The Mason-Wasps

CHAPTER I. The Eumenes

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., 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. 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 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 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 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.

Continue reading The Mason-Wasps free in the Wunder reader →