While you may not think much at all about a few ants on the sidewalk, an invasion of ants during a cookout or inside your home is another story altogether. Lines of regular chalkboard or sidewalk chalk help keep those annoying ants at bay.

How Ants Find Food

Ants rely on one another to find food, or specifically, the scents left behind by other ants. This is why groups of ants are often found traveling in lines or along specific pathways toward a destination, such as a piece of fruit dropped on the ground during a picnic.

Ants are following pheromone trails left by other ants that recently visited the area. They tend to follow the strongest or most recent scent trails. Over time or when the scent trail becomes disrupted, ants have a harder time following the trail.

The Ant and Chalk Lines

Chalk lines on a sidewalk contain a finely ground version of calcium carbonate. This fine powder, if drawn in a thick enough line across an ant's scent trail, could confuse the ants. Drawing lines around a patio table and chair set or in front of potential entry points to your home could keep ants away, at least for a while.

The powder disrupts the ants' ability to pick up on the scent of other ants. In many cases, the ants won't cross the chalk line and will backtrack a bit, trying to pick up on the scent trail left by preceding ants.

A chalk line works best when fresh and thick and when it directly interferes with an existing or potential ant trail. For instance, a ring of chalk drawn a few inches away from and around a piece of watermelon on the ground may keep ants away, at least for a while.

Using the Chalk

If ants are indoors, try to locate their points of entry. Perhaps they followed a path beneath a partially opened screen door or through a tiny gap beneath a window screen's frame.

As you devise a way to prevent future ant entry, draw a chalk line, ideally outside the house, that crosses the ant scent trail. The chalk may also come in handy for a temporary line on a countertop, leading toward the kitchen sink or other places the ants find interesting.

Lines of baking soda may be used in place of chalk to keep ants away. Baking soda works best indoors, as there's no chance of it blowing away. When using either chalk or baking soda outdoors, reapply the powdery substance whenever it wears away or blows away or after rain. In either case, the solution is only temporary.

Getting Rid of Scent Trails

Blocking the ants' scent trails doesn't prevent ants completely. The best way to get rid of them is to clean up whatever is attracting the ants, such as spilled jelly. Wipe down the entire ant trail area with soap and water or with equal parts water and white vinegar. Once the source of interest and the scent trails have been eliminated, the ants will look elsewhere for food.

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