Science Friday - Beautiful botflies, luscious leeches, and the wonder of parasites

Episode Date: July 14, 2026

Dino Martins has plucked maggots out of a dead elephant, pulled botflies out of camel snot, and willingly let a horsefly feast on him. Why? Because he’s obsessed with parasites. Dino is an entomologist who grew up in rural Kenya, and he’s worked all over the world studying how insects keep this planet alive. And along the way, he met some of the world’s most iconic freeloaders, which he describes in his new book, “Hidden Creatures: Luscious Leeches, Bashful Botflies, and the Wondrous, History-Shaping World of Parasites.” Flora speaks with Dino about his unlikely journey into science, the beauty and disgust of parasites, and why these little moochers deserve more of our care. Guest: Dr. Dino Martins is an entomologist and evolutionary biologist based in Malindi, Kenya. He’s the author of Hidden Creatures: Luscious Leeches, Bashful Botflies, and the Wondrous, History-Shaping World of Parasites. Other episodes you may enjoy: Tiny wasps emerge from a caterpillar, and reveal a hidden world Should We Conserve Parasites? Some Scientists Say Yes Transcripts for each episode are available within 1-3 days at sciencefriday.com. Subscribe to this podcast. Follow our show on Instagram, TikTok, Facebook, and Bluesky @scifri and sign up for our newsletters. Got a science question that’s keeping you up at night? Call us: 877-472-4374 Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Hey, it's Flora and you're listening to Science Friday. Dr. Dino Martens has plucked maggots out of a dead elephant, pulled bot flies out of camel snot, and let a horsefly feast on him consentingly. Why? Because he's obsessed with parasites. Dino is an entomologist who grew up in rural Kenya. He's worked all over the world to try to understand how insects keep this planet alive. and along the way, he met some of the world's most iconic freeloaders. Dino describes his journey into science and his love of parasites in his new book,

Hidden Creatures, Luscious Leeches, Bashful Botflies, and the wondrous history-shaping world of parasites. Dino, welcome to Science Friday. Thank you so much, Flora. Delighted to be here. I am delighted to have you. And I have to spend right off the bat a minute on those adjectives, luscious leeches, bashful bot,

I feel like you are doing the most to try to rebrand parasites. Why? Absolutely. So first of all, parasites are disgusting. I accept that. And they can be deadly as well. But they are also part of the fabric of life.

And I think for me, as a naturalist, as a scientist, if we're going to learn about things that are beautiful and interesting, we also have to learn about things that are disgusting and maybe even slightly sort of disturbing. I'm sold. I mean, what makes a parasite a parasite? Do you have, is it just you're a moocher? You know, that's a really fantastic question because there isn't a single definition of parasites. And if we think about a parasite being something that, you know, feeds on other things, but in what units, is one of the things that biologists kind of debate. And I remember E.O. Wilson saying that, you know, he really liked precise definitions.

And his definition was centered on the idea of a parasite being anything that fed on its prey in units of less than one. What does that mean a unit of less than one? So if you were a cow grazing on grass, you wouldn't be a parasite, even though. you're feeding on something else. But if you're a tick feeding on the cow, you are a parasite because you're feeding in units of less than one. So it's, it's, you know, like so many of these definitions in science, the closer you look, the more complicated it becomes.

And it's very easy for us to define a parasitic relationship where, you know, a parasite is taking, deriving benefits, nutrients, whatever. else it's grabbing, it's mooching off others. And the host, who is being targeted, is paying a cost. So parasitic relationships are very easy to kind of quantify in a mathematical sense or in this kind of scientific sense. But when you actually look at nature, there's a lot of gray areas. Are hosts always paying a cost? I mean, I'm thinking of like our evolving understanding of the microbiome. and how we have, you know, bugs deriving nutrients from us, but also doing a service. Do you think that there's a world in which we just don't understand parasites well enough yet to understand the relationship?

Absolutely. Just like the microbiome, our perception of parasites is starting to shift. Now, there's no question there are many parasites that cause a tremendous amount of suffering and have a huge impact. But the question is, we have, as you said, evolved and co-evolved with parasites, as have many other creatures in the world. And so could there be a benefit in one way or another to actually encountering parasites? And the evidence is starting to gather, and the answer is yes. So just like the microbiome with all its complexity, exposure to parasites, perhaps when you're younger, for example, to certain parasites, helps build and train your immune system to deal with more dangerous or deadly things it might encounter later on in life. Parasites have all kinds of

molecules and chemistry and weird genetics and extremely disturbing sex lives and all of these aspects. Do you want to give us an example as long as we're here? As long as we're here, yes. So I describe how mosquitoes actually mate in the book. I'm with my students and we see them mating. And they mate in the missionary position, which is extremely entertaining for the students. And not sort of what we would expect of mosquitoes. You know, you'd think they'd be a little bit more kind of, you know, sort of, who knows?

