The number of monarch butterflies overwintering in California has fluctuated dramatically over the past several years. But even with promising numbers in 2021, the population is considerably reduced from the 1980s when millions overwintered in California. (Jeff Stefan/iStock)
When a Bay Curious listener named Ellea, who lives in Richmond, heard the news that so few Western monarch butterflies were counted in California, she wanted to help. She planted some milkweed — the only plant that Western monarch caterpillars eat — and tried to raise some monarchs to release into the wild.
But things didn’t go as planned. Only about half her caterpillars matured to adult butterflies.
“I was devastated by that,” she said.
And her milkweed wasn’t doing so well either. One plant seemed to disappear altogether.
“Monarch butterflies are plummeting toward extinction. This is my first year trying to raise them,” Ellea wrote to Bay Curious. “I’m shocked at the difficulties in getting, planting and protecting native milkweeds. Why is it so hard?”
Terry Smith of the Pollinator Posse, an Oakland-based nonprofit that educates and trains people to help pollinators like the Western monarch, said she heard from a lot of people who started to rear monarchs in 2021.
But as well intentioned as those efforts are, raising butterflies without a permit is actually illegal in California, the same as it would be for any wild animal.
“People thought that because they were insects, they didn’t count,” said Tora Rocha, Smith’s co-founder of the Pollinator Posse.
Research shows that when humans help monarchs through the delicate metamorphosis from egg to adult butterfly, it can actually hurt the species. It produces butterflies less likely to survive migration and contributes to the spread of Ophryocystis elektroscirrha (commonly known as “OE”), a parasite that kills monarchs.
You’re “raising them in a false climate,” said Rocha.
How to plant pollinator-friendly gardens
But there’s good news for anyone interested in helping monarchs: You can take plenty of other actions, whatever your skill or commitment level.
“Planting habitat, reducing pesticide use in your community or pressuring elected officials at all levels of government to enact real solutions to climate change — these things are going to have a big impact on monarchs and all of the other pollinator species who are also in need of conservation help,” said Laws from the Xerces Society.
Rocha said that you don’t need a big garden to make an impact. Even one or two nectar plants on a stoop or balcony helps.
But if you’re planning to grow milkweed, be sure to find some that’s native to California. Native milkweed goes dormant in the winter, which reinforces the monarch’s migration pattern. But tropical milkweed, often sold at plant nurseries, can increase the spread of OE, that deadly parasite that kills monarchs.
There’s a lot of information about milkweed varieties on the internet — it can get overwhelming. One good resource is this fact-sheet from the Xerces Society, which recommends types of milkweeds to plant and types to avoid.
Like a lot of gardening, finding a place where your native milkweed will grow requires some trial and error, and patience, said Rocha. “They want sun, they want heat,” said Rocha. “Things that go dormant take a little longer to establish.”
Some growers make the mistake of thinking that their native milkweed has died when, really, it’s doing what it’s supposed to: taking a winter break.
That said, native milkweed can sometimes be hard to find. It’s in high demand, and garden clubs and plant societies often sell out.
But there are plenty of other plants you can grow to support the Western monarch.
While it’s true that milkweed is essential for breeding and for feeding caterpillars, the monarchs’ main activity in the Bay Area is overwintering, when the butterfly enters a stage of reproductive diapause.
“They need to keep their fat stores up to survive the winter, and that means they have to stay alive for four months,” said Rocha. “So they need to get nectar, and [in the Bay Area] we don’t have a lot of nectar in the winter.”
Angela Laws and Tora Rocha say asking about pesticide use when you buy plants sends an important message.
“Because if people start hearing from many of their customers that this is something that they want, I feel like that will lead to big change,” said Laws. “So just asking, I feel like it’s really powerful.”
Rocha finds it particularly frustrating that nurseries use neonicotinoids and other pesticides on plants they advertise as pollinator-friendly.
“Nurseries use it because they only have to spray it once and it’s just cheap,” she said.
“Ask the nurseries the hard questions,” said Rocha. “Because they’ll tell us they have to spray because no one wants to buy a plant with aphids. Well, we want to see aphids because then we know it hasn’t been sprayed.”
Citizen scientists observe and report monarch populations
Rocha said the other big thing you can do to help Western monarchs is count them.
“We need to look into more observation. We just don’t have the answers,” said Rocha.
This is especially important given that some monarchs are staying year-round in places they used to use only for overwintering.
“Now it seems like there’s a year-round population that just stays in the Bay Area all year and doesn’t migrate,” said Laws. “We don’t know much about that population yet. What’s driving it? We don’t know if some of those individuals do migrate, and we also don’t know how sustainable that is.”
In the world of butterflies, there’s a tradition of citizen scientists contributing in major ways.
“Scientists didn’t know where monarchs went in the winter,” said Rocha. “It was citizen scientists that tagged them and found them in Mexico.”
Help one pollinator, you help them all
As much work as Rocha has done to help monarchs, it was bees that first got her involved in protecting pollinators. She sees the monarch as a flashy ambassador that draws people into caring about the plight of pollinators in general. And that’s fine by her.
“Once you help one pollinator, you’re really helping them all,” she said.
A lot of the nectar plants that support monarchs support other species, too. Similarly, limiting the monarchs’ exposure to pesticides means other insects will be exposed less.
“We can’t let the monarchs go, because it means we’re failing the rest of the pollinators,” said Rocha. “If we’re willing to let an iconic species die, then we’ve really messed up.”
Don’t call it a comeback … yet
The 200,000 plus monarchs spotted overwintering across California during 2021’s census have certainly renewed Rocha’s hope.
But she knows that a good year does not signal a full recovery.
“Insect populations tend to bounce around a lot,” said Laws. “They can go really high and really low.”
The 2021 numbers are coming after multiple years of very low numbers — and remember, there were millions of monarchs in California as recently as the 1980s. In that context, 200,000 doesn’t seem like such a victory. And the Western monarch still lacks protection at the federal and state level.
Perhaps this year’s showing is the monarch’s way of telling humans not to give up on them, that given adequate habitat and protection, they can thrive once again.