Wildlife Damage Management, Internet Center for


Date of this Version

July 1994


The Polynesian rat (Rattus exulans) is smaller than either the Norway rat (R. norvegicus) or the roof rat (R. rattus). Polynesian rats have slender bodies, pointed snouts, large ears, and relatively small, delicate feet. A ruddy brown back contrasts with a whitish belly. Mature individuals are 4.5 to 6 inches long (11.5 to 15.0 cm) from the tip of the nose to the base of the tail and weigh 1.5 to 3 ounces (40 to 80 g). The tail has prominent fine scaly rings and is about the same length as the head and body. Female Polynesian rats have 8 nipples, compared to 10 and 12 nipples normally found on roof rats and Norway rats, respectively.

Polynesian rats are native to Southeast Asia but have dispersed with humans across the central and western Pacific. Today, these rodents inhabit almost every Pacific island within 30o of the equator. They occur from the Asiatic mainland south to New Guinea and New Zealand, and east to the Hawaiian Islands and Easter Island. Polynesian rats accompanied early Polynesian immigrants to Hawaii and today occur on every major island of the archipelago. The Polynesian rat is not present in the mainland United States.

Exclusion: Not practical for Hawaiian sugarcane fields.
Cultural Methods: Synchronize planting and harvesting of large blocks of fields. Eliminate or modify noncrop vegetation adjacent to sugarcane fields. Develop potential resistant sugarcane varieties.
Repellents: None are registered.
Toxicants: Zinc phosphide.
Fumigants: Not practical in and around sugarcane fields.
Trapping: Not practical in and around sugarcane fields.
Shooting: Not practical.
Biological Control: Not effective.