Invasive Species

Cheatgrass and other invasive annual grasses continue to expand into the sagebrush ecosystem in the West and are fueling larger and more frequent wildfires. The life cycle of cheatgrass differs from most native grasses in that it dries out early in the season while native grasses are still green and producing seeds. This fuels fires earlier in the season and cheatgrass spreads quickly following...

Invasive species are costly, disrupt natural ecosystems, and consequently threaten native species. Phragmites, a tall wetland grass, has been a part of U.S. wetlands for many years. However, a strain from Europe, introduced in the early 19th century, aggressively displaces the native strain and has spread across the U.S. and Canada. These aggressive invasive plants form highly dense stands that...

European green crabs are one of the most widespread invasive marine species on the planet. Where they are abundant, green crabs outcompete other native shellfish. They are voracious eaters and a major predator of clams, mussels, and oysters. They also actively disturb bed sediments, leading to the loss of the eelgrass that serves as essential habitat for Dungeness crab and Pacific salmon. USGS is...

Feral pigs are invasive animals first introduced in the continental United States during the 1500s by European sailors. The animals are a problem across the Southeastern and the Western United States. Large numbers exist on Federal lands, including National Wildlife Refuges and National Parks, as a result of illegal releases and high reproductive rates. With adequate nutrition, breeding occurs...

The parasitic sea lamprey invaded the Great Lakes in the mid-20th Century devastating valuable native fisheries and coastal economies. The USGS’ Upper Midwest Environmental Sciences Center and the Great Lakes Science Center’s Hammond Bay Biological Station, in collaboration with the Great Lakes Fishery Commission, have been and continue to lead research on sea lamprey control, providing the...

Lionfishes ( Pterois volitans and P. miles ) have established self-sustaining populations and spread throughout the Western North Atlantic, Caribbean Sea, and Gulf of Mexico. Although there are reports of lionfish sightings from decades past, the species have considerably increased in numbers and spread since 2000. The remarkable speed with which lionfishes have invaded the region is unprecedented...

Argentine black and white tegus are large, highly reproductive, long living terrestrial lizards native to South America. Two established populations of tegu are in Florida, each likely coming from an escaped or released domesticated pet. Tegus eat a variety of plants and animals, but most concerning is their preference for reptile and bird eggs. USGS research on tegus includes developing and...

Scientists with the USGS Brown Treesnake project conduct research on this snake species, including control tool development and validation, ecology and ecological impacts, and early detection methods. The program has been expanded to include other invasive reptiles, such as the Burmese Python, Boa Constrictor, and Northern African Python in Florida and invasive watersnakes in California.

USGS scientists continue to conduct research on invasive Burmese pythons in Everglades National Park and other DOI lands in South Florida to aid in the management of these large, voracious constrictor snakes. Our research on Burmese pythons has focused on developing and testing methods for detection and control, predicting potential range of the species in the U.S., understanding thermal...

Invasive zebra and quagga mussels (collectively called dreissenid mussels) have significant ecological and economic effects. Dreissenids negatively affect industrial and municipal infrastructure, recreational water users, and they severely alter aquatic ecosystems by consuming algae and plankton. USGS has been conducting research on rapid response and control of dreissenid mussels in the Great...

Bighead, black, grass, and silver carp are sometimes referred to collectively as invasive carp. The term invasive carp replaced Asian carp in 2021. which are native to China, were originally stocked in aquaculture facilities to control algae, snails, and vegetation. These species have invaded the Mississippi River and are now established throughout the lower and middle Mississippi River Basins and...

Acalolepta aesthetica , known as the Queensland Longhorn Beetle, is a wood-boring beetle that has recently emerged as a problematic invader on the Hawai‘i Island. We are determining its current range and identifying patterns of host tree use, focusing on culturally important and native trees.