Do ants have a "stay away" signal?
It is a long time since I set in a Computer Sci (AI) talk about this….  This explains it a bit.


Once ants have eaten they return to the nest.
On the way back to the nest they put down a scent.
This scent fades with time.
Most ants follow the scent.
(A few ants walk randomly to find new food, or a new faster way to the current food.)


So if the agents eating your poison bait do not make it back to the nest, there is no scent trail leading to the poison for more ants to follow.     But the ants that went round the bait to find other food, did make it back to the next, so setup a new sent trail.

If a poison kills the ants quickly, the customer is likely to see dead ants and therefore buys more of the poison.   However a poison that kills the ants slowly, so the ants don’t die until they get back to the next, is likely to get more of them, as there is now a strong sent tail to the poison.