America’s 17 Most Invasive Species

Nature is all about balance. But when certain species take root in a given environment without any natural predators to keep them in check, they can rapidly become invasive. These species will then grow rampantly. As a result, they may cause significant environmental change and disruption to local habitats.

Some species have entered our environment and need immediate action. However, due to the overwhelming challenges they present, some have ceased making attempts to eradicate them. Here are some of the most invasive species that are taking America by storm.

Nutria

• Origin: South America 
• Other names: Coypu, Swamp Rat
• Destructive power: Habitat destruction, rapid reproduction

The nutria or coypu is a hefty semi-aquatic rodent that originates from South America. Brought over to North America during the fur trade era, their numbers have escalated quickly. This led to severe destruction of wetlands as they burrow and feed on vegetation voraciously.

Feral Hogs

• Origin: Europe, Asia
• Other names: Wild boar, wild hog
• Destructive power: Crop destruction, landscape alterations

Originally from Europe and Asia, feral hogs are now causing havoc across the United States. These animals are highly adaptable. They also reproduce quickly and are known for their destructive feeding habits that damage crops, forest areas, and wildlife habitats. 

Domestic Cat

• Origin: Near East
• Other names: Housecat, alley cat
• Destructive power: Kill small animals and native birds

While beloved as household pets, the domestic cat has an inauspicious reputation in the wild. Originating in the Near East, these adept hunters were introduced to America by European settlers. The issue lies in their prolific hunting prowess, which disrupts local ecosystems as they prey on native species, especially birds. 

European Starling

• Origin: Europe 
• Other names: Common starling, English starling 
• Destructive power: They impact native bird populations and cause significant agricultural damage

Introduced to America in the late 19th century for Shakespearean nostalgia, these birds rapidly multiplied, now numbering in the hundreds of millions. The starlings are notorious for their aggressive behavior. They are often outcompeting native species for resources and nesting space, which can lead to a decline in native bird populations. They also hurt agriculture by destroying crops and spreading diseases. 

Cane Toads

• Origin: Central and South America
• Other names: Giant toad, marine toad
• Destructive power: Mass breeding and consumption, toxic to native predators and pets

Found initially in Central and South America, cane toads were initially brought in to control sugarcane pests in the agricultural terrains of Florida during the early 1930s. The toad’s big appetite and lack of predators in America caused it to multiply quickly. They are fast breeders and extreme omnivores, strikingly reducing local biodiversity by out-competing native fauna for food and habitat. They can also kill predators with their highly poisonous secretion, which greatly affects the food chain.

Asian Carp

• Origin: China
• Other names: Bighead, silver, grass, and black carp
• Destructive power: Rapid reproduction, outstrips resources in marine ecosystems

Asian carp is the collective name for four species of carp originally from China. Introduced in the 1970s to clean southern fish farms and sewage treatment ponds, these aquatic invaders significantly disrupt ecosystems by out-competing native fish species for food and habitat. Their high-speed growth and reproduction rate make them a menace that contributes to biodiversity loss. 

Lionfish

• Origin: Indo-Pacific
• Other Names: Dragonfish, scorpionfish
• Destructive power: Consumes native species and disrupts ecological balance

Striking with sharp, venomous spines and stunning with vibrant colors, the lionfish is not a creature easily ignored. Originally from the Indo-Pacific region, this species found its way to American waters through the aquarium trade. Lionfish gobble up native species and eggs, and predators shy away from their quilled defense. Also, its unchecked appetite alters ecosystems and puts fisheries’ stocks at risk.

Zebra Mussels

• Origin: Eastern Europe
• Other names: Striped invaders
• Destructive power: Species displacement, infrastructure damage, biodiversity loss

The Zebra Mussel is a small yet destructive invader that reproduces so rapidly that it has been difficult to manage or control. Hitching a ride on ships from Eastern Europe to the United States in the late 20th century, they have since colonized many American freshwater ecosystems. Their invasive behavior forms dense colonies that suffocate native mussels. They can also clog up infrastructures like water treatment and power plants.

Rusty Crayfish

• Origin: North America, especially the Ohio River basin
• Other names: Rusties
• Destructive power: Alter habitats by eating large amounts of vegetation and displace native species

These resilient crustaceans were initially kept in aquariums, but they were accidentally released into the wild. They have a hearty appetite and indiscriminately consume aquatic plants, diminishing the habitat for other species, and lowering the overall diversity of the ecosystem. Their aggressive nature and rapid reproduction pushed out native species and quickly overtook new environments.

