The answer to 'why is my carpenter ant scratching sounds' is that the scratching sounds are likely caused by carpenter ants nesting inside your home. Carpenter ants are known to make audible scratching or rustling noises as they tunnel through wood to build their nests. This is a common sign of a carpenter ant infestation.
Carpenter ants don't actually eat the wood, but they do hollow it out to create their nests. This can cause structural damage over time if left untreated. Other signs of a carpenter ant problem include seeing the ants themselves, piles of wood shavings, and damage to wooden structures in your home.