Good Natured: Steps to Kick Invasive Species to the Curb
Over the past couple of weeks, we've established that a) hitchhiking, for humans, is dangerous and not to be encouraged, and b) hitchhiking, for animals and plants, is dangerous too, to the ecosystems where they disembark, and should be discouraged—or better yet, stopped completely. We're taking a look at how to make this latter action happen whenever possible.
I remember visiting a natural area in Wisconsin maybe 15 or so years back—long enough ago that I don't remember exactly where, but recent enough that I can picture the trailhead clearly. Mounted on a low platform, right there next to the welcome sign, was, of all things, a set of boot brushes.
Accustomed to seeing these devices outside of nature centers and other buildings where mud is likely to be tracked in, that WI visit marked the first time I'd ever seen such brushes literally out in the open. A sign explained how visitors could help slow the spread of invasive seeds by giving their footwear a good scrub before proceeding down the trail.
Well, you know what? It seemed to work! Our visit to that area, wherever it was, was in late May, and while I remember seeing mayapples, trout lilies and wild geraniums, I also remember noting a lack of garlic mustard—a nonnative invader with seeds that frequently hitch a ride in the mud on our shoes.
And now, all these years later, there's data to back up that timeworn memory.
Back in 2006, partners in southern Illinois' River to River Cooperative Weed Management began installing what is now more than 50 boot brushes at trailheads throughout the region. In 2020, researchers publicized their analyses of the soil and other debris those brushes swept from boots and other footwear. Among the 39 species of plants growing in that dirt were 14 exotics, including the pernicious invaders garlic mustard and Japanese stiltgrass.
Besides stopping the spread of nonnative plants, brushing off shoes and boots can also help stop the spread of various animal invaders too, including a fairly recent but nonetheless major threat: jumping worms. Sold for use in vermiculture and as fishing bait, they're also known as crazy worms, Alabama jumpers, and snake worms. They first appeared in Illinois in 2015 and are now confirmed in roughly half of our 102 counties.
True to their names, these worrisome annelids thrash vigorously when disturbed. But the really troubling part of their behavior is how they destroy healthy soil. Their systems digest organic matter at a very rapid rate, making it unavailable to other organisms and turning topsoil into grainy, useless bits.
If you notice these signs of jumping worm activity, be sure to clean your footwear as well as your tools before leaving the area. Be sure though to be thorough. The eggs these worms produce are teeny tiny—two are contained in a capsule or “cocoon" the size of a mustard seed—and so are easy to miss.
Because jumping worms (and lots of other creatures, seeds and even pathogens) can hitch a ride in soil, be careful when buying plants, especially at private sales. Experts recommend shaking the soil from the plant, or buying bare-root stock.
You might be seeing a theme emerging here. Cleaning up after ourselves, whether it's our shoes and boots or our tools and other gear—including the tires on our vehicles—is a great way to keep terrestrial invaders from hitching a ride from place to place.
The same, it turns out, is true for aquatic hitchhikers. This wild bunch of troublemakers runs the gamut from plants like hydrilla, Eurasian water milfoil and water hyacinth, to animals like zebra and quagga mussels. Pathogens too.
The website www.stopaquatichitchhikers.org has pages and pages of information on invasive species and how to stop them, but their message can be distilled down to three steps:
- CLEAN off visible aquatic plants, animals and mud from all equipment before leaving water access
- DRAIN watercraft bilge, live well, motor and other water-containing devices, also before leaving and
- DRY everything for at least five days, or wipe with a towel before reuse.
I tell ya, it's a never ending battle. Seems like every time we turn around, a new invasive species has arrived.
The US Geological Survey, part of the Department of the Interior, is responsible for tracking the arrival of introduced species and maintains a list, the US Register of Introduced and Invasive Species, with a current count of 8,657 records (not including Alaska and Hawaii, which have separate lists). Yow!
The RIIS is comprehensive, but in terms of reading material it's pretty dry. For those interested in learning more, the website www.invasive.org is more dynamic, and even has pictures.
Better yet, it gives us reason for hope, with links to many federal, state and local organizations working hard to stem the flow of introduced species. Athough the numbers are still terrifying—the Statistics box on their home page states “65,201 Images of 3,336 Invasive Species"—it's comforting to know that we're not powerless.
Maybe, just maybe, if we each do our part, we can help kick those hitchhikers to the curb!
Pam Otto is the outreach ambassador for the St. Charles Park District. She can be reached at potto@stcparks.org.
