Are monarch butterflies poisonous?

by / Jun 01, 2022



This post is edited from an episode of the Is That True? Podcast, where host Arionne fact-checks different kid questions. Today’s episode is a question about monarch butterflies from Yousef.  

Arionne: Our very first fact we’ll be investigating is a really cool one. 


Yousef: My name is Yousef and I’m 8 years old. And I live in Illinois. 


And did you know a monarch butterfly is poisonous?


Arionne: Wow, Yousef. That’s such a cool fact. And I have no idea if that’s true! So, we’ll have to investigate it.


But first, let’s talk a little bit about butterflies and how I found someone to help us figure things out.


I know from school that butterflies are extremely cool. In fact, they used to be my favorite thing to study when I was a kid. They start off as caterpillars and go through what is called metamorphosis. That means the process from starting as one thing and turning into something completely different.


When I was a kid, we kept caterpillars in our classroom and watched them turn into butterflies so I know just how cool it is — I actually saw it happen with my own eyes! That’s one way to know how something is true. But what I don’t know is whether or not monarch butterflies are poisonous. I’ve never tried to research that! But I was scrolling online and saw someone who does. And judging by his very cool educational videos, he’s the perfect person for us to meet!

Dr. Sammy : So my name is Dr. Sammy, Samuel Ramsey, or Dr. Buggs. There's a lot of people who have been calling me. Uh, I am an entomologist with the United States Department of Agriculture and I'm a science communicator. 


I love getting people excited about the incredible stuff that goes on in the natural world.


Arionne: It’s a pretty cool thing to have a nickname based off what you love and what you love to study, huh? But Dr. Sammy wasn’t always so ready to fearlessly learn about bugs. When he was younger, he was actually scared of them — just like some of us might be. 


Dr. Sammy: I was actually terrified of insects when I was a kid, um, so much so that my parents were really worried about it because I didn't want to go outside for recess. I was having nightmares about bugs. And so they told me, “People fear what they don't understand.” So they got me a library card as a seven year old, which I think was just the perfect idea.


And they indulge my curiosity there. They got me all these books about insects from the library. And by the end of that summer, I was like, “Mom, Dad, I want to be an entomologist when I grow up!” And here we are. 





Arionne: So Dr. Sammy has been into, well, bugs ever since. So if there’s anyone who would know about our fact, it would be him. So I asked:


So, is it true that Monarch butterflies are poisonous? Because they're so pretty. 


Dr. Sammy: It's so interesting that these butterflies actually are poisonous. They're poisonous because they feed only on a plant that is poisonous. They're one of very, very, very few creatures on this planet that can eat something called milkweed. 


We call it milkweed because if you tear it, the little pods, this milky substance comes out of it, and it is poisonous. It's full of a toxic chemical called the glycoside. Um, and if sheep or cows eat enough of it. It can kill them, the caterpillars feed on this, and it doesn't hurt them, but they're able to store all of those glycosides inside of their bodies so that if something tries to eat them, it can be poisoned by it.


Arionne: So yes, Yousef and friends! Monarch butterflies ARE poisonous. And Dr. Sammy taught me another important point — that there is a HUGE difference between something being poisonous and something being venomous. That’s honestly something I think we mix up. Or at least, I do!


Dr. Sammy: A lot of times when people hear the word poisonous, they think of a venomous creature. They think of something like a scorpion or a tarantula. Those are creatures that have venom. That means that the toxin that they use against another creature, they have to inject it into that creature's bloodstream. 


So they have to bite them or sting them or something like that. So a wasp. Is a venomous creature, but it's not poisonous. You could actually eat one, but I wouldn't recommend it though. Don't try that. But a butterfly, certain kinds of butterflies, like specifically the monarch butterfly— what we think of as being very pretty—isn't an attempt for them to show off how lovely they are to us. It's actually an attempt for them to communicate, I'm poisonous. And I don't want you to have to bite me to find that out. So when you see a creature that uses that black and orange coloration or black and red, like a ladybug, which is also poisonous or a firefly, which is also poisonous, you don't want to eat that creature. 


Arionne: So because monarch butterflies are poisonous and not venomous, they are NOT dangerous for people. Mostly because we don’t go around trying to eat a bunch of them.


Dr. Sammy: We're big enough where it wouldn't hurt us very much. You get an upset stomach. But for the most part, it's not a concern to humans, but birds or mice that attempt to eat one will not eat another one. 


They'll start throwing up and it'll be a really rough day for them. 


Arionne: I think it’s easy to forget just how cool butterflies are. It’s also really good for us to remember that butterflies, well, they start off as something totally different. They start off as caterpillars. 




Dr. Sammy: So insects like butterflies and caterpillars go through a process called metamorphosis. The big grand term that we have for all the insects that go through this full metamorphosis is the Holometabola. And they're really, really, really fascinating because they transitioned from one creature into something that looks totally different. And if you didn't know, you wouldn't even think they were the same species. The concept of Pokemon is actually based on the process of metamorphosis in insects. If you've seen Pokemon that can change from one Pokemon to the next Pokemon, I think it's so cool that the guy who came up with all of this was obsessed with bugs and was really enamored with the concept of metamorphosis as a method of even inspiring something as cool as Pokemon. But one of the things that I have found really cool about metamorphosis is that you're taking a creature. This organism is somehow able to restructure its own body into another thing. 


So if you're building something yourself, imagine you've got a bunch of Legos and you want to build a big Lego castle, you're building something that is not a part of you, but for a creature to break itself down and then turn itself into something else is crazy to me. And the fact that its body can keep score. It can remember the things that happened when it was a caterpillar, even though it's got a different brain as a butterfly is also a marvel to us as scientists.


Arionne: And when we think about how a caterpillar can change into a butterfly, Dr. Sammy reminds us that THAT is kind of what we do, too!


Dr. Sammy: When you're growing up, there are some changes that happen rapidly and you can look back at when you were a kid. When I like to call high school, the pupil phase, you are in your little cocoon, figuring things out, and then you turn into an adult and it just seems like the transition is so rapid and like you're a different creature in a lot of ways.


Arionne: We actually have a lot in common with bugs! All we have to do is just look around. Or more specifically, look down. 


Dr. Sammy: I think people need to look down more. Look down and remember that bugs are the coolest thing that you've ever stepped on. Instead of just smashing them, take a moment to think about just how intricate and interesting their world is. You will not be disappointed.