Residents report dazzling swarms of monarchs this fall

Troy Shantz Sarnia-Lambton has been aflutter with monarch butterflies in recent weeks and it’s a positive sign the migratory insect might just be on the rebound.

Troy Shantz

Sarnia-Lambton has been aflutter with monarch butterflies in recent weeks and it’s a positive sign the migratory insect might just be on the rebound.

Huge numbers of monarchs have been reported landing in bushes and backyards all over the city, with several residents sending The Journal remarkable photos.

Sharon Nethercott, an outdoor educator with the St. Clair Region Conservation Authority, said this fall’s southern migration has brought the greatest concentration of butterflies to Sarnia she’s ever seen.

She encountered clouds of them in Canatara Park on Sept. 14.

“It was magnificent,” she said “I believe there was easily 1,000.”

Monarch butterflies go through a multi-generational migration. It takes several generations of the species being born along the 5,000-kilometre route to make it from their winter home in Mexico north to Ontario.

But each fall, they head south again flying directly to the mountains of central Mexico, re-enacting one of the world’s longest insect migrations.

Researchers have noticed a significant decline in the number of monarch over the past two decades, making it a species of “special concern” in Ontario. That means it’s not endangered or threatened but is at risk of becoming so.

This fall’s resurgence is a very good sign, Nethercott said.

She credits a growing awareness about the need to preserve native milkweed, once classified as a noxious weed. Milkweeds are a favoured plant of monarchs and a vital food source for their hungry caterpillars.

If you want butterflies to keep coming back, plant milkweed and other native plants, she said.

“Things can be overwhelming when you think about the world as a whole,” Nethercott said.

“But when you just take care of your little patch in your own backyard you can really benefit a species. We’re seeing that with the monarchs.”