I pluck the bird completely, the better to watch what happens; also, I cover the head with a paper hood to close the usual means of access.

For a long time, with jerky steps, the mother explores the body in every direction; she takes her stand by preference on the head, which she sounds by tapping on it with her front tarsi.

She knows that the openings which she needs are there, under the paper; but she also knows how frail are her grubs, how powerless to pierce their way through the strange obstacle which stops her as well and interferes with the work of her ovipositor.

The cowl inspires her with profound distrust.

Despite the tempting bait of the veiled head, not an egg is laid on the wrapper, slight though it may be.
Weary of vain attempts to compass this obstacle, the Fly at last decides in favour of other points, but not on the breast, belly, or back, where the hide would seem too tough and the light too intrusive.
She needs dark hiding-places, corners where the skin is very delicate.
The spots chosen are the cavity of the axilla, corresponding with our arm-pit, and the crease where the thigh joins the belly.