Funnily enough, I posted this link up for something else that it mentioned, though it mentions tear drinking moths there also.
Only this time it's elephant tears.....http://news.independent.co.uk/world/science_technology/article1787749.ece
"There are moths that drink the tears of elephants. Tears contain salt, water and trace levels of protein. Mabra elephantophila steals the tears without the elephants seeming to notice. Lobocraspis griseifusa does not wait for an animal's eyes to moisten - it sweeps its proboscis across the eye of its host, irritating the eyeball, encouraging it to produce tears."