Here’s What to Do if You Smell a Rat
Question: While sitting on my patio, I saw a large rodent run across my fence. Could I have rats?
J.B., Anaheim
Answer: In Orange County, the roof rat (Rattus rattus) is responsible for the majority of problems. They are agile climbers with great balance, and often use fences and utility lines to move about. They have a tail that is longer than their entire body (7 1/2 to 10 inches long versus mice with a 2 1/2-inch to 4-inch long tail).
Aside from visual sightings such as running across the top of a fence, the following signs indicate roof rat activity:
* Evidence of 1/2-inch spindle-shaped dark rat droppings close to a nesting site, feeding location or route of travel. You may also find them in swimming pool heater covers, water heater closets and forced air heaters where their urine will also leave a very pungent smell.
* As rats repeatedly brush up against painted surfaces or wooden beams, the oil from their body will rub off and leave greasy marks.
* Evidence of gnawing on wood, plastic, rubber and electrical wires.
* Empty snail shells under bushes, near nesting sites or on fences. The rats eat the center portion out of the shell to get the snail.
* Damaged or partially eaten hollowed out oranges, avocados and other fruit.
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The roof rat diet consists of a variety of fruits and nuts such as oranges, avocados, plums, peaches, apricots and walnuts. Pet food and ivy are also a lure for them. Rats will even eat grass seed, bird seed and pet droppings.
Roof rats like to establish nests in many of our most common backyard plants such as Algerian ivy, bougainvillea, cape honeysuckle, creeping fig, Italian cypress, natal plum, palm trees, oleander and yucca.
Dense shrubbery of almost any type would make a suitable nest for a roof rat, but these plants provide food and a home.
Barbecues, storage boxes, our homes, garages and utility sheds have also been known to shelter rats.
When storing wood and lumber, use racks that are 18 inches off the ground and 12 inches away from walls.
Rats are considered vectors (capable of transmitting disease to humans), and because of this, care should be taken in dealing with them.
This summer, the Orange County Vector Control District confirmed it had detected the deadly hantavirus in roof rats. It is advising county residents to use extra caution when removing rodent carcasses or cleaning up rodent droppings.
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The following are the recommended precautions: Mist the droppings (and carcasses) from above with a mixture of one part household bleach to nine parts water and wet to the point of just being damp, but not soaked. They should then be gathered up, placed in a double plastic bag, and disposed of.
Dry droppings should not be swept or otherwise handled because of the possibility of dust particles being inhaled. Dust masks with HEPA filters and rubber gloves are recommended when dealing with rat droppings.
If you live in Orange County and believe you have a rat problem, contact the Orange County Vector Control District at (714) 971-2421; South County residents call (800) 734-2421.
A Vector Control technician will come to your home free of charge and inspect the surroundings, advising you on proper control of roof rats.
You can request a handout on plant substitutions through Vector Control. There is also free literature on roof rats in Spanish and English.
For a rat or mouse problem in your home, call a private pest control company.
Have a problem in your yard? University of California Cooperative Extension (UCCE) Master Gardeners are here to help. These trained and certified horticultural volunteers are dedicated to extending research-based, scientifically accurate information to the public about home horticulture and pest management. They are involved with a variety of outreach programs, including the UCCE Master Garden hotline, which provides answers to specific questions. You can reach the hotline at (714) 708-1646 or send e-mail to ucmastergardeners@yahoo.com. Calls and e-mail are picked up daily and are generally returned within two to three days.
