bugs in firewood

Asked August 10, 2016, 12:07 PM EDT

I cut down 15 or so 30 yr old Doug Firs.... They had died..... long story, but not drought related... some are in good condition for firewood, but some are soft on the outer layer with bugs and larva. I usually stack my firewood between the treated poles of my car port.... the surplus is usually stacked between current trees... I have found that the soft/damp eventually dries, but am concerned about the bugs and larva... Aside from discarding all the infested logs, is there a better solution?

Lincoln County Oregon

3 Responses


Great question! Proper firewood processing, curing, and storage can minimize the problems.

Generally, firewood that has been cut, split, stacked, and left on site for at least one year will ensure the wood has dried or “cured” to the point it is no longer suitable habitat for many wood-boring pests. Debarked firewood is even better—its protective “coating” has been stripped so that it is no longer a suitable host for pests, and you have a cleaner, more efficient heating source. Tarps or other forms of plastic will generate heat in the pile and make an inhospitable environment for pests but monitor the wood for mold or other fungal growth.
For example with Armillaria species or other root, butt, and stem rots some moisture is required for these fungi to survive, but wood stored directly on the ground will likely maintain decay fungi and the community of organisms associated with them, so storing them on concrete (perhaps your carport area) or another surface may help.

This is another great resource for more information related to firewood.
Feel free to contact me directly for more information.

Thanks for the great resources.. I have been a fire wood cutter for many years... spent 30 plus years in Alaska and cut a lot of birch and fir there too. I am aware of the storage of wood, and have been careful not to bring bug infested wood into the house until the last minute...

This is slightly different. These trees had been dead for a couple of years and some are heavily infested...1 - 2 inches of the outer layers. So several cords will probably be this way. I intend to let them sit for a year, or bring them in last minute to burn, but worry how to minimize infesting the good wood.

My second dilemma is how to set up the wood that will be stored for next year... leave it in rounds or split? This will be reserved for the best trees, as I have a lot more than I need and will try to sell the cords.

As far as addressing what is in your downed logs, the beetles and larvae are most likely wood borers (roundheaded and flatheaded borers). These are insects that facilitate the breakdown of dead or dying trees. However, they are not aggressive tree killers and do not emerge and attack healthy trees. No species in Oregon reinvades the same wood from which it emerged. Essentially the beetles normally attack only freshly cut, injured, dying, or recently dead hosts. This would generally happen the first year the trees are down

General Guidelines:

• To prevent degraded log quality, process timber and logs within 1 year after tree death.
• Remove down timber promptly, to reduce damage to wood.

Some of your earlier description indicates decay in the down logs and probably there are a few species of fungi there. As you mentioned, this reduces the quality of your firewood, but should not pose a significant threat to your standing trees. Decay fungi usually do not kill trees, and small amounts of decay will not affect tree growth significantly. Live trees compartmentalize decay; that is, the diameter of the decay column will not exceed the diameter of the tree when it was wounded.

Generally, splitting the wood will allow it to dry more thoroughly, and therefore be less inviting to decay and insect damage helping you to minimize infesting the good wood.

Please feel free to give me a call so I can follow-up further.

Valerie Grant
Forestry & Natural Resources

Serving Clatsop, Tillamook, and Lincoln Counties
Oregon State University
OSU Extension Service, Clatsop County | 2001 Marine Dr Room 210 | Astoria, OR 97103

tel: 503-325-8573
cell: 503-741-5235
fax: 503-325-7910