The Bembex comes straight down, with an imperceptible flight, as though letting herself drop inertly, buoyed up by the parachute of her wings. She is now hovering a hand’s breadth above the ground. This is the moment. The Midges take flight and all make for the rear of the Wasp; they hover in her wake, some nearer, some farther, in a geometrical line. If the Bembex turns to thwart their designs, they also turn, with a precision that keeps them in the rear on the same straight line; if she advances, they advance; if she retreats, they retreat, letting the Wasp set their pace all the time, now flying slowly, now coming to a standstill, according to the behaviour of their leader, the Bembex. They make no attempt to fling themselves on the object of their cupidity; their tactics are confined to keeping ready, in this rearguard position, which will save them any hesitation at the critical moment. Sometimes, wearying of this obstinate pursuit, the Bembex alights; the others instantly settle on the sand, still in the rear, and do not budge. The Wasp darts off again, with a shriller whimpering, a sign no doubt of increasing indignation; the Midges dart after her. One last method remains of throwing off the persistent Flies: dashing off at full speed, the Bembex flies far away, hoping perhaps to mislead the parasites by rapid evolutions across country. But the wary Gnats are not caught in the trap: they let her go and once more take up their positions on the sand around the burrow. When the Bembex returns, the same pursuit will begin all over again, until at last the parasites’ obstinacy has worn down the mother’s prudence. In that second when her vigilance is relaxed, the Flies are straightway there. One of them, occupying the most favourable spot, swoops upon the disappearing prey and the deed is done: the egg is laid.