
Why is it so hard to swat a fly? - jayflux
http://www.bbc.co.uk/news/science-environment-41284065
======
apl
As someone who works in visual neuroscience, this article's a tough read. Lots
of statements that are semi-accurate at best.

1) Eyes don't work like cameras; there's no real "exposure" phase as such
(even though there's lots of thresholds). So it's misleading to talk about
discrete images that we sample at some fixed frequency. Instead, it's much
more helpful to think of photoreceptors and subsequent processing stages as
continuous band-pass filters. At some point, high frequencies are simply cut
off because the electro-chemistry of the cell can't keep up. For us, that cut-
off comes earlier than it does for invertebrates.

2) There's no mechanical interaction between light and photoreceptor. Instead,
the transduction cascade of the dipteran eye seems to encompass a mechanical
(as opposed to biochemical) step.

3) It's pure conjecture to talk about a fly's slowed down "perception" of the
world. The reason why they take off before you get to them is much simpler --
there's a highly optimized reflex that connects eye and flight muscles via the
giant fiber (a particularly rapid nerve). We have similar responses, like eye
lid closing etc. Additionally, their photoreceptors are sensitive and fast.
But there's zero evidence that flies have any sense of continuous time that
could be faster than ours.

Ah, well. The perils of science journalism.

~~~
taneq
Thanks for the informed opinion. I know way less about animal vision than
machine vision but the statement that eyes have a "frame rate" and "send
images to the brain a fixed number of times a second" smelled really bad.

A maybe-dumb question about point (3) - I've noticed that when I get a
blink/flinch response from something (usually some sand or a bug hitting my
face when I'm on the bike), it _feels like_ I blink just a split second
_before_ the thing hit me. Given that I'm unlikely to have any kind of
precognition, do you think this might be related to the blink reflex being
'hard wired' and so my brain gets the "hey, a thing hit your face" signal
after the "hey, your eyes just closed" signal? (Alternately, I read something
once about our perception of audio being delayed by ~100ms so that it synchs
up with our perception of vision, despite our visual processing being slower
than audio - maybe the signal that caused the flinch gets 'buffered'?)

~~~
apl
> I've noticed that when I get a blink/flinch response from > something
> (usually some sand or a bug hitting my face when > I'm on the bike), it
> feels like I blink just a split second > before the thing hit me.

We know very little about conscious perception or even the locus at which
sensory signals are integrated to generate a conscious percept. But it's
perfectly possible that delays differ across modalities and that the
proprioceptive signal about lid-closing reaches whatever-relevant-area before
your visual system catches up.

> I read something once about our perception of audio being > delayed by
> ~100ms so that it synchs up with our perception > of vision

Not an expert on audition, but the brain is really good at generating coherent
representations of the physical world across modalities. I wouldn't be
surprised if such cross-sensory synchronisation happened in some form.

~~~
taneq
Cool, thanks for the response! I'm glad my theory doesn't sound /too/ far
fetched. :)

------
adekok
If you want to catch a stationary fly, it's pretty easy to do so with your
bare hands. The key thing to know is that they jump _backward_ before taking
flight.

Aim for a spot about 1-2" behind the fly, and about 1-2" above the fly. Try to
catch it _there_ , and your success percentage will be high.

~~~
wruza
The perspective of cathing a fly that walked on crap five minutes ago disgusts
me. I know they cleanse their paws more often than I do mine, but faugh.

~~~
adekok
1) catch a fly and wash your hands

2) see the fly walk over your food, your face, your kids food...

Do you want to touch a "dirty" fly, or eat what the fly has walked on?

I'll take #1 any day.

~~~
gbog
3) Do not care at all, and consider that our bodies are pretty well tuned to
handle such thing as a few particles of foreign excrement (or other dirty
things).

Seriously, we have become irrational animals afraid of everything. (I would
wash my hand after splashing a fly if there was a rotten corpse around,
though, and would have done even without the fly because my nose would have
alerted me of a chemical danger.)

------
i_feel_great
Three techniques: 1\. Move your open hand towards the fly very slowly until
you are 5cm (2 in) away then slap. 2\. Move both hands slowly towards the fly
and "clap" to catch it. 3\. Blow gently downwards onto the fly, then slowly
increase the force of the blowing. You might then be able to pin its wing to
the surface.

Yes, I have a lot of time on my hands.

~~~
roceasta
_> Yes, I have a lot of time on my hands._

Also a lot of fly goo.

------
j-conn
Check out the "bug-a-salt" salt gun. With good aim it's more effective and fun
than a flyswatter. Absurdly, amazon wouldn't ship to California but you can
buy from [https://bugasalt.com](https://bugasalt.com)

When swatting, I've found they can only fly forward and had good success
anticipating that movement. Apparently others in this thread can catch them on
the fly's initial backwards jump, which I had never noticed.

~~~
nemo1618
These are fun but I found them incredibly hard to aim; for me, the Bug-a-salt
was only effective when less than two feet away from the fly. (And the fly had
to be stationary -- no dramatic mid-air takedowns.)

------
delinka
Where’s the video of the killer fly catching a fruit fly? I want to see
_that_.

~~~
zeotroph
Also, what is the scientific name of the killer fly? There is no such article
on wikipedia.

And some more references on how compount eyes see _mechanically_ , as opposed
to chemically, would be interesting.

~~~
ximeng
[https://en.wikipedia.org/wiki/Asilidae](https://en.wikipedia.org/wiki/Asilidae)
maybe this one, although this video explicitly names killer fly:
[https://www.youtube.com/watch?v=ukiTGsvFP1Y](https://www.youtube.com/watch?v=ukiTGsvFP1Y)

------
fatjokes
I have perfected this. I can even stop them mid-flight.

