Made a new friend/unwanted guest

[Kelby Van Patten]

I bought some spalted maple from a local hardwood dealer about four months ago. I milled it up last night, and look what I found crawling around inside. Which raises a couple of questions: (1) What is it? Rummaging on google, it looks to me like a powderpost beetle larva. (2) Should I get rid of the board? I would assume there may be more inside. (3) This board has been sitting in my shop for several months, alongside some valuable mahogany. What, if anything, do I need to do to make sure my mahogany is safe/uninfested? (4) Any chance this came from something else in my shop? I thought these beetles had an 18-24 month gestation cycle, and the board has only been in my shop for a few months. (5) The lumber yard I bought this from is a pretty reputable place, but shouldn't the kiln-drying process have killed these things?

[Paul Murphy]

Could your wood have been dried in a dehumidification kiln? If so then I believe the process lacks the heat component which would have probably killed that insect.

[Kelby Van Patten]

Paul, good question. I do not know how it was dried.

[Ole Anderson]

You could ask your supplier. I am sure they would be interested in what you found.

By the way, if everyone listed their location in their profile, we would know whether we should start worrying about our wood sources.

[Richard Coers]

I don't think any stage of the powder post beetle gets over 1/16" diameter. Maybe you are a great photograher, but that looks bigger than that.

[Izzy Camire]

Probably not it but it looks a lot like the larvae of a pine beetle.

I would take the board back at the very least. I am sure they want to know and by returning it you get it out of your shop and get a new board.

[johnny means]

Couple of years ago I got a call back from a job in Miami, I'm located in Delaware, for a piece that had powder post issues. Had to go to Miami, disassemble, deliver to fumigator, wait 2 days, pickup, and redeliver/assemble the piece. Several thousand dollars of fixing that I swallowed ( it was pretty obvious that the problem was built in). All this from using some "good deal" lumber for a couple of small interior cleats. Point being, don't take any chances if your the slightest bit suspicious. On the bright side, it did turn out to be a nice Christmas vacation for the family.

[Scott T Smith]

Could your wood have been dried in a dehumidification kiln? If so then I believe the process lacks the heat component which would have probably killed that insect.


Paul - my experiences with dehumidification kilns runs counter to your statement. ALL commercial dehumidification kilns are completely capable of sterilizing the lumber that they dry, and all reputable kiln operators will run a sterilization cycle at the end of the drying process. There are several different sterilization schedules published by the USDA; the most common one is to heat the core of the board to 133F or greater for a period of at least 4 hours. All of the kiln drying courses that I have attended have also stressed the importance of a sterilization cycle at the end of the kiln run.

Hobby dehumidification kilns that use small production units or home dehumidifiers are a different story, but these are usually not used in commercial production.

Lumber dried in dehumidification kilns offers woodworkers the best of all worlds, as it is typically dried at lower temps (which more closely replicates the workability characteristics of air dried lumber), yet it has the benefits of being sterilized at the end of the kiln cycle.

Kelby, you are correct regarding the gestation cycle for PPB, but unless you have a tremendous magnification on your camera that is probably not a PPB (they are only around 1/32" in diameter - or around .030).

PPB's will infect already dried lumber if they are exposed to it. If your maple was properly kiln dried around 2 years ago and was subsequently exposed to PPB, then this could explain the problem.

[Paul Murphy]

Hi Scott, I have the highest respect for your operation, and there is no doubt in my mind that you go well above and beyond best industry practice. I have air dried lumber from my own property for over 20 years, and have done without a kiln. I have also bought a fair amount of lumber in recent years from a small sawmill that uses a dehumidification kiln, and have been satisfied with the quality of the lumber. This sawmill is a small operation consisting of the owner and one employee, so I’m not sure if they are “commercial” in scale. I like them because they saw nice logs into nice lumber, and I can buy all the wood from a single tree for my furniture project. As far as my use, the kiln just reduces the time lumber acclimates in my shop before it can be used.

Anyway, I’m often absolutely incorrect, and my wife never lets me forget it :D!

Just to defend my information, it is from EBAC a manufacturer of dehumidification kilns:

http://www.ebacusa.com/downloads/brochures/LD800.pdf (http://www.ebacusa.com/downloads/brochures/LD800.pdf)
“Extra equipment such as venting
units and supplementary heaters are normally
not required.”

“Designed to operate up to 113°F (45°C). The LD800
can dry wood from green or air dried, to 6% moisture
content if required.”

It looks like this EBAC kiln is shy by 20°F of the sterilization cycle you mention.

[Scott T Smith]

Hi Scott, I have the highest respect for your operation, and there is no doubt in my mind that you go well above and beyond best industry practice. I have air dried lumber from my own property for over 20 years, and have done without a kiln. I have also bought a fair amount of lumber in recent years from a small sawmill that uses a dehumidification kiln, and have been satisfied with the quality of the lumber. This sawmill is a small operation consisting of the owner and one employee, so I’m not sure if they are “commercial” in scale. I like them because they saw nice logs into nice lumber, and I can buy all the wood from a single tree for my furniture project. As far as my use, the kiln just reduces the time lumber acclimates in my shop before it can be used.

Anyway, I’m often absolutely incorrect, and my wife never lets me forget it :D!

Just to defend my information, it is from EBAC a manufacturer of dehumidification kilns:

http://www.ebacusa.com/downloads/brochures/LD800.pdf (http://www.ebacusa.com/downloads/brochures/LD800.pdf)
“Extra equipment such as venting
units and supplementary heaters are normally
not required.”

“Designed to operate up to 113°F (45°C). The LD800
can dry wood from green or air dried, to 6% moisture
content if required.”

It looks like this EBAC kiln is shy by 20°F of the sterilization cycle you mention.


Paul, thank you for the kind words and very well written response! I think that I'm going to modify my original response just a bit...

Yup, you're right about the EBAC LD 800 unit; but this unit is designed for a hobbyist (120VAC operation). When you move up to their MF2 system (5K bd ft - which is around the average minimum size for a small commercial operation), it operates up to 140F, which is adequate for sterilization.

Nyle's smallest DH system - the L200, is equipped to sterilize as well.

It is beyond my comprehension that a kiln operator would intentionally not sterilize the load at the end of the cycle; as that is one of the greatest benefits of kiln dried lumber. I'm sure that there are operators that might skip this step, but I don't understand why someone would want to take that risk...

Air drying certainly works well in many parts of the country, and especially with certain species such as black walnut.