Maine is home to a long list of unwanted plants and animals that damage ecosystems and the economy, and pose a risk to public health. Many of these invasive species might live right in your backyard. But would you know if you saw one? This week, during National Invasive Species Awareness Week, it’s a good time to learn. But first, what is an invasive species? An invasive species is an organism — plant, animal, fungus, etc.