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RED
TURPENTINE BEETLE
(Dendroctonus valens)
Hosts:
Ponderosa pine, lodgepole pine, western white pine, occasionally
spruce and larch
Quick ID:
- Large reddish
pitch tubes on trunk
- Only in
lowermost portion of trunk
- Galleries
short, irregular
- Galleries
packed with frass
- Adult insect
reddish brown, large
 Field
Identification
Tree:
Large (up to 1 1/2"), globular pitch tubes at point of entry,
full of frass (a mixture of sawdust and insect droppings) and reddish.
Galleries of the insect are irregular and packed with frass, varying
between 1/2 and 1" in width and up to several feet in length.
Individual larvae galleries are not constructed; instead, a large
cavity is formed. Galleries are usually found only in the bottom
six feet of the trunk.
Insect:
Adults are reddish-brown and may be 3/8" in length, the largest
of the Dendroctonus bark beetles. Larvae are up to 1/2" in
length, and feed together in a common brood chamber. Pupal chambers
may be found at the base of the host tree.
May be confused
with: Mountain pine beetle.
Life cycle:
Attacks occur through the warm weather and peak in midsummer.
Adult turpentine beetles bore through the outer bark and excavate
short, irregular, longitudinal to cavelike galleries between the
bark and the wood. Eggs are laid in groups packed with frass on
the sides of the gallery. When the eggs hatch, the larvae remain
together and excavate large cavities while feeding. Further development
to pupae and adults takes place in the cavity or in short galleries
along its margin. Larvae and adults overwinter in the tree. Generations
per year varies with climate; in the coldest part of the range,
one generation is produced every two years, while in the warmest
areas, two to three generations may be produced in one year. This
is not one of the most aggressive bark beetles and attacks do not
become epidemic.
Predisposing
factors: Red turpentine beetles commonly attack trees already
weakened by injury, other bark beetle attacks, or disease. Freshly
cut stumps, exposed roots and the lower trunk of declining trees
are all attacked, as are "leave" trees after logging operations
and fire survivors. It is commonly associated with attacks of Ips
or mountain pine beetle, which are usually responsible for the actual
death of the tree.
Impact:
As this bark beetle does not become epidemic, losses are not
as catastrophic as with the mountain or western pine beetles. Occasionally
it kills trees that have been scorched by fire. The Forest Service
puts it in a group with a number of other bark beetles for which
losses in 1990 in Washington ran about 118.9 million cubic feet.
Management:
Silvicultural activities designed to maintain vigorous, fast-growing
stock will help as these trees are more resistant to bark beetle
attack generally. Minimizing injury to "leave" trees during
logging and silvicultural operations will keep the tree from being
weakened. Pruning dead branches is fine, but pruning live branches
opens a wound that may attract turpentine beetles. Bear in mind
that root rot diseases often predispose the tree to bark beetle
attack; search the roots and root collar for signs of infections.
On high value trees near woodland homes or in campgrounds, chemical
sprays may be used to prevent attacks. Lastly, salvage logging of
beetle-killed trees is acceptable providing root rot is not present.
Note:
Use pesticides with care. Apply them only to plants, animals, or
sites listed on label. When mixing and applying pesticides, follow
all label precautions to protect yourself and others around you.
It is a violation of the law to disregard label directions. If pesticides
are spilled on skin or clothing, remove clothing and wash skin thoroughly.
Store pesticides in their original containers and keep them out
of the reach of children, pets and livestock.
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