The spot which she adopts varies greatly; often it is an extremely curious one, the one positive condition being that the temperature should be mild and equable. A furnace heat appears to suit the Pelopæus’ larvæ; at least, the favourite place is the chimney, on either side of the flue, up to a height of twenty inches or so. This snug shelter has its drawbacks. The smoke gets to the nests, especially during the winter, when fires are going all day, and gives them a glaze of brown or black similar to that which covers the stonework. They are so like it in appearance that they might well be taken for inequalities in the mortar which have been overlooked by the trowel. This swarthy distempering is not a serious matter, provided that the flames do not lick against the cluster of cells. That would ensure the destruction of the larvæ, stewed to death in their clay pots. But this danger appears to be foreseen; and the Pelopæus entrusts her family only to chimneys which are too wide for anything but smoke to reach their sides; she is suspicious of the narrow ones which allow the flames to fill the whole entrance to the flue. In spite of her caution, one peril remains. While the nest is building, at a moment when the Wasp, urged by the need for laying her eggs, cannot bring herself to cease working, it sometimes happens that the approach to the dwelling is barred to her for a time, or even for the whole day, either by a curtain of steam rising from a stew-pan or by clouds of smoke resulting from damp firewood. Washing-days are the most risky. From morning to night, the housewife keeps the huge cauldron boiling with all the odds and ends of the wood-shed: chips, bits of bark, leaves, fuel that burns with difficulty and intermittently. The smoke from the hearth, the steam from the cauldron and the reek from the wash-tub form in front of the fireplace a dense mist with very few rifts in it. I have at rare intervals surprised the Pelopæus in the presence of some such obstacle. It is told of the Water-ouzel, the Dipper, that, to get back to his nest, he will fly through the cataract under a mill-weir. The Pelopæus is even more daring: with her pellet of mud in her teeth, she crosses the cloud of smoke and disappears behind it, henceforth invisible, so thick is the screen. A spasmodic chirring, her working-song, alone betrays the mason at her task. The building rises mysteriously behind the cloud. The ditty ceases and the Wasp emerges from the steam-flakes, fit and well, as though coming out of a limpid atmosphere. She has faced the fire, like the fabled Salamander, and she will face it all day, until the cell is built, crammed with victuals and closed.