Your bug roommates

Our houses are homes to hidden worlds of bugs. And the more ecologists explore those worlds, the more they realize that some of our creepy, crawly housemates actually have a lot to teach us. (First published in 2023) Guests: Rob Dunn, ecologist at NC State University and author of Never Home Alone; Michelle Trautwein, entomologist at the California Academy of Sciences For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠ And please email us! ⁠⁠[email protected]⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠ Help us plan for the future of Unexplainable by filling out a brief survey: ⁠⁠⁠⁠⁠⁠voxmedia.com/survey⁠⁠⁠⁠⁠⁠. Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

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• 1:11Speaker 02

  Rob Dunn used to travel far, far away from his home in the US to study some of the wildest places on earth: rainforests.

• 1:20Speaker 03

  I studied rare tropical insects. And so I'd go to Bolivia, or Australia, or Ghana, or Singapore, to try to understand the general rules that apply to those insects.

• 1:31Speaker 02

  He's an ecologist, so he'd look at how ants distribute seeds, or how insect populations can recover after a rainforest is clear-cut. And then he'd come back to the States.

• 1:43Speaker 03

  And I would give talks about those faraway places, about ants, or termites, or whatever. And always at the end of those talks, somebody would say something to the effect of, "Well, you know, that's great, but what do I do about the ants in my kitchen?"

• 1:56Speaker 02

  Rob's initial reaction was to dismiss those questions.

• 1:59Speaker 03

  And what I heard at first, you know, is a, like, I'm just presented about my life, work, and the things I care most about professionally, and you've asked how to kill them.

• 2:09Speaker 02

  But slowly, over time, Rob started to listen more closely. And he realized...

• 2:14Speaker 03

  What that question was really saying was, "I listened to your boring hour-long talk, and the only way it possibly relates to my life..."

• 2:24Speaker 03

  Isn't this where people were asking about the biology of their daily lives?

• 2:29Speaker 02

  Rob started to wonder, what would happen if he did study the biology of people's daily lives?

• 2:38Speaker 02

  He knew that there were some people who were actually studying bugs at home.

• 2:43Speaker 04

  I'm going to show you a couple of different things that we use to monitor bed bug issues.

• 2:46Speaker 02

  There are decades worth of ads out there reminding us that pest control researchers have done very thorough investigations into pest species. So those are species that spread disease.

• 2:58Speaker 05

  Look at those mosquitoes go for that unprotected arm.

• 3:01Speaker 02

  Species that destroy our stuff. Termites are monsters. Or just species that annoy us in some way.

• 3:08Speaker 03

  So it's not like we don't know anything. We know what kills them.

• 3:11Speaker 05

  Head and roach killer kills bugs dead.

• 3:14Speaker 03

  We know if you spray them, like in what precise way do they roll over and twitch? Like, we know that in great detail.

• 3:20Speaker 02

  But as he was looking around, Rob realized that researchers did not yet know many of the answers to the kinds of questions that ecologists like him like to ask. So less, how do I kill these cockroaches? And more, how did these cockroaches evolve to suit this environment? Or like, which species are in this home besides cockroaches? Who's eating who and how and why? And what does this ecosystem need to thrive?

• 3:49Speaker 02

  So Rob decided to start asking those questions.

• 3:52Speaker 03

  I would realize that all the things I was studying in rainforests, I could also study in houses.

• 3:57Speaker 02

  And when he started exploring houses like they were rainforests, Rob discovered just how little we actually know about our arthropod remains. Like, how little we even know about how many species live with us, let alone what they're up to. But he also realized how much we might benefit from these bugs if we stopped zapping all of them dead. Because, yes, some household bugs really are pests, but others don't harm us and could even be helpful to us.

• 4:30Speaker 02

  I'm Byrd Pinkerton. This is Unexplainable. And this week, we're exploring our rooms as if they were rainforests and learning how unlocking the secrets of the bugs that live in them could potentially change our lives.

• 4:59Speaker 02

  Rob's career pivot to exploring homes actually involved a lot of different projects covering a lot of different organisms around the house.

• 5:06Speaker 03

  And so that's mites that live on people's heads. It's sourdough bread, microbes that live in showerheads.

