That scratching in the attic is usually a roof rat, and in Napa the vineyards and creeks are how it gets there. Trapping without cutting off the route is a losing game.
The rat that lives up high
The rat that matters most in Napa isn't the burrowing Norway rat of city alleys, it's the roof rat, an agile climber that prefers to travel and nest above the ground. Roof rats are the dominant rat across wine country, and a valley wrapped in vineyards, creek corridors, and oak woodland is close to ideal habitat for them. Vine rows and trellis wires, overhanging limbs that touch the roof, fruit and nut trees, ivy and dense shrubs against the house, and utility lines running to the eaves all give a roof rat a route from the land to your roof.
Once on the roof, they get into the attic through gable vents, gaps where the roof meets the eaves, and roofline penetrations, then nest in the insulation and come down into wall voids, garages, and crawl spaces at night. The scratching and scampering you hear overhead after dark is the giveaway.
Why the vineyards make it worse
A home surrounded by or backing onto vineyards has two things a roof rat wants: a food supply and a travel network. Dropped and ripening fruit feeds them, and the endless rows of trellis wire act like an aerial highway that leads right up to the buildings and the trees against them. The creek corridors and oak-covered hills that ring the valley add cover and more rats.
That's why trapping alone rarely holds near vines and open land. You can clear the attic this month, but if the trellis wires, limbs, and fence lines still lead to the roof, new rats simply follow the same route in. The route is the real problem, and in Napa the route is the land around the house.
Trapping plus exclusion, not poison
Scattered rat poison is a poor choice in a home with a roofline rodent problem. A poisoned roof rat usually dies in the attic or a wall void, and the odor lasts for weeks in a spot you can't reach, and the bait itself puts poison where pets, children, and the local wildlife, including the hawks and owls that hunt rats, can be harmed. Around vineyards especially, keeping poison out of the food chain matters.
The reliable approach is trapping on the runways the rats actually use, combined with exclusion: sealing and screening the gable vents, soffit gaps, and roofline penetrations, fitting the garage door, and closing the crawl-space and foundation gaps mice use. Do the trapping and the sealing together and the attic goes quiet for good.
Sealing a home in the vines
Exclusion on a vineyard-edge home is detailed work. A rat can push through a gap the size of a quarter, so every gable and dormer vent needs screening, every roofline and utility penetration needs sealing, the crawl-space vents and access need mesh, and the eaves need a careful check for the small openings that construction and weathering leave. It's the part that turns a one-time trap-out into a lasting result.
Pair the sealing with cutting off the routes, trim the vines, limbs, and ivy back off the roof and walls, pick up dropped fruit, secure pet food and birdseed, and clear garage and crawl-space clutter, and the house stops being an easy target. A local pro does the roofline and crawl-space exclusion, sets the trapping on the active runways, and comes back to confirm the activity has actually stopped rather than just slowed.
Call and describe what you're seeing. We'll match you with a Napa-area provider.