Five Facts: Pine Engraver Beetles

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Article by, Nicole Sanchez,
Horticulture, OSU Extension Service, Klamath County

Numerous recent inquiries to the Klamath Extension office have involved concerns with pine trees. Most often, some type of wood boring beetle is suspected. There are several potential beetle pests of pine in our region, including Mountain pine beetle, Western pine beetle, Pine engraver beetles, and, occasionally, the Red turpentine beetle.

The OSU Extension publication “Managing Insects and Diseases of Oregon Conifers” (https://catalog.extension.oregonstate.edu/em8980) is available free online and is a valuable tool for understanding the nuanced clues that can help determine which of the culprits is at work. Management strategies and emergence timings vary per species. Understanding the pest’s life cycles and habits can be the difference between management success or failure.

One thing that all these pine pests have in common is that they typically attack trees that are either stressed, or in decline. In the Klamath Basin, trees that aren’t actively watered are going to encounter drought stress. Watering trees is the best prevention for any of the wood-boring beetles- these insects smell and are attracted to weak and stressed trees. The following information refers specifically locally found species, the Pine engraver beetle.

Early emergence.  
Based on the timing of the calls in May, Pine engravers (scientific name Ips pini) are most likely prompting recent Extension Office calls. Like the other small bark beetles that infest pine, Pine engravers make many, tiny round emergence holes in groups on the trunk of a tree. These small holes are often noticed because of the dust around them or sap oozing from them. Pine engravers start emerging early, and can have several generations per year. Mountain pine beetles start emerging from the trees around July, and the Western starts showing up in June.

Treetop damage.
Pine engraver attacks small trees and large. Small trees are often killed quickly. In large trees, the damage often starts way up in the top of the tree, where details are hard to see. Often, sap high up on the trunk and drying needles high in the tree are the first signs of this pest. Sometimes, the foliage fades very quickly.

Common trees at risk.
The major hosts (food plants) of the Pine engraver beetles are Ponderosa, Lodgepole, and Jeffery pines- the most common pines in our area. Trees in the Klamath Basin are further susceptible if exposed to drought or fire. Trees with winter damage from snow or freeze are also susceptible. Watering these trees deeply and regularly is the most important defense against wood boring beetles.

Time logging and thinning.
For stands of pine that may be at risk to Pine engraver beetles, the best time to log or thin is August-January. The current year’s adults have already emerged, and wood cut during this period dries out such that it’s not suitable to support beetles when they emerge the following spring. For Pine engraver and other wood boring beetles, thinning of stands so there is less competition (more water and resources for the remaining trees) contributes to stronger, unstressed trees less prone to beetle infestation.

Consider removal.
Once trees become infested, removal can quickly become the only option. If caught early in a stand, removal of a few key trees (and the beetles inside them) can contribute to survival of the remaining trees. When cutting down infested trees, care should be taken to prevent moving beetles inside the wood. To kill these beetles in firewood, cover with clear plastic, in the sun, and bury the ends of the plastic so the wood is sealed inside. Leave the wood to cure in this manner.

For complicated situations that require cutting when the timing is not ideal, or for managing large stands of trees of mixed ages, the aforementioned “Managing Insects and Diseases of Oregon Conifers” is most helpful. The identification tools in this guide are easy to use, and it’s packed full of management strategies.

If you need help identifying an insect pest in your own tree, an actual specimen of the insect is always ideal. Also helpful are clear pictures of holes in the trunk, sap or pitch deposits, and affected branches. A picture of the tree canopy showing affected and unaffected parts of the tree is also helpful- for estimating the overall age of the tree and progression of symptoms, but also where in the tree the damage is occurring. All these details contribute to determining which pest is at work.