Good Growing

In this episode of the Good Growing Podcast, horticulture educator Chris Enroth from University of Illinois Extension explores the adversaries of the monarch butterfly, including the controversial practice of captive rearing.

Although we do not recommend captive rearing, there may be times when it is wanted for educational purposes. Can it be done responsibly? Chris shares best practices for raising monarch caterpillars indoors. Instead of captive rearing, support habitat conservation efforts! Learn how programs like Monarch Waystations and pollinator gardens can help restore critical habitat.

Watch us on YouTube https://youtu.be/Yfzxnvpco0M

00:32 The dangers encountered by monarch butterflies
   02:07 Predators!
   02:17 Disease!
03:18 A historic shift in habitat for monarch butterflies
04:04 Introducing the concept of captive rearing of monarch butterflies
07:17 Why captive rearing is not recommended
   07:27 A loss of fitness
   09:21 Artificially overpopulating an area with monarch butterflies
10:38 If you are STILL going to captive rear monarch butterflies, here are some tips.
   11:44 What to feed your monarch caterpillars (cats)
   14:21 What type of container to use
   14:57 Placement of rearing cage
   15:14 Check and clean containers daily
   15:42 The stages (instars) of the caterpillar
   16:11 The walkabout and final molt into a chrysalis
   18:19 Emergence of the adult butterfly from the chrysalis
   18:51 Releasing the adult
   19:00 Not everything works out with the rearing process
   19:19 Don't handle monarch caterpillars
   19:51 How many caterpillars are responsible for rearing?
21:53 If captive rearing is discouraged, what can be done to help monarch butterflies?
23:49 efforts to support monarch butterfly habitat
24:32 Monarch Waystation Program
29:15 Upcoming Monarch Migration Festival. Thank you and see you next week!

Monarch Migration Festival, Sept 6, 2025 https://extension.illinois.edu/events/2025-09-06-11th-annual-monarch-migration-festival

Xerces Society Keep Monarchs Wild https://www.xerces.org/blog/keep-monarchs-wild

Monarch Butterfly Science w/ Dr. Andy Davis https://www.youtube.com/watch?v=zIt-zkivDjI

Monarch Butterfly Status Update w/ Brodie Dunn https://www.youtube.com/watch?v=dmqQlyPY1TA

University of Illinois Extension Pollinator Pockets https://extension.illinois.edu/cfiv/pollinator-pockets

University of Illinois Extension Pollinator Website https://illinoispollinators.org/

Contact us! 
Chris Enroth: cenroth@illinois.edu
Ken Johnson: kjohnso@illinois.edu 


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Creators and Guests

Host
Chris Enroth
University of Illinois Extension Horticulture Educator serving Henderson, Knox, McDonough, and Warren Counties
Host
Ken Johnson
University of Illinois Extension Horticulture Educator serving Calhoun, Cass, Greene, Morgan, and Scott Counties

What is Good Growing?

Talking all things horticulture, ecology, and design.

Chris:

Welcome to the Good Growing podcast. I am Chris Enroth, horticulture educator with the University of Illinois Extension coming at you from Macomb, Illinois. Monarch butterflies. Population decline? Should we help them by rearing them indoors?

Chris:

How do you rear them indoors responsibly? These are the things that will be discussed briefly today and we have a lot more information for you in the show notes if you wanna dig a little bit further. But I would say when it comes to monarch butterflies, really butterflies in general, they make us happy. We love seeing butterflies. And monarchs being so recognizable, they are present across most of North America, it is something that is a shared bond or relationship with all of us here on the continent.

Chris:

And it's something especially it is the time of year, as we are late in the season here, let's say we're being recorded August 27. I am doing a lot of traveling, whether it's for work or for kids sports, but I see a lot of monarch butterflies in the distance and every so often I see one right in front of the windshield. So this is the time I'm also cringing a lot as I hold onto the steering wheel knowing I just hit a butterfly. So I would say mother nature has designed for a lot in the world, but I don't think she could have foreseen the implications of the automobile. In addition to cars, monarch butterflies face all manner of adversity.

