ANSWERS TO GO with Susan Smith
SAN MARCOS PUBLIC LIBRARY
625 E. HOPKINS ST.
512-393-8200
A friend told me Q that she used powdered laundry detergent to get rid of fire ants. She wasn’t sure if it actually killed them or if they just moved their hill. Can you find me something on that subject?
I didn’t find A. any reference to powdered laundry soap, but I did find newspaper articles that mentioned Dawn dishwashing soap and orange oil. Most of the information below came from a Dallas Morning News online article published on May 14, 2018.
This article reported on the work of entomologist Nathan Riggs. Riggs worked as a researcher for Texas A&M’s Imported Fire Ant Research and Management Project. He also started “Antman’s Hill,” a Facebook page on insects and gardening. I believe he is currently based in San Antonio.
Riggs suggests a solution of orange oil, Dawn dishwashing liquid soap, and water. The soap melts the ants’ waxy covering and the orange oil starts dissolving the skeleton. Riggs reports that it worked about 75% of the time.
Orange oil and other citrus oils contain a chemical called D-limonene, an effective ant killer. It can often be found in garden centers.
Mix 1.5 ounces of orange oil, available at many nurseries, with 3 ounces of Dawn in a gallon of water. A second application may be needed.
Riggs recommends a ‘sneak attack” early in the morning or late in the afternoon. Don’t disturb the mound. Just pour the mixture over the mound until it’s saturated.
First warning—watch out for angry ants swarming out of the hill.
Second warning—orange oil will kill plants. Be careful to pour the mixture only on the mound.
For particularly serious infestations, the A&M fire ant research project recommends a two-step approach. First, use a broadcast bait with insecticide. These cover the entire area and will kill ants when workers feed it to the queen. Follow package directions carefully. People often apply too much. Some baits call for only a pound per acre and much less for a standard suburban backyard.
If individual mounds remain after a couple of weeks, apply a mound drench, like the citrus oil-soap mixture.
Nathan Riggs’ work on fire ants is widely quoted. If you Google his name and fire ants, you will find quite a few interesting articles.
I always like to confirm things I find on the Internet. The website of Texas A&M’s agriculture department is one of my favorite sources.
Their Texas Imported Fire Ant Research and Management Project provides answers to a wide array of fire ant questions: fireant.tamu.edu/manage/faq.
