The United States Department of Agriculture estimates that over 50,000 animal and plant species have been introduced to North America from other countries. They are called invasive species because North America was not their native range and they were all introduced here. While introduction of many of the animals and plants were limited or accidental releases with no known harm to the environment, a few have established breeding populations and are here to stay. They also are highly destructive.
Here is a list of the top 10 invasive species which have established a home and breeding population within Pennsylvania:
1) The Bighead and Silver Carp: A highly invasive species introduced into the United States to control algae from Asia. It can exceed 40 pounds and has established itself in the Mississippi River system and all tributaries including the Ohio River system. This fish competes with other native fish species and reduces the food available for those. It is considered a game fish in some areas.
2) The Black and Brown Rat: Introduced into the United States through shipping transports in the Middle Ages, the Brown and Black Rat are very common in Pennsylvania and is the primary rodent found in large urban areas. Also known as the Sewer Rat. A host to numerous human pathogens including Q Fever. The Brown Rat is the most successful animal species in the world and can be found on every continent except Antarctica.
3) Asian Tiger Mosquito: This insect can be easily identified by its black and white stripped legs and its favorite source of food is humans. Originally found in Southeast Asia, this mosquito is now firmly established in the United States through the transport of goods. The Asian Tiger Mosquito is common in Pennsylvania during the summer months and can often be found feeding in early morning or late afternoon hours. This mosquito can be host to some of the most deadly diseases known to man including Yellow Fever, West Nile Virus and Dengue Fever.
4) Zebra Mussels: Their native range is the Black Sea. This mollusk is suspected to have been introduced to the Great Lakes through ballast dumping from ships and was first discovered in the United States in 1988. Now firmly established and rapidly spreading through the Great Lakes and its tributaries. It can be found in the Mississippi, Ohio and Arkansas River systems and will attach itself to anything solid. They can clog water irrigation systems and treatment plant intakes.
5) Asian Lady Beetle: Another Asia native insect which looks like its cousin the lady bug. Only this insect packs a bite. First introduced to control aphid populations on fruit trees, this common Pennsylvania insect swarms homes in preparation for winter and can be found in populations exceeding thousands on some homes in late fall.
6) Japanese Beetle: This large insect, native to Japan, can be easily identified by its perpetually confused flying pattern and green shell. Common in the summer months, this insect was first discovered in 1916 near a New Jersey nursery. This beetle feeds on numerous native plants including roses and Asparagus in Pennsylvania.
7) Emerald Ash Borer: As the name suggests, this bright green insect feeds exclusively on Ash Trees and has spread to 13 states including Pennsylvania since its first discovery inside the United States in 1990. A native to Asia, some scientists suspect it may eventually spread throughout the nation and destroy all Ash trees in North America. The Ash Borer is transported from location to location through firewood shipments across state lines.
8) Brown Marmorated Stinkbug: A native to China, Japan and Korea, it was accidentally introduced into the United States through overseas shipping. First discovered in Allentown, PA in 1998, it has since spread throughout the state. It is considered an agricultural hazard because it feeds on fruit trees. It can invade homes in swarms during late fall.
9) Northern Snakehead Fish: Originally found in China and Russia, this fish has been discovered in the Potomac River system and its tributaries. This fish threatens native fish species by consuming the same food resources. First discovered in Maryland in 2002, an established breeding population was identified in the Potomac River in 2004. While several fish have been caught in Pennsylvania, it is unknown if an established breeding population exists in the state.
10) Red Fire Ant: First discovered in Mobile, AL in the 1930s, this ant species rapidly adjusted to the warm and humid climate of the Southeast United States and began spreading. By 2012, its range approached the Maryland and Pennsylvania state line and it is unknown how much further north the ants can spread because of cooler climates. This ant is native to South America and is a hazard to humans and pets alike. It leaves a painful bite and creates large dirt mounds which can become home to thousands of individual insects.
The United States Fish and Wildlife Service maintains a website that you can use to find out how you can help control the spread of invasive species.