Chris:

So as they try to go from egg to caterpillar to butterfly, there are all kinds of things that want to eat them, infect them, parasitize them, and eat them from the inside out, and then all of the other things that can occur to them, just environmental or unforeseen or human caused actions. In the past I have seen monarch caterpillars picked up off of milkweed by yellowjackets, have watched them munched on by praying mantis, but one of the more notorious diseases that they face is one known as Ophreocitis electroscira, which, as a mouthful, we call that OE for short. OE is a protozoan parasite. It needs a monarch butterfly to spread and move around the environment, But in return, this one celled organism, a protozoan, will kill the monarch butterfly. So I don't think it seems quite like a fair trade.

Chris:

And monarch problems, they go beyond the things that nature throws at it in terms of predators, parasites, and disease, and my minivan. There's also clean farming practices, clean landscaping practices where we must have a tidy landscape where we often wind up limiting the amount of weeds, one of these being milkweed, which is the only thing a monarch caterpillar will eat, and then nectar sources for adult butterflies. And I would say that last one is definitely a critical thing that we'll probably get into here in just a bit. When we look at the monarch butterfly habitat that used to exist here, especially in Illinois, we know that about 90% of that habitat has been flipped into agricultural production. The urban environment is not very hospitable either, where we have gone from potentially prairie or woodland timber into large expanses of concrete, building structures, and lots of turf grass, which provides very little habitat unless you are a, I guess, a car or a golfer.

Chris:

And of course, there's the ever present implications of climate change which is having an impact on monarch butterflies. It seems as though everything is just at odds with the survival of the monarch butterfly. In fact, that survival rate in some cases is less than one percent in order to get that that insect from an egg all the way up to a breeding adult. So how could we change that? Or maybe a different question is how should we be trying to change that?

Chris:

So this is when the idea of raising or rearing monarchs indoors comes to light because we think, well, maybe we could take that one percent survival rate and flip that to a ninety nine percent survival rate if we would take them from the milkweed plant outside and bring them indoors. It's not a crazy notion. We do wild or captive rearing for a lot of other endangered species out there. Now monarchs are not endangered species, at least not right now. But when those captive rearing projects are ongoing, they are very selective in what animals they are choosing, how they are recording the data, and it is a very controlled environment in terms of making sure that this animal is not becoming too acclimated perhaps to humans.

Chris:

Now there are also other insects and butterflies out there that are also being captive reared for the preservation of their species. But those are very often instances where that insect or that animal is a localized species. It only occurs in this specific area. When we talk monarch butterflies, again, as we mentioned at the top of the show here, we are talking about an insect that covers the entirety of North America. Chances are you know someone or your kids or grandkids have already been doing something like this in school.

Chris:

I know in years past, my kids, they had experienced indoor monarch rearing in their kindergarten classrooms. I think it was a pretty good experience in terms of teaching them the insect life cycle, showing them how things change from egg to larva to adult, and then showing just, you know, the appreciation that we can have for the smaller animals of this world, and that everyone has its place or its part. And I think it also does a great job of showing that there are specific relationships that happen in nature. For instance, the monarch female, she will only lay her eggs on the milkweed. Monarch caterpillar has evolved and adapted to eating milkweed, which does exude a milky white substance that can be toxic to some, but it has evolved the ability to munch on that leaf without triggering that milky white substance.

Chris:

And so I think it just shows and it's a great teachable moment where they can take that and hopefully apply that to everything else that happens in nature around them. However, there is still a growing body of evidence in the scientific community showing that the indoor raising or captive rearing, as it's also called, of monarch butterflies is potentially detrimental to the wild population. So let's touch on some of those reasons why we would perhaps not want to be captive rearing our monarch butterflies. I'd say one of the main reasons that I see in the biology world in terms of captive rearing and why it might have negative consequences is that it's the idea of fitness. It is a very human thing to take a wild animal that we could potentially save and nurture and raise and then release it back out into the wild.

