How Do Exterminators Get Rid of Mice? The 5-Step Process We Use on Long Island

1. Inspection. Droppings, gnaw marks, rub marks, and odor. UC IPM says to look for droppings, fresh gnaw marks, and tracks, and notes a musky odor is commonly associated with mice. Penn State describes the droppings as pointed and about the size of a grain of rice.
2. Exclusion. The CDC says mice can fit through a hole the width of a pencil, a quarter inch, and lists the usual entries: gaps around pipes under sinks and behind appliances, utility line openings, vents, foundation gaps, and door and window frames. UC IPM calls exclusion the most successful and permanent form of house mouse control. Gaps get copper mesh or hardware cloth backed with sealant, or metal and cement for the larger ones. UC IPM says steel wool makes a good temporary plug but may rust, and that expanding foam and other gnawable materials are ineffective on their own.
3. Trapping on the runways. UC IPM says to place traps close to walls so mice pass directly over the trigger, and Penn State notes mice tend to run along the wall. Traps indoors, not poison; Penn State says to avoid rodenticides inside homes because rodents die inside walls and smell bad, attracting insect pests.
4. Sanitation and monitoring. Sealed food, cleared clutter, and monitors to read activity. UC IPM notes that while good sanitation seldom completely controls house mice, poor sanitation attracts them.
5. Follow-up until zero. We come back, check the traps and monitors, and close anything we missed.

Rice grain droppings, scratching at night, and a musky smell. UC IPM says house mice are active mostly at night but can occasionally be seen in daylight. Droppings along the back of a counter, in the cabinet under the sink, or along a garage wall are the reliable sign. So is a chewed corner on a cereal box.

Through quarter inch gaps, mostly at ground level, mostly in fall. UC IPM says that where outdoor populations exist, mice frequently enter homes in autumn when nighttime temperatures become colder. The gaps are the ones the CDC lists: the hole where the gas line enters, the gap under the garage door, the dryer vent with no screen, the space around the sillcock. Once inside they do not go far; UC IPM says house mice seldom venture more than 30 feet from their nest and food supply.

Not with a warm house and a food supply. UC IPM says a female may have 5 to 10 litters a year of about 5 or 6 pups each, born 18 to 21 days after conception, with the young sexually mature at 5 to 6 weeks. A pair in October is a population by January.

None that hold up. UC's pest experts state that predator scent or urine, ultrasonic devices, dryer sheets, soap bars, and mothballs do not work, and that rodents quickly become accustomed to these sounds or smells. Cornell's IPM program says scientific evaluations of ultrasonic devices found no effect on rodents. NPIC adds that mothballs have little or no effect as repellents. Peppermint oil is in the same category. Save the money for the hardware cloth.

Not indoors, and only in locked stations outdoors. Penn State and UC IPM both warn that rodenticide use often results in mice dying inside the structure. Massachusetts' rodenticide page notes that pets and children are at risk from household rodenticides and that birds of prey, including red-tailed hawks and owls, are affected by eating poisoned rodents. UC IPM's rule is bait only in tamper-proof stations out of reach of children, pets, and wildlife. That is why our program is traps indoors and locked bait stations outdoors, serviced by a licensed applicator.

How many entry points need sealing, the size of the house, whether the attic or crawl space is involved, and how many follow-ups it takes. Mice get a written quote, free, before any work begins, and the job carries a 60-day written guarantee. Be wary of a quote that lists traps and poison and no sealing; UC IPM says exclusion is the permanent part.