Hemlock Woolly Adelgids, an invasive insect species originally from East Asia, are not a new problem for West Virginia forests, but they are a significant problem. They have the potential to drastically change the beautiful, diverse West Virginia landscape that we know and love, and while many ecologists are fighting hard to rid the state of this pest, it may be a battle that’s impossible to win.
What’s that, you ask? A dusting of snow on yonder hemlock tree?
USDA Forest Service/Wikimedia
No, unfortunately, it’s not snow. It’s bugs - little hemlock woolly adelgid egg sacs, to be exact - and they’re bad news for West Virginia’s vast stands of beautiful hemlock forests.
Connecticut Agricultural Experiment Station Archive/Wikipedia
You can think of these tiny creatures like aphids, except these guys prey on hemlock trees rather than garden plants.
Beatriz Moisset/Wikipedia While the egg sacs are white, the actual insects are brown, and only about 0.8 millimeters long. They reproduce asexually, up to twice per year, and, at least in the Western United States, only produce females.
The females can then lay 100-300 eggs in the white, woolly sacs on the underside of the hemlock branches each spring. The larvae spread easily from tree to tree by wind and animal carriers.
Michael Montgomery, USDA Forest Service/Wikipedia An infested tree typically only survives 4-10 years after infestation.
What would we lose if hemlocks disappeared from the landscape? Plant diversity (many understory plants thrive in the year-round shade provided by the hemlock), for one.
Bohemian Baltimore/Wikimedia Beauty, for another. The hemlock is an evergreen, providing a cheerful flare of green even in the deepest, darkest days of winter…plus how cute are the little hemlock cones? And since the unique golden hue of the Blackwater River is attributed to tannin from hemlock needles, we even lose this bit of uniqueness. Let’s hope not!
Massive efforts are underway throughout West Virginia to combat this tiny but mighty bug. Beetles have been introduced to feast on woolly adelgids. Insecticide tablets are buried near the roots of hemlock trees (or injected into the bark) to turn the hemlock sap deadly to the voracious little insects.
Jodi French-Burr/NPS
But will these efforts preserve our hemlock forests? Only time will tell.
USDA Forest Service/Wikimedia
Connecticut Agricultural Experiment Station Archive/Wikipedia
Beatriz Moisset/Wikipedia
While the egg sacs are white, the actual insects are brown, and only about 0.8 millimeters long. They reproduce asexually, up to twice per year, and, at least in the Western United States, only produce females.
Michael Montgomery, USDA Forest Service/Wikipedia
An infested tree typically only survives 4-10 years after infestation.
Bohemian Baltimore/Wikimedia
Beauty, for another. The hemlock is an evergreen, providing a cheerful flare of green even in the deepest, darkest days of winter…plus how cute are the little hemlock cones? And since the unique golden hue of the Blackwater River is attributed to tannin from hemlock needles, we even lose this bit of uniqueness. Let’s hope not!
Jodi French-Burr/NPS
To learn more, you can find information on hemlock woolly adelgids in the New River Gorge on the National Park Service website here. Have you ever spotted signs of these destructive creatures in the forest as you hike?
Oh, and to see Blackwater Falls while the water is still “black” (or more golden-amber, actually), check this article for details.
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