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The Most Damaging Invasive Species in the World

Updated May 28, 2019 10.5k votes 790 voters 30.6k views102 items

List RulesVote 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: Todd Moon / flickr / CC-BY-NC 2.0

    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.

    Too invasive?
  • Photo: This Year's Love / flickr / CC-BY-NC-ND 2.0

    Black Rat

    Origin: SE Asia

    Originally from tropical Asia a long, long time ago, the black rat is most likely one of the first invasive species to ever be inadvertently distributed by humans. It is thought to have reached Europe by the first century A.D. before spreading across the globe on European ships. Since then, the black rat has thrived in just about every region of the world, and has adapted with ease to rural, urban, and suburban environments alike. Unfortunately, its success as a species alongside other rat species, has caused dramatic population declines and even extinction of countless bird, reptile, and other small vertebrate species all around the world.

    Too invasive?
  • Photo: coniferconifer / flickr / CC-BY 2.0

    Asian tiger mosquito

    Origin: Northern Asia

    This small, striped day-biter has been in the news in recent years in California, having newly arrived to join the phalanx of ultra-annoying mosquito species that already live there. Previous to California, it was first found in the US in 1985 in Texas. Since that time they have been spreading rapidly and unabated across the country. They prefer warm weather, so they have been identified in every county in Georgia, Florida, South Carolina and Tennessee, as well as many counties in surrounding states. They breed in small puddles of standing water near human habitation, in diverse places, varying from cemetery vases to junk piles. Like other invasive species, the Asian tiger has out-competed native mosquitoes, such as Aedes aegypti, the yellow fever mosquito, but that's not necessarily good. The tiger mosquito can spread diseases too, such as West Nile, dengue fever or Eastern equine encephalitis. In fact, its habit of staying close to where people live and biting multiple hosts in the daytime, make it an even more efficient vector for some diseases. Stay safe by following standard anti-mosquito protocols; including removing any standing water source from near your house if possible, no matter how small.

    Too invasive?
  • Photo: Sharon Suzuki-Martinez / flickr / CC-BY-NC 2.0

    Africanized Honey Bee

    Origin: African/European Hybrid

    The Africanized honey bee is a slightly unusual case, a bit of a Frankenstein's monster. It's a species cross-breed between aggressive Tanzanian bees and docile European honey bees. This was done as a way to try and increase honey production, however, the result was a very angry honey bee. That would have been the end of the story, but unfortunately in 1957, a beekeeper in charge of the hybrids accidentally released 26 Tanzanian queens in Sao Paolo, Brazil. These queens went out, found some european honeybees and multiplied. These hybrids are aggressive and hyper-territorial. They out-compete any native bees in the region they occupy. Africanized honeybee swarms have been known to invade regular honey bee hives, kill the European honey bee queen and install their own leader. They are less likely to store honey like the domesticated bees and they are quick to abandon a hive. The bees first infiltrated the U.S. in 1990 and have since spread to the southern parts of many states, including California, Nevada, Utah, Arizona, New Mexico, Texas, Oklahoma, Louisiana, Arkansas and Florida. Despite what fun TV movies of the week might make you think, their sting is no more toxic than any normal honey bee, however, because of their intense aggression, they have been known to swarm easily and sting many times, making them a threat to humans as well as honey production. 

    Too invasive?