I found two flies in my house, marked them, then later found two more flies without marks. I think this means the population of flies in my house is infinite.
I have a valid reason to outlaw humour.
Because of you comment 3 things have happened.
1) I snorted, causing my hot tea to use my nostrils as an emergency exit.
2) My nose became a tea tap.
3) My screen and keyboard, bless them, are covered with tea. My shame in cleaning it up is indescribable.
Bravo.
Closely related (though not quite the identical problem): https://www.johndcook.com/blog/2010/03/30/statistical-rule-o...
Applying that directly, we would estimate that the odds of a fly in your house being marked are less than 150%, which tells us that you should be taking larger samples.
(With only two marked flies, this estimate will always be less informative than the fact that you sampled n flies -- it will tell you that the population is probably greater than 2/3 of n, while the sampling procedure tells you that the population is necessarily at least n+2. But as you mark more flies, the estimate will be more informative.)
By the rule of three, we estimate the probability that a fly in your house is marked at p < 3/100.
We can also model the probability that a fly in your house is marked as 100/n, where n is the number of flies in your house.
Then 100/n < 3/100 and n > 100*100/3 = 3,333. There are probably more than 3333 flies in your house.
The next day, same story. The flies were now appearing throughout the day. They all looked the same. Where the hell were they coming from? The windows were still closed. I kept vacuuming.
Eventually things were starting to get very irritating. I hunted for an entry point for days without finding anything and the flies just kept on appearing. I was pretty good at vacuuming flies by this point.
By day six I spotted a group of them hanging out near my Kentia palm. Aha! A fly had laid eggs in the soil of the plant. I had no idea that it was a suitable food source for larvae. Needless to say I quickly filled it with gravel and I guess that's the story of how I became a qualified Fly Detective.
Catch one in a cup or plastic bag and stick it in the freezer for about 10 minutes. When you take it out it will look dead, but it's not (unless you leave it in too long.) Being careful not to rip it's wings off, tie a small string or fishing line to one of it's legs.
In a few minutes it will thaw and start to walk around, and then start to fly. You can now walk it around the park like you were carrying a balloon.
I think repeatidly slapping them with a pretty soft plastic attraption until they stop moving is even harsher though.
Or slapping them outta the air, trying to electrocute them but having too little power on the shitty device so only their wings get burned.
Or vacuuming them up
Or flushing them down the drain.
Honestly, whatever people usually do to them it's way way crueller
It's soft to you, not to the fly. You don't slap a fly "until it stops moving". When you swat a fly, it explodes.
Don’t Google dust mites.
Because of their rarity, I find that the ones that wear tiny top hats are easily distinguishable too.