invasive species
noun
- organism occurring in a new habitat
Wiktionary
noun
- Any species that has been introduced to an environment where it is not native, and that has since become a nuisance through rapid spread and increase in numbers, often to the detriment of native species.
“Grey squirrels are an invasive species in the UK, introduced from North America in the 1870s. They pose a problem for wildlife including endangered red squirrels, which they outcompete.”