05/15/2026
For 90 years, nobody knew she was here. 🦋
The endangered Island Marble butterfly was last seen in 1908 on a Canadian island. She was thought to be extinct. But in 1998, a biologist spotted her while surveying the coastal prairies of San Juan Island. Since her rediscovery, many organizations have stepped in to protect her.
Today, she can only be found in one place on earth: the south end of San Juan Island, at American Camp.
She is a delicate beauty, measuring 1.75 inches wing tip to wing tip. Creamy white wings, black-patterned wingtips, and a fine black rectangle mid-wing. And on her underwings, you'll find the greenish-yellow marbled pattern she's named for.
When the Island Marble's habitat was altered since European occupation, and coastal storms caused more damage, she didn't vanish. Every stage of her life cycle depends on a host plant for laying eggs and feeding caterpillars. She adapted and started using Field Mustard, a plant that paints San Juan's agricultural areas annually.
SJPT has been supporting her since 2015. We provide both native host plants and mustard in our protected habitat plots. Over the past decade, many staff, volunteers, and members have helped turn the soil into suitable habitat. Today, a dedicated group of volunteers we call Habitat Helpers, keep watch in real time, alerting us to any issues that might affect her chances of survival.
Today is Endangered Species Day. The Island Marble is a reminder that the quiet work of many people is what gives a species a fighting chance.
Want to be a part of it? Head to our website to learn about our Habitat Helper Program. (Link in the comments.)
