Five-spined Ips Still Here and Causing Trouble

Gwen Berry, with excerpts from

Remember a few years ago when a new bark beetle, the Five-spined Ips, was discovered killing pine trees in our area? It had spread north from California and finally reached the Columbia Gorge. Most of us are aware of the increasing damage being done to our forests by invasive insects. The many dead pine trees throughout our Gorge area, killed by the invasive Five-spined Ips, testify to the vulnerability of our forested areas. 

The following paragraph is from a Washington DNR publication, “Forest Health Highlights in Washington – 2019”:

“Pine mortality attributed to Ips pine engravers was observed on approximately 3,900 acres in 2019, more than three times the 1,100 acres observed in 2018. Similar to WPB (Western Pine Beetle), this is the highest level recorded since 2006. Ponderosa pine was the most common species affected. The highest concentration of 2019 mortality was in Klickitat County. In the southern part of the county, near the Columbia River Gorge, California Five-spined Ips (Ips paraconfusus) is the most likely species responsible for mortality. In north Klickitat County and elsewhere in Washington, Ips pini is more common.”

The first signs of attack are multiple small accumulations of fine, light-colored powder (frass) upon the surface and in crevices in the bark of the tree, where it collects after being excavated from burrows drilled into the phloem by attacking adults. The burrows themselves are often not visible without removing bark flakes. The Five-spined Ips prefers top branches, and branches or boles up to 3”, where the bark is thinner and easier to get through.  

Infested trees develop a ‘red flag’ appearance in the crown, as needles in branches above attack sites begin to turn red.  Later on, the entire crown turns red and then brown. The bark becomes riddled with 1.5-mm emergence holes made by emerging offspring and can be pulled off readily due to beetles and other insects mining the phloem layer under the bark.

As the tree under attack becomes even more stressed, other insects are attracted and attack the lower parts of the tree. Once under attack, a tree very rarely survives, although it is not always easy to establish whether Ips actually killed the tree, rather than other co-attacking species, or whether the tree was dying from other causes that predisposed it to bark beetle attack. 

Winter is the very best time to take action on forest problems. Around here, that means from October through the end of January. If you wait until insect pests become active in the spring, all your trimming and clearing will become a smorgasbord for the bugs and encourage further infestation. If you wait for the fair days of summer and fall, fire danger makes forest work risky.

If you can’t do the work until spring, you can minimize the chances of infestation by making sure all your cuttings dry out as quickly as possible. Leave your small slash in a loose, open pile in a sunny location, or cover it tightly with clear plastic so it gets too hot for insects underneath the plastic. You could also run all your trimmings through a chipper and turn it into small pieces that will dry quickly. It would be ideal to remove the bark from anything too big for the chipper.

Now is the time to begin trimming and clearing pine branches and saplings on your property, while fall temperatures are moderate and the snow is still in the future. You can help reduce Ips infestations and the loss of beautiful Ponderosa pines throughout Klickitat County.

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