ns of the average intensity of policing in the colony, which is Z+ wz. where z is the fraction of mutant workers in the colony. We have PIZ +vvz). Ra+P( )wz+! Ribv2z2 +O(w3) r,-.R(Z+wz)= R(21+ ralwz +I R. (Znv2z2 +O(tv3) (11) We have made the substitutions p,-•P(Z+ wz) and rz -.R(Z+wZ). and (11)