Which type of frass is described as tightly packed and fine powder?

The type of frass that is described as tightly packed and fine powder is associated with the Old House Borer. This frass, which is the term used for the excrement of wood-boring insects, tends to be very fine and often resembles sawdust or powder, indicating that the insect has been actively consuming wood.

The Old House Borer, a wood-boring beetle, creates these powdery droppings as it feeds on structural wood and is known for causing damage in older homes and buildings. The fine, powdery nature of their frass results from the beetle's feeding habits, which involve boring into wood and expelling finely-ground wood particles.

In contrast, the other types of frass mentioned have distinct characteristics. Ambrosia frass is generally more varied in texture due to its association with ambrosia beetles and contains fungal spores alongside the wood particles. Bostrichid frass can be more granular and is indicative of woodboring beetles that make larger holes in wood. Lyctid frass also has a different texture and can be coarser due to the larger size of the larvae. Understanding these differences helps in identifying the specific type of infestation present.