Chris:

However, there is this idea that caterpillars are soft bodied insects. And as we've mentioned before, there's a lot of things that eat caterpillars, there's lot of things that eat monarch caterpillars. Even though they might not be as tasty to some animals, they are tasty to a few animals out there. And so they are supposed to be food. That 1% survival rate has likely been designed or bred or evolved into that natural selection process.

Chris:

And so it is saying that the most fit caterpillar is the one is the one that that can, should be making it to adulthood. Are monarch caterpillars fighters? Well, kind of. They can kind of jerk or move their head when certain predators come near, how they position themselves on the milkweed to be more of a defensive or more of a camouflage position is important. And so there are these fitness things.

Chris:

And then of course there's the disease. And so if we are pulling these caterpillars out of the wild that are more susceptible to disease and then they pass those genetics on to future generations, we are now building in a more higher susceptibility to potential diseases like OE in the caterpillar populations. Another concern that does come up is that because some caterpillars are not supposed to make it in the wild, If we do artificially inflate that population, do we have the resources to support that higher population level? And so this means that if we're keeping higher densities in the wild, do we have the milkweed to sustain them? Do we have the nectar sources to keep them going?

Chris:

And if there are more of them, if they are at higher densities, is the chances of disease going to increase for them? If you are saying, well, you know what, I don't know if I buy into this, there seems like more reasons why we should be captive free monarchs than that, well, we actually have an episode where we really dive into this topic with Doctor. Andy Davis with the University of Georgia who studies this topic. We will leave a link to that one in the show notes down below if you want to learn more about this. And also, this is something that is being advocated more by other organizations, say, like Xerxes Society, that we will also leave links to their articles down below as well.

Chris:

This next part, I'm debating whether or not I'm going to leave it into the episode, but I figured you might be watching this still like, well, I to rear a couple monarchs, maybe I want to tag them for scientific purposes, maybe I want to be able to show this to classroom of kids. And so I get it. You are looking for that information. There are procedures that you can do this more responsibly. Again, definitely not advocating for the raising of hundreds, hundreds or thousands of monarch caterpillars, we cannot save them by raising them indoors.

Chris:

We'll talk about other options here in a bit. So but if you are interested in captive reared monarch butterflies with caterpillars really, here are some tips, maybe a procedure that you can go by that can help you be more successful and hopefully limit the spread of disease which is one of the big concerns that we do have with captive rearing. So let's get started. Monarch caterpillars only eat milkweed. Now I think a lot of folks are familiar with common milkweed.

Chris:

It is found all across Illinois and across the Midwest. There is definitely that. But there are more than two dozen species of milkweed native to Illinois. So there's many different types. I would say late in the season I find a lot of monarch caterpillars on my swamp milkweed.

Chris:

Swamp milkweed has very narrow leaves, it might be more difficult to keep that in stock because swamp milkweed, at least this time of the year, is really starting to decline, whereas common milkweed, it still has a few more weeks left in it. And so I would say if you're scouting, scout around for common milkweed. It's Asclepis cerecia and or cirica, as Ken and I have debated on this show. And so just I would say scout around for that, those are usually a bit more long lasting, or butterfly weed is the orange flowering one, that's another one that might last a little bit longer. And the other thing is that what I typically see is that whatever species that monarch female has later egg on and that caterpillar has hatched and has started eating, it really just tends to stick to that species.

Chris:

I have pulled out honey vine milkweed that has had monarch caterpillars on it and I've actually closed pinned it to my swamp milkweed. They didn't go to it. They just seem to refuse to jump from the honey vine weed over the swamp milkweed. I'm not sure why, I'm sure someone out there has a better explanation than mine which is I don't know, they just don't like it. So alright, so you have your milkweed, you're scouting for them, you find a caterpillar, bring that inside.

