This is some termite damaged timber that has been treated with Arsenic trioxide dust. You can see the remnants of the arsenic in the galleries in the timber, its bright red! Arsenic trioxide dust was introduced many years ago as a means of treating live termites in their workings in an attempt to eradicate the colony. Whilst it has been an effective means, arsenic trioxide is extremely toxic and there are much better methods nowadays that don't introduce toxic chemicals into your property. Termidor dust and baiting are just some methods that can be used. Unfortunately, arsenic trioxide is still readily available and still being used by pest controllers in Australia.