Which life stage of wood-boring beetles causes the most damage to wood?

The larvae, or grub stage, of wood-boring beetles is responsible for the most damage to wood. This is because the larvae typically feed on the wood as they develop, creating tunnels and galleries that weaken the structural integrity of the wood. Their feeding activity not only destroys the wood itself but can lead to significant structural damage in buildings and other wooden structures over time.

In contrast, the adult stage primarily focuses on reproduction and does not cause significant damage to wood. The pupal stage is a transitional phase in the lifecycle of the beetle, during which the insect is not actively feeding or causing damage. The egg stage marks the beginning of the lifecycle, and while the eggs are essential for the continuation of the species, they do not directly interact with wood or cause damage until they hatch into larvae. Thus, the larval stage is the most destructive phase in the life cycle of wood-boring beetles.