13. The Fastest Fly

This BBC podcast is supported by ads outside the UK.

Start your journey toward the perfect engagement ring with Yadav, family owned and operated since 1983.

We'll pair you with a dedicated expert for a personalized one-on-one experience.

You'll explore our curated selection of diamonds and gemstones while learning key characteristics to help you make a confident, informed decision.

Choose from our signature styles or opt for a fully custom design crafted around you.

Visit yadavjewelry.com and book your appointment today at our new Union Square showroom and mention podcast for an exclusive discount.

At the BBC, we go further so you see clearer.

With a subscription to bbc.com, you get unlimited articles and videos, hundreds of ad-free podcasts, and the BBC News Channel streaming live 24-7.

From less than a dollar a week for your first year, read, watch, and listen to trusted, independent journalism and storytelling.

It all starts with a subscription to bbc.com.

Find out more at bbc.com slash unlimited.

BBC Sounds, music, radio, podcasts.

I'm Hannah Fry.

And I'm Dara O'Brien.

And this is Curious Cases.

The show where we take your quirkiest questions, your crunchiest conundrums, and then we solve them.

With the power of science.

I mean, do we always solve them?

I mean, the hit rate's pretty low.

But it is with science.

It is with science.

Welcome to another episode of Curious Cases.

Today we're going to be investigating insects and specifically flies.

We're going to fill a half-hour show.

Oh yeah flies, flies, there's loads of stuff about flies.

Did you know there are more species of fly in the UK than there are mammals on the planet?

I didn't know that.

Yeah.

And also, I doubt it.

More than 7,000 types of fly.

In the UK?

Yeah, in the UK.

That does sound like a made-up made-up fact.

It does sound like a made-up fact.

Absolutely.

Yeah, yeah.

But another one for you.

There are several types of fly, and this seems massively counterintuitive that don't have wings.

Is there?

Yes.

Like in the joke.

What do you call a fly without wings?

No fly.

No, no.

A walk is the actual joke, right?

The New Zealand bat fly has no wings.

Right.

So hang on.

It feels like a real prerequisite to being in the fly category.

It almost seems like a sine qua non, as they say, without which you are not a fly.

It seems ridiculous.

One of the things that guys mentioned is their speed.

And that's exactly what this week's lister wants us to investigate.

James Polk wrote to say.

My seven-year-old son has a book about insects, in which we were amazed to read that a species of horsefly has been clocked at 90 miles per hour.

My intuition, not backed by any real understanding of the subject, tells me this is nonsense.

I don't want my son to go through life believing this unless it is true.

Can you help with finding out what the fastest flying insect really is?

And can anything be learned from insect flight that could be applied to man-made flying machines 90 miles an hour i mean that does sound it's fairly quick isn't it it's fairly quick if you were going down the motorway in the same direction as a fly you would never swat it on your windscreen no i mean you also wouldn't expect to be holding to the national speed limit and have a fly just slowly overtaking you which is essentially what this thing is implying now i don't know

surely on the slow lane undertaken by a horseby god if they're on the slow lane that'd be horrendous like they but if they're just coming up beside you and you you clock eyes with the fly fly and they give you a wink and then they just keep going, that'd be a show of strength, wouldn't it?

You know what?

I take it all back.

I think we can fill half an hour with working out whether this is true.

If anyone helped us get to the Bobblis, it's the two people with us in the studio.

Professor Graeme Taylor, studies the dynamics and control of animal flight.

And the entomologist, Dr.

Erica McAllister, better known as the fly lady,

who is

surely going to be able to help us.

Erica, many of us hate flies.

But not you.

No.

And you're on a mission to convince us we're wrong.

You are wrong.

Sorry, that's a bad start.

No, it's fine.

There's a lot of flies.

There are a lot of flies.

There's a lot of 7,000, apparently.

In the UK.

165,000 described globally.

We think that's a massive underestimate.

And they get everywhere.

Their little tarsa are absolutely involved with everything.

And the flies are part of the dark taxa.

So they're the ones, oddly, the least describes because there's a lot of tiny little black flies.

So how many of the 7,000 different species of fly are just tiny little black flies?

In the UK, there's quite a lot.

There's entire families of them.

You're like, oh.

You've handed me a jar of tiny little black flies in liquid.