Brown Marmorated Stink Bug

• Origin: East Asia
• Other names: Yellow-brown stink bug, East-Asian stink bug
• Destructive power: High, particularly to agricultural crops

Making its way from Asia, the Brown Marmorated Stink Bug has become a dominant invasive species causing calamity in the U.S. They’re known for their infamous ‘stink’, and multiply rapidly with few natural predators. They made their way via trade routes, unintentionally introduced, and since their arrival, they’ve been a serious menace. They are also damaging to agriculture. They cause harm to farmers growing fruits, vegetables, and ornamentals, which they feed on relentlessly.

Gypsy Moth

• Origin: Europe
• Other names: European gypsy moth
• Destructive power: Destroys forests by defoliating host trees, posing a threat to the ecosystem and causing economic losses

Nicknamed the “Tree-devouring Devil,” gypsy moths have imposed their reign of terror upon American forests for more than a century. A French scientist brought these to America in 1869. He wanted to start a silk business but they accidentally got loose. These insects are notorious for their huge appetite, consuming over 500 types of trees and shrubs and leaving behind destruction. They can adapt to diverse climates and resist pesticides, making eradication efforts a challenge. 

Emerald Ash Borer

• Origin: Eastern Asia
• Other Names: Green menace
• Destructive Power: Destruction of Ash Trees En masse, causing considerable damage to forests, public lands, and urban landscapes

Emerald Ash Borer, a vibrant metallic-green beetle, holds an infamous reputation as one of the most terrifyingly effective tree killers in America. Originally from Asia, the beetle found its way to the U.S. via wooden packing materials. The larvae of these pests feast on the bark of ash trees, disrupting their ability to transport water and nutrients, leading to their death. They have decimated millions of ash trees across America, causing substantial economic and ecological damage. 

Africanized Honey Bee

• Origin: South America
• Other names: Killer bee, African killer bee
• Destructive power: Aggressive attack behavior, takeover local bee populations, and disruption of ecological chain

The Africanized Honey Bee, colloquially known as the “Killer Bee,” packs an aggressive disposition that stretches far beyond its puny size. Originating from South America, they snuck into the United States through Texas in 1990. Their invasive nature lies in their quick reproduction, aggressive behavior, and tendency to take over local bee populations’ habitat. These harmful insects create problems by taking over native bees’ homes and beating them to food, which messes up their natural behavior.

Asian Citrus Psyllid

• Origin: Asian continent
• Other names: Asian citrus psylla, citrus psyllid
• Destructive Power: Transmits citrus greening disease causing severe damage to the citrus industry

No bigger than a grain of rice, this citrus plant-loving pest has been wreaking havoc all over America. Hailing from Asia, it hitched a ride on plant material to find a new home in the U.S. It can transmit a deadly plant disease—citrus greening, leading to significant damage to the citrus industry.

Burmese Python

• Origin: Southeast Asia
• Other names: Asian Rock Python
• Destructive power: Rapid breeding, no natural predators

The Burmese Python is one of the largest snakes globally that is causing an ecological disturbance as an invasive predator within the Florida Everglades. Native to Southeast Asia, these pythons ended up in America, primarily through the exotic pet trade. They pose a significant problem due to rapid breeding and their lack of natural predators, which lead to a severe decline in native species. 

Kudzu Bug

• Origin: Asia
• Other names: Globular stink bug
• Destructive power: Damage to soybean crops and disruption of local ecosystem

The Kudzu bug, also known as the globular stink bug, hails from Asia but has found a foothold in the southern United States, specifically in farmlands. These pea-sized bugs arrived on American shores via international cargo and rapidly adapted to the environment, feasting on the invasive kudzu plant, but also wreaking havoc on soybeans, a major agricultural crop. They pierce the plant and drink its sap, leading to wilting, stunted growth, and reduced yield.

Chilli Thrips

• Origin: Southeast Asia
• Other Names: Yellow tea thrips
• Destructive Power: Significant damage to a wide variety of crops, reducing both the aesthetic and market value

These minuscule creatures, just about 1 mm in length, can cause significant damage to a wide variety of field, fruit, ornamental, and vegetable crops. They creep onto U.S. soils through international trade and quickly reproduce to form large populations. The thrips feed on plant cells, causing a bronzing effect that reduces both the aesthetic and market value of produce.