Fire ants can be a nasty problem in the home landscape. They love to make unsightly mounds in the middle of our lawn turf and flower beds. The loose soil of a freshly turned garden plot is also the perfect environment for a fire ant colony. Besides being unsightly, fire ants can be downright dangerous, as some people can be seriously allergic to their stings.
The red imported fire ant was imported from South America in the 1930s, most likely on accident through cargo shipments. With no native predators, their populations have continued to flourish almost unchecked. Fire ants have infested around 260 million acres of land in the US, accounting for about $6 million annually in damage and control costs.
Most hardware stores offer two options for fire ant control: baits and broadcast ant poisons. The broadcast poisons consist of granular clay particles coated with a non-selective insecticide like bifenthrin. Ants are killed when they come in contact with the chemical residues.
Fire ants baits can be a better option. These baits are made of a small piece of corn cob saturated with soybean oil that contains an active ingredient, usually indoxicarb, hydramethylnon, or methoprene. These are acute poisons which kill the fire ants after they consume the bait.
Because soybean oil is used as a chemical carrier, fire ant baits do not store long and are prone to spoilage. Only buy the smallest amount of bait that you need to treat your yard. If you have leftover bait from last year, it may not be very useful this year.
When applying bait around fire ant mounds, it is better to spread the product in a 2-3 foot diameter circle around the mound, rather than directly on top of the mound. Fire ants rarely forage for food directly on their mound, so they will be more likely to pick up the bait if it is away from their mound.
Fire ant baits are best applied on warm sunny days in spring and fall. Wait until the afternoon to allow for morning dews to dry off. Baits should never be put out on wet soil or watered in. This will change the taste of the baits, causing them to be less effective.
Avoid disturbing the mounds before and during bait treatment. Kicking the mound will cause the colony to emit alarm hormones. The fire ants will then be more focused on defending the colony rather than foraging for food.
Once applied, fire ant baits should be gone within several hours as the ants begin to forage. You should see a reduction in the colony in a week to ten days. If the mound is still very active after this time frame, a second bait treatment may be needed.