She hastens up at once.
Until then, not a movement: one would think that the animal was hypnotized by her watching.

At most, on the appearance of anything suspicious, she begins shaking her nest.

This is her way of inspiring the intruder with awe.

If I myself wish to provoke the singular alarm, I have but to tease the Epeira with a bit of straw.

You cannot have a swing without an impulse of some sort.