Residual spray can cause colony fragmentation in Pharaoh ants.

• A. Fragment Colony
• B. Inhibit Growth
• C. Eliminate Colony
• D. No Effect

Answer: (A)

Pharaoh ants form colonies that are spread across multiple nests and often have several queens. When a residual spray is applied, it can disrupt pheromone trails, kill or repel a portion of the workers, and create barriers within the nest structure. This disruption can cause the colony to split into separate, independent subcolonies, each with its own nests and potentially queens. That tendency for the colony to break apart rather than be instantly wiped out is what “fragments the colony” captures in this scenario.

So the best description of the effect is that the colony fragments. This isn’t guaranteed elimination, nor a simple, uniform inhibition of growth, and there is a real effect from the spray—fragmentation—rather than no effect at all. In practice, this is one reason residual sprays are often avoided for Pharaoh ants in favor of baits or other methods that minimize triggering fragmentation.