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Crocodile tears are hard to come by, and new research reveals that butterflies and bees love the rare commodity.

Researchers found that the butterfly (Dryas iulia) and the bee (Centris sp.) are most likely found sitting on the head of a crocodile, relaxing on river banks and waiting for the spectacled caiman (Caiman crocodilus) to weep.

Aquatic ecologist Carlos de la Rosa and other researchers were was floating in Río Puerto Viejo in northeastern Costa Rica when they discovered butterflies placidly basking and fluttering next to the eyes of a crocodile.

"It was one of those natural history moments that you long to see up close," de la Rosa, the director of the La Selva Biological Station for the Organization for Tropical Field Studies in San Pedro, Costa Rica, said in a news release. "But then the question becomes, what's going on in here? Why are these insects tapping into this resource?"

Researcher explain that salt is a rare commodity to come by, especially when the seeker is land herbivore. This is why it's not rare to see butterflies sipping mineral-laden water from mud puddles. Animals sometimes collect salt and other rare minerals and proteins from sweat, tears, urine, and even blood of other animals when minerals are rare in their habitat.

De la Rosa had witnessed butterflies and moths in the Amazon feeding on the tears of turtles and a few caimans, but tear-drinking "lachryphagous" behavior in bees had only recently discovered by biologists.

"I did a Google search for images and I found out that it is quite common! A lot of people have recorded butterflies, and some bees, doing this," said de la Rosa.

"I have over 450 undescribed species from Costa Rica in my laboratory. If I did nothing for the rest of my life but collaborate with taxonomists and try to describe those, I would never get done," he said.

"I learned I have to carry a camera with me 24/7, because you never know what you're going to find when you're walking to the office or the dining hall," he explained.

He explains cameras can capture things by surprise.

"Those are the kinds of things that, you know, you don't plan for them, you can't plan for them," de la Rosa said. There was only one known species of dragonfly in the world that lives in bromeliads. Now there will be two. "You just keep your eyes open and have curiosity, and when you see something that doesn't seem to fit, dig."

The findings are published in the journal Frontiers in Ecology and the Environment.