Which of the following is a method used for monitoring pest populations?

Monitoring pest populations is crucial in pest management, and sticky traps are one of the effective methods used for this purpose. Sticky traps work by capturing insects as they move around, allowing pest control professionals to assess the presence and abundance of various pests over time. This method provides valuable data on pest species, population density, and patterns of activity, which can inform treatment decisions and strategies.

Visual inspections, while useful, are generally not as quantitative as sticky traps, as they rely on the observer's ability to spot pests. Insecticides are primarily used for control rather than monitoring, and traps with bait focus on capturing specific pests to reduce their numbers rather than providing ongoing population assessments. Therefore, sticky traps distinctly stand out as a method focused on monitoring by providing an ongoing record of pest activity.