What is often found in large quantities at exit holes and cracks where lyctids are present?

The correct answer is that frass is often found in large quantities at exit holes and cracks where lyctids are present. Frass is the term used for the sawdust-like material produced by wood-boring insects, including lyctids, which are a type of wood-destroying beetle. This material consists of the wood particles that have been processed by the insect as it tunnels through the wood to feed and create galleries.

When lyctids infest wood, they create exit holes as they emerge from the wood after fully developing. The frass accumulates around these exit holes and in the crevices where they perch because it is expelled waste material resulting from the boring activity, which can help in identifying active infestations. Observing frass is a common indicator of wood-boring insect activity and assists inspectors in diagnosing potential damage to wood structures.

The presence of frass is important for homeowners and inspectors alike as it signals the activity of wood-destroying organisms and may necessitate further investigation or treatment to prevent structural damage.