A caterpillar that haunts spiderwebs, solving the last riddles of a famed friar, and a new book series
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This is a science podcast for April 25th, 2025. I'm Kevin MacLean filling in for Sarah Crespi. First up, staff writer Eric Stock said join Sarah Crespi to talk about why 21st century researchers are still interested in Gregor Mendel's peas. They also cover a couple other recent plant stories, including why wavy fields might be more attractive to insects and a tree that benefits from being struck by lightning.

Next on the show, entomologist Dan Rubinoff joins me to talk about a carnivorous caterpillar that haunts spider webs, camouflaged in its insect-praised body parts.

We discuss how such an adaptation might have evolved and the overlooked importance of insect conservation. And finally, we kick off our 2025 books series. This year's theme is the science of death and dying, but the conversation is surprisingly lively. And how could it not be with books host Angela Saini and books editor Valerie Thompson, right? They talk about the challenges of putting this year's list together and the reads they're looking forward to.

Now we have staff writer Eric Stockstead. He wrote this week about identifying genes in peas. These are pea plants. Identifying genes for traits that were written about way back in the 1800s by Gregor Mendel.

And after we get through with Mendel's peas, we'll talk about some of the other stories Eric has worked on in the last month. Hi, Eric. Welcome back to the show. Hey, Sarah. Great to be here. So, Eric, can you remind us who was Gregor Mendel? Gregor Mendel was one of the key figures in the history of genetics.

He worked as a friar in what is now the Czech Republic in the mid to late 19th century. He was a generally curious man. He was educated at the university.

and then took a job at the Abbey, partly because it gave him time to do his experiments and his observations. He was a meticulous observer of the weather. He was a passionate beekeeper and studied his bees. First person to describe a tornado in Europe. So, General, all-around fascinating scientist.

But he's famous for discovering mathematical patterns and laws of inheritance. Right. This is where the peas come in. This is where the peas come in. So he ordered pea varieties from seed catalogs. And then he started experimenting with the different traits that he could easily measure.

the color of the flowers, the size of the peas and the shapes of the peas. And what he did was he crossed these. So he took pollen from one pea variety and pollinated another pea variety. He then watched

or measured and wrote down what the traits were in the offspring. And he did this for years, year after year, eight to 10 years, thousands and thousands of pea plants. And then because he had studied math, he realized that there were interesting patterns

in the statistics of how frequently these different traits showed up in the progeny, the F1 and the F2. He realized there was a one to three ratio of traits in the first generation. And then in the next generation, there was a different ratio. And this had to do with

the inheritance of recessive or dominant alleles. An allele is one variation of a gene. It can be dominant or recessive. Right? This is all coming back to our listeners. Exactly. Exactly. So if you've ever had to do like a Punnett square where you have to work out the probability of a trait appearing in the next generation, this is the basics behind that. The Punnett square came later, but the math is still the same. And

And Mendel, he did an amazing job of observing and asking questions and carefully showing the math behind this. Mendel was looking at peas and he was calculating the probabilities of inheritance and he figured out things about dominance, dominant and recessive genes.

But what he didn't do, because he couldn't, because it was so long ago, was actually identify these genes, what their actual function was in the pea plant. You got to fast forward quite a while in time to be able to do those kinds of experiments. And it wasn't until this year that every single...

trait that Mendel analyzed or have been identified in pea plants. So why did it take so long? So several things going on. The first of these traits, and it's the classic one, right? The round versus wrinkled pea. The genes behind that were identified in 1990. So the first one was discovered quite a while ago. And since then, other genes have come to light. But

It's really, I think, you know, two major things here. One is that the pea is not exactly an orphan crop. There's less money in pea farming than there is in corn farming, maize farming, or wheat or rice. Pea is a smaller crop.

So it makes sense that the investment in sequencing the genomes goes towards the economically large high volume crops. The corn genome was sequenced 2002, I think, and it was only in 2019 that the pea genome was sequenced. That's one factor. And the pea genome is big.

It's larger than the human genome. If you were trying to do this 20 years ago, it would have been a big task. Incredibly expensive and time-consuming for something that isn't necessarily top crop. Right. It's accelerating. This is getting easier and easier. So 2019, the first, the P genome is sequenced for the first time.

