Bug Week


Fire Ant

Meet the red imported fire ant, also known as RIFA.

Scientifically known as Solenopsis invicta, this invasive insect hails from the central part of South America, where natural enemies and pathogens kept its populations in balance with the local ecosystems.

In the southern United States, it’s been a different story. With no natural enemies, and few barriers except cold temperatures, the ant has spread from the Gulf of Mexico coast all the way to the Atlantic and Pacific coasts.

The exact circumstances of the RIFA’s arrival in the U.S. are uncertain, but it’s believed to have come in via a boat from Brazil that docked at Mobile, Alabama or Pensacola, Florida, sometime between 1933 and 1945.

The RIFA’s rapid geographic expansion came about partly because this bug is a hard worker, and builds underground nests capped by dirt mounds that can measure two feet across.

But the bigger problem humans have with this Bad Bug is its habit of repeatedly stinging anyone and anything that comes close to a nest, even by accident. Serious stinging incidents usually require hospitalization.

Remember how we said the RIFA is a hard worker? The same idea applies when a RIFA colony defends its nest. These bugs are seriously aggressive, and will pile onto any errant foot or paw that lands near the mound.

An average RIFA colony may have 80,000 workers but a really big one might have upwards of a quarter-million workers. Every worker has a stinger and can sting repeatedly.

Oh, and when one worker stings, it releases an airborne chemical called a pheremone, which alerts other workers to start stinging. So fire ant infestations should be taken seriously, especially by parents and pet owners.

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Red Imported Fire Ant – UF/IFAS “Featured Creatures”

UF/IFAS entomologist Dr. Phil Koehler discusses the phorid fly, a possible biological control agent against the RIFA: