Editors note: A Previous version of this story stated the Frazer Homestead property was owned by the San Juan Preservation Trust. It is actually owned by the San Juan County Land Bank.
Although they gather the most attention, the Southern resident orcas aren’t the only endangered species residing in the Salish Sea. On San Juan Island, the tiny island marble butterfly struggles to survive in its final known location in the world.
“It seems we are the last stronghold of this butterfly,” Jenny Shrum told the audience during her free talk at the San Juan Island Public Library on June 12, titled “Fluttering across the Salish Sea.”
Many agencies, governmental, nonprofit and volunteer, have become involved for the sake of the species.
The San Juan Preservation Trust, San Juan County Land Bank as well as the National Park Service, have been planting the butterflies favorite plants, tumble mustard and field mustard, and Washington Department of Fish and Wildlife are proposing the marble be listed on the states endangered species list.
Shrum has worked with the National Park Service across the country to preserve larger charismatic creatures like wolverines. hawks and seals. Her current project, helping the marbled butterfly, led her into the insect world. She has been trying to better understand the last remaining population of the island marble butterflies, also known as euchloe ausonides insulanus.
Island marbles are a small- to medium-sized butterfly with a yellow-green marbled pattern on the lower side of the wings, giving the butterfly its name. The butterfly’s eyes are big and green. A close up look at the animal shows within that each eye contains many eyes, explained Shrum.
“They have a compound eye,” she said. “That matters, that’s how they see the world.”
How humans think the euchloe ausonides view the world is probably not accurate, Shrum noted, since people have single, not compound eyes. Yet, human beings must cross this divide to understand the butterfly, its wants and needs, if it is going to be saved.
There are only 200 of these butterflies remaining. Compared to the 76 Southern resident orcas, another struggling species, the butterfly population sounds high. However, Shrum said, there are a couple of key differences between the butterfly and the orca, besides one being a mammal and the other an insect.
Researchers have learned how to identify every killer whale, therefore the total population number is well known. It is nearly impossible to identify each individual butterfly, let alone compile a true count given how quickly they move around, so 200 is a rough estimate, she said. Its dwindling population shows that the insect is in dire straits. Should the butterfly go extinct, researchers believe the impact of losing another pollinator could be catastrophic for the island’s wildflowers.
Canadian archive record from Vancouver Island and the Gulf Islands indicate Island Marble Butterfly citings in those locations. No island marbles observations were recorded again, until 1998, when John Fleckenstein, Washington Department of Natural Resources zoologist recorded an unidentified white butterfly on the South end of San Juan Island.
Shrum said it’s possible the mysterious butterfly was here the whole time, quietly pollinating the island’s meadows, or perhaps it migrated from other unknown locations. No one knows for sure where it was, or what it was doing.
Fleckenstein’s observation led to several studies, which found multiple populations on Lopez and San Juan islands. Since the 2000s, however, the population has been contracting.
One issue is the favorite plants of the butterfly; pepperweed thrives around lagoons such as Jackals Lagoon, however, tumble and field mustard are considered weeds and often destroyed by landowners. Deer, on the other hand, find mustard delicious.
“Deer love mustard; it’s their preferred salad,” Shrum said, as the audience laughed. She added that the National Park Service has put fencing up to protect the host plants, however, that too causes problems.
“We noticed, for example, [the butterflies] sort of bounced along the outside of the fencing,” she explained, noting that bees often have the same reaction to fencing. As a result, park staff takes down the fence a few months each year, so adults butterflies have an easier time accessing the mustard, and put the fence back up the remainder of the year.
“It’s a lot of work [to fence and de-fense], but we think it saves enough of the plants to make it worthwhile,” Shrum said.
The lifespan of an adult island marble butterfly is only about six days — certainly, no longer than nine, Shrum explained. The best time to see them is April-June, peak flight season being mid-May.
“The best thing to do for the butterfly is to stay on existing trails as you never know where a cocoon may be over-wintering,” Shrum said.
Female island marbles can lay 30-40 eggs, she continued, typically on mustard or pepperweed flowers. Those eggs take between nine to 10 days to hatch. The eggs are the size of two-period punctuation marks side-by-side, and a distinctive salmon colored with ridges along the sides, according to Shrum.
The juvenile butterfly, a caterpillar, goes through five instar stages. Instar is the scientific term for each caterpillar phase. Each lasts approximately three to four days. Shrum explained. The last instar has three days extra to walk off its host plant, find alternative vegetation, and fully morph into a chrysalis, or cocoon.
Shrum also described the difficulties of morphing through each stage.
“Sometimes the head cap doesn’t come off as it molts,” she said. When that occurs, the caterpillar appears uncomfortable and won’t eat much. Shrum noted caterpillars have been seen actively attempting to knock off the cap.
One of the fascinating things about this butterfly is that it spends the next 10.5 months chilling in the cocoon. Keep in mind the creature only lives one year.
Currently, the only known populations have been in American Camp and Eagle Cove Shrum noted. However, toward the end of May one female was observed on the San Juan County Land Bank property, Frazer Homestead, located not far from American Camp.
Craig Canine, communication director of the trust, said that the butterfly was seen by naturalist Susan Vernon. Photographs later showed the butterfly was a female.
“[The butterfly] was nicknamed Amelia after another adventurous flier,” Canine said.
Eggs were later found on a mustard plant that Kathleen Foley, trust stewardship manager, and trust staff had been carefully cultivating on the property. According to Canine, those eggs have already hatched and are working through their caterpillar stages.
“It’s the first notable expansion in nearly a decade and a hopeful step towards the recovery of the species,” Shrum told the Journal.
There are a couple of things landowners and the general public can do to help the species, one being not disturbing its host plants, the other being careful to stay on trails while walking through butterfly habitat.
“You wouldn’t think a butterfly would be such a complicated thing,” Shrum said.
To learn more about the island marble butterfly and current conservation efforts, visit www.nps.gov/sajh/learn/nature/island-marble-butterfly.htm, for the National Park Service, or sjpt.org/what-we-do/care-for-land/stewardship/stewardship-projects/island-marble-butterfly-project/ for the San Juan Preservation Trust. For information on WDFW endangered species listing, visit www.fws.gov/wafwo.