• 5:12Speaker 02

  But in the early 2010s, he worked with some colleagues to apply his rainforest ecology skills to house bugs specifically. It's a story that starts, fittingly enough, in a home.

• 5:23Speaker 03

  At the time, Michelle Trautwein, a very good friend, and her husband Ari lived just down the street from us. And so at the end of the day, sometimes they would just go over to their house, have a glass of wine, hang out.

• 5:33Speaker 06

  Wow, this is really going back to the beginning.

• 5:37Speaker 02

  This is Michelle Trautwein, an entomologist who specializes in flies.

• 5:41Speaker 06

  We had an idea that we were going to go into people's houses and collect all the insects and their relatives in a person's house.

• 5:50Speaker 02

  By relatives, Michelle means a whole bunch of arthropod species that aren't actually insects. So spiders, ticks, centipedes, millipedes, et cetera. Basically bugs. And while the word bug can refer to a specific subgroup of insects, throughout this episode, I'm going to be using bug in its more informal, sort of colloquial sense, to refer to this big group of all the creepy crawly creatures out there. So like, if I would use it in a sentence, Michelle and her colleagues wanted to collect all the bugs in people's houses. And they weren't actually sure what they would find. Like, in a paper that they eventually co-authored, they explained that modern Western homes were actually thought to be kind of sterile, without a ton of life.

• 6:36Speaker 02

  But since they didn't know of other comprehensive surveys of all the bugs in a bunch of human houses, they figured it was at least worth trying. So slowly, they worked together to sort of make this scheme into a reality. And also, these entomologists seem to just really love shouting each other out and giving credit. So I will just make sure to mention that Michelle led the field research with another scientist named Matt Breton.

• 7:01Speaker 06

  My good friend and colleague, who's like one of the greatest entomologists in the world.

• 7:05Speaker 03

  Sort of a entomologist, entomologist. He can ID small flies while driving past them.

• 7:11Speaker 02

  So Michelle, and Matt, and the rest of their team, decided to look at houses in and around Raleigh, North Carolina. They tried to sample broadly, looking at homes of people in various socioeconomic brackets. And they wound up looking at 50 houses.

• 7:28Speaker 02

  Michelle says they originally thought they would do more, but going to each house turned out to be a huge production.

• 7:35Speaker 06

  We had a whole getup. So we had kind of field vests filled with vials and forceps. We had nets, we had headlamps. And so even though we were going on these, you know, indoor, very tame expeditions, we looked like we were ready for the middle of the rainforest.

• 7:54Speaker 02

  Michelle, and Matt, and other entomologists working on the project, they would go into a house, they would collect data on how often it was cleaned, or whether insecticides have been sprayed recently, house pets, house plants, house layout. And then they would go hunting for bugs, sort of searching and collecting, sometimes for as much as seven hours.

• 8:15Speaker 06

  It's exhausting work. So a lot of it, it's like hands and knees along the kind of baseboards, window sills.

• 8:22Speaker 02

  They went under beds, they went behind toilets, and they used a tube to suck dust and grime into vials.

• 8:30Speaker 06

  It was an intimate, sometimes horrifying process.

• 8:35Speaker 02

  Michelle studies bugs for a living, but even she can appreciate that it is pretty gross to stumble across, for example, carpet beetle larvae munching on fingernail clippings.

• 8:48Speaker 06

  Like, ugh.

• 8:53Speaker 02

  But once they had collected everything they could, they took it back to the lab. And then they had to sort and sort and sort some more. Because it turned out that these houses were far from devoid of life. In fact, each house had so many arthropods in it that it was kind of shocking. Michelle remembers an ant scientist popping by for a visit. And when he saw a collection of vials from one house laid out on the table.

• 9:20Speaker 06

  He was like, oh, my gosh, you know, was this a house out in the woods that had, you know, left the windows open for years or something? And the truth was, no, it was a house in, you know, suburban Raleigh with a weekly house cleaner.

• 9:31Speaker 02

  And not only were there lots of bugs, but also the diversity of species was pretty amazing. Rob, for example, thought that he had a pretty good idea of the kinds of spiders living in his own home. As far as he knew, there were two species, a fat one and a skinny one. But then when the results came back from his own house.

• 9:50Speaker 03

  It would turn out it had like 11 spider species, including the spider species that just walks around and spits silk on things and only comes out at night.

