INVASIVE SPECIES

U.S. Fish and Wildlife officer Carlos Pages checks a Tagoo lizard at Miami International Airport on October 13, 2010. As officials mount a public, and so far unsuccessful, campaign to rid the Everglades of non-native Burmese pythons, more and more species are allowed into the U.S. that could bring disease or threaten native species. (Mike Stocker/Sun Sentinel/Tribune News Service via Getty Images)