And more work has been done since then. So what have they learned through this accelerated research into peas? If you sequence the genome, you're sequencing the genome of one pea. And that pea is either going to have round seeds or wrinkled seeds. It's either going to have purple flowers or white flowers. So it's going to have one or the other of these alleles.

If you really want to get a handle on the genes and the genes behind the diversity of traits that a plant has, you need to look at a range of types of plants. They have to do what Mendel did, where they had to order stuff from a seed catalog.

and then compare them to each other. What they do is they go to, I don't want to say the Amazon of seed catalogs or the Sears Roebuck for the rest of us. They go to a gene bank. Yeah. They go to a place that holds thousands and thousands and thousands of seeds of different species, different varieties of the same species. And

They sequence as much of the DNA as they can for each of these, and then they can compare between them to find genetic patterns that correlate with the different physical traits of the plants. We don't know exactly what varieties Mendel worked with from the seed catalogs of the 19th century, but you can get pea plants with the same trait.

So more and more of this is happening. And in this latest paper, they've now done the largest such sequencing effort, looking at nearly 700 kinds of pea plants. Most of these were stored in an institution in the United Kingdom where scientists had gone in the early 20th century to the Middle East where the pea plant was domesticated 10,000 years ago and brought back as many different types as they could.

and to other regions of diversity around the world for people. They sequence these 700 varieties and they can compare them with the traits that Mendel looked at, these seven traits, but also dozens of other traits that are important for farmers. Yeah. Does it taste good? Does it get to the right height that I like? All that stuff.

agriculturally important traits. And then, you know, through a process of mapping and further experiments, they can narrow in by making this genomic map of peas on where the genes are for these traits. Traits like the wrinkled or

round. Those are still of importance to breeders because it determines how much starch or sugar it is, all the vegetable peas that we eat. So those are one of those traits. That's the recessive trait for this wrinkled round gene. And if you buy a bag of split peas to make soup out of, that's the other kind. Is the pea flower color useful?

So any commercially grown pea plant is going to have white flowers because the same gene that gives the color purple to a flower will also make the peas and the pea pods have an undesirable taste. What other genes were they looking at that also had agricultural relevance? Most of the traits that plant breeders are working on now to solve a challenge, to create pea plants that are resistant to disease,

or to create pea plants that really are higher yielding or that can tolerate heat or withstand drought. A lot of these traits, they don't follow this pattern or they're not as clear cut.

as what Mendel studied. What's really astonishing about what Mendel did as a scientist is that no one knew what genes were. No one knew what the physical basis of inheritance was at this time, right? Darwin had an idea. He was mostly wrong. Mendel didn't know either, but he figured out a pattern.

right, that put us on the path to understanding how this all works. And Mendel was looking at genes where the alleles have a clear, unambiguous signal. You inherit one gene, we'll make a plant this way or that way, and you can write down in your notebook what it was.

For drought tolerance or yield, it's much more complicated because many, many genes are involved. And it's the sum of all those different alleles and all these different genes that makes it more or less of a bountiful harvest. Mendel wasn't looking at those traits because they were too complicated. Many of these important traits that plant breeders are looking at now, right, that they're trying to solve are those cumulative, we call quantitative traits.

traits. So the forefront now really is beyond what Mendel could have figured out at this time. But I think he celebrated for the clarity of his experiments, the clarity of his thinking that he was able to find a system that worked and come up with these patterns. Yeah, he planted the seeds. Yeah, he planted the seed. There you go. All right.

That's it for pea plants, Eric. But as I mentioned up top, there are a few other things to discuss. I've been watching your reporting and you've had some really interesting stories. What's this about? What is it? Mowing or tilling your soil in curvy lines can help your farm? What's that? You know, that was also a very elegant experiment.

I get so much pleasure out of learning about these experiments where people do clever investigations. So it's very artful. And in this case, right, it's almost like farm art.

I don't know if you remember the photo from that. It was of these wavy, right, wavy tractor lines. Right. In the photo, you can see that the edges of the field are wavy. What is this about? It's about habitat. How can you make habitat for insects in an agriculturally managed landscape? Insects benefit when the grass is of various lengths, not all cut to one mower height.

