Oh Rats!
Originally appeared in Hills Publications, October 16, 1998
Common throughout California, yet rarely mentioned in real estate sections, rodent pests are usually discussed only in hushed tones. Despite the fact that many people are in denial, these scurrying creatures are permanent denizens of even our nicest, priciest neighborhoods, including Piedmont and Orinda.
A respected, experienced local home inspector told me that 80 per cent of the homes he inspects show evidence of rodent activity in the basement, crawl space or attic. A majority of homeowners and buyers with whom I speak, however, are surprised to learn of the issue. They are not able to identify the three most common rodents, nor do they know how to deal with them.
Mice and rats evoke a variety of negative responses, from annoyance to fear and loathing. You may think, or hope, you will never come in contact with one of these pests, but think again. Since they are so widely found, it is important to at least be aware of some basic information about them.
Rodents like large families
Our friends once had an episode with a marauding house mouse. After chewing some foam from their sofa, he (or she) disappeared, never to be heard from again. This was fortunate because, depending on whether you are talking about rats or mice, they can produce up to eight litters per year with as many as 12 per litter.
Home sweet home
Mice usually live in fields, but would love to move into a cozy building – or your home. This is especially true in winter. In a house, they occupy walls, cabinets, closets and furniture.
When you hear the word “rat,” it is probably the Norway rat you are picturing. Burrowing and digging is how they try to enter our homes. Since they cannot dig up through concrete, a slab over the soil in the basement or crawl space of a house provides one type of rat-proofing. Another favorite form of entry is through a broken sewer line and up into your plumbing.
A sound you may think is a squirrel or cat running across your roof may, in fact, be your new upstairs neighbor – a roof rat. Nimble climbers, they can easily scale trees, telephone poles and lines, wires, pipes and wall studs, entering your home through holes as small as one-half inch.
Roof rats are excellent leapers. They can jump vertically 36″, horizontally48″, and can bound eight feet from a tree to a house. Along with trees, they nest in shrubs, ivy, woodpiles, sewers and storm drains. These creatures have become more prevalent in our area in the past 15 years.
Signs of a break-in
Droppings are an obvious clue, but there are other signals of an uninvited presence. Rats are continually gnawing. Their teeth can grow more than five inches a year; they need to gnaw to shorten and sharpen them.
Roof rats have been known to cause fires by chewing through electrical wiring. One busy roof rat, by scratching, clawing and scrambling, can sound like an army. They tend to be most active at night. If you hear sounds from your attic, do not ignore them.
Other indicators are outdoor paths or runways where grass is beaten down; oil or grease smudge marks in runways; urine stains and odors. One classic sign is an agitated or excited cat or dog. This could be your first warning of a rodent invasion.
Evicting the critters
Rats leave scent trails that may last for years. A couple we know successfully eradicated roof rats only to have them return three years later. Mice can come and go through holes no bigger than a pencil eraser. Before you can get rid of these pesky rodents, you must acknowledge the problem. Once you have done that, you have a number of options.
- Vector control. Call your local city or county vector control agency. They will send out a technician who will help you ascertain the situation and give you advice.
- Pest control operator. If you contact a private contractor, make sure it is someone with experience who understands what to look for and what to do. You want to know who your visitor is, where it is getting in and how to give it the boot. Keep in mind these animals are intelligent and generally have more than one way in and out of your home.
- Improve sanitation. Check for any food or garbage accessible to the rodents. Cat or dog food left outdoors is an invitation for infestation.
- Remove vegetation. Ivy, high grass and bushes close to the house attract rodents and can provide nesting sites. Cut them back.
- Traps or baits. If you use a trap, cage or bait, you can expect either a live rodent that must now be disposed of, or a foul-smelling dead one. Neither choice is attractive.
- Cats. Some indoor/outdoor cats are effective hunters and will keep rodents at bay; others are just pussycats.
- Rat-proofing. Even if holes are too small, mice and rats are incredibly adept at enlarging them by chewing and scratching. Preventive techniques include using materials such as sheet metal, steel wool, metal screening, or concrete to:
- block openings around and in air vents, exhaust fans, sewer and water
- pipes and cables
- repair foundation and/or exterior cracks or holes
- seal roof openings and repair soffits
- pour concrete over earthen floors in basements and/or crawl spaces
Final Thoughts
Rodent pests are a natural, albeit unpleasant, aspect of our lives. Where there are people, mice and rats abound, unless you move to Antarctica.
Notwithstanding state law, which requires sellers to fully disclose problems about their property, I rarely see sellers mention past or present rodent activity. Discomfort or embarrassment prevents some people from confronting this issue.
If you have, or think you might have rodents in your house, accept reality and do something about it soon. Waiting will definitely multiply your difficulties. Better still, do some preventive maintenance now.
Rodent research was derived from various Internet articles and my interview of Jim Rounds, a local pest control operator and trapper since 1957. Thanks to home inspector John Brogan for his assistance.