How To Eliminate Fire Ants in the Garden

I ran into a reader last week who asked me how to get rid of fire ants in their garden. I haven’t written about this subject in a while, so it’s probably a good time for a refresher.

Fire ants don’t really harm plants directly. But they have a bizzare symbiotic relationship with aphids, which do harm plants. Fire ants tend to aphids much like a dairy farmer tends to cows. They protect them from predators like lady bugs. The aphids allow the ants to “milk” them for honeydew, which the aphids extract from plants. By protecting them, fire ants can allow the aphid population to explode.

Besides, it’s no fun to kneel downinyourgardenandgetbitten by ants. I don’t like spreading toxic chemicals among the vegetables I eat in my garden. Thankfully, there is a non-toxic solution to the fire ant problem: drenching the mounds with orange oil and molasses.

Add about two to three ounces of orange oil to an equal amount of horticultural molasses and mix this into one gallon of water in a watering can. You will need a can that pours a solid stream of water, not one with a shower head (although many watering cans allow you to unscrew the shower head).

Walk up to the ant mound gingerly with the watering can in hand. Don’t stomp around or make a bunch of noise. If they sense a disturbance, ants will burrow themselves and the queen deeply into the mound, and the drench may not reach them.

Start by pouring directly in the center of the mound. After using up about half of the mix, pour in a circular pattern to drench the outside of the mound. Large mounds may require two gallons of the mix.

Orange oil kills ants on contact. The molasses acts as a repelant to keep any surviving ants from re-colonizing the mound. It seems counter-intuitive; one would think sugary molasses attracts ants. Instead, the molasses feeds soil microbial life, which tends to repel ants, who seem to prefer building their mounds from poor soils.