Final answer:
It is false that trenches treated for subterranean termites do not need to be filled with clean soil if difficult to access; it's crucial to refill trenches to prevent termites from returning.
Step-by-step explanation:
The statement after treating a sub area for subterranean termites by trenching and treating, the applicator does no need to fill the trench with clean soil if the areas are difficult to access, is False. Filling the trench with clean soil after treatment is an essential step to ensure the effectiveness of the treatment and to prevent re-infestation. It doesn't matter if the area is difficult to access; appropriate measures must be taken to access and backfill the trench.
Termites, like subterranean species, can be persistent and resourceful pests, and leaving open trenches can lead to ineffective treatment and provide new pathways for termites to re-enter the area. The goal is to create a barrier that termites cannot penetrate, which means any trenches excavated during the treatment process must be refilled with soil treated with termiticide.