An EHS Pest client referred a Needham homeowner to us when the started seeing small holes and fine powder on their beautiful new, hardwood floors. We asked for a photograph and it was promptly sent to us. You can see the adult beetle, exit hole and fine, talc like frass (powdered wood).
The insects are Powder Post Beetles. They are emerging from these floorboards after there second stage of metamorphosis, the pupal stage as as adult beetle.
This flooring was not properly kiln dried or treated at the sawmill facility. These native wood destroying insects later eggs in these planks and the beetle larva (grubs) fed and developed inside.
They remained until a year after installation until the right time came to emerge. That's when the homeowner was alarmed and contacted EHS.
I told the worried homeowner that as long as the structure is weatherproof and has a heating system (not an open barn) and no major moisture problems there is a zero percent chance of re infestation.
These insects will however continue to emerge from these planks. You will see the exit hole and frass (fine powdered wood) until the cycle is complete. Most homeowners that don't care for this antique look simply refinish the wood when the mass emergence is complete.
Furniture companies use this wormhole technique to age furniture and charge a premium for it.