Yeah.

These tiny little black flies are part of the biting midges, which everyone hates.

But those ones are the pollinators of chocolate.

If it wasn't with these.

Yeah.

Yeah, and yet.

So these are amazing because these are some of the fastest wing beats.

So there are a thousand wing beats per second.

Well, this may become critical because we want to get into it speed, Russi.

Can I, however, ask you about flies that have no wings?

There are loads.

Really?

There are flies that actually start off with no wings, or there's flies that once they've copulated, rip their wings off, which is a brilliant thing.

In fact, my favourite fly...

No, no, afterwards, because a lot of flies give birth to live young.

Right.

Which is quite an odd thing anyway.

And there's this one fly that it's on my hit list of things to see on the planet.

Because once she's copulated, she sticks her head in the side of a bat because she's feeding off the bat and she rips her legs off and wings off and then basically pulls her

how do i say this pulls her her bum completely over her body so you're just looking at her anal spiracles which just looks like a little smiley face and i just think the idea of seeing a little bat with little smiley faces on brilliant sounds like a friday night in essex doesn't it

it's only so it's post

no some are born without them

what did they do how did they get from a to be walk

It's that joke.

I know, but I mean, what do you want me to say?

Some of them have...

How are they flying?

They are because of how we can link them to their siblings.

Our average house fly...

Is there more than one type of episode?

Over 300 types of flyers.

I knew I was going to say, you know, I thought I'd try 50 maybe.

There's the fat fly, the slightly blue fly, and that's about it.

Yeah.

Honestly, I didn't, when I had to do my PhD, some of my colleagues were like, I don't know why you bother.

There's just flappy flies, annoying flies.

Yeah, but the ones that, you know, flip backwards off a table when you're trying to hit them.

What?

When you're trying to kill them, Erica.

When you're trying to...

So if I came into your house and tried to kill your puppies, you'd be really upset.

I will be furious.

I'd be furious.

But it's an amazing thing.

I don't doubt it's an amazing thing.

And then there's...

Have you heard yourself?

I'm just saying, we don't give them enough credit.

Like, we're all ready to blame them for the zzz bit.

But that's a fantastic thing.

Do you know they flirt by that?

I did not they sing to each other to me, they don't you don't know what they're doing with you, yeah, and maybe desperately because.

Um, um, oh, what?

Because I'm bald,

you were like dancing around, you could you were looking at the top of my head.

Your head is a really good place for them to leck off,

right?

Lecking, you know, like dear leck, and they have they go to certain places.

Um, sometimes you're lecking, but yeah, bald head, they all will congregate above his head

because they chill out, no, because they're everyone that's reflected, so so the flies can, they all recognise an area they can go to.

So if you were rowing across a lake, you would have like this massive, like mating plume going up from your head.

And this did start with horse flies.

That was the point of this.

It was.

I'm just enjoying this too much, though.

I know, I know.

I don't even want to tell her about the electrified tennis record.

No!

No!

No!

A horsefly.

Yeah.

There is a claim.

Yeah.

I feel you've heard it before.

Yeah.

Yeah.

That they can fly 90 miles an hour.

Yeah.

We have been interested in insect flight for a long time and we should probably go back to the beginning with a dude who did the best claim, which is Charles Townsend.

He's a character and he fell out with pretty much everyone, which is great.

So he was doing with the bot fly, which is actually the cute little fluffy one.

Yeah, now the record showed that you've opened a carbohydrate box of massive flies.

I also can't describe any of these as cute.

I've got to be honest.

But they're hefty.

These are big bees.

What do you mean?

Look at that.

So, everyone loves bees.

That looks just like a bees.

It does look like a beef.

I don't know, but it's better.

It's a deer bot fly, so she squirts her larvae up the nostrils of reindeer and things like that.

How fast was that supposed to be?

Apparently, that broke the sound barrier.

That was the claim we made.

Can I read it out?

Because it is just proper bonkers.

Okay, go on.

What he said was that regarding this species, the idea of a fly overtaking a bullet is a painful mental pill to swallow, as a friend has quaintly written me.

Yet these flies can probably do that of an old-fashioned musket ball.

They could probably have kept up the shells of the German Big Bertha in Paris during the World War.

I mean, this was written just after World War I.

