Doreen Nicoll is a true hero of the little guy.

The Burlington resident has successfully lobbied the city to stop killing milkweed, because the plant is the only one in Canada on which the endangered monarch butterfly can lay its eggs.

It's a fight that started all because one of her neighbours complained about her lawn, she says, which is a "naturalized garden" full of a wide assortment of plants instead of grass.

Nicoll, who lives in north Burlington just off of Walkers Line, came home on June 29 to find a bylaw notice on her front door. It told her to get rid of the milkweed growing on her lawn.

"I was really disappointed. I was kind of sad," she told CBC News. "A little bit angry, I'll admit that too."

The monarchs are in trouble. - Doreen Nicoll

Neighbour troubles aside, she was most worried about what the butterflies who lay eggs in her garden would do.

According to the World Wildlife Fund (WWF), the monarch butterfly is considered an endangered species, and milkweed is vital to its life cycle.

"This is the only plant that they'll lay their eggs on," Nicoll said. "And the caterpillars eat the leaves, and then they form chrysalis and then they take off."

A dramatic decrease in butterfly populations

The monarch is one of the most recognizable species of butterfly, with distinctive orange, black and white markings on its wings.

Each fall, these butterflies set out on a 5,000-kilometre journey from southern Canada through the U.S. to their wintering sites in the mountain forests of Mexico. According to the WWF, it's one of the world's longest insect migrations.

The organization says that over the last two decades, there has been a dramatic decrease of the area occupied by monarchs on their wintering grounds, from almost 18.2 hectares of forest at their peak in 1996 to just 2.5 hectares in 2017.

Nicoll says the milkweed in her yard hosts butterflies each year. (Doreen Nicoll)

The WWF says the butterflies are threatened by deforestation of wintering forests in Mexico, disruptions to their migration caused by climate change, and the loss of native plants — particularly milkweed — along their migratory corridors.

All this to say, the milkweed growing in Nicoll's garden seemed more important to her than a neighbour's perceived eyesore.

The province once considered milkweed a noxious weed under the Weed Control Act. Nicoll says it was originally banned because milkweed eaten by dairy cows caused their milk to taste slightly sour.

"It's actually a really pretty plant," she said.

The province dropped milkweed from its noxious weed designation in 2014, Nicoll learned, but Burlington never followed suit. She even started hearing from friends and associates that they were allowed to have the plants in cities as nearby as neighbouring Oakville.

"Then I found out that the city of Burlington gives the plants and the seeds away for free through the parks and rec," she said. "It was confusing they were giving it out for free and telling me to rip mine out."

Citywide changes

So she started making calls to the city and lobbying for changes to the bylaw. She says she spoke with councillor (and mayoral candidate) Marianne Meed Ward, and at the end of last week, got an email from Mayor Rick Goldring.

"It's clear to me that there was no good reason why we should be prohibiting the planting and growing of milkweeds, especially when they have such a crucial role in our natural habitat," Goldring wrote in his email.

Doreen Nicoll has been growing a "naturalized" garden in Burlington for 16 years. (Doreen Nicoll)

"After consulting with our staff, a decision was made that as of today ... our bylaw enforcement staff will not be enforcing the removal of milkweed from properties, and come September, we will be removing milkweed from the list of noxious weeds from our Lot Maintenance Bylaw.

"It's evident that our bylaw was outdated and changes were needed to accommodate the evolving climate we face today."

Nicoll said she was ecstatic that the city had decided to take such immediate action, because these butterflies need all the help they can get.

"The monarchs are in trouble," she said.

adam.carter@cbc.ca