And so if you go through three times and mow and you eventually get all the hay, but you leave the grass at different heights, then that's good for insects because some of them like to lay their eggs in grass that has stems a little bit longer and dry.

What this experiment looked at was whether the shape matters. So this is wavy in the other direction, not just wavy up and down, but wavy side to side? There aren't a lot of rectangles in nature. Yeah. And most farmers who have rectangular fields will go in and they'll mow one rectangle at a time. They'll mow one third of it and leave the other rectangle.

So this was an experiment to mow wavy lines. You mow a blob shape rather than a rectangle. The idea being that there might be something about that shape, which is more natural, that would benefit pollinators. So they had some farmers mow a blob shape that was exactly the same area, the same amount of hay as a rectangle. Oh, amazing. Right? So...

And what they found was for certain pollinators, this did matter. And they would come back every third of the season and mow a different shape blob so that they're pulling out the same amount of hay, but you're getting a different shaped patchwork. And they find that that benefits them. It's like, you know, like a bunch of cows wouldn't eat the same rectangle or a bunch of bison or deer wouldn't eat the same. But it is like...

Oh, the duck's like my kidney-shaped pool more than my square pool. I haven't seen that one yet. All right, Eric, next one. Ready? This one? Okay, well, this will be the last one. This is why some trees don't mind getting struck by lightning so much. Like many people. Maybe not your dog. Many people...

Like lightning, right? I mean, it's a dramatic lightning show. Seeing a Midwestern lightning thunderstorm, right? But nobody likes to get hit by lightning. And the obvious thinking is trees don't like to get hit by lightning either. And it's not going to be a good thing.

And in more temperate forests, that's certainly true. Lightning will kill trees. It will strike the tree and leave a big lightning scar down the side, and that might eventually kill the tree or immediately kill the tree. Some trees will explode because of the oils in them if they get hit by lightning. Oh.

all sizzle and get hot at once. Turns out that's not true for some species in the tropics. And that's what this new study has demonstrated is that certain species in tropical forests, and this research was done in Panama, seem to benefit

from getting hit by lightning. And one direct benefit is that it will kill these vines that live in the trees. These vines are parasitic in the sense that they grow over the tree's canopy so that they are stealing light from the tree. Thanks for the boost up to the sky. Now I get all the light and you get nothing. And eventually...

The vine getting all the light and the tree getting nothing is bad news for the tree. Yes, it's been shown that trees that have severe infestations, they flower less. What this study found was that these tropical vines called lianas, they will get blasted by the lightning strike that hits the tree and they will suffer more than the tree does. This species of tropical tree will get only minor leaf damage,

But a year later, the researchers come back and they see that the vines are dead. Yeah. So that's a benefit to the tree. They also found that the lightning somehow will pass through

through the tree to neighboring trees of other species. And it will damage those neighboring trees more than the tree that actually got hit. What's so special about this tree? Like, why is it able to kind of not only withstand this, but pass this lightning off to others? It's called the Elmendro tree. And we don't know for certain, but one of the ideas for why it might survive lightning better is that it can conduct

electricity. So it's not going to heat up when the surge of current goes through the tree like other plants do. It will conduct the electricity down into the ground. There have been studies of different types of tropical wood and the almondo tree has a

type of tissue that may conduct electricity better. That's super interesting. Yeah, I really like the way they did this experiment. They just like watched the tree to see who got stuck by lightning and then looked at the survival. And they found that this one was not only better than the other trees, but that it was its neighbors were severely harmed by it.

being near it. It's actually surprisingly hard to tell where lightning hits. So they installed several monitoring systems that would allow them to narrow down where the tree was. Because if you're trying to find a tree that survives lightning and doesn't look damaged, right? And that may be why there were so few studies of this in the past. Yeah. I mean, because you can see from space that lightning has hit the earth, but it doesn't tell you which tree it hit if you're going off

Right. So if a tree is hit by lightning in a forest and doesn't get damaged. We'll fill in the blanks from there, Eric. All right, Eric, we're all done. Thank you so much for talking with me. Fun chatting as always. Eric Stockstead is a staff writer for Science. You can find a link to the stories we talked about today at science.org slash podcast. Stay tuned for a conversation about the bone collector caterpillar.

