Cane toads are an example of an intentional species introduction turned invasive

The Burmese pythons in the Florida Everglades and the spotted lanternfly—native to Asia and now found throughout the US—are among the invasive species accidentally introduced and spread by humans.

Nearly all species introduced into a new environment are not invasive

Introduced by zoologist Charles Elton in 1958, the term "invasive species" refers to organisms that are not native to an environment but cause harm after their introduction. Some ecologists argue that terminology such as "native" and "non-native" may only serve to assist in extinction when legislation is limited to protecting "native" organisms.

Benign species can become invasive if introduced into predator-free habitats

Most ecosystems contain organisms that, over many generations, have evolved into a stable balance with one another and their surroundings. In a new environment, a species may no longer be restricted by the limiting factors it is used to, and the native organisms in the area may not adapt quickly enough to the invader to establish a new balance.

While invasive species typically harm ecosystems by outcompeting native organisms for resources, some provide unexpected benefits, including new shelters, nesting habitats, and reduced environmental heat stress.

Poison frogs get their toxins from eating insects and mice

Other animals, including royal ground snakes, are able to survive eating poison. Scientists study the creative antitoxin defenses in these animals to discover treatments for poisoning.

Humans may be the ultimate invasive species

Originating in East Africa, Homo sapiens migrated across the world beginning about 60,000 years ago and directly harmed countless species by consuming resources and modifying ecosystems to serve our needs. While meeting the definition of an invasive species, some ecologists argue the opposite, claiming that humans have helped preserve numerous species.

From 1970 to 2017, invasive species have caused $1.28T in damage globally

The costliest species were the Asian tiger and yellow fever mosquitoes ($149B), which arrived in the US from Asia and sub-Saharan Africa, respectively. The bulk of their damage came from their transmission of diseases such as Zika, chikungunya, and dengue. (Some readers may experience a paywall.)

How scientists know invasive nutria were likely introduced to California by humans

Although native to South America, DNA testing of the semiaquatic rodents showed they are closely related to a population in Oregon, suggesting they were deliberately transported into the state. First identified in the San Joaquin Valley in 2017, the distance, terrain, and lack of nutria between the two regions has allowed researchers to rule out natural migration.

Invasive species may harm new ecosystems via the spread of disease

Besides damaging native species through direct interactions such as competition for resources and predation, invasive species may come from environments with greater biodiversity than the new environment. This makes them more likely to carry pathogens unfamiliar to native species, increasing the risk of biodiversity loss.

Feral and free-ranging cats rank among the most harmful invasive species

Transported across the planet by humans, cats can now be found in many environments and are estimated to kill about 2 billion birds each year in the US. Studies suggest cats have contributed to the extinction of at least 63 species worldwide.

An invasive, tree-killing beetle may threaten large swaths of Australia

A Curtin University study warns that large parts of Australia, including major cities and farming regions, could be highly vulnerable to the fast-spreading polyphagous shot hole borer, which releases a fungus that can starve trees of nutrients. The tiny insect has already caused severe damage across the Perth metropolitan area.

Invasive species can harm infrastructure and threaten human health

The wildfires in Hawaii in 2022 were made worse by flammable invasive grasses introduced from Africa as livestock pasture, and Zebra mussels native to the Caspian and Black Seas have spread across Europe and the US, where they can clog power plant pipes. Invasive mosquitoes can carry diseases, such as dengue and malaria.

Some invasive species can provide benefits to ecosystems over time

In the 1990s, round gobies were introduced into the Great Lakes, rapidly spreading and competing with local sculpin and logperch. However, Lake Erie watersnakes, which were on the endangered species list, shifted their diet to be almost entirely made up of the plentiful round gobies, contributing to their loss of endangered status in 2011.

How we helped make Aedes aegypti mosquitoes such a problem

Mosquito genome sequencing data suggests that Aedes aegypti mosquitoes first started specializing on human blood around 5,000 years ago—when climates shifted and humans started domesticating plants in Africa and stored large amounts of water that may have attracted the bugs.

