See a worm in your yard? It might be invasive

Comments: by Addy Bink - 05/10/26 9:15 AM ET Comments: Link copied by Addy Bink - 05/10/26 9:15 AM ET Comments: Link copied NOW PLAYING (NEXSTAR) – Earthworms aren t necessarily a surprising sight after a day of rain or while working in a garden. Despite their apparent value, those wriggly wigglers are most likely invasive. Whether or not the worm you re seeing is invasive will depend on where you live and, of course, the species of worm. Places that got glaciated 10,000 years ago, there are very few native earthworms, if any, in those areas, Michael Skvarla, an assistant research professor and head of the Insect Identification Laboratory at Penn State University, told Nexstar. Thousands of years ago, all or part of many northern states – Montana, North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa, Missouri, Wisconsin, Illinois, Indiana, Michigan, Ohio, Kentucky, Pennsylvania, New York, Vermont, New Hampshire, Maine, Massachusetts, Connecticut, Rhode Island, and New Jersey – were covered by glaciers. Those glaciers are said to have mostly killed the native earthworms in these regions. Meanwhile, unglaciated areas can boast dozens of native worm species. Some native earthworms can be found in parts of New York and Pennsylvania, Skvarla said. In Minnesota, however, officials say all of the terrestrial earthworms are non-native, invasive species from Europe and Asia. At least seven of the species found in there are contributing to tree seedling, wildflower, and fern loss in the state s hardwood forests, the Department of Natural Resources reports. If you live in these once glaciated areas, the earthworms you re encountering are more likely to be from Europe, Skvarla said. Early immigrants had to use rocks and dirt as ballast to give their ships enough weight. That ballast was unloaded upon arrival, releasing the surviving worms into the New World. Without the forest management practices that have become common today, the European worms found plenty of leaf litter to feast on, leading to the not great change to nutrient cycling and availability, Skvarla added. Earthworms were also brought into the U.S. for the agricultural economy because of their value to farmers. This did work occasionally, but in other instances, it was detrimental, a 2024 report from Stanford University explained. A study, which included contributions from Stanford researchers, found that more than 70 earthworm species have colonized North America. Does that mean you need to go scorched earth on every worm you see? Not exactly. Those foreign worms have been here for 600 years, and we ve kind of reached an equilibrium with it in many places, Skvarla said. The damage is done, it is what it is. Officials hope we have a better chance to fight against more recent invasive species, like the Asian jumping worms. This species has already been found in California, Colorado, Michigan, Minnesota, Maine, Wisconsin, Iowa, Illinois, Indiana, Tennessee, Ohio, Florida, New Jersey, Kansas, Missouri, Nebraska, Oklahoma, Texas, Louisiana, Kentucky, and New Hampshire. There are some notable differences between the earthworms you re familiar with and these jumping worms. Earthworms will produce roughly 30 to 50 eggs over their 10-year lifespan. Jumping worms lay the same number of eggs in a year. They go from hatching out to full-sized adults to laying all these eggs in a year, said Skvarla. To drive that kind of really fast growth and reproduction, they eat a lot. The Asian jumping worms hunger for leaf litter is much greater than that of the European worms, taking habitats from native species. And, unlike their European counterparts, the poop created by the invasive species from Asia does not reincorporate well back into the soil. Now, all your carbon and all of your nutrients that would have been available to plants suddenly aren t available, Skvarla said. This not only harms native species but also creates a better environment for other invasive species. So you see, in the long term, a change from native tree cover to invasive understory shrubs, which is bad. Asian jumping worms can be equally as harmful in your garden, making it more difficult for plants to grow. It s basically bad news all around when they get introduced, according to Skvarla. Thankfully, jumping worms are easy to identify. If you poke them, they ll jump around and squiggle and literally leap into the air. Unfortunately, they aren t as easy to address. There s no widespread control that works against them, Skvarla said. If you have them in your yard, you can let the grass grow. Since the worms prefer living at the soil surface beneath leaves, Skvarla said they ll cook and die if forced to live in an exposed environment like a lawn. The European earthworms are more beneficial. They turn over the soil and incorporate nutrients. Since these areas are drastically different than, say, the forests these worms first infiltrated, their impact is far less of a conce

See a worm in your yard? It might be invasive

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