[9] Although it is still hunted and trapped for its fur in some regions, its destructive burrowing and feeding habits often bring it into conflict with humans, and it is considered an invasive species in the United States.

[11] The genus name Myocastor derives from the two Ancient Greek words μῦς (mûs) 'rat, mouse', and κάστωρ (kástōr) 'beaver'.

To avoid this ambiguity, the name coypu or coipo (derived from Mapudungun) is used in South America, Britain and other parts of Europe.

Three distinguishing features are a white patch on the muzzle, webbed hind feet, and large, bright orange-yellow incisors.

A nutria is often mistaken for a muskrat (Ondatra zibethicus), another widely dispersed, semiaquatic rodent that occupies the same wetland habitats.

Baby nutria are precocial, born fully furred and with open eyes; they can eat vegetation and swim with their parents within hours of birth.

[33] Native to subtropical and temperate South America, its range includes Chile, Argentina, Uruguay, Paraguay and the southern parts of Brazil and Bolivia.

As a result, populations of nutria often contract and even become locally or regionally extinct as in the Scandinavian countries and such US states as Idaho, Montana, and Nebraska during the 1980s.

As of 2024[update], they had spread to the San Francisco Bay Area, where their digging threatened storm levees, and the California Department of Fish and Wildlife had an active eradication program.

[15] According to the Louisiana Department of Wildlife and Fisheries, nutria were also transplanted from Port Arthur, Texas, to the Mississippi River in 1941 and then spread due to a hurricane later that year.

Their creation of "eat-outs", areas where a majority of the above- and below-ground biomass has been removed, produces patches in the environment, which in turn disrupts the habitat for other animals and humans dependent on wetlands and marshes.

[26] Local extinction in their native range due to overharvesting led to the development of nutria fur farms in the late 19th and early 20th centuries.

Nutrias from these farms often escaped, or were deliberately released into the wild to provide a game animal or to remove aquatic vegetation.

[53]: 19–20  In the Chesapeake Bay region in Maryland, where they were introduced in the 1940s, nutria are believed to have destroyed 2,800 to 3,200 hectares (7,000 to 8,000 acres) of marshland in the Blackwater National Wildlife Refuge.

[54] In the United Kingdom, nutria were introduced to East Anglia, for fur, in 1929; many escaped and damaged the drainage works, and a concerted programme by MAFF eradicated them by 1989.

[59] In 2012, the Louisiana Wildlife Federation recognized Marsh Dog with "Business Conservationist of the Year" award for finding a use for this eco-sustainable protein.

[56] As of 2016, however, the meat is used successfully in Moscow restaurant Krasnodar Bistro, as part of the growing Russian localvore movement and as a 'foodie' craze.

"[42] Unlike other common disturbances in marshlands, such as fire and tropical storms, which are a once- or few-times-a-year occurrence, nutria feed year round, so their effects on the marsh are constant.

Fish and Wildlife Service determined wetlands covered only 5% of the land surface of the contiguous 48 United States, but they support 31% of the nation's plant species.

Human users also receive many benefits from wetlands, such as cleaner water, storm surge protection, oil and gas resources (especially on the Gulf Coast), reduced flooding, and chemical and biological waste reduction, to name a few.

[64] In Louisiana, rapid wetland loss occurs due to a variety of reasons; this state loses an estimated area about the size of a football field every hour.

[67] The LDWF stresses that coastal wetland restoration projects will be greatly hindered without effective, sustainable nutria population control.

In addition to direct environmental damage, nutria are the host for a roundworm nematode parasite (Strongyloides myopotami  [d]) that can infect the skin of humans, causing dermatitis similar to strongyloidiasis.

[76] Increased local awareness of viral, bacterial and parasitic transmission from nutria to humans and livestock will be of greater importance as climate change progresses.

After the war in 1950, many nutria were released en masse or escaped, and became one of Japan's worst invasive species, damaging river banks, rice fields and other valuable crops.

[90][91] The first records of nutria invading California dates from the 1940s and 1950s, when the species was found in the agriculture-rich Central Valley and the south coast of the state, but by the 1970s the animals had been extirpated statewide.

State officials are concerned that they will harm infrastructure that sends water to San Joaquin Valley farms and urban areas.

[67] Another program executed by LDWF involves creating a market of nutria meat for human consumption, though it is still trying to gain public notice.

Other potential chemical pesticides would be required by the US Environmental Protection Agency to undergo vigorous testing before being acceptable to use on nutria.

[citation needed] In Louisiana, a claimed environmentally sound solution is the killing of nutria to make dog food treats.