I'm struggling to find the right word here. It's hard to know what it would be like. Yes. I have to say it's not something I've thought about before. But, you know, ticks are another amazing one and some species mate on the host, like on the dog. And the male actually has to do like all this foreplay to get the female really sort of in the mood and excited. And then this, you know, this might be too much for listeners or for sensitive nature, but he actually uses his mouth parts to do it. And yes, I'll just leave it at that.

You got a warning, listeners. Let's talk about your path to parasites. I want to go back to when you were a kid, and I don't think I've ever uttered the sentence. But growing up, you had a pet baby zebra. How did he come into your life? Yes, I did. You know, so I was very lucky to live in different parts of Kenya growing up. lived for part of the time on the plain south of Nairobi at a place called Kittengela and surrounded by all kinds of different animals.

And, well, BZ, as we called him, which stands for baby zebra, he, yes, we weren't very imaginative with some of the names. We also had craney and who was a crane and Mary Boo, who was a Maribu stalk. So BZ kind of fitted with the rest of them. family. What happened there was a drought? And during drought, you know, many baby animals, other animals get kind of abandoned or there's other kind of disruptions. And that's how BZ was found because he'd been in the drought. He'd been abandoned. He was very thin and kind of full of parasites and starving. So he was found one day and he was brought to me and I had to learn how to take care of him. So BZ had this eye parasite. And I want to talk about your

response to that. So you saw the sort of worms coming out of his eyes. And I think many people would be like, oh, that's gross. You were like, I have to know more. And not only pulled them out and looked at them under the microscope you had access to, you went, it sounds like, to a vet's office to look at it under an even stronger microscope. And I wondered, is this sort of who you've always been just sort of determined to follow your curiosity? Absolutely. And I've been very lucky to have teachers and vets and lots of other people who've supported me and encouraged me in being curious. But even when I haven't had a lot of encouragement, I'm very curious and I can be quite in a very, I think a gentle way be quite pushy.

And I remember in school showing up with various parasites. And some of the teachers were horrified, but at least they didn't discourage me. They were like, okay, we can learn about this. Does your scientific interest in insects and now also the side quest into parasites relate to where you grew up and where you've decided to live and work? Absolutely. And I think one of the things about insects, you know, everyone was like, you grew up in Kenya. Why didn't you study lions or rhinos or elephants or go off and study even, you know, other big animals? But growing up, I was often quite alone and I had to kind of entertain myself. And the thing is, insects are easy to find. I could find them and I could catch them and I could observe them really closely, which is something I've always wanted to do. is to really see things and see all the details. And so insects became my companions, they became my friends.

I would turn them into characters in my imagination. I would draw them. And as a result, I started learning that by seeing these details, you start to understand what's happening beneath the surface, beneath what is really obvious, you know, and that was like, wow. you know, just so mind-blowing. And in the book, I talk about, you know, raising caterpillars and watching one, you know,

sort of parasites erupt from its body, which is absolutely horrifying to watch, especially when you've cared for this caterpillar and you've been feeding it every day. And, you know, you feel like it's your, it's, you really care about it. But then it's being like eaten alive, which is horrifying. And then you actually watch what happens next, which is these wasps. emerging. And then you realize in some insects, actually there are parasites of parasites. And it's just like, at first you're almost like, I might get a headache from thinking about all of this because it's so complicated, but then it's actually so wonderful as well.

I have to take a quick break, but when we come back, do we need all parasites? Really? Stay with us. We've been reading about parasites a lot right now. Screw worms. cyclosporiasis, giving people stomach distress in the U.S. right now. Of course, malaria, ticks, carrying diseases. Are there some that you think we could wipe out? Okay. So that's an interesting question. It's a moral question as well as a biological one. And the answer is, you know, in some ways, yes. We already have eradicated certain pathogens that are, you know, have caused diseases through history. smallpox, for example, Rindapest, which was a viral disease that used to kill animals here. And, you know, it was transformative for the ecology and the empire and the political outcomes for

many countries in terms of these changes. But I would make the case that the answer is no. We do not have the right to eradicate any other species, even though, of course, we do it all the time. But the challenge with parasites is this, is that we need to approach it with a little humility. Parasites are not as simple as viruses. They are actually complex organisms that can think and can behave and can adapt and can respond. They can exploit opportunities that we create for them, whether it's through the increased concentration of animals in feedlots, or it's through fish farming or it's through transporting animals across the planet. We're changing the rules of the game all the time, but parasites are the one group of animals who are one step ahead of us.

