Hi I'm Jessie Moan with the University of Alaska Fairbanks Cooperative
Extension Service's Integrated Pest Management Program. This video will guide
you through what to look for if you think you might have spruce beetles in
your trees and a couple of things that you can do if you confirm an infestation.
Spruce beetles are native in Alaska and while they are always present, they are
not always causing notable damage. However, under the right conditions, they
can be serious pests in both our forests and in your landscape and ornamental
trees. Spruce beetle adults are small cylindrical beetles that are
approximately 1/4 inch long and 1/8 of an inch wide. They can range in color
from dark reddish brown to black. Spruce beetles spend the majority of their
lives under the bark of trees, where they feed on the tissue that transports
sugars created in the needles during photosynthesis to other parts of the
tree for energy. Damage in this tissue prevents the tree from being able to feed itself.
If you are concerned about spruce beetle on your property or feel
like your spruce is not thriving as it once has, there are several things to
check for. One of the first things to look for is boring dust. As adult beetles
begin to attack a tree and bore into the bark, sawdust like boring dust is created.
This reddish-brown dust collects in cracks and crevices of the bark and
around the base of the tree. Boring dust is most likely to be seen
relatively soon after an attack.
Pitch tubes are another early sign of sprucebeetle attack. A tree's response to an injury such as a beetle attack,
is to produce excess pitch. This excess pitch mixes with boring dust, creating pitch
tubes around beetle attack sites along the outside of the trunk of the tree.
If you inspect the pitch tubes closely, you may find a small hole through the center
approximately 1/8 of an inch in diameter. Pitch tubes can range in size, but are
usually between dime or nickel size and are usually reddish-brown in color.
Pitch tubes can usually be found during the first year of a spruce beetle attack.
Increased woodpecker activity may occur after a spruce beetle infestation.
Woodpeckers will flake off the bark to get at the beetles living under it. This
is usually most notable in the winter when the bark accumulates on top
the snow. Needle discoloration does not usually occur until the second spring or
summer after a spruce beetle attack. As the tree declines, needles change from
green to yellow to red before falling off the tree. You might not see all of
these signs and symptoms on your tree and sometimes trees don't respond the
way we expect them to. During times of drought stress, a tree might not produce
enough pitch to create pitch tubes. Or if beetle attacks are severe, the needles
might not change color before falling off the tree. Keep that in mind when
assessing your tree and note any substantial changes in tree health.
Management options will vary depending on the specific circumstances of your
infestation but generally you may want to consider removing the infested trees,
spraying uninvested trees with a registered insecticide, and maintaining
the health and vigor of uninvested trees with good tree care practices such as
supplemental watering and fertilizing.
Spruce beetles can be detrimental to your trees, but knowing what to look for can help identify
an infestation early so that you can protect the health of other trees. For more information on
spruce beetles and spruce beetle management in your landscape trees,
contact the Integrated Pest Management Program with Cooperative Extension or
view our publications online. If you have questions about spruce beetle management
and forests, contact the Forest Health Program with the Alaska Department of
Natural Resources, Division of Forestry.