• 10:00Speaker 02

  So they were finding all this cool stuff. And then after many months of work, they pulled all their findings together and were able to compare the diversity of bugs in each house. And these results were also surprising. Like, they found that in almost every house, there were about 100 different species of bugs, even if people were tidy or they sprayed insecticides.

• 10:23Speaker 06

  It seems like nothing made a difference.

• 10:25Speaker 02

  And this finding is actually roughly held up as Michelle and her colleagues have explored more homes all across the world. Like, some places do have a little more diversity or a little less the layout of houses or kind of the plant life outside can affect the bug life indoors. But the houses they've looked at always come with a wide array of insect roommates. It's like this whole hidden world kind of flourishing indoors just waiting to be explored. And it is a world that is worth exploring and understanding because they found that many of these bugs are not just sort of blowing in from outdoors, they're making themselves at home. They're forming ecosystems.

• 11:09Speaker 03

  And so there's a basement ecosystem, an attic ecosystem, a bathroom ecosystem.

• 11:15Speaker 02

  Rob says you can actually kind of draw a parallel between the ecosystem in a bedroom and the ecosystem on a forest floor. So on a typical forest floor, you'd find a bunch of dead leaves and then there would be bugs that would eat those leaves and then other bugs that might eat the leaf eaters. And in our bedrooms, humans are kind of like the trees and then our hair and our dead skin is like the leaves.

• 11:44Speaker 03

  So your body sheds tons of skin cells a day. The dust mites eat the skin cells. There are these other slightly larger mites that eat the dust mites, especially because the dust mites gather if they get dry into a little clump. And they're like wildebeest. And when they're there, these other mites eat them.

• 12:03Speaker 02

  And then something like a house centipede can come along and eat those mites. And the researchers also found that house bugs have the kind of weird, fascinating parasitic relationships that you see in the wild.

• 12:15Speaker 03

  For example, in many houses, we found this wasp that lays its eggs in the bodies of specific cockroach species. And it's teeny tiny. It's there carrying out this ancient ritual of laying its eggs and living babies of cockroaches, which they then eat alive. And it's happening all over North America right now. I mean, if you could hear it, you would hear the screams and the crunching.

• 12:42Speaker 02

  Now, at this point, you might be feeling disgusted or fascinated or, you know, like, an intense desire to never ever touch a surface in a house ever again. And if at all possible, to like, upload your consciousness into a computer so as to discard your, like, skin shedding, bug feeding corporeal form. And you may not be feeling any less inclined to view these parasitic wasp larvae and dust mite wildebeest as anything except kind of gross. But these studies are just the beginning.

• 13:18Speaker 02

  They show us how little we really know about the bugs all around us, like who they are and what they are doing. And figuring out answers to those questions, that's worthwhile kind of on its own, like, as Rob puts it.

• 13:31Speaker 03

  If we're going to understand any place on Earth well, it seems as though we should understand the place we spend 90% of our time.

• 13:41Speaker 02

  But also, Rob says that once we start exploring the bugs that are right under our noses slash under our beds, we can start learning from them and borrowing from them and like, maybe even finding ways to surround ourselves with better bugs that can help us lead healthier lives.

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• 17:32Speaker 02

  That's a bug. That's a bug. That is a bug. So we know that we are surrounded by bugs pretty much all the time. But what can we learn from them if we stop treating them only as pests and instead explore them like ecologists? To help answer that question, Rob told me the story of his work on something called a camel cricket.

• 17:53Speaker 03

  A camel cricket is a, it's like a cricket that is, that a cartoonist would draw. You know, it looks like a normal cricket, except its legs are too big and it's antennae, like they're like longer than the animal's body. People most often encounter them when they walk into their basement and it's dark and one of these jumps out because that's their defense, that they just jump straight into the air.

• 18:17Speaker 02

  In one of his many projects studying the home, Rob accidentally discovered that a species of Asian camel cricket had spread all across the eastern US and parts of the Midwest, almost unnoticed. And he thought this was kind of like wild and exciting, that a creature could literally jump out at people and still spread without getting spotted by scientists. It felt to him like a metaphor almost for how little we know about our own homes. And so, once again, he went to give talks about his new discovery.

