6 weird invasive species wreaking havoc in the US, from self-cloning ticks to 20-pound rodents with orange teeth

Nutria are large, aquatic rodents that resemble a cross between a beaver and an over-sized rat. Like beavers, they have bright orange teeth due to a special enamel that contains iron. The rotund rodents, which notably lack necks, can grow to be two feet long and weigh 20 pounds.

Nutria are native to South America but were brought to the US in the late 1890s as part of the fur trade. According to the USDA, many escaped or were set loose in the 1940s after the fur trade collapsed. The invasive species has now spread to at least 20 states, primarily in Gulf Coast states like Louisiana and Florida.

Nutria cause environmental destruction in part due to their ferocious eating habits. They consume up to 25% of their weight in plants daily with a feeding strategy that involves burrowing, which can destroy soil, disrupt native plants, trigger erosion, and damage infrastructure.

The giant African land snail can grow to be 8 inches long. The species is native to East Africa and is considered one of the most destructive snails in the world.

The invasive species was introduced to Hawaii in 1936 and to the continental US in 1966, according to the USDA. When the snails were found in Florida in the 1960s, the eradication effort cost $1 million and took ten years. However, the snails have recently been discovered in Florida again, for the third time in the state's history.

The snails eat at least 500 different plants and can cause damage to plaster and stucco infrastructure. The snails, which can reproduce 1,200 eggs annually, also carry a parasite that can cause meningitis in humans.

Shovel-headed garden worms, native to Southeast Asia, can grow to be a foot long and have flat bodies with long stripes. They are also known as hammerhead worms, thanks to their flat, spade-like head that resembles a hammerhead shark's.

The worms first arrived in the US in 1891 and can be found in states like Texas, Arkansas, and Georgia. The worms are effective predators, feeding on earthworms, which are essential to maintaining soil health.

"If earthworms were eliminated, then our plants aren't getting the nutrients they need," Ashley Morgan-Olvera, a researcher with the Texas Invasive Species Institute, told Texas Monthly. "This could impact how our yards, our gardens, and our crop fields grow."

Asian longhorned ticks are about the size of a sesame seed and are native to eastern China, Japan, eastern Russia, and Korea. The light brown ticks have been in the US since at least 2010 and have spread to several eastern states, according to the USDA.

The invasive species poses a threat to wildlife and has been found infesting animals like sheep, goats, dogs, cats, horses, deer, and people. They have even killed cattle. In 2021, a farmer in Ohio found three of his cows dead and covered in Asian longhorned ticks.

The ticks can also clone themselves — or reproduce without a male — so a single tick is capable of starting a new population by laying 2,000 eggs.

The emerald ash borer is a tiny beetle native to East Asia that was first detected in the US in 2002. About the size of a grain of rice, the beetle is a stunning, shiny shade of jewel green. Emerald ash borer infestations have been discovered in 36 states.

As a wood-boring pest, the invasive species lays its eggs on the bark of an ash tree. The larvae then carve their way into the tree and feed on its tissues. The boring disrupts the tree's food and water intake, eventually killing it.

Since arriving in the US, emerald ash borers have decimated American ash trees, killing tens of millions across the country. Scientists say it's the most destructive pest ever to plague America's forests.

Pigs, native to Europe and Asia, were brought to the US in the 1500s by early explorers as a source of food. Feral swine in the US today are the same species as pigs found on farms, according to the USDA, and are the descendants of pigs that either escaped or were released. Today, feral pigs can be found throughout the South and in California.

However, "super pigs" bred in Canada may also be invading the US from the north. The super pigs, a cross between a domestic pig and a European wild boar, were bred decades ago to make larger swine. The super pigs grow thick, furry coats, equipping them to survive winters in Canada and the northern US.

The pigs, which grow to well over 600 pounds, prey on native species like frogs, salamanders, and ground-nesting birds like ducks and geese. They also destroy agricultural crops by tearing up the land while rooting around for things like plant roots and insect larvae.

There have been some documented occurrences of the super pigs in North and South Dakota, but the animals have been unable to establish a permanent population — for now.