The males are faster than the females because they must overtake the latter for quotian, which I think is rather sweet.

I think I should use that.

It's a mating habit.

Run as fast as you can, and then get in front of them and trap them.

So at 7,000 foot above the Sierra Madre in Mexico, I've seen gravid females pass while in search of hosts at a velocity of well over 300 yards per second.

So it's 274 meters per second.

Yes.

Okay, but that's...

Otherwise known as fast.

Okay, but that's just the females, remember?

On the other hand, at 12,000 foot summits of New Mexico, I have seen pass at me the incredible velocity with what was quite certainly the males.

So I could barely distinguish that something had passed, only the brownish blur in the air.

As closely as I can estimate, their speed must have approximately 400 yards per second.

400 yards.

That's like 365 meters per second.

Which, how many seconds are there in a minute?

One second?

Yes.

I mean an hour?

Yeah.

Right.

Let me 65.

So that is about...

Oh,

look at that.

1.3 million meters an hour.

Which would be 900 miles per hour.

Yeah.

I mean, this guy is...

And he's just picking this number off the top of his head.

No, he's a serious scientist.

Serious.

So wait, that's the deer fly.

Yeah, no, that's the butterfly.

Yeah.

So it's not even getting onto the horse flies.

We're not taking that number seriously.

No.

We're not.

We're taking it as an example of...

This is a difficult thing to do.

And then people have taken a punt at it.

Yeah.

So the 90 miles per hour for the horse fly.

Right.

So we're going to a much smaller fly now.

Which one's horse flies?

I'm giving you four horse flies.

These are two of the biggest.

That's the UK's largest.

That one.

Yeah.

I don't think I've ever seen one of them.

You would know they can break into your car.

They can't.

They can't.

But everyone goes, oh my god.

Okay, how can we describe this?

I mean, the wings are very beautiful.

The rest of it less so.

It's got stripes on the back, but not quite yellow and black.

It's sort of much more browny.

I mean, it sort of just looks like a massive fly had a baby with a bee.

Hmm.

But that's.

Would you accept that?

Well, there's also what I've given you is a male and a female.

Which one's male, which one's female?

Well, the male I think looks quite rude.

Oh, right.

Yes.

Okay.

I would say it's much more phallic.

Yes, I think that that's fair.

So she's looking for large vertebrates, she's looking for easily, slow-moving things.

So she's looking at a difference between like shade perception and things like that.

Whereas he's trying to find her.

So he needs more eyes.

Not to bring us crashing back to the issue question.

However, the 90 miles per hour claim, who made that claim?

Jerry Butler.

And what was, was there any scientific method to that?

He shot out a bullet.

Yeah.

The horsefly caught it and dropped down with it.

So they timed it from when it came out of the gun and when it dropped.

And so they were using that distance to work out the timing.

I'm sorry, what?

The horsefly caught the bullet.

Is that what we're saying?

Yeah.

In his teeth?

He's got no teeth?

I'm trying to work at the logic of this.

There's a bullet firing a pellet.

Yeah.

Why?

No, there's a gun firing it a pellet.

A gun firing a pellet.

Sorry, apologies.

Why would the bullet fly a pellet?

That's ridiculous.

I mean, it's not the most ridiculous thing we've heard already this morning, but why would the horsefly care?

Because apparently, it thought it was a female.

Oh, so you disguise a pellet as...

No, no disguise, apparently.

This is a really upsetting thing I've just learnt today, is that the male perception is not really that good.

good

so anything flying past

at a reasonable speed let's go for it

i mean that's really disappointing and that's why they break into your car yes oh are these things copulating in mid-air is that how some do some adoption does happen a lot though i've i've noticed it in the house recently above your head i just i walked into a couple of rooms and and there's been dragonflies and you've kind of gone you've got dragonflies in your house oh the dragonflies come to the house every software exactly and let's say flying in close formation around the kitchen, and you're kind of going, oh, please, get a room, lads.

Actually, it does depend on what species, because some can happily fly along, the females dragging the males behind them.

It depends on the rotation of the genitalia.

Okay, we don't have to get into the specifics, though.

But with house flies, they're definitely.

Yeah, if you see two of them very closely together.

But they're on top.

So

they won't be doing it.

They will drop down generally.

Right, okay.

