By competing with rodents for seeds, black ants help control rodent populations that pose a public health risk  However, a very aggressive species of black ant, the Loma ant, which has recently invaded a certain region, has a venomous sting that is often fatal to humans
Ttherefore, the planned introduction into that region of ant flies, which prey on Loma ants, would benefit public health
Ant flies do not attack black ants other than Loma ants.