i posted this in the other thread:
Locate the entrance of a nest and place an upturned pot over it - use a clay pot which will not be blown away. After a few days the ants will have migrated to the surface with their white larvae and they can be swept up.
Boric acid is toxic to ants and many other insects as it attacks their nervous system and causes dehydration so a 50:50 mixture with icing sugar makes a bait which will be taken to the nest where it should destroy the colony. It is an ingredient in many commercial products and has been used for centuries as an insecticide, a flame retardant, an antiseptic and in food preservation, so it is relatively non-toxic to humans and their environment. The nest can be located by following the returning ants, or quite often it is found while working in the garden when a stone is turned over.
They do not like peppermint so place it where you don't want them to go, or at their nest. Peppermint extract in water can be applied to surfaces.
If an ant is squashed clean the spot well as the corpse will release pheromones which will attract others. It is best to use a vacuum cleaner to remove unwanted ants.
A circle of petroleum jelly around the entry point will halt their journey, and if bait is placed within the circle they will take it back to the nest.
Another deterrent is ground cinnamon which can be sprinkled around to keep them out.
Instant coffee placed at the entrance of a nest and repeated a few times will see them off.
Diatomaceous Earth could be described as a biological control although the active agent is no longer alive since it is the fossilised remains of diatoms - tiny algae. It works by sticking to the exoskeleton of the ant by electrostatic attraction and abrades it as it moves around resulting in holes which lead to dehydration and death. It is applied as a fine powder to paths and around nest openings.