The animal world is full of species finding dangerous ways to survive. Just a little while ago we had a news story about a fish that hides in the shadow of a shark to surprise unsuspecting prey, and there are plenty of other examples of creative camouflage to help animals blend in with their surroundings. I'm endlessly impressed by those praying mantises that look like orchids, or those patoo birds that look up in the air and blend in like tree stumps.

A caterpillar in Hawaii is doing this pretty skillfully. These tiny caterpillars, like smaller than your pinky nail, also flirt with danger a bit with their disguise. Dan Rubinoff is here to talk about the bone collector caterpillar, a predatory and sometimes cannibalistic caterpillar that lives on spider webs, blending in with a coat of dead insect parts.

Hi, Dan. Welcome to the Science Podcast. Hey, Kevin. Thanks for having me. Great. Well, it's so nice to have you. Now, tell me, how did this whole thing get started? Did you just notice something weird on a web when you were out surveying? I wish I could say I was that perceptive, but it took quite a few introductions before we figured out what was going on. The caterpillar is part of a big moth group here, Hyposmocoma, the Hawaiian fancy case caterpillars.

And most of them do pretty innocuous things like graze on lichen, maybe detritus, that kind of thing. And so we noticed as we were digging around for ones that we knew about, that there was this sort of

Looks like a slot of bug parts sitting next to spider webs when we were tearing through logs looking for other members of the Hawaiian fancy case caterpillar group. And eventually we started to realize that there was a caterpillar in there, which was again years in, but we were incredulous. Like this doesn't make any sense. And you keep thinking it's got to be an accident because it is so absurd looking. There's a spider web and then next to it is basically a jumble of sewn together bug parts.

It's one of the weirdest things I think I've seen in nature, honestly. After a while, we started realizing these were caterpillars. We started growing them. We didn't find them very frequently. And it kind of makes sense that they're not that common because it is, as you say, a very precarious lifestyle. I mean, talk about living in the lion's den. You're literally eating the lion's prey under its nose and just hoping it doesn't notice.

Yeah. Tell me about this spider. Is it just very tolerant or is the bone collecting behavior like literally what keeps the caterpillar alive? Well, it's kind of incredible because we have only found these caterpillars now on introduced invasive spider species. We haven't detected them with native spiders. And part of that is because native spiders are so uncommon in these logs. So it's

It's really typical and sad, but in Hawaii, a lot of native species are gone. And that includes the insects. I think to some degree that hasn't really been appreciated as much. Extinction in plants is really well known. Extinction in the birds is infamous. But the insects have suffered, we think, at least as much. And one of the crazy things about this caterpillar is it's holding on in one mountain range on one island in the custody of these introduced spiders.

And so if it couldn't handle introduced spiders, it would be gone. But yeah, the spiders don't seem to notice. And I think it's because, again, I can't read spider minds, but I think it's because these caterpillars are covered in their body parts, right? The shed body parts of the spider and the prey. And they move so slowly that I think it doesn't really trigger a response. And then the webs that the spiders are spinning in these logs or tree hollows

are probably not sticky enough to these caterpillars that they're getting caught and struggling. And so that seems to be part of it. And also the cases, I think also help. So if the spider were to say, try to attack it, it would have a tough time getting in there. Having said that, we have never seen one of these caterpillar cases spun up in the spider web. So you see body parts of earwigs,

termites, you know, I could go on and on. The spiders are eating anything they can catch in there and the caterpillars are taking their body parts and decorating their cases with it. But I think it's just a case of the spiders not recognizing it that way. And it's kind of cute because they will try to size the insect body parts that they attach to their case, but some of them are not good at it. And one that we got recently had pretty much half of a dried up earwig attached to it, which was

at least as big as the cage itself and just looked absurd. And yet you think about it, and it's like, I can see how a spider living there might really be fooled by that because they're going to think, oh, I'm going to grab this, but their first sensory experience is going to be a dried up husk of half an earwig.

And they're immediately probably going to discard that and think, oh, I must have been seeing something. This case couldn't have been moving. Yeah. And so there's a few things that are unique about this behavior, right? It's a carnivorous caterpillar. Is that a very common thing to see? Incredibly rare. Thank you for asking. That's one of the things I've said in the past, it's kind of like having a vampire cow. It

It's that unusual. But Lepidoptera, the butterflies and moths, are one of the most diverse orders on the planet. If you look at groups, there are more of them than there are any group of vertebrate that you can think of. And 200,000 species of moth and butterfly have been described, and I'm sure the number is much higher than that when we actually get to work on a lot of these little moth groups.

and yet 0.13% of them are carnivorous. Not 1.3%, but 0.13%.

