeous work on insects for sale. It was called

"Histoire naturelle des animaux articules", by de Castelnau (Francis

Comte de Castelnau de la Porte (1812-1880), the naturalist and

traveller. Castelnau was born in London and died at Melbourne.--

Translator's Note.), E. Blanchard (Emile Blanchard (born 1820), author

of various works on insects, Spiders, etc.--Translator's Note.) and

Lucas (Pierre Hippolyte Lucas (born 1815), author of works on Moths

and Butterflies, Crustaceans, etc.--Translator's Note.), and boasted a

multitude of most attractive illustrations; but the price of it, the

price of it! No matter: was not my splendid income supposed to cover

everything, food for the mind as well as food for the body? Anything

extra that I gave to the one I could save upon the other; a method of

balancing painfully familiar to those who look to science for their

livelihood. The purchase was effected. That day my professional

emoluments were severely strained: I devoted a month's salary to the

acquisition of the book. I had to resort to miracles of economy for

some time to come before making up the enormous deficit.

The book was devoured; there is no other word for it. In it, I learnt

the name of my black Bee; I read for the first time various details of

the habits of insects; I found, surrounded in my eyes with a sort of

halo, the revered names of Reaumur, Huber (Francois Huber (1750-1831),

the Swiss naturalist, author of "Nouvelles observations sur les

abeilles." He early became blind from excessive study and conducted

his scientific work thereafter with the aid of his wife.--Translator's

Note.) and Leon Dufour (Jean Marie Leon Dufour (1780-1865), an army

surgeon who served with distinction in several campaigns, and

subsequently practised as a doctor in the Landes, where he attained

great eminence as a naturalist. Fabre often refers to him as the

Wizard of the Landes. Cf. "The Life of the Spider", by J. Henri Fabre,

translated by Alexander Teixeira de Mattos: chapter 1; and "The Life

of the Fly": chapter 1.--Translator's Note.); and, while I turned over

the pages for the hundredth time, a voice within me seemed to whisper:

'You also shall be of their company!'

Ah, fond illusions, what has come of you? (The present essay is one of

the earliest in the "Souvenirs Entomologiques."--Translator's Note.)

But let us banish these recollections, at once sweet and sad, and

speak of the doings of our black Bee. Chalicodoma, meaning a house of

pebbles, concrete or mortar, would be a most satisfactory title, were

it not that it has an odd sound to any one unfamiliar with Greek. The

name is given to Bees who build their cells with materials similar to

those which we employ for our own dwellings. The work of these insects

is masonry; only it is turned out by a rustic mason more used to hard

clay than to hewn stone. Reaumur, who knew nothing of scientific

classification--a fact which makes many of his papers very difficult

to understand--named the worker after her work and called our builders

in dried clay Mason-bees, which describes them exactly.

We have two of them in our district: the Chalicodoma of the Walls

(Chalicodoma muraria), whose history Reaumur gives us in a masterly

fashion; and the Sicilian Chalicodoma (C. sicula) (For reasons that

will become apparent after the reader has learnt their habits, the

author also speaks of the Mason-bee of the Walls and the Sicilian

Mason-bee as the Mason-bee of the Pebbles and the Mason-bee of the

Sheds respectively. Cf. Chapter 4 footnote.--Translator's Note.), who

is not peculiar to the land of Etna, as her name might suggest, but is

also found in Greece, in Algeria and in the south of France,

particularly in the department of Vaucluse, where she is one of the

commonest Bees to be seen in the month of May. In the first species

the two sexes are so unlike in colouring that a novice, surprised at

observing them come out of the same nest, would at first take them for

strangers to each other. The female is of a splendid velvety black,

with dark-violet wings. In the male, the black velvet is replaced by a

rather bright brick-red fleece. The second species, which is much

smaller, does not show this contrast of colour: the two sexes wear the

same costume, a general mixture of brown, red and grey, while the tips

of the wings, washed with violet on a bronzed ground, recall, but only

faintly, the rich purple of the first species. Both begin their

labours at the same period, in the early part of May.

