Wednesday, 25 January 2012

Invasive Red Fire Ants in the USA

Introduced Red Fire Ants – Relentless Invaders

Did you know that the southern parts of the United States are being invaded by a relentless enemy? This diminutive foe started arriving from South America during the 1930s and has left a trail of destruction wherever they have colonised ever since, and now they also seem to be moving on towards world domination. This successful invader is the red fire ant, and fear of this small insect is leaving some parks, gardens and camping grounds in affected areas of the US unused and empty. The red fire ant arrived in the United States by hitching a lift in ships ballast, and so is an accidental invasive species, unlike some introduced species, such as the cane toad in Australia, that were deliberately released in a country for a purpose such as pest control. The introduced red fire ant has also already caused millions of dollars of damage to crops, property and vital infrastructure, and are proving very difficult to eradicate.

Queen Red Fire Ant


What Are Red Fire Ants?

Red fire ants, or Solenopsis invicta, are native to Brazil in South America. The southern US does have its own two native species of fire ant, the southern fire ant and the fire ant, but it is the introduced fire ants that are causing most of the damage and environmental problems. There is another invasive species of fire ant, the black fire ant, which is only as yet only found in Alabama and northern Mississippi, but some experts believe that they could be just the same species as the red fire ant as they are so similar. Introduced fire ants live in colonies, and they build large above-ground nests which can have extensive networks of interconnected underground galleries. The red fire ants build these nest mounds in sunny spots in gardens, parks and fields, and they are rarely to be found in shady areas or dense forest. One of the reasons that introduced red fire ants can grow in numbers so rapidly is that the ants build their nests so that they can control the temperature and humidity inside them.  This means that the ants can keep the temperature in the nest high enough to keep on reproducing, even during the colder weather of the winter season. This rapid expansion of the red fire ant population has seen them spread like wildfire through suitable habitat across the south eastern United States and into western Texas.

What Damage Do Introduced Red Fire Ants Cause?

Red fire ants are very destructive and are costing the US millions of dollars in damage repair. They cause real problems for farmers, as their nest mounds can make ploughing fields and sowing crops very difficult. The red fire ants also feed directly on crops such as strawberries, potatoes, okra, corn and soybeans and their presence can also protect some other insect pest species. However, on a more positive note, they feed on some other pests such as cockroaches, ticks, boll weevils and sugarcane borers.  The lone star tick is regarded as a major livestock pest by farmers, and the red fire ant has been credited with significantly reducing its range. Red fire ants are also bad news for citrus fruit trees, as they chew on the bark and damage it and also feed on the fruit and the growing tips. Red fire ants also cause major problems and damage in homes and commercial properties. The introduced fire ants can get into homes and build nests in wall cavities, under flooring and carpets and around the plumbing. One of the strangest things about the red fire ants is that they seem to be attracted to electrical fields, and so they swarm into electrical appliances, chewing wires and causing damage. The especial love of red fire ants is microwave ovens, and they even seem to be able to survive the high temperatures when the appliances are switched on. They also get into outdoor electrical equipment, sometimes with the potential to cause dangerous accidents, as they can infest traffic signal control boxes or electric metres on properties. Scarily, they have even been found in the lights on airport runways. Even major infrastructure can be destroyed by these ants, as sections of road have collapsed due to the red fire ants removing soil from under the asphalt to build their nests.

Red Fire Ant Distribution Map USA


So Why Are People So Scared of Red Fire Ants?

An individual red fire ant sting is not that painful, and is probably not even as painful as the sting of a wasp or a bee.  They sting like a wasp, by injecting a stinger into your skin, and the red fire ant’s sting initially causes a burning feeling.  This burning sensation gives way to small, itching pustules on the skin. Sometimes these pustules can become infected if they are broken, which can cause scars that take a few months to fade. In some severe cases, there are people who have had to undergo skin grafts or even have had limbs amputated. As with most insect stings, there are also people who are allergic to red fire ant stings, and require immediate hospitalisation for treatment. What causes the great fear of the red fire ants is that most people are not usually only stung the one time. Red fire ants are very aggressive defenders of their nests and territories and will rush to attack any perceived threat. This could be you, one of your children or a family pet, and the ants will swarm over you, stinging you multiple times. It is not just the huge number of ants that is the problem, but the fact that each individual red fire ant has the capability of stinging you several times over. In an area heavily infested with red fire ants it is very difficult to avoid stepping on a nest and disturbing it, as they can quite difficult to spot. Camping in an infested area can also be a nightmare as it is very difficult to avoid being stung, and even leaning on your own garden fence can cause the red fire ants to swarm over you in defence of their territory. Unfortunately, there have even been some people killed by the effects of multiple fire ant stings and the scary reputation of these invaders has also been enhanced by some gory urban myths and scare stories.





Red Fire Ants Go For World Domination

Once colonies of red fire ants are established in an area they are very difficult and expensive to eradicate, and methods range from pouring boiling water into nests, mechanically digging them out and using chemical pesticides. Like a lot of introduced species, the red fire ants are short on natural predators, and in killing the fire ants there is always the risk of also destroying native species. However, red fire ants have now managed to establish themselves in several other countries around the globe, and seem to be bidding for world domination. There are now populations of invasive red fire ants in Taiwan, China, Australia, New Zealand and the Caribbean, and recently genetic experts have discovered that these invasions probably emanated from the US. The ants probably reached these other countries as stowaways in the cargo holds of ships, where they can survive for long periods of time. One of their survival techniques is that if their nest is flooded, they grab the juvenile red fire ants and grip on to each other to form a floating raft of live ants.  If the fire ants become too hungry, they will snack on the youngsters they are carrying to survive.  It has also been suggested by scientists that during the years that the red fire ants have been invading the southern states of the US, that the species has become hardier and have adapted to become even more invasive and aggressive.



The red fire ant has cost the United Stated millions of pounds in damage and destruction of crops, and a wealth of pain and fear for people, livestock and family pets.  There are also many recreational areas that are no longer being enjoyed because of the presence of red fire ants. But can anything be done to halt the march of this little red invader?  Or will the rest of the world soon have to learn to live with huge ant nest mounds on their lawns, stinging ants in their microwaves and extensive damage to their valuable crops and property.





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