Invasive species are among us, and they're likely here to stay. These invaders from foreign lands alight on new soil and decide they'd like to set up housekeeping, often wreaking havoc on the local ecosystem, and costing millions in property and habitat destruction to beleaguered human bystanders.
"When people move either by accident or on purpose certain plants, animals, or microorganisms to places where they are not part of nature they invade and cause great harm," Chris Dionigi, Deputy Director of the National Invasive Species Council, told GlobalPost.
Here's some of the most loathsome offenders.
1. Burmese python
The massive Burmese python is perhaps the most menacing invasive species in America, as one might expect from a gigantic, aggressive Southeast Asian snake. It's not entirely clear how these beasts first made it to Florida — zoo escapees from hurricanes and lousy pet owners are likely culprits — but the reptiles soon realized that the balmy, marshy conditions in the Everglades were close to their homeland.
Capable of consuming smallish alligators, wild boar, and other seemingly unlikely prey, these tenacious creatures can get massive. Earlier this month, a 17-foot long, 165-pound female was caught in the Florida Everglades - and she was carrying 84 eggs.
Read more from GlobalPost: Record-breaking Burmese python captured in Florida Everglades (VIDEO)
Even though Burmese pythons are currently restricted to Florida, climate change could mean these giant snakes could show up in more northern climates in the near future, according to USA Today.
Although wild pythons have yet to kill anybody insofar as I can determine, pet Burmese pythons have been known to occasionally strangle small children and pets. (Parents: for God's sake, get a Beagle.)
Curiously enough, it's still extremely easy for Americans to purchase pet Burmese Pythons on the Internet, for a mere $299.99. They're not offered on Amazon.com yet, but stay tuned!
There is a hunting season in Florida on Burmese pythons, in case you want to mount a real conversation starter above your living room couch.
2. Zebra mussels
These aren't the benevolent kind of mussels you cook in white wine with some garlic and fennel. These menacing bivalves have clogged up waterways, destroyed boats, and generally made life miserable on the water for wide swaths of the USA.
The mussels are native to the inland Eastern European Caspian sea, according to this handy King County, Washington website, and only arrived here around 1988, likely clinging to the hullls of European ships undetected. The little jerks soon gummed up the Great Lakes with dizzying speed, and it's currently estimated that there's around 700,000 mussels per square meter in the hardest hit bits of the Great Lakes.
The mussels ruin ecosystems because they filter out nearly all the nutrient-rich plankton in the waters they infest, starving other creatures that rely on these nutrients, according to the Gulf of Maine Research Institute.
Read more: America's Least Wanted - PBS
Zebra mussels damage property: the GMR says the mussels can clog "water-intake pipes and screens of drinking water facilities, industrial facilities, power generating plants, golf course irrigation pipes, cooling systems of boat engines, and boat hulls."
That also includes your fancy multi-million dollar yacht. Zebra mussel don't care.
And no, we can't eat them. Zebra mussels don't get very big, for one thing — and as filter feeders, they soak up all the unpleasant gunk in the water. Further, according to Buffalo Rising Online, zebra mussels store botulism toxins in the bodies, causing great harm to the animals that do eat them. Yummy!
Bunny rabbits may be fluffy and adorable, but they're an absolute scourge in Australia, where the hopping creatures have done a remarkably thorough job of eradicating native wildlife. European rabbits obviously aren't much of a menace individually, but their remarkable powers of reproducing — and eating — mean that they can decimate farms and destroy ecosystems with shocking speed.
A mere 24 rabbits introduced into Australia in 1859 as a hunting diversion for European settlers quickly ballooned into 10 billion hopping menaces by the 1920s, according to the Foundation for Rabbit Free Australia. The animals devastated farmers crops and destroyed the land's carrying capacity, according to this University of Texas report. A massive "rabbit proof fence" erected in Western Australia to stop the bunny plague didn't help much.
Rabbits are believed to be responsible for the extinction of a number of small marsupials in the same ecological niche in Australia, and although human-introduced disease have made a dent in their numbers, they continue to threaten native plants and animals.
Here's Animal Planet on the Most Adorable Horrifying Ecosystem Destroying Plague Ever:
4. Killer bees (Africanized Honey Bees)
Remember when the US lost its collective mind over an impending invasion of enraged Africanized honey-bees? I do (as well as the crappy horror movies the mania spawned, unfortunately).
Killer bees, known to scientists as Africanized honey bees, are crossbreeds between our beloved, fuzzy European worker bees and way more hardcore African bees.
According to the Smithsonian, Brazilian scientists decided to crossbreed the varieties to improve honey production, but found the resulting crossbred bees had a nasty temperament, and attacked with much more ferocity than the European bees. And then they escaped. And headed North.
Among the differences, according to the USDA, Africanized honey bees "swarm" (move house en masse) more often then the milder European variety - and they also will fiercely protect a much larger "home" than their relatives.
The bees first hit the US in 1990, according to Smithsonian, and have been here ever since.
Killer bee mania has faded somewhat in the US since the 1990s, but they still do kill people: in 2010, a 73-year-old man was killed by the insects when he accidentally disturbed their nest with a bulldozer.
WikiHow offers a handy primer on how one best avoids killer bees. Since that comes up so often, you know?
5. European Wild Boar
Huge, fast, aggressive and delicious when braised: that's the feral hog, a distant relative of the pinkish Wilburs you may be more familiar with. According to PBS, these massive beasts were introduced in Florida all the way back in 1539 from their native Eurasian territory by bacon-loving Spanish explorers, and they've been tearing up forests and terrorizing humans ever since.
Boar destroy ecosystems by rooting up native plants and eating food other animals rely on. They're also a pain for farmers, eating sugar cane, corn, and other cashcrops and not responding very nicely to attempts to get them to leave. Mississippi State guesses that wild pigs cause around $1.5 billion in environmental and agriculture damage annually.
On the bright side? Unlike zebra mussels, the oft-hunted (if hard to kill) wild boar tastes delicious. Here, have some recipes! This is one of the few invasive species where eating a delicious roast can be considered a positive step towards conservation.
Here's a video of what appears to be a Burmese python post snacking on a wild boar. Never say I did nothing for you. (There's also this harrowing footage of an incredibly dangerous wild boar approaching a daring camera person, but don't say I didn't warn you).
Is there a single worst invasive species? Not really - they're all pretty bad, says Dionigi, the deputy director of the National Invasive Species Council.
Invasive species "degrade, consume, and displace our crops, farms, gardens, and favorite places," he told GlobalPost. "No area, no matter how cherished, is free from the threat." (Including your own backyard, natch).
"Because of these complex impacts, some of which are only now being understood, it is difficult to identify a single species as the “worst,'' added Dionigi. "However, invasive species are a leading cause of a loss of animal and plant species world-wide."
Invasive species also can be really expensive, added Dionigi - and not just for the federal government.
"The federal government alone spends over $1.5 billion on invasive species prevention and control each year," he said. "However, the bulk of the costs of controlling invasive species fall to states, tribes, local governments, and private land owners."
Think about this if you ever decide your child's irritating exotic pet might just be better off in the wild.