‘It looked like … two [additional] eyes’

A scientist in New England found startling images captured by a trail camera, which show the first documented case of this strange behavior of insects in the region.

What’s going on?

“It’s almost 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 was describing a scene in which moths could be seen feeding on moose tears. He came across the surprising moment while reviewing camera trap footage in the Green Mountain National Forest.

The thirsty bugs were not indulging in schadenfreude, but in lachryphagy, or “tear eating”, 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 where it happened. Lachryphagy has long been assumed to occur almost exclusively in tropical climates. The observation of this behavior in Vermont confounds the still rather limited academic understanding of it.

According to Scientific American, there is only one other known and documented case of lachryphagy outside the tropics. That instance occurred in Arkansas.

So what is it about tears that bugs find so enticing? There is still no definitive answer, but one possible explanation is the unusually high protein content of tears, which is 200 times that of sweat.

Why is this concerning?

One of the biggest risks of lacriphagia comes from its potential to spread disease. Clarfeld and two co-authors published an article about the footage in Ekosphere in November. They postulated that “moths that visit the eyes can be vectors for the transmission of diseases such as keratoconjunctivitis, a condition that can lead to eye lesions in moose, with significant impacts on health.”

Moose are already at risk of afflictions such as chronic wasting disease, so they hardly need another source of infection. Furthermore, the dangers may increase as rising global temperatures expand the travel ranges of disease vectors.

What is being done to better understand lacriphagia?

There is still much to be learned about lachriphagia, especially now that it has been observed in a completely new type of climate. For scientists, a chance discovery is a call to further research and knowledge.

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

As in this case, cameras can also uncover previously unknown behaviors that can further our understanding of nature.

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