Ants, who might damage the precious morsel in the lawful owner's
absence. After fixing her booty on the verdant pinnacle, the Pompilus
casts around for a favourable spot and digs her burrow. During the
process of excavation, she returns from time to time to her Spider;
she nibbles at the prize, feels, touches it here and there, as though
taking stock of its plumpness and congratulating herself on the
plentiful provender; then she returns to her burrow and goes on
digging. Should anything alarm or distress her, she does not merely
inspect her Spider: she also brings her a little closer to her work-
yard, but never fails to lay her on the top of a tuft of verdure.
These are the manoeuvres of which I can avail myself to gauge the
elasticity of the Wasp's memory.

While the Pompilus is at work on the burrow, I seize the prey and
place it in an exposed spot, half a yard away from its original
position. The Pompilus soon leaves the hole to enquire after her booty
and goes straight to the spot where she left it. This sureness of
direction, this faithful memory for places can be explained by
repeated previous visits. I know nothing of what has happened
beforehand. Let us take no notice of this first expedition; the others
will be more conclusive. For the moment, the Pompilus, without the
least hesitation, finds the tuft of grass whereon her prey was lying.
Then come marches and counter-marches upon that tuft, minute
explorations and frequent returns to the exact spot where the Spider
was deposited. At last, convinced that the prize is no longer there,
the Wasp makes a leisurely survey of the neighbourhood, feeling the
ground with her antennae as she goes. The Spider is descried in the
exposed spot where I had placed her. Surprise on the part of the
Pompilus, who goes forward and then suddenly steps back with a start: