For a few years, foragers and fungi enthusiasts around the Midwest have been seeing something yellow.

The butter-colored flushes of the golden oyster mushroom are difficult to miss. They bloom on dead or decaying trees, and they have become profuse in states around the Great Lakes.

The fungi, which are native to Asia, are good to eat and easy to grow. But a new study shows that they may also be sapping the resources of native mushrooms. And their footprint is spreading fast.

“I don’t think anyone would hesitate to call it invasive,” said Aishwarya Veerabahu, a mycologist and doctoral student at the University of Wisconsin-Madison and an author of the study, published Wednesday in the journal Current Biology.

She and her colleagues call the golden oyster “a literal and figurative bright yellow warning” in the study, adding that “as of now, there are no management strategies available to control its spread.”

The mushrooms were almost certainly introduced to the United States by humans, Ms. Veerabahu said. Golden oyster mushrooms and growing kits for them are sold in stores, and the fungus may have spread from backyards or compost piles.

It has been more than a decade since golden oysters were first spotted blooming wild in Midwestern forests. But in the past five years, “It’s just been popping up like crazy all over the place,” said Matthew P. Nelsen, a mycologist and senior research scientist at the Field Museum of Natural History in Chicago.

The apparent dominance of the golden mushroom, as outlined in the study, “paints a troubling picture of what this means for the diversity of wood-rotting fungi,” added Dr. Nelsen, who was not involved in the research, “and all the other organisms that rely on these fungi.”

To investigate the mushrooms, the study authors examined 78 samples of wood drilled from 26 dead elm trees — which make a hospitable environment for the golden oyster — in Wisconsin in the summer of 2022. Of those trees, 15 had become hosts for the fungi.

Those trees that had the golden oyster tended to host about half as many other mushroom species as those that did not. In other words, the golden oyster seemed to hurt fungal biodiversity.

The species may also affect other kinds of life.

It is too soon to say whether the golden oyster causes decaying trees to fall faster, but Michelle Jusino, another study author who studied the mushroom while working with the U.S. Forest Service, said that “when this fungus gets into a tree and you start to see it making a mushroom, the tree seems to have very little time to stay standing on the landscape.”

The correlation could spell bad news for plants and animals who build their lives around old trunks, added Dr. Jusino, who will soon join the University of Florida as a forest pathologist.

While the study relied on samples from Wisconsin, the research has been aided by amateur foragers farther afield. Many report their findings on apps like iNaturalist and Mushroom Observer. As of last month, the golden oyster mushroom has been spotted in the wild in states far from the Great Lakes, like Alabama, Colorado and Texas.

Climate change could propel the species even farther. The researchers said that changing weather patterns were likely to make more of North America habitable for the mushroom, and that the success of the golden oyster was likely to sap resources for native species of fungi.

Alan Bergo, a chef and author in Minnesota who specializes in foraged food, has been watching the golden oyster mushrooms proliferate. “When you see them, it’s awe-inspiring in a scary way,” he said.

But for people who forage and are properly trained in mushroom identification, he said, the fungi are easy to identify and safe to eat. And the best clusters — not too mature, and not too bug-bitten — can be delicious. “They have this meaty, umami, nutty quality to them,” Mr. Bergo said. He likes to prepare them with thyme and butter, and maybe some garlic.

During their field work, the study authors saw people harvesting big bags of the yellow fungi. Ms. Veerabahu, too, has enjoyed the mushrooms in tacos, and Dr. Jusino has cooked them into omelets. (She calls them GOMelets, a portmanteau born of the acronym for golden oyster mushrooms.)

But at this point, both researchers have grown tired of the taste. “Aishwarya and I have both smelled this thing too much to find it to be enticing anymore,” Dr. Jusino said.