Not as stupid as it sounds - I really want to know where do these ants come from. If I leave some crumbs on the kitchen bench and come back a few hours later there will be a few hundred tiny ants swarming all over the area, BUT, I have never found their home, I never see a “trail” of ants back to anywhere, they are just running around the area where the food is and nowhere else. So where do they come from? Do they teleport in? Fly? Are they dropped there by ant bomber or what? And how do so many find their way - do they call out to each other or something?
This, at least, I can answer. They leave a scent trail along the path they followed, that other ants can smell and follow them. If you can figure out where the trail is, a chalk line will interrupt it.
Scout ants are adapted to find food just about anywhere. And they tend to have territories they return to if a hunt was successful in the past. Once they’ve found food, they take a bite, and go home with it. Their trail on the way home smells different to other worker ants, who then follow it back out to the source of the food. If I recall correctly, the scent indicates more than just “Food Thataway” but actually can indicate how much, and what kind.
For food that has to be left out (Cat food, etc) my parents used to place the food dish inside a water-filled saucer, so that there was a “moat” around it. This dramatically cut down on the frequency of ants in their house.
If you look carefully you will be able to see ants heading back to the nest. They may be well spaced out so they may be difficult to notice. However, they will all follow the same path over the scent trail. If they are still recruiting to the food source, some will be running toward the food, and some back to the nest.
I regularly get colonies of tiny sugar ants in my apartment. It can take a lot of patience to figure out exactly where they have their nest, but it can always be found by following the foragers back.
When I was a kid we used to wipe away the scent trail with our hands and then “redraw it” with a q-tip and some diluted lemon juice. I guess the mixture was close enough to the ant scent to fool the workers.
We would draw serpentine trails and designs and watch the ants follow. Loops were real fun but they seemed to learn quickly.
Yeah, sometimes we were bored.
And the amazing thing is that, given enough generations, ants can find their way just about anywhere. There are ants at the top of the Empire State Building.