According to the January 15th Wall Street Journal, 30 new invasive insects are discovered annually. The increased rate is a byproduct of our increasing global trade and transportation. The economic impact in the US is estimated at $133.6 billion including "control and prevention such as pesticides, inspection programs at ports and damage to crops."
There have been an estimated 50,000 species of plants, animals and insects introduced through our history as a country. Many well known examples such as starlings, thistle, and zebra mussels have become a part of everyday life.
Although the current article highlights hemlock woolly adelgids which are destroying the hemlocks in the great Smokey Mountains, it applies just as well to the challenge we have in protecting trees and inspecting imports from organisms such as the Emerald Ash Borer. We are all interconnected on the same planet in spite of our perceived regional and national differences.
