a clear plastic container that you can poke small holes into the of,
a straight pick or equivalent to poke those holes,
common white vinegar ($5ish for a gallon,
dishwashing soap
Poke holes evenly in the top of lid. Put a bit of vinegar in the container (e.g. a lidded condiment cup you can probably get from your supermarket, or a fast food drink cup), add a few drops of dishwashing liquid, put the lid on and put it where the flies are.
That’s it. Scale the size of the container to the number of flies, and a clear container lets you easily see the amount of flies trapped, but doesn’t strictly need to be clear. Set up more traps if needed. Hope that helps.
What worked for me is pretty simple and cheap:
Poke holes evenly in the top of lid. Put a bit of vinegar in the container (e.g. a lidded condiment cup you can probably get from your supermarket, or a fast food drink cup), add a few drops of dishwashing liquid, put the lid on and put it where the flies are.
That’s it. Scale the size of the container to the number of flies, and a clear container lets you easily see the amount of flies trapped, but doesn’t strictly need to be clear. Set up more traps if needed. Hope that helps.