Chris:

The thing about feeding them, think is the other important thing is as you're pulling leaves off the milkweed plants, want them to be think of it as lettuce. You know, what would you eat? And so the smaller, tender leaves, they're probably those more choice that a caterpillar would prefer to eat, and also layer eggs, and so those are ones to scout and to bring inside. Wash it before you bring it to feed your caterpillars, but before washing it, make sure that you don't spot any other eggs or any other insects on there that you might be washing off. Remember milkweed plants are a whole world of diverse amount of insect species and other things that are living on it.

Chris:

In terms of containers, I think you can transition containers when you first bring them in. You can have a smaller container. Plastic works well in this case because it is something that you can sanitize to limit that disease spread. You'll want to keep a wet paper towel on the bottom where you keep your that will help keep your milkweed leaf hydrated. And the smaller container helps you keep track of caterpillars, it just makes it easier to see them and find them.

Chris:

And you can transition up to larger containers as they get bigger and you might need more and more milkweed plants to keep them going. Another important thing is about where you place your rearing cage is that temperature affects everything in this process, and so the warmer the temperature, the faster the egg or caterpillar or pupa will develop into an adult butterfly. You're going to want to check and clean those containers daily. You know, first, you know, we're kind of also thinking about the caterpillar poop or the fancy word for this is frass that they will generate. And as they're small caterpillars, the frass is going to be like pepper flakes or something.

Chris:

But as they get bigger they are going to be much larger chunks of frass and so you're going to want to clean those out every single day. Every caterpillar is going to molt. This means the process that happens is that they usually become very still for a period of time. Kids in the classroom also say, oh, something's wrong with the caterpillar, it's not eating, it's not moving. What might be happening right then is that it might be molting.

Chris:

And what it does, it puts down a little silk pad, anchors it, and then it will split out of its skin and it'll crawl out and it will leave its skin behind. And sometimes it might even eat its own skin. So the last time the caterpillar molts is when it will form its J and form that chrysalis. And as it gets ready for that last molt, it's going to do a walkabout. Essentially what this is, is it's the caterpillar's strategy to get it off of that milkweed plant and get it somewhere maybe more sheltered, maybe a bit more safe where it can go into its pupil case or its chrysalis and then spend a week or two in that case and then develop into that adult butterfly.

Chris:

So it will want to leave the milkweed plant, it'll want to leave and that's why we often will find those chrysalis hanging in odd or awkward spots in the cage and sometimes if it escapes, in odd and awkward spots around the house or classroom. This is when transitioning maybe to a taller container might be best. So once it finds its ideal spot, it will put down its silk button and it will put its feet into that button and then it will hang from that position in a J, like a capital J shape. And it might hang like that for eighteen hours or longer. You will then, after it hangs there and it determines that it is ready to make that final molt, it's going to straighten out and it's going to do what's kind of termed the pupa dance.

Chris:

It's going to wiggle around and that means that wiggling is the splitting open of its skin for one last time, it'll wiggle out of it and it will form that chrysalis around it. And you know this kind of amazing part of metamorphosis here is that it sort of just liquefies and it looks nothing like a caterpillar, looks nothing like a butterfly. It is the in between that it is in right then and there. The chrysalis will hang in this position in its chrysalis for anywhere from eight to twelve days. Once you see it start to turn dark, black, you start seeing maybe the colors of those wings behind that chrysalis case, this is a signal that you are about to have an adult monarch butterfly.

Chris:

Once the adult butterfly emerges or ecloses, it will hang there for a period of time, it's going to dry its wings and it's going to pump the fluid that's in its body into its wings. It's going to look kind of deflated at And it's going to spend several hours doing this. And generally, after eclosing, the adult butterfly will not eat for about twenty four hours. It'll just hang out there, getting ready for its journey and if this is the migration generation, it is getting ready for a very long journey indeed. So only release your adult back out into the wild making sure that it is a rain free day and ideally when temperatures are above 55 degrees Fahrenheit.

