So I took my stand at the foot of the rock, under a broiling sun, and for half a day I followed the movements of my Flies. They flitted quietly in front of the slope, a few inches away from the earthly covering. They went from one Bee’s nest to another, but without attempting to enter. For that matter, the attempt would be useless, for the galleries are too narrow to admit their spreading wings. So they simply explore the cliff, going to and fro, and up and down, with a flight that was now sudden, now smooth and slow. From time to time I saw one of them approach the wall and touch the earth suddenly with the tip of her body. The proceeding took no longer than the twinkling of an eye. When it was over the insect rested a moment, and then resumed flight. I was certain that, at the moment when the Fly tapped the earth, she laid her eggs on the spot. Yet, though I rushed forward and examined the place with my lens, I could see no egg. In spite of the closest attention I could distinguish nothing. The truth is that my state of exhaustion, together with the blinding light and scorching heat, made it difficult for me to see anything. Afterwards, when I made the acquaintance of the tiny thing that comes out of that egg, my failure no longer surprised me: for even in the leisure and peace of my study I have the greatest difficulty in finding the infinitesimal creature. How then could I see the egg, worn out as I was under the sun-baked cliff? None the less I was convinced that I had seen the Anthrax Flies strewing their eggs, one by one, on the spots frequented by the Bees who suit their grubs. They take no precaution to place the egg under cover, and indeed the structure of the mother makes any such precaution impossible. The egg, that delicate object, is laid roughly in the blazing sun, among grains of sand, in some wrinkle of the chalk. It is the business of the young grub to manage as best it can. The next year I continued my investigations, this time on the Anthrax of the Chalicodoma, a Bee that abounds in my own neighbourhood. Every morning I took the field at nine o’clock, when the sun begins to be unendurable. I was prepared to come back with my head aching from the glare, if only I could bring home the solution of my puzzle. The greater the heat, the better my chances of success. What gives me torture fills the insect with delight; what prostrates me braces the Fly. The road shimmers like a sheet of molten steel. From the dusty, melancholy olive-trees rises a mighty, throbbing hum, the concert of the Cicadæ, who sway and rustle with increasing frenzy as the temperature increases. The Cicada of the Ash adds its strident scrapings to the single note of the Common Cicada. This is the moment! For five or six weeks, oftenest in the morning, sometimes in the afternoon, I set myself to explore the rocky waste.