The forest at Great Smoky Mountains National Park is sick, infected by invasive bugs and
plants. Matt Moore, Kaleb Lique Naitove and
Emily Baird of the National Park Service are
some of the field medics trying to keep it alive.
…
The forest they walk through is mesmerizing. The
trees glow green in the Tennessee sun. There
are a lot of tree species in this forest, but the
one they’re looking to treat is an Eastern
hemlock, an evergreen conifer that ranges
from Canada to northern Mississippi. Hemlocks
make up a significant portion of a lot of forests
in the eastern U. S., but particularly so in Great
Smoky Mountains National Park.
…
‘A Tsunami Wave’ Of Adelgids
After about 20 minutes of hiking off-trail in
the park, Moore and company reach the tree
they’ve been looking for. It’s tall, but not
particularly big. You could wrap your arms
around its trunk and still clasp your hands. By
all outward appearances, it’s healthy.
It’s time for the crew to start helping the tree
by injecting it with pesticide. Moore drills holes
around the tree’s base and then Lique Naitove
and Baird attach tubing. A bicycle pump
connected to the tube system begins to fill
it and then the base of the tree with the red
pesticide.
The female wooly adelgid is miniscule, attaching herself to the hemlock’s needle after creating her ova sack, as
shown above.
To Tame A ‘Wave’ Of Invasive Bugs,
Park Service Introduces Predator
Beetles
by Nathan Rott
Instructional Segment 1 | Authentic Reading
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Copyright © by Savvas Learning Company LLC. ,
It’s called a tree injection system. “We call
them IVs,” Webster says. “They’re out doing
a tree IV.”
It’s like a flu shot that will help the tree ward off
invasive bugs. Most of the trees Webster’s crew
treat just get sprayed with pesticides that have
the same effect. This one’s different because
it’s near a stream and the crew doesn’t want
pesticides getting in the water.
They can’t do it for all of the trees they
treat because there are just too many. The
vegetation crew here has treated more than
a quarter million trees in the Great Smoky
Mountains. The treated ones, like the one they
hiked to, are easy to spot because they look
healthy and are alive. The trees that weren’t
treated are probably dead “or they’re close
or on the way out very soon,” Webster says.
“Probably in the next 10 years.”
The reason for this die-off is the hemlock
woolly adelgid, which is native to Asia.
Scientists believe that the specific kind killing
the Eastern hemlock is from southern Japan.
Adelgids were first discovered in the U. S. in
the 1920s. They were transported overseas
by humans and continue to be spread with
human help, mostly through the purchasing,
selling and transporting of firewood. Today,
the hemlock woolly adelgid is established in
16 states, from Maine to Georgia.
The trees at Great Smoky Mountains National
Park have been infested with adelgids
for longer than a decade. With no natural
predators and no evolved defenses, the
adelgids swept through the hemlocks at the
park like “a tsunami wave,” Webster says.
Many of the park’s hemlocks died quickly;
others are dying more slowly.
…
A Predator-Prey Balance
The pesticide treatment that the park’s
vegetation crew uses doesn’t get rid of the
hemlock woolly adelgid. It protects the tree
that gets it and only lasts five to seven years.
“It’s a stopgap solution,” Webster says.
Because of that, the National Park Service and
scientists have been trying a longer-lasting
one: predator beetles. The hemlock woolly
adelgid, like most invasive species, thrives in
its new environment because it doesn’t have
any natural predators. To change that dynamic,
Great Smoky Mountains National Park has
brought in a few species of predator beetles
from Asia that they’re raising at insectaries, or
nurseries for bugs.
…
Predator beetles will never eradicate the
hemlock woolly adelgid. They’re here to stay.
The hope of the Park Service is that by creating
that balance between predator and prey and
by educating people to not move firewood
from one location to another, they can slow
the spread of the adelgid enough to give
the remaining Eastern hemlocks a chance to
survive and adapt.

READING COMPREHENSION
1. About when were the wooly adelgids introduced to the US and how are they spreading?
2. Describe how the introduction of a predator beetle from Asia might affect the wooly adelgid population.
3. Describe why the hemlock wooly adelgid was able to sweep through the hemlocks of Great Smoky Mountain National Park.
4. Why did the vegetation crew decide to treat the hemlock in the article with a tree IV, instead of using pesticides as they did for other hemlocks?