An Island Marble butterfly feeding on field mustard at American Camp | Photo: Jeff Brennan

The rare and wonderful island marble butterfly is on the wing. Its field season has begun. With likely fewer than 200 marbles in existence and an adult lifespan often lasting 10 days or less, the butterfly’s opportunities to breed are limited and intense. Time is of the essence to support this enigmatic beauty and to help it find safe havens here on San Juan Island.

The Preservation Trust’s “suitable habitat patches” (SHPs) at Frazer Homestead and Sundstrom Farm Preserve on San Juan Island continue to bloom, acting as bright yellow beacons to lure island marbles to these safe zones.

We watch, wait, and monitor each bloom. We hold our breath as each white butterfly that comes into view possibly holds the promise of island marble.

The Preservation Trust looks forward to expanding its current patch program across the island, but that will take time. If you would like to be involved now, here’s what you can do:

Go to the SJPT website and familiarize yourself with island marble, its habitat and host plants, including field mustard (Brassica rapa).

Brassica rapa (field mustard) plants | Photo: Jeff Brennan

• Check your garden or property (both in town and across San Juan Island) for field mustard. If it is present, look for white butterflies nectaring (feeding) on the blooms. The butterflies you see will likely be cabbage whites, but they could be island marbles. Look closely. Check the details. Be especially alert for the yellow, gold, and white pattern on the underside of the butterfly’s wings. If you see this marbling, contact SJPT Stewardship Manager Kathleen Foley at and we will investigate.

Here is an identification guide, courtesy of the Washington Department of Wildlife.

Saving endangered wildlife requires all hands on deck. The Preservation Trust encourages islanders to get actively involved in saving this rare insect. You may already have a safe zone for island marble on your land. That would be an important discovery and a great help to the butterfly. Island Marble calls the San Juans home, and so do we. Let’s all work together to ensure that this special butterfly continues to have a place in our midst.

– Susan Vernon