Borax and boric acid, when mixed with sweet foods, are effective at killing sugar ants. Borax and boric acid are both toxic to sugar ants but relatively harmless to humans and pets.
Mix borax or boric acid with sugar, mint jelly, honey or other sweet foods or liquids. Dissolving the poison completely into the sugary food is imperative since the ants have to ingest the poison for it to affect them. After preparing the poison mixture, apply it to areas where the sugar ants congregate as well as near their nest if possible. Once the ants ingest the poison mixture, they carry it back to their colony, killing both themselves and any other ants in their colony that ingest it.