I have 5,000 4/4 board feet of hardwood that has been air-dried in a drying shed (black mesh sides) for a few years. Moisture is approximately 12 percent. The lumber was attacked by Powderpost beetles early on but I haven't noticed any new infestation since then. Are the Powderpost Beatles no longer an issue? Can I move lumber now and flat stack in an unheated warehouse for storage? MC is maintained in the Warehouse with adequate temps and dehumidifiers. I wouldn't want to infect other hardwood species inside the warehouse?
It sounds like they had ambrosia beetles move through early on, they left when the moisture content dropped. Powderpost beetles don't mind dry wood so if you have any they are still there and if so, storing the wood with other dry wood is a good way to spread them.
I agree that you do not have the lyctid powderpost beetle.
The ambrosia beetles can survive in stickers, 4x4s, pallets, debris in the air yard, and so, you need to tidy up the air yard. Poisons do not work well, as the insect has to be out and about when the poison is used. Almost all their life is spent inside the wood.
What confused me is the powder sawdust piles had only occurred on specific Maple & Hickory stacks and not close by stacks of softwoods, or within the other drying hardwood sheds further away.
Cleaning up the yard would be good idea as well as making sure stickers, 4x4's, etc...are bug free. Is the only sure solution on this 5,000 bd ft of lumber to heat it properly in a Kiln to kill any potential beetles?
That's the only sure solution I know of to kill what might be there. Remember there is no residual action with heat, it doesn't mean the wood cannot be bug food later.
If that lumber will be used for an interior project in the future it will need to go through a kiln anyway to drop the MC down to around 7%. Using it at 12% will result in a fair bit of movement, shrinkage, etc. if it lands in a climate controlled home.