Invasive exotic species are plants and animals that are not from here but have been introduced and are thriving in the absence of their natural controls, to the detriment of our native species. Kudzu is perhaps the most famous of these, a Japanese plant widely planted in the last century, but there are a host of others, including the chestnut blight that removed chestnuts from our Appalachian forests, the balsam woolly adelgid which has killed Fraser firs on our highest mountaintops, and the hemlock woolly adelgid which is killing hemlock trees.