A friendly debate about migration and raising caterpillars

Recently, I got into a debate on Facebook with a rando stranger. That’s always fun, eh? It did make me realize there is a lot of confusion out there. Even the terminology is inconsistent! So let’s get that out of the way first:

• Monarch: can refer to caterpillars or adult butterflies. Usually contextual clues are used to differentiate.
• Raising/rearing: these interchangeable terms are a reference to any person, group, or corporation that is keeping caterpillars. How the caterpillars are obtained and the methods used to keep them alive are a secondary distinction. Whether you’re an old lady with curlers in her hair or a large corporation selling to schools, a five year old boy or a bachelor giving them to his friends, if you have caterpillars in a pop-up tent or a Mason jar or a factory or anywhere in between, if you have altered conditions in any way from Mother Nature, then you are raising/rearing monarchs.
• Captive Rearing: technically the same as rearing/raising above, but in actual practice is typically in reference to a breeder.
• Hobbyist/enthusiast: (interchangeable) A person/family raising caterpillars born in the wild at their home (either indoors or out), and releasing adult butterflies back into the wild. It’s probably you, dear Reader, as I highly doubt my blog is big enough to have reached a large-scale corporation.
• Breeder: A person or business that that keeps adult butterflies in captivity on a large scale, and sells the eggs and caterpillars for profit (for example, to a school for classroom learning).

Okay, back to the point: my Facebook debate was regarding migration. It was a friendly conversation, so I figured it deserved a F.R.I.E.N.D.S.’ly response.

There have been many articles shared within the hobbyist community with some version of this headline: “Monarchs raised in captivity lose ability to migrate.”

The debate I got into began with an enthusiast’s comment: “I am only raising the caterpillars and not the butterflies. The day they become butterflies, they are set free in my back yard so I am assuming this does not refer to me.”

Which made my stickler for accuracy, “I love words,” English Major’s head POP OFF. I tried so hard to just let it go, but it just drove me insane. I couldn’t! How could I? I’m my mother’s daughter, after all. Of course, I had to speak up.

For simplicity, I’ll refer to commenter as a woman named Janice (yes, the first of many Friends references and attempts at cleverness. Forgive me). After reading her comment, it really felt like this rando Facebook stranger that I’ve nicknamed Janice also symbolizes everything that is wrong with the world: An ignorant attitude with no desire to learn, zero sense of responsibility, and a dismissive “I didn’t know so it’s not my fault,” mentality.

“I am only raising the caterpillars and not the butterflies”?! Oh. My. Gosh. What does that even mean! You can’t “raise” butterflies… They’re all adults! They don’t grow. You can keep them in captivity or release them, but the raising has nothing to do with adult butterflies. Yes, the @#&$ article refers to you, Janice! It refers to all of us! The only two people that are exempt from the article are God and Mother Nature.

“The day they become butterflies, they are set free in my back yard,” Janice continued. That just means you’re not keeping adults in captivity; that you’re not breeding monarch butterflies. But if you have 1 pop-up tent or 15, or whether you bring caterpillars in from the milkweed in your back yard, down the road, or a field two towns over. It makes no difference if you are keeping them in your home, your New York apartment over Central Perk, on your porch, or putting a tomato cage around a milkweed plant and throwing mesh over it… Those details don’t matter as far as terminology goes. When a caterpillar is in an altered environment—even if the alteration is just a lack of predators—if the caterpillar is unable to leave that is pretty much the definition of captivity. Whether the caterpillar would choose to stay or not is irrelevant… It’s still in captivity. It applies to you, Janice!

All that said and liberally punctuated with exclamation points, until recently the bulk of those articles didn’t really apply to hobbyists. Let’s take a moment to giggle together at how fired up I was over a “moo” point. Previously, studies did not take into account an important distinction between a hobbyist and a breeder: the source of the caterpillars which will turn into the butterfly being studied.

A hobbyist is almost certainly getting their caterpillars from eggs that were laid by a monarch butterfly living in the wild. A breeder is almost certainly raising caterpillars whose parents were not only kept in captivity, but most likely born in captivity too. For many generations. For more information about these studies, check out a video by Mr Lund Science here.

