What food is poisonous to ants?

Several foods and substances are poisonous to ants when ingested because they disrupt digestion, dehydrate them, or act as slow-acting toxins that workers carry back to the colony, though effectiveness varies by species and no food kills instantly without proper formulation. The most effective poisonous food ingredient for ants is borax or boric acid mixed with sugar, which is the active ingredient in Terro Liquid Ant Bait and is considered low toxicity to humans but lethal to ants, as worker ants eat the sweet borax mixture and carry it back to the nest through food sharing called trophallaxis, feeding the queen and larvae and killing the entire colony within days to two weeks. Other foods poisonous to ants include artificial sweeteners like aspartame in some reports, though evidence is mixed and not reliable for control. Some people use cornmeal or grits, claiming ants eat them and swell, but studies show this is largely ineffective and ants can digest them. Caffeine in high concentrations can be toxic to ants. Certain essential oils mixed with food like peppermint oil can deter feeding. However, the best poisonous food approach is commercial gel baits containing fipronil, hydramethylnon, or borax formulated to be highly attractive to odorous house ants and carpenter ants, because homemade mixtures often fail to be attractive enough or kill too quickly before being carried back. For safety, keep borax baits away from children and pets, place them near trails but not directly on repellent sprays, and combine with sanitation by storing other foods in sealed containers so ants are forced to eat the poisonous bait.