As Reaumur tells us, the Chalicodoma of the Walls in the northern

provinces selects a wall directly facing the sun and one not covered

with plaster, which might come off and imperil the future of the

cells. She confides her buildings only to solid foundations, such as

bare stones. I find her equally prudent in the south; but, for some

reason which I do not know, she here generally prefers some other base

to the stone of a wall. A rounded pebble, often hardly larger than

one's fist, one of those cobbles with which the waters of the glacial

period covered the terraces of the Rhone Valley, forms the most

popular support. The extreme abundance of these sites might easily

influence the Bee's choice: all our less elevated uplands, all our

arid, thyme-clad grounds are nothing but water-worn stones cemented

with red earth. In the valleys, the Chalicodoma has also the pebbles

of the mountain-streams at her disposal. Near Orange, for instance,

her favourite spots are the alluvia of the Aygues, with their carpets

of smooth pebbles no longer visited by the waters. Lastly, if a cobble

be wanting, the Mason-bee will establish her nest on any sort of

stone, on a mile-stone or a boundary-wall.

The Sicilian Chalicodoma has an even greater variety of choice. Her

most cherished site is the lower surface of the projecting tiles of a

roof. There is not a cottage in the fields, however small, but

shelters her nests under the eaves. Here, each spring, she settles in

populous colonies, whose masonry, handed down from one generation to

the next and enlarged year by year, ends by covering considerable

surfaces. I have seen some of these nests, under the tiles of a shed,

spreading over an area of five or six square yards. When the colony

was hard at work, the busy, buzzing crowd was enough to make one

giddy. The under side of a balcony also pleases the Mason-bee, as does

the embrasure of a disused window, especially if it is closed by a

blind whose slats allow her a free passage. But these are popular

resorts, where hundreds and thousands of workers labour, each for

herself. If she be alone, which happens pretty often, the Sicilian

Mason-bee instals herself in the first little nook handy, provided

that it supplies a solid foundation and warmth. As for the nature of

this foundation, she does not seem to mind. I have seen her build on

the bare stone, on bricks, on the wood of a shutter and even on the

window-panes of a shed. One thing only does not suit her: the plaster

of our houses. She is as prudent as her kinswoman and would fear the

ruin of her cells, if she entrusted them to a support which might

possibly fall.

Lastly, for reasons which I am still unable to explain to my own

satisfaction, the Sicilian Mason-bee often changes the position of her

building entirely, turning her heavy house of clay, which would seem

to require the solid support of a rock, into an aerial dwelling. A

hedge-shrub of any kind whatever--hawthorn, pomegranate, Christ's

thorn--provides her with a foundation, usually as high as a man's

head. The holm-oak and the elm give her a greater altitude. She

chooses in the bushy clump a twig no thicker than a straw; and on this

narrow base she constructs her edifice with the same mortar that she

would employ under a balcony or the ledge of a roof. When finished,

the nest is a ball of earth, bisected by the twig. It is the size of

an apricot when the work of a single insect and of one's fist if

several have collaborated; but this latter case is rare.

Both Bees use the same materials: calcareous clay, mingled with a

little sand and kneaded into a paste with the mason's own saliva. Damp

places, which would facilitate the quarrying and reduce the

expenditure of saliva for mixing the mortar, are scorned by the Mason-

bees, who refuse fresh earth for building even as our own builders

refuse plaster and lime that have long lost their setting-properties.

These materials, when soaked with pure moisture, would not hold

properly. What is wanted is a dry dust, which greedily absorbs the

disgorged saliva and forms with the latter's albuminous elements a

sort of readily-hardening Roman cement, something in short resembling

the cement which we obtain with quicklime and white of egg.

The mortar-quarry which the Sicilian Mason-bee prefers to work is a

frequented highway, whose metal of chalky flints, crushed by the

passing wheels, has become a smooth surface, like a continuous

flagstone. Whether settling on a twig in a hedge or fixing her abode

under the eaves of some rural dwelling, she always goes for her

building-materials to the nearest path or road, without allowing

herself to be distracted from her business by the constant traffic of

people and cattle. You should see the active Bee at work when the road

is dazzling white under the rays of a hot sun. Between the adjoining

farm, which is the building-yard, and the road, in which the mortar is

prepared, we hear the deep hum of the Bees perpetually crossing one

another as they go to and fro. The air seems traversed by incessant

trails of smoke, so straight and rapid is the worker's flight. Those

on the way to the nest carry tiny pellets of mortar, the size of small

shot; those who return at once settle on the driest and hardest spots.