The studies were performed on wild versus bred butterflies, which means the article professing that “captive monarchs can’t migrate” is leaving out the average hobbyist like myself, Janice, and undoubtedly you too. Shall I call you Monica or Joey?

The studies concluded that butterflies who have been in captivity for generations were less likely to orient south. Therefore, as far as enthusiasts were concerned, the entire article was “like a cow’s opinion. It doesn’t matter.” Hobbyists proclaimed that they have been raising caterpillars indoors for some time now, and their tagged adults were showing up in Mexico. It seemed like all the evidence was pointing to the same conclusion: the studies only apply to large-scale facilities keeping monarchs in captivity for generations.

Skip forward to August 2020: some researchers started looking a little closer at the data, and now the rate of success has been put into the spotlight. Instead of taking it at face value that tagged butterflies are showing up in Mexico, now researchers want to know who they are, where they come from, and what conditions they lived in while developing: “… there are two published and widely cited studies suggesting that reared monarchs do not orient properly or are too small or weak to reach Mexico. While that may apply to some reared monarchs, the rate of recovery of reared monarchs in Mexico suggests that the outcome could be improved if we developed a better understanding of the rearing and other conditions that lead to the highest rates of success.” (Monarch Watch)(emphasis mine)

Again, thanks to tagging we know absolutely there are caterpillars raised by hobbyists and released as adult butterflies that are making it to Mexico. However, the rate of success depends on a multitude of factors that require further study. Even though “… tagging records indicate that thousands of reared, tagged and released monarchs arrive at the overwintering sites in Mexico and survive through the winter, it is also clear that the likelihood of reaching Mexico is lower for reared monarchs. We want to know why. We need to sort out why some people who rear, tag and release have much higher recovery rates than others.” (Monarch Watch)(emphasis mine)

Therefore, new studies are being performed and published which are taking hobbyists into account. But, since there is such a variety in the conditions (indoors vs outdoors, plastic cup versus mesh cage, and so forth), it’s as complicated as whether or not Ross and Rachel were on a break when you try to answer the question, “Can they migrate or not?”

One such new study, “published in Proceedings of the Royal Society B on August 5, 2020, had two components: one looked more closely at the flight behaviors of individual commercially bred monarchs by tracking their flights repeatedly, and the other at the effects of natural sunlight exposure on the migration behavior of wild-bred monarch butterflies.” (phys.org)(emphasis mine)

More from that article: “To further pick apart the cues that trigger migration, the researchers opted to raise the wild monarchs in a greenhouse, where the butterflies were exposed to true sunlight throughout the day, as well as raising the insects in the lab near a south-facing window and in a large outdoor cage.

To their surprise, the natural light wasn’t enough to trigger the appropriate orienting behavior. Compared to the monarch butterflies raised in the outdoor cages, the ones raised in the greenhouse were worse at flying south.” (phys.org)(emphasis mine)

And finally, the researchers are asking: “Is it the sunlight, is it the location of the sun in the sky, is it a change in the plants or in the temperature? Is one of those cues the most critical, or is it a combination? Is there a critical period during the monarch’s life cycle for these cues to have the right effect? We just don’t know.” (phys.org)(emphasis mine)

It turns out the issue was much more complex than it seemed at first glance. Hobbyists should start paying more attention to these studies, because to all the Janices out there: it does refer to us!

Hobbyists can help increase data by filling out this survey for Monarch Watch and providing details about your set-up (click here).

So what’s the take away?

Please, to the best of your ability, keep conditions for your captive monarch caterpillars as natural as possible. In my opinion, based on what I’ve read, lighting and temperature seem to be the most important factors at this time. For that reason, based on what I’ve read, my official opinion at this time is that an outdoor fine mesh enclosure out of direct sunlight is best practice.

VERY IMPORTANT: hobbyists should not read this as a call to arms, nor an invitation for a witch hunt! When looking at the big picture, I refuse to believe that someone who found a couple caterpillars in their garden and took them inside their house to watch and protect has done anything wrong. Sure, we can gently suggest more natural conditions. We can promote education and guide them to good resources. But these people—including you, Janice!—are NOT the problem. They are trying very hard to make a difference and monarchs need people like in their corner.