Looking for a good way to describe the impact of unchecked labor unions? A blurb in the latest National Review offers an apt metaphor:

Lacking the evolutionary finesse that keeps most parasites from killing their host organisms, the American labor movement has driven the private firms that once employed its members offshore or into bankruptcy. Consequently, the only growth market remaining for the union movement is government. Republicans should be looking to limit this harmful influence on American public life, not to fortify it.