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Native to Europe, Asia, Africa and the Middle East.
Introduced as domestic pets by settlers in Canada, early
1600s; transmits encephalitis, transmits food poisoning,
including salmonella; nests contain parasites, droppings
corrode buildings, do $1.1 billion in damage annually.
ro
ck
dove
a k a: Pigeon
INSECTS
Many of New Jersey’s once-majestic
groves of Eastern hemlocks in Morris,
Sussex and Warren counties are now
eerie skeletons, their bare, pale trunks
and limbs standing as evidence of the
devastation wrought by an East Asian
insect called the woolly adelgid, which
sucks the fluid from the base of conifer
needles.
Elsewhere, from Passaic and Bergen
counties to South Jersey, large swaths
of oak trees stand leafless, often visible
along major highways, testimony to the
ruinous foraging habits of yet another
foreign intruder, the Eurasian gypsy
moth.
Few other forms of alien invaders
have left such visible scars across the
state’s forests and fields as the bugs
that have ventured from foreign lands.
Hitching rides in overseas shipping
crates and clinging to transported
firewood, the invaders have grown in
numbers over the years, transforming
the natural landscape.
“There is a significant general decline
in the health of our forest that many
people who are not even foresters have
noticed. You can see it now, with trees
that have half of their crowns dead,”
said Bob Williams, a consulting forester
and member of New Jersey’s Pinelands
Forest Advisory Committee.
The invaders, he said, are com-
pounding a stress already faced by
state’s 2.1 million acres of forest cover
because of habitat destruction, natural
pressures, poor stewardship and even
native pests.
“The trees are already stressed and
weak in some areas, and they (invad-
ers) become a death knell,” said Joseph
Zoltowski, supervising entomologist
with the state Department of Agricul-
ture.
The department’s Beneficial Insect
Laboratory has launched a type of
biological warfare against some of the
bugs, unleashing other insects, fungi
and parasites that act as predators
against the aliens. A tiny army of
helpful creatures are keeping gypsy
moths and woolly adelgids in check.
But they will always be with us, and
the lab is constantly challenged to
enlist new soldiers in the battle as new
threats arise.
“The biggest invader — not yet here,
thank God, but it seems like it will be —
is the emerald ash borer. They can
move 30 miles on their own and if they
reach the northwest area of our state,
they will devastate the ash stands
there. They have no predators or
parasites right now,” Zoltowski said.
As with the Asian longhorned beetle,
the borer is an Asian native that may
have arrived in shipping crates and kills
trees during its larval stage after
emerging from egg sacs and feeding on
the inner bark. But it spreads on it’s
own, much faster and farther than the
longhorned beetle.
Discovered in 2002 in southeastern
Michigan, the bug has destroyed tens of
millions of trees in several Midwest and
Eastern states, including Pennsylvania
and West Virginia. Last year it arrived in
New York, and now threatens to alter
America’s favorite pastime.
The bug is slowly moving toward the
timber coveted as the source for the
famous “Louisville Slugger” and other
Major League Baseball bats.
AQUATIC
Every invasive species should have a
name like “rock snot.”
The moniker bestowed on the foreign
carpet-like algae making its way down the
Delaware River is one way to capture the
public’s attention to the environmental
dangers posed by invasive species, said
wildlife experts. Perceptions of the threat
may become blurred, experts contend,
especially when a commercial or cultural
usefulness develops for an alien intruder
— a problem particularly relevant to
aquatic trespassers creeping into rivers,
lakes, estuaries and coastal waters alike.
“Working with invasive species is mostly
about working with people — and getting
their attention,” said Christy Martin of the
Hawaii Department of Land and Natural
Resources.
Hawaii was the first state, 100 years
ago, to find its freshwater invaded by
Asian Swamp eels, an aggressive foreign
predator that also serves as a culinary
staple in some Asian cultures.
Deliberately stocked by people eager to
establish a wild food source, the eels
arrived in Florida in 1997 by the same
means. Researchers who found the eels
two years ago in Silver Lake in the historic
Camden County town of Gibbsboro
suspect they were stocked there as well.
