Instant Genius - Spider season, with Prof Adam Hart

Episode Date: September 18, 2022

It’s that time of year again when we start to notice spiders coming into our homes. But what is the cause of this so-called ‘spider season’ and can any UK spiders actually cause us harm? Entomologist Prof Adam Hart from the University of Gloucester gives us the lowdown. Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Now, have you started to notice a few more spiders coming into your home? Me too. Now, the papers like to call this time of year spider season, as you all start seeing the eight-legged creatures stomping across our carpets and falling into our baths and whatnot.

But to find out more about the facts behind spider season, I got in touch with entomologist Professor Adam Hart. Here, he tells me all about British spiders and reveals whether we really are seeing more spiders in the UK. So spider season is upon us and we're starting to notice more spiders coming into our houses. But how many species of spider are there in the UK? Well, in the UK, we've got about 650 different types of spiders.

So a reasonable number, actually. But when you compare that number to, say, the 7,000 different species of fly that we have, for instance. It doesn't seem quite so grand. But yeah, there's a, there's a reasonable number of different types of spider that we've got here. Now, I mentioned that we've all been seeing more spiders coming into our houses. Now, are there actually more spiders come autumn time, or does it just seem that way? Yeah, no, what we're not seeing is more spiders. Those spiders have been around. They've been growing over the summer. They've been taking advantage of all the prey out there and doing well.

But come this time of year, what we're seeing, particularly in our homes, those larger spiders are male spiders that are on the move and they're looking for females. And they've been out and about, and if you work out in the garden or you have a garage, for instance, and you suddenly move a load of wood is a classic way to find them or start rooting around on a window sill. You'll see that they're out there. But what we're seeing now is that they move around a lot more. And we're just habitat, really. We're just part of their general sort of the countryside for them. In they move on the search for females. And of course, We tend to be inside sitting down on our sofas in the early evening when they're active.

And bingo, we tend to see them a lot more. That's all. And also, of course, the ones we're seeing those bigger house spiders, which are the ones that generally cause most of the drama. They're quite large, right? They're quite hard to miss sometimes. Whereas I had a shower early this morning. And in the corner of my bathroom, even though we check quite frequently, there's a falsed spider. So a sort of cellar spider, those sort of teardrop body shape, very long, thin legs that hang around in the corners of

rooms and it's probably been there a week or two and we've not noticed, you know, so they're very noticeable this time of year as well. But where do they suddenly all go? Because come winter, it's almost like they're not there anymore. Are they just not active in the winter? Yeah, that's right. I mean, like I say to people who are scared of spiders or who really dislike what's become known as spider season. It doesn't last forever. You're not sitting down eating your Christmas dinner and you suddenly see a big spider walking across the carpet. In fact, it tends to die down really by the end of this month. And yeah, they're there. They're there. They've done their business. They've lived their lives. So very often they'll die. Sometimes they'll overwinter. But yeah, they go into a sort of a much more, almost a dormant phase, a lot of these animals over the winter, the same as we see with a lot of invertebrates. So they're not particularly active. And in many cases, it'll be the females that sort of are resident in those little places in behind the freezers in our garage and so on. Just thinking of my big resident female that's out there at the moment. And they'll live for many years, whereas the males tend to,

live fast, die young, we see them scuttling around, and then you're right, we don't tend to see them again until the next spider season comes around, or if we spend some time out in the garden, we'll see them. And do other countries experience this spider season too, or is it just unique to the UK? Yeah, they do. We see at certain times of the year similar sorts of things happening where spiders seem to be more active, where you get a lot of males walking around. You can tell their males, by the way, particularly with the big house spiders. I know it's not everyone's a cup of tea to get up close to them. But if you get up close enough to see, what you'll see is they generally have quite small bodies, quite long, thin, kind of gangly legs, which is one of the things that tends to

put people off them, including me a little bit, to be honest. But if you look at the front, it almost looks in some cases like they've got 10 pairs of legs, I mean five pairs of legs or 10 legs rather than eight, because pointing out the front, they've got these structures called pedipalps. And in the males, well, they say they look a bit like boxing gloves. It depends on the species. In these house spiders, they can look more like sort of legs, but they'll have slightly swollen tips. And that's the organ that they use to mate with, actually. They transfer their sperm through that organ. And that's how you can tell they're a male.

