Fire ants might come in different flavors, but they’re all basically nasty and unwanted in North Carolina.
Even so, the invasive ant native to South America is here to stay − and is adapting.
Here’s a look at the three species of fire ants found in the Tar Heel State.
Red imported fire ant (Solenopsis invicta)
These smallish insects first hitched a ride to Alabama in the early 20th century, and the ant has quickly spread throughout the South since then. The most common fire ant species, the red invaders are a mix of lots of worker ants and one or several queens per colony. Workers only live a few months at most, while a queen ant − which can lay up to 2,000 eggs per day − may live several years.
Red fire ants are aggressive, especially if their nests are disturbed. A fire ant colony, which consists of several nests, can contain up to 500,000 ants. They also are opportunistic foragers, more than willing to take human food garbage and other insects back to their nests for food.
The ants, which can bite and sting, can be more than a pest to humans and animals, with some people susceptible to anaphylactic shock if stung many times by swarming ants. Some biologists also worry the invasive is reducing the region’s population of ground-dwelling rodents and birds, although surveys often lag by years or decades after the ants colonize new areas.
One of the most common ways the red fire ants spread is through accidental transportation by humans, especially in plant material or soil that’s moved from one location to another. The ants also can hitch a ride on construction equipment as it moves from site to site. The pests also are notorious for forming literally “ant rafts” around their queen during flooding events and floating to dry land often miles away from their original homes, allowing them to quickly recover and spread to new areas.
Black fire ants (Solenopsis richteri)
Black fire ants are much less common in North Carolina, and are actually the nicer of the two species. One of the easiest ways to identify this species from their red brothers is by their distinctive black or dark-brown color. Black fire ants also have a yellow spot toward the end of the abdomen.
Black fire ants actually beat the red ants to the U.S. by a few decades and are well established in some Southern states, including parts of North Carolina.
But they aren’t quite as aggressive as their red cousins when disturbed. This has led them largely to be outcompeted by red fire ants when the two are found in the same vicinity. But they do seem to handle colder temperatures better than red fire ants, which often means they are the first invaders to enter new territory, the foot soldiers and scouts of the fire ant world, if you will.
Hybrid fire ants
Where black and fire ants are both found, the ants have begun to hybridize.
Adapting the best traits of both species, researchers have found the resulting Franken-species of fire ants to be more cold-tolerant than either red or black fire ants are on their own. That, in turn, has allowed fire ants to march into parts of southern Virginia and Western N.C. that officials had originally thought might be too cold for them − although a warming climate and milder winters might be helping them colonize more northerly areas, too.
They also are quite aggressive, likely a trait taken from the red ants.
Reporter Gareth McGrath can be reached at GMcGrath@Gannett.com or @GarethMcGrathSN on X/Twitter. This story was produced with financial support from the Green South Foundation and the Prentice Foundation. The USA TODAY Network maintains full editorial control of the work.