So globally, carnivorous caterpillars are basically non-existent. If you're looking for them, it would not be something statistically that you would be able to find. And yet in Hawaii, we have at least three different unrelated groups of caterpillars that have gone carnivorous. Yeah. And now this is the first time that this kind of behavior has been documented, right? Yeah.

- Absolutely, yeah. And that's why, again, it took us a long time. The first time you see a Caterpillar case covered in body parts, you think it's an accident or a coincidence. Oh, this dumb Caterpillar is building his case and fell into a pile of debris. And so everything on it had to be that way.

After the 15th or 20th time, you know, I finally start to get the message. Oh, no, no, they're doing this on purpose. And they're hunting these kinds of things down, literally crawling around in that log next to the spider web, discarding other things and only using insect parts because they're

There aren't a lot of insect parts around the spider web, believe it or not. If you look in there, you're not seeing a sheet of them underneath. It's not like smog's lair where there's bones and skulls lying around with the treasure. There's very few little insect parts. And so they hunt. And when they find them, they pick them out.

feel them around to make sure they're the right size, maybe chew on them a little bit, and then weave them onto their backs. The closest thing I can imagine might be you see hermit crabs doing some kind of crazy stuff too, where they attach stuff to their shell very meticulously.

So that's what the caterpillars are doing. And it's just not the kind of thing that you would bumble into. It really has to be something that's evolved. You got this reward, right? This larder of food that's just sitting there that you can kind of sneak in and eat. But if you screw up or, you know, your case isn't thick enough or you haven't put enough stuff on it, uh,

you get eaten. And you can imagine the selection was probably pretty strong. If you're living next to a spider web and you're not good at decorating your case, you're more likely to get eaten. And so those guys get weeded out of the gene pool pretty quickly. And so you end up with these very particular caterpillars doing very particular things.

Oh, interesting. So you said this is an introduced spider species. Do you think this is a behavior that has come up since that spider was introduced? Or is it something that probably existed with native spider species in the past? Well, the crazy thing is so far, I think it's five different spider species all introduced that we found these caterpillars associated with. So I don't think they're gunning for a particular spider. I think they're gunning for a particular environment.

Like, give me a spider web, a little cobby spider web in a corner or in a log, and I'll live there. That's what they're looking for. And these invasive spiders are now providing it and may honestly have out-competed and exterminated the native spiders.

I don't know that. It's just we see that kind of pattern in a lot of different things. Ants come in and the native insects get wiped out. So in this case, it wouldn't surprise me at all if these invasive spiders have come into these logs and these crevices and out-competed the native spiders that were there. And the only reason that this bone collector caterpillar has survived is it has that flexibility. It's able to jump to these invasive spiders. But

I can imagine it probably doesn't care because it's already a particular enough situation. Being in a web, in a log, or in a tree hole like that, to be able to identify the exact spider species and depend on one would be a really tough chore, even if it was just native spiders, I imagine.

Yeah. So after you've observed it a handful of times out in the field and you see it again and again, like what do you do now? Have you been able to bring them into the lab and observe the behavior there as well? Yeah. I mean, that's the first thing we do is when we find these things in the field, we bring them into the lab and try to rear them. Fortunately, we'd had experience with other carnivorous caterpillars in Hawaii. So we knew to sort of try that as well with these guys.

And they're actually not that picky in the lab as to what they'll eat. So we have these flightless fruit flies and we bonk them on the head and drop them in with these caterpillars. And then the caterpillars are happy to eat them. So they're quite agreeable in that way, but they won't put anything else on their case except for body parts. So if we didn't have

insect body parts in the container with them, their cases sort of start to get depleted of those kinds of things. And that was kind of interesting to discover as well, is they won't compromise. If you give them something that's a bit of flog, a

a bit of rock, you'd think, you know, another Hyposmocoma will incorporate those kinds of things sometimes. But this species is really picky about what they put on there and probably with good reason, right? As we talked about, the ones that aren't picky probably got eaten. Yeah, so they do have to get really good at this adornment that they're doing. People have asked, do you ever see more than one in the same spider web? And...

