Why Won't Ants Cross a Chalk Line?

June 20, 2021


With the rise of social media and video sharing platforms like TikTok, videos showing the inability of ants to cross a chalk line or ants not being able to cross a line drawn by a pen or marker have gone viral. Upon further investigation, this myth has been debunked.

Ants are very sensitive to pheromones, a chemical substance they produce and release into the environment. When a pheromone trail is disrupted by chalk or a line drawn in their path, the scent trail they were following is temporarily disrupted. While ants will turn away in an attempt to find the pheromone trail again, as soon as these videos end the ants likely find their way back onto their original path.

Why Won't Ants Cross a Pen Line?

For the same reason ants won't cross a chalk line. Their pheromone trail is being temporarily disrupted, causing them to search in a different direction to find the trail again. 

If drawing chalk lines and pen lines was such an easy way to stop ants, we'd definitely incorporate it into our home pest control programs! As fans of pet safe pest control, a chalk line would be about as pet safe as it can get for ant control.

How Do Ant Pheromones Affect Pest Control?

While finding out why ants won't cross a chalk line is neat, it is actually very important for pest control technicians to understand the concept of ant pheromones and how it affects the ant control methods they use for residential and commercial pest control. 

Many homeowners and untrained applicators are conditioned by product branding to apply contact kill sprays purchased at big box stores when they see ants in their home. What most don't realize is that just like a chalk line drawn in front of an ant trail, these sprays affect the pheromone trails ants follow and can actually split ant colonies in a process called budding. 

Species of ants like Ghost Ants which may have one queen in your home may then separate into two or three colonies with multiple queens as a result of the incorrect spray being used to exterminate them. Instead of solving your ant problem, this may have made the number of ants in your home increase and can often spread the ants to different rooms of your house as well. 

At Native Pest Management, we avoid products for ant control that affect the ant pheromone trails. We use non-repellant products that ants don't know is present, so ants will walk right over the products we apply and inadvertently pick it up on their bodies. This in turn allows them to carry it back to their colony, eliminating the queen and the entire colony and solving your ant problem for good.

So while you started this article reading about why ants don't cross chalk lines or pen lines, you ended up learning why products like Raid and Ortho also affects the pheromone trails ants follow. Hopefully this helps you eliminate any ants you have in your house. If not, call us today for a free pest control inspection in West Palm Beach, FL and surrounding cities including Fort Lauderdale, FL, Miami, FL and Port St. Lucie, FL.

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