Getting rid of rats

The roof rat that has settled in Southern Nevada is also known as an Old World or European rat, and has been living near human populations for thousands of years. Roof rats came to America aboard ships centuries ago. They were in the hold of Christopher Columbus's flagship, the Santa Maria. Rats were so common down below that it was against Spanish maritime policy for sailors to sleep in the hold.

It is believed that roof rats first appeared in Southern Nevada in the early 1990s. The critters first appeared in Phoenix much later. Rats were discovered in the Arcadia neighborhood in East Phoenix three years ago.

Roof rats are nocturnal. They forage at night and are rarely seen during the day unless competition for food or habitat is significant. If you see a rat near your home, it's likely his nest is close by. Rats, which have notoriously poor eyesight, don't stray far from home.

Besides roof rats, Norway rats, which are a little larger, more aggressive and more likely to thrive in unsanitary conditions, have appeared sporadically in recent years in Southern Nevada. Still, sightings are rare.

Recently, reports of roof rat sightings have increased throughout the Las Vegas Valley. To control these pesky rodents, the Clark County Health District advises:

• Weatherproof your home's windows and doors. Eliminate light from around doors. Seal outer openings, pipe chases and wire entrance gaps with steel wool, sheet steel aluminum, or wire mesh. Also, block "doggy doors" at night or you might see an animal at the dog dish that doesn't look at all like your Shih Tzu.

• Eliminate unnecessary clutter, material, brush or foliage from your property. Keep bushes trimmed and clean out leaf litter and clutter that collects below bushes. Remove landscaping debris quickly. Stack firewood 12 inches off the ground.

• Keep trash cans (plastic or metal) covered. Do not put out "food" garbage in plastic bags. Place sealed plastic bags in trash cans. Do not leave pet food outside overnight.

• It's a good idea to hire an exterminator who works for a commercial pest control company that is licensed by the Nevada Department of Agriculture. After rodent-proofing, glue and snap-type traps are effective in reducing rodent numbers. Do not place traps where they may be accessible to children or pets. Over-the-counter poison baits can also be useful, provided the label directions are followed, but should not be used in households with children or pets, unless under the direction of a licensed pest control company.