A Powder Post Beetle is a small Wood Boring Insect which will reduce wood to a fine powder. Powder Post Beetle Damage is done by the larval stage as they make narrow tunnels in wood as they feed.
Beetles a very small about 1/8.” They can be reddish brown to black. You are more likely to see damage than the beetles because the adults are short-lived and are active mainly at night. The larvae is a small grub like worm,
c-shaped and cream in color.
Powder Post Beetles themselves are not dangerous but the damage they cause could be if extensive enough to cause Structural Damage. Most Powder Post Beetle Damage is found in older hardwoods. Even with half the beam gone it is probably still stronger than the soft pine used today. But I am not a Structural Engineer.
Two signs of Beetles would be small Pin Holes on the surface of wood and a powder like pile below the wood. This substance is call Frass and many pests create frass so let a Professional Exterminator determine what you have.
Powder Post Beetles are introduced into buildings in lumber, old furniture, paneling or flooring. Wood may have been improperly stored or dried. Many houses have lumber that was milled before wood was treated. Powder Post Beetles can fly in from surrounding areas.
Powder Post Beetles damage wood slowly so you have time to decide on the proper plan for you. Powder Post Beetles will only lay their eggs on bare, unfinished wood. Wood which is painted or sealed will provided less surface to infest and lay eggs. Controlling humidity levels is important. You can go so far as to replace infested and damaged wood. Two treatment options would be one Fumigation, this is very time consuming and expensive. And two surface treatment, this is the most common approach and affordable. Rob can explain all that in detail.