Gobbling up all manner of aquatic life,
the swamp eel can change its sex to suit
reproduction when populations are low
and also remain burrowed in mud for
weeks without food in times of drought —
all factors that give it an edge as it
competes for domination with native
wildlife.
“Invasive species are problematic
because, once they get here, they become
explosive. They often have no natural
enemies. Other organisms are not looking
for them to eat, making them capable of
spreading very quickly and they can out-
compete native species,” said Michael
Kennish, a research professor at Rutgers
University’s Institute of Marine and
Coastal Sciences.
“Small fish eat zooplankton that feed on
plants, and the bigger fish feed on the
smaller fish. Some fish will only eat other
fish, and when a prolific invader is
introduced, the natural food chain can be
totally short-circuited,” Kennish explained.
Three years ago, it was religious fervor
that prompted the dumping of hundreds
of live Asian frogs and turtles into the
Passaic River. Purchased from an Asian
market, they were set free in a Buddhist
animal release ritual linked to reincarna-
tion and karmic redemption.
“There is a good fish, bad fish issue. For
various reasons some people may value
certain invaders, if we can eat them or sell
them for money. ... The problems they
cause may not be realized until much
later,” said Andrew N. Cohen, director and
founder of the Center for Research on
Aquatic Bio-invasions in California, or
CRAB, which has researched San
Francisco Bay.
The bay is a poster child for an
ecosystem turned upside-down after
hundreds of years of humans accidentally
and intentionally introducing invaders.
Even the substrates and zooplankton are
dominated by foreign species, with the
ecosystem constantly in flux.
New Jersey biologists fear the same
could happen to Eastern coastal waters
and freshwater streams.
Atlantic Coast oyster beds were wiped
out in the 1950s and ’60s by a parasite
known as MSX and continue to be plagued
by another parasite called Dermo. Since
Chinese mitten crabs arrived two years
ago, local biologists have been waiting to
see if they will become the scourge they
have been in Europe, where they have
eroded estuaries. They also have posed an
ecological nightmare in California, where
the crabs have fouled the water and
disrupted fishing for nearly two decades.
PLANTS
It’s not quite the man-eating flower of
“Little Shop of Horrors.”
But the “Giant hogweed” is an invader that
invokes fear. Growing up to 20 feet tall and
brandishing large clusters of white blooms,
the foreign plant has a sap in its hairs and
stem that can cause severe burns, blisters,
dermatitis and pigmented scars lasting
several years.
The plant, which also goes by the more
benign name of “giant cow parsley,” initially
became a nuisance in Britain in the 19th
century after being imported from its native
Russia and central Asia as a novelty to
adorn stylish gardens of the wealthy — and
getting loose.
“Soon they escaped, spreading their seed,
preparing for an onslaught, threatening the
human race,” wrote British musician Peter
Gabriel in the 1971 Genesis song, “The
Return of the Giant Hogweed,” which
envisioned the plant dominating mankind.
Private gardens are again to blame for
wild sproutings in the United States.
Although importation of the plant is now
restricted by federal regulations, Giant
hogweed has been found in Hillsborough
Township and in Mendham Township.
Deliberate, ill-considered introductions of
invasive foreign plants in New Jersey is
why they outnumber, by far, all other genre
of foreign species threatening local flora
and fauna with extinction, said David
Snyder, a botanist with the state’s Natural
Heritage Program.
“The thing with the plants, why there are
so many, is ... Plants have a long history
with people. The colonists who came here
brought plants with them from Europe, and
they’ve been bringing them ever since. That
is why the numbers are so disproportionate
to, for example, the number of invasive
animals,” he explained.
Other invading plants arrived by accident,
as their seeds washed ashore after being
inadvertently sucked up and let loose in the
ballast water of ocean sailing vessels.
Foreign plants now constitute nearly 30
percent of the total flora found in New
Jersey, according to botanists.
To date, 974 non-native plants are known
to be pushing aside and intertwining with
the 2,143 native plant species in the Garden
State. The Invasive Species Council
estimates they now cover hundreds of
thousands of New Jersey acres.
