Definition

A rat is any of various long-tailed rodents resembling mice but larger, especially one of the genus Rattus.

Etymology. O.E. ræt. Similar words in Celtic (Gael. radan), Romance (It. ratto, Sp. rata, Fr. rat) and Gmc. (M.L.G. rotte, Ger. ratte) languages, but connection is uncertain and origin unknown. Perhaps from V.L. *rattus, but Weekley thinks this is of Gmc. origin, "the animal having come from the East with the race-migrations" and the word passing thence to the Romanic languages. American Heritage and Tucker connect O.E. ræt to L. rodere and thus PIE *red- "to scrape, scratch, gnaw," source of rodent (q.v.). Klein says there is no connection and suggests a possible cognate in Gk. rhine "file, rasp." Weekley connects them with a question mark and Barnhart writes, "the relationship to each other of the Germanic, Romance, and Celtic words for rat is uncertain." OED says "probable" the rat word spread from Germanic to Romance, but takes no position on ultimate origin. M.E. common form was ratton, from augmented O.Fr. form raton. Sense of "one who abandons his associates" (1629) is from belief that rats leave a ship about to sink or a house about to fall and led to meaning "traitor, informant" (1902; verb 1910). Interjection rats is Amer.Eng., 1886. To smell a rat is c.1550. Rat-race "competitive struggle" is 1939. Ratsbane (1523) is arsenic. Rat fink is teen slang from 1963. Rathole in fig. sense of "nasty, messy place" first attested 1812. _____-rat, "person who frequents _____" (in earliest ref. dock-rat) is from 1864. Rat-pack "juvenile gang" is from 1951.

Discussion

Rats as Plant Pests in Hawaii

Rats

Reproductively, the rat is very prolific. The young rat is sexually mature at 4 months and reproductive potential is continuous until death. Rat behavior is influenced by thirst, hunger, sex, maternal instinct, and curiosity. Rats cannot go without water for more than 48 hours or without food for more than four days. Thirsty or hungry rats become desperate and are therefore easier to control because they are less wary. Rats are nocturnal and tend to become habitual. They have a keen sense of smell and hearing, and a fair sense of sight with ability to see in the dark.

Roof rat

(Rattus rattus)

A medium to large rat, body 5 to 7 inches long. Tail slender and always longer than head and body combined. Body color varies from grey to jet black; underside grey, grey-white, or white. Nose sharply pointed, large eyes, large, thin ears; in female, five pairs of nipples. Expert climber and wire scaler; frequents cane fields, macadamia nut, coffee, papaya, and banana groves; nests in attics of buildings, trees, banana bunches, and abandoned burrows of Norway rats.

Polynesian rat (Rattus exulans)

Comparatively small in size, weighs 2 to 3 ounces, and measures 4 to 5 inches long. The tail is as long as or slightly longer than head and body combined; bristles along the tail give the appearance of faint, narrow rings. The body color is cinnamon-brown to cinnamon-buff to grey with stiff black guard hairs on back and sides; the underside is light buff or grey. The nose is roundly pointed, ears rather short, eyes medium size, hind feet dark on underside. Females have four pairs of nipples. A field rat, rarely found near buildings in Hawaii. It nests in burrows, gulches, rock piles, rock walls, wastelands, fields, and embankments. It causes great damage to sugarcane, pineapple, macadamia nuts, coconuts, coffee, and other fruit and vegetable crops.

Hosts

Rats are omnivorous. Among agricultural plants and commodities they have a wide host range, including fruits, nuts and plant tissues. Rats are also predators.

Damage

Rats can damage can kill or severely injure coffee verticals.

Management

cultural

Remove access to food, water, or shelter, or limit rat accessibility; traps; trim overhanging trees away from coffee plants; cats and dogs.

chemical

(Hawaii)

Rodenticides are the most effective means of controlling large and small rodent populations. Strict safety precautions should be used in the preparation, broadcast, or placement and disposal of poison baits for rodents.

Literature cited

Brennan, Barry M. Rodents and rodent control in Hawaii. 1980. Research Extension Series 002. University of Hawaii at Manoa, College of tropical Agriculture and Human Resources, 630 US ISSN 0271-9916, http://pestworld.stjohn.hawaii.edu/studypackets/rodents.html

Rat feeding injury to a fruit of banana (Musa sp.).	Vertical branches of coffee (Coffea arabica) severed by the feeding of rats.	Rat feeding injury to the stem and pith of a vertical branch of a coffee (Coffea arabica) plant.	Rat feeding damage to an unripe noni (Morinda citrifolia) fruit.
Rat feeding injury to a kava (Piper methysticum) stem.

Rats as Plant Pests in Hawaii
Rats	Reproductively, the rat is very prolific. The young rat is sexually mature at 4 months and reproductive potential is continuous until death. Rat behavior is influenced by thirst, hunger, sex, maternal instinct, and curiosity. Rats cannot go without water for more than 48 hours or without food for more than four days. Thirsty or hungry rats become desperate and are therefore easier to control because they are less wary. Rats are nocturnal and tend to become habitual. They have a keen sense of smell and hearing, and a fair sense of sight with ability to see in the dark.
Roof rat *(Rattus rattus)*	A medium to large rat, body 5 to 7 inches long. Tail slender and always longer than head and body combined. Body color varies from grey to jet black; underside grey, grey-white, or white. Nose sharply pointed, large eyes, large, thin ears; in female, five pairs of nipples. Expert climber and wire scaler; frequents cane fields, macadamia nut, coffee, papaya, and banana groves; nests in attics of buildings, trees, banana bunches, and abandoned burrows of Norway rats.
*Polynesian rat (Rattus exulans)*	Comparatively small in size, weighs 2 to 3 ounces, and measures 4 to 5 inches long. The tail is as long as or slightly longer than head and body combined; bristles along the tail give the appearance of faint, narrow rings. The body color is cinnamon-brown to cinnamon-buff to grey with stiff black guard hairs on back and sides; the underside is light buff or grey. The nose is roundly pointed, ears rather short, eyes medium size, hind feet dark on underside. Females have four pairs of nipples. A field rat, rarely found near buildings in Hawaii. It nests in burrows, gulches, rock piles, rock walls, wastelands, fields, and embankments. It causes great damage to sugarcane, pineapple, macadamia nuts, coconuts, coffee, and other fruit and vegetable crops.
Hosts	Rats are omnivorous. Among agricultural plants and commodities they have a wide host range, including fruits, nuts and plant tissues. Rats are also predators.
Damage	Rats can damage can kill or severely injure coffee verticals.
Management
cultural	Remove access to food, water, or shelter, or limit rat accessibility; traps; trim overhanging trees away from coffee plants; cats and dogs.
chemical (Hawaii)	Rodenticides are the most effective means of controlling large and small rodent populations. Strict safety precautions should be used in the preparation, broadcast, or placement and disposal of poison baits for rodents.