Invasive Species in the United States: The Big List of Invasive Animals

A closely connected and globalized world can sometimes bring benefits to a local ecosystem, but it also causes a lot of damage. One of the worst phenomena is the spread of invasive species. According to the United States Department of Agriculture, an invasive species can be defined in two main ways: it is foreign or non-native to the ecosystem it inhabits, and it also causes significant damage to the local ecosystem. Some invasive animals are spread intentionally (for example, in an effort to control other pests) and some are spread completely by accident. Climate change is also driving the spread of species to new habitats. The list will be the top 10 worst invasive species in the United States. Each animal will be judged on the extent of its spread and the damage it has caused.

#10: Asian Giant Hornet

Coming from the East Russia, China, Korea, and South Asia, this species is also known as the “slayer hornet”. While the name may be a bit of an exaggeration, the hornet is responsible for killing dozens of people each year; they tend to sting multiple times with their highly poisonous venom. Their effect on the local ecosystem is also quite destructive and bad: they are responsible for crowding out and exterminating other bee and wasp hives. The giant hornet can be recognized by its size alone: ​​it is the largest hornet species in the world. the first known North American sightings took place in the state Washington and the Canadian province of British Columbia in 2019. People are trying to stop its spread before the Asian Giant Hornet becomes an established species.

You can read more about the Asian giant hornet here.

#9: Burmese Python

A resident of Southeast Asia, the Burmese python was imported to the United States as part of the international exotic pet trade. Irresponsible pet management, whether through intentional or unintentional release, has been responsible for this species’ escape into the wild. Established populations were first reported around the Florida area in 2000. Since then, it has caused significant damage to the local ecosystem by either directly preying on native species (such as the highly endangered Key Largo timber rat) or by competing with native species for resources (such as the endangered indigo snake). Even common animals like deer, raccoons, bobcats, and rabbits have refused.

You can read more about the Burmese python here.

#8: Northern Snakehead

The northern snakehead is a large freshwater fish, anywhere from 3 to 5 feet in length, with an elongated body and a snake-like head. Derived from China, Russia, North Korea, and South Korea, this voracious species can easily double its population in about 15 months by killing and consuming other local freshwater animals. The snake’s head bears a superficial resemblance to the native bow fin by North America, but the two species are not actually closely related. The snakehead can be recognized by the large scales on the head, while the bowfin has a bony plate. Snakeheads also have a much longer anal fin and much more pronounced spots along the body.

Read more about the differences between bowfins and snakeheads here.

#7: Spotted Lantern Fly

an adult spotted lanternfly is characterized by pink-grey forewings and red hindwings, both covered with numerous black spots and stripes. Although sometimes mistakenly confused with a moth when its wings are outstretched, the spotted lanternfly is actually more closely related to grasshoppers and grasshoppers. It comes from parts of China, India, and Vietnam, where the primary host plant was the tree of heaven. The lanternfly was first discovered in Pennsylvania around 2014, but may have arrived about two or three years earlier. It can damage a wide variety of different plants and crops, including maples, walnuts, willows, grapes and apples. Signs of the lantern fly may include moldy or infested plants, visible damage and oozing, or a buildup of sticky honeydew. Quarantines have been put in place in several states to prevent the lanternfly from spreading on transported wood and other equipment.

Read more about the spotted lanternfly here.

#6: European starling

This small, unassuming bird, characterized by glossy black plumage and a metallic sheen, is in fact one of the most successful and destructive invasive animals in the world. Huge flocks of European starlings steal nesting sites from local birds, bully and take food from larger animals, causing about $800 million in agricultural damage each year. This species is common everywhere Europe and migrates south for the winter. Since its introduction to the United States in the late 1800s (a contentious story claims Shakespearean enthusiasts attempted to release every type of bird mentioned in the Bard’s works), this species has grown to a population of approximately 200 million. Every year, about four million people are classified as nuisances by the Agriculture Department and subsequently killed.

#5: Wild pigs

The wild boars are not a unique species; instead, these are domestic pigs that escaped or were released back into the wild and formed a new population. It’s easy to forget that pigs are not native to America. They were domesticated in Eurasia and transferred sometime in the 16th century to provide food for the settlers. Millions of pigs grown every year in the United States, so potential escape options abound. Due to their rooting behaviour, pigs can cause considerable damage to crops and native flora. They can also transmit diseases, accidentally collide with vehicles and sometimes even attack people. Some parts of the country have programs to hunt feral pigs.

You can read more about pigs here.

#4: Asian Tiger Mosquito

This species is characterized by its black exoskeleton with white bands around its body. Although it originally came from tropical Southeast Asia, it accidentally arrived in the United States at some point in the late 1800s, hidden among tire imports. With its ability to survive the winter by hibernation for months it spread surprisingly far north, competing with and even displacing some native mosquito species. It is also highly effective in transmitting numerous diseases, including yellow fever, dengue fever, West Nile virus, and more. Climate change can make disease transmission worse. As the cold northern parts of the country begin to warm, the Asian tiger mosquito may become more active year-round.

#3: House cats

The cute and fluffy house cat may look unassuming, but in fact it is one of the most destructive invasive animals in the country. It has a similar historical trajectory to the wild boars: domesticated in Eurasia (from a Middle Eastern wildcat), transferred to the Americas with European settlers, and then sometimes left to roam in the wild. Each year, domestic cats are responsible for approximately one billion bird deaths and six billion deaths from smaller fauna. They also transmit diseases to other wildlife. Keeping your cat indoors is the most effective way to prevent this.

You can read more about domestic cats here.

#2: Zebra mussel

The zebra mussel is a small clam, no more than 2 inches in size, with a D-shaped shell that allows it to sit flat against a solid surface. Originating from the Caspian and Black Sea regions of southern Russia and Ukraine, the zebra mussel was brought to the US as a stowaway in ships’ ballast water (providing stability and maneuvering when no cargo is present). It was first discovered in 1988 at Lake St. Clair and then spread to the Great Lakes, Lake Travis, and the Hudson River.

The microscopic larvae spread very quickly to colonize new areas, but they have to take a boat ride to get upstream, making good quarantine efforts critical. Due to their rapid reproduction rate, they can easily produce more than other freshwater animals and compete for natural resources such as plankton. They also tend to cling to native mussel species as they would a dock or boat with their root-like ‘byssal threads’. This prevents the other mussels from moving. Once established in a new habitat, they are nearly impossible to remove.

Read more about the zebra mussel here.

#1: Emerald Ash Borer

Dressed in a beautiful green exoskeleton, the emerald ash borer is a member of the jewel beetle family. Though completely harmless in its native habitat in northeastern Asia, it quickly spread across North America and Europe, devastating native ash trees: perhaps tens of millions of trees in 30 states have been destroyed and numbers are growing. It was first identified in southeastern Michigan in 2002 perhaps accidentally transferred into wooden packaging material. Signs of its presence include yellow, sparse or wilted foliage with D-shaped beetle exit holes. States have tried to enforce quarantine on timber shipments to curb its spread, but this has proved difficult. Climate change can exacerbate these effects.

Next one: Where do butterflies live?