Managing Fire Ants on the Ranch and Farm: Defending Against the Ant Invasion

Fire ants, also known as RIFA (Red Imported Fire Ants), have become a major pest for many southern states and counties. These ants, infamous for their aggressive nature, can cause damage in several different ways to humans, livestock, and equipment. These invading insects cause billions of dollars of damage across the US, affecting multiple industries and residential spaces. On top of that, their prolific and rapid breeding is helping them spread quickly to new areas, as they face less competition here in North America compared to their natural home in South America. Today, we will take a closer look at the red imported fire ant to learn more about it, and what we can do to help contain and manage the pests.

Just looking for fire ant management suggestions? Click the button below!

According to the University of Tennessee’s Extension, imported fire ants come in three different varieties in the states. There are the black imported fire ants, known as Solenopsis richteri, the red imported fire ants, Solenopsis invicta, and then a hybrid fire ant that came from the two invasive ant species combining. While there are native species of fire ants to the Americas, they are often rapidly overshadowed by their more infamous cousins who tend to inflict far more damage.

These invasive species of fire ants tend to use intricately designed mounds above the ground to assist their colony with temperature regulation and keeping the nest warm for the growing brood.  However, just because a large mound is not present does not mean that there are no ants there. In hotter periods, the ants tend to nest and stay further under the earth to escape the hotter temperatures. They will even build tunnels that go all the way to the water table to help cool the nest on hotter days. The water moisture also helps the ants with building, making it easier to stick granules of dirt together.

Most species of ants usually have a single queen and several “princesses” who are new queens that are not quite ready to start a nest yet. These princesses will be sent out in a large group after a mating flight to found their own colonies. The same applies to most imported fire ants. However, some colonies contain multiple queens (called polygyne) that all produce eggs for the same nest.

According to the University of Florida’s researchers, broods that use the multi-queen strategy tend to have a few variations from other fire ant broods.

For example, the multi-queen variety tends to build new mounds closer together and are not aggressive to neighboring colonies, causing a larger number of fire ants per acre. Additionally, the workers tend to be a bit smaller, and one queen from a polygyne colony will not produce as many eggs as the single queen from other fire ant colonies. However, having multiple queens often makes up for the reduced egg production per queen, as these polygyne colonies often produce a overall greater number of eggs.

Fire ants are most well known for their incredibly aggressive nature and painful sting. When a fire ant attacks, it will grip the target with its mandibles, and then proceed to use its rear stinger to jab and inject venom into the victim. While doing this, it will pivot at its head, and continue to jab and insert venom repeatedly, typically up to seven or eight times. The venom injected by the fire ants has a high concentration of toxins which causes the burning sensation associated with fire ant stings (Ferguson College of Agriculture).

Due to their aggressive nature, if anything disturbs their nest, they will attack it relentlessly. Fire ants often wait to begin stinging until additional ants are on the target, resulting in a simultaneous strike, sometimes before the victim is even aware of what is happening. Most fire ant stings are non-lethal, but mass numbers of stings can be fatal for younger livestock and children. Doses of the venom can also cause deadly allergic reactions in some people. Even if the stings do not kill an animal, too many can cause sickness, requiring some form of medical treatment. While most adult animals can usually avoid too much damage, a young calf or fawn born directly into a fire ant nest has a decent chance that the ants will kill it before it can escape.

Fire ants are also known for their strange affinity for electrical fields and damaging equipment. According to this report on managing fire ants that get into electrical equipment, The ants often end up foraging in electric boxes and moving nests into them. When nesting in an electrical box, the ants chew through wires or move soil into the location, causing corrosion. Nests in equipment cause extra problems, as the ants attack any maintenance personnel who attempt to fix the malfunctioning equipment. Additionally, when ants from several different species end up getting shocked, they release communication pheromones that attract other ants to the location. This can result in a large pile of dead electrocuted ants, gumming up and damaging the system.

The ants don’t limit their damaging tendencies to poorly located colonies inside electrical equipment alone. They sometimes build nests in crevices of equipment, which can gum up machinery or lead to a nasty surprise for employees handling the tools. Additionally, fire ant mounds in fields often harden, and, when tall enough, can dull and damage cutting machinery as it hits them (Management of Imported Fire Ants in Cattle Production Systems).

