Woodrats, the native pack rats of the El Paso area, build their nests in sheltered spots. Texas Tech's Mammals of Texas says they prefer cactus and rock crevices and build middens from sticks, cactus joints and rubbish. A vehicle that sits for days, in a carport, beside a wall or in a garage with gaps, offers the same kind of shelter, and the engine bay is the most protected part of it.
If you open the hood and find sticks, cactus bits, paper, droppings or chewed insulation, a rodent has been living there. Here is how to check, how to clean it out safely and how to make the spot less inviting.
Signs a rodent has been in your vehicle
Look before you start the engine on any vehicle that has been sitting.
- Sticks, twigs, cactus pieces, leaves or shredded paper on top of the engine or tucked near the battery and air filter box
- Droppings on the engine cover, the fender wells or the floor of the garage under the car
- Chewed wire insulation, hoses or the hood liner
- A musty or urine smell when the fan or heater runs
- Debris or nesting in the cabin air filter housing
Chewed wiring can cause warning lights, rough running or a no-start. Have a mechanic check any damaged wiring before you use the vehicle.
Why vehicles attract them
Woodrats look for protected places to build. Engine bays are enclosed, shaded and hard for predators to reach. Vehicles that sit beside prickly pear, rock landscaping, woodpiles or junk give a woodrat an easy move from its old cover to a new one.
Seasons matter too. Texas Tech says the woodrat's main breeding season runs from January through September. Nest building and young animals looking for new territory can bring more activity in those months. Other rodents, including mice, also nest in vehicles, so the same steps apply.
How to clean out a nest safely
Nests hold droppings and urine, and deer mice, the main US hantavirus carrier according to the CDC, live in the same areas. Treat a vehicle nest the way the CDC says to treat any rodent nest.
- Open the hood and garage door and let the area air out for 30 minutes.
- Wear rubber or plastic gloves, plus a mask for a large nest.
- Spray the nest and droppings with a bleach solution or disinfectant until soaked, and wait 5 minutes.
- Remove the material by hand or with paper towels into a plastic bag. Seal it, double-bag it and put it in a covered can.
- Do not use a shop vacuum or compressed air on dry droppings.
- Wash gloved hands, remove the gloves, then wash your hands with soap and warm water.
How to keep them out
No product guarantees a pack rat will skip your car. These steps cut the odds.
- Park in a garage that is sealed. Replace worn bottom and side seals so gaps are no more than a quarter inch, the limit extension guidance recommends for doors.
- Move the vehicle regularly. A car that moves every day is less attractive than one that sits.
- Clear cactus, rock piles, woodpiles and junk away from where you park. The CDC suggests keeping woodpiles 100 feet from the home and moving abandoned vehicles more than 100 feet away.
- Do not store pet food, bird seed or grass seed in the garage unless it is in metal cans.
- Leave the hood up on vehicles in long storage, so the engine bay is less dark and enclosed.
- Set traps in locked stations near where you park if you see signs.
Mothballs come up a lot in online advice. They are pesticides, and the label is the law. A University of Florida IFAS fact sheet says outdoor placement is the most common misuse and that mothballs can harm people, pets and wildlife. Our repellents article covers the alternatives.
RVs, trailers and equipment
RVs, travel trailers, boats and lawn equipment sit for long stretches, which makes them prime spots. Before a trip, open compartments and check for sticks, droppings and chewed wiring. Clean anything you find with the CDC wet method before you sweep or vacuum. Store them in a sealed building if you can, or away from brush and cactus if you cannot. If you find a nest more than once, a technician can trap around the storage spot and help seal the building. See our pack rat control page.
If it keeps happening
Repeat nests mean there is an active woodrat population nearby. A technician can find middens in the yard or a neighbor's lot, trap the animals and seal the garage. See our garage rodent control page and pack rat control page.
Frequently asked questions
Will my car insurance cover rodent damage?
Coverage depends on your policy. Ask your insurer and keep photos and repair estimates.
Do pack rats only nest in cars that sit?
Vehicles that sit are the most common target, but any sheltered, rarely disturbed space can attract them.
Do peppermint oil or mothballs keep them away?
There is little evidence for scent repellents, and mothballs are pesticides that should only be used as the label directs.
Is it safe to remove the nest myself?
Yes, with gloves and the CDC wet-cleaning method. Never vacuum or blow out dry droppings.
How often should I check under the hood?
Check any vehicle that has sat for a week or more before you start it, and more often if you have seen sticks or droppings nearby.
Sources
- Texas Tech University, Mammals of Texas: White-toothed woodrat
- CDC: How to clean up after rodents
- CDC: How to seal up to prevent rodents
- Wildlife Damage Management, eXtension: Rodent exclusion methods
- University of Florida IFAS: The Facts about Mothballs (PI289)