Their whole body aquiver, they scrape with the tips of their mandibles

and rake with their front tarsi to extract atoms of earth and grains

of sand, which, rolled between their teeth, become impregnated with

saliva and form a solid mass. The work is pursued so vigorously that

the worker lets herself be crushed under the feet of the passers-by

rather than abandon her task.

On the other hand, the Mason-bee of the Walls, who seeks solitude, far

from human habitations, rarely shows herself on the beaten paths,

perhaps because these are too far from the places where she builds. So

long as she can find dry earth, rich in small gravel, near the pebble

chosen as the site of her nest, that is all she asks.

The Bee may either build an entirely new nest on a site as yet

unoccupied, or she may use the cells of an old nest, after repairing

them. Let us consider the former case first. After selecting her

pebble, the Mason-bee of the Walls arrives with a little ball of

mortar in her mandibles and lays it in a circular pad on the surface

of the stone. The fore-legs and above all the mandibles, which are the

mason's chief tools, work the material, which is kept plastic by the

salivary fluid as this is gradually disgorged. In order to consolidate

the clay, angular bits of gravel, the size of a lentil, are inserted

separately, but only on the outside, in the as yet soft mass. This is

the foundation of the structure. Fresh layers follow, until the cell

has attained the desired height of two or three centimetres. (Three-

quarters of an inch to one inch.--Translator's Note.)

Man's masonry is formed of stones laid one above the other and

cemented together with lime. The Chalicodoma's work can bear

comparison with ours. To economise labour and mortar, the Bee employs

coarse materials, big pieces of gravel, which to her represent hewn

stones. She chooses them carefully one by one, picks out the hardest

bits, generally with corners which, fitting one into the other, give

mutual support and contribute to the solidity of the whole. Layers of

mortar, sparingly applied, hold them together. The outside of the cell

thus assumes the appearance of a piece of rustic architecture, in

which the stones project with their natural irregularities; but the

inside, which requires a more even surface in order not to hurt the

larva's tender skin, is covered with a coat of pure mortar. This inner

whitewash, however, is put on without any attempt at art, indeed one

might say that it is ladled on in great splashes; and the grub takes

care, after finishing its mess of honey, to make itself a cocoon and

hang the rude walls of its abode with silk. On the other hand, the

Anthophorae and the Halicti, two species of Wild Bees whose grubs

weave no cocoon, delicately glaze the inside of their earthen cells

and give them the gloss of polished ivory.

The structure, whose axis is nearly always vertical and whose orifice

faces upwards so as not to let the honey escape, varies a little in

shape according to the supporting base. When set on a horizontal

surface, it rises like a little oval tower; when fixed against an

upright or slanting surface, it resembles the half of a thimble

divided from top to bottom. In this case, the support itself, the

pebble, completes the outer wall.

When the cell is finished, the Bee at once sets to work to victual it.

The flowers round about, especially those of the yellow broom (Genista

scoparia), which in May deck the pebbly borders of the mountain

streams with gold, supply her with sugary liquid and pollen. She comes

with her crop swollen with honey and her belly yellowed underneath

with pollen dust. She dives head first into the cell; and for a few

moments you see some spasmodic jerks which show that she is disgorging

the honey-syrup. After emptying her crop, she comes out of the cell,

only to go in again at once, but this time backwards. The Bee now

brushes the lower side of her abdomen with her two hind-legs and rids

herself of her load of pollen. Once more she comes out and once more

goes in head first. It is a question of stirring the materials, with

her mandibles for a spoon, and making the whole into a homogeneous

mixture. This mixing-operation is not repeated after every journey: it

takes place only at long intervals, when a considerable quantity of

material has been accumulated.

