On The Moth's Inordinate Love For Salt

I am reading The Forest Unseen- A Year's Watch In Nature by David George Haskell.

During a vigil in the forest, a moth landed on the author's finger and refused to let go.. why? A passage from the book...

Only males have such an exaggerated antennae. They comb the air for scent released by females and fly upwind, guided to a mate by their enormous feathery noses. But finding a mate is not enough. The male must provide a nuptial offering to his mate. My finger provides him with an essential ingredient for this gift.

Diamonds may be the crystal of choice for wooing humans, but moths seek a different, altogether more practical mineral, salt. When the moth mates he will pass to his partner a package containing a ball of sperm and a packet of food. This food is generously seasoned with sodium, a precious gift that looks forward to the needs of the next generation. The female moth passes the salt to the eggs and thus to the caterpillars. Foliage is deficient in sodium, so the leaf-munching caterpillars need their parents salty bequest. The moth's arduous attachment to my finger prepares him for mating and will help his offspring survive. The salt in my sweat will make up for the deficiencies in caterpillar diets.

Full of nuggets like this... recommended.