The U.S. Fish and Wildlife Service reports that there are approximately 4,300 invasive, non-native species in the United States. These species have a negative effect on both the environment and the economy. From cute to just plain creepy, these animals wreak havoc in their new environments, costing U.S. taxpayers billions of dollars. According to the National Invasive Species Council, invasive species cost the United States over $138 billion dollars a year.

In Pictures: 10 Ways To Prepare For Nature's Worst

The nutria, or Myocastor coypu, is a rat-like, semi-aquatic rodent that was imported to the Louisiana in 1930 for its valuable fur. Once demand for the nutria's fur declined, the nutria population exploded. These pesky rodents are destroying aquatic vegetation, overrunning and eroding wetlands, and pushing out native animals.

Nutria damage is so severe in Louisiana that the Louisiana Department of Wildlife and Fisheries placed a bounty on the pesky rodent paying hunters $5 for each tail. The Department of Wildlife and Fisheries estimates that 20,300 acres of wetlands are impacted by nutrias. These bounties have cost the state of Louisiana over $9.3 million in incentive payments since 2002. The nutria control program will cost the state a total of $65.7 million dollars.

Louisiana is not the only state suffering from the destructive impact of coypu. Nutrias are causing problems in Oregon, Washington, Virginia and Maryland. The National Wildlife Federation blames the nutria for the destruction of 500 to 1,000 acres a year on Maryland's Blackwater National Wildlife Refuge. (Learn more about the relationship between the environment and the market. Read Save The Earth: Become A Capitalist.)

Feral Pigs
Feral pigs have become a big problem for residents in the southern region of the United States. The feral pig was originally introduced to the south as a source of food but today has become a nuisance. The Federal Department of Agriculture estimates that over four million feral pigs have spread to 37 different states over the past few years. According to the New York Times, feral hogs "cause an estimated $800 million in property damage every year, or $200 a hog."

These hogs trample fences and destroy property. They feed upon crops and kill young livestock. They disrupt the ecosystem by digging up the earth looking for food. Feral pigs are known carriers of diseases including brucellosis, encephalitis, pseudorabies, leptospirosis and foot-and-mouth disease. (Learn how to protect against property damage; read The Importance Of Property Insurance.)

Northern Snakehead
The northern snakehead fish is a dangerous predator that has become a problem in the U.S. in recent years. Snakeheads are native to Asia and Africa but after having been released from fish markets, they can now be found in the United States. The northern snakehead is an invasive species of fish that can survive on land for up to four days. Ninety-percent of the northern snakeheads' diet consists of other fish, according to National Geographic.

Snakeheads eat anything that will fit in their mouths including fish, birds, frogs and small mammals. Snakeheads have the potential to alter ecosystems and wipe out any fish that it comes into contact with. The U.S. Fish and Wildlife Service estimates that just $85,000 worth of snakeheads have already done millions of dollars in damage.

Asian Tiger Mosquitoes
Asian tiger mosquitoes migrated to the United States accidentally from Japan in 1985. The pesky mosquitoes were imported inside used Japanese tires. These bloodsucking pests can breed where other mosquitoes cannot (tires, cans, dog dishes, plastic bags, flower vases). They can cause skin problems, allergic reactions and are known carriers of the West Nile virus, dengue fever and encephalitis. The Asian tiger mosquito infests over 30 U.S. states and that number continues to grow.

Trying to get a handle on the mosquito population has resulted in increased spending for mosquito control programs. According to study conducted at the University of Georgia, the state of New York spent more than $30 million dollars to fight off these disease-carrying mosquitoes. The USDA gave Rutgers University $3.8 million in 2007 to develop techniques to suppress the Asian tiger mosquito.

Cane Toad
Cane toads were introduced to the island of Hawaii to help control agricultural pests that feed on sugar cane, and were accidentally released in Florida in 1955. Cane toads are known to dwell in ponds, gardens, drain pipes, debris and underneath homes. Cane toads are known to eat just about any terrestrial animal and compete with native species for food. They will eat insects, birds, lizards, snakes, vegetation and other frogs. They have even been known to eat dog and cat food.

The cane toad produces poisonous toxins that it sprays from its glands that have been known to kill dogs, cats, snakes, and lizards. The toxins are hazardous to humans as well causing skin irritation and eye burning. Cane toad control programs have failed worldwide. The Australian government has spent $20 million dollars trying to develop ways to combat cane toads but to no avail.

Indian Mongoose
The small Indian mongoose was introduced to Hawaii and Jamaica in the 1800s to protect sugar cane from the rising rat population that was rapidly destroying crops. The introduction of the Indian mongoose only made things worse. While the mongooses did kill some rats, they preferred killing birds, reptiles and other small mammals. The Indian mongoose is to blame for the presence of many birds, turtles, lizards and rabbits on the endangered species list worldwide.

The mongoose has become a menace, damaging banana and papaya crops and carrying infectious diseases. Mongooses are carriers of leptospirosis and rabies. The Indian mongoose is responsible for approximately $50 million annually in damages.

The Bottom Line
When animals are introduced to a foreign environment they not only have a harmful effect on the ecological system but on the U.S. taxpayer as well. (Learn about the personal financial impact of animals in The Economics Of Pet Ownership.)

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