Chris:

And keep in mind as you are raising monarch caterpillars, things are going to happen that will lead to its death. There might be parasites in it, there might be disease, I have seen on instance where milkweed has been sprayed with an insecticide on accident, and all other kinds of unexplained things. Another big thing is avoid handling the caterpillar. You don't want to pick it up and move it around when you move it, you want to make sure that you're picking it up on whatever leaf or stem that it is on and moving it that way. If it has, say, getting ready to molt and put its silk pad down, you might injure it or potentially kill it by picking up that caterpillar and moving around.

Chris:

So make sure that you're never moving or handling that caterpillar wherever it is resting. Now, how many caterpillars could you, should you, would you want to rear indoors that would still be responsible? Well, Xerxes Society says no more than 10. But if you're doing that, 10 extra butterflies in the monarch population is not going to make much of a difference. However, there are many more people doing this across North America in classrooms, at home.

Chris:

There's even companies that are doing this. And so when we factor this out, you know, one person who is raising 10, not as much, but if you get a million people raising 10, well that starts to become a major contributor to the population genetics occurring in the monarch, but wild monarch butterflies. And so I would suggest or recommend that if this is something that interests you, limit your number to 10. If you could hold off doing this, maybe participate, maybe use your rearing as part of a classroom. You can bring it into a classroom.

Chris:

That way the classroom, they don't have to rear their own monarch butterflies. Essentially, we're trying to reduce this number so that we're not being oh, contributing what might be a lack of fitness into the wild monarch population. Well, alright, I have maybe come down pretty hard on those who like to rear monarch butterflies, and I will say I've done this myself. We have had successes at home, we have had failures, I have watched flies emerge from monarch butterflies as parasites. Has been a it has been a great learning experience, I'll say that.

Chris:

And my kids might always be scarred for life watching those little fly larvae crawl their way out of the monarch butterfly caterpillar. But so if I've come down hard and you're saying well what can we do? I'd say of all the the research papers and all the things that I've read about monarch butterflies and the things, the problems they have, the things that are, you know, affecting their population, whether it's disease, predators, parasites, pesticides, climate change, You know, these research papers, you know, they try to quantify and indicate these particular things, but it's almost every single research paper. If you just go all the way to the end, that conclusion section, they all say, yes, whatever it is we were studying, it might, is, could be, or isn't potential factor in monarch decline, but they all say the number one contributor to monarch butterfly decline is habitat. There's just not enough of it.

Chris:

And when we look at the populations that occur in Illinois, we actually see a rebound effect in the summer months here. So it seems as though the population levels are able to push back to where they were the year before. So what is it that might potentially be affecting that overall population? Well, we look specifically at that migration generation, moving from some all the way up into Canada all the way down to Mexico. And the lack of nectar sources, floral resources for these butterflies to have fuel and energy to get them to where they need to be to overwinter down in Mexico.

Chris:

That is a major contributor to the decline of the monarch butterfly population. And it's the one of the major concerns, it's habitat. Habitat loss. So what can we do to support monarch habitat? Well, I mean, volunteer local conservation groups.

Chris:

Illinois Extension has a Master Naturalist program that is just conservation volunteers, we go out and educate folks about wildlife, plants, animals, all that stuff that happens in nature around us. Support local land preservation, you know, community pollinator projects. These are all ways to do this. And I do have one idea, one thing that we have been doing actually here in Western Illinois locally, which has seemed to prove some results. And I want to talk about a program that you could potentially enroll in, that is the Monarch Waystation program.

Chris:

Monarch Waystation program started at University of Kansas. Chip Taylor began this program where you could certify a piece of property as a Monarch Waystation. So a waystation would be like a garden, it could be as small as a couple containers, there's no really minimum size here. It could be a garden size, pollinator backyard size, it could be a prairie. But what it is is just getting dots on the map.

Chris:

Where are we creating habitat in North America? And what this habitat provides is that larval food source for the caterpillar and a nectar source for the adult butterfly, especially food sources for that migration generation. I believe you can go online, we'll leave links to the weigh station program down below. Now there's all different types of programs as well. That's what originated in Kansas, it is now kind of more of a nationwide program.

