[Rodent Control Issue] Up on the Roof

Roof rats may be smaller than Norway rats, but they can cause major damage if steps aren’t taken to prevent an invasion. In addition to consuming and contaminating food and other products, roof rats will chew through wires and create fire hazards; tear up insulation and use it for nesting material; gnaw through plastic and lead water pipes; make holes in walls; and cause other structural damage, which may also lead to other pest problems.

Roof rats also are considered a public health pest because of their ability to transmit diseases. Preferring warm weather and coastal areas, roof rats are found typically in America along the lower half of the East Coast and throughout the Gulf Coast states and into Arkansas. They also exist along the Pacific Coast and on the Hawaiian Islands, but they can easily be shipped to other areas outside of their normal range.

HIGH-RISE DWELLERS. While similar to the Norway rat, roof rats are more aerial in nature and prefer to live in elevated areas, such as trees or rafters. They are agile climbers that can be seen traveling through trees and along vines, wires, rafters and rooftops, especially at night. They’ll frequently enter buildings through the roof or access points via trees or overhead utility lines.

Recognizing their aerial nature is important when deciding on a program to control roof rats because traditional, ground-level baiting or trapping will intercept very few of them. Trapping and control methods must be concentrated at higher levels, such as ceilings, rafters and roofs.

CURTAILING AN INVASION. So how can you protect your customers’ homes or businesses? Effective methods of roof rat control include exclusion, habitat modification, trapping and rodenticides. While the use of snap traps, glueboard traps and rodenticides can provide successful short-term control of an existing roof rat problem, exclusion and habitat modification are more effective at providing long-term control of a roof rat infestation.

Exclusion: Some tips for keeping roof rats out of structures include:

• Sealing all possible entry points 1/2-inch wide or greater, especially near overhead utility lines.
• Repairing any broken or torn screens.
• Covering exhaust fans and vents with a heavy wire screen.
• Using rat guards to prevent them from climbing trees and walls.
• Putting rat guards on overhead utility lines.

Habitat Modification: The following steps can be implemented to modify an area to make it less attractive to roof rats:

• Keep all trees, bushes and vines trimmed back at least four feet from the structure.
• Clean up debris and food around the site, especially on the roof.
• If there are fruit trees on the property, pick the fruit as soon as it is ripe and don’t let fallen fruit lay on the ground, as it will serve as a strong attractant to roof rats (and other pests).

CONCLUSION. If roof rats are threatening to invade your customers’ homes or businesses, develop a plan of action before they wreak havoc and cause costly damage.

The author is technical director, Gregory Pest Prevention, Greenville, S.C.