Are coffee grounds a good ant repellent?

Coffee grounds are sometimes touted as a good ant repellent in home remedy forums because of their strong smell and caffeine content that is said to deter ants, but scientific evidence shows they have limited and inconsistent effectiveness as a repellent and do not eliminate colonies, so they are not considered a good primary ant repellent by pest control professionals. Some people sprinkle used or fresh coffee grounds around entry points, garden beds, and ant mounds hoping the strong odor will disrupt pheromone trails and deter odorous house ants and other species, and there are anecdotal reports of temporary reduction in foraging. However, studies on coffee grounds as ant repellent show mixed results, with some species avoiding them briefly while others ignore them or even nest near them, and the repellent effect fades quickly as grounds dry out and lose smell, especially outdoors in rain. Caffeine can be toxic to ants in high concentrations in lab settings, but the amount in used grounds is too low to kill colonies, and ants can simply walk around treated areas if food is attractive enough. Coffee grounds also do not kill the queen or eliminate the nest hidden in walls or soil, so new ants continue to appear. Additionally, coffee grounds can mold and attract other pests if left damp indoors. For effective ant control, integrated pest management is better, including sanitation by storing food sealed and cleaning crumbs, sealing entry points with caulk, fixing moisture issues for carpenter ants, and using slow-acting gel baits containing fipronil or borax such as Terro that workers carry back to kill queen and colony within days to weeks, rather than relying on coffee grounds alone.