Chalk Lines Stop Ants from Crossing

The Problem

Ants keep coming in through the same crack or gap under the door.

The Hack

Draw a thick line of regular chalk (or sprinkle powdered chalk) across the ant entry point and along the threshold.

Why It Works

Chalk contains calcium carbonate which disrupts ant pheromone trails and creates a physical barrier they avoid. The fine powder also coats their feet and interferes with their ability to grip surfaces.

Pro Tips

• Reapply after rain or mopping
• Cinnamon powder works the same way
• Seal the entry point permanently with caulk
• This is a temporary barrier while you address the colony