Every so often, an email starts circulating claiming that club soda is the new, awesome thing in killing fire ants. "And it really works!" You've probably received it lately, if you subscribe to any gardening type email blasts, or have friends that do.
The most recent email is claiming to be touted by Walter Reeves on his Georgia Gardener radio program. It claims to use two cups of club soda, poured on the center of the fire ant mound. Since carbon dioxide is heavier than air, it will push all the oxygen out of the mound and suffocate the colony. The whole colony is supposed to die within a couple days.
Now, there's no environmental hazard to trying this, that I am aware of. It should not contaminate ground water, and doesn't harm beneficial insects, wildlife, humans, pets, etc. The bad thing is, it won't really harm your fire ants either!
In 2009, my colleague, Wizzie Brown (who also has a bugblog urban-ipm.blogspot.com), tested the club soda theory in field trials. The emails that have circulated don't site any scientific testing to back them up, so she decided to give it a shot. That way, when we are asked about it, we have a true answer, not just a hunch.
After replicated experiments, it didn't work. There were no ants climbing to the surface, gasping for breath, and no evidence that there was any control at all.
One thing you may find, is that the mound moves over a few feet because they are irritated. And for some, if that means moving into the neighbor's yard, that's control! I am definitely not one to argue with success, so if you've tried club soda and swear by it, keep it up! As researchers, we just can't recommend, endorse, or encourage management practices that we find in replicated field trials not be effective (it would be like claiming a diet pill will make you loose 20 pounds without ever testing its efficacy or safety).
In addition, Walter Reeves has since stated that he has not endorsed club soda as a sound treatment to fire ants.
If you are interested in learning more about our results with various home remedies (molasses, garlic, aspartame, and others), check out http://fireant.tamu.edu and peruse our IPM handbooks. All the field work we do is written up in those yearly handbooks. There is also information about successful and low impact options for fire ant management.