Alien Wildlife Is On The Move – Invasive Species

From Time Magazine July 28, 2014 issue, Written by Bryan Walsh

Global Swarming

The aliens are already here.  Some 50,000 alien species have invaded the United States-and thanks to increasing global trade and the effects of climate change, that number keeps rising.  Many invasive species can find a niche in a new environment without wreaking havoc, and some have even proven beneficial.  But there are other plants and animals that seem determined to displace as many native species as they can while causing considerable economic damage along the way. 

Emerald Ash Borer

Origin Asian and eastern Russia – Invaded territory Much of the Midwest and parts of the Northeast. How it Arrived – Accidentally carried into the United States in wood-packing material from Asia. Threats – In its larval stage the insect bores holes in trees, eventually killing them; more than 8 billion ash trees are at risk.

Snakehead Fish

Origin Africa and Asia, Invaded territory California, Virginia, Florida, Hawaii, Maine, Maryland, Massachusetts, Rhode Island. How it arrived arrived Introduced by fish importers. ThreatsAs a top-line predator, it competes with native fish for food and habitat

Cuban Tree Frog

Origin Caribbean Invaded Territory Hawaii and Florida, How it Arrived  Likely arrived as a hitchhiker on seagoing ships. Threats The largest tree frog in the United States, it eats native frogs and lizards wherever it invades.

Zebra Mussel

Origin  Southern Russia Invaded territory – The Great Lakes and rivers throughout North America  How it arrived – Carried to the Great Lakes in the ballast water used by ocean going ships, the mussels spread beyond the Great Lakes by attaching themselves to the bottoms of boats as they moved from river to river.  Threats  It outcompetes native species for food and can grow so rapidly that it clogs water intake pipes for power plants and other facilities; large power plants spend some $800,000 a year to monitor and control it.

Feral Hog

Origin Eurasia – Invaded territory – Texas, California, Florida, Oklahoma, and throughout the South. How it arrived – Introduced in the 1930’s and released into the wild for hunting, the hog bred with existing pigs to create a feral subspecies that has proliferated in recent years. Threats – It tears out native vegetation and can trample crops while sometimes preying on native wildlife.  It causes $1.5 billion in damage-and-control costs annually.

Asian Carp

Origin Southeast Asia – Invaded territory – Mississippi, Missouri and Illinois river systems, up to Chicago and possibly into the Great Lakes.  How it arrived– Imported in the 1960’s and 1970’s by fish farmers.  It escaped via flooding and proliferated throughout the rivers of the Midwest.  Threats – The Asian carp is a voracious filter feeder and will compete with native marine life for food, costing the region $200 million a year.  One variety the silver carp, leaps into the air when it hears a motor, threatening boaters.


Origin Indo-Pacific Ocean – Invaded territory- Atlantic coastal waters, North Carolina to Florida  How it arrived – Likely brought over in aquariam trade before being discarded. Threats – A tireless predator and rapid breeder, it is capable of wiping out native species around coral reefs.

Asian Long Horned Beetle

Origin Eastern China, Japan and Korea Invaded territory- Northeastern United States – How it arrived – Spread from Asia in wood used in packing material. Threats – Larvae tunnel into trees as they develop, damaging them when they exit as adults; over time, infestations can kill trees directly or make them vulnerable to other treats.

Giant African Snail

Origin East Africa – Invaded territory – Florida- How it arrived- May have hitched a ride aboard passenger luggage into Miami or been brought in as pets.  Threats  It can grow up to 8 inches [20cm] long, eat more than 500 kinds of plants and consume a rnage of materials- including stucco.  It also carries a parasite that can cause meningitis in humans.

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