Illinois Under Siege: Experts Discuss Invasive Species Threats

URBANA, Ill. – Fig buttercup may have an innocent-sounding name, but it is anything but sweet. The small yellow flowering plant creeps across forest floors, crowding out native spring ephemerals and other understory plants. Try to pull it out, and you are more likely than not to leave its fleshy tubers in the soil, where they lie in wait for the right moment to resprout. And now, fig buttercup is in Illinois.

Chris Evans, forestry extension and research specialist with University of Illinois Extension, says that fig buttercup and another aggressive understory invader, Japanese chaff flower, are looking like the next big threats to Illinois forests. They join common buckthorn, bush honeysuckle, Japanese stiltgrass, and garlic mustard as the state’s top plant pests.

Evans and Eric Larson, assistant professor in the Department of Natural Resources and Environmental Sciences at U of I, recently answered questions in a public Twitter chat and podcast about the threat of invasive species in Illinois. They stressed that being non-native is not enough to render a species invasive – it needs to cause some sort of harm to the environment or community it inhabits. Unfortunately, there are plenty of examples of harmful invaders in the state, in nearly every habitat type.

Larson’s research focuses on invaders of freshwater ecosystems. He ranks silver and bighead carp, zebra mussels, and Asian clams as the top freshwater invaders in Illinois. He’s keeping his eye on emerging threats, too, using modern molecular methods and predictive models to anticipate where new species could get a foothold in the Great Lakes. For example, in a recent study, Larson proved that hidden invaders such as rusty crayfish could be detected from bits of their DNA floating in lake water samples.

Many small, less-obvious organisms also threaten natural resources. “Some of our worst invaders are insects and pathogens that have completely removed foundational tree species. For example, emerald ash borer is in the process of completely removing ash trees from our ecosystems in Illinois,” Evans says.

Invasive species do not just make life harder for native plants and wildlife; they are expensive to control. Evans says the costs to control forest invaders range from $100 to $1,000 per acre, depending on the species, the degree of infestation, and the surrounding environment.

“The most cost effective thing we can do is prevent new invasions from happening, and try to contain the spread of invaders,” Larson says. “In fresh waters, that means being really conscientious about cleaning, draining, and drying your fishing gear and boats before you move between waters, and not releasing live bait in the water. These steps are going to protect our waters, our ecosystems, and save costs down the road from trying to manage these species.”

Evans adds, “Most people now understand the concept of invasive species. What they choose to put in their homes and landscaping has an impact. Everybody has a role to play.”

For more information, listen to the podcast with Larson and Evans at

Sources: Chris Evans, 618-695-3383,; Eric Larson, 217-300-3197,
Writer: Lauren Quinn, 217-300-2435,

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