Final answer:
True. After treating a subarea for subterranean termites by trenching and treating, the applicatior must post a sign outside the access opening warning about the health effects of the pesticide use.
Step-by-step explanation:
True. After treating a subarea for subterranean termites by trenching and treating, it is necessary for the applicator to post a sign outside the access opening warning about the health effects of the pesticide use. This is important in order to inform individuals about the potential risks associated with the use of pesticides and to ensure their safety.