11 Invasive Species Wreaking Havoc on NY

You know when you’re swimming and a slippery rock makes you fall and feel like you broke your tailbone? It’s possible you stepped into glistening invasive ooze commonly referred to as “rock snot.” There are many invasive species that pose threats to our ecosystem here in New York. They are found underwater and on land, can be plants or animals, and in most cases, like in-laws, can be very hard to get rid of (we’re looking at you, Japanese knotweed)! Commonalities include voracious appetites, the ability to wipe out native species, and a serious inability for empathy. Here are 11 of the worst offenders found in New York State. No matter which region you call home, there’s a good chance one is your neighbor.

Check out the DEC’s website for a list of preventive measures to help prevent the spread of common invasive species.

Giant Hogweed

It’s hard to imagine why this plant exists except to punish those who get too close.

The monstrosity originated in the Caucasus Mountains and came to the U.S by way of landscapers who believed it to be a great ornamental garden plant, as well as migrating birds and waterways carrying seeds. The sap from this noxious weed can cause painful blisters and permanent scarring if touched by bare skin, and blindness if you get it in or near your eyes. As Bobby Boucher’s mama says, “it’s the devil!” They can grow up to 20 feet tall and 5 feet in diameter. 

Sea Lamprey

This eel-shaped vacuum cleaner with teeth may be the most hideous fish in New York. They are parasitic, slimy, and attach themselves to their host. Currently, found mainly in the Lake Champlain Basin, they have an affinity for latching onto Atlantic salmon, lake trout, walleye, northern pike, and lake sturgeon, literally sucking the life out of them by draining their fluids through the hicky-like puncture wound it creates. Sea lampreys kill off native fish populations, negatively impacting an economy largely dependent on sport fishing. 

Northern Snakehead Fish

Its name isn’t all that original – it literally has the head of a snake and the body of a fish. Picture that. And now add in spiky teeth, an ability to live on land for up to three days, and bad breath (that last one isn’t scientific, it’s just a guess). 

Considered a delicacy in Asia, hopefully efforts to combat this fish will prevent that from happening here in the U.S. It has a voracious appetite when it comes to other fish, crayfish, frogs, and insects. The snakehead has been found in a couple of ponds in Queens and Ridgebury Lake in Orange County, which provides access to the Hudson River. State efforts at poisoning entire populations have proven successful, although the pesticide they use happens to kill everything else along with it.

Japanese Knotweed

Imagine a visiting in-law…in plant form. Also known as Japanese bamboo, this invasive is really tough to get rid of. These plants create a dense cover that blots out the sun, threatening and wiping out native plants

The hollow stems and wide leaves make it exceptionally resistant to dry or wet weather, and its shallow, tuber-like roots can spread like wildfire. To get rid of it, it’s recommended to use elbow grease and rip them out, roots and all, and dispose of them carefully to prevent re-rooting. Although the young  shoots are actually edible and can be eaten raw, it is not recommended going out of your way to grow an invasive species – rather eat what you find until it’s gone, and cherish the memories. Japanese knotweed has a similar taste to rhubarb, and when harvesting for your dinner plate, take only young shoots about six inches tall. They become very tough and fibrous as they age, kind of like that intruding in-law.

Emerald Ash Borer

Despite the glitzy name, this insect has been killing Ash trees since 2002 and has more than 50 million dead trees in the U.S. to its credit. It literally bores into the bark of an Ash tree and feeds on the tree’s tissues, permanently damaging and killing the tree. Once infected by the EAB, trees typically die within two to four years. Native to China, the EAB most likely came over to the U.S. buried in the cheap and toxic chemical-laden crap we can’t seem to stop buying.

Asian Clam

Not much bigger than a dime, the Asian clam has been a prolific multiplier here in the United States, and can be found in 46 states. This mollusk thrives in many of the Great Lakes and can clog intake valves, such as those for drinking water supplies. Their spread is thought to be attributable to warming waters due to climate change. They have caused millions in damages to water systems, and the cost of removing them every year can cost more than a billion dollars annually in the U.S. They also excrete a nutrient that aids in the growth of algae, and their shells create dense mat of sharp shells that are not conducive to the bare feet of swimmers. Of course Asian clams also compete with native species for food supplies.

Didymo (Rock Snot)

Gesundheit! This microscopic algae’s namesake stems from its thick, brown, and slimy mats that form on stream bottoms – which have ruined many summer swims over the years. It can grow in fast or slow-moving water, last for months, and literally choke out the natural habitat, negatively affecting native plant and fish species. Rock snot has been found in Washington, Saratoga, Delaware, and Ulster counties, and was recently discovered for the first time in a popular western New York trout stream – an odious sign of its spread.

Gypsy Moth

For an invasive, the Gypsy Moth itself isn’t too bad – but just like teenagers, it’s the caterpillar-stage you have to be wary of. These little fuzzy caterpillars enjoy eating the lush vegetation of nearly every single tree in New York – like the oak, apple, crabapple, birch, pine, maple, and more. Not to be confused with the tent caterpillar, Gypsy Moths were brought to the U.S. from France in the hopes of spurring a silk industry. The venture failed, and moths escaped into the wild blue yonder of Massachusetts. From there, they spread. A natural predator has been identified, which is absolutely cuckoo. Seriously, it’s the Cuckoo bird.


We could make terrible Godzilla puns, but there are better ways to make this plant funny without getting too deep into the, ahem, weeds. Found in southern and western New York, Hydrilla roots itself in the bed of a waterbody and can grow more than 20 feet to the surface, creating a dense mat of vegetation that can smother native plants and cause drainage problems. This perennial is thought to have been introduced by the pet fish industry, as it is a popular aquarium plant.  

Spiny Water Flea

The spiny water flea is found mainly in the Great Lakes, and it is thought to have been introduced by international tanker ships from Europe and Asia dumping untreated water. It can grow to more than half an inch long, with its spine making up about 70 percent of its length. And this is no ordinary spine – it has up to three sets of barbs to avoid getting eaten by natural predators like young fish. The spiny water flea competes with native fish, like perch, and mainly eats zooplankton, which many aquatic species are dependent upon. They are also frustrating for recreationalists. For instance, spiny water fleas are known for gumming up fishing lines.

Eurasian Water Milfoil

This pesky plant, native to Europe and Asia, is the most common aquatic invasive plant in New York State. Like many aquatic invasives, it arrived largely from untreated ballast water. 

The low-growing, submerged perennial can be found in all of the state’s watersheds and can grow up to 20 feet long, creating a dense mat of feathery vegetation on the water’s surface. In addition to interfering with water recreation, stagnant mats are a perfect breeding ground for mosquitos. Milfoil also can alter a waterbody’s natural ecology by blocking light and sediment.