Great Parks of Hamilton County is managing spotted lanternfly populations by going after another invasive species: tree of heaven, the lanternfly's preferred host.
Trees of heaven provide food and egg-laying space for spotted lanternflies, which have been detected at Great Parks properties since 2023. They also suppress the growth of native plants by producing allelopathic toxins and competing for sunlight and resources, according to a Michigan State University Extension article.
Manager of Urban Forestry Steve Grimm says tree of heaven removal is part of Great Parks’ overall land management strategy.
“Part of our conservation efforts is to promote biodiversity and support native species, which is good for the local ecology and is in line with our goal of encouraging ecological resiliency [and] sustainability,” Grimm said. “So, we go after non-native invasive species like the tree of heaven.”
Great Parks crews manage trees of heaven in a couple ways.
“They either treat it with an herbicide, or they do what's called girdling, where they remove part of the cambium around the tree and treat it with herbicide,” Grimm said. “That'll kill the tree, and then we'll remove it once we know it's dead because it's a prolific root spreader.”
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Grimm stands on a trail at Embshoff Woods in Delhi Township, one of the three Great Parks where spotted lanternflies are known to be. Off the path, the limbs and trunks of tens of cut-down, dead trees of heaven lie on the ground, where they will decompose.
When Grimm checked this section of the woods on a cool October morning, he found one spotted lanternfly and one egg mass, both on living trees of heaven.
“I haven't actually seen them that much in the field in Hamilton County,” Grimm said. “I think part of that is because it's fairly new here.”
Grimm says his level of concern about spotted lanternflies in parks is not as high as about other invasive insects like the emerald ash borer or Asian longhorned beetle, which kill ash, maple and other native trees. Spotted lanternflies can damage trees of heaven and harm crops like grapes.
Grimm says Great Parks is continuing to monitor the invasive insect and remove its invasive host.
Look out for egg masses! And reporting tools
Spotted lanternflies lay their eggs during the fall on flat surfaces, including trees of heaven.
An Ohio State University Extension article describes eggs as being laid “in clusters of 30–50 eggs arranged in 4–7 columns of aligned seed-like eggs.” The columns are about one inch long and covered in a mud-like substance that is light gray, but gets darker with age.
If you see an egg mass, Grimm says to scrape it off and squish it, or put it in a bag of sanitizer.
Spotted lanternfly and egg mass sightings should also be reported to the Ohio Department of Agriculture through the Plant Pest Reporting Tool.