Using plastic, wood, old T-shirts, or duct tape to plug holes is usually a waste of time. Seeing active rats during the day generally indicates a high population of rats in the area. If you hear gnawing, clawing, climbing in walls and ceilings, squeaks, and fighting noises, you may have rats. If your cat or dog excitedly probes an area of floor or wall, you may have rats. If you have rats, trapping is recommended.
Rats are very suspicious of new things.
Try putting unset, baited traps out for a few days. This allows the rats to become accustomed to the trap and the rat trapper to experiment with which kind of bait works best. Peanut butter, cracked pecans, dried fruit, or dried vanilla pudding mix make good bait. Because rats are extremely nearsighted, they use their whiskers and fur as sensors. Rats travel along walls and avoid open spaces as much as possible.