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An invasive species is an introduced, nonnative organism (disease, parasite, plant, or animal) that begins to spread or expand its range from the site of its original introduction and that has the potential to cause harm to the environment, the economy, or to human health.
A few well-known examples include the unintentional introduction of the West Nile virus, chestnut blight, the South American fire ant, zebra mussels, Burmese pythons, and sea lamprey. These are in addition to the intentional introductions of salt cedar (Tamarisk), kudzu vine, house sparrows, starlings, and nutria.
Harmful, non-native species can be found in all ecosystems across the United States. These species can cause costly economic and ecological damage each year including crop decimation, clogging of water facilities and waterways, wildlife and human disease transmission, threats to fisheries, increased fire vulnerability, and adverse effects for ranchers and farmers.
Learn more: USGS Invasive Species Program
Free-ranging snakes representing dozens of species from around the world are discovered in the United States in any given year, usually as a result of escapees or releases from the pet trade, but most of these don't appear to have established a reproductive population. Any animal can be problematic when released in places where it is not native. For example, the Brown Treesnake was introduced to...
Free-ranging, non-native reptiles representing dozens of species from around the world escape or are illegally released in the United States every year. Many of these species fail to establish reproductive populations, but some are successful. Florida is a major transportation hub and has a climate that is suitable for many invasive species across taxonomic groups. Due to the suitable climate, and...
Non-native Burmese pythons have established a breeding population in South Florida and are one of the most concerning invasive species in the area. Pythons compete with native wildlife for food, which includes mammals, birds, and other reptiles. Severe declines in mammal populations throughout Everglades National Park have been linked to Burmese pythons, with the most severe declines in native...
During all of their life stages, snakehead fish compete with native species for food and habitat. A major concern is that snakeheads might out-compete (and eventually displace) important native or other established predatory fish that share the same habitat. As adults, snakeheads can be voracious predators. Should snakeheads become established in North American ecosystems, their predatory behavior...
An unburned low elevation community in the central Mojave where the interspaces between shrubs have been filled in with a continuous layer of Mediterranean split grass Schismus barbatus. If a fire started here it would spread much more rapidly and be far more extensive than in a low elevation community where the interspaces are rocky or bare.
An unburned low elevation community in the central Mojave where the interspaces between shrubs have been filled in with a continuous layer of Mediterranean split grass Schismus barbatus. If a fire started here it would spread much more rapidly and be far more extensive than in a low elevation community where the interspaces are rocky or bare.
Snakehead fish are originally from China and Korea, but recently they've been found in Maryland, Virginia, Arkansas, California, and Florida.
Snakehead fish are originally from China and Korea, but recently they've been found in Maryland, Virginia, Arkansas, California, and Florida.
Adam Sepulveda, research zoologist at the USGS Northern Rocky Mountain Science Center, explains a scientists at NOROCK are using environmental DNA — the identification of species through biological information they leave behind in their habitat — to detect invasive species and how this method could change the way scientists find evidence of biodiversity in
Adam Sepulveda, research zoologist at the USGS Northern Rocky Mountain Science Center, explains a scientists at NOROCK are using environmental DNA — the identification of species through biological information they leave behind in their habitat — to detect invasive species and how this method could change the way scientists find evidence of biodiversity in
An invasive American bullfrog with tracking device.
An invasive American bullfrog with tracking device.
Invasive New Zealand mud snails as seen under a microscope.
Invasive New Zealand mud snails as seen under a microscope.
Invasive sea lamprey prey on commercially important fish species such as lake trout, living off of the blood and body fluids of adult fish. It is one of many fish species that USGS scientists study from the USGS Research Vessel Muskie. These lamprey belong to the Great Lakes Fisheries Commission.
Invasive sea lamprey prey on commercially important fish species such as lake trout, living off of the blood and body fluids of adult fish. It is one of many fish species that USGS scientists study from the USGS Research Vessel Muskie. These lamprey belong to the Great Lakes Fisheries Commission.
This image is of invasive tamarisk (salt cedar) growing on the banks of the Colorado River.
This image is of invasive tamarisk (salt cedar) growing on the banks of the Colorado River.
A boar of about 260 pounds near Pecan Island, Louisiana, with LOTEK tracking collar attached and ready for release.
A boar of about 260 pounds near Pecan Island, Louisiana, with LOTEK tracking collar attached and ready for release.
An adult male mouflon stands broadside to the camera in a grassy field on Hawai‘i Island. Mouflon were introduced to Hawai‘i for trophy hunting in the 1950s.
An adult male mouflon stands broadside to the camera in a grassy field on Hawai‘i Island. Mouflon were introduced to Hawai‘i for trophy hunting in the 1950s.
Adult lionfish, approximately 250 mm total length.
Adult lionfish, approximately 250 mm total length.
The zebra mussel (Dreissena polymorpha) is a small, non-native mussel originally found in Russia. In 1988, this animal was transported to North America in the ballast water of a transatlantic freighter and colonized parts of Lake St. Clair. In less than ten years, zebra mussels spread to all five Great Lakes.
The zebra mussel (Dreissena polymorpha) is a small, non-native mussel originally found in Russia. In 1988, this animal was transported to North America in the ballast water of a transatlantic freighter and colonized parts of Lake St. Clair. In less than ten years, zebra mussels spread to all five Great Lakes.
