Fire ants have been observed creating large rafts out of their collective bodies to survive rising flood waters after major storms. This fascinating behavior allows entire colonies to float to safety, but also raises concerns about these invasive pests spreading to new areas.
Raft Formation Captured on Video
Researchers from Texas A&M University managed to capture stunning footage of fire ants assembling into a giant raft structure as flooding inundated their mound. Within an hour, over 100,000 ants had congregated into a loose ball and began linking their limbs together to form a waterproof mass that kept the queen and larvae dry.
“It was both incredible and terrifying to witness,” said lead scientist Dr. Ho Nguyen. “The speed and coordination with which they self-assembled was like nothing I’ve ever seen.” Timelapse photography revealed the ants quickly weaving their bodies into a buoyant, basketball-sized raft structure able to float for weeks until flood waters resided.
Table 1: Fire Ant Raft Properties
|Can reach diameter of 30 cm,
containing 100,000+ ants
|Floats on water due to
|Ants interlock limbs
and bite together
|Can survive afloat
Colonies Use Rafts to Seek New Territory
Experts believe that fire ants intentionally use rafts not just to flee rising waters, but also to spread to new habitats. “By floating downstream, they can traverse far greater distances than they ever could by crawling,” explained ant biologist Linda Schmidt. “It’s a very efficient dispersal mechanism.”
Schmidt’s analysis of flood patterns and ant population spread point to rafting as a key means by which invasive fire ants have expanded dramatically in range over recent decades since arriving in the U.S. “Any major flooding event allows them to leapfrog ahead and infest new regions,” she said. “This is very concerning when it comes to containing their ecological impact.”
Already estimated to cause over $6 billion per year in damage control costs and agricultural losses, fire ants could become an even costlier environmental hazard if flooding events increase as climate change models predict.
Officials Warn of Increasing Fire Ant Raft Sightings
The U.S. Department of Agriculture issued an advisory in the aftermath of last month’s record storms, warning local authorities along waterways to be vigilent for fire ant rafts. Sightings have spiked, and the USDA recommends safely extracting and burning any rafts before they can disperse ants.
“Don’t attempt removal without proper protective clothing – the ants will vigorously defend their colony if disturbed,” the USDA warning stated. Safety gear includes thick rubber gloves and shoes. After extraction, enclosed burning is the recommended disposal method.
“It’s imperative we limit further spread of these rafts,” said agricultural secretary Linda Ortega in a press briefing. “Increased flooding could exponentially increase fire ants’ habitat range in coming years if we don’t remain dilgent about control measures.”
Ortega also requested an additional $4 billion in funding from Congress to expand fire ant monitoring and extermination efforts by the USDA next year. Critics called the amount extreme, but Ortega defended the request, citing the billions already spent battling invasive ant species. “This is an investment in preventing much larger costs down the line as climate change compounds this threat.”
Next Steps: Expanding Biological Controls
While labor-intensive extermination efforts have slowed fire ants’ spread, most experts believe biological controls will be needed to fully contain the species.
“It’s impossible to permanently eliminate ants from an ecosystem,” said Myrmecological Society president Leslie Hubers. “Self-sustaining natural checks and balances are the only viable long-term solution.”
Promising research is underway harnessing special phorid flies as fire ant predators. The tiny flies inject ants with eggs that hatch inside their bodies and devour tissue, killing the ant in days.
“These tiny flies are the fire ants’ worst nightmare,” said Hubers. The flies specifically target invasive fire ants over native species. Huge quantities are being bred in labs for staged release at fire ant hot zones along waterways and other prime habitat.
Several billion flies may be unleashed annually in coming years if trials succeed. Scientists hope phorid fly assaults will help check fire ant expansion and even drive back their range.
“This is the best hope we’ve got,” Hubers said. Combined with traditional physical controls like drowning and burning rafts, accelerated biocontrol efforts could finally turn the tide.
The outcome has sweeping economic and ecological importance across the southern U.S. As climate change drives more extreme flooding, the time to act is now to develop sustainable containment measures before fire ant rafts exploit weather shifts to become an even worse scourge.
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