Invasive species are organisms that quickly adapt to a new environment. They reproduce and spread rapidly, and they often displace organisms that originally lived there.

Many invasive species are exotic--like the Asian Longhorned Beetle to the right. That means that they are not native to the local environment. Other invasive species may be native, but may rapidly reproduce and become nuisances.

Plants, animals, and pathogens can become invasive. If any living thing is introduced into a new place where it has no natural enemies, it can quickly take over and become a real threat. It can quickly knock the whole environment out of balance.

Disturbances such as strip mining, logging or leveling land at construction sites often creates opportunities for invasive species to move in. Or, you may have a relatively undisturbed area, where a new species is introduced and the natural balance begins to shift.

For centuries, humans have intentionally taken new plant and animal species to different parts of the world. Some of these have been very beneficial--wheat from Egypt or cattle from Asia--others have not worked out so well.