Blue Ridge Country - September/October 2018 - 61

Story and photos by BRUCE INGRAM

he beetles are doing their job,"
says Carrie Jubb, insect mass rearing supervisor for Virginia Tech's
Department of Entomology, as
she scans the needles of an Eastern hemlock. Jubb, Tom McAvoy,
research entomologist for the department, and I are standing in a hemlock
grove at the university's Kentland Farm
test forest, near Blacksburg, Virginia.
Jubb's praise for a creature about the
size of a large period is well justified and
shows that the labor of her, McAvoy and
others in Tech's Department of Entomology has been well worth the time and
effort. For the dead creatures that we are
examining are the infamous hemlock
woolly adelgids (HWA) that have ravished
the Blue Ridge's hemlocks for several decades now.
Some backstory is required. In the early
1950s, the HWA was first detected in Richmond, Virginia although it is quite likely
this Asian invasive insect had been present in our region before then. At first, its
spread was slow as two decades passed
before the creature appeared somewhere
else-Rocky Mount, Virginia.
"But then the HWA just took off," says
McAvoy. "Once it arrived in the Blue Ridge
Mountains in the 1980s, the adelgid went
north first, then headed south, especially
devastating the hemlocks in the Smoky
Mountains. In parts of the Blue Ridge, 100
percent of the hemlocks have died, in others, 20 to over 90 percent have died."
It is the female of the species that does
the damage to Eastern and Carolina hemlocks, the two species that live in our region. The insects suck the tree's life-giving
sap, and in the process hide themselves
and their eggs in white woolly masses on
the needles. The trees typically decline in
health for a few years after that, but then
rebound by sending out new growth. It is
then that the HWA returns in force, this
time often causing the tree to critically
weaken even more.

RIGHT: This is
what healthy hemlock
needles look like. This
sapling grows in the
shadows of a tree that
has been treated by
Adventures on the
Gorge.
LEFT: NPS service
biologist John Perez
notes the condition of
a hemlock that staff
members have treated
in the New River Gorge
National River.

The insects suck the tree's
life-giving sap, and in the
process hide themselves and
their eggs in white woolly
masses on the needles.
"After a few cycles of that," continues
McAvoy, "many trees die. Some may take
four or five years to succumb, others 20,
and some do not die, especially if they
live in the open and have good soil and
receive lots of sunlight. Trees that live
further north and at higher elevations often have the best chance of survival. But
global warming is changing that as temperatures will increase even faster in the
northern latitudes, causing HWA to spread
even faster and survive at a greater rate."
Which brings us to why Jubb has lauded an insect, because the creature that has
killed the HWA on that Eastern hemlock
is Loricobius nigrinus, a beetle native to the

west coast. For over 15 years as part of a
U.S. Forest Service grant, Tech entomologists (Jubb and McAvoy among them)
have travelled to west coast mountains
to gather L. nigrinus, rear them and their
offspring in a university lab, then ship
these predators to various national forest
home offices across our region. Of course,
this entire process began only after Tech
entomologists and others determined that
releasing L. nigrinus would not cause harm
to any native species.
Next, Jubb shows me a hemlock branch
that has been enveloped in a bag so that
the L. nigrinus could not reach the HWA
feasting on the tree. Of course, that bag

SEPTEMBER/OCTOBER 2018

Blue Ridge Country - September/October 2018

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