Size no problem for invasive ants

The red imported fire ant (Solenopsis invicta) has been steadily marching through the U.S. since it was introduced to the south around the 1930s or 1940s.  It has become established in most of the southern states and is even found up into Maryland and Virginia.  How have they become so successful in taking over?

red imported fire ant (Solenopsis invicta) by USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org

Part of the reason may be their ingenious excavation techniques.  When presented with large-grained soil, they will grab one piece at a time and move them out of the tunnels.  When encountering finer soil, they with grab and compress multiple grains together and move the compact piece our of the tunnel.  Having techniques in place to address different soil types has allowed them to invade across many substrates.

Source Article: Invasive ants are extreme excavators
More images: red imported fire ant