“The impact of many plants were not
known for many years, such as the Norway
maple, a tree that was popular to plant
along curbsides,” Snyder said. “The thing
with it, and species like Japanese barberry,
is they have chemicals they excrete to
essentially poison the soil against native
plant species. It was not until the 1990s
that people started studying these things.”
Biologists and botanists have so far
identified 72 foreign plants known to
threaten the habitat of native mammals,
fish, reptiles, amphibians and even insects.
Yet, deliberate introductions continue.
European loosestrife, a beautiful magenta
flower, continues to be sold in nurseries,
although it has been choking off the region’s
wetlands. While state entomologists have
had some success in keeping the plant in
check by annually unleashing an army of
beetles that literally devour the loosestrife,
the Invasive Species Council has suggested
prohibiting the sale of invasive or potentially
invasive plant species.
Regardless, many invaders are simply
here to stay.
“The real problem species are those like
Japanese stilt grass. ... The plant produces
tons and tons of seeds. You cannot exhaust
the seed bank, and it pushes out native
species, and like many of these species,
they have no predators, no control and they
thrive,” Snyder said.
“The point is to pick our battles. We can’t
get rid of every invasive species, so we
concentrate on the worst ones and while
we may not be able to eradicate even those,
we can take a measured approach, starting
with protections in our most fragile
ecosystems,” said Carl P. Schulze Jr.,
director of the state Department of
Agriculture’s Plant Industry Division.
DERMO
a k a: Perkinsosis
(Left) Caused by a parasite known as Perkinsus
marinus, first identified in the Gulf of Mexico in the
1950s; spread to Long Island and Northeast by
the 1990s, compounded MSX destruction.
OYSTER
DISEASES
MSX
a k a: Multi-nucleate Sphere X
(Above right) Parasite native to Japanese oysters.
Time of introduction unclear; maybe arrived in
ballasts of ocean vessels returning from WWII
in 1940s.
European starling
aka: English starling, common starling
Native to Europe and western Asia. One of the world’s
worst 100 invaders, introduced into New York City’s
Central Park in the 1890s by the Acclimation Society of
North America to introduce birds mentioned in William
Shakespeare’s writings; an agricultural pest numbering
200 million to 300 million, spreads diseases, displaces
native birds.
Nutria
a k a: Coypu
Native to Brazil, Paraguay and Argentia. The furry
rodent may grow to more than 20 pounds, sports
orange teeth and a large, block-shaped head. It’s
one of the world’s worst 100 invaders; introduced in
early 1900s as a potential fur source. Some escaped
or were set free. It destroys coastal wetlands with
its voracious plant eating and tunneling; evicts native
mammals while destroying marshes necessary to
waterfowl, wading birds, crabs and fish.
Feral cat
a k a: House cat, stray cat
Native to Asia. One of the world’s worst 100
invaders; domesticated 10,000 years ago,
introduced by European settlers as pets; stealthy
hunters that prey on small creatures; poses
threats to rare ground nesting and migrating
birds, endangered and threatened amphibians;
also spreads diseases, including rabies and
toxoplasmosis as they interact with wild
creatures.
brown rat
a k a: Norway rat
Native to Asia. Arrived with settlers in 1755, now
an estimated 175 million in the United States,
causing millions of dollars in agricultural and
structural damage, while contaminating crops and
food, restricting plant growth by eating seeds and
transmitting a wide range of diseases.
ASIAN LONGHORNED BEETLE
a k a: Starry sky beetle
Native to China. One of the world’s worst 100
invaders, possibly arrived in Brooklyn first in
1996 through wood packing material from
China; landed in New Jersey in 2003 and
destroyed thousands of trees before the
outbreak was stopped.
MUTE SWAN
a k a: Common swan
Native to Europe and Asia.
Introduced and took hold in
Long Island, N.Y., after being
released in 1912 by people
interested in adorning
waterways; destroys
habitat for other
waterfowl, displaces
colonial waterbirds,
prevents native species
from nesting; one swan
can rip up 20 pounds
of aquatic vegetation
in one day.