They've got these really developed petty pups at the front and small bodies. The females, if you come across a big female house spider, they're generally like lay up. They're not massively active. They'll find a nice spot to be. They'll make those lovely kind of, well, depending on your perspective, those lovely sort of sheet webs. And they'll sit there basically getting fat. And the reason why is that they have to produce lots of eggs. So their strategy is a little bit different.

They want to be nice and big and chunky, big ovaries inside, lots of mass, if you like to to be able to transfer that into young, whereas the males are kind of mating machines, really, scuttling around looking for opportunities. And they're often much smaller. And in fact, some spider species, there's a spider that I see quite frequently in South Africa, where we take a field trip, for instance, called Nafila. It's a big orb spider. And the female's huge, like, you know, palm-sized spider that bigger sometimes,

that make these spectacular webs between trees and bushes. And if you're very careful and you look very closely with a pair of binoculars, you might just spot the male. It's just this tiny little thing, scuttling around in the web. And again, it's a live-fast, die-young strategy for the male. He needs to get there, get his sperm transferred, ideally avoid being lunch, although in some cases that's actually part of their strategy. They offer themselves to the female, and as she's consuming them,

they transfer the sperm in some species, which is quite a dramatic way of mating, and they move on. And, you know, I mean, really, I guess the overarching thing with spiders is that whether we like them or load them, and some people are really, don't like them. They do have really fascinating lives. They're incredible, incredible creatures, and they've got all kinds of interesting stories going on. I mentioned house spiders, some of the biggest ones were likely to see. But what other species are likely to come into our homes? Yeah, so there's a handful of spiders that we call the house spiders, and they all look pretty

similar. They're in two different genera, and they're quite hard to identify, actually, between species. In some cases, I think you have to be digging around and getting the genitals out and stuff under a microscope. So some of them can be quite tricky to ID, but there's a sort of handful of those they're the ones that they're the big leggy males you see wandering around the carpet that cause everyone to have a bit of a jump the classic autumn kind of house spider as well as those the spider the spider where most probably commonly see is what's called the cellar spider which are the ones I mentioned earlier the sort of tear drop shape very long leggy spiders that hang around in the corner there are a few other species you see if on a warm day and just outside of my back door I get

zebra spiders which are lovely little very engaging very small little spiders that run around. When you look at them close to the little zebra stripes, sometimes they find their way into houses. Sometimes the big garden spiders as well, the ones that we see in autumn making those fantastic webs, and they sit in the middle of them and they've got that little cross on them, the classic garden spider,

they sometimes find their way into houses as well. But generally speaking, the spiders that sort of like to make our habitat theirs, if you like, belong to those sort of two genera that are quite difficult to distinguish. And they're the ones we normally call the house spiders. How big can a house spider get? The answer to that is surprisingly big. The biggest one that we get in this country is something called Eredragona. It's called the Giant House Spider.

And they're the ones that I think are sometimes called Cardinal spiders, because they so frightened Cardinal, I think it was Cardinal Walsley in Westminster Abbey or somewhere. Very, very big animal. The largest one is 120 millimeters. That was the biggest, which is about the diameter of a compact disc, apparently. So quite big. That will be fully stretched out, obviously, and the females, again, are generally larger than the males. They're more heavy set as well. They've got that bigger kind of abdomen to produce sex. So these things can be really quite impressive. Most of the spiners that we see are much

smaller than that, although, of course, they can look bigger. I see this with wasps as well. One of the curious things about wasps when you see them flying around and when you see them dead on your windowsill, a lot of people say, oh, they look much smaller. Things tend to look a lot bigger when you feel more threatened by them, or if they've suddenly caught you on unawares, where you see it against the white. I'm looking across this room, I'm in there. There's some white skirting board, which actually is a 120-mills skirting board, I think, looking at it, if I saw a big spider on that, it's against whites, there's nothing around it. That is going to look much bigger to my brain than if I was out in the undergrowth and saw it wandering around. That's another

interesting thing about spiders, and I fall into this trap a little bit. If I'm out in the countryside or I'm out in habitat or I'm out in the field. Spiders are spiders and I don't really take much notice of them and I think they're cool and I'll brush them off a rock and get on with it. But in the house it's slightly different and I'm an entomologist and I've studied spiders and I like them but I'll still jump if I see one walking across. There's still that like oh and it's yeah, it's a curious thing. I think it's partly because there's no background, partly because they are quite big

