A tiny beetle could help save the Smokies’ hemlocks
Courtesy of the Great Smoky Mountains National Park
In Great Smoky Mountains National Park, a quiet battle is underway – one that could determine the future of our forests. The enemy? The hemlock woolly adelgid (HWA), an invasive insect from Asia that has been killing eastern hemlock trees since it was first detected here in 2002.
Hemlocks are foundational species in the Smokies’ ecosystem. Their dense canopies help keep mountain streams cool, creating ideal habitats for native species like brook trout, salamanders, and aquatic insects. Their roots stabilize soil, reduce erosion, and help maintain clean waterways throughout the park. Tennessee has been particularly impacted in areas of Cades Cove and Kuwohi (Clingmans Dome). But without intervention, eastern hemlocks could face ecological extinction.
What’s being done
Park biologists are using a multi-pronged, integrated approach to fight HWA:
Systemic treatments: Individual trees are treated with a systemic pesticide on a 5-7 year rotation.
Spray treatments: Trees are sprayed annually in high-traffic areas like campgrounds and picnic spots during the off-season.
Biocontrol: The newest and most promising tool in the fight. Laricobius osakensis beetles – tiny beetles native to Japan (where HWA also originates) – feed exclusively on HWA. After years of research and careful approval, they’re now being released at select sites in the park.
Why biocontrol
Unlike chemical treatments, biocontrol offers a long-term, sustainable solution to the HWA problem. These beetles lay their eggs near HWA colonies, and when the larvae hatch, they feed on the adelgids.
Why it matters
Invasive species like HWA disrupt native ecosystems and often lack natural predators. HWA is a major threat to the biodiversity of forests in the Smokies.
This biocontrol effort has the potential to preserve an iconic species and protect the ecological integrity of the park for generations to come.