I think we've established some interesting history of fly science.

but, and I'm not saying that you've torn down this statistic altogether, but I think we need a little bit more thinking through where this 90 mile now comes from and whether we can make it a bit more rigorous.

So, Graham, if I come to you, are cameras the only way that you can calculate this?

Well, there is another way we could try, which is a sort of reality check on the number, and that's to make use of one of these things called scaling.

So,

When you look at the way that animals, they're capable of moving and so on, you find there's a really strong effect of scale.

So there was a very, very famous quote from another one of these old scientists called JBS Halding back in the 1920s, who talked about being able to drop a mouse down a thousand yard mine shaft and that on arriving at the bottom, provided the ground was reasonably soft, a rat was killed, a man was broken and a horse splashes.

So wait, this is like the size of their bodies compared to how much it can act as their own parachute perhaps.

Well, it's partly to do with how quickly you would fall and to be honest, I don't know whether he actually did the experiment.

I'd rather hope not.

No, it's really to do with your ability to resist the impact when you land.

So if you think the way that your momentum is going up, it's scaling with your mass.

So that's your length cubed.

You're resisting that with something that depends on your cross-sectional area when you hit the ground.

That goes up as length squared.

So the end result of that is you've got much less area to be able to deal with the impact force that you then have to sustain.

So there are experiments that were done in the field with actually fairly standard cameras recording at 50 frames a second and monitoring how quickly a horse fly flew across the field of view.

And the end result of that was it was 13 miles an hour, which is nowhere near the 90 that we're talking about.

Are you sure those horse flies were really motivated though?

We're not sure they were really motivated.

There were certainly no air pellets being fired from rifles and as far as we know there weren't any females being chased either.

But if we want to kind of understand scaling and how that applies to flight we need something a little bit more sophisticated because it's all going to come down to how much thrust you can produce relative to the amount of drag.

So as you speed up, you're going to increase the amount of drag that you experience, and at some point you hit your terminal velocity.

And so, there's a very convenient way that we can look at this, and that's something called a dimensionless number.

And there's a dimensionless number called the Strahl number, which is something I worked on about 20 years ago.

And what we found there was that when you look at animals in cruising flight, all of the animals that we looked at, and in fact, swimming animals too, cruise at the same Strahl number.

So, I sort of need to explain that.

Regardless of what animal?

Well, within a kind of narrow range of 0.2 to 0.4, from a bumblebee up to a dolphin or a shark, you find that the way in which the oscillating surface that it's using for propulsion moves, that looks pretty similar.

Like there's a secret underlying law almost that appears again and again amongst lots of different species.

Yeah, well, it's not secret now because we published it 20 years ago, put that aside.

Yes, there's this underlying law which...

There's a mystery to it.

So what you need to think is that to push yourself through a fluid, whether that's air or water, the amount of energy that you're putting in, that's going to depend upon how quickly you're beating your wings.

Whereas the kind of drag that you're experiencing in flight depends upon your forward speed of motion.

And so the ratio of how much movement you get of the wing from the top to the bottom of the stroke relative to how far you've moved forward in that stroke, that's actually pretty consistent.

And so If you use that as a way of analysing the flight, we can at least come up with a simple reality check of whether this is plausible or not.

Because if you imagine if you were just moving your wing up and down very slowly, you're not going to overcome the drag that it produces.

Won't be enough thrust.

We need to reach at least some critical level of that Strahl number to have any credibility at all.

So unless we come up with a number that's a bit above 0.1, maybe 0.15, then this isn't a credible.

Is this a calculation we can just do now?

Yeah, we could try it now.

Yeah.

The Strahl number is the, if you take the wing beat frequency, and that's around 150 times a second.

And then we're going to need to multiply that by the distance that the wing travels from the top to the bottom of the stroke.

Okay, so if we're really generous on this, it might manage twice its wing length if it goes from vertical to vertical, top to bottom.

So we kind of need the wing length of the fly.

Average 9.5 millimetres?

9.5 millimetres.

I think we can probably round up to keep the calculation simple.

So if we round that up then, we've got 0.01 meters.

times 2, because it can go up and down, times 150.

And I'm relieved to see that you're using a computer for simple arithmetic, Anna.

And if we then divide that through by this alleged speed, so 90 miles an hour, that's 40 meters per second, I think, isn't it?

