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During winter break, some adventurous students at the University of Maryland participated in a course that took them on a remarkable adventure to the rainforest in Belize to study Mayan culture and the fascinating creatures and plants in tropical ecosystems. By some strange coincidence, Bug of the Week happened to stow away on this tropical odyssey. Last week we met Belizean scorpions in "Belizean sting". This week we visit another denizen of the rainforest, army ants. Back in the day, I was scared silly by the classic 1954 horror movie, "The Naked Jungle" starring Charlton Heston. This was a story of cocoa growers trying to save themselves and their plantation from an apocalyptic legion of army ants. Fearing retribution, I put away my "ant - roasting" magnifying glass for good. Army ants are among the most prominent and important species found in tropical ecosystems. Single colonies of army ants contain hundreds of thousands to more than a million workers capable of capturing and eating thousands of assorted arthropods each day. While hiking in the Mayan mountains, we encountered a column of furious army ants crossing a road. The column consisted of thousands of large and small workers busily transporting food to a temporary food cache or colony site called a bivouac. In lesser numbers within the column were imposing soldiers. These grotesque giants sported huge, sickle-shaped jaws used to defend the workers and colony from attack. The jaws of the soldiers are so large and highly modified for grappling and pinching that they are of little use for eating. In a reenactment of a scene in Mel Gibson's "Apocalypto", I tested the ability of a soldier's jaws to act as a wound suture au natural. They worked just fine. At the raiding end of the ant column, a chaotic melee of murder and mayhem ensues as swarms of stinging and biting workers capture and subdue insects, spiders, and other unfortunate small animals that fail to escape the approaching horde. As army ants move through the forest, an array of flying, jumping, and crawling insects scramble to avoid the onslaught. These in turn attract several species of "ant birds" that take advantage of the bounty, insects flushed from their hiding places by the army ants. After subduing victims, the workers dismember their prey and transport them in large and small pieces back to the food cache or bivouac to feed the larval ants, their attendants, and the hungry queen. The bivouac is usually in a protected location beneath a log or between the buttress roots of a large fig tree. It is formed by thousands of ants linked leg to leg in a protective living cover for the queen and the young. However, army ants may set up bivouacs in man-made structures such as outdoor privies. This can provide an unexpected surprise during a nocturnal trip to the outhouse. During the nomadic phase of the colony, as night approaches the workers stop carrying food toward the bivouac. Instead, workers become highly excited and begin transporting food and ant larvae away from the bivouac along one of the outward leading trails. As the old bivouac disintegrates, the queen and her entourage follow a chemical trail through the forest and establish a new bivouac at a different location. The regular relocation of the bivouac in this nomadic phase enables legions of workers to pillage untapped areas of the forest each day. Several times each the year, the colony enters a statary or sedentary phase. During this phase, the colony hunkers down in one location for several weeks and the queen lays as many as 30,000 eggs each day. Over the span of a few weeks, thousands of eggs hatch and hungry young larvae place enormous demands for food on the colony. By now, larvae produced during the previous statary phase have completed development and matured into new workers. With thousands of new workers to forage and the demand for food high, the colony resumes its nomadic phase and it's time for many small insects to escape or die.

The wonderful book "The Insect Societies" by E.O. Wilson was used as a reference for this bug of the Week. For more information on army ants, please visit the following web sites.

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