______ frass contains bun-shaped fecal pellets.

The correct choice pertains to anobiid frass, which is known for containing bun-shaped fecal pellets. Anobiid beetles, particularly those in the woodboring family, produce characteristic frass that resembles small, rounded pellets. These pellets are the byproduct of their wood-consuming diet, and their shape can aid in identification during inspections.

In contrast, termite frass typically appears as a fine powder or sawdust, lacking the distinct shape seen in anobiid debris. Lyctid frass is also powdery and is generated by another type of wood-boring beetle that feeds primarily on hardwood. Carpenter ant frass, on the other hand, is not shaped in pellets but is more coarse and may contain wood shavings mixed with insect parts, reflecting their behavior as they chew through wood to create nesting sites.

Understanding these distinctions is important for pest control professionals, as it helps in identifying the type of pest present and determining appropriate management strategies.