The most effective method of managing invasive species is prevention education

Controlling a spread after a species has become established in an area is much more costly and time-consuming than early detection and rapid response. Control methods include the purposeful introduction of predators, the use of pesticides, herbicides, fungicides, and insecticides, and physical collection and removal.

Microbial research suggests shifts in diverse populations may help an invasive species establish itself

In 1958, English ecologist Charles Elton suggested that diverse ecosystems should be more resistant to invasive species because gaining a foothold would be more challenging when resources are more thinly spread. However, in lab-grown microbial ecosystems with greater biodiversity, population volatility opened more ecological roles that invasive species could easily fill.

Some invasive species' populations have been controlled by turning them into cash crops that can be harvested and sold to produce useful materials.

The giant African harvester ant is rising in popularity as a pet and fueling illegal global trade, with creatures sometimes costing as much as $220.

Distinct plant species evolved to produce caffeine as a pesticide

Although it provides a defense against insects trying to eat caffeine-bearing plants, the molecule is an example of exaptation, where its original function was repurposed over time. Studies show that some plants now produce caffeine-laced nectar to help pollinators move more quickly and pollinate more efficiently.

Fungi have been used to restore island habitats in the central Pacific

After removing 1.5 million invasive coconut palm trees and eradicating the black rats that fed on them, as well as seabirds and crabs, conservationists working with the US Fish and Wildlife Service identified areas where fungi could be transplanted to provide nutrients to native trees. These trees serve as nesting sites for seabirds whose guano nourishes coral reefs.

Invasivorism is a form of ethical eating focused on eating invasive species

The culinary approach helps combat the growth of invasive species populations by increasing demand for dishes made with them, but some suggest that creating a market for these species may help prolong their presence by moderating control. Some diners have expressed reluctance toward consuming more exotic species, such as nutria—raccoon-sized rodents.

Supertoxic rat poisons are wreaking havoc on unintended targets, including predator birds, mammals, amphibians, crustaceans, and insects.

Florida: the invasive pythons capital of the world

As invasive pythons choke the life out of South Florida, it’s down to a loose-knit group of thrill-seeking bounty hunters to get rid of them.

View some of the most invasive species in US waters

Introduced in the late 1600s from Eastern Asia, the goldfish is considered the first invasive fish in North America. The venomous lionfish is safe to consume, but catching it is complicated by its reluctance to respond to hook-and-line-style fishing attempts.

Some invasive plants, such as English ivy, maiden grass, and Norway maple, can swiftly take over gardens and damage yard structures if left unchecked.

Synthetic biology can prevent extinction by creating create disease-resilient plants and animals

Through gene editing and the deployment of artificial cells, scientists can leverage learnings from the genetic sequencing of animals with known resistances to protect endangered species. Gene editing of certain species, such as mosquitoes, can also reduce their ability to spread diseases like malaria between humans.

Researchers are breeding genetically modified mosquitoes to be malaria-resistant.

Some mosquitoes are key pollinators—and eat disease-carrying mosquitoes.

Canine inspectors can help detect potential carriers of invasive insects

At ports of entry in the US, Customs and Border Protection agents use dogs to sniff for forbidden foods and other items that are known to harbor invasive pests. Agents also physically inspect items such as flowers to prevent entry by species that may harm US agriculture.

Cross-species transplantation has been attempted in medicine for more than 300 years.

Climate change creates conditions for more invasive species

Increasing temperatures shift the conditions native organisms are accustomed to, allowing those from warmer climates to move in with a greater chance of survival. Drought stress can cause invasive plants to absorb less herbicide, limiting the effectiveness of the control method, while melting ice can open new Arctic shipping routes, expanding the transport of species.

More than half of the 7,000 'kissing bugs' locals sent to Texas A&M University had parasites

Texas A&M University scientists began a community science program in 2012 asking people to send in kissing bugs (any of the 11 species of bugs potentially infected with Trypanosoma cruzi parasites). About 1,500 people sent in over 7,000 bugs for scientific research, and about 55% of the bugs were infected with the parasite that causes Chagas disease.