and it's partly because they're in our house and we're not, we're not expecting them. It's that surprise I think that can something. times do for them. Yes, when you can't fit a glass over them to catch them, and that's when you know they're big when their legs are still standing up. Yeah. I was once told by someone I was working in Panama that there are only three types of spider, and I said, oh, how so? And he said, there's, and this guy really hated spiders. And he said, there's boot heel spiders, there's newspaper spiders, and there's shotgun spiders. And that was his three size categories. But I think you're right. Yeah, if you can't get a pint glass over the top of it, you know, you're dealing with a, with a big one. But yeah,

Fortunately, those very large ones are not as common as the much smaller ones. I've had a few fairly impressive-looking males, actually, so far in the house over the last couple of weeks that have caused a bit of drama. We managed to deal with those okay. But yeah, they were quite large. So I think we'll have to see how the season progresses. It's always a strange thing when you deal with things like house spiders and wasps because I'll talk about, oh, it's been a good year for wasps. And what I mean, or a good year for spiders. And what I mean is, yeah, there's loads of them about and they're doing really well.

you know, that's great, good news story for the environment. But of course, if you don't like those animals, then it's been a bad year. It all depends on perspective. So we said about how big some of these spiders can get, and we know that a lot of people aren't too keen on spiders. But are there actually any dangerous spiders in the UK? Well, look, the UK has a remarkably harmless sort of fauna generally. Flora not so much.

There's a few plants out of that they can do us a bit of harm and the old fungi. In terms of spiders, there are about a dozen species that have been known to to give us a bite of those. Obviously, if you are bitten by a spider, it's not a very pleasant experience. Most of them are described as no worse than a bee sting, but haven't been stung by bees on a number of occasions. I can tell you that's not a very pleasant experience either. The reality is that we have very few species in this country,

which can cause any problems at all. We're starting to understand that the false widow spider can, in very unusual circumstances, you know, very rare occasions have a bite that can cause some medical concern for some people. However, we've had them in this country for well over 100 years, or close to 100 years, and we haven't really had a major problem with them. We are seeing them more commonly now, and people are occasionally getting bitten, but it's still a pretty unusual thing. The big house spiders can certainly give you a bite.

I remember my dad being bitten by one once, which he wasn't very happy about, but it really didn't cause very much harm. It's rare. And to be honest with you, most of these spiders, they're not looking to us as prey. So if you get, well, no spiders are. So if you get bitten, it's a defensive bite. And most animals that bite defensively when they're small, they're not looking for trouble because we're going to kill them.

So that defensive bite is generally if they're being crushed or handled in some way. So, you know, I know a lot of people like to pick up spiders and it's kind of a party trick for people because they know a lot of people don't like them. You know, animals don't generally like being handled. So I normally say to people, you know, that's great, you know, fabulous that you're picking these animals up and you're not harmful by them. and if that helps people realize that they're okay, then that's good. But at the same time, if you've got a spider in your hand, you've got a much bigger chance of being bitten than if you don't. So personally, I tend to steer clear over those things.

But generally defensive bites what we're dealing with, and they're very, very uncommon. You know, my dad got bitten once. That's the only person that I actually know who's ever been bitten by a spider. It's the sort of thing you tend to hear about. I think there's a feeling that it's more common than it is because every so often you'll see on the front page of the news, some terrible story about somebody that's been bitten by a spider and there's usually a

picture of a massively swollen leg somehow related to the spider bite. It's usually very unclear how. Actually, the swelling is caused by infection. So it's really punctual wound. It's often, yeah, there's a lot of, so we say, mythology, but also perhaps a lot of some sketchy reporting. So if you're living in the UK, we have plenty of things to worry about. And there's always something else we can add to the list. But being bitten by a spider should be very, very low down your list of concerns. It's very, very unusual than it happens. And if it does, it's exceptionally unusual that anything untoward will occur. So yeah, we don't need to be living in fear of our spider fauna. So what's the best thing to do with a massive spider in your house? Should we just leave them

