Variation in excavation rate among tunnelers in the Formosan subterranean termite

Division of labor is a common feature of insect societies and has been theorized to account for much of their success. Asymmetries in the work of individuals, whose aggregate labor results in the completion of a task, can lead to the emergence of key individuals that dominate or govern the task. Coptotermes formosanus Shiraki excavate in a series of alternating workers whose efforts combine not only to elongate tunnels, but to guide the direction of propagation. When groups of 100 termites were presented with a single tunnel, only ~ 16% of termites entered. Of those that entered, the level of excavation was not uniform, with 20.6% of termites responsible for over half of the total excavation. These termites, a small percentage of the total available work-force, act as key individuals, producing the majority of labor and possibly guiding the efforts of others. An examination of the excavation patterns of individuals shows that some individuals excavate sporadically, but at a very high rate (number of excavation events per time). By focusing their effort over a short period, these highly active individuals may influence the orientation of a tunnel and the formation of branches to a degree out of proportion to the total amount of digging they engage in.