Rodents

Rats and mice cause millions of dollars of damage in food alone in the state of Hawaii every year. Additionally they can carry and readily transmit many significant diseases.

The 4 rodents commonly found in Hawaii are: 1) the house or field mouse, 2) the roof or black rat, 3) the Norway or brown rat and, 4) the Polynesian rat.

Of the 4, the 2 that are the most common nuisance amongst homeowners are the Norway and Roof rats.

The roof rat is a medium sized rat approximately 5 to 7 inches and its tail is always longer than its head and body combined. The Norway rat is 8 to 10 inches long and its tail is always shorter than its head and body combined. These rats are nocturnal and tend to develop habitual behavior patterns. They have a keen sense of smell and hearing and a fair sense of sight. They are also excellent climbers and swimmers.

Rats are most commonly noticed within the structure at night when the homeowner hears them scurrying about the attic.

The first step in controlling rats is to attempt to eliminate their food and water sources. This might entail removing fallen fruits from trees, putting away pet food, etc. Removing both food and water sources may be difficult due to our lush and tropical environment. Keep in mind that rats usually forage within a 160' radius of their nest.

An attempt to eliminate breeding grounds can also be made. This would entail cutting back excessive vegetation and bushes where possible. Also, excessive clutter within a house can provide breeding grounds.

The next step in control of rats is rodent-proofing or exclusion. As a rule of thumb, a rat can squeeze through a hole the size of a quarter. A careful inspection for potential entry points should be made and as many entry points as possible be blocked off.

Rats often enter from areas along the roof. They are excellent climbers and jumpers. All trees overhanging the structure should be cut back. Once a rat gains access to the roof, it can often find an entry point into the structure.

Mechanical control measures such as snap traps or glue boards can also be employed. When laying out these traps keep in mind that rats usually run alongside of structural barriers rather than running around in open areas. This would mean that if you are placing a trap in the attic, you would want to place it against a rafter. Keep in mind that rats are "neo-phobic". That is, they are afraid of new things in their environment. They may initially sense that the trap is new and avoid it for a few days before they get accustom to it.

Lastly we recommend use of rodenticides on the exterior of the structure to help minimize the population. Rodenticides should be placed in an appropriate sealed and secured bait station to prevent children and other small animals from access. As with any pesticide always follow the label directions.

Rats are highly adaptive and thus a continuing control program may be necessary.