The Invasive Species Threatening Indy’s Ecosystems

Earth may have yet to endure a War of the Worlds–level invasion, but our ecosystem isn’t so lucky. Here are the species plaguing Indiana and how you can combat them.
Illustrations by Evangeline Gallagher/Indianapolis Monthly

Indiana’s natural spaces aren’t all that natural anymore. Our rivers teem with foreign fish that pose a danger to boaters; innocuous-looking decorative plants have escaped suburban gardens and now multiply unchecked in our forests; and insects capable of wiping out entire tree species have hitchhiked to the Hoosier state on everything from firewood to cargo pallets. Stopping or even slowing the incursions is tough. Battling the complacency surrounding the problem is even tougher. “If caught early, this is something that is imminently preventable,” says Aaron Stump, habitat programs manager for the Indiana Wildlife Federation, “but some species have invaded to the point where we’ll probably never get rid of them. A lot of it is just lack of awareness, lack of information, and, a lot of times, lack of public interest.” The following pages offer just a sample of what’s out there. The complete picture is much bigger.

And more intruders are on the way.


Callery Pear (aka Bradford Pear)

This Asiatic invader’s story reads like the plot of Jurassic Park. Imported from China, the smallish tree became the darling of developers seeking low-maintenance flora to tart up office parks and residential subdivisions. It was originally sterile. But to quote Jeff Goldblum, “Life, uh, finds a way.” To make it less vulnerable to wind damage, it was crossed with other pear varieties, inadvertently producing weedy hybrids that are as fertile as they are fast-spreading.

“If you take a drive down I-69 in March, it looks like a blizzard has come through,” Stump says. “In the forested roadsides, you’ll have all these white flowers from the Callery pears.”

If you’ve got one on your property, cut it down (if the wind hasn’t already dispatched it) and replace it with a serviceberry tree. They’re about the same size and shape as the Callery pear and produce beautiful spring flowers, but they don’t spread aggressively.


This Chinese native was imported to the United States for use as an ornamental ground cover in shady areas. And it certainly excels at that. Unfortunately, it also thrives in pretty much all light and soil conditions. It has colonized our entire state, smothering forest floors, climbing trees, and squeezing out native plant species, including ones that local herbivores eat to survive.

Wintercreeper isn’t the only imported ground cover to run amok. Indiana is also plagued by Vinca minor (aka periwinkle), which looks like wintercreeper and causes the same mayhem. To add insult to injury, people who plant it in their yards hoping it will control weeds are usually sorely disappointed.

“To me, this sort of ground cover just creates a huge maintenance issue,” says Pat Sullivan of Sullivan Hardware & Garden. “Do you know what will grow up right in the middle of it? Weeds and grass.”

Asian Bush Honeysuckle

This all-conquering abomination was supposed to provide cover for wildlife (it doesn’t), help control soil erosion (also no), and serve as a lovely ornamental plant for yards and gardens. Which it sort of did. Unfortunately, it almost immediately escaped those yards and gardens and trampled across the countryside.

Though the most invasive honeysuckle varieties are illegal to sell in Indiana, the damage is already done. Nowadays, you can find them pretty much everywhere, from Broad Ripple alleys to the darkest corners of the Hoosier National Forest. They crowd out native plants, with some varieties even releasing growth-inhibiting chemicals that poison the ground around them.

Asian bush honeysuckles grow so densely they shade out everything on the forest floor, often leaving nothing but bare soil, according to the Invasive Plant Species Assessment Working Group. Unsurprisingly, conservation folks would like you to terminate any specimens of this loathsome interloper you might find on your property.

Poison Hemlock

Illustrations by Evangeline Gallagher/Indianapolis Monthly

For some inscrutable reason, this European plant was peddled in the United States as a fancy garden addition. Its white, delicate flower clusters strongly resemble those of Queen Anne’s lace, but with one rather important difference. Poison hemlock (you’d think the name would have been a tip off) is extremely toxic. So toxic, in fact, that the Greek philosopher Socrates committed suicide by drinking a cup of its juice.

The plant reproduces prolifically via windborne seeds and lurks in every Indiana county. The proper methods for safely disposing of poison hemlock can be rather complicated, so reach out to your county’s Purdue Extension office for advice if you have it on your property. Until then, leave the plant alone and keep pets away from it. From the flowers down to the roots, it’s dangerous to humans and animals. Even prolonged skin contact can make you sick.


Nicknamed “the vine that ate the South,” kudzu was imported from Japan in the late 1800s. Unfortunately, no one seemed to notice (until it was too late) that it grows ridiculously fast and can quickly cover an entire forest in impenetrable, 5-foot- deep piles of matted vines. Now it’s invaded the southern half of Indiana and come within striking range of Indianapolis.