be or will they be all right if we put them outside? Well, okay, so leaving them be is a lovely thing in principle, but unless you're enjoying sharing your home with very large house spiders, and you don't mind suddenly turning a corner and then being there or, you know, turning over in bed and finding one or whatever. You know, if that's the case, then yeah, have at it. But I think most people feel more comfortable if the spider is removed. Now, obviously, the easiest way to remove a spider, and, you know, let's speak plainly here, is to kill it. You know, that's the problem solved, or then you then have a problem getting rid of the body, which a lot of people that though like spiders have almost as much of a problem with us the living spider, which is worth

bearing in mind. But we don't really want to be doing that. There's, there's no need. They're harmless. They perform a very important ecological function if we want to look at things in that way. They're fantastic predecessors and stuff. And really, there's a very high chance that the spider that you're looking at is just a male house spider on the look for a female spider. So if you can give them a helping hand outside, you know, they're not hell bent on coming into your house and, you know, taking out residence under your bed or anything. They're just, they're out roaming. So if you can get them into a glass with a card underneath and hoi them outside, that's, that's an admirable thing. Well done and do that. There are devices that you can buy

that will collect spiders for you, including a sort of, it kind of looks a bit like an upside down dustpan and brush on a long handle. You sort of plonk over. There are quite a few products for doing this, that if you don't fancy doing that, probably worth investing in, you can be at arm's length and you can take them out. I say this as someone, I will put spider in a glass and stick a card under it and put it outside, but it's a strange thing. I'm quite happy with long-legged insects and all sorts of stuff, but there is something about spiders that seems to release something in me that's a little bit different. You know, I've learned to overcome that and sort of do the right thing by them, but I do completely appreciate, you know, some people really don't like

them and they find them very freaky and they can't overcome that. In that case, getting them in a glass and having them scuttling around in there on top of a piece of paper that you can possibly even feel the sort of vibrations coming through. That is not going to be what people want. What you're going to end up within that situation is a loose spider and a broken glass, which is then two problems to deal with. So yeah, if you're in that situation, but you know, you want to do the right thing by them and that's what we should be doing, then look into perhaps some of these sort of spider products that you can get. Just have it, have, have a, available so you know where it is, right? And if you do find a spider, get it in. If there's someone

else in the house, there's another bit of advice I have. I've been trying to tell my children, there's a spider in the house and it's like, where is it? I don't know. I came down to tell you. And it's like, there's two of you. One of you keep an eye on the spider. One of you come come and get help. Because what will happen most of the time is there'll be a bit of a commotion. The spiders can see, they've got good vision and so on and senses. They'll, they'll scuttle away and try and try and hide. And in houses, that means scuttling under something or behind something. and nine times out of ten, that'll be something you can't move or whatever, and you've lost the spider,

and then you've got that sense that you're sharing a house with this big spider. So, you know, come up with a bit of a spider protocol this time of the year, if this is a problem for you, what are you going to do if you find one? If there's someone else in the house, have your spider removal tool, and you can turn a drama into a fairly short-lived, a short-lived thing and get your spider outside. That's my advice. But easier said than done.

I know, you know, sometimes it's difficult. Well, I suppose the classic thing is you get the spider in the bus, Now, can they climb up the plug hole? No. And when you look at the interventions of the plug hole, I mean, I'm involved in some home improvements and an extension at the moment, so I'm developing a much greater understanding

of how plumbing and things work than I had before. And when you think about it, in order to get up the drain, they'd have to be in the drainage system, which is full of water and all sorts of other stuff, coming down constantly. It's not good place for spiders to be. And they would find it quite hard to climb up. They end up in the bath because they're wandering

around and they fall into the bath and our baths are very smooth now spiders are incredibly good at climbing up things but then they rely on there being tiny imperfections on the surface that they can get little hooks on their legs into and on the tips of their feet and climb up now many of our baths don't have those so they struggle to climb up so that's why they've ended up in the bath they basically got in there and they can't get out some people recommend i believe you can even buy a little spider ladder um you don't need that just a piece of string or something like dangling down that gives them a grip. I saw a spider here a couple of weeks ago that was climbing up a piece of string that was hanging down from something. And it was sort of half on the string and half on the wall. And it was

using a string as a bit of purse. It was quite interesting to watch, actually. So you just need something that can get them out. But again, some people prefer that when they come in the morning, they find one in the bath and they can remove it because then they know that there was a spider in there, but it's now outside rather than not knowing whether. So there's a very strange, not very strange, there's just a kind of interesting psychology involved with a lot of the sort of phabias and things around spiders. So it all depends on what you want to do. But yeah, you can certainly leave something in your bath to help them out if that's what you want. So if you're scared of spiders, you do want to stop them coming in, do any of those folk myths work, you know, conquers,

