Scientists in Europe have discovered a "supercolony" of ants, stretching thousands of miles from Italy to Spain. Apparently, the ants have lost their ability to recognize family vs. strangers and instead work together in a giant cooperative effort. How did this breakdown of recognition occur? Research points to factors associated with the repeated introduction of these Argentine ants (Linepithema humile) into Europe. You can read the Associated Press' version of the story on ABCNews.com, or if you're feeling adventurous (and have access), you can read the original paper from the Proceedings of the National Academy of Sciences (-Or-, if you're super-patient and don't have access, check back in 6 months and read the article for free.).
This story is getting a lot of press, but the truth is that Argentine ants, regardless of colony size, have become invasive in many parts of the globe, including New Zealand (see link above), Australia, and the U.S., where they threaten horned lizard populations in California.