Since I started looking, I have identified at least 4 different kinds of beetles munching on my wood. I guess they all get lumped together as powder post beetles, but given that one is called the "true powder post beetle," the other probably aren't true powder post beetles.
One particularly voracious beetle, the ambrosia beetle, especially likes yellow poplar, maple, walnut, and chestnut oak. This beetle works on green wood, prefers sapwood, and the ADULTS do the damage. I have left boards next to my sawmill overnight, only to return the next day and find that it looks as if they've been peppered with a shot gun. These beetles work FAST. Within 12 hours, they can bore about 1/8th inch into the wood. If you pour diesel on them, they back out of their holes and die within a minute. If you pour undiluted Boracare on them, they plow around, pull theirselves out of the puddle, and start boring again!
I took a mason jar full of these live critters to a KY state forestry worker, and he took them to UK and they ID'ed them for me. It looks like they have two segments to their bodies, because their head is tucked under their midsection. They are usually black and about the size of a poppy seed. At certain times of the year, the air is thick with them flying and you might mistakes them for gnats. They bore and lay their eggs in the sappy wood, where conditions are just right to grow "ambrosia" (beetle beer). When the youngsters hatch, they drink the fungal fermentation. This is what I've been told, and observations support this. Consequently, I've been told they do not work on dry wood, and would likely not re-infest my wood once it is inside my house. I hope this is true, because they can take a beautiful (green) board or timber and perforate it in less than 24 hours. The saw dust that comes out of their holes usually looks like little soda straws. I have even seen them working on _live_ yellow poplar trees. After I started looking, I even found one in an ear of corn.
As mentioned by other posters, most of the damage caused by the other wood boring beetles is said to be attributable to the youngsters that hatch. (although I haven't observed them in action like I have the ambrosia beetles - I've only seen the adults, and then observed the damage.) I spent over $1000 on Boracare to treat the timbers that are going into my house. I'm not sure if it was a waste of money or not. In other words, I have observed substantial wood-borer damage on timbers within 6 months of drenching them with boracare. (boracare mixed 1:1 with water, per manufacturer's directions) To be fair to the manufacturer (and to try and rationalize the money I spent on the boracare!), perhaps the boracare will kick-in and protect my wood against subsequent generations of beetles, or maybe beetles would have damaged my wood even more if I had not treated it with boracare. In any case, Boracare is not a panacea... read their disclaimer before you buy it. (does not guarantee protection!)
There is at least one kind of wood boring beetle that does work on heart wood. I have seen it - it seems to love my white oak timbers. I will post pictures of their handy-work on my web site before the end of today.
Kiln drying at high enough temperatures should kill the adults and their eggs. I did that for my tongue-and-groove ceilings, but that wasn't an option for my timbers. I guess the best strategy is to oversize your timbers and leave enough wood to share with the creatures?
new timber frame house in progress - with pictures of wood borer damage.
