What is the difference between 'exclusion' and 'barrier' methods in IPM for pests around structures?

• A. Exclusion prevents pests from entering; barrier creates a chemical or physical obstacle to movement.
• B. Exclusion prevents pests from entering; barrier creates a chemical or physical obstacle to movement.
• C. They are the same concept.
• D. Exclusion is only for outdoor structures.

Answer: (B)

Exclusion blocks pests from entering a structure by sealing openings, screening vents, and installing door sweeps or weatherstripping to remove routes of entry. A barrier, on the other hand, is a defensive line around the exterior that pests must cross to reach the interior; it can be physical (mesh, grates, caulked joints, gravel) or chemical (perimeter residual treatments) and is designed to deter or stop movement. In IPM, exclusion reduces the chance pests ever get inside, while a barrier slows or prevents them from reaching the interior by creating an obstacle they must overcome. For example, sealing cracks to keep insects out illustrates exclusion; applying a treated barrier around the foundation to hinder termites from approaching the structure illustrates a barrier.