Natural Highlights: Floating Fire Ants  

At the Wolf River Conservancy, we spend a lot of time talking about and trying to control exotic invasive plants such as privet and callery pear, working with both students and volunteers to manage them.  There’s another exotic invasive species out there that we only warn volunteers about, one that is painfully familiar to most Southerners: fire ants!

Huge amounts of rain this spring have reminded us of a hazard peculiar to flooded conditions in the southeastern states:  floating rafts of fire ants.  Those who have inadvertently made contact with one of these while in the water find themselves quickly covered with aggressively stinging ants – dozens or hundreds of them.  While many ants bite, fire ants and other members of the genus Solenopsis both bite using their mandibles and inject venom with a stinger.  And not just once!  Fire ants will sting repeatedly, inflicting painful, itchy pustules.  Even worse, some victims may suffer a life-threatening allergic reaction.

The Red Fire Ant (Solenopsis invicta) was introduced to the United States from its native range in South America in the 1930’s, apparently via the coastal shipping industry. It has since moved across the southeast, acquiring its own acronym – RIFA, for red imported fire ant - as its reputation grew.  Fire ants are an especially destructive and intractable invasive pest, nearly impossible to eradicate, which inflict serious harm on native species and their ecosystems.  Typically, the red fire ant can be recognized by its red body and black/brown rear (the gaster), but there’s no need to get so close.  Just look for large mounds of freshly dug earth in open, disturbed areas, often near water.  If you accidentally step on a mound or kick it on purpose, you may regret it; an army of angry, formidable ants will rush to the attack.

In their native South American habitats, fire ants aren’t especially numerous or problematic, held in check by the many competitors and predators with which they coevolved.  But as an exotic invasive species, they overwhelm native ant species, and present a grave threat to amphibians, reptiles, ground-nesting birds, and other species they might encounter, resulting in a loss of ecological integrity.  As for managing fire ants, even if one treatment is effective at destroying a colony, fire ant queens from surrounding areas can quickly replace it.  The worst invasive species, whether fungus, plant, or animal, tend to be, like the fire ant, very resilient and difficult to manage.

There are over 12,000 known ant species in the world, and scientists estimate that there are thousands more yet to be discovered.  Members of the Hymenoptera, the same order as bees and wasps, ants have a remarkable diversity of social behaviors, ecological relationships with other plants and animals, foraging and survival strategies.  Red fire ants are no exception; their huge colonies may contain multiple queens and thousands of individuals, they are highly aggressive to both intruders and other ant species, and they can rapidly relocate the colony when necessary, such as when it is inundated by floodwaters.  Using the larvae of the colony as flotation devices, the ants lock their legs tightly together, creating a moveable waterproof island, with some ants paddling to guide the colony to a dry location, others changing places with the ants underwater on the bottom so that all survive.  

Check out some amazing videos of floating fire ants with the following links.  

https://www.youtube.com/watch?v=suV1ePJSniQ

https://www.youtube.com/watch?v=MJ4IjC512bg

https://www.youtube.com/watch?v=cfKr6rnpakE

We’ve also included some useful website information here:  

https://fireant.tamu.edu/learn/history-of-the-red-imported-fire-ant/

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