ENVIRONMENT

They’re more venomous, more aggressive, and “Holy crap. I have never, in my entire career as an ant researcher, seen *anything* like this.” (The Atlantic)

What are fire ants?

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Discussion Ideas

• Take a look at some of the jaw-dropping photos of fire ant colonies floating in the floodwaters of the Houston area. What are fire ants? Read through this “Geography in the News” article for some help.
  • Red imported fire ants (RIFA) are an invasive species that entered the U.S. about 100 years ago. Fire ants are native to central-western South America, and were accidentally introduced to the port at Mobile, Alabama, with a shipment of cargo from Argentina or Brazil. They have spread throughout the southern U.S., often displacing native species.
  • Fire ants earn their nickname thanks to their painful, venomous sting, a sensation often compared to a burn.
  • Considered pests in the U.S., fire ants are blamed for more than $5 billion in medical and agricultural damage every year.
    • Fire ant stings are rarely fatal, but can easily become infected and require medical attention. Medical treatment is usually limited to topical and oral medications, but can sometimes include emergency care for anaphylactic shock and long-lasting welts.
    • Fire ants are omnivores, and will consume carrion, other insects (they love ticks and crickets), seeds, grains, and fruit. Damage to agriculture includes crop loss, veterinary care, and livestock loss.

• What are the “floating fie ant colonies” menacing Houston?
  • Just what they sound like—hundreds of thousands of ants safely floating on water.
    • An individual ant’s exoskeleton is moderately hydrophobic, but its water resistance and buoyancy are magnified when thousands of ants link themselves together in a “process analogous to the weaving of a waterproof fabric.”
    • Fire ants clump together in mandible-tarsus and tarsus-tarsus connections. (An ant’s mandible is its mouthparts, and its tarsi are the five segments of its legs.) Clumping their leg segments together “allows the ants to change the shape of their structures by bending or stretching their legs. That explains why the structures are so elastic, and why they can absorb incoming forces more effectively.”
    • The rafts are so good at floating “that it’s hard to physically push them down with a stick—try it, and the raft will dent the water but won’t go under.”
    • Rafts can last up to three weeks, but most start to fall apart after a week.
    • The rafts are an adaptation that served ant colonies well in the South American flood plains where they evolved. Watch the video below to see how that works.

• Why are floating fire ant colonies more dangerous than terrestrial ant colonies?
  • Floating fire ants “deliver higher doses of venom because they have 165 percent as much venom inside them as normal fire ants. The flooding [makes] them more aggressive and dangerous.”
  • The colonies can also be well-hidden. “Piles of debris can act like islands, where fire ants have congregated during the flood.”
  • “After Hurricane Katrina, Linda Bui, an entomologist at Louisiana State University, remembers seeing evacuees from New Orleans come into a field hospital with bands of unexplained rashes around their legs and waists after wading through floodwaters. ‘They were like something none of the medical professionals had ever seen,’ she says. ‘I was like, ‘Those are literally fire ant stings on top of fire ant stings.’”

• How do rescue workers, pest control officers, and everyday citizens fight fire ants?
  • wait. The ants will drown if floodwaters persist, as happened after Hurricane Katrina.
  • insecticide. Pest control agents often inject insecticide in fire ant mounds or insert insecticide-treated bait around the mounds.
  • fish, birds, and insects. As seen in the video above, floating fire ant colonies can fall prey to natural predators.
  • soap. In floating colonies, dish soap breaks the surface tension that keeps the colony afloat, and the ants drown. “Dawn is a not a registered insecticide, but it will break up the surface tension and they will sink,” says Bui, the entomologist.

TEACHERS TOOLKIT

The Atlantic: Yes, That’s a Huge Floating Mass of Live Fire Ants in Texas

BBC: Floating fire ants form rafts in Houston floodwaters

Nat Geo: The Architecture of Living Buildings

Nat Geo: Fire Ants, Surviving and Thriving

(extra credit!) PNAS: Fire ants self-assemble into waterproof rafts to survive floods