What substance is commonly found falling out at exit holes and cracks that house lyctids?

The substance that is commonly found falling out at exit holes and cracks where lyctid beetles are present is known as frass. Frass is the term used to describe the droppings or excrement of wood-destroying insects, including lyctids, which are a type of wood-boring beetle. When these insects infest wood, they consume it and subsequently produce frass as a byproduct of their digestion.

This frass typically appears as fine powder or small pellets and can accumulate around the exit holes made by the adult beetles as they emerge from the wood. Observing frass can be a key indicator of an active infestation, as it signifies that the lyctids are currently residing within the wood structure.

In this context, other substances such as wood shavings, insect eggs, and soil are not typically associated with the activity of lyctids. Wood shavings may arise during the wood-boring process but are not the primary indicator of an infestation. Insect eggs would indicate the potential for future infestations rather than confirm current activity, while soil is unrelated to the behavior or biological processes of lyctids, as these beetles do not interact with soil in their lifecycle. Thus, the presence of fr