When I said that they eat anything, they eat anything. And we have a video up showing a bigger one chewing a hole in the case of a smaller one and eating him alive. So they are not good members of their community. They're definitely predatory, as it were, in that sense. So you end up with relatively few or dispersed numbers of these animals. If you find one, you're not going to find another right next to it.

What else do we know about sort of the evolutionary origins of these types of species? So we know that Hyposmocoma is a very old group in Hawaii. And that is because, well, one, they're found nowhere else. And it's a little bit hard to understate how remarkable they are in that way. They represent one third of all the species of butterfly and moth in Hawaii are in this genus Hyposmocoma. It's pretty crazy.

In fairness, there are lots of other species that need to be described in these other groups, but also Hyposmocoma has a bunch more. There are over 350 species in the group. And we think from previous work that they're probably about 14 million years old here, which means that they arrived or their ancestors arrived in Hawaii before any of the islands that are currently up or even a twinkle in Pele's eye, right? The islands they arrived on were things like Gardner Pinnacle, which is now just a little sea stack.

But 14 million years ago, might have been 9,000 feet tall. And so that's kind of a little bit of a mind bender. But we forget that there was a party going on here long before the current islands were up. And a lot of these lineages, these animals' histories are older than the islands that they live on. So what is the rest of the life cycle of this species look like? You said that it becomes a moth. Is that moth something that you would see more frequently than the caterpillar itself?

In some cases for this group, Hawaiian fancy case caterpillars, we find the moths much more often than the caterpillars, but mostly we find the caterpillars more. And that has to do with the moths being sometimes not strongly attracted to the sort of classic black light traps that we use or being diurnal, flat out, just not flying at night. I think

If we've seen adult bone collector caterpillars, it's only been in the vicinity of these micro habitats where they are living. And the other funny thing is when you catch the moth, there's no indication that it's doing these crazy things as a caterpillar. And so we might've caught them before and sequenced them and thought, oh, they're related to this other clade of crazy carnivore caterpillars in Hawaii, but we have no idea what they do. There is nothing like them. And I think

That's maybe one of the more poignant things about these bone collector caterpillars. If you can call something doing gruesome things like this poignant, there's only one species that we found. And this is in now my 23 years of working on this group specifically, but also over a hundred years of other entomologists collecting and looking for things like this. We've only found them in a few parts of the Wai'anae mountains on Oahu. They are not on any other island. And again,

Obviously, they must have been on Kauai beforehand because Kauai was up before Oahu and they would have needed to probably jump down.

But we haven't been able to find them there. And it's probable at this point, since I'm not saying we're perfect, but we've been doing this for a while. We're pretty good at finding things. And if we're looking for these, we should have found them. We think they're gone there and they aren't anywhere else. They aren't even in the Ko'olau Mountains on Oahu, which doesn't make sense because they're pretty close to the Wainais. Oahu isn't that big. And yet they aren't here. They're just in those Wainai Mountains. To me, that says that this is sort of

I don't want to say a relictual species, but one that's just hopefully not winking out, but just holding on at this point. And that is a little bit disconcerting because it's so remarkable.

Right. Yeah. There's a lot of crazy things in Hawaii, but this one is really taking it to a new level. Yeah. I mean, just with how rare it is and, you know, it's very limited geographically. Are you concerned? Like, do you like keep these locations under wraps or is that even a concern or anything like that?

Well, the commodities market in fancy case Caterpillars has been fairly limited so far. So we haven't been worried about people coming in. Maybe after this blows up, we'll be getting, you know, those fans. But fortunately, in that sense, I haven't had much concern. They are hard enough to find, too, that it's not something a casual person would be able to sort of find easily.

Anyway, I'm mostly concerned about the habitat degradation. And I would say for almost all Hawaiian insects, that's the major threat is the loss of habitat, not just through plant species disappearing, but through invasive species coming in, specifically invasive insects wiping out the native insects. I think that has done a real number on the native insects in Hawaii. And that's not something that's easy to control. It's not a snap of the finger sort of decision. You can't pass a law and say, hey, listen up, ants.

don't come in here. And so we end up with a really challenging situation where it is hard to conserve them and they are only in a few spots. Yeah. So what's next for this work you've published? We'd like to look into the sensory evolution to try and understand how they perceive things. How are they detecting something like a body part amongst all the detritus floating around in a rotting log? How do the female moths detect the spiders and get close enough to them?