• 18:49Speaker 03

  When I would talk to the public about camel crickets and houses, I was super excited. And so my enthusiasm is spilling over, I assume it's spilling over into the audience. And sometimes it was, and sometimes I would have people say, well, what good are they?

• 19:02Speaker 02

  History was basically repeating itself. Like, yes, Rob had made a whole career pivot from studying rainforests to studying homes. He was giving people the biology of their daily lives. But some of those people were still not sure how relevant his research was to them. And Rob did the same thing he'd done that first time around. Like, he listened to the people asking how this camel cricket could be useful to them, and he started to think.

• 19:29Speaker 03

  Okay, what good could they be? You know, what good to humans could they be? That's not their job, but, you know, maybe we can look.

• 19:35Speaker 02

  Rob started to think about what he knew about camel crickets, not as an annoyance to be eliminated, but as an organism to be studied. And specifically, he started to think about what was known about camel cricket biology.

• 19:47Speaker 03

  One of the things we started to see is that whatever it was eating, it was terrible, hard to digest stuff. It was bits of paint, bits of shoe, you know, bits of cockroach leg. And so that made it very likely that either it had gut enzymes that could break down those things, or it had microbes that could break down those things. What I didn't know is where that would be useful.

• 20:12Speaker 02

  Fortunately, Rob spends a lot of time talking to his colleagues.

• 20:15Speaker 03

  And so at that time, I bumped into Amy Grundon, who was an applied microbiologist in the building next to mine. Stephanie Matthews was a student working with her.

• 20:23Speaker 02

  I really was not lying when I said that Rob loves to shout people out.

• 20:27Speaker 03

  And at the time, Amy was working on black liquor.

• 20:29Speaker 02

  Black liquor is a waste product that comes from making paper. And it has a bunch of stuff in it that is hard to break down, so it's often burned or dumped into rivers. Which means that Rob was looking for something that camel cricket guts might be able to break down, and Amy had a weird thing that needed to be broken down. So Stephanie Matthews, Amy's student, wound up looking for microbes in camel cricket guts that could break down the stuff in black liquor.

• 20:57Speaker 03

  And long story short, she found them. And so she basically found, in the first individual camel cricket she studied, one camel cricket for science, microbes that could break down black liquor and turn it into energy.

• 21:12Speaker 02

  Right now, Rob says it's still cheaper for paper companies to dispose of things in other ways. So the industry has not adopted these microbes yet. But still, researchers travel to the rainforest looking for insects and other animals that could produce useful compounds. And research like this shows that the creatures living much closer to home could offer similar insights if we, you know, paid attention to them instead of trying to find ever more inventive ways to zap them out of existence. In fact, the pesky ants that people wanted to eliminate from their kitchens, they're another example of this.

• 21:48Speaker 03

  People who actually study ants in detail know that ants produce their own antibiotics, and some species grow bacteria on their exoskeletons that produce antibiotics.

• 21:59Speaker 03

  And so in studying some of the most common ants we find in houses, Omar Halaani, who was a master's student, was able to show that those ants have some compounds that their bodies are producing that are highly antimicrobial, including against some species that are problematic pathogens of humans. And so that was just, you know, it's a small study, but it, but it, the potential there is great.

• 22:24Speaker 02

  Rob also sees potential beyond just like studying house bugs for cool bacteria or antibiotics. He thinks that if we learned more about the bugs around us, we could potentially change the bugs around us by bringing in more helpful bugs.

• 22:39Speaker 03

  What would it look like to, to manage our houses to favor species that benefit us?

• 22:45Speaker 02

  It turns out that people around the world are already doing this.

• 22:49Speaker 03

  Both in South Africa and in Mexico independently, people discovered that they could bring these webs of social spiders into their kitchens. And the spiders would eat their flies. And it would also reduce disease transmission. And so in two separate, totally unrelated cultures, different social spider colonies were brought into the home to have this control effect.

• 23:13Speaker 02

  I kind of think of this as like pest control from an ecologist's perspective, where you figure out what all the bugs in your home are up to so that you can encourage the beneficial ones and use them to keep the annoying ones in check. And actually, this approach might end up being more effective than constantly trying to kill everything. Like, there's a species of jumping spider that specifically loves to feed on mosquitoes right after they've sucked up blood, including blood that's carrying malaria.

