Lost Some Trees to Bark Beetles (Shallow Thoughts)

Lost Some Trees to Bark Beetles

This year's drought was fierce. We only had two substantial rainfalls all summer. And here in piñon-juniper country, that means the piñon trees were under heavy attack by piñon Ips bark beetles, Ips confusus.

Piñon bark beetles are apparently around all the time, but normally, the trees can fight them off by producing extra sap. But when it gets dry, drought-stressed trees can't make enough sap, the beetles proliferate, and trees start dying. Bark beetles are apparently the biggest known killer of mature piñon trees.

We're aware of this, and we water the piñons we can reach, and cross our fingers for the ones that are farther from the house. But this year we lost four trees -- all of them close enough to the house that we'd been watering them every three or four weeks.

Some of the four trees were a little sickly to begin with, but one was a large, healthy tree out in front ot the house. We tried hard to convince ourselves that it wasn't really dead (okay, the top's obviously brown, but look, there are still a few green needles down low, maybe it'll recover!) But we finally had to admit that it was a goner.

When a tree dies from a bark beetle infestation, it's important to get it away from other trees quickly. The beetles lay their eggs under the bark, and when the new generation of beetles hatch, they move to nearby trees.

During summer, we'd been following the usual advice to cut the tree into sections and seal the sections in plastic in full sun (either black plastic for solar heating, or clear plastic for greenhouse effect). (This turns out to be trickier than it sounds and tends to require a lot of duct tape, since neither garbage bags nor clear plastic sheeting are particularly strong, and trees are full of sharp protruding bits.)

During winter, though, it's not clear that the plastic trick would get the wood hot enough ... and besides, we have a fireplace, why not get some use out of the wood? So we spent the last couple days madly trying to bring down the 35-foot-or-so tree and cut and split the wood into fireplace-friendly sized pieces, trying to beat the snowstorm that was forecast to start tonight.

All the sources say the that I. confusus's life cycle ends in October, but this has been an unusually warm fall. When we split some of the larger pieces, the bark fell off and revealed the live beetles crawling around between the bark and the wood. Ick. Those bark pieces went into a garbage bag until they can be burned.

At least now we know what they look like, and we know for sure that that's what killed the tree. I just hope we can figure out how to protect the rest of our little woodland as drought becomes an increasing problem in the southwest.

It'll be interesting to see how long it takes to burn the (green) wood, bark and branches from a mature 35-foot piñon tree.

A few Pinon Ips references: Colorado State, Arizona State Extension, USDA.

Tags: nature, pinon, bark beetles
[ 18:38 Dec 23, 2021    More nature | permalink to this entry | ]