HEMLOCK WOOLLY ADELGID
a k a: Hemlock chermid, Hemlock chermes
Native to Japan and China. This small aphid-like
insect strips-bare the conifers, leaving behind
tell-tale egg masses along the needles;
destroyed hemlock stands in northern New
Jersey; some biological controls working against
it; changed forest ecosystems as trees died.
BROWN MARMORATED
stink bug
a k a: Yellow-brown stink bug,
East Asian stink bug
Native to Asia. First found in Allentown, PA,
1996; in Milford, N.J. by 1999, throughout
Mid-Atlantic states by 2000 and New Jersey
by 2005; scars fruit crops and trees through its
feeding; inside homes, bugs emit offensive odor.
JAPANESE WAX SCALE Z
a k a: Tortoise wax scale
Native to Eastern Asia. Brownish, purple, tiny
bugs; infest fruit and flowering plants; a pest of
national concern in the United States; New
Jersey authorities suspect they marked its first
landing recently in Hillsborough, calling it
“dangerously injurious” to trees and shrubs.
japanese stiltgrass
a k a: Asian stiltgrass, Chinese packing grass
Native to Japan, Korea, China, Malaysia and India.
Accidentally introduced in the Southeast in early 1900s
in packing crates carrying Chinese porcelain; germinates
quickly, large seed production, grows in all lighting
situations; pushes out native grasses, native wildlife;
deer prefer not to eat it; changes ecosystems.
ASIAN
SHORE CRAB
a k a: Japanese shore crab
Native to Asia-Pacific region. First found in Townsends
Inlet, Cape May County, by a college biology class in
1988, introduced possibly by the ballast waters of
ocean vessels; has a broad diet, vies for same food as
native crabs, shellfish and other aquatic species .
Drab, carpet-like algae; native to northern regions of
Asia, Europe and Canada. Found in Virginia by 1975,
Northwestern states by 1990s, New York by 2007, upper
Delaware River by 2008, scientists theorize it may be a new,
evolving strain of didymo; covers and changes river ecosystems;
blamed for the collapse of brown trout populations in South
Dakota.
purple loostrife X
a k a: Purple lythrum or rainbow weed. Native
to Europe and Asia. Introduced in late 1800s as
ornamental; still sold at nurseries; one plant
procudes up to 2 million seeds per year; grows in
dense stands, chokes off wet-lands, pushing out
native plants and wildlife.
Native to Asia. This is one of the world’s worst 100 invaders;
introduced through ocean vessel ballast waters; found in Ontario
by 1965, California by 1992, Atlantic Coast by 2005 and in New
Jersey by 2008; competes with native crabs and marine life,
may prey on native wildlife.
giant hogweed
a k a: Giant cow parsely
Native to Russia and Asia. Introduced circa 1917 as an
ornamental plant for gardens; grows up to 20 feet in
overturned soils, produces sap that causes blisters and
severe burns to humans, may cause scarring .
japanese
bittersweet
a k a: Oriental bittersweet
Native to China and East Asia. Introduced in 1860s as
ornamental plant and later for highway landscaping;
prolific growth, encircles native trees and covers lower
vegetation, shading out other plants and eventually killing
large trees.
JAPANESE barberry
a k a: Red barberry and Thunberg’s
Barberry. Native to eastern Asia. Introduced
in 1860s as an ornamental plant; will shade
out and push out native plants; raises soil pH
to prevent other plants from growing; birds
help it spread by eating its berries, deer will
not eat it; resilient, growing in shaded woods,
open fields and wetlands.
MULTIFLORA ROSE
a k a Japanese Rose
Native to Asia. Introduced in 1860s as an
ornamental plant; misguidedly planted for
erosion control and natural fencing in the
1900s; resilient and fast growing, forms
dense thickets that kill diversity by pushing
out native plants and the creatures relying
on those native species
TREE OF HEAVEN
a k a: Ailanthus, Tree
from hell, Ghetto palm
Native to China. Intro-
duced in the late 1700s as
an ornamental, later planted
along roadsides; spreads
aggressively; displaces native plants.
japanese
honeysuckle
a k a: Chinese honeysuckle
Native to East Asia. Introduced in 1806 in Long Island,
N.Y., as an ornamental plant; used for erosion control and
widely planted around homes; fast growing; invades many
habitats, covering forest floors, wetlands and roadsides;
strangles native saplings and forms mats in tree canopies,
shutting out light for plants below.