• 23:45Speaker 03

  And so that spider eats the mosquitoes when they're most dangerous.

• 23:49Speaker 02

  So these are spiders that you might want to have around.

• 23:51Speaker 03

  But one of the things people have seen is if you go and then spray that house with pesticides, it kills. All the spiders.

• 23:58Speaker 02

  It does also kill the mosquitoes that were in the house. But eventually, new mosquitoes fly back in, looking for blood. And the spiders don't necessarily return with them. Which means by trying to achieve a totally sterile home and blanket spraying pesticides, a homeowner might actually eliminate a potential line of defense against the very creatures that they were worried about. So Rob doesn't think that we should never spray pesticides, especially if someone has a huge infestation of something.

• 24:31Speaker 03

  I'm not against pest control in houses.

• 24:34Speaker 02

  But as Michelle and Rob's surveys of houses show, the dream of a perfectly sterile home without any bugs at all just isn't realistic. And when we overspray or overkill, we're not doing ourselves any favors.

• 24:48Speaker 03

  And so how do we think about, you know, we're not going to stop using pesticides, but using pesticides in the most controlled ways so they kill what we want to kill, while also not killing the species that are helping us? And in crops, you would call it integrated pest management. We don't have a word for it in houses.

• 25:07Speaker 02

  But Rob says that if we want to do a kind of integrated pest management for houses and do it well, we need to do a lot more exploring first. Like, we need to know more about who to invite in to find species like these helpful spiders. And we also need to know how to invite them in, like, how to help them thrive. And Rob has had conversations about what that might look like, but...

• 25:31Speaker 03

  It reveals our ignorance, because it reveals the fact that, like, we don't know enough about what these species do for us, and we don't know enough about what they need and how they move among buildings. We don't quite have enough information yet.

• 25:48Speaker 02

  And honestly, maybe it's OK if we have a ways to go before we start managing our household bugs. Because I know I could use a little time to get used to this idea. Like, I actually first found Michelle Trautwein's research because I was reading up on a really frustrating beetle that had invaded my home and ruined a bunch of my stuff and kind of ruined my life for a few months there. So like, I'm not sure I'm ready yet to actively invite more bugs into my home. That being said, just talking to Rob and Michelle, I'm a lot more comfortable with the idea that there are probably a bunch of bugs fairly close to me right now. And

• 26:32Speaker 02

  it's actually kind of nice to think that, you know, if I got to know them a little bit better, I might find that some of those bugs are actually pretty good roommates.

• 26:50Speaker 02

  If you want to learn more about the bugs close to you right now, I recommend digging into Michelle Trautwein's research and also reading Rob Dunn's excellent book, Never Home Alone. It'll also explain why the International Space Station smells kind of funky. It's a very enjoyable read. And if you want to help researchers who are doing this work, go to inaturalist.org and look for the Never Home Alone Project. That'll let you upload pictures of species in your home so they can be used for science. And we would also love to see the bugs in your home. Like, if you send pictures of bugs into [email protected],

• 27:31Speaker 02

  you'll make my day, but we also might share them on Twitter or a piece on the site, potentially. So, [email protected], send me pictures of bugs. And now, it is my turn to act like an entomologist and shout out my colleagues. So, this episode was reported and produced by me, Bert Pinkerton, but it would not exist without the editing that was done by Catherine Wells, Meredith Hadnot, and Brian Resnick. It would not sound nearly as good without music from Noam Hassonfeld, or just the incredible sound design work that Christian Eyal does week after week. Like, seriously, Christian is just like a wizard with sound,

• 28:12Speaker 02

  and the whole world should know. Neel Dhaneshia helped me think through the outlines of the episode, and Manning Nguyen makes me laugh, which is arguably the most important and helpful thing of all. Unexplainable is a part of the Vox Media Podcast Network. We will be back on Wednesday.

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  At Edward Jones, we believe rich is more than caring about the latest and greatest. It's also taking care of what gives your life meaning. That's why your dedicated financial advisor meets you where you are with personalized financial strategies that help protect what matters so you can preserve your progress while creating a path forward. The key to being rich is knowing what counts. Let's find your rich together. Edward Jones. Member SIPC.