Attack of the Pine Beetles!

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.