Chris:

University of Illinois Extension, we have our own, we have our pollinator pockets program, we have our conservation home program, we have a lot of habitat programs that you can even do here with our organization. But I like this waste station program because a long time ago, I would say maybe twelve years ago, some of our Master Gardener volunteers and I, we got together and we said, well how can we measure that we're making an impact with our monarch butterfly education? And so I said, well if we can tell people about monarch butterfly, how we can provide habitat for our wildlife and get them to sign up as a Monarch Waystation, then that is data that shows that we're having effect. You can actually go on the waystation website and there's a database of where these weigh stations are located in the country. And so when we draw like a radius circle around our neck of the woods, and after a few years of doing this effort, we can see a significant increase in Monarch Way stations in our part of the state of Illinois, which I go to say that that means that we are having an impact.

Chris:

Now, there's nothing better than a little bit of competition, I would say, when it comes to anything human related, right? And so our goal with, you know, you know, kind of our volunteer goal, our Master Gardeners and now Master Naturalists program, which has sprung up since then, our goal is to make our part of Illinois and then Illinois the state the Monarch Waystation capital. And so here's where the numbers stand right now. There are currently 52,932 Monarch Waystation habitats as of 08/15/2025. That is nationwide, that is across the country, and there's even a few in Australia as well.

Chris:

Now, when we break this out by state, we Illinois is in second place. The first place is Texas with 4,271 way stations. But Illinois, we have only we are currently at 4,078 way stations. We have like 200 way stations to go and we can overtake Texas and be in the lead. So come on, Illinois.

Chris:

If you are in Illinois or anywhere in the country, but Illinois, I mean, come on, I got this little competitive spirit here. If we can get 200 more weigh stations registered out there, if you have milkweed, if you have nectar sources, if you are stewarding the landscape for monarchs, for other wild native insects, for birds, reptiles, mammals, any of that. It all contributes to that. Register for that Monarch Waystation. It does cost $18 processing fee, and if you want to pay double that $36 they will send you an aluminum sign as well.

Chris:

You will get a specific number, you'll appear on their registry, and you can put up that aluminum sign, which generates conversation with other people in the community. People see that, they say, oh, well that's what we can, something we could do to help in conservation. And it just gets people talking, it gets the conversation started about habitat conservation and how we can incorporate that into our agricultural and our landscape lands that we live, work, and play in. Well, was a lot of great information about monarch butterflies, everything from their adversities that they encounter to tips for rearing them, which again, I don't really recommend we do that. Maybe save those for special occasions, special events.

Chris:

And if you are going to do that, make sure that you do only 10 or less than that. And so, yeah, restrain yourself. And actually, coming up, we have an event that we do every year in Galesburg. It is called the Monarch Migration Festival. It happens it always happens the Saturday after Labor Day.

Chris:

This year, is September 6. It will be in the morning. It's going to be at Galesburg Nature Center in Galesburg, Illinois. And this is essentially where we just get together. We have education stations.

Chris:

There's a few vendors. We got music. We got stories, and yes, we will even release some tagged captive reared monarch butterflies. And so we're just getting together to sort of celebrate, it's the end of the season, It's the end of the growing season. The monarch butterflies are migrating south, and it's it is a celebration of that.

Chris:

And so, hey, come check us out. If you can't make it this year, again, we're there every year. The first Saturday or this is Saturday after Labor Day in Galesburg, Illinois. It is a fun time and people come from all over to attend. Well, the Good Growing podcast is a production of University of Illinois Extension, edited this week by me, Chris Enroth.

Chris:

Hey, listeners. Thank you for doing what you do best and that is listening. Or if you watched us on YouTube, watching. And as always, keep on growing. Hey, A big thanks for you.

Chris:

Thank you for doing what you do do do. You do do best. What you do do best.