Fire Ants are here to stay. We can treat them, we can pour boiling water on them, we can do any number of treatments, but what you are really trying to do is minimize them and their impact on your property.
Fire Ants build mounds that are often undetected until a heavy rain. The rain causes flooding in the nest and fire ants will come out to seek food and get away from the wet conditions. Fire Ants prefer to build their nests near sidewalks, driveways and other areas where soil temperature tend to be higher.
Research at Texas A&M University suggests that drenching mounds with a large volume (>2 gal) of hot water (>90°F) or severe mechanical disruption can significantly reduce fire ant activity, however, satellite mounds can form within a few feet of the original mound within a few days. These methods can have useful, but temporary impact on fire ant colonies in areas where a chemical application is not possible.
Home remedies such as applying instant grits, molasses, aspartame or club soda to ant mounds do not work. Pouring chlorine, ammonia, gasoline or diesel fuel on mounds can contaminate the soil and groundwater and is dangerous.
There are a number of beneficial organisms in the turfgrass environment that can have an impact on fire ant populations if environmental conditions are conducive. Microorganisms such as microsporidia can infect immature and adult fire ants, causing shorter life spans and, ultimately, colony decline over several months. The insect-parasitic fungus Beauveria bassiana, toxic to white grubs and chinch bugs, produces spores that attach to ant exoskeleton, germinate and grow inside and outside the ant. However, B. bassiana is much more effective when it comes in direct contact with individual ants rather than applied to the soil surface.
Phorid flies are small, hump-backed flies that can parasitize adult fire ants. Adult flies hover above ant mounds, waiting to come in contact with a foraging worker ant. Once
this occurs, females will lay an egg in the ant behind the head. When the egg hatches, the larva feeds inside the ant for approximately three weeks before the ant’s head detaches from its body and dies. Although phorid flies only decrease the colony population by less than 3%, fire ant workers escape to the underground when phorid flies are detected and are less likely to forage and build mounds.
Chemical applications are most effective when fire ants become active in late spring and early fall when air temperatures are between 70-95°F. Make sure to confirm fire ants are actively foraging prior to application by placing a potato chip or a slice of hot dog on the turf surface near the mound and allow it to sit for 5-10 minutes. There are two basic approaches to chemical control of fire ants. An insecticide can be applied to individual mounds (drench, bait) or it can be broadcast (granules, bait) over a larger area infested with fire ant colonies. Regardless of the method used, the objective is to kill not only the workers but also the queen, because she is the only ant in the colony that is capable of laying eggs.
Individual Mound Treatment: Individual mound treatments typically use less insecticide and are therefore less likely to have an impact on beneficial insects. Because you are treating each mound separately, it is often more time-consuming compared to placing bait stations or using a broadcast application. Be aware that when you treat individual mounds, it is possible that satellite mounds may appear within a few days around the original mound.
— Fast-acting, best applied in high traffic areas or turfgrass stands where there is a low tolerance for fire ant activity.
— Must apply with considerable volume (2 gal water/mound) of liquid to reach the queen in the nest or the colony will survive.
— Best to treat in mid-morning when ants are closest to the surface.
— Do not physically disturb the mound before or after application.
— Apply powder/granules to top of the mound, follow with irrigation.
— Significant post-application irrigation required for active ingredient to reach the queen.
— Slow-acting compared to mound drenches. Depending on active ingredient, products work in about 3-14 days.
— Do not place on top of mound. Foraging ants exit the nest along the outside base of the mound. Place product within a 2 ft radius around mound.
— Baits function as attractants to fire ants, so the product must be fresh (1-3 month shelf life). Keep the product dry (no rainfall, do not apply to wet grass) and do not store near products where it will absorb odors.
— Some products are not labeled for edible plants so make sure to read the label before placing near home vegetable gardens.
Broadcast Application: Broadcast treatments can either be applied as a contact insecticide (granule or liquid) or as a broadcast bait.
— Granules applied to landscape in spreader and watered-in or as a spray application.
— Can choose between slow-acting/long-lasting (fipronil) with only one treatment permitted a year or a fast-acting contact insecticide (pyrethroid). Fast-acting insecticides typically only control ants on the surface but does not eliminate colonies nesting deeper in the soil.
— Baits function as attractants to fire ants, so the product must be fresh. Keep the product dry (no rainfall for 24 hours following application, do not apply to wet grass) and do not store near products where it will absorb odors.
— Products that combine fast and slow-acting ingredients (Extinguish Plus®, Amdro® Firestrike) may work better because they provide quick fire ant suppression but have a longer duration of control.
Regardless of method or product, always follow the label directions when applying any fire ant insecticide.
Foraging fire ants on hot dog slice.
B. Royals, NC State University
Source : NCSU, Entomology and Plant Pathology Department, Terri Billeisen Author. 2018.
For more information or if you have specific questions about plants in the landscape, garden or trees contact Shannon Newton, by email at [email protected] or by phone at 910-875-3461 in Hoke County or 910-277-2422 in Scotland County.
Shannon Newton is an area horticulture extension agent for Scotland County.