In IPM for roof rats, which principle is emphasized?

• A. Get some outdoor cats
• B. Exclusion
• C. Installing toilet paper on all the trees in the area. It freaks out the rats and the residents
• D. Close all ground burrows

Answer: (B)

Prevention through exclusion is emphasized in IPM for roof rats. Roof rats are agile climbers and commonly gain access to structures via rooflines, eaves, vents, gaps around pipes, and damaged openings. By blocking these routes—sealing cracks and gaps (typically small openings on the order of a quarter inch or larger), installing vent screens or hardware cloth, securing soffits, repairing damaged roofing and flashing, and keeping access points closed with weatherproof materials—you prevent new rats from entering and establishing shelter inside the building. This reduces infestation pressure and minimizes the need for chemical controls, making it the most effective long-term tactic in an IPM approach. Other options don’t address how roof rats get into structures or are not practical or reliable pest-management methods for this species.