What's the difference between sapwood and hardwood?
Sapwood is the newest wood in a tree:
1. much less durable than heartwood because there are no extractives contained in the wood.
2. very attractive to fungi (rot-producing organisms) and insect attack because the sap is very high in starch, and remains in the sapwood even after the wood has been milled, dried and processed. Some insects such as lyctus generally lay their eggs in the hollow cells.
3. lighter in color.
Heartwood is older, more durable than sapwood, and often harder, although it is not necessarily stronger. In heartwood where the cells are already full of extractives, the eggs cannot be laid and the wood-consuming larvae cannot be produced. Therefore most heartwood is not susceptible to lyctus attack.
