All highly effective organic programs include a short-term strategy and a long-term strategy. The short-term strategy for Fire Ants is mound treatment. Mound treatments eradicate the visible mound quickly. This is particularly useful when a mound pops up in a potentially problematic spot, such as a vegetable bed or an area used by your family or pets.
The long-term strategy is designed to repel ants from areas in the landscape were they are unwanted. This allows for some ants to survive, but will minimize their “pest” threat.
Fire Ants are considered a beneficial insect because they are predators of some pest species, so it is neither necessary nor desirable to eradicate all of them. The only time it becomes necessary to eliminate all Fire Ants from your landscape is when you have small children, outdoor pets, or livestock that could stumble across them unawares.
Overall, an organic program to manage Fire Ants is safer, faster, and cheaper than most of the synthetic chemical approaches. It’s also easy. And it doesn’t stink, which many commercial products do.
We personally do not use any synthetic-based RIFA treatments in our landscape. We find that this Organic Management Strategy is very effective. I find a mound occasionally, but RIFA is not even a minor pest in my landscape.
- Fertilome® ‘Come & Get It’ Fire Ant Killer and Greenlight® Fire Ant Bait are Spinosad-based. They are effective, but they can take several days to several weeks to completely kill out a mound, especially if it is a multiple queen mound.
- Gardenville Anti-Fuego is an orange oil-based mound drench. It is sold as a soil conditioner, not as a pesticide. It is very effective, and works within a few hours or days.
- Orange Oil Mound Treatment – the following DIY mound treatment is easy to mix and use. It is safe for people and pets to contact, but it should not be ingested.
2-oz Orange oil concentrate (pure orange oil, not orange oil cleaner)
2-oz Horticultural molasses
2-oz Liquid dish soap (do not use an anti-bacterial brand)
2-gal Water or compost tea
Mix all ingredients together in a bucket. Pour slowly around the perimeter of the visible mound, and then continue to pour slowly as you move in a concentric circle working toward the center of the mound.
This amount will treat two large mounds, or several smaller mounds. You will see piles of dead ants around the mound in just a few hours. One treatment is usually sufficient. Occasionally, a second treatment is required a day or two later in a nearby, smaller mound.
People often think that the ants have “moved”, but in reality, Fire Ants will often have more than one entrance. You have treated the main entrance, so they closed it up and began using a secondary entrance.
Earthworms that come in direct contact with this mixture will be damaged or killed, but there should not be many earthworms within the mound anyway since Fire Ants will prey on them.
Any easy way to organize your mound treatment is to get a bucket with a sturdy handle and store all of the ingredients in it along with a ¼ cup (2-ounce) measure dedicated to the mix. This gives you a “Fire Ant Bucket” that is always handy and ready to use.
Fire Ants detest molasses. Regular use of horticultural molasses in the garden will eradicate almost all Fire Ants. Molasses feeds beneficial soil microbes, resulting in a rapid increase in their numbers. Some of those microbes are antagonistic to the ants.
Fire Ants are not sugar eaters; they are attracted to grease and proteins. Direct contact with the molasses can kill the insect as well. They will ingest it as they groom themselves. They are unable to digest the sugars, which ferment and expand in their gut. Since they have a hard exoskeleton which cannot expand, they will die from the resulting damage to their internal organs.
You can apply molasses in one or more of the following ways:
- Dried Molasses – This product is horticultural grade molasses that is sprayed onto an inert, decomposable substrate like ground nut hulls. Broadcast DM throughout the landscape at a rate of 10 – 20 pounds per 1000 sq ft. You can use a drop spreader, a hand-cranked broadcast spreader, or just scatter it by hand. It is non-burning and has other beneficial effects so the application rate is not critical.
- Liquid Molasses – The liquid molasses we use in the garden is a specific horticultural grade byproduct of the sugar industry. It is not as thick as your food grade molasses, so it is easily mixed in a sprayer. It can be applied at the rate of 1 – 3 tablespoons per gallon of water. You can use a pump sprayer, but it is much more efficient to apply it in a hose-end sprayer. Make two applications, one week apart to start. After that, you can make applications once or twice a month.
- Organic Fertilizers – Several good brands of slow release organic fertilizers contain DM. Arbor Gate Organic Blend, Microlife, and Gardenville are all good brands. Regular use of SROF containing molasses will make a noticeable difference in reducing Fire Ants in your garden.
What not to use
There are some urban legends and old wives’ tales about Fire Ant control. These methods are either ineffective or, in some cases, harmful.
- Gasoline/Diesel – Moderately effective, but dangerous and toxic. In some cases, it is unlawful and can carry a fine for use. Not in the organic tool box!
- Boiling Water – Marginally effective, however it is dangerous to you, to your pets, and harmful to the landscape since it will kill adjoining plants and turf.
- Grits/Cornmeal – Ineffective.
- DE – In theory, this should be effective, but the foraging and feeding habits of Fire Ants do not support it in practice. There is nothing to attract the ants to the product, they can easily avoid contact with it, and they do not feed it to the queen. If the queen cannot be destroyed, the mound will survive.
- Boric Acid – This could be effective, but most people mix it with sugar thinking it will attract the ants to feed and ingest the chemical. Since Fire Ants are not sugar eaters, this is not an effective attractant. I have not experimented with boric acid in a grease bait to see if it is effective. Boric Acid baits are known to take time to work even on sugar attracted ant species. The bait would need to be protected from weather to remain available long enough to be effective.