Ask how they treat the exterior, how they handle each specific pest, and what happens after the first visit. The answers separate a real plan from a one-time spray.
Start with the exterior and the specifics
A pest problem in Napa usually starts outside, at the perimeter, the eaves, the crawl space, and the roofline, not at the baseboard where you notice it. Homes here range from historic downtown houses to newer stucco homes and vineyard-edge properties, and the pests, Argentine ants, harvest yellowjackets, roof rats, spiders, come in from the yard, the vines, and the land around the house. So the most useful question you can ask a company is how they treat the exterior: the slab edge, the weep screed, the eaves, the crawl space, and the roofline, and what they do about the entry points.
A company that only wants to spray inside, or that quotes a flat price over the phone without asking about your foundation, your setting, and the specific pest, is selling a one-time spray, not a plan. In this climate and this mix of old and new homes, that spray disappoints by the next hot week or the next harvest.
Ask how they treat your specific pest
Different pests need different methods, and the answers should be concrete. Argentine ants: non-repellent colony baiting plus an exterior barrier, not a repellent spray that splits the colony. Harvest yellowjackets: direct nest treatment and removal, not knocking the nest down. Roof rats: roofline and crawl-space exclusion and vine trimming plus trapping, not scattered poison. Subterranean versus drywood termites: an inspection first, then soil treatment or wood treatment to match, which matters a lot in Napa's older homes. German roaches: gel bait and a growth regulator, not a fogger.
A company that describes the same treatment for every pest hasn't thought about yours. The specifics tell you whether they actually understand the local pests and how they behave in wine country.
Ask what happens after the first visit
Most pest work here isn't one visit. The season is long, Argentine ants and rodents re-invade, and yellowjackets, mosquitoes, and ticks are seasonal. Ask how follow-up is scheduled, what triggers a return, and how they confirm a problem actually stopped rather than just slowed. For rodents, ask whether sealing the roofline and crawl-space entry points is included or an add-on, because trapping without sealing is a subscription rather than a solution. For bed bugs and termites, ask about the second visit or the inspection that confirms the result.
The strongest signal is a company that treats the property as a system and comes back to verify, rather than one that shows up once, sprays, and hopes.
Get the details, and be specific
Understand what's included, how recurring service is billed, and what you need to do before a visit. Ask about re-entry times if you have kids or pets. If you own a rental, a tasting room, or a small business downtown or in the vineyards, ask what service records you receive.
Then help the pro help you. Describe exactly what you're seeing, where, and when, whether the ants are in the kitchen or the yard, whether you hear scratching in the attic at night, whether the wasps are swarming the fruit, whether you found pellets under a windowsill. The more specific you are, the faster an experienced local exterminator can tell you what you're dealing with and what it takes to fix it.
Call and describe what you're seeing. We'll match you with a Napa-area provider.