Katie Kosanke

Pine Beetles: What You Need to Know

Katie Kosanke, Parks & Recreation, Urban Forester, 509.363.5496

Friday, February 10, 2023 at 4:30 p.m.

Pine Beetles: What You Need to Know

Spokane is known for its ubiquitous Ponderosa Pine – our official city tree. Characterized by their tall and lean stature with long needles and large pinecones, these mighty and majestic conifers can be found just about everywhere you look.

Resilient as they may be in Spokane’s arid climate with its blistering summers and punishing winters, our treasured pines are now at more risk than ever from a hidden killer – the pine beetle.

While there are several varieties of pine beetle, the most notorious in our area are the western pine beetle and pine engraver beetle, sometimes called Ips beetle. These beetles can attack most pine trees but prefer ponderosa.

Damage to the tree occurs as the pine beetle tunnels between the bark and the wood to lay eggs, and the larvae continue tunneling to feed as they grow. The beetles also carry a fungus that can clog the tree’s water transportation system. The ensuing damage prevents water and nutrients from moving throughout the conductive vessels of the tree, eventually leading to death. Older trees or those affected by fire damage, drought, or disease are most vulnerable to pine beetle infestation.

Signs of Pine Beetle Infestation

While much of the damage inflicted by a pine beetle infestation occurs within and underneath the bark, there are a few key symptoms that can be viewed externally:

  • Change of color of all pine needles – typically fading to yellow and then to orange
  • Pitch tubes on the trunk
  • Bark flaking off by woodpeckers which feed on pine beetles, exposing the bright orange inner bark
Prevention and Control

Unfortunately, once an infestation has occurred, the best solution is usually removing the tree as pesticides have no effect on an already infested tree. However, it is important to note that pine beetles are less successful at invading a healthy tree. Thus, taking measures to ensure the best chance for your ponderosa to thrive is critical. Here are a few key tips for keeping your ponderosas healthy and preventing beetle outbreaks:

  • Keep trees watered, especially during drought.
  • Irrigate deep into the soil intermittently to encourage roots to grow deeper.
  • Remove infested trees during the dormant season before beetles emerge (October-February).
  • Remove downed trees and clean up pine debris, especially if it’s not dry promptly before new broods emerge.
  • Do not stack green firewood near live trees.

If you suspect a pine beetle infestation, get a consultation by a qualified professional. You can find a list of certified arborists in our area on our website.

In addition, the following local organizations provide educational information on this topic.

WSU Extension Plant Clinic Direct contact info: mgardener@spokanecounty.org or 509.477.2181, website.

Spokane County Conservation Dist, Forestry Program 509.535.7274

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