Floating fire ant islands

South Carolina has been flooded following one severe rain storm after another during the past week.  Tens of thousands evacuated, 17 dead and about 15 dams have failed. Now, with water everywhere, colonies of fire ants (Solenopsis invicta) can be seen floating on islands of their own making.  "Scientists say the ants trap small amounts of air against their bodies while linked up, making the cluster buoyant enough to float" and are the only ant species able to make rafts. They are a well-known invasive species from South America, also known as RIFA (red imported fire ant) and are found in the southern states of the USA, in the southwest and sporadically in a few other states.  "In other countries, they have been found in northern Mexico along the Rio Grande River, eastern Australia including Brisbane, and several locations in Taiwan and mainland China. They have been detected several times in New Zealand but have been eliminated." Source  
 


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The briefest contact with one of these rafts can make them swarm vertically and result in very painful bites, which are easily infected and leave permanent scars. Each ant can bite 7-8 times.

              
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It is believed this species arrived in their current locations via packing crates from South America beginning about 1918. Expansion in the USA, first in Mobile, Alabama:

 
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S. Carolina floods.kmz (824 B)
         

Hardy little girls, aren't they? To be technical, like bees and wasps they can bite, but the mouth is simply used to hang on while the sting delivers multiple injections. The red harvester ants in my part of the country also use this technique, but even a large colony does not begin to compare to a fire ant colony.

Clever! Leverage always helps. I saw some truly terrifying photos of when things go very wrong after a mass of bites. I mean, stings. Thought it best not to post those!