put a small amount of semolina/polenta in shallow container,place where the ants are active,apparently the ever dutiful workers take it back to the nest and feed the queen,she cannot digest it,so explodes,so no queen,no more workers,thats why you have to be patient a few days,if they come back,repeat,and yoes,this does work.maybe it would work with other food stuff that is of the same sort of make up.