Which substance can protect wood from powderpost beetle infestation?

The best option to protect wood from powderpost beetle infestation is the use of paint, varnish, or similar coating substances. These products create a barrier on the surface of the wood that can help prevent beetles from accessing the wood underneath. They seal the wood pores and reduce moisture content, making it less attractive to these pests, which thrive in untreated or damp wood.

While natural oils can provide some level of protection, they do not create as effective a barrier as paints or varnishes do. Water is not a protective substance; in fact, it can actually contribute to wood deterioration and attract pests. Glue is also ineffective against powderpost beetles, as it does not offer the necessary protective qualities or barrier needed to thwart insect penetration. Thus, using paint or varnish is the most reliable method to safeguard wood against powderpost beetle infestations.