Brown Rot is self-generating because removal of cellulose combined with lignin damage creates a sponginess that is hygroscopic as well as structurally unsound. Here you see the rotted area of this old cedar fence post is at 29% MC on the “A” Scale of my moisture meter….

Interesting and sometimes colorful little algae-fungus combinations that are generally harmless and can be brushed off.

Blue Mold and Ambrosia Beetles

You’ll find Blue Mold (or Blue Stain) without Ambrosia Beetles but you’ll rarely find Ambrosia Beetles without the stain. Various species of molds and sapwood stains feed off the moist sugars in sapwood and discolor it in the process, often permanently.

Here you can see bluish discoloration in the sapwood edge of a Douglas Fir joist. As the joist was recently scrubbed with full-strength bleach, the stain is permanent. You can also see a few bluish pin holes in the sapwood from Ambrosia Beetles. These insects attack stacked logs and downed trees still having intact bark throughout the warm months of the year within as short a period as two weeks.

The adult beetles bore through the bark into the wet sapwood, lay their eggs in the tunnels, and depart. Their secretions plus the sugar in the sapwood attracts Blue Mold development in the tunnels, which their larvae feed on after they hatch and also eventually exit the log to continue the cycle. In some woods the result is considered attractive, and there is a market for “Ambrosia Maple” as one example.

Prevention measures include milling immediately in summer, debarking or ponding logs waiting to be milled, including continuous irrigation of the log stacks with water, which also inhibits other fungi due to oxygen depletion. They cause little real damage and are no further threat once Ambrosia affected wood is seasoned.

Carpenter Ants

Carpenter ants come in small and large sizes and also don’t eat wood, but use it for nesting. They require warmth and nearby food – remove one or both to drive them away.