The victualling is complete when the cell is half full. An egg must

now be laid on the top of the paste and the house must be closed. All

this is done without delay. The cover consists of a lid of pure

mortar, which the Bee builds by degrees, working from the

circumference to the centre. Two days at most appeared to me to be

enough for everything, provided that no bad weather--rain or merely

clouds--came to interrupt the labour. Then a second cell is built,

backing on the first and provisioned in the same manner. A third, a

fourth, and so on follow, each supplied with honey and an egg and

closed before the foundations of the next are laid. Each task begun is

continued until it is quite finished; the Bee never commences a new

cell until the four processes needed for the construction of its

predecessor are completed: the building, the victualling, the laying

of the egg and the closing of the cell.

As the Mason-bee of the Walls always works by herself on the pebble

which she has chosen and even shows herself very jealous of her site

when her neighbours alight upon it, the number of cells set back to

back upon one pebble is not large, usually varying between six and

ten. Do some eight grubs represent the Bee's whole family? Or does she

afterwards go and establish a more numerous progeny on other boulders?

The surface of the same stone is spacious enough to provide a support

for further cells if the number of eggs called for them; the Bee could

build there very comfortably, without hunting for another site,

without leaving the pebble to which she is attached by habit and long

acquaintance. It seems to me therefore, exceedingly probable that the

family is a small one and that it is all installed on the one stone,

at any rate when the Mason-bee is building a new home.

The six to ten cells composing the cluster are certainly a solid

dwelling, with their rustic gravel covering; but the thickness of

their walls and lids, two millimetres (.078 inch--Translator's Note.)

at most, seems hardly sufficient to protect the grubs against the

inclemencies of the weather. Set on its pebble in the open air,

without any sort of shelter, the nest will have to undergo the heat of

summer, which will turn each cell into a stifling furnace, followed by

the autumn rains, which will slowly wear away the stonework, and by

the winter frosts, which will crumble what the rains have respected.

However hard the cement may be, can it possibly resist all these

agents of destruction? And, even if it does resist, will not the

grubs, sheltered by too thin a wall, have to suffer from excess of

heat in summer and of cold in winter?

Without arguing all this out, the Bee nevertheless acts wisely. When

all the cells are finished, she builds a thick cover over the group,

formed of a material, impermeable to water and a bad conductor of

heat, which acts as a protection at the same time against damp, heat

and cold. This material is the usual mortar, made of earth mixed with

saliva, but on this occasion with no small stones in it. The Bee

applies it pellet by pellet, trowelful by trowelful, to the depth of a

centimetre (.39 inch--Translator's Note.) over the cluster of cells,

which disappear entirely under the clay covering. When this is done,

the nest has the shape of a rough dome, equal in size to half an

orange. One would take it for a round lump of mud which had been

thrown and half crushed against a stone and had then dried where it

was. Nothing outside betrays the contents, no semblance of cells, no

semblance of work. To the inexperienced eye, it is a chance splash of

mud and nothing more.

This outer covering dries as quickly as do our hydraulic cements; and

the nest is now almost as hard as a stone. It takes a knife with a

strong blade to break open the edifice. And I would add, in

conclusion, that, under its final form, the nest in no way recalls the

original work, so much so that one would imagine the cells of the

start, those elegant turrets covered with stucco-work, and the dome of

the finish, looking like a mere lump of mud, to be the product of two

different species. But scrape away the crust of cement and we shall

easily recognize the cells below and their layers of tiny pebbles.

Instead of building a brand-new nest, on a hitherto unoccupied

boulder, the Mason-bee of the Walls is always glad to make use of the

old nests which have lasted through the year without suffering any

damage worth mentioning. The mortar dome has remained very much what

it was at the beginning, thanks to the solidity of the masonry, only

it is perforated with a number of round holes, corresponding with the

chambers, the cells inhabited by past generations of larvae. Dwellings

such as these, which need only a little repair to put them in good

condition, save a great deal of time and trouble; and the Mason-bees

look out for them and do not decide to build new nests except when the

old ones are wanting.

