It is a true dwelling, in which the larva may make a long stay.

The plastered walls betray as much.

Such precautions would be useless in the case of a simple exit abandoned as soon as made.

We cannot doubt that the burrow is a kind of meteorological observatory, and that its inhabitant takes note of the weather without.

Buried underground at a depth of twelve or fifteen inches, the larva, when ripe for escape, could hardly judge whether the meteorological conditions were favourable.