Scotland: Exquisite and Endangered Butterfly That Lays Eggs the Size of Salt Grains Found Breeding for First Time in 130 Years

A white-letter hairstreak butterfly photo from 2016 shows the insect’s notable white-and-orange coloring. AJC1 on Flickr

A small butterfly, about the size of your thumb, hasn't bred in Scotland in more than 130 years—until now.

Tiny eggs the size of salt grains from the Satyrium w-album butterfly species, more commonly referred to as the white-letter hairstreak, were found on elm trees in Berwickshire County in Scotland, The Guardian reported. This comes after they were spotted last year in the country for the first time since 1884.

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"Last year was an impossible find, but this year's egg discovery is beyond anything we thought possible," Iain Cowe, who helps monitor the insect's activity for the Butterfly Conservation group in Scotland, told the paper.

This nearly impossible sighting was spotted by Butterfly Conservation volunteers Jill Mills and Ken Haydock.

"We were searching the elm trees by the River Tweed at Lennel when Jill called me over," Haydock said in The Guardian. "I could see by the look on her face that she had found something. River Tweed is a body of water located in southeastern Scotland.

What she found were the eggs as well as remains from a hatched shell, which means it's possible breeding began before now. This seems to indicate a possible resurgence of the butterfly, but Paul Kirkland, director of Butterfly Conservation Scotland, believes it's too early for such a conclusion.

"We will need to have a few more years of confirmed sightings before we can officially class this butterfly as a resident species in Scotland," he wrote in a blog post on the organization's website. "If this happens, it would take the total number of butterflies found in Scotland to 34, which really would be something to celebrate."

Although the butterflies have been reported by multiple outlets as endangered in Scotland, they can be found in England, according to Butterfly Conservation.

This surprising discovery does raise a few major questions: Why are the butterflies back? And how did they get to Scotland?

"Those butterflies don't move great distances," ecologist Orley Taylor at The University of Kansas told Newsweek. He has not studied the white-Letter hairstreak, but has done prior research on this particular genus.

Taylor notes this sort of discovery isn't unheard of. "It happens to a lot of species," he explained.

According to Taylor, you would have to find where the nearest population of white-letter hairstreak butterflies resided to determine if they arrived of their own accord.

"The White-letter Hairstreak lays its eggs on a leaf bud so when they hatch they have food at their feet. A butterfly actually obliged and laid an egg in front of a tree expert in July last year when they came to visit to see if our claims that they were in the tree were true."

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"If you're talking about [a] 100-mile gap, that's a big gap for a butterfly like this."

You'd also look at other factors, like whether trees housing the butterflies or their eggs were transported into the area.

And there's another possibility that's a little less mysterious.

"Was it simply a failure to notice that the butterfly was always present?" he wondered.

Taylor explained that scientists don't know a lot about this particular genus of butterfly as they don't regularly make trips to flowers, preferring to stay up in trees. The insects are small, flit around quickly and lay their eggs at the top of trees, which makes them hard to collect. Taken together, he doesn't rule out the possibility that they have always been present in Scotland.

Still, he doesn't discount the finding.

"I think it's pretty cool if it shows up in Scotland after 130 years," he said.