‘Looked like … two [additional] eyes’

A New England scientist came across surprising footage captured by a game camera, showing the first documented case of this strange insect behavior in the region.

What’s going on?

“It almost looked like the moose had two [additional] eyes,” Laurence Clarfeld, an environmental researcher at the University of Vermont, told Scientific American. “At first I wasn’t sure what it was.”

Clarfeld described a scene in which moths could be seen feeding on moose tears. He had experienced this surprising moment while viewing images from a camera trap in the Green Mountain National Forest.

The thirsty insects were not engaging in schadenfreude, but in lachryphagia, or “eating tears,” a process by which moths and other insects feed on the tears of larger animals, even humans.

And yet, it is not the act itself that is remarkable, but the place where it occurred. Larphagia has long been assumed to occur almost exclusively in tropical climates. The observation of this behavior in Vermont confuses the still rather limited scientific understanding of this phenomenon.

According to Scientific American, there is only one other known and documented case of larphagia outside of the tropics. This example occurred in Arkansas.

So what is it about tears that attracts insects so much? There is no definitive answer yet, but one possible explanation is the unusually high protein content of tears, which is 200 times higher than that of sweat.

Why is this concerning?

One of the biggest risks of larphagia comes from its potential for spreading disease. Clarfeld and two co-authors published a paper on the images in Ecosphere in November. They proposed that “eye-visiting butterflies may be vectors for the transmission of diseases such as keratoconjunctivitis, a disease that can induce eye damage in moose, with significant health consequences.”

Moose are already at risk for conditions such as chronic wasting disease, so they have little need for another source of infection. Additionally, dangers could increase as rising global temperatures expand the areas where disease vectors travel.

What can we do to better understand larphagia?

There is still much to learn about larphagia, especially now that it has been observed in a completely new type of climate. For scientists, this chance discovery is a call for further research and awareness.

It’s also a reminder of why trail cameras are among the most powerful tools in wildlife research. A well-placed camera can reveal extremely valuable information about the population and status of a species in an area.

As in this case, cameras can also discover previously unknown behaviors that could improve our understanding of nature.

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