Our failure, it seems to me, can be explained thus: outside the spacious front of the Anthophora's settlement, the Anthrax is in permanent residence. She visits, on the wing, every nook and corner, without moving away from the native cliff, because it would be useless to go farther. There is board and lodging here, indefinitely, for all her family. When some spot is deemed favorable, she hovers round inspecting it, then comes up suddenly and strikes it with the tip of her abdomen. The thing is done, the egg is laid. So I picture it, at least. Within a radius of a few yards and in a flight broken by short intervals of rest in the sun, she carries on her search of likely places for the laying and dissemination of her eggs. The insect's assiduous attendance upon the same slope is caused by the inexhaustible wealth of the locality exploited. The Anthrax of the Chalicodoma labors under very different conditions. Stay-at-home habits would be detrimental to her. With her rushing flight, made easy by the long and powerful spread of her wings, she must travel far and wide if she would found a colony. The bee's nests are not discovered in groups, but occur singly on their pebbles, scattered more or less everywhere over acres of ground. To find a single one is not enough for the fly: on account of the many parasites, not all the cells, by a long way, contain the desired larva; others, too well protected, would not allow of access to the provisions. Very many nests are necessary, perhaps, for the eggs of one alone; and the finding of them calls for long journeys. I therefore picture the Anthrax coming and going in every direction across the stony plain. Her practiced eye requires no slackened flight to distinguish the earthen dome which she is seeking. Having found it, she inspects it from above, still on the wing; she taps it once and yet once again with the tip of her ovipositor and forthwith makes off, without having set foot on the ground. Should she take a rest, it will be elsewhere, no matter where, on the soil, on a stone, on a tuft of lavender or thyme. Given these habits--and my observations in the Carpentras roads make them seem exceedingly probable--it is small wonder that the perspicacity of my young shepherds and myself should have come to naught. I was expecting the impossible: the Anthrax does not halt on the mason bee's nest to proceed with her laying in a methodical fashion; she merely pays a flying visit.