In the woods, sometimes, swarms of butterflies hover over a patch of earth. This behaviour is called mud-puddling, or just puddling, and is often seen in butterflies, a few months and other insects searching for moisture, salt and other nutrients.
Some are attracted by wet sand, dung or carrion.
In some species, males may hover over sodium- rich slough and repeatedly take up liquid, voiding it after absorbing the valuable salt.
Salt is otherwise scarce in a diet of plants and nectar. It is believed that the minerals may play a key role in mating and reproduction. Often the male transfers the salt to the female upon mating, to be incorporated into the eggs.