Butterflies drink crocodile tears for nutrition

Butterflies and bees hovering over crocodiles, elephants, and turtles are a common sight if you have watched even an hour of a wildlife TV show. I’ve always wondered why those annoying insects wouldn’t let go of their relatively large hosts. Turns out, drinking tears of these animals, quite unexpectedly, provides some very essential nutrients to many insects.

drinking tears crocodile tears interesting fact

What kind of nutrients could drinking tears provide?

Sodium, amino acids and other macronutrients like proteins are hard to find in nature. Moreover, butterflies and bees mostly consume nectar, which does not have a lot of salt. So to get enough salt for egg production and their metabolism, these insects are constantly on the look out for different sources.

There has been quite a bit of research on insects feeding on mammal tears. This phenomenon is known as lachryphagy. But the same scenario with reptiles as hosts is less documented.

In December 2014, Carlos de la Rosa, an aquatic ecologist from Costa Rica led a group of researchers and students on a boat trip down Costa Rica’s Puerto Viejo River. On the journey, they chanced upon a swarm of butterflies hovering over a lazy alligator basking in the sun on the banks of the river. You can check out their video of the incident below.

According to Carlos, who published his findings in the Frontiers in Ecology, these interactions could be an important element of the ecosystem. “We don’t know how essential these relationships are to the survival of those species. It could be that it’s just an occasional, fortuitous, or opportunistic source of salt. Or it could be essential.” he said. Due to the lack of research in this area, Carlos also called for more studies on the phenomenon. “Not a lot has been published on these topics, and all published reports indicate the need for further research…the scientific community has drifted very strongly toward high-tech types of studies [like] genomics,” he said. “And natural history itself, which is simple observations of events and phenomena in nature, has [been on the decline]. I’m all for technology, but it doesn’t replace the observations of phenomena in the field.”

Can these insects get their salts from some other source?

Yes. Depending on the insects’ immediate habitat, different species of insects can have different sources. They could derive their nutrients from the soil (mud-puddling), tears (lachryphagy), rotting plants, fruits, urine, feces and in some rare cases, even blood.

Butterflies mud puddling. It helps them get salts just like drinking tears.
Butterflies mud puddling at Aralam Wildlife Sanctuary, Kerala, India (Credits)

Why do they need these nutrients?

According to a research published in the sixteenth volume of Ecological Entomology in 1991, these salts and macronutrients play various roles in the physiology, ethology, and ecology of insects.  However, the need for consumption of these nutrients depends on the sexes and ages of the insects. As a matter of fact, males primarily dominate the consumption of this scarce resource. Male butterflies need to stay in flight more than their female counterparts and hence, have a greater need for sodium due to increased neuromuscular activity. Moreover, males also transferred these nutrients to females during mating. This transfer of nutrients eventually enhances the survival rate of the eggs.


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