essential oils or not? Yeah, and there's all kinds of ones. I went to Istanbul a while ago and noticed that there was an ostrich egg hanging up in, it was in, I think I was in the Big Mostar. I can't remember its name now. And yeah, there was an ostrich egg there. And my de facto brother-in-law at the time was a tour guide. So I asked him about it, and apparently that was there to keep spiders out and stuff. So it seems that there's lots of these around. The Royal Society of Chemistry in conjunction with a load of school children a few years ago did effectively a citizen science experiment where they got schools to test. They got them to catch spiders and put them in very elegant system, really, put them in a choice chamber with conkers and without conkers and just find out, you know,

do the spiders avoid the areas with conkers? And the absolute and completely damning evidence was that if anything, I believe there was a slight preference for conchers. I can't remember now, but they certainly don't show an aversion to them. So, yeah, I think what happens is it's interesting. This time of the year, we get spiders around, and then come about October, we start getting the conkers coming down. And at that point, we don't generally see the spiders around so often. There's a sort of a die-off, if you like, of spider sightings,

because the males have done what they need to do. The females are getting ready for the winter, and they're not being active anymore. And we saw that when we did our citizen science study of, house spiders. We see this very steep decay curve dropping off towards the end of September. And I think it's just one of those coincident things that people notice there are spiders around and then they notice there are conkers around. So I think that's what's happening at this time. Yeah, I think we're seeing this decay of house spiders around to the late September time early October. And then we're seeing the conquers developing and being around. And we tend to,

we like seeing patterns, right? We like seeing one thing causing another. And I think that's possibly what's happened with that. So yeah, there's lots of different types of myths around or folk lore around about keeping them out. The ones that have been tested don't seem to have any effect. But if you've got some ancient family recipe that you like to spray around this time of year and it works for you, then great. And also, you might be onto something, right? There may well be something out there that causes them to be repelled.

But so far, unfortunately, we don't seem to have found anything too reliable. We'll keep trying. I know, touched on it early. You said that from an ecological perspective, spiders are really important. They're big predators. They eat insects and things like that. But in general, are spiders in decline, or are they doing pretty well? Well, this is one of those questions that's very difficult to answer.

And one of the reasons why is that we're not doing a huge amount of surveying of so many different types of invertebrates. And spiders generally are quite low down the list. There's not huge numbers of people studying them. So it's difficult to say in many cases. Spiders, they are predators, and they rely therefore on prey abundance. And many of their prey will be insects. So if we are seeing, as we are in some areas, declines in certain types of insects,

if those insects are the prey of spiders, then it makes sense certainly ecologically for them to be some knock on effects. So the simple answer to the question is, we don't really have the data to be able to say in many cases, but the more complex answer is there's no reason to assume that they wouldn't necessarily be suffering slightly if we see their prey organisms suffering. But some of these interactions can be very complex,

and ecology is really straightforward in terms. of only one thing going on. On top of that, you've got differences in seasonality, for example, you'll have the differences in weather, all sorts of other things that can cause annual changes. So as with all of these things, when we're trying to see long-term patterns, what we need is long-term data. And there will be a few studies of long-term spider abundance around the world. I know there's one going on in Australia at the moment that shows the importance of urban environments for spiders, for instance. So we are developing more of a picture. But at the moment, It's not sort of possible to give a simple answer to are they doing well or are they not.

But yeah, gut feeling has to be that if their prey are not doing so well, then they're likely struggling too. And of course, on top of that, we are changing the habitat as we go. We like to remove hedges that spiders like to be in. We make our houses much less friendly for different species. We clear out our outhouses. We change the structure of our gardens, for example, with different types of construct. construction techniques and different types of flooring, you know, fake grass and sort of lots of concrete work and things which doesn't necessarily encourage a diversity of all types of

different organisms and spiders would be included in that too. So yeah, overall, we need more data, but my gut feeling is that they will be struggling a little bit as well. Thank you for listening to this episode of Instant Genius. That was Professor Adam Hart, an entomologist and science communicator from the University of Gloucester. The latest issue of BBC Science Focus magazine is out now. Pick up a copy in store or visit sciencefocus.com.

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