Then we should come up with a number.

Hang on one second.

So 150 times 0.02 divided by 40.

I get 0.075.

That's what I got to.

And unless it's above 0.15, not possible.

I mean, there's a little bit of wiggle room around that, but if you're down much below about 0.15, we don't really see things producing net thrust.

So at that point, actually actually moving a wing up and down is probably not helping you to fly forward at all.

I'm taking things forward.

If we just proved that this insect can't fly at all,

it's a walker.

Yeah.

But wait, we know it does fly.

I mean, are we now reclassifying this insect entirely?

It can fly.

It can fly.

It definitely can fly.

Yes, we know it can fly.

I can see wings.

Yes.

So what you have to imagine is that as you start beating your wings, when you're flying slowly, you're going to generate an excess of thrust.

So you speed up.

But as you speed up, your drag increases too.

and eventually those two come to a sort of balance, and at that balance, equilibrium point, that's the speed that you reach.

So if we would have worked the calculation the other way and now say, well, what's the fastest we think it could do, that number we came up with was about half what it needed to be.

So I think the highest credible speed we could possibly get to is about half what Jerry Butler claimed.

45.

Potentially 45 miles an hour, but I really wouldn't be hopeful about the prospects of capturing that kind of speed.

And I think a more realistic kind of number, if we work on the basis that most things sit between about 0.2 and 0.4 for the Straule number, more realistic kind of number, I'm afraid, is getting down to about a quarter of what he measured.

So the max has gone from 90 to 22 and a half

miles per hour.

But it's still quite impressive.

No, no, no.

Absolutely.

I mean, you'd certainly be Olympic level.

Think of it on a treadmill.

I mean, that's above level 20 on a treadmill.

That's gone.

That's gone.

That's really going.

To keep the maths easier, if we say 10 metres per second is about reasonable for this horse fly, then yeah, that's your 100 metres in 10 seconds.

The desert locust is the one they've actually said is the fastest, isn't it?

But they've got a speed there of 20 miles per hour.

So is my horse fly still faster?

Please say.

Our generous upper limit is.

Okay.

Yeah, I'd go with the generous upper limit.

With a Wealthfront cash account, your uninvested cash earns 4% annual percentage yield from partner banks with free instant withdrawals, even on weekends and holidays.

4% APY is not a promotional rate, and there's no limit to what you can deposit and earn.

Wealthfront.

Money works better here.

Go to WealthRunt.com to start today.

Cash account offered by Wealthfront Brokers LLC member Fenra SIPC.

Wealthfront is not a bank.

The APY on cash deposits as of December 27, 2024 is representative, subject to change and requires no minimum.

Funds in the cash account are swept to partner banks where they earn the variable APY.

When never thought this would happen, actually happens, Serve Pro's got you.

If disaster threatens to put production weeks behind schedule, Serve Pro's got you.

When you need precise containment to stay in operation through the unexpected, ServePro's got you.

When the aftermath of floods, wildfires, hurricanes, and other forces that are out of your control have you feeling a loss of control, ServePro's got you.

Simply put, whenever or wherever you need help in a hurry, make sure your first call is to the number one name in cleanup and restoration.

Because only ServePro has the scale and expertise to get you back up to speed quicker than you ever thought possible.

So, if fire or water damage ever threatens your home or business, remember to call on the team that's faster to any size disaster at 1-800-SERVPRO or by visiting SurvePro.com.

ServePro, like it never even happened.

There are some experiments though where you can monitor flies flying, though, right?

I mean, I remember one particular experiment reading about it where they had a fruit fly in a sort of VR machine.

Yeah, so

to get, well, to be able to study these things,

usually it helps if things stay in roughly the same place.

And so, actually, a lot of experiments on flies are done by tethering them.

So that means sticking them to a stick.

Sometimes you're doing other things like recording from the neurons in their brain at the same time.

Give them a little hat.

Sometimes you're doing what we've done, which is to put them in a particle accelerator and fire x-rays at them rather than

plastic pellets.

And that allows you to look inside.

More and more starting to be on your side, okay?

They're horrible to fly.

Well, this is in the name of of science.

So if you want to start tethering an insect in one place, though, you do need to really give it the illusion that it's flying.