Mosquitoes are the world's deadliest animal, but gene drives could kill them.

The American cockroach is actually from Africa—an apparent hitchhiker aboard ships carrying enslaved people—with evidence suggesting it may have arrived in the New World as early as the 1600s.

Wolbachia is also being used to slash mosquito numbers

The naturally occurring bacterium does not naturally infect Aedes aegypti mosquitoes, but communities in locations including California and Texas have released male mosquitoes infected with Wolbachia and reported a significant drop in subsequent mosquitoes: When infected males mate with uninfected wild females, the eggs don't hatch.

Malaria mosquitoes in a lab were wiped out using CRISPR

Scientists at Imperial College London disabled a gene in female Anopheles gambiae mosquitoes to make them infertile and propagated the infertility mutation at unnaturally high rates using a gene drive. The entire population collapsed within a dozen generations, showing promise for subsequent with mosquitoes in mimicked tropical environments.

How Guam became an island of snakes and spiders

The US territory of Guam has 40 times the number of spiders of nearby islands, and a voracious collection of snakes which has nearly emptied it of any native birds. Researchers took it upon themselves to count the species and determine what turned the island into such a haunt of arachnids and serpents, where walking into the woods can mean navigating endless layers of spider webs. Find out more here.

Salvador Dalí had pet anteaters he (supposedly) took on walks

Known for his adept and weird public relations stunts, Dalí kept exotic pets, such as an ocelot named Babou, as well as anteaters. The insectivorous mammal accompanied him on walks (though it may have just been for a photo op) and on talk show appearances.

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

Genetic analysis suggests Anopheles mosquitoes fed on humans some 1.8 million years ago.

West Nile Virus has been detected in American alligators, and outbreaks have led to substantial economic losses on alligator farms.

Native, wild bees are at much greater risk of extinction than honey bees

It is estimated that there are more honey bees, which often compete with native bees for resources, on the planet than at any point in human history. Meanwhile, 40% of invertebrate pollinator species, including wild bees and butterflies, face extinction in the coming decades.

In the 1930s, three Australian soldiers were sent to fight emus with machine guns—and lost

As part of a post-WWI initiative to turn veterans into farmers, soldiers were given plots of land. After emus were found damaging the farmland, three men were sent to handle the flightless birds. These men ended up losing to the second-largest bird species in the world and potentially exacerbating crop losses by sending swaths of the birds running and trampling over wheat.

Efficiency of commercial honeybees may exacerbate population declines in native bees

Commercial beekeepers are increasingly breeding honeybees on public lands, raising concerns among environmentalists that they’ll compete with and introduce new diseases to already threatened native pollinator populations. However, native species alone are often unable to meet the pollination levels required to meet necessary crop yields.

Anopheles mosquitoes are developing resistance to insecticides.

Two invasive termite species are threatening Florida homes

Asian subterranean and Formosan subterranean termites have been found in northern and coastal counties, respectively. About half of all structures in the urban South Florida metropolitan area could be at risk of infestation by one or both species by 2040.

Billions of flies are being dropped from the sky

The US is dropping billions of sterile flies to stop a deadly parasite. Screwworm maggots eat animals alive, so scientists are collapsing the population by ensuring females can’t reproduce.

Watch Cordyceps, a parasitic fungus, turn an ant into a ‘zombie’

This National Geographic TV clip shows how a parasitic Cordyceps species—sometimes colloquially called the “zombie ant fungus”—controls an ant’s behavior and kills its host. The fungus can rapidly wipe out entire insect colonies.

These invasive spiders are weaving their way across the US

The Joro spider was first spotted in the US in 2013 and has since spread throughout the Southeast. Get the 101 on this massive (and massively) invasive Asian spider in this article and infographics.

Although many insects are colloquially referred to as bugs, insects are only considered true bugs if they possess a proboscis—a straw-like mouthpart that can pierce surfaces and suck up fluids.