This particular adventure begins with the search for a bird. However, like many discoveries that have gone somewhat off course, birder Chris Lindsey found something far more interesting: a western blue dwarf butterfly. The smallest butterfly in North America.
On September 3rd, Lindsey was in an area north of Walla Walla that he does not normally wander through when he first spotted the tiny butterfly. He had finally pushed his way through a pile of steppe grass and bushes when he noticed the butterfly – its fairytale wingspan smaller than a thumbnail.
“I went through this habitat that was like the worst habitat. It was just very disturbed and had a whole bunch of weeds. It’s an area where nobody would really look for butterflies,” Lindsey said.
Lindsey had seen plenty of western pygmy blues while attending pharmacy school in Southern California. The butterflies are found year-round in the Southwest, including parts of Texas, New Mexico, Arizona, and southern California. Western Pygmy Blues expand their range in spring and summer, often flying as far south as southern Oregon.
Entomologists said they weren’t sure how this range expansion came about. Perhaps winds are carrying the butterflies north, said David James, an entomologist at Washington State University.
Lindsey had read enough field guides to know that sighting a western pygmy blue this far north could be something very special. So he snapped some photos and started asking around.
Other butterfly enthusiasts told Lindsey that the Western Pygmy Blue he spotted is a Walla Walla County record.
“At that point I was like, ‘OK, that’s probably a more notable sighting,'” Lindsey said.
It turns out that western pygmy blues have cropped up in this region from time to time, James said. In 2004, the first western dwarf blue was sighted just off the Washington side of the Columbia River.
However, they have never appeared in the numbers butterfly lovers are seeing this fall. Since Lindsey’s first report, butterfly watchers have around 30 other places noted where the butterflies were found, said James.
“Reports have come in en masse over the past four weeks. Interestingly, we now have locations along the rivers,” James said, including the Snake, Columbia, and Yakima rivers.
Reports of these burgeoning butterflies have come in from Walla Walla, the Tri-Cities and Klickitat County.
James noted that one of the largest populations is along a dirt road near Richland, Washington.
On a shoulder littered with noxious Russian thistles, better known as tumbleweeds, the western pygmy blue has dazzled entomologists and brought insect watchers from faraway towns to the banks of the Yakima River.
“Western pygmy blues love hot, dry places and conditions. They choose terrible places to live. Not pristine habitats like most butterflies where you have to go to the mountains or somewhere really nice to see them. To find the pygmy blue, just pick the worst piece of land you can find as long as there are the weeds they like,” James said.
At this point along Snively Road, James said he counted at least 190 butterflies during a 30-minute pollard walk, which is a method of systematically measuring butterflies. Most of the butterflies James counted were males, meaning a similar number of females are likely hiding nearby.
“It’s really an invasion,” James said. “I think what happened is that this addition to the range happened in July or August and nobody noticed.”
That likely means multiple generations grew in the area and continued to spread, James said. The lifespan of western dwarf blue is about three weeks, depending on the outside temperature.
There’s a chance this butterfly species will be helped by a changing climate, as its range can expand, unlike most butterflies, whose ranges will shrink with warmer summers and winters, James said.
“We know that each year it expands its range into areas where it cannot overwinter and comes back the next year. So I suspect that’s going to happen,” James said. “In the future, when our winters get a little warmer, they’ll probably survive. But I don’t think it’s that far yet.”
However, James said he plans to keep an eye out for the butterflies next spring.
Butterfly enthusiast Dan Dunphy, 60, traveled from Kent to the Snively Road to see the western pygmy blues on a field trip with the Washington Butterfly Association. The trip was the first time he saw the tiny insects.
“At first I thought I was just looking at flies. They were just small and looked black. They moved so fast,” Dunphy said.
Once he got used to seeing the butterflies, he made himself comfortable and used his binoculars to zoom in on the butterflies sitting there.
“Then I could take a step back and watch all the butterflies flitting around, doing their thing and living their lives,” Dunphy said.
As he watched, Dunphy said he observed the beauty of the tiny creatures. Perhaps ill-named, the western pygmy blues are more visible brown in color.
“To really see it in person: the color, the texture. They have shiny patches on their outer hind wings that look like little mirrors. Just dozens of little mirrors reflecting the light. A very stunning butterfly, even for such a small, small, small insect,” Dunphy said.
When viewed without binoculars, the butterflies have a slightly rusty color. However, the blue becomes more visible in macro lens photographs, said Jane Abel, a photographer who walks the Columbia River with her husband every day looking for butterflies.
On Snively Road, a tumbleweed seems to make a particularly attractive home for the western pygmy blue: a shrub just behind a lone porta potty.
“Here’s the magical tumbleweed behind the ACE porta potty,” Abel said. “There are several butterflies flying around the bottom of the tumbleweed. There are probably a dozen of them on this one plant.”
The tumbleweed is much larger than other Russian thistles nearby. The butterflies are likely to be attracted to the moisture and nectar of the tumbleweeds. But it’s not just that, James said. The males get nutrients from urine and other minerals and salts.
“The soil near Porta Potty could be rich in these minerals and salts and then elsewhere,” James said. “It just fits with the fact that this butterfly doesn’t really like pristine habitats. They choose the porta potty place to find the butterfly. Just sum it up really.”
Looking up the hill, next to the porta potty, which doesn’t smell at all, butterflies flutter around the healthy tumblewees.
“Look at them all,” said Abel.
As sandhill cranes flew overhead, Abel snapped some photos of butterflies on a mustard plant to better see the color differences, she said.
As long as the butterflies are here, Abel said, she’ll keep coming back to Snively Road.
“This is probably my new favorite place,” she said.