The Most Damaging Invasive Species in the World

Over 1.0K Ranker voters have come together to rank this list of The Most Damaging Invasive Species in the World
Voting Rules
Vote up the things that you believe are the most damaging invasives through direct or indirect experience.

Ecosystems on our planet are, as we have learned over and over as a species that seems to live outside them, much more fragile than we've given them credit for. Sometimes it only takes the introduction of one species to upend the whole boat. This can happen naturally... say a flood or a windstorm blows an invader into a new biome that is not prepared for it... but it is usually humans that are responsible for bringing these invaders in. Sometimes it is by accident, and other times we do it to solve a problem that we, ourselves, have created; then going on to make it so much worse. Insects and viruses can be carried across oceans by boats, on livestock or even our clothing. Animals can be imported as pets and then let loose... or imported as a possible resource, and then found to be deeply destructive and impossible to control. Island ecosystems are deeply vulnerable, often having completely endemic, carefully balanced food chains and interspecies relationships. The introduction of a single new animal can, and has, completely upended that balance. Large-scale agriculture is also vulnerable to a single invader that it has no defense against. We can struggle to right these human-caused wrongs, but often find ourselves helpless in the face of an imbalance we have no way to fight. This is a list of the most destructive invasive plants, animals and diseases on Earth. Vote up the ones that you have experienced the impacts of, either directly or indirectly.

Photo: Galen Parks Smith

  • Dutch Elm Disease
    Photo: Mary Gillham Archive Project / flickr / CC-BY 2.0
    327 VOTES

    Dutch Elm Disease

    Origin: Western Himalaya

    Accidentally brought to the US in 1930 via imported, infected logs from the Himalayas it wasted no time spreading among trees that had no natural resistance to the non-native invader. The first case of the fungus destroying American elms was immediate. Two years later it had spread across the east coast, wiping out trees in New Jersey. By 1970 it had destroyed 77 million trees. It spreads by bark beetles that feed on the trees -- it then impacts the ability of the tree to spread water and nutrients throughout itself and one by one the branches die, finally killing the tree. No American elm has yet to develop resistance to this devastating fungus. Dutch elm disease is widely recognized as the largest threat to elm trees in the United States.

    327 votes
  • Kudzu
    Photo: reallyboring / flickr / CC-BY-NC-ND 2.0
    532 VOTES


    Origin: Japan

    Going by several not-so-flattering nicknames, Kudzu is well known to areas that is is not native to. It's hard to miss, as it covers everything. The Kudzu vine is native to Japan, but arrived in the US in 1876 when it was featured at an expo as a hardy, fast growing vine that could fight soil erosion. Well. They weren't wrong about that part. Also known as the 'mile a minute' vine and the 'the vine that ate the south', Kudzu has been spreading across the country at 150,000 acres a year. In the right conditions, a length of vine can grow a foot in a single DAY. The vines themselves grow up to 100ft long and the plant can smother trees, houses, power lines and whatever else that can't move out of the way. It is drought and frost tolerant and practically unstoppable. Nothing can compete with it, and thus, it wins. This invasive easily sits in the top 10 of the worst case scenarios that happen when an organism has no natural barriers built into its ecosystem.

    532 votes
  • Red imported fire ant
    Photo: Metaweb (FB) / Public domain
    442 VOTES

    Red imported fire ant

    Origin: Brazil and Argentina

    Originating in Argentina and Brazil, there are few that have never heard of the fire ant, one of the worst invasives in the world. In the US, it is thought that the first ant arrived in Mobile, Alabama via cargo ship somewhere between 1933 and 1945. In Australia it is believed to be closer to 2011. It has since caused billions of dollars in damage to the areas it now infests. The ants thrive in urban areas, so their presence may deter outdoor activities, but more damagingly, nests can be built under structures such as pavements and foundations, which may cause structural problems, or cause them to collapse. They also can damage equipment and infrastructure and impact business, land, and property values. As the workers are attracted to electricity, they can swarm electrical equipment and destroy it. In agriculture, they can damage crops, damage machinery, and threaten pastures. They are known to invade a wide variety of crops, and mounds built on farmland may prevent harvesting. They also pose a threat to animals and livestock, capable of inflicting serious injury or killing them, especially weak or sick animals. So far, the only ways of controlling these ants has been found to be baiting and pesticides. Due to its capability for damage, the ant has become one of the most studied insects on earth.

    442 votes
  • Brown Marmorated Stink Bug
    Photo: Anita363 / flickr / CC-BY-NC 2.0
    342 VOTES

    Brown Marmorated Stink Bug

    Origin: China

    This damaging and hard-to-eradicate insect is believed to have first arrived in the US in packing crates or on machinery shipped from China. The first documented specimen was collected in Allentown, Pennsylvania, in September, 1998.  Not only does it smell bad - hence the name - but it has the ability to eat its way through a variety of crops, from cotton to apple. It has an uncanny and unfortunate ability to avoid pesticides. Once introduced to an area, this pest can take years to build up enough population to destroy an entire crop... somewhere between 8 and 10 years depending on the local climate and situation. Once established, however, the numbers can explode and new populations can spread, partly because the climate of the US is paradise for the stink bug. In fact, there does not appear to be any environmental limiting factors that are slowing their spread across the United States. They also are extremely mobile insects capable of moving from host to host without causing disruption in their reproductive processes. Currently it is estimated that BMSB populations will continue to grow and spread to other states, especially during unusual periods of warm weather.

    342 votes
  • Formosan Termite
    Photo: USDAgov / flickr / CC-BY 2.0
    262 VOTES

    Formosan Termite

    Origin: Taiwan

    Originating from Taiwan or perhaps China before that, the first Formosan Termite probably arrived in the US via ship. It was first reported in a Houston shipyard in 1965 and has since spread across the southern US. Sometimes called the super termite, this little bastard is one of the most destructive insects in the US. This particular species can tear through wood like a buzzsaw - faster than any other species.It is known to consume over 50 living plant species as well as structural lumber, plastics, asphalt and even thin metals. Not only is it an aggressive eater, but it is also territorial. They are very expensive pests to deal with. In Hawaii for example, annual costs to control them exceed $100 million dollars and in Florida, $60 million. Physical barriers such as special sand or wire mesh installed under buildings at the time of construction are used where Formosan subterranean termites are troublesome, but such barriers are very expensive. Expensive or not, a sobering statistic: once established, Formosan subterranean termite has never been eradicated from an area.

    262 votes
  • Zebra Mussel
    Photo: Todd Moon / flickr / CC-BY-NC 2.0
    367 VOTES

    Zebra Mussel

    Origin: E. Europe and W. Russia

    Another ballast water hitch-hiker, the fingernail sized Zebra mussel arrived from Europe in 1988 and established a colony in the great lake region. They soon spread their way through the lakes, down the Mississippi and throughout the eastern US. Ravenous filter feeders, they rapidly deplete the water of food, out-competing the native organisms. They cluster by the millions, clinging to every solid surface. They create a costly problem for power plants, cities and residents when they clog water intakes. They kill native mussels and they slice open the unsuspecting feet of any swimmer or pet that steps on them. There has yet to be found an efficient way to control them, but researchers have tried special paint that keeps them from adhering to docks and pipes. There has been some experimentation with ion emitters that the mussels seem not to like, but for the most part nothing has worked yet.

    367 votes