Chinese silvergrass
a k a Zebra grass
Native to Korea, Japan and China.
Iintroduced in the late 1800s, still sold as
an ornamental; forms large clumps,
pushing out native plants; resilient and
tends to grow on overturned soils and
roadsides where it increases
fire risks because it is
extremely flammable.
EUROPEAN GREEN CRAB
a k a: Shore crab
Native to North and Baltic seas. Introduced 150 years
ago possibly by ballast waters in ocean vessels; now
common from Cape Cod to Maryland; wiped-out
softshell clam industry in Maine, impacted Massachu-
setts scallops because it feeds on young of native
shellfish; impacts shorebirds by competing for food and
hosting marine worms that sicken the birds.
CHINES
E
M
ITTEN CRAB
ROCK
SN
OT
a k a: Hairy crab
a k a: Didymo
Some arrived through shipping crates or in the
ballast water of ocean vessels. Others creeped in on
their own or were misguidedly released on purpose.
Our landscape is under attack by an army of foreign
bugs, plants, animals and acquatic creatures —
and more are about to land.
By Brian T. Murray • Star-Ledger Staff
Illustrations by Frank Cecala and Tim Sparvero
JAP
A
NESE BEETLE
Native to northern China, Japan and far east Russia. Appeared in
North America near Riverton, N.J., in 1916; arrived as grubs in
nursery plant soil from Japan, spread by 2000 throughout Eastern
United States, serious plant and crop pest, juveniles feed on seeds
and root; adults feed on leaves, flowers and fruits.
a k a: Popillia japonica
Native to Europe and Mississippi River basin. Grows to 100 pounds;
voracious feeder; spotted in New Jersey in the Delaware & Raritan
Canal, Lambertville, July 1999; hinders striped bass restoration in
the Delaware Estuary; preys on young American eels, sturgeon and
shad and other native freshwater fish.
flath
ead catfish
a k a: None
feral hog Z
aka: Wild pig, Razorback
Native to Europe and Asia. One of the world’s worst
100 invaders, introduced when Spanish explorers
turned domestic pigs loose; farm escapes and
releases suspected in New Jersey, around 1990;
highly adaptive, destroy ecosystems by rooting,
forage on everything; pose health risks to humans
and livestock.
Mile-a-minute vine
a k a: Devil’s tearthumb, Chinese creep
Native to Asia. One of the world’s worst 100 invaders,
introduced repeatedly after 1890s; took hold 1930s and
1940s in York County, Pa. at a nursery; spread 300 miles
away by the 1990s; the trailing vine, bearing downward-
pointing barbs, grows rapidly over native plants and trees,
blocking the sun and preventing regrowth of native forests.
GYPSY MOTH
a k a: Dancing moth
Native to Europe, Asian strain also in North
America. One of the world’s worst 100 invaders;
European strain is the worst hardwood defoliator
in New Jersey; released in 1860s in Massachusetts
after biologist tried to crossbreed them with silk
worms; 1981 outbreak in Northeast defoliated 15
million acres of trees, 800,000 acres in New Jersey.
asian swamp eel
Native to Asia, the snake-like fish is a voracious
predator, devouring native fish, reptiles and
amphibians. It can feed out of water, survive in dried
ponds and thrive in fresh or brackish waters. A
common food source in Asia, the eel was introduced
to Hawaii by immigrants 100 years ago, which also
is how they may have invaded Silver Lake in
Gibbsboro in 2008.
ASIAN TIGER MOSQUITO
a k a: Forest day mosquito
Native to Southeast Asia, China and Japan.
One of the world’s worst 100 invaders,
spread through international tire trade,
aggressive in biting human hosts, transmits
diseases including West Nile , detected in
1985 in Texas, reached New Jersey by 1995.
