A Weed Patch in this Ontario City Turned Out to Be a Magnet for a Treasured Species

A milkweed patch sprouted at the Greater Sudbury Wastewater Treatment Plant. The team and community groups turned it into a haven for monarch butterflies.

A Weed Patch in this Ontario City Turned Out to Be a Magnet for a Treasured Species

Michael Loken, manager of wastewater treatment for the City of Sudbury, overlooks the milkweed patch that has grown near the facility’s chlorine contact chamber.

During summer, hundreds of migrating monarch butterflies are attracted to the Greater Sudbury Wastewater Treatment Plant.

A nearly half-acre milkweed patch on the back side of the chlorine contact chamber and near its receiving water, Junction Creek, provides a habitat for the butterflies’ life cycle.

Michael Loken, manager of wastewater treatment for Greater Sudbury, in Ontario, says the milkweed started showing up at the plant (42 mgd/design) five to 10 years ago. “No one really can pinpoint the exact time, but it’s interesting and we have been trying to encourage it to grow,” says Loken.

Since then, the plant staff, along with community interest groups, has nurtured the monarch breeding area and expanded it to others. The motive force behind monarch habitat preservation at the plant and along Junction Creek is Dr. Joe Shorthouse, a retired professor of entomology at Laurentian University.  “Joe first identified the growth of milkweed at our plant and encouraged us to just let it grow,” says Loken.

Let it grow

Among community groups that have worked with the plant is the Junction Creek Stewardship Committee, a nonprofit volunteer organization that focuses on improving the large urban waterway through research and monitoring, restoration projects and education. The group promotes the creek’s ecological benefits and works to connect the community with it.

“The stewardship committee looks after the creek, and they suggested we let the milkweed grow, and it grew quickly,” says Loken. “It likes the sandy soil, and it stabilizes the creek bed and adds to the aesthetics.”

Loken is manager of all 10 of Greater Sudbury’s treatment facilities, plus two lagoons. Plant operators have been instructed by Dr. Shorthouse on how to properly transplant the milkweed. “We have actually transplanted milkweed to some of our other facilities,” says Loken. “Some of them have been successful, and some have failed.”

The life cycle

Once the transplant is established, no maintenance is required. The milkweed is noninvasive and does not damage tanks or equipment. “It’s not like a willow tree that deeply buries its roots to find water, so we don’t see any issues with it up against concrete or any of our tanks,” Loken says.

The monarchs arrive in early spring, find milkweed to feed on, lay their eggs and then die almost immediately. During a six-week cycle, caterpillars hatch from the eggs, feed on the milkweed leaves until mature, and then form chrysalises, from which the butterflies emerge. Depending on the weather, one to three generations of monarchs live in Sudbury between May and September.

When the weather turns cold, the last generation migrates to the mountains west of Mexico City and can live six to eight months. In early spring, they head back to Greater Sudbury, but with two or three stops along the way, at each stop each repeating the life cycle.

How the monarchs navigate to their migratory destinations is unknown. Each year, Dr. Shorthouse applies identifying tags to the wings of many before their trip south. “Joe has tagged hundreds and hundreds of monarchs and wants to find one that was tagged here at our wastewater plant,” says Loken. “He thinks that would be the most amazing story.” 

Taking tours

Because the milkweed patch at the plant is not readily visible from outside the plant, most residents see it only during plant tours. During pre-COVID-19 times, tours were encouraged and well attended, especially among school children.

“We get lots of high school and college students who learn about the facility and how we are part of the community,” Loken says. “It’s also nice to show them that we’re doing things outside the scope of wastewater treatment, that we are doing things that are encouraging biodiversity and supporting this beautiful species that is at risk.”

Providing for and promoting the milkweed at the plant has proved to be good for public relations, too. Dr. Shorthouse wrote an article about the efforts of operators and staff that was published in an August 2019 edition of the Sudbury Star newspaper.

The milkweed patch lets people know that the plant is not just another industrial site: “Milkweed has a pleasant smell and helps with any odor associated with the facility. That makes us a little more amenable to our neighbors. The monarch has a fantastic life cycle, and encouraging that life cycle to continue is really wonderful.”   



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