In 1884, a white-letter hairstreak butterfly was spotted flitting about in Scotland. The critter, which boasts coffee-colored wings marked with a distinctive “W” zig-zag, was not seen again for more than a century. But at the beginning of August, a butterfly recorder snapped a photo of a Hairstreak munching on Ragwort near the village of Paxton, the BBC reports.
The elusive butterfly’s reappearance in Scotland was observed by one Iain Crowe, who is a member of the UK’s Butterfly Conservation, according to Sarah Devine of the Southern Reporter. Crowe said in a statement from the Butterfly Conservation organization that the Hairstreak was “a very ragged and worn individual found feeding on Ragwort in the grassy edge of an arable field.”
It isn’t the most flattering description, but the lone butterfly was nevertheless a welcome sight. The white-letter hairstreak, which is native to the UK, has come under severe threat in recent years. In 2016, the Press Association reported that the butterfly’s numbers have dropped 96 percent over the past four decades. Its decline has been linked to an outbreak of Dutch elm disease that was first recognized in the 1970s; the disease has killed millions of British elm trees, which is the food source for white-letter hairstreak caterpillars.
But the butterfly was a rarity even before the epidemic. Prior to 1884, there was only one other confirmed sighting of a white-letter hairstreak in Scotland, which occurred in 1859.
“It is not every day that something as special as this is found when out and about on a regular butterfly foray,” Crowe said of his recent discovery.
The Butterfly Conservation is now working to determine if the White-letter Hairstreak has established a breeding colony in the country. Its presence would bring the number of resident butterfly species in Scotland up to 34.
"Although Dutch elm disease occurs in Scotland, we still have a good amount of Wych elm, so hopefully it will prosper and spread,” says Paul Kirkland, director of Butterfly Conservation Scotland, in the statement. Butterfly fans may want to curb their enthusiasm, though. Kirkland said that the white-letter hairstreak’s reappearance in Scotland is “almost certainly” due to climate change.