EURO
P
EAN SPARROW
Native to Middle East, Eurasia. Deliberately introduced in 1800s,
New York City. More than 150 million now; major agricultural
pest, consumes and fouls livestock feed, grain fields and storage
bins; highly aggressive, beating bluebirds, purple martins and
other native birds to preferred nesting site; prone to attack
nests, eggs and nestlings of other species.
a k a: English sparrow
Northern Snakehead
a k a: “Fishzilla,” Snakehead fish,
Amur or Ocellated snakehead
Native to Russian, China and Korea. Grows nearly
3 feet long; voracious predator, sharp teeth, grunts
like a pig while devouring prey, crawls on land, lives
out of water for up to four days, withstands freezing
temperatures; first found in a Maryland pond in
2002.
Eurasian water milfoil Z
aka: Spike water-milfoil
Native to Asia, Europe, Africa. Forms dense
infestations in ponds and slow-moving water
bodies; chokes off diversity; grows to 30 feet
long, supports fewer insects for native fish,
reduces oxygen levels; accidentally and
intentionally introduced between late 1800s
and 1940s.
MAMMALS
& BIRDS
Among the most destructive invaders,
some are familiar — so familiar and deeply
entrenched that people are surprised and
even unwilling to accept that scientists
universally condemn them. One such
species is feral cats. Another is feral pigs.
The International Union for Conservation
of Nature lists both among their “One
Hundred of the World’s Worst Invasive
Alien Species” — an impressive ranking
given the thousands of alien invaders
plaguing the world. The cats, along with
wild or feral pigs, earn that ranking for two
reasons: their destruction of habitat and
their impact on ground nesting birds,
among other creatures, is unmistakable,
agree international, national and local
wildlife authorities.
In 2008 New Jersey wildlife biologists
acknowledged what local hunters, farmers
and property owners in Gloucester County
had known for 20 years. Domestic hogs that
were either set loose or which escaped
from livestock farms decades earlier had
begun breeding in the wild, forming
sounders of up to 100 hogs that were
rooting up forests and fields.
“They revert to a kind of primal state
when they begin feeding on the land,” said
Lawrence Herrighty, assistant director of
the state Division of Fish and Wildlife,
explaining that “Sus scrofa” have a uncanny
ability to adapt to the wild, growing tusks
and turning dark, hairy, lean and mean as
they eat wild foods.
“We allowed a hunt and more than 100
were killed in the first year. ... This past
season, 16 pigs were shot,” said Herrighty
of a control effort launched in 2008. “We
hope to knock out this population. But it’s
not easy.”
Sows can begin breeding at 6 months old,
biologists explained, as well as produce up
to four litters per year in optimal conditions
and turn out four to a dozen piglets each
time.
Cats are equally prolific at breeding. But
no one in New Jersey is proposing a hunt
for the felines, which have no
shortage of defenders. Domesti-
cated in the eastern Mediterra-
nean about 3,000 years ago, cats
have followed humans around the globe,
becoming one of the most lethal invaders
by wiping out birds, small mammals and
other creatures, according to the IUCN.
Decades of research attributed the decline
of many bird species, particularly in South
Pacific islands, to cat predation.
“No other alien predator has had such a
universally damaging effect,” wrote noted
researchers and authors, P.J. Moors and I.
A.E Atkinson, in a 1984 technical publica-
tion for the International Council for Bird
Preservation, now known as BirdLife
International.
The American Bird Conservancy
contends feral and domestic cats annually
kill an estimated 500 million birds in North
America annually, many of them rare
ground nesters. Feline diseases also are a
concern. Topxoplasmosis, a disease related
to a parasite harbored in cat intestines, was
ruled by biologists to be the cause last
summer in the deaths of several gray
squirrels and a bear cub in West Milford.
But animal rights organizations,
including Alley Cat Allies, the American
Society for the Prevention of Cruelty to
Animals and the New Jersey Animal Rights
Alliance, adamantly oppose collecting and
killing strays — and dispute the impact cats
have on wildlife. “They’re not wild, and
they’re not meant to be in the wild and
there are consequences to having them out
there. ... Cats simply are an exotic, non-
native species that present a significant
threat to native wildlife,” said Len Wolgast,
a retired wildlife biology professor at
Rutgers University and former Fish and
Game Council member.
GARDEN
STATE
INVADERS