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Pine Engraver Beetles Profit from Tornado-Toppled Trees Around Custer

A tornado knocked down trees near Custer in May. Now those downed trees are feeding pine engraver beetles:

“The downed trees are quickly becoming infested with the engraver beetles” says Greg Josten, South Dakota State Forester. “Once the beetle raises a new generation inside this fallen material, the new adult beetles will leave this wood and may attack standing live trees.”

Engraver beetles are native bark beetles producing two to three generations per year. If there is not fresh green slash available for the beetles, the summer generation of engraver beetle often moves from downed trees to live trees, especially during droughts.

If possible, landowners should cut the limbs and branches of these downed trees into short lengths, about three feet long, and scatter them so the wood dries out before the adult beetles emerge. Logs should be salvaged, taken to a local sawmill, and debarked as soon as possible. Removal of the bark will destroy the beetles. Slabbing, the process of squaring a log which leaves the bark attached to the wood, does not kill the beetles.

Another option is to cut infested trunks into short lengths, two or three feet long, and cover them with 6-mil clear plastic. The plastic must be sealed to the ground at all edges. This solar treatment will heat up the wood and reduce the number of beetles that survive in the logs and emerge.

Right now, many of the ponderosa pine trees uprooted by the tornado are covered with the fine reddish-brown boring dust created as the beetles burrowed into the stems and branches. Once inside, the adult beetles lay eggs and once those eggs hatch the larvae feed and grow inside the wood. They will emerge as adults sometime in July [SD Department of Agriculture and Natural Resources, press release, 2021.07.07].

Pine engraver beetles are not the same critter as the mountain pine beetles that plagued the Black Hills a decade ago:

While the pine engraver beetle is closely related to the mountain pine beetle, it is an entirely different insect. The pine engraver beetle is common to the Black Hills and it also attacks pines, but its life cycle and the management recommendations are different.

The pine engraver beetle often first attacks the tops of the trees while mountain pine beetle attacks are along the lower 3/4 of the tree. Mountain pine beetle attacks generally result in the formation of pitch tubes while pitch tubes are rare with pine engraver beetle attacks. The galleries created beneath the bark are different. Mountain pine beetles form one large gallery with many smaller ones constructed perpendicular from the main one. Pine engraver beetles have several large galleries radiating out from a central location [SD Department of Agriculture, “Mountain Pine Beetle: Identification and Biology,” retrieved 2021.07.08].

Custer neighbors, keeping running those chain saws….


  1. Mark Anderson 2021-07-08

    Well Cory, maybe those Pine Engraver Beetles will bitcoin profit by moving to Wyoming.

  2. grudznick 2021-07-08

    I would have guessed that as a libbie, Mr. H, your take on these bugs would have been “Don’t burn more chainsaw gas and pollute the air with noise and exhaust, let nature take its course.” But I’m with you, fire up the biggest chainsaws you have and chop those toppled trees into sawdust.

  3. Arlo Blundt 2021-07-09

    well..grudz aside, pine beetles are a big deal, aesthetically and economically. People banded together in Custer County and did a good job of battling the pine bark beetle. The beetle must go…a good project for the Governor’s office to sponsor…after all, we have plenty of money.

  4. Cory Allen Heidelberger Post author | 2021-07-09

    I’d bring my electric chainsaw, but I don’t think my extension cords will reach out into the forest.

    When disaster strikes I’m willing to suspend carbon-emission regs and seek offsets later.

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