And because flies and other insects are such visually guided animals, then you can do that in part by surrounding them with moving visual stimuli.

So we've done that by putting a fly in the middle of a sphere and we kind of project images onto the back of that and it sees through that.

So it's as if it's surrounded by this massive 360-degree cinema.

Bring a fly to an eye mouse and then

make it watch, you know.

Other flies.

Like a Christopher Nolan movie about flies on the IMAX and then measure it and then see what it's doing.

Yeah, that's right.

So you can measure it.

You can do that with a horse by then.

Well, we could do.

We've just never tried.

I just want to go back to that point that you mentioned about thrust and about how sometimes the calculations seem a bit off because there's something known as the B paradox, right?

Yeah, so it's all based on this thing called the quasi-steady assumption.

Okay, and the idea of that is that if you were to freeze at any instant in time how the wing is moving and it had been moving like that forever, you can calculate the forces that it would have produced under some sort of simplifying assumptions.

So in other words, that's the way you would model an aeroplane wing.

And provided it's not doing anything too dramatic, that works pretty well.

But if you now have a bee which is beating its wings up and down a couple of hundred times a second, 100 times a second, then the aerodynamics, funny enough, change from that.

And so, what the calculation is really showing you is actually that the aerodynamics of a bumblebee's wings are not the same as those that we got on most aeroplanes.

And in fact, there's something else going on.

So, what scientists working in this area spent a long part of the last sort of chunk of the 20th century looking at was what the solution was to that problem.

So, what is the resolution to the bumblebee paradox in terms of how the aerodynamics are actually working on it?

And the answer really comes down to these things called vortices, which are left behind, behind a wing as it's flapping.

But if you're a delta-winged aeroplane, or if you're an insect, and in fact probably some birds and bats too, then you have one of these vortices sitting over the top of the wing.

And when a vortex is sitting over the top of the wing, that reduces the pressure on the top surface and it provides you then with extra lift.

Can you say, okay, well now we know how nature does it, why don't we take some of that and then build aeroplanes that have the same sort of messy air over the wing?

There are plenty of examples actually of ornithopters, so that's that's little vehicles that flap their wings like insects and yes, there are some really quite small versions of these things that can buzz their wings rather like a bee does.

So there's some experiments on little robots from Harvard.

Robot bee.

Robot bees.

How big is a robo bee?

Tiny.

Size of a penny.

And how far can it go?

Able to cover two kilometers

in a 25-minute burst.

Why would you want a robo-bee?

Because you want things to get into small places.

So you can use them to go into like collapsed buildings and things like that.

So very good at getting into parts that humans can't go.

Is it about its agility then as well as its speed and distance?

I think the difficult thing with all of these is it's actually not that hard to produce the thrust to push itself forward.

The difficult bits always control and doing something useful with that control and agility that you've got.

You really need to be able to do useful things like intercepting a target.

So feeding back the information that you have on how the target's moving, using that to structure how you turn, that's where the challenge really starts to come in.

And being able to do more than just take off, that's where the really difficult part comes.

That and also having enough additional payload that you can carry to have all the sensors that you're going to need to do these interesting tasks, like being able to take imagery, if that's what you want to do, to go into a building and find people that might have been trapped in an earthquake or something.

But okay, surely to have the kind of agility that you're describing, to be able to manoeuvre, to detect obstacles and avoid them, requires some sort of cognition.

Like, does it, is that not, I mean, even aside from just the physical effort of flying, there must be...

Yeah, well, I think that's the interesting question because I don't think the really interesting bit to begin with is copying flapping flights.

It's copying all the other bits that are wrapped around that.

So if you take this example of being able to intercept a female with having eyes that have become enlarged in a way that is particularly specialised for that task, these horse flies that we were looking at before, they're not doing clever cognitive tasks with the eyes necessarily, where they've evolved to have these eyes that join at the top of the head so they've literally got a larger bit to look at females and chase after them they're using that for one very specific task and it's chasing females So typically what insects have for doing these chasing tasks is things called small target motion detectors, which is a kind of neuron which is wired up specifically to detect something flying across your field of view in about the right place.

And it needs to be flying in about the right place on your field of view.

It needs to be flying about the right angular speed across your retina.

And it needs to be about the right size.

