If you picnic in a Texas park, chances are you’ll encounter fire ants – a notorious pest that can deliver painful, itchy stings. This invasive species, like many others, is not only annoying but also expensive and destructive. From Texas to Taiwan, non-native animals, plants, bacteria, fungi and viruses damage economies and ecosystems.

  An invasive species is any kind of living thing that isn’t native to an ecosystem and causes harm. Sometimes non-native species are imported by accident, like in the 1930s when cargo ships from South America inadvertently took fire ants to North America. Other times non-native species are imported deliberately. Some types of Asian fish that were originally imported to the U.S. from China to clean fish farms escaped and entered rivers. Green iguanas were brought to Taiwan as pets, but irresponsible owners released them. The same thing happened in Florida with Burmese pythons.

  Non-native species have even been imported for sentimental reasons. A man once released dozens of European starlings in New York in an effort to bring all the birds mentioned in Shakespeare’s writings to America. Today, millions of starlings cause over $800 million in damages to U.S. agriculture every year.