From one and the same dome there issue several inhabitants, brothers

and sisters, ruddy males and black females, all the offspring of the

same Bee. The males lead a careless existence, know nothing of work

and do not return to the clay houses except for a brief moment to woo

the ladies; nor do they reck of the deserted cabin. What they want is

the nectar in the flower-cups, not mortar to mix between their

mandibles. There remain the young mothers, who alone are charged with

the future of the family. To which of them will the inheritance of the

old nest revert? As sisters, they have equal rights to it: so our code

would decide, since the day when it shook itself free of the old

savage right of primogeniture. But the Mason-bees have not yet got

beyond the primitive basis of property, the right of the first


When, therefore, the laying-time is at hand, the Bee takes possession

of the first vacant nest that suits her and settles there; and woe to

any sister or neighbour who shall henceforth dare to contest her

ownership. Hot pursuits and fierce blows will soon put the newcomer to

flight. Of the various cells that yawn like so many wells around the

dome, only one is needed at the moment; but the Bee rightly calculates

that the others will be useful presently for the other eggs; and she

watches them all with jealous vigilance to drive away possible

visitors. Indeed I do not remember ever seeing two Masons working on

the same pebble.

The task is now very simple. The Bee examines the old cell to see what

parts require repairing. She tears off the strips of cocoon hanging

from the walls, removes the fragments of clay that fell from the

ceiling when pierced by the last inhabitant to make her exit, gives a

coat of mortar to the dilapidated parts, mends the opening a little;

and that is all. Next come the storing, the laying of the eggs and the

closing of the chamber. When all the cells, one after the other, are

thus furnished, the outer cover, the mortar dome, receives a few

repairs if it needs them; and the thing is done.

The Sicilian Mason-bee prefers company to a solitary life and

establishes herself in her hundreds, very often in many thousands,

under the tiles of a shed or the edge of a roof. These do not

constitute a true society, with common interests to which all attend,

but a mere gathering, where each works for herself and is not

concerned with the rest, in short, a throng of workers recalling the

swarm of a hive only by their numbers and their eagerness. The mortar

employed is the same as that of the Mason-bee of the Walls, equally

unyielding and waterproof, but thinner and without pebbles. The old

nests are used first. Every free chamber is repaired, stocked and

sealed up. But the old cells are far from sufficient for the

population, which increases rapidly from year to year. Then, on the

surface of the nest, whose chambers are hidden under the old general

mortar covering, new cells are built, as the needs of the laying-time

call for them. They are placed horizontally, or nearly so, side by

side, with no attempt at orderly arrangement. Each architect has

plenty of elbow-room and builds as and where she pleases, on the one

condition that she does not hamper her neighbours' work; otherwise she

can look out for rough handling from the parties interested. The

cells, therefore, accumulate at random in this workyard where there is

no organization. Their shape is that of a thimble divided down the

middle; and their walls are completed either by the adjoining cells or

by the surface of the old nest. Outside, they are rough and display

successive layers of knotted cords corresponding with the different

courses of mortar. Inside, the walls are flat without being smooth;

later on, the grub's cocoon will make up for any lack of polish.

Each cell, as built, is stocked and walled up immediately, as we have

seen with the Mason-bee of the Walls. This work goes on throughout the

best part of May. All the eggs are laid at last; and then the Bees,

without drawing distinctions between what does and what does not

belong to them, set to work in common on a general protection for the

colony. This is a thick coat of mortar, which fills up the gaps and

covers all the cells. In the end, the common nest presents the

appearance of a wide expanse of dry mud, with very irregular

protuberances, thicker in the middle, the original nucleus of the

establishment, thinner at the edges, where as yet there are only newly

built cells, and varying greatly in dimensions according to the number

of workers and therefore to the age of the nest first founded. Some of

these nests are hardly larger than one's hand, while others occupy the

greater part of the projecting edge of a roof and are measured by

square yards.

When working alone, which is not unusual, on the shutter of a disused

window, on a stone, or on a twig in some hedge, the Sicilian

Chalicodoma behaves in just the same way. For instance, should she

settle on a twig, the Bee begins by solidly cementing the base of her

cell to the slight foundation. Next, the building rises, taking the

form of a little upright turret. This first cell, when victualled and

sealed, is followed by another, having as its support, in addition to

the twig, the cells already built. From six to ten chambers are thus

grouped side by side. Lastly, one coat of mortar covers everything,

including the twig itself, which provides a firm mainstay for the