What won't ants cross?

Ants will not cross or will avoid crossing several barriers that disrupt pheromone trails, irritate their bodies, or present physical obstacles, though no barrier is 100 percent effective against persistent colonies and determined ants will often find gaps if food is attractive enough. Common household substances ants are said to not cross include chalk lines because calcium carbonate is said to disrupt trails, though studies show limited effectiveness, cinnamon powder which has a strong spicy smell that irritates and can block trails temporarily, black pepper and cayenne pepper which irritate, baby powder or talc which clogs their breathing pores and makes surfaces slippery, diatomaceous earth which dehydrates insects when they walk through it and is more lethal than just a barrier, coffee grounds which some ants avoid due to strong odor, and white vinegar or lemon juice solutions which erase pheromone trails and have strong acidic smells they dislike. Physical barriers ants will not cross or have difficulty crossing include sticky barriers like petroleum jelly, Vaseline, or Tanglefoot applied around table legs and cords, double-sided tape that traps them, and water moats, which is why placing pet food bowls in shallow water prevents ants from reaching them because ants cannot swim and avoid water, though they can form bridges with their bodies in large numbers. Ants also avoid crossing very hot surfaces and strong chemical repellents. However, odorous house ants and carpenter ants are persistent and will often cross these barriers if the line is not continuous or if they find a gap, so most effective control is integrated pest management including sanitation, sealing entry points with caulk, and gel baits.