Destructive Invasive Species That Could Take Over the World
You might be familiar with the term "invasive species," but you probably don’t know just how much damage these invaders can cause. According to the National Wildlife Federation, roughly 42% of endangered or threatened species are imperiled because of invasive species.
Without any natural predators or counterbalances to keep them in check, most interlopers thrive, destroying trees, reefs and native animal populations. Read on to learn about the most shocking invasive species that are continuing to plague our ecosystems.
The world’s largest toad was introduced to Australia in 1935 to combat the growing cane beetle population. Initially, 3,000 toads were released, but, without any natural threats to curb their growth, that number now exceeds 200 million.
Brought to the Americas in the 1500s, feral swine are descended from run-of-the-mill farm pigs. Found in roughly 35 states, these 5 million pigs cause $1.5 billion in damages annually. Even if you don’t have 30 to 50 feral hogs in your yard, these pigs can still cause a lot of destruction.
Among the largest snakes on Earth, Burmese pythons can reach lengths of 23 feet and weigh in at 200 pounds. In 1992, Hurricane Andrew ripped through a python-breeding facility and zoo, allowing Burmese pythons to escape into the Florida Everglades.
In 1859, a wealthy estate owner released 24 specimens in Victoria, Australia, so he could hunt them for sport. With ample food sources and no natural predators, these fast-breeding rabbits quickly took over the eastern part of the country.
Native to East Africa, the Nile crocodile hasn’t been seen in the U.S. before — well, until now. Researchers have spotted at least four of these crocs in Florida. Unlike American crocodiles and alligators, these crocs can grow up to 16 feet long and weigh up to 1,600 pounds.
The silver, bighead, grass and black carp are collectively called Asian carp. These fish were imported to the United States in the 1970s to filter pond water in Arkansas. However, flooding enabled the carp to spread to the Illinois River and other waterways.
The monk parakeet was popular in the "exotic" pet trade of the 1960s, which is how this species arrived in Florida. By 1968, 16,000 birds had been imported to the U.S., with escapees traveling as far north as New York and as far west as Oregon.
Brown Marmorated Stink Bug
The brown marmorated stink bug (BMSB) is native to Japan, China, South Korea and several other Asian countries. In the mid-1990s, the BMSBs appeared in Pennsylvania, though it is unclear exactly how they ended up in the U.S.
Native to Brazil, Portugal, Mexico and several surrounding islands, the green (or American) iguana is one of Florida’s most destructive invasive species. Surprisingly, iguanas don’t really compete with other native lizards for food. Instead, they wreak havoc on lawns and gardens.
About 50 species are part of the genus Ligustrum, so "privet" refers to quite a few different shrubs and trees. Able to adapt with ease, privet often outcompetes and displaces native vegetation. The ornamental plant was first brought to the United States from Asia in the 1700s.
Cats may not come to mind when you think of an invasive species. However, homeless cats lead rough lives. Abandoned and abused, they form colonies in cities and on islands, where the adept hunters have a huge impact on the place’s biodiversity.
These bivalves were transported across the Atlantic Ocean in the ballast water of ships. In the 1980s, they started to cause huge problems in the Great Lakes. Now, by hitching rides on the bottoms of boats, zebra mussels have spread to at least 29 states.
Little Fire Ants
Not to be confused with Hawaii’s native tropical fire ant, little fire ants have infested the state’s Big Island. Due to their habit of building nests in potted plants, trees and shippable produce — instead of building mounds — they were accidentally imported.
European Green Crab
Native to — you guessed it — Europe, these crustaceans were first introduced to the East Coast of the United States in 1817, possibly through ballast water. By 1989, European green crabs were spotted in San Francisco Bay, and the creatures have since spread both north and south.
Burma reed is a tall grass native to subtropical Asia, but it has become a huge issue in southern Florida. In the Everglades, this fast-growing plant heavily shades the understory, killing the sunless flora.
Native to its namesake in southern Africa, the Mozambique tilapia is popular in the aquaculture industry. In many parts of the world, it escaped from fish farms into native water sources; in other instances, the tilapia was purposely released to temper mosquito populations.
Mongooses are native to India and parts of Southeast Asia, but they were introduced to Hawaii, Jamaica and other nations in the 1800s, during the rise of the sugar cane industry. The goal was simple: Mongooses would feed on the rats that were gobbling up the sugar cane.
Hybrid Tumbleweed (Salsola Ryanii)
A tumbleweed is the above-ground part of a plant that has matured, dried and detached from its roots, tumbling to disperse seeds. Hybrid tumbleweeds — formed by plants native to Australia, Africa and Europe — have invaded California’s Central Valley since the early 2000s.
Native to the Indo-Pacific, the carnivorous lionfish is now an invasive species that has infiltrated the Atlantic Ocean. Lionfish are a top predator, and their introduction to a whole new ocean has had lasting effects on the delicate ecosystems of coral reefs.
Brown Tree Snake
Native to Australia, Indonesia and Papua New Guinea, the brown tree snake — probably a cargo stowaway — was accidentally introduced to Guam in the 1950s. With an abundance of prey and few natural predators (save the occasional feral pig or mangrove monitor), the snakes have taken over.
This multi-stemmed, thorny shrub can grow up to 15 feet. As you might imagine, that means multiflora rose plants form impenetrable thickets in forests and fields. First introduced to North America in 1866 as rootstock for ornamental roses, the multiflora rose is native to parts of Asia.
Weighing upwards of 100 pounds, the capybara is the world’s largest rodent. Native to South America, it has set up shop in Florida for at least the last 15 years. It’s estimated that roughly 50 of these rodents call the Sunshine State home, but that number is expected to climb rapidly.
Known commonly as the killer bee, the Africanized bee is a hybrid species first introduced to Brazil in 1956 to increase honey production. In 1957, however, 26 swarms escaped quarantine, and the bee has spread throughout the Americas, arriving in Texas in 1990.
The spiny waterflea is a microscopic animal — or zooplankton — that thrives in open water. Originally, this zooplankton called the waters off Europe and Asia home, but it was accidentally carried over to the Great Lakes in the United States through ships’ ballast water.
Known as the European or common starling, this bird seems harmless, but it has been labeled a pest in some countries. The starling was introduced to places like Australia and New Zealand to feed on insects devastating local crops, but their journey to North America was a bit different.
This freshwater predatory fish became known as a popular food fish. Because of that tie to aquaculture, the fish accidentally escaped into non-native waters. And it has become your standard food hog.
Emerald Ash Borer
Native to northeastern Asia, these beetles have come to devastate North America. As the name implies, the insects bore into ash trees to lay their eggs. The ash trees have no defense against the beetles and, once chosen, are destroyed.
Kudzu, derived from the Japanese name for the East Asian arrowroot plant, is a vine native to eastern Asia, Southeast Asia and various Pacific islands. Known for climbing and coiling, these vines often kill trees and shrubs through shade — heavy amounts of shade.
Giant African Snail
These large land snails are considered pests on many continents due to the ways they attack agriculture and spread disease. Not only do these snails transmit diseases to crops, they can also spread the parasitic nematode that causes meningitis to humans.
These invasive crustaceans are native to the Ohio River but have spread to several other states and into Canada. Because a female crayfish can carry fertilized eggs, the release of just one crayfish can be devastating.