Meeting Abstract

112.5  Monday, Jan. 7  Assembly and disassembly of fire ant bivouacs MLOT, N.J.*; MORRISON, J.; LEAMY, M.; TOVEY, C.A.; HU, D.L.; Georgia Tech, Atlanta; Georgia Tech, Atlanta; Georgia Tech, Atlanta; Georgia Tech, Atlanta; Georgia Tech, Atlanta njmlot@gmail.com

Fire ants are capable of linking together to form bivouacs, which serve as temporary shelter when alternatives cannot be found. While the presence of army and fire ant bivouacs has long been known, much remains to be learned about the factors that limit the shape and speed of construction. In this combined experimental, theoretical, and computational study, we use time-lapse video to investigate the construction of fire ant bivouacs that are built against a teflon supporting wall. By roughening the wall, we can control the maximum adhesion and shear force applied by the ant’s foot. In turn, we find that the wall properties affect the height and shape of the constructed bivouac. We present a model that rationalizes bivouac shape based on ant adhesion force and the internal distribution of force by the ants. Next, we consider the bivouac disassembly process whereby ants evacuate and disassemble the bivouac and move into a nearby home. We present an agent-based simulation, founded on experimental measurements of ant trajectories, that predicts the rate of disassembly. We pay particular attention to traffic jams and resulting ant clumps that slow the rate of disassembly when ant numbers are sufficiently high.