The digging behavior of the red imported fire ant Solenopsis invicta in relation to body size

Workers of various body sizes exist in the red imported fire ant Solenopsis invicta forming a polymorphic caste. In previous studies, larger workers tend to forage more and carry larger objects compared to smaller workers. In addition, larger workers can move large soil particles when creating nests. This study observed the digging behavior of the polymorphic workers to determine if a large body size worker could move a large size bead by digging compared to a small body size worker. In previous observations when picking up small beads, workers only use their mandibles and move forward out of the entrance hole. For larger beads, workers use both their mandibles and forelegs and move backwards out of the entrance hole. Ten colonies were collected from the field and housed in the lab. A random sample of workers were taken from a colony and introduced to various sizes of glass beads. The bead sizes ranged from 0.25 to 2.0 mm. The widths of the heads of workers that picked up beads were measured to determine if body size increases as the bead size increases. This study provides more information about the division of labor in the polymorphic caste of the red imported fire ant.