The Chingulays call these Humbosses.

Within they are full of hollow Vaults and Arches where they dwell and breed, and their nests are much like to Honeycombs, full of eggs and young ones.

These Humbosses are built with a pure refined Clay by the ingenious builders.

The people use this Clay to make their Earthen Gods of, because it is so pure and fine.
[The manner of their death.] This sort of creatures as they increase in multitudes, so they dy in multitudes also.

For when they come to maturity they have wings, and in the Evening after the going down of the Sun, (never before) all those that are fledged and ripe, will issue forth in such vast numbers, that they do almost darken the Sky, flying to such an height, as they go out of sight, and so keep flying till they fall down dead at last upon the Earth.