Anant mill is an observed phenomenon in which a group ofarmy ants, separated from the main foraging party, lose thepheromone track and begin to follow one another, forming a continuously rotating circle. This circle is commonly known as a "death spiral" because the ants might eventually die ofexhaustion. It has been reproduced in laboratories and in ant colony simulations.[1]
The phenomenon is a side effect of theself-organizing structure ofant colonies. Each ant merely follows the ant in front of it, which functions until a slight deviation begins to occur, typically by an environmental trigger, and an ant mill forms.[2] An ant mill was first described in 1921 byWilliam Beebe, who observed a mill 370 m in circumference.[3] It took each ant two and a half hours to make one revolution.[3] Similar phenomena have been noted inprocessionary caterpillars and fish.[4]
