How do I evaluate a pest service for winter prevention?

Ask directly for the NH applicator license number and category before discussing anything else. New Hampshire licenses commercial pesticide applicators by category under RSA 430 and the Pes 100–1100 rules; general household and structural pest work — including winter rodent exclusion — falls under category F1. A legitimate company answers this instantly, because it's a matter of public regulatory record, not a trade secret. A company that answers with reassurance about "certified technicians" instead of a number and category is answering a different, easier question.

Ask whether the visit produces a written inspection report identifying specific entry points, evidence found, and the conditions driving pressure — clutter, food storage, moisture, exterior firewood or vegetation against the foundation. A verbal "looks like you've got some activity" is not documentation; it can't support a warranty claim, an insurance question, or a second opinion. New Hampshire actually requires applicators to keep an application record under Pes 901.02 with seven specific items including product, EPA registration number, and date — asking for a copy of that, plus the inspection findings, costs nothing and gives you something to hold onto.

Ask directly whether the proposed plan includes physically sealing identified entry points, or whether it's recurring pesticide application on a calendar regardless of findings. This is the single most consequential question on the list, because exclusion — sealing gaps with durable materials — is what actually stops rodents from re-entering; a spray schedule alone knocks down the current population and lets the next one back in through the same unclosed hole. EPA's guidance is explicit that pesticides "should not be applied unless the pests are actually present" — a plan built entirely around a recurring spray, with no sealing component, is optimized for repeat visits, not for prevention.