Spray at it with any liquid (e.g. water, household cleaner). It may take a
couple of squirts but it's easy as it doesn't need to be exact. The fly will
fall to the ground where you can just squash it with a tissue.

~~~
baybal2
A more high-tech solution: [https://www.aliexpress.com/item/1pcs-Hot-
Worldwide-Electric-...](https://www.aliexpress.com/item/1pcs-Hot-Worldwide-
Electric-Insect-Fly-Mosquito-Zapper-Swatter-Killer-3-Net-Racket-
Rechargeable/32316697946.html)

~~~
fatjokes
Have one of those. They don't work.

~~~
baybal2
Must be bugs in firmware

------
japhyr
It's really easy to pick up flies with a hose attachment on a vacuum.

Every once in a while we get a number of flies in the house during the summer
when the doors and windows are open. They tend to gather in the sides of our
windows, looking for a way out. I used to catch them one by one, and then I
tried a vacuum. It was easy, once they are aware of the vacuum it's too late
to fly away, and they get sucked right up. It's probably not worth while for
one or two flies, but if you're going after a few a vacuum can be really
effective.

------
MPSimmons
Only partially related to this topic, but is anyone else driven crazy by the
Cadillac taillights? I haven't talked to anyone else who is, but I can
identify one from a mile away at night. It's like the refresh rate is just low
enough that it flashes and it drives me nuts.

------
tw1010
And why are flies found in the country significantly harder to swat than those
you find in the city?

------
grondilu
Because it's much more important for a fly not be swatted than for a large
animal to swat it.

------
subroutine
Differences in visual flicker-fusion rate between species is interesting. But
I think it's a bit presumptuous to claim that time drags by 4x more slowly in
a fly's reality, and that's why it can usually escape a giant hand falling
from the sky. The fly escapes because it's quicker than you. It would probably
be just fine if could detect motion at 60 Hz.

------
roflchoppa
Man you guys just approaching the problem the wrong way. I’ll tell you how
Mike D, a technitian at Apple taught me. You simply wait for the fly to land,
and then come at it from behind. The flys launch backwards when they take off,
so you can open hand catch them, perform the stun, and get them out of the lab
with all your open hardware.

I’ll never forget seeing Mike catch that fly.

------
lenkite
I really never had a problem catching flies and I don't even think I have fast
reactions. You just need to observe their flight silently for a few moments,
breathe subtly and make your move suddenly, preferably from the back. They are
amazing at avoiding hits from the front. Put yourself in the mindset of a
deadly, stalking predator instead of irritated house resident and watch those
kill counts stack up.

------
Agathos
After reading these comments, I'm starting to wonder if I'm the only one who
owns an old-fashioned flyswatter. With a long, stiff handle and a flick of the
wrist, it moves a lot faster than a fly. I've even stunned them by hitting
them in mid-air.

------
jesperlang
I've found it much easier to try and hit the fly mid air with one open palm,
rather than crushing it against a surface. If you hit it, it will be fall to
the floor dizzy/stunned. From there just pick it up with a piece of paper.

------
pasta
The article doesn't mention this but as I understand flies can only see
motion. So when you move very slow you can catch them.

It doesn't mean that they only see moving objects by the way. In flight they
see because everything is moving around them.

~~~
zeotroph
I thought that most (all?) eyes only see motion, just as you do not feel the
weight of your clothes anymore (or the presence/absense of your wallet in your
back pocket) after a while. But reading up on microsaccades[1] - tiny
involuntary eye movements which I thought fixed that in mammals - that does
not seem to be the current understanding anymore.

1:
[https://en.wikipedia.org/wiki/Microsaccade](https://en.wikipedia.org/wiki/Microsaccade)

------
dagaci
You will notice that flies do not generally flee from things swaying (plants
branches, curtains) in the wind, if you make a sway movement with your
swatting implement the fly will ignore you when your too close for it to
escape.

~~~
jwilk
... when _you 're_ too close ...

------
lolc
I keep my hand vertical when approaching the fly and turn it only when
accelerating for the swat. That way the approaching hand appears with less
dramatic increase in size which allows a quick approach without warning the
fly.

------
praptak
It's super easy with an electric fly swatter - it's like a small tennis racket
which kills on contact. They might see it with their super fast vision but the
racket is just too large for them to avoid m

------
grafelic
In my experience flies have much harder time avoiding a finger flick.

~~~
roceasta
Yes. Bring the hand close _very_ slowly, forefinger cocked... then....pow.

Other techniques I've employed: (1) cling film (saran wrap), (2) detergent
spray (slows em down; dispatch after 2-4 rounds), (3) vacuum cleaner nozzle
(they hunker down but are sucked in upon take-off)

~~~
jwilk
What do you do with cling film?

~~~
roceasta
Slow approach with a sheet 20-30cm wide held at opposite edges by both hands.
The film being transparent the fly sometimes doesn't notice it. Also a
convenient means of disposal.

------
simpsond
Anecdote: I find that towel snapping works well.

------
icantrank
not trying to be that guy, but I swat the fly dead 9/10 times. Mr Miyagi did
also train me, but I don't use the chopsticks like my moderated compardre
above.

------
NicoJuicy
Want to kill the fly with your hands, clap above it

------
zomg
after watching karate kid, i now catch flies exclusively with chopsticks. i'm
3,285 for 3,285!

~~~
ComputerGuru
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