As more and more ants travel the same area they will leave a scent and sign that other ants will follow even though you killed the head scouts and workers last week.
Instead of spraying the ants and killing just a few of the ones you can see right now, use a good quality ant bait (quality level is discussed in an earlier blog post here).
It is important you DO NOT spray near the bait though. The ants are smart enough to recognize the spray as toxic and will not take that back to the nest. That is the key goal here, to provide a better, easier to carry bait than drew them into your kitchen area in the first place.
Often these indoor ants are small. So grind the bait granule to a size you think will be attractive to them. NOT a dust because that would not be enough to be worth carrying back to the nest, but small enough to get in small spaces.
I had a Pet Clinic with a problem in one area that no one seemed to be able to stop. I laid on my side watching them for an hour, followed their foraging path and found that they were trying to get under a piece of molding that was very tight to the floor. There was discarded large granules all around the area as they gave up and went back for something that would fit. I ground the bait until it was a size they could get into the nest and have not had a problem there since.
So if you are having a reoccurring ant problem, you need to find a way to be ready to kill that nest and any new nest that arise with the right size ant bait for the right size ant.
