Queue Size Determines the Width of Tunnels in the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

We present a model of tunnel excavation by termites that requires no pheromone labeling of soil or work sites, but instead relies on tactile interactions and individuals who actively orient their movement. Potential termite excavators moved from the tunnel origin towards the distal end of the tunnel and formed a queue behind those termites at the digging face. Delayed termites excavated soil laterally from the tunnel wall at a position governed by their position in the queue of termites. By examining excavation under artificially induced conditions of longer and shorter queues of termites at the tunnel end, we showed that tunnel width increased with increased queue size and the rate of lateral excavation in a process we termed “digging pressure.”