How do invasive species get to the USA?
Invasive species arrive in the United States through many different pathways and may be carried by vectors; some pathways are intentional, others accidental. For example Japanese stiltgrass (Microstegium vimineum) was probably accidentally introduced to the United States as dried packaging material in shipments of ceramics. The sudden 1999 appearance of West Nile virus in the metropolitan New York City area made scientists suspect an infected animal had arrived at a NYC airport, but the epidemiology is difficult to track. Mosquitoes (mostly Culex species) are the most common vectors (carriers of a pathogen) that spread West Nile virus.
