To be considered invasive, a species must be:

• Non-native to the area (introduced by humans, usually)
• Able to spread or reproduce rapidly
• Harmful to the environment, humans, or society

Not all introduced species are considered invasive (think: dandelions), and neither are all harmful species (think: poison ivy). It is the combination of these qualities, along with the ability to multiply and spread rapidly, that earns invasive species this undesirable title.

There is no "one size fits all" for invasive species; they are present in all different types of ecosystems- both aquatic and terrestrial- and come in many forms, including: plants, insects, first, mammals, and birds. This website focuses on plant invasive species.

Source: New Brunswick Invasive Species Council