What life cycle stage of powderpost beetles is characterized by tunneling through wood?

The life cycle stage of powderpost beetles that is characterized by tunneling through wood is indeed the larvae stage. During this phase, after hatching from the egg, the larvae begin to feed on the wood substrate. They create intricate tunnels as they consume the wood fibers, which can lead to significant structural damage in infested materials.

Larval development involves several molts and the larvae may remain in the wood for months or even years, depending on environmental conditions and species. This behavior is critical in the life cycle of powderpost beetles, as it is during this stage that they cause the most damage to wood products.

In contrast, the egg stage does not involve any wood consumption, as the larvae have not yet hatched. The pupa stage follows larval development and involves the transformation into an adult, during which stage the insect is not actively feeding or tunneling. The adult stage, while it may conceal itself in wood, does not cause significant damage compared to the active feeding of the larvae.