The Red ants belong to a massive family that have small nests all over the yard but are all one family.
I experimented with different types of baits, I tried sugar based baits and oil based baits and I found the red ants mainly eat oil based baits, I experimented with the amounts of Boric acid and the types of oils and peanut butter, I found peanut butter base was best, I also added vegetable oil too make it more oily and that worked very well also, but I mainly just use peanut butter and Boric acid.
Boric acid is slow working but that is the idea, if it killed them fast they would stop eating the bait, but because it kills them slow they have no idea what is going on, it can take weeks for them to stop coming to the baits, I have just finished killing all the brown ants in my yard, I noticed they even came in from next door too the baits.
The Black ants have also been a pain, I have tried many times to kill them but now all the black ants have disappeared, I have not seen any black ants at the baits I usually give the black ants sugar based baits.
I'll give you my recipes for the baits.
Oil based bait is ½ teaspoon Boric acid and 1 heaped teaspoon peanut butter.
Sugar bait is 1 teaspoon Boric acid or Borax to 6 tablespoons white sugar to 2 cups boiling water, I have also used honey, you can put cotton wool or a stick in the liquid for them to climb on without drowning.
With the oil based bait you have to stir it now and then as they suck all the oil out and leave powder on top.
The pics are when the ants were nearly all gone, originally you could not see the peanut butter for so many ants in all the baits.