Polyergus workers are incapable of caring for brood, for the most part due to their dagger-like, piercing mandibles.
They have lost the instinct for carrying out even rudimentary brood care, and even for feeding themselves (which they are unable to do).
Polyergus 'workers' exist more as a force of improvised soldiers, acting in essence solely to raid the Formica nests.
The captured ants are generally referred to as "slaves" in scientific and popular literature, though recent attempts have been made to apply other human cultural models.
The new workers quickly assimilate the characteristic odor of the mixed-species colony — without violence or coercion.