Attention, all who have been raising monarch butterflies indoors — and I know there are lots of you — current research concludes that hatching indoors disrupts the butterflies' ability to migrate.
As someone who has been raising monarchs for more than 25 years, I find this sad.
I always thought I was doing something good. I always thought this practice was a way to bolster wild populations, to make sure that the eggs and caterpillars I saw outside on milkweeds actually turned into butterflies and weren't killed by predators or whatever else lurks out there.
The negative affects of raising butterflies in captivity came to my attention after our Aug. 23 monarch report in Home & Garden and a subsequent email from a researcher in Canada who pointed me to research at the University of Chicago.
Marcus Kronforst, PhD and associate professor in the university's department of ecology and evolution, has led studies comparing migration of outdoor- and indoor-raised monarchs.
For the study, he used butterflies raised by a company that breeds stocks of the insect year-round to sell to weddings, festivals and classrooms. (I didn't know such companies existed.) What he found is that instead of heading south, the mail-order insects flew in random directions and eventually died.
This is important because it is the migratory aspect that we're trying to preserve. We don't want monarch butterflies to simply exist, we want them to keep the instincts that propel them south to Mexico for the winter and north to the United States for the summer. It is one of nature's greatest spectacles.
Kronforst hates to tell people not to raise monarchs because he knows this creates a love of the insect, but he now believes that to preserve the migratory instinct, monarchs need to be raised in conditions that are as much like the outdoors as possible.
This means actually BEING outside.
He suggests putting the eggs and caterpillars in mesh cages with plastic or cloth on the top to protect them from sun and rain.
"Overall, the results (of research) indicate to us that the butterflies need natural outdoor conditions in order to develop into migratory butterflies," he wrote to me in an email.
"It is hard to know how natural is natural enough. I suspect a screened porch is okay. I agree that it is good to avoid direct sunlight. But our experiments show that sunlight filtered through glass is not sufficient.
"The goal is produce as natural an environment as possible while still protecting the insects from predators, parasites, sun, wind, rain, etc."
Even raising them indoors next to a window or in a greenhouse did not allow them to develop into migratory insects, Kronforst said.
I have always raised monarchs in glass canning jars with holes poked in the lids, set on a shelf inside my home. I see now this is NOT the way to do it.
And there's more.
Even following Kronforst's advice of an outdoor setting isn't fool-proof because of factors we don't yet know or understand about migratory cues. There are two critical parts to making a migratory insect, Kronforst explained: they have to have the correct genetics, and they have to receive the right environmental cues.
"We thought we knew those cues, but our experiment suggests we don't totally understand them," he said in a 2019 article in The Atlantic. Perhaps, aside from day length and temperature, the butterflies are also responding to the angle of the sun, or the diminishing quality of the milkweed plants they eat.
So does that mean that by my feeding them nice fresh milkweed leaves every day they aren't getting the right cues, even if they are outside?
"While many people hope that captive rearing is helping a declining population, the cumulative data available suggest that captive breeding of monarchs has negative consequences for migration behavior and that monarchs reared indoors are not as well equipped to survive migration as those left in the wild," he concluded in his latest research paper published in July.
"We also know that rearing monarchs at home and in educational settings inspires new generations of conservationists, nature-lovers and scientists.
"For those who love rearing monarchs, we advise the following: rear caterpillars individually in clean enclosures, rear outdoors when possible (especially in late summer and autumn), limit the total number reared (and) avoid purchasing (that is, collect in the wild).
Note: Janet Moline of Rock Island uses mesh laundry baskets from Ikea as her containers. If you "google" "mesh laundry baskets" you will find many options in the $10 and up range.
Kronforst also suggests we participate in citizen-science projects.
"The nonprofit Monarch Joint Venture lists links to many on-going citizen science studies which have contributed vastly to our understanding on monarch biology," he writes.
"Finally, if we want to ensure the future of migratory monarch populations, we must promote longer-term solutions, such as protecting and restoring habitat and addressing climate change."
So there you have it. To preserve migrating monarchs — and any wild creature — we need to do the hard work of creating and preserving habitat and pushing for legislation or whatever is needed to limit the effects of climate change.
Catch the latest in Opinion
Get opinion pieces, letters and editorials sent directly to your inbox weekly!