The short version
Trap the ones inside, then seal the gaps. An inspection usually costs $75–$250.
- Look for droppings, gnaw marks and night-time scratching.
- For Derry homes, mice usually start moving indoors in September and October, as nights get colder.
- Traps remove them; sealing keeps them out.
- Never sweep or vacuum droppings dry.
Anyone in Derry dealing with mice or rats, or hoping to keep them out.
What to look for
Rodents are mostly unseen. You hear them at night and find droppings by morning. A mouse fits through a gap the size of a dime. Seeing one in daylight usually means there are more.
- 1Gnaw marks on food packaging, wood trim, or wiring.
- 2Chewed holes in the bottom of cabinets or drawers.
- 3Burrow holes along the foundation, deck, or shed.
- 4Live sighting, especially during the day.
- 5Greasy rub marks along baseboards, beams, and pipe runs.
- 6Pets staring at or pawing at a wall or appliance.
Why it’s worth acting soon
- Mice breed fast, every few weeks.
- Droppings and urine contaminate food and insulation.
- Gnawed wiring can be a fire risk.
- Nests and odor get harder to clean the longer they stay.
Treatment options and typical costs
Inspection and Entry-Point Mapping
$75–$250
First, the pro maps where rodents get in. That map guides the traps and sealing.
- Time
- 60–90 minutes
- Best for
- Every job; nothing else works without it
Tamper-Resistant Exterior Bait Stations
$100–$300 setup, $40–$80 per service visit
This is a maintenance tool, not a one-time fix. In Derry neighborhoods with steady rat pressure from alleys, creeks, or restaurants, stations are checked and refilled on a schedule.
- Time
- 30–45 minutes per visit, ongoing
- Best for
- Outdoor rat pressure; ongoing perimeter protection
Follow-Up Monitoring
$50–$150 per visit, or included in a plan
Ask what happens if activity returns during the monitoring period. Many re-trap and re-seal under the same agreement. Confirm first.
- Time
- 20–40 minutes per visit
- Best for
- Confirming the house stays clear after treatment
Attic and Crawlspace Cleanup and Sanitation
$500–$3,000, higher if insulation is replaced
After the rodents are gone, what they left behind still matters. Cleanup in Derry attics means removing droppings, nesting material, and urine-soaked insulation, then disinfecting the surfaces underneath.
- Time
- Half day to two days
- Best for
- Heavy contamination; odor, urine-soaked insulation, nesting
Prices are typical published ranges. Ask what’s included before you compare quotes.
Rats can travel plumbing, so a sink or floor drain with a missing strainer is worth fixing; a tight strainer or grate keeps them out.Which rodents live around Derry.
Norway rats are the other usual suspect. They burrow along foundations and enter low. House mice are the most common rodent in Derry homes. They're small, curious and breed quickly.
When they move in.
Check for gaps before then. Spring is breeding season. Small problems grow fast.
This is what a proper seal looks like: metal mesh fastened with screws and sealed at the edges. Foam or caulk on its own gets chewed through.How they get into houses here.
Look at the dryer vent flap. Window wells need covers or screens. Homes from Derry out to Londonderry and Salem share the same weak spots, so the checklist below works across the area. Plenty of homes in Derry have basements. Rodents use gaps around utility lines, dryer vents and window wells. Check where pipes and cables enter.
A year of rodents in Derry.
- Spring: breeding season. Act on any sign quickly. - Summer: with highs around 82°F in Derry, rodents look for water. Fix drips and leaks. - Fall: mice move indoors as nights cool. Seal gaps in September. - Winter: with lows near 15°F in Derry, check the attic, garage and pantry for droppings.
Mice or rats?
- Sounds: mice sound light and quick. Rats sound heavier. - Behavior: mice are curious about new traps. Rats avoid them for days. - Rub marks: rats leave greasy smudges along walls and beams. - Droppings: mouse droppings are rice-sized. Rat droppings are two or three times bigger. - Holes: mice chew dime-sized holes. Rats chew holes closer to quarter-sized.
Sealing small gaps yourself.
- Hardware cloth: use quarter-inch mesh over vents and larger holes. - Door sweeps: close the gap under garage and exterior doors. - Expanding foam: fine on top of mesh, useless on its own. - Check your work: daylight through a gap means it isn’t sealed. - Steel wool or copper mesh: pack it into small gaps first. - Sealant or mortar: cover the mesh so it stays put.
Cleaning up droppings safely.
- Spray droppings with a bleach solution, then wait five minutes. - Wipe up with paper towels and bag them. - Don’t sweep or vacuum droppings dry. It stirs up dust. - Wash your gloved hands, then your hands. - Air the room out for 30 minutes first. - Wear rubber or plastic gloves.
What happens at an inspection.
Most inspections take about an hour. The inspector walks the outside first. They check the foundation, vents, rooflines and utility gaps. Inside, they check the kitchen, garage and attic. You should come away with a list of entry points. Photos help.
Rodents in the car.
Mice and rats nest in engine bays and chew wiring. Park in a closed garage when you can. Check the air filter box for nesting. Clear birdseed and pet food from the garage.
Bird feeders and rodents.
Spilled seed feeds mice and rats. Use a seed tray and sweep up spills. If rodents show up, bring feeders in at night. Store seed in a metal can with a tight lid.
Questions to ask before you sign.
- How many trap visits are included? - What happens if they come back? - Is cleanup included, or extra? - Will you use poison inside? (Ask them not to.) - Where are they getting in? - Which gaps will you seal, and with what?
Rodents by the numbers.
