Welcome to the downside of global trade. Along with cheap goods from China, linens from Europe and seafood from South America, a host of unwanted plants, animals, insects and microbes have been penetrating US borders.
iNVASIVE SPECIES
Invasive species are nothing new. The gypsy moth arrived in 1869, imported by a French scientist who hoped to crossbreed the insect with silkworms. Instead, America got a pest that denudes millions of trees a year.

Today, 7000 invasive species are already in the USA, outcompeting or eating their native cousins, killing crops and forests, upsetting nature's delicate balance. They're blamed for four in 10 endangered-species listings, and their economic toll is staggering: $137 billion a year, estimates one study. Little wonder that the General Accounting Office has labeled invasive species "one of the most serious yet least-appreciated environmental threats of the 21st century."

Read the entire article with TIPS on WHAT YOU CAN DO:
Can They Be Stopped?

Resources:
Invasive Species - gateway to Federal and State invasive species activities and programs

Nature Conservancy - Invasive Species Initiative