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.

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.

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.

View the steps you can take to stop invasive species

Individuals who are outside should make sure to wash any outdoor gear and equipment with appropriate tools to limit the spread of seeds and other microorganism-carrying debris across locations. Pets, horses, and other animals should be similarly brushed, and firewood should be burned where it is purchased.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it.

Poison ivy is projected to be larger and more resilient due to climate change.

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.

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.

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.

Scientists testing how climate change affected plants found in a yearslong simulation study that poison ivy grew 70% faster than it did without extra carbon dioxide.

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.

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.

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 are the third biggest threat to Earth's biodiversity

According to the World Wildlife Fund's Living Planet Report 2020, changes in land and sea use account for about half of all recorded threats to the diversity of the planet's species. Species overexploitation is the second-largest proportional threat at 24%, while invasive species make up 13%.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity.

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

Adding garden beds with blooming plants to an existing lawn can support bees

Blooming wildflowers, shrubs, and trees can provide the nectar and pollen these pollinators need but do not get from grass. Other tips include leaving patches of bare soil for ground-nesting bees to lay their eggs and filling birdbaths with large pebbles for them to land and drink from safely.

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.

Plants use physical and chemical defenses to protect themselves

Tree bark is difficult to chew and resistant to pathogens, while the waxy cuticle on the surface of leaves deters insects and microbes. Some plants possess thorns, spines, and prickles to discourage predators. Plant cells can also produce antimicrobial toxins or release compounds to alert parasitic wasps to lay eggs in attacking insects.

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.

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.

The ‘humongous fungus’ may be the largest organism on Earth at more than 2,300 acres

Discovered in 1988, when it was only covering 400 acres, this massive colony of Armillaria ostoyae, based in Oregon, has taken hold among the tree roots of the Malheur National Forest. It consists of a vast network of unique long black filaments of fungal tissue called rhizomorphs that grow under the soil and infect tree roots, nourishing the fungus but killing the trees. Researchers believe this fungal growth dates back more than 8,000 years and currently weighs approximately 35,000 tons.

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.

Poison ivy's characteristic rash is caused by an allergic response to an oily substance in the plant called urushiol.

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted and led to authorities' suspicions he was conspiring with the Russians.

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

In 1935, Australian scientists imported several hundred cane toads to hunt and eat beetles that were damaging sugar cane fields. However, the toads could not reach the bugs at the top of the plant or the grubs in the soil. Instead, they negatively affected native species populations as their numbers grew to over 2 billion.

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.

Citizen scientist volunteers can help identify invasive species in wilderness areas

Launched in 2005 by the Center for Invasive Species and Ecosystem Health at the University of Georgia, EDDMapS allows users can document invasive species sightings in the US and Canada in a web-based mapping system. As of February 2026, EDDMapS has over 8.6 million records, all freely available for querying.

Fertilizers provide essential nutrients to plants for their growth, including nitrogen, phosphorus, and potassium, but an overabundance of these nutrients may also harm plants.

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.

Search plants, butterflies, and moths native to your area

This tool from the National Wildlife Federation allows you to search by zip code for native plants, ranked by the number of butterfly and moth species that use them as host plants for their caterpillars, to help identify what you can grow to support local pollinators.

Chaos gardening involves scattering seeds without any planning

The trend is intended to produce colorful, dense gardens by mixing various seeds. While encouraging experimentation and lower stakes, the success of these gardens depends on choosing plants with similar needs and incorporating native, nectar-rich flowers.

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.)

Plastic debris across the ocean aids the spread of invasive species

The durable, long-lasting material can serve as a platform for living organisms to latch onto and ride over vast distances. After the 2011 earthquake and tsunami in Japan, a large dock carrying 100 tons of living organisms native to Japan washed up on Oregon's coastline, confirming the ecological threat.

Biosphere 2 revealed limitations in maintaining wildlife in unfamiliar environments

Trees appeared to become weak and more prone to breaking because a lack of wind caused them to no longer need to develop stress wood. The extinction of pollinators—potentially due to an explosion in the population of longhorn crazy ants—was also unexpected.

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.

Explore guides on pollinator-friendly plants native to where you live

Pollinators have co-evolved alongside specific plants from their natural habitat and see their populations increase in environments with these native flora. This collection offers recommendations for regional plants that can provide nectar and pollen, serve as host plants for caterpillars, and offer nest sites for specialist bees.

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.

See examples of hyperaccumulators, the plants that can harvest heavy metals

These ideal species for phytoremediation possess biochemistry that allows them to absorb and store these elements without being poisoned by their accumulation. Pycnandra acuminata, one such plant, has blue-green sap due to an abundance of nickel, which it captures from the nickel-rich soil in which it grows.