High Quality Content by WIKIPEDIA articles! The yellow crazy ant (Anoplolepis gracilipes) is a species of ant, introduced accidentally to northern Australia and Christmas Island in the Indian Ocean, and is a pest in both locations. They are colloquially called "crazy" because of their erratic movements when disturbed, and are one of the largest invasive ants species in the world. Along with the red imported fire ant (Solenopsis invicta), the big-headed ant (Pheidole megacephala), the little fire ant (Wasmannia auropunctata), and the Argentine ant (Linepithema humile), the yellow crazy ant is one of the five species of tramp ants, known for invasive behavior and devastating ecological effects. Also known as the long-legged or Maldive ant, it has also been listed among the 100 most devastating invaders of the world. It has invaded ecosystems from Hawaii to Seychelles, and formed supercolonies on Christmas Island in the Indian Ocean.