They're like, okay, you change the rules. We're going to cheat and we're going to do this and we're going to exploit this opportunity. And I think we might think we can eradicate them or we can get rid of them, but I don't think we ever will because they are benefiting from what we're doing. And so I think the better way to approach is to say, look, here they are. They are part of this incredible fabric of life, this living system that supports us and all the people and animals we care about. How do we understand it better? How do we engage with it? How do we engage with it. And we do need to solve some very serious problems of parasite, you know, diseases, for example. And the only way we will do that is actually by, you know, better science, science that's much more collaborative, that's much more global. Because for parasites, there are only bodies. There are no borders. And the fact is, no matter where you are, who you are, how privileged you think you might be, how safe you might be, you think wherever you're living in a city or somewhere removed from nature, you know what?

You will never escape from a parasite. They are coming to get you. And so you better learn about them. You know, listening to you talk, it feels like you have a, you do a good job of holding both the sort of frightening elements of parasites, the wonder of them, the disgusting elements all at once. How do you do that? What's your secret? Thank you. I don't know if I do, but basically my secret is, I think, twofold. One is just to be curious, just be open-minded and to go out there and kind of be open to the unexpected. The other part of it is actually, you know, I'm very lucky to have animals as teachers as well.

And so understanding that on everybody, on every branch, on every single person, there is another orchard. And we might not sometimes want to think about it. It's like quite horrifying and disgusting. But if we don't, if we don't, we might miss out on some really cool stuff that's happening. It's just like you never know what you're going to find out there. And the remarkable thing is imagine the most horrific, bizarre, sci-fi scene you've ever, ever seen in a movie. and I can assure you that in nature, you will find something even more horrifying and wonderful all at once.

Okay, well, leave us with one great example, the cinematic parasite that you want us to all know and, if not love, revere. Oh, wow, gosh, that's a really great question. There's so many sort of racing through my mind. Let me try it. Let me try and think through this. One, if I were to think about one of the parasites that I often find with students that

completely horrifies them is the bot fly. And bot flies are, you know, these complex parasites, they're flies. The actual flying around as adult flies, you know, doing all kinds of fly-like behaviors and have to find each other and mate and then they have to lay their eggs. And the eggs develop, in some cases, in the nostrils or in the throat or in the stomach. Whose nostrils? Well, mostly it happens to other animals, but it has occasionally happened to people. But the botfly is like actively making these decisions.

You know, it has to navigate all this complexity. it has to get its eggs into the nostrils or the lips or the mouth of another animal. In the case of the rhinoceros or the horse botfly or the elephant one, in fact, they have to be swallowed. And isn't that wonderful and amazing to think about that this entire thing could be living inside you and thinking and making like all these decisions? And then, of course, it has to face this ultimate challenge. It has to get out of you back into the world. And, you know, that's like a really fraught moment. Why is it a fraught moment?

Because if you think about it, so for example, when they go into the nostrils of camels or deer, or maybe even people occasionally, that doesn't happen very often. Let me not terrify too many listeners. They have to get out. So what they do is they like tickle the inside of the nose. And so the animal sneezes. And now they've got to, they shoot out like a rocket, you know, flying across. And they've got to land in the right place. Because if they land on like, you know, the wrong place, they could, that could be it.

That could be the end of their life. And they've invested so much in getting to this point. So, so, you know, there's all like these risks they've got to overcome and all these probabilities that are sort of stacked against them. And yet somehow they make it, you know, some. how they make it and they're out there in the world just being fabulous, which is, which is wonderful. Do you know, I want to see the world through your eyes.

I feel like it's a, they would help with my brain chemistry. I believe that we all have the ability to see the details of nature, but I really don't think it's, it's me. I'm not very special. I'm just, you know, holding on to that childlike wonder that everybody has. but I also know that we as humans have this incredible ability to see detail and to engage with it. And we have all these senses that we can experience the world with. And so for me to really, for us to really understand and see the whole picture of life and nature and evolution,

we have to sort of see everything, hear everything, taste everything, feel everything, squirm alongside everything. And yes, the disgusting parts of it, and then in that disgusting moment, we'll realize, actually, you know, this is a bit divine as well. I love this call to action, Dino. Thank you. I really do.

Thank you. Dr. Dino Martens is an entomologist, an author of Hidden Creatures. He's based in Melendi, Kenya. Dino, thanks again for joining me today. Thank you so much. Take care. To sink your teeth into more Parasite stories, head to ScienceFriday.com slash parasites to read an excerpt from Dino's book.

This episode was produced by Russia Aredi. Thank you for listening, and we'll catch you next time. I'm Flora Lichtman.