Cool Critters: ‘Earliest’ appearance of butterflies turns heads this January

Every so often, unseasonably mild weather will rouse butterflies from hibernation earlier than usual in the Inland Northwest. But in January? That’s plain extraordinary.

Yet this is just what’s happening with a colorful little butterfly species known as the Milbert’s tortoiseshell. Flitting about on orange, black and brown wings against a backdrop of bare shrubs and dead grass, it causes people – including myself – to wonder if they’re seeing things.

January sightings have been documented on the Palouse, including in Pullman and Moscow, along with Spokane and the Yakima area – all due to our region’s unusually mild winter, said entomologist David James of Washington State University, co-author of the book “The Lives of Butterflies,” published in 2024.

The species – whose striking color pattern resembles that of a tortoiseshell cat – typically doesn’t emerge until March, he explained.

“To have Milbert’s tortoiseshells flying around in January in eastern Washington is very unusual, indeed,” James said.

In what may have been a once-in-a-lifetime event, James himself spotted one on Jan. 5 while hiking along the Snow Mountain Ranch trail, 12 miles west of Yakima.

During his 25 years of research, “Jan. 5 is the earliest I have seen a butterfly in Washington,” said James, adding that it was basking in a shaft of sunlight, trying to absorb as much heat as possible in the winter sun.

Social media users posted sightings of a bright orange and dark brown butterfly at Spokane’s Manito Park on Jan. 10 and again on Monday.

And on Wednesday, Gail Jacobs spotted one in Pullman while walking her dog near her home. Its blaze of color cut a striking contrast to the brown, crinkled landscape beneath it, she recalled.

“Suddenly I see this colorful butterfly flapping its wings – in the dead of winter! It was like seeing a fleeting fairy,” Jacobs said.

Summertime, with its ample warmth and nectar-producing flowers, is butterfly season. What these warm-loving insects do as temperatures drop depends on the species, James explained.

Most butterflies overwinter as caterpillars or eggs. Some, like monarchs and painted ladies, migrate long distances to warm winter homes. Others, such as Milbert’s tortoiseshells and mourning cloaks, retreat as adults to tree cavities, wood piles and rock crevices, and slip into a dormant state known as diapause.

Because butterflies can’t generate their own heat, they rely on external sources to warm their bodies so they can fly. Even though it’s January, weather conditions have resembled late February and March. Early last week, parts of the Inland Northwest saw high temperatures in the low-to-mid 50s. In fact, much of the west has seen warmer-than-average temperatures during the first half of the month, according to the National Oceanic and Atmospheric Administration.

When James spotted the Milton’s tortoiseshell on Jan. 5, it was sunny and 45 degrees, he recalled. Its body had likely reached a temperature warm enough to trick it into thinking it was time to emerge for spring, he said.

Except it’s not spring, there’s no flowers or nectar, and we’ll likely see snow before the end of winter. How will these butterflies survive?

Right now, they’re relying on reserves of fat stored in autumn, James said. They’re also drinking water and extracting minerals from puddles and mud.

“They’ll go back to dormancy when temperatures drop and the sun wanes,” James said.

With highs predicted to run near 40 degrees under partly-to-mostly sunny skies this week, Milton’s tortoiseshells may be out and about a little longer. If so, you might be lucky enough to see one basking in a sunny spot, its colorful wings wide open while absorbing heat from an unusually warm January sun.