“We’ve been working on eradicating kudzu when we can here in Indiana because we’ve seen all the damage it’s created in the South,” says Megan Abraham, director of the Division of Entomology & Plant Pathology at the Indiana Department of Natural Resources.

Wish them luck, because destroying a heavy infestation can involve anything from controlled burning, to serious herbicide applications, to bulldozing. Weirdly, every part of kudzu, from the roots to the leaves, is safe for human consumption. Their flowers are even used for jams and jellies. But Hoosiers can’t nosh their way out of this problem. Kudzu vines grow roughly a foot a day, making them an all-you-can-eat buffet from hell.


Asian Carp

Illustrations by Evangeline Gallagher/Indianapolis Monthly

The term “Asian carp” is a catchall moniker for four types of carp that made their way to the United States from Asia. All of them breed quickly and outcompete native fish, doing incalculable damage to the ecosystem. They also leap out of the water by the hundreds when startled, potentially hurting unwary water-skiers and anglers.

“Imagine going 20 miles an hour and getting hit by a 50-pound fish,” Stump says. “I hear stories all the time of people being injured this way.” Asian carp have thoroughly infiltrated Indiana’s major rivers, including White River. Recently, experts decided to give them a more palatable name, Copi, in hopes of encouraging anglers to catch and eat them (they’re reportedly quite tasty, if somewhat bony). It’s just one part of a furious, multi-front struggle to keep their teeming hordes from invading and possibly laying waste to the Great Lakes.

Feral Hogs

State law says unequivocally that it’s illegal to import, possess, sell, transport, barter, trade, or release wild pigs in Indiana. But apparently somebody didn’t listen.

“These can be an introduced species, meaning somebody thought, ‘I’d like to go hunting this kind of hog, so I’m going to bring one in and let it go,’” Abraham says. “However, there are also feral pigs that simply wandered away from farms.”

Either way, they take to the Indiana countryside like pigs to slop, rooting around streams and ponds and feasting on corn and soybean crops, baby birds, rabbits, and anything else they can find. So far, they’ve made their homes mostly in Southern Indiana, and the DNR has made progress eradicating them. But since a new horde could be clandestinely imported or trot off a farm tomorrow, constant vigilance is required.

Mute Swans

Illustrations by Evangeline Gallagher/Indianapolis Monthly

Originally brought to this country as ornamental pets of sorts, these highly aggressive birds now prowl Indiana’s wetlands, making a mess of ponds and other waterways with their heavy-handed foraging. They also injure and kill other aquatic birds, along with pets and people.

“During the nesting season and rearing of young, mute swans have been known to aggressively drive off people and pets that enter their territory and have even knocked people from their boats and drowned them,” the DNR reports.

Control programs are in place, but literally thousands of mutes still call Indiana home. In part, this is because they sometimes congregate in out-of-the way places and the people who live nearby either don’t know they’re an invasive species or don’t care. “Maybe somebody’s been feeding those swans,” Abraham says. “Some people love life of all kinds, but their good intentions can make bad things happen.”

Zebra Mussels

This innocuous-looking, roughly dime-sized mollusk with a striped shell (hence
the name) has made it big in America. Or rather, made itself a big problem in America. Originally native to the Black, Azov, and Caspian seas, it likely made its way here in the bilge water of a cargo ship. It’s since pervaded most of the eastern United States’ major waterways, including Indiana’s.

These mussels breed rapidly and are infamous for colonizing the water intake pipes of everything from hydroelectric dams to nuclear power plants (gulp). Even worse, they also attach themselves to the shells of native shellfish and vacuum so many nutrients from the water that there’s little left for less-competitive mollusks to eat. Not much can be done for the areas already infested, so a lot of effort is instead devoted to blocking their further spread. For instance, boat owners plying infected bodies of water are advised to inspect their hulls for stowaways before they move to another lake or river.

Sponge Moth

Illustrations by Evangeline Gallagher/Indianapolis Monthly

Formerly known as the gypsy moth, this Eurasian import is one of the most damaging insect invaders in the United States, infesting numerous tree and shrub varieties but saving its most vicious attacks for oak trees. It has overrun Indiana’s northern portion, where experts have fought in a 30-year holding action to keep it from advancing south. “We’ve set ourselves the goal of keeping it confined to the top third of the state,” Abraham says.

Unfortunately, the sponge moth isn’t the state’s only insect interloper. The emerald ash borer beetle, which lays waste to ash trees, traveled across the state on firewood, infesting all of Indiana’s 92 counties. Then there’s the spotted lanternfly, another tree and bush killer that’s recently shown up in a handful of Indiana locales.