How to Protect Your Home from Rodents in Winter

The first cool nights of the year arrive in the Temecula Valley sometime in November, and the questions change. All summer it's ants and spiders. Then one week it's scratching in the ceiling in Murrieta, droppings along the garage wall in Menifee and a chewed bag of dog food in a Wildomar pantry. Rats and mice don't hibernate, and our winters are mild anyway. What changes is that the nights get cool, the outdoor food gets scarce and a warm attic above a kitchen becomes the best address in the neighborhood.

This is a homeowner's guide to keeping them out: which rodent you're likely dealing with, where they get in, what to seal the gaps with so the fix lasts, what in the yard is giving roof rats a road to your roof, and how to store food so the house isn't worth the trip. If they're already inside, our rodent control page covers the service, and Dylan Reed does our rodent work. This post is about the walk-around you can do yourself this weekend.

Why rats and mice move indoors when Temecula nights cool down

Three things line up in late fall. The nights turn cold, the natural food the rodents lived on all summer, fallen fruit, seeds, insects and irrigated garden plants, thins out, and the year's young are looking for territory. A house answers all three. The attic is warmer than the palm tree, the pantry and the garage are stocked, and the gap under the roof tile is open every night. UC IPM describes roof rats as living up in trees, palms, thick vines and attics and moving along fences and utility lines, which is a description of a Murrieta backyard. The Norway rat, heavier and ground-level, moves into garages, sheds and burrows along the foundation. The house mouse, which lives alongside people wherever they are, simply walks in under the garage door. None of them are new arrivals to the neighborhood. They've been in the fence line and the ivy all year. Winter is when the house becomes the better option, and sealing it is how you change that math.

Is it a roof rat or a mouse in my attic?

Scratching in the ceiling at night in the Temecula Valley is most often a roof rat, because roof rats are climbers. Roof rats are slender with a tail longer than the body, and they leave spindle-shaped droppings about 1/2 inch long along the attic runways, on top of the garage walls and near the fruit tree. You'll hear them after dark, running the length of the house along a joist. House mice are a fraction of the size, leave much smaller droppings with pointed ends in large numbers along garage walls, under sinks and in pantry corners, and you'll find shredded paper or insulation nests in a drawer or behind the water heater. Norway rats are the heavy ones, with a blunt nose and a tail shorter than the body, and they show up at ground level: burrows along the foundation, under the shed, behind the trash cans. UC IPM's Pest Notes on rats and house mice have the comparison. It matters because the entry points differ.

Where do rodents get into a Riverside County home?

Check these seven places. The eave line, where the first course of roof tile meets the fascia and leaves a gap a rat climbs straight into. Attic and crawl space vents with a torn or missing screen. The hole around the air conditioning line, gas line or cable where it enters the wall, which the installer left open. The garage door, where the rubber seal is chewed or the bottom corners don't meet the slab. The dryer vent with no flap. The gap under a slider or a side door with no sweep. And the weep screed and stucco cracks at the base of the wall, especially behind shrubs. Go around the outside at dusk with a flashlight and look at each one. A quarter inch is a mouse door and a half inch is a rat door, per UC IPM, so a pencil tests the first and your finger the second. Mark each gap with tape so you can find it again in daylight, and start the list with the roofline, because that's the roof rat's door.

Which materials keep rodents out and which don't?

Rodents chew, so the material has to be something they can't get their teeth through. What holds: galvanized hardware cloth with a quarter-inch mesh over vents and large openings, sheet metal flashing at the eave gap and the garage door corners, copper or stainless steel mesh packed tight into holes around pipes and lines, mortar or concrete patch at the base of the wall, and a new rubber seal plus metal corner plugs on the garage door. What doesn't hold on its own: expanding foam, caulk, plastic and wood filler. Foam and caulk are fine as a finish over metal and useless as the barrier itself, which matches UC IPM's exclusion advice: metal packed in first, caulk over it. Two details that matter: fill the gap all the way through rather than capping it, because a rat will dig behind a shallow patch, and do the eave line carefully, since roof rats are up there every night testing it. If you'd rather not be on a ladder in December, that's the exclusion work we quote.

What in my yard is giving roof rats a route to the roof?

Anything that touches the roofline or the fence. Roof rats travel high, as UC IPM describes, so the queen palm with fronds brushing the tile, the bougainvillea climbing the block wall to the eave, the orange or lemon tree with branches over the patio cover and the cable line running from the pole to the corner of the house are all roads. Trim trees and vines back from the roof so there's clear air between them and the house, and keep ivy off the walls, because it's both a ladder and a nest. Pick up fallen fruit and pick the tree when it's ripe rather than leaving it on the branches all winter, since citrus left on the tree feeds roof rats for months, which is how a clean house in Temecula or Menifee ends up with them. Get the woodpile up on a rack and well clear of the house. Keep trash and recycling lids shut and bring the dog's bowl in at night. Open up the dense shrubs along the foundation so there's nowhere to sit at the base of the wall. None of it needs a product. All of it removes a reason to visit.

How should I store food in the garage and pantry?

In containers a rodent can't chew through, which rules out the bag it came in. The garage is the main problem in winter, because that's where the dog food, the bird seed, the bulk rice from the warehouse store and the holiday baking supplies end up. Put all of it in metal or heavy, hard plastic bins with lids that latch, and keep the bins off the floor. Feed pets at set times and lift the bowl afterward rather than leaving kibble down all day. Inside, move cereal, pasta, flour, sugar, nuts and crackers into sealed jars or bins, clean the pantry floor and the corners of the shelves where the crumbs collect, and check behind the refrigerator and under the stove, which is where a mouse finds a winter's worth of food without ever being seen. Rinse recycling before it goes in the bin. UC IPM lists food, water and shelter as what decides whether a rodent stays, and the pantry is the first one. A house with nothing to eat gets explored and then left.

What are the signs rodents are already inside?

Droppings first, because they're the sign you'll find without looking for it: along the garage walls, on the attic insulation, in the back of the pantry, under the kitchen sink, on top of the water heater. Then sounds: scratching, running and gnawing in the ceiling or walls after dark, which stops when you turn the lights on. Then gnaw marks on food packaging, the bottom of a door, the garage door seal, plastic bins and, worst of all, wiring in the attic. Then the greasy rub marks a rat leaves where it runs the same route every night along a pipe, a beam or the top of a wall. Then nests of shredded paper and insulation in a drawer, a box or a corner of the attic, and a musty smell in a closed room. Chewed fruit still on the tree with a hole in the rind is the outdoor sign. One of these is reason to walk the house for gaps this weekend. Several together, especially the sounds, mean the rodents have moved in rather than passed through, and that's the point to call.

When to call us about rodents

When they're already inside, when you've sealed what you can find and the noise continues, or when the gaps are on the roofline and you'd rather not be up there. Our rodent work is trapping and exclusion, which means sealing the gaps they use, and we quote the exclusion separately so you can see what the sealing costs on its own. Any bait we use goes in tamper-resistant bait stations. What you can do before the call makes the visit more useful: note where you hear the noise and at what time, where the droppings are, which gaps you found on your walk-around and what you've already sealed, and whether there's a fruit tree, a palm or a vine touching the roof. You don't need to be home for the visit. Call (951) 535-4220 and Jenni will slot you in. We're based in Murrieta and cover Temecula, Menifee, Lake Elsinore, Hemet, Perris and Riverside, plus Fallbrook, Escondido, Vista, Oceanside and Carlsbad in North County.