So you've got a neuron which is specifically matched to detect things things that look like females at a range at which you can catch them.

And if it is the case that Jerry Butler's horsefly did manage to catch a little pellet fired from an air gun, that's what it would have been doing.

So as humans we go in with a problem to solve, we come up with a load of sensor measurements, we find a way of optimising the output of that and we tend to use quite heavy computing to do so.

But in insects where you've got these challenges in terms of the amount of energy that they can gather and wanting to maximise efficiency, what you do instead is to have processing that's tuned to particular things that are relevant to you.

So the secret really to having this kind of small brain is to have it tuned to do very specific tasks.

And if there's something interesting that we can take from insects across to the way that we build vehicles, I think it's that.

You know, we think about it so much before we do something.

The fact that they don't, if it's almost innate, means that they can shift quickly because they either want food, avoiding being food, or want to find a mate.

And if they can't change and react quickly in a three-dimensional environment, which, you know, they're gone.

I want to go back to that idea that Dara had in the beginning of you eyeballing a horse fly as you're driving down the motorway, which sadly we now realise is not possible.

There are some creatures that can fly that fast, right?

There are some creatures where

you could be having a head-head race with them down the M1.

Yeah, so if we want to find things that are flying faster, then we're going to need to look for things that are a bit bigger.

And so that takes us quite neatly to think about birds.

And there really are birds that can fly faster than I drive on the motorway.

So if you're a peregrine peregrine falcon, the fastest recording stooping speed of a peregrine is 242 miles an hour.

Now that was recorded in some rather artificial conditions.

So that was a peregrine that was released from a Cessna aircraft three miles up

with a skydiver and an altimeter so it was able to measure the change in algorithms.

When you see stooping is that heading straight down?

Yeah, so that's when you enter a

thrown out of the plane then.

I think it was doing it of its own accord, chasing after the skydiver.

In terms of what's been recorded out in the wild, it's probably closer to 100, 110 miles an hour.

So we've been filming peregrines chasing after prey.

In these dives, what you see is they'll close the wings and then they'll start beating them to increase the speed that they're getting.

And they're just constantly changing the shape of the wings through the course of this dive, which is then how they're able to manoeuvre in after the prey.

And is that how they catch prey, go above them and then dive down?

Typically, but they're very flexible birds.

So,

yeah, and different individuals will actually adapt to use different kinds of techniques because different techniques will work better on different prey types.

And individual birds will often be able to do that.

Did these guys ever dress as like a field mouse?

Is that how you lure the bird into a dive?

Yeah.

Or

a sexy pellet.

Yeah.

Thank you both, by the way, for coming in.

It's been an absolute pleasure to talk to you both.

Erica McAllister and Graham Teller.

Thank you very much indeed.

Delight.

I'm delighted to dispel a myth.

That's really important about the 90 miles an hour.

But I'm also happy to create loads more about how cool flies are.

Are they myths or are they just myths?

Still from the perspective of your fly phobia.

Nice factoids.

And yeah, okay, I'm not saying it's going to stop me chasing the flies in the kitchen, but I will have a moment of pause where I will reflect on how amazing their aerodynamics are.

I think that's all we can ask for.

Yeah.

I mean,

I've got a brief stay of execution before I take out the electrified tense racket.

And that's the end.

Subscribe to Curious Cases on BBC Sounds and make sure you've got push notifications turned on and we'll let you know as soon as new episodes are available.

You can manage your subscriptions from the My Sounds tab.

Imagine a scrap of data that could help rescue a man lost at sea.

That far north, most people aren't found.

This is a race against the clock.

Or expose staggering financial fraud.

All the Swiss banks, the British banks, the French banks.

What I was looking at was a horror show.

Or uncover a medical breakthrough.

Within 10 years, the whole world was convinced that he was right.

10 extraordinary adventures of data and discovery.

Uncharted with me, Hannah Fry, on Radio 4.

Now available on BBC Sounds.

At the BBC, we go further so you see clearer.

With a subscription to BBC.com, you get unlimited articles and videos, hundreds of ad-free podcasts, and the BBC News Channel streaming live 24/7.

From less than a dollar a week for your first year, read, watch, and listen to trusted, independent journalism and storytelling.

It all starts with a subscription to BBC.com.

Find out more at bbc.com/slash unlimited.