In North America, the most invasive species include the snakehead fish, the Burmese python, the giant African snail, fire ants and the Asian carp. Troublesome invasive plants include kudzu, purple loosestrife, oriental bittersweet, Japanese knotweed and cogongrass.
An invasive species is a non-native species in an ecosystem that grows or reproduces more quickly than the native plants competing for the same niche and can cause harm to economy, environment and human health. As of 2015, the United States suffers as much as $120 billion per year in losses due to invasive species, according to the Center for Invasive Species and Ecosystem Health. These losses occur as the results of limitations on land use and biodiversity; negative impact on hunting, fishing, camping, bird watching and other outdoor recreational activities; destruction of the food chain for native wildlife; and the harmful impact on agriculture.
Invasive species spread primarily through human activities. They hitch rides on ships and in shipments of wood products. Sometimes introduced as ornamental plants or pets, they cause problems after they enter into the wild. To prevent the spread of invasive species, the National Wildlife Federation recommends landscaping with native plants, cleaning equipment used for outdoor activities regularly, buying firewood locally when camping and reporting sightings of invasive species to county extension agents or local land managers.