It's probable that they're not getting very close in part because of how dangerous that would be. And in part because crawling through the interstitial areas of a rotting log is hard even for a small moth. My guess is that they are flying around in areas where these spiders are common and then laying their eggs and counting on their little caterpillars to crawl in and sort of pick up on the cues that they're near a spider web before they camp out.

So I think that's probably what's going on there. But I guess in this time of questioning science and its broader value to society, I would just sort of emphasize that we don't make planned linear discoveries. Things happen because we're looking, not because we're looking specifically for something. And so right now we're talking with a colleague about looking at the sensory systems for these insects because they're

It'll help us understand them better, but it might have broad implications for everything from pest control and how pest species recognize our crops to even something like AI and teaching that recognition things. So that's, I think, going to be a really interesting venue for understanding these caterpillars more. And we're also interested in looking at the genomics. Their sister group is also carnivorous here in Hawaii, but they separated about 5 million years ago.

And that other group eats live prey. Some of them hunt snails here, tree snails here, and spin them down and eat them. Other ones hunt other fancy case caterpillar species and eat them. And so they're doing some nasty stuff too, but they don't live in spider's webs and they don't decorate their cases like this for their own protection. So in the last 5 million years, since these guys split, which is around the time Kauai was bubbling up,

They have gone on very different paths and understanding those differences even would be pretty interesting, I think. Yeah, great. Well, thank you so much, Dan. It was great to have you. Oh, it's been a lot of fun. I appreciate you being willing to talk about this group with me. Yeah, of course. Dan Rubinoff is a professor of entomology at the University of Hawaii. You can find a link to the paper we discussed at science.org slash podcasts. Don't go anywhere. We've got a preview of our 2025 book series next.

This is the kickoff for the 2025 book series. I have our books editor, Valerie Thompson, and our books host, Angela Saini. We're going to talk about this year's theme and kind of what went into putting this together. So Valerie, what's the theme this year? I love this year's theme. And I was thinking about how funny it is that last year's theme was a future to look forward to.

This year we're doing the natural sequel. We're doing death. So science and death, you know, the future we're all looking forward to. We're all looking at, even if we're not excited about it.

Exactly. I just also wanted to point out that we did decide on this topic in October of last year, but it does still feel right to be thinking about confronting existential threats. Absolutely. Angela, did you kind of think this was going to be a downer? Finding six books on the topic of science and death might be a little daunting.

You know, the weird thing is it's become a really hot topic within the sciences. So there have been loads of books lately looking at ageing, longevity, but also how we imagine death and that kind of thing. And I do wonder if it's partly to do with the fact that we're all living so much longer, but however long you live towards that end point, you naturally start thinking about death, right? Everyone kind of considers their mortality. And so I wonder if it's just a demographic thing as populations age and

We all ruminate on this, and that's why maybe there's a spate of so many books on this topic. So, Valerie, one thing that we always try to do with our book series is to keep it broad in terms of covering different types of science. That was kind of a challenge for this book series.

Yeah, I think like both of you kind of hinted at this. There's a rich kind of realm of inquiry for science in this area. And so we can look at it from a lot of different ways. You know, the straightforward biology of death, sociological examinations of death practices. And then we kind of took it a little liberally, too, and decided to look at the astrophysics of how the universe itself might end. So it'll give like a real rich breadth of topics for the series to explore.