While the damage to creatures and machines can be frustrating, that’s not where the damage stops. Some crops end up getting attacked. as well. According to Karen, Jay, and John in their research about red imported fire ants, fire ants will attempt to devour developing fruits, seeds, roots, or tubers if available. Citrus trees are not safe either, as the ants sometimes feed on the bark and cambium to collect sap if their nests are close enough, which can cause damage to younger trees.

The ants are known to feed on the seeds of several row crops such as wheat, sorghum, corn, cotton, and soybeans. For cotton, even though they occasionally eat the seeds, fire ants can be considered beneficial, as they can devastate budworm and bullworm populations in the field.

Fire ants are infamously aggressive, and this aggression boils over into the way they treat their insect neighbors. Fire ants will attack and compete with native colonies, potentially wiping them out. These ants also forage heavily, killing many insects they come into contact with for food. While this does mean they often reduce the number of pest insects such as ticks and horn flies, they will attack beneficial insects, as well.

Additionally, fire ants are “honeydew” enjoyers, a sweet substance produced through aphids and a few other pest insects. The fire ants will protect them from harm to continue collecting their nectar. This can increase aphid numbers and cause additional damage to crops (Damage to Dry Crop Seed by Red Imported Fire Ant).

While there are several things you can do to help manage fire ants on your property, there are also a few efforts by the USDA and research teams to help deal with imported fire ants. The USDA has a series of rules and regulations implemented to try to help slow down the spread of fire ants, including regulations on the transportation of feed, soil, plants, and more. You can find the current rules and regulations concerning fire ants on the USDA’s site.

One of the potential controls found by researchers is a species called the phorid fly. The University of Texas at Austin has a fire ant project that is devoted to researching and implementing controls using these parasitic flies. While Phorid flies do not completely wipe out a nest like a chemical control, they do help keep the ant population under control. As these flies only target the specific imported fire ant species, it proves to be an effective control method as the native ants won’t be harmed.

These flies find ant forage trails or mounds and hover over the ants below. Picking a target, the fly will zip in, inject an egg into the ant, and take off again before the ant can fully react. The ant remains paralyzed for a moment before trundling off to rejoin the rest of the colony. The egg quickly hatches into a hungry larva that will eventually move into the head of the ant, killing and decapitating it to begin its pupa stage.

While the number of ants killed in this manner is below five percent, it does cause the ants to attempt to avoid the flies by hiding, retreating to the nest, and other odd behaviors. This distraction and harassment campaign can slow down the colony’s progress, and help other native ants take advantage of the distraction. There is also a possibility that the phorid fly can transmit diseases between different colonies of fire ants, though this is still being researched.

Phorid flies are not the only avenue of biological control methods that researchers have been studying. Research into nematodes, fungus, bacteria, and parasitic species are all additional methods being investigated. Several fungi types have proven effective in some scenarios. These fungi can cause a host of problems for the ants, including reducing foraging activity, killing larvae and workers, and even damaging exposed queens.

Beneficial nematodes have been a controversial option for biological control, as well. While the parasite is quite deadly when it catches up to a fire ant, research suggests that the fire ants are typically fast enough to escape when they realize something is wrong, and end up simply moving the colony elsewhere to avoid them. This ends up just moving the problem, and in some cases, they may return to the original problem area once the nematodes have died off.

One virus that seems to be effective against RIFA, is Solenopsis invicta virus 3. This virus tends to reduce the survival chance of infected ants and lowers the speed at which they can reproduce. Another danger for the fire ants is a microsporidium called Kneallhazia solenopsae. It works by slowly killing off the colony through spores it creates that harm ants that eat them. These spores cause infected queens to lay far fewer eggs, and die prematurely (Dampening the Spread of Fire Ants).

Unfortunately, many of these potential control options have run into roadblocks or proven ineffective when introduced to fire ants in the field. A major issue that is always confronted with each biological control method is making sure that these diseases and parasites designed for use against fire ants do not adapt to other species in the area, as well. These issues can make progress with biological control methods much slower than expected.

The Fire Ant Pest Control Extension has created an information page with advice for controlling fire ant problems in different locations and scenarios. If your experiencing a fire ant infestation, this may be helpful to your management strategies.

The USDA has information in regards to its quarantines and regulations for the Red Imported Fire Ant located on its site. Use the interactive map to see if your counties fall into one of the quarantine zones, and then read through the regulations to see how it may affect you and your operation.