My first observation was made in the engine-room of a silk-factory. The back of the boiler reached nearly to the ceiling, the space between being barely twenty inches. It was against this ceiling, right above the huge cauldron, which was always full of water and steam at a high temperature, that the Pelopæus-nest was fixed. At this spot the thermometer marked 120°. This degree of heat was maintained all through the year; it was only at night and on holidays that it decreased.
A country distillery furnished me with the second subject of observation. It combined two excellent conditions for attracting Pelopæi: rural quiet and the heat of a furnace. The nests therefore were numerous, fixed more or less everywhere on [[71]]anything that came to hand, even down to the pile of account-books in which the excisemen registered their troublesome inspections of the proof-spirit. One of these, situated quite close to the still, was tested with the thermometer. It measured 113° of heat.
These few data prove that the larvæ of the Pelopæus are comfortable in a temperature of a hundred degrees or over, a temperature not accidental, like that produced by a fire blazing in a chimney, but constant, such as obtained by a boiler or a still. Tropical heat is favourable to the grub slumbering for ten months in its mud hole. Any seed, in order to sprout, needs a certain quantum of heat, greater or smaller according to its kind. The larva, a sort of animal seed out of which the perfect insect will come by a process of germination even more wonderful than that which turns an acorn into an oak, the larva also claims its quantum of heat. The larva of the Pelopæus can cheerfully endure a temperature that makes the baobab or the oily palm-tree sprout. What then is the origin of this chilly tribe?
A good fire on the hearth, a boiler or a furnace shedding an artificial tropical [[72]]climate around them are useful windfalls, which, however, cannot be relied upon; and the Pelopæus settles in any lodging where she finds warmth and not too garish a light. The corners of a conservatory; a kitchen-ceiling; the embrasure of a window with closed casement and shutters, provided that these furnish some exit-hole; the rafters of a loft, where the warmth of the daily quota of sunshine is preserved by the heaped-up hay and straw; the walls of a cottage bedroom: any of these suit her, so long as the larvæ find a snug shelter in winter. This climatological expert, the daughter of the dog-days, divines the coming peril for her family, that inclement season which she herself will never see.
While she is scrupulous in her choice of a warm spot, on the other hand she is supremely indifferent to the nature of the foundation on which the nest is to be fastened. As a rule, she fixes her groups of cells to the stonework, whether rough-coated or not, and to the timber, whether bare or plastered; but she uses many other supports, some of which are very peculiar. Let us mention a few of these fantastic installations.
My notes speak of a nest constructed inside [[73]]a gourd standing on the mantelpiece of a farm-kitchen. In this narrow-mouthed receptacle the farmer used to keep his shot. As the orifice was always open and the utensil not employed at that time of year, a Pelopæus had found that the peaceful retreat suited her and had gone to the length of building on the layer of small-shot. The gourd had to be broken to extract the bulky edifice.
The same notes tell me of nests built against the pile of account-books in a distillery; in a fur cap relegated to the wall until the return of winter; in the hollow of a brick, back to back with the downy structure of a Cotton-bee; on the sides of a bag of oats; in a piece of lead tubing broken off from an old water-pipe.
I saw something more remarkable still in the kitchen at Roberty, one of the biggest farms near Avignon. It was a large room with a very wide fireplace, in which the soup for the farm-hands and the food for the cattle were simmering in a row of pots and pans. The labourers used to come in from the fields so many at a time, take their seats on benches round the table and devour the portions served to them, with the silent haste that denotes a keen appetite. To enjoy [[74]]this half-hour of comfort, they would take off their hats and smocks and hang them on pegs on the wall. Short though the meal was, it lasted long enough to allow the Pelopæi to inspect the garments and take possession of them. The inside of a straw hat was recognized as a most useful retreat; the folds of a smock were looked upon as a shelter which could be turned to excellent account; and the work of building started forthwith. On rising from table, one of the men would shake his smock, another his hat, to rid it of a heap of mud that was already the size of an acorn.
When the labourers had gone, I had a talk with the cook. She told me of her tribulations: those impudent Bugs were all over the place, dirtying everything with their filth. She was chiefly concerned about the window-curtains. Dabs of mud on the ceiling, on the walls, on the chimneypiece you could put up with; but it was a very different matter when you found them on the linen and the curtains. To keep the curtains clean and dislodge the wretched things who persisted in bringing in their bits of mud, she had to shake them every day, to beat them with a bamboo. And it was all no use: next morning, work was resumed [[75]]with equal vigour on the buildings destroyed the day before.
I sympathized with her sorrows, while greatly regretting that I could not myself take charge of the place. How gladly I would have left the Pelopæi undisturbed, though they covered every scrap of upholstery with mud; how willingly I would have let them have their way, so that I might learn what prospects there are for a nest if perched on the shifting support of a coat or a curtain! The Mason-bee of the Shrubs,[1] heedless of the storm, builds on a twig; but her edifice, constructed of hard mortar, envelops the support, surrounds it on every side and becomes firmly fixed to it. The nest of the Pelopæus is a mere blob of mud, fastened to its support without any special adhesive preparation. It has no hydraulic cement which sets as soon as used, no foundations welded to the supporting base. How can such a method give proper stability? The nests which I find on the coarse canvas of corn-bags come off at the least shake, though the rough mesh of the stuff makes it easier for them to stick on: what will happen when the nests are placed on a piece of fine calico hanging [[76]]perpendicularly and often flicked about, if only by the draught? To build on that strikes me as an aberration of instinct on the part of the architect, who has not yet learnt, in spite of the long lesson of the ages, how perilous are certain sites in human habitations.