Oh Rats! By Mike Kobus

Thump, thump, and thump. Scratch, scratch, and scratch. Gnaw, gnaw, and gnaw. It’s late at night; you are trying to sleep but there is something in the walls and ceiling keeping you awake.. Every night it's the same. What is it that is making that racket? Is the house haunted? Maybe the ghost of some restless gold miner has decided to set up shop in your attic. Unfortunately, what is happening is not as cool as a haunted house. More than likely what is going on is that you have acquired some type of rodent. Although I often come across larger rodents living in structures, the most common to invade your house are rats and mice. And the rule of thumb is; if you can hear them, it is probably rats. Here in El Dorado County we most often deal with roof rats. Roof rats are a long and slender creature with a pointed nose, long ears, and a long tail. The rat uses its long tail as a balance to enable it to climb just about anything. Rat’s teeth can grow up to 5 inches per year so they must continually gnaw to grind them down. Gnawing can usually be heard when rats have invaded your house and can cause serious damage to wood, drywall, wiring, and other electrical systems. If rats come knocking, a homeowner would be wise to do something about it. 

During the summer months, rats are primarily outside. But as fall and winter approach, rats seek shelter from the elements. Your house offers an inviting place for rats to live during the cold winter months. This year there seems to be an extremely large number of rats invading structures, many more than most years. I’m not sure exactly why this has occurred but I have a theory. Since we had so much rain in late spring and early summer many of the grasses and seeds that rats live on thrived providing a larger-than-normal food base for the rats to live on. To simplify it; more food means more rats. 

The most effective way to rid your house of rats is to exclude them. The only problem with exclusion is finding the entrance points. When inspecting a house for entrance points one must take into consideration the resourceful nature of rats. Rats can climb just about anything. They can jump 3 feet vertically and 5 feet horizontally. Rat’s bones are very pliable which allows them to squeeze through openings about the size of a quarter so any inspection should be very thorough. The first thing a homeowner should do is to eliminate trees from touching the house up around the roofline. This is one of the most common routes of entry for rats. Any screens that are missing or broken should be replaced and any openings to the sub-area should be repaired. Areas of the house where two different angles of the roof meet such as gables should be inspected for openings. Garages are usually pretty accessible to rodents and many garages have openings into walls or the sub-area that might be concealed by cabinets or appliances. Another area to look at is where tubing from the air conditioning unit enters the house. Seal any and all openings with an appropriate material. Steel wool stuffed in smaller holes makes an excellent quick fix but will rust and can stain the side of a house. 

Rodent-proofing a house may be all that is needed to keep rats out of your home. If an infestation of rats persists after exclusion I recommend trapping. Using a good old spring snap trap is very effective. When putting out snap traps always put them against a wall or something the rats will run along. Rats are very blind and use their whiskers to feel their way along runways. Another trick is to “Pre-bait” your traps. Put several traps out, and bait them with peanut butter or something similar, but don't set the trigger. Rats are very intelligent and shy around new things. Let the rats start eating off the traps, and then set them. Pre-baiting the traps will usually result in more rats being caught.

Another way to control rodents is with the use of rodenticide bait. Although at Koby Pest Control we try to avoid using rodenticide bait in a residential setting. The problem with rodenticides is that one can never be sure where the rodent will die. The theory behind rodenticides is that they are anticoagulants and will make the rat thirsty. Instinctually, rats know they can find water outside so hopefully; the varmint will make it outside before it dies. Unfortunately, that does not always occur. There have been many times when I have been called to a house because of a dead animal smell. Usually what has occurred is the homeowner has used an over-the-counter rodenticide and a rat has expired in a wall void or other inaccessible area. Although the smell will eventually dissipate, it can be very uncomfortable for serval days. At Koby Pest Control we do have products that can absorb or mask the offensive odor. But in any case, I feel that trapping is a safer way to eliminate rodents.