Definitely. I just want to say, yeah, that I have been very impressed at us in managing to get such a breadth of different disciplines because it would have been very easy to just focus on medicine and biology. In fact, we could have populated this entire list just by looking at medicine, but we really didn't. We looked at anthropology, history, philosophy, technology, as well as astrophysics. Right at the end, we kind of land on how might the cosmos end. So

So we're looking at death in its very, very broadest sense. So not just the actual moment of death itself and what happens to your body at that moment, but also how we imagine it. How do we think about this existential end and how differently do cultures approach that? Which

Which is really powerful, I think. And I think even biologists who work on this topic, and I noticed this when we were looking at Venki Ramakrishnan's book, Why We Die, The New Science of Aging and the Quest for Immortality, that he also ruminates on the

philosophical aspects. You know, why are we preoccupied by it? So everything goes hand in hand. The biology is there, but also the philosophical bits. Death has a huge impact on our lives from every level, especially socially, culturally. So I'm really glad that we managed to get that in there. Yeah, I think these intersections too are so interesting. I mean, they're interesting for

practicing scientists to think about these more philosophical questions. I think that comes up a lot in Tamara Nese's book, Death Glitch, where she's talking about how tech designers didn't really think to consider death in their designs, how users are eventually going to die and how they're going to be memorialized online. These topics are just naturally very interdisciplinary. And when you start pulling from different disciplines, it becomes a very interesting conversation.

Absolutely. And I just want to highlight, too, that we're going to talk about a book that covers how animals think about death, which I'm excited to hear that interview. I haven't heard anything yet, but I'm just like, wow.

There's this really lovely Scottish fable. It might be a true story, I don't know, but I grew up with it, called The Tale of Greyfriars Bobby, about a dog who, when his owner died, would go to the graveyard all the time and just wait there. And lots of people have stories like that, right, of very loyal animals. But what's interesting about Playing Possum, which is Susanna Monceau's book, she's a philosopher, is that she's looking at the very different ways in which various animals think about death. So it's not just about that

loyalty or that love but it's also there are chimps who grieve dead ones or possums and the reason she titles her book playing possum is because possums sometimes pretend to be dead and

So that's why we use that phrase, which is fascinating because it means that somewhere in their imagination that then is this idea of what a dead possum looks like. Unappetizing. Well, it depends who you are. It depends if you're someone who's interested in eating them or not.

And the other one I'm really excited about is the history book that we're covering, because when we talked about your book last year, Angela, and we dug deep into the past and talked about this like history of patriarchy, I just was like, I forgot how much amazing access we have to the past now and how much we know. And we don't think about it enough. Yeah, absolutely. And if you go to

to history museums, if you go to the British Museum or the Smithsonian, for instance, you will see a lot of how cultures in the past, ancient cultures, thought about death. You know, you look at ancient Egyptian tombs, you look at mummies. So this is a really profound question. It has been explored a lot by classicists, but I think in Robert Garland's book,

What to Expect When You're Dead, which we'll be covering in September, he really goes deep into it. He looks at not just ancient Egyptians, but also Hindus, Greeks, Mesopotamians, and the remarkable similarities between these different cultures. Building on that idea of what did ancient cultures think and the practices that they held

held around death. We have another really interesting one that we're going to be looking at this year. It's called Dead in Benares, an Ethnography of Funeral Traveling. And this is written by a sociologist. And so it's kind of really looking at modern day ethnography of funeral practices. When we talk about intersections of science and death, that can get pretty clinical. But in this case, while the author was working on this book, his father died. And so it becomes kind of a personal story that adds a little bit of that human element that is maybe

not as present in the other stories that we're discussing. Yeah, it's quite remarkable how that happens sometimes. The topic you're working on just becomes very personal. When he talks about Benares, Benares is a city in India, ancient name for it, or the historic name is Varanasi. And it's famous for being the place

that if you go as a Hindu religiously to die and then you're cremated there in the Ganges or the Ganga, that you can free yourself from the cycle of reincarnation. So a lot of people go there just to die. Very often when we think about death, it's something hidden away. It happens, but it's hidden away in people's homes or funeral homes or hospitals. This is a city in which it's out in the open. It's part of the atmosphere of the city. And I think that's what makes it

such a compelling story is that there's very few places in the world that can say that. Amazing. Well, I'm really looking forward to hearing all of these interviews with these authors. Thank you so much for helping us kick it off. And yeah, come back at the end of next month for the first episode in the book series.

And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write us at sciencepodcast at AAAS.org. To find us on podcast apps, search for Science Magazine or listen on our website, science.org slash podcast. This show is edited by Sarah Crespi and me, Kevin McLean, and we had production help from Podigy. Our music is by Jeffrey Cook and Nguyen Coi Nguyen. On behalf of Science and its publisher, AAAS, thanks for joining us.