What is the appearance of glassworm damage in white ash?

• A. A zigzag pattern of light-colored wood caused by the cambium miner, which can turn nearly black.
• B. A straight, uniform grain with no discoloration.
• C. A circular ring pattern similar to decay.
• D. Random specks that fade over time.

Answer: (A)

The key idea is that glassworm damage comes from larvae feeding in the cambial zone between bark and wood, which creates a meandering, zigzag gallery. This feeding disrupts wood formation and leaves a path of lighter-colored wood along the cambial tract. Over time, staining from the damaged tissue or fungal activity can darken these areas, sometimes becoming nearly black. So the telltale sign is a zigzag pattern of light wood that may darken with time, not a uniform grain, circular rings, or random specks.