Lewis & Short

gĕrŭla, ae, f. [gero], she that bears or carries, Tert. Anim. 19 fin.; id. adv. Jud. 9 med.; App. M. 6, p. 181: navis gerula sacrorum, Sol. 1 fin.
A working bee,
Plin. 11, 10, 10, § 24.