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Wanted: Monarch butterflies, last seen heading south

monarchPROSSER, Wash.—Researchers at Washington State University are calling upon the public throughout the western U.S. to report sightings of tagged monarch butterflies that are making their way from Washington State to as far south as Mexico.

WSU entomologist David James has released close to 1,500 butterflies so far with plans to release up to 1,000 more by early October. Each butterfly has a small circular sticker attached to a wing. He wants to know where butterflies from the Pacific Northwest go for overwintering.

“We are beginning to get reports of people seeing them but we’d like to alert more people to be on the watch for them in Washington, Oregon, Idaho, Nevada, Utah and Arizona,” James said.

Tagged Monarch 004 copy
A tagged Monarch

The butterflies released from Washington generally head to California but James believes they may get all the way to Mexico based on previous reported sightings of butterflies tagged with his email address. In 2012 one of James’ butterflies was reported from Utah, off course from California destinations but along the way to Mexico.

The insects head south to spend winter in warmer areas before making a return migration in spring. The tagged butterflies will live for up to 8 months.

Monarchs rely on milkweed plants for laying their eggs and providing food for their young. The larvae, or caterpillars, feed on the leaves of the milkweed plants until they turn into chrysalids, later emerging as the familiar orange and black butterfly.

“As well as providing potential data points, these releases are making a significant contribution to the conservation of this American icon,” James said.

In the last 20 years, monarch butterfly populations are thought to have declined by more than 90 percent. This is due to loss of habitat. The application of herbicides is thought to have drastically reduced the amount of milkweed available to monarchs in Midwestern corn and soybean fields.

“We also have a milkweed problem in western U.S. too with road authorities in California and Oregon in particular routinely spraying most roadside vegetation including milkweed,” James said.

The Center for Biological Diversity, Center for Food Safety, the Xerces Society and monarch scientist Dr. Lincoln Brower of Sweet Briar College filed a legal petition to the U.S. Fish and Wildlife Service seeking Endangered Species Act protection for monarch butterflies in late August.

With the help of inmates at the Walla Walla Penitentiary who help rear, tag and release the butterflies, James and the butterfly enthusiasts who spot the colorful creatures are helping to solve a butterfly mystery.

To learn more about James’ work with monarch butterflies watch this video and read this article

Report sightings to and visit the Monarch Butterflies in the Pacific Northwest Facebook page for updates:


Sylvia Kantor, CAHNRS Communications


Source contact:

David James, WSU Associate Professor of Entomology



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