1. Invasive species have large impacts on the ecosystems they invade.
Invasive Species Invasive species are plants, animals, or pathogens that are non-native (or alien) to the ecosystem under consideration and whose introduction causes harm by decreasing biodiversity 
Invasive species have large impacts on the ecosystems they invade.
affect the chemical makeup of the water,
availability of resources
even alter the food web
impact other species more directly through competition for resources. Because invasive species evolved with other competitors and native species evolved in the absence of invasive species they lack the ability to compete with invasive species. This gives invasive species the upper hand when resources become scarce
Leads to an overall decrease in biodiversity as the area invaded becomes less populated by native species and more taken over by invasive species
Invasive species are also expensive. They are costly to society in many ways through both, direct management, and decreased production. The annual estimated cost in the United States of invasive species control is about 120 billion dollars per year. It is estimated that the global cost of invasive species management is equal to five percent of the global economy.

2. Asian Long Horned Beetle

3. Japanese Knotweed

4. Chinese Mitten crab

5. Carp

6. Brown trout

7. Feral Hog

8. European Starling

9. Zebra Mussel

10. European Green Crab

11. Nutria

12. Fire Ant

13. English Sparrow

14. Purple Loosestrife

15. Mimosa

16. Leafy Spurge

17. Kudzu

18. Chinese Tallow

19. Salt Cedar

20. English Ivy

21. Himalayan Blackberry