Monarchs Found the Park Milkweed!
We were very excited when an adult Monarch was spotted visiting milkweed at Rasor Park in the summer of 2021, and again in 2022. But we were positively thrilled to find tiny Monarch eggs and caterpillars on some of the milkweed plants in 2022, 2023 and 2024!
Monarch caterpillars have high mortality in the wild, so we collected and reared them under mesh to protect them from predators. A month later, we released the newly emerged butterflies back in the park. We are so gratified that these now very rare Monarch visitors found our milkweed, and we were able to assist them in successful reproduction and release back to the wild.
Check out the images in the gallery above (click for larger view)—and help us keep a look out for Monarchs in the park this summer!
Sadly, we did not have any sightings in 2025.
Rasor Park Milkweed Restoration
Thank You, Milkweed Volunteers!
Special thanks to everyone who has helped prepare ground, plant, water and weed around showy milkweed plants nearly every year since 2016.
Milkweed is a hardy native plant well adapted to summer drought conditions here in the Willamette Valley. However, it takes some extra TLC in early stages to get it to survive and thrive in an environment as rough and dry as the park. Indeed, it has taken a village to get this far—with folks growing out two-year-old milkweed starts, laying shade cloth to kill grass, carefully planting the delicate bare-root plants into deep holes, setting up a watering barrel, and individuals or teams descending on the park regularly all summer after each new round of planting, hauling water jugs on wagons or with bike trailers. Young children and dogs have helped, too!
There are now multiple good-sized milkweed patches in the park. The milkweed plants will continue to spread by seeds or rhizomes on their own if we help keep them from being choked out by invasive grasses and weeds. Let us know if you can help with watering baby milkweed in the summer!
Frank & Joy Thomson, Stephen Amy, Maradee Girt, Peter James, Becky Riley, James Hershiser, Clare Strawn, Joe Castino, Newt Loken, Deb Bernhard & Flagg, Liz Van Buren, Nancy Boyd, Jolene Siemsen, Lori Howard, Asha Jenny Ulrich, Hafiz Leland, Robert Taube, Sydney Kissinger, Bruce Eveland, Juliet Thompson, Julie Hulme, Misty White, Tom Kreider and Paula Gordinier, Hassouna and Margo, and everyone else who has pitched in!
Thank You!
Milkweed for Monarchs
Monarchs in the Willamette Valley
Beautiful Monarch butterflies were once common summer visitors to the southern Willamette Valley. Historically they overwintered in forested groves on the California coast, and made a spectacular annual migration north through Oregon and Eastern Washington for the summer breeding season.
Western Monarchs are in Trouble
Overwintering populations of Monarchs in California have declined by over 95% since the 1980s. From 2018 to 2020, the western migration collapsed to new lows and scientists believed they were on the verge of extinction. Fortunately, there was a population rebound from 2021-2023, but it was followed by another drastic drop in 2024. There are multiple factors that are thought to be driving the precipitous decline, including habitat loss, pesticides, and climate change.
Monarchs Need Milkweed & Nectar
Monarchs require milkweed to reproduce—it is the only plant they will lay their eggs on, and that their caterpillars will eat. (Adult Monarchs also require other nectar flowers throughout their lifespan.) Milkweed and other native nectar flowers were once common in the Willamette Valley, but now are rare as nearly all the native prairie has been plowed and paved to make way for farms and gardens, housing, and roads.
Bringing Back Milkweed—and Monarchs?
We are in the midst of a multi-year effort, started in 2016, to re-introduce showy milkweed (and other native prairie plants) to Rasor Park to help improve breeding and migration habitat for Monarchs along the Willamette River Greenway and migration corridor.
