Attack of the Pine
Beetles!
 |
| The Red Turpentine beetle is the largest at just 3/8" |
There is currently a noticeable increase in mortality of the
Ponderosa pine trees in the Spokane region.
The reason for this is a marked increase in pine beetle activity,
frequently a result of increased human activity in wooded areas. There are four species of beetles infesting
the pine trees. They are: Ips, Mountain
Pine Beetle, Western Pine Beetle and Red Turpentine Beetle. These insects are quite tiny, ranging in size
from the 1/8” long Ips to the 3/8” long Red Turpentine. All four species of beetle are capable of
killing the trees they infest within one year although the Red Turpentine commonly
attack trees already weakened and are rarely the sole cause of mortality.
The four species emerge at different times during the spring
and early summer, normally May through August though weather conditions
influence the variability of that timing.
Beetle activity can start as early as April and last well into
September. The time of year when the
beetles are most active is also the time of year when people tend to work on
construction projects, pruning, thinning or logging operations. Unfortunately, all of the pine beetles are
attracted by the smell of pitch and will come from several miles away to a
stand of trees where the smell of pitch is present.
Once a tree is wounded and
the bark has been scrapped or cut away on any part of the tree, the beetles can
easily gain access to the exposed inner bark layers and are not susceptible to
the trees defense mechanism of attempting to pitch the insect out. Any timber management activity that would
include cutting or pruning pine trees should be scheduled for fall, winter and
very early spring, extending perhaps into late March if the slash is to be
burned or chipped. Slash piles created
in late winter/early spring are prime beetle breeding habitat.
 |
| Pitch tube indicating beetle attack |
 |
| Piles of sawdust (frass) indicate an attack by the tiny Ips beetle |
Identifying pine beetle infestations is fairly simple if you
know what to look for. Three of the
beetle species will cause the tree to attempt to expel the insect back out the
same hole it bored in through. The
tree’s natural defense against the attack is to “pitch” the insect out,
creating what are called “pitch tubes”.
These can be anywhere from an inch to two inches in diameter. If the tree is fairly healthy, open grown and
has adequate water and nutrients available, it can be successful in warding off
the attack. If however, the tree is
stressed, either by mechanical or other insect damage or disease, or by
overcrowding and a lack of sufficient nutrients or moisture, the beetles will
most likely be successful in getting under the bark and establishing egg
galleries. The tiny Ips beetle leaves
only bits of red/brown sawdust in the cracks of the bark or around the base of
the tree so the attack may be more difficult to recognize. The larval forms of the beetles are what cause
the most damage, destroying the nutrient transporting layers of inner bark.
 |
| Pre-commercial thinning decreases competition for moisture |
 |
| Full scale logging is a good tool if done right |
Pre-commercial thinning or full scale logging can help
prevent an infestation of pine beetle if it is done at the right time of the year. Reducing the stocking rates to what is in
keeping with the amount of moisture and nutrients that are available will help
keep the trees healthy and able to resist disease and insect infestations. The added bonus of removing unhealthy and
overcrowded trees is the reduction of potential hazard fuels should a wildfire
occur in the area. But before picking up the saw and cutting, it would be a
very good idea to contact a forester or do a bit of research. There are a number of publications in the
libraries and on-line about pine beetles and preventing and/or treating
infestations. Your first call should be
to your local conservation district or extension office. In Spokane, contact Garth Davis, Forestry
Program Manager for the Spokane Conservation District at Garth-davis@sccd.org or call 509 535
7274.
