Because invasiveness is heavily subjective and context-dependent, there is no single "number one" invasive species globally. Instead, scientists and conservation bodies evaluate them by their environmental devastation, economic damage, or geographic spread.
Ten of the World's Most Invasive Species
Top 10 invasive species
The definition of the "biggest" invasive species depends on what you are measuring:
These are 10 of the most unwanted and threatening invasive species throughout the world.
A dragonfly has around 28,000 to 30,000 independent lenses (called ommatidia) in its two massive compound eyes. This grants them near 360-degree vision.
Due to poaching, habitat loss, and climate change, several species are at critical risk of completely disappearing from the wild by 2050. Leading conservation experts emphasize that the following animals face severe danger of extinction without immediate intervention:
Invasive species are non-native organisms that spread rapidly and cause significant harm to the environment, economy, or human health, largely because they lack natural predators in their new habitats.
Yes, planting kudzu is largely illegal. Because this aggressive vine grows up to a foot a day and destroys native ecosystems, it is classified as a noxious or invasive weed in numerous states and countries.
Animal overpopulation typically occurs due to invasive species introduction or the loss of natural apex predators. In the United States, common overpopulation threats include white-tailed deer, feral hogs, invasive Asian carp, and domestic pets.
Very few animals eat the invasive Tree of Heaven because its leaves and bark contain strong toxins and foul-tasting chemicals. However, a few specialized species consume it:
The “tens rule” hypothesizes that about 10% of all species transported to a new environment will be released or escape and become introduced species. Subsequently, 10% of those introduced species establish viable populations in the wild. Finally, about 10% of the established species become highly damaging.
Yes, from an ecological and conservation standpoint, domestic and feral cats are widely classified as invasive species. Because humans have introduced them to every continent except Antarctica, they have caused widespread ecological damage.
Plants are banned in the U.S. either because they are classified as Federal Noxious Weeds that threaten agriculture and local ecosystems, or because they are controlled substances.
Fish and wildlife are experiencing increased threats from climate change, land use, drought, extreme storm events, and invasive species and disease.
Water lettuce is banned in many areas because it is an aggressively invasive aquatic plant. It reproduces rapidly, forming dense mats that block sunlight, deplete oxygen in the water, and crowd out native species.
Permanently killing kudzu requires destroying its deep taproot and persistent root crowns. The most effective method is a multi-year combination of cutting the vines to the ground and applying systemic herbicides (like glyphosate, triclopyr, or clopyralid) to the fresh stumps.
So, can you sue your neighbor for bamboo damage? Yes—with the proper legal grounds, documentation, and guidance, you absolutely can. The law is on your side when invasive bamboo threatens your property, safety, and well-being. If you're dealing with bamboo damage from a neighbor's yard, contact Paula A.
The "worst" invasive species are those that cause irreversible ecological destruction, drive native wildlife to extinction, and cost billions in economic or agricultural damage. The globally recognized elite tier of invaders includes:
Biologically, humans are not technically considered an invasive species. By definition, an invasive species must be non-native to an ecosystem and cause environmental or economic harm. Because humans originated on Earth and naturally dispersed globally, our native range spans the entire planet.
An invasive plant is a non-native species whose introduction causes or is likely to cause harm to the environment, economy, or human health. Unlike typical non-native plants, invasive plants spread aggressively and lack natural predators, allowing them to outcompete and displace native species.
Yes, that figure is widely accepted by biologists and paleontologists. Scientists estimate that somewhere between 99% and 99.9% of all species that have ever lived on Earth are now extinct.
While many scientists warn that human activity is driving a sixth mass extinction, some researchers argue we aren't there yet. Paleontologists and biologists debate whether the current rate of biodiversity loss meets the extreme geological thresholds required to officially classify it alongside the five previous mass extinctions.
The title of the #1 rarest animal in the world is widely held by the vaquita (Phocoena sinus). It is the world's smallest porpoise and most endangered marine mammal.