The invasive red lionfish (Pterois volitans) waits to be hauled to the surface, where it will eventually be used by NOAA to conduct lab studies on lionfish reproductive biology, age, and growth.
The invasive red lionfish (Pterois volitans) waits to be hauled to the surface, where it will eventually be used by NOAA to conduct lab studies on lionfish reproductive biology, age, and growth.
Free-ranging snakes representing dozens of species from around the world are discovered in the United States in any given year, usually as a result of escapees or releases from the pet trade, but most of these don't appear to have established a reproductive population. Any animal can be problematic when released in places where it is not native. For example, the Brown Treesnake was introduced to...
Free-ranging, non-native reptiles representing dozens of species from around the world escape or are illegally released in the United States every year. Many of these species fail to establish reproductive populations, but some are successful. Florida is a major transportation hub and has a climate that is suitable for many invasive species across taxonomic groups. Due to the suitable climate, and...
Non-native Burmese pythons have established a breeding population in South Florida and are one of the most concerning invasive species in the area. Pythons compete with native wildlife for food, which includes mammals, birds, and other reptiles. Severe declines in mammal populations throughout Everglades National Park have been linked to Burmese pythons, with the most severe declines in native...
During all of their life stages, snakehead fish compete with native species for food and habitat. A major concern is that snakeheads might out-compete (and eventually displace) important native or other established predatory fish that share the same habitat. As adults, snakeheads can be voracious predators. Should snakeheads become established in North American ecosystems, their predatory behavior...
An unburned low elevation community in the central Mojave where the interspaces between shrubs have been filled in with a continuous layer of Mediterranean split grass Schismus barbatus. If a fire started here it would spread much more rapidly and be far more extensive than in a low elevation community where the interspaces are rocky or bare.
An unburned low elevation community in the central Mojave where the interspaces between shrubs have been filled in with a continuous layer of Mediterranean split grass Schismus barbatus. If a fire started here it would spread much more rapidly and be far more extensive than in a low elevation community where the interspaces are rocky or bare.
Snakehead fish are originally from China and Korea, but recently they've been found in Maryland, Virginia, Arkansas, California, and Florida.
Snakehead fish are originally from China and Korea, but recently they've been found in Maryland, Virginia, Arkansas, California, and Florida.
Adam Sepulveda, research zoologist at the USGS Northern Rocky Mountain Science Center, explains a scientists at NOROCK are using environmental DNA — the identification of species through biological information they leave behind in their habitat — to detect invasive species and how this method could change the way scientists find evidence of biodiversity in
Adam Sepulveda, research zoologist at the USGS Northern Rocky Mountain Science Center, explains a scientists at NOROCK are using environmental DNA — the identification of species through biological information they leave behind in their habitat — to detect invasive species and how this method could change the way scientists find evidence of biodiversity in
An invasive American bullfrog with tracking device.
An invasive American bullfrog with tracking device.
Invasive New Zealand mud snails as seen under a microscope.
Invasive New Zealand mud snails as seen under a microscope.
Invasive sea lamprey prey on commercially important fish species such as lake trout, living off of the blood and body fluids of adult fish. It is one of many fish species that USGS scientists study from the USGS Research Vessel Muskie. These lamprey belong to the Great Lakes Fisheries Commission.
Invasive sea lamprey prey on commercially important fish species such as lake trout, living off of the blood and body fluids of adult fish. It is one of many fish species that USGS scientists study from the USGS Research Vessel Muskie. These lamprey belong to the Great Lakes Fisheries Commission.
This image is of invasive tamarisk (salt cedar) growing on the banks of the Colorado River.
This image is of invasive tamarisk (salt cedar) growing on the banks of the Colorado River.
A boar of about 260 pounds near Pecan Island, Louisiana, with LOTEK tracking collar attached and ready for release.
A boar of about 260 pounds near Pecan Island, Louisiana, with LOTEK tracking collar attached and ready for release.
An adult male mouflon stands broadside to the camera in a grassy field on Hawai‘i Island. Mouflon were introduced to Hawai‘i for trophy hunting in the 1950s.
An adult male mouflon stands broadside to the camera in a grassy field on Hawai‘i Island. Mouflon were introduced to Hawai‘i for trophy hunting in the 1950s.
Adult lionfish, approximately 250 mm total length.
Adult lionfish, approximately 250 mm total length.
The zebra mussel (Dreissena polymorpha) is a small, non-native mussel originally found in Russia. In 1988, this animal was transported to North America in the ballast water of a transatlantic freighter and colonized parts of Lake St. Clair. In less than ten years, zebra mussels spread to all five Great Lakes.
The zebra mussel (Dreissena polymorpha) is a small, non-native mussel originally found in Russia. In 1988, this animal was transported to North America in the ballast water of a transatlantic freighter and colonized parts of Lake St. Clair. In less than ten years, zebra mussels spread to all five Great Lakes.
The invasive red lionfish (Pterois volitans) waits to be hauled to the surface, where it will eventually be used by NOAA to conduct lab studies on lionfish reproductive biology, age, and growth.
The invasive red lionfish (Pterois volitans) waits to be hauled to the surface, where it will eventually be used by NOAA to conduct lab studies on lionfish reproductive biology, age, and growth.