For Derry homes, those three findings — species, entry points, and scale — are what a quote should be built on, not a regional average. For Derry homes, ask any provider to show you the entry points and the plan before you compare numbers. National surveys set rough expectations but cannot diagnose one house. For Derry homes, what actually matters is a walk-through: where the droppings are, how the rodents are getting in, and how large the colony is.
What affects the price
- Mice versus rats; rats take longer and cost more.
- Follow-up visits included versus billed separately.
- Whether insulation must be removed and replaced.
- Materials used for sealing: mesh, sheet metal, mortar.
- Number of entry points found during inspection.
- Number of trapping visits needed to reach zero.
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What's your biggest concern about rodents?
When to call for help
Call right away if you see rats. They take a longer, more careful approach. Attic cleanup is hard to do safely without training. Call if you hear them in the attic or walls. Droppings in several rooms are another sign. So is a dead-rodent smell.
What you can do yourself
Seal small gaps with steel wool and sealant. Rooflines, vents and attics are harder. That's where a pro's sealing work pays off. Start tonight with snap traps along the walls. Bait them with peanut butter. Store food in sealed bins.
Rodents in Derry
In Derry's neighborhoods, woodpiles, fences, bird feeders and gardens draw rodents close to the house. A typical home in Derry is worth around $375k, and chewed wiring or soiled insulation can get expensive. For Derry homes, the humid continental climate means rodents activity tends to follow fall and winter (rodents move indoors for warmth), so scheduling the visit before the busy stretch usually means a faster response and a cleaner quote. With about 44 inches of rain a year, Derry gives rodents plenty of water, so food and shelter are what you control. Winter lows average around 15°F in Derry, and that cold is what sends mice looking for a way in.
Local research
Rodents in Derry, NH: what the public record shows
Before you compare quotes, it helps to know which rodents actually live in New Hampshire, when they are busiest around Derry, and what the state figures look like. Everything below links to the agency or university page it came from.
Wildlife tested that had rodenticide exposure
Necropsies at the NH Veterinary Diagnostic Laboratory found exposure statewide, often to long-acting second-generation anticoagulants.
University of New Hampshire ExtensionDays from a lethal anticoagulant dose to death
Rodents keep feeding after taking a lethal dose, so carcasses carry far more poison than one dose to hawks, owls and pets.
University of New Hampshire ExtensionRodent species recorded in New Hampshire
- House mouse (Mus musculus) — Enters at 1/4 inch; 5-10 litters per year; eats about 200 small meals a night.
- Norway rat (Rattus norvegicus) — Burrowing rat of basements, sewers and ground floors; tail shorter than head plus body.
- Deer mouse (Peromyscus maniculatus) — Primary U.S. hantavirus carrier; lives throughout Washington and the interior West.
When rodents are busiest around Derry
Fall entry; winter infestations. Upper Midwest and Northeast: mice in walls and garages all winter.
Based on Derry’s humid continental climate profile.
UNH Extension pushes trapping and exclusion over bait because of documented secondary poisoning in New Hampshire raptors.
For context, nationally
- 1/4 inch (the width of a pencil) — Smallest gap a mouse can enter. CDC
- 890; 35% fatal; 94% west of the Mississippi — Hantavirus cases reported since 1993 (through 2023). CDC
Sources: University of New Hampshire Extension; CDC; Pest Notes: House Mouse; Pest Notes: Rats; Hantavirus. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep rodents away
- Inspect vehicle engine bays if parked near fields or woods.
- Trim tree branches at least six feet from the roof.
- Stack firewood off the ground and away from the house.
- Seal the gap where the garage slab meets the wall.
- Install brush or rubber door sweeps on exterior doors.
- Store pet food and birdseed in sealed metal containers.
Before you call, sketch where you have seen droppings or heard noise and measure any gaps you found. It makes the first visit faster and the quotes comparable.Did you know?
A mouse's heart beats around 500 times a minute.
For Derry homes, rats are strong swimmers and can tread water for a long time, which is why they sometimes travel sewer lines.
Questions people ask
Is it safe to clean up droppings myself?
Wait five minutes, then wipe up with paper towels. Never sweep or vacuum them dry. For small amounts, yes, with care. Wear gloves and spray the droppings with a bleach solution.
Why do rodents keep coming back every year?
Traps remove the rodents inside. New ones follow the same path in. Usually because the entry points were never sealed.
What does a rodent inspection involve?
Inside, they look at the kitchen, attic, garage and under sinks. You should get a list of entry points. The inspector checks the outside walls, roofline, vents and utility gaps.
How do I know if I have mice or rats?
Mouse droppings are about the size of a rice grain. Rats also chew larger holes and sound heavier at night. Check the droppings.
Do ultrasonic repellers work?
It doesn't pass through walls either. Sealing and trapping work better. Not reliably. Rodents get used to the sound within days.
Does a house with structural problems attract more rodents?
Census Bureau's 2019 American Housing Survey (AHS). Ask every Derry company you get a quote from what they tend to find in your part of town. The two go together, at least in the data. Homes with sloping, leaning or buckling outside walls were 5.6 times as likely to report rodent sightings in the U.S.
Where in the house are mice most often found?
homeowners, 37% reported a sighting in the kitchen. A good pro in Derry will explain how their plan fits what they found at your home. The kitchen leads. Among homeowners who had ever encountered rodents in the National Pest Management Association's (NPMA) September 2022 Harris Poll of more than 1,300 U.S.
Are rodents a problem in Derry?
They're common here, as almost everywhere. House mice cause most problems.
Nearby cities
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Sources (11)
The facts in this article come from the public sources listed above. Every home is different, so ask the company you talk to about pricing and what’s included. Published by Rodent Exterminator · Updated September 11, 2026 · How we write these guides