How many flies are in my apartment? • Hacker News Board

Re: How many flies are in my apartment?

#61

Post by mannykannot » Fri, Jun 18, 2021, 12:51 PM UTC

Lévy flight foraging hypothesis: https://en.wikipedia.org/wiki/L%C3%A9vy_flight_foraging_hypo...

The scent-tracking mode used here seems to be a sort of variant, in which the long legs are not chosen randomly.

WRT the insect density decreasing as some fly away: in reality, others will arrive at approximately the same rate, keeping the density approximately the same, so it is probaby more realistic to put a box around the simulation, e.g. by reversing the direction of those that have moved away to the point that they would be several time-slices away from entering the window even if they flew back in a straight line.

Re: How many flies are in my apartment?

#62

Post by OJFord » Fri, Jun 18, 2021, 12:54 PM UTC

morelisp wrote: post #22

only_as_i_fall wrote: post #19

Earlier quoted context omitted.

Dont the windows have screens? In the US pretty much every window has a permanent screen outside the panel for this purpose...just assumed it was the same in europe

They do not, and it's unfathomable why. One of the first things I did after moving to Berlin was put screens on our major windows. My European friends constantly complain about insects coming in (wasps are a big offender in Berlin - and technically you can't kill them) but for some reason never just put up a screen.

Because I don't want some ugly thing strapped to my window?

Because I want to let more light in?

Because things flying in is approximately not a problem anyway?

Seems perfectly fathomable to me.

(I live in London, occasionally a fly will come in and chill out for a bit before sodding off again.. fine? I've never had a wasp inside even. Our mosquitoes will extremely rarely give you anything nasty. Moths that would fly in aren't the fabric-eating kind. Even leaving aside the other issues, there's no reason to, it wouldn't be worth my time or money to buy them/fit them/have them fitted. I've spent longer writing this comment than being irritated by anything flying in through my windows.)

Re: How many flies are in my apartment?

#63

Post by tk75x » Fri, Jun 18, 2021, 12:54 PM UTC

morelisp wrote: post #22

only_as_i_fall wrote: post #19

Earlier quoted context omitted.

Dont the windows have screens? In the US pretty much every window has a permanent screen outside the panel for this purpose...just assumed it was the same in europe

They do not, and it's unfathomable why. One of the first things I did after moving to Berlin was put screens on our major windows. My European friends constantly complain about insects coming in (wasps are a big offender in Berlin - and technically you can't kill them) but for some reason never just put up a screen.

Why can't you kill wasps?

Re: How many flies are in my apartment?

#64

Post by OJFord » Fri, Jun 18, 2021, 12:57 PM UTC

tk75x wrote: post #63

morelisp wrote: post #22

Earlier quoted context omitted.

They do not, and it's unfathomable why. One of the first things I did after moving to Berlin was put screens on our major windows. My European friends constantly complain about insects coming in (wasps are a big offender in Berlin - and technically you can't kill them) but for some reason never just put up a screen.

Why can't you kill wasps?

This calls it a 'myth', but really concludes that it's hyperbole arbitrarily calling out wasps; they're technically a protected species and you could be fined but.. almost certainly not going to happen for one or two wasps bothering you at a cafe or whatever?

https://medium.com/@sophanemwise/the-wasp-killing-myth-in-ge...

Re: How many flies are in my apartment?

#65

Post by thearn4 » Fri, Jun 18, 2021, 1:01 PM UTC

mkreis wrote: post #46

m12k wrote: post #40

In my statistics class we were taught a technique for estimating the number of flies in a barn. You capture a fixed size sample of flies, e.g. 100, and give them each a little white dot on the back, then release them all back in the barn. Leave them to mingle for a while, then capture another fixed number of flies, e.g. 100. If 5 of them have a white dot on them, then you estimate that the 100 flies you captured orig…

Reminds me of how the Allies estimated the production capacity of German tanks during WW2: https://medium.com/dataseries/how-data-science-gave-the-alli...

Great read!

In comparison, I have to wonder why the "intelligence estimates" were so bad/severe over estimates.

Re: How many flies are in my apartment?

#66

Post by NorwegianDude » Fri, Jun 18, 2021, 1:08 PM UTC

I was really confused about where this was going when I started reading as I thought the title sad files, not flies...

Re: How many flies are in my apartment?

#67

Post by Aachen » Fri, Jun 18, 2021, 1:30 PM UTC

pharmakom wrote: post #3

Is it better to leave windows open so flies can escape or closed so they never come in?

Window closed means no flies could ever come in, whereas with an open window it's a possibility. So purely from a statistical point of view...

I've never noticed the number of insects reducing from open orifices, only increase, presumably until it's the same number per m³ as outside (or higher if you have food out, perhaps). I won't rule out that there might exist configurations where flies are more likely to fly out of than in to, but aside from conical shapes designed to do that (i.e. not regular windows), has anyone ever noticed that opening a window reduced the number of insects inside?

Re: How many flies are in my apartment?

#68

Post by mncharity » Fri, Jun 18, 2021, 1:33 PM UTC

fmax30 wrote: post #8

codetrotter wrote: post #4

Earlier quoted context omitted.

Open windows for air, but have a finely masked net covering the opening so insects don’t get in.

This is the norm in the south asian country I come from. But ever since I moved to the EU, there have been no nets, then again there are noticeably fewer flies here too.

Differences in regional naming and screen types are causing confusion in nearby comments.

A screen door can be a secondary exterior rigid door with metal mesh panels[1], or a hanging fabric mesh door[2]. A window screen can be a metal mesh, in a rigid metal frame, tightly integrated with a window[3], or a flexible add-on[4].

The polyester/fiberglass/etc fabric meshes can be more opaque than the metal ones.

[1] https://upload.wikimedia.org/wikipedia/commons/2/22/Screen_d... https://www.lowes.com/search?searchTerm=screen+door [2] https://www.alibaba.com/trade/search?fsb=y&IndexArea=product... [3] https://www.youtube.com/watch?v=oEdK5h6smTU [4] https://www.alibaba.com/trade/search?fsb=y&IndexArea=product...

Re: How many flies are in my apartment?

#69

Post by jmiserez » Fri, Jun 18, 2021, 1:33 PM UTC

m12k wrote: post #40

In my statistics class we were taught a technique for estimating the number of flies in a barn. You capture a fixed size sample of flies, e.g. 100, and give them each a little white dot on the back, then release them all back in the barn. Leave them to mingle for a while, then capture another fixed number of flies, e.g. 100. If 5 of them have a white dot on them, then you estimate that the 100 flies you captured orig…

My first ever job (in high school) was manually counting mosquito larvae in water samples for our local department of agriculture. IIRC the aforementioned technique doesn't really work for that, instead they collected samples regularly for several months at the same spots each year and used that for their forecasts.

Re: How many flies are in my apartment?

#70

Post by qwertox » Fri, Jun 18, 2021, 1:34 PM UTC

Next step is to set up a grid of ESP32s with MEMS microphones and a FFT routine, stream that data to a server and apply some neural network to get to know the real amount of flies by tracking them individually. Then compare this to the model, and keep improving it until it fits.