You do not usually see the scout ants. These ants are small and not easily seen as single scouts, and when you see one ant you don't usually pay much attention. But wait for that scout ant to find a food source in your sink, on your countertop, an open container in a cabinet, or perhaps a plate of cookie crumbs left beside the bed. The scout ant leaves a trail by touching its belly to whatever is being walked on. That chemical trail left by the ant is like building a one-lane highway. Every ant getting on the trail adds his chemical to it. The trail soon becomes a 20 to 100 lane wide freeway, with ants coming and going. Vacuuming up the ants does not destroy the chemical trail; the ants will keep coming until the chemical trail is destroyed, the food source is removed, or you have the ambition to sit there and vacuum up the whole nest's population.
Interestingly, those dumb ants also improve their trails over time to shorten the trek in travel time and distance, thus making the food source more efficient to access. Ant research has been used to improve product flow efficiency by distributors such as Amazon, Ebay, UPS, FedEx, etc. The ants do it instinctively. We learned it from them. Ants were here millions of years before humans. These efficiencies have been given to them through natural selection, an aspect of evolution. We have to consciously build efficiencies.
One other thought: I have used encapsulated Diazinon on yellow jacket wasps with success. I do not know if such a product is made for ants. The idea is the poison is encapsulated inside a cover of insect food. The insects carry it back to the nest where it is eaten by those immoral ants "working" in the sex gangs. That's work, huh? The nest dies quickly using this poison recipe.
