Conservation of Ancient Timbers from the Sea 281
sustain growth and decay ability. Studies with terrestrial white rot fungi have
shown that lignin degradation is a highly oxidative process and it can be
assumed that this is true of basidiomycete decay of wood in the sea.
2.9 Insect Borers
One important biodeteriogen that can cause damage to recovered archaeological
timbers is the insect Nacerdes melanura (Oedemeridae) – the wharf-borer.
This insect has a world-wide distribution and is found in freshwater inland
sites and damp timbers in terrestrial sites as well as marine pilings, wharves,
jetties, etc.The larvae that are 12–30 mm in length, burrow into both hardwood
and softwood timber, but have a preference for softwoods (Figure 11). Although
the wharf-borer is generally regarded as a pest of damp decayed timber, lar-
vae do infest wood at or just above the high-water mark and have been observed
burrowing into sound wood in close proximity to decayed wood. During the
conservation programme for the Tudor ship Mary Rose, larvae were found bur-
rowing in stored waterlogged archaeological timbers. Larvae were found in
oak, poplar and pine timbers, but those affected made up only 2% of the total
examined. The moisture contents of the timbers ranged between 131 and 670%
and larval burrows were found to a depth of ca.1 cm, where soft rot and bac-
terial decay were present.
Another potential pest of timbers in maritime situations is the wood-boring
weevil Pselactus spadixthat can excavate galleries in the inter-tidal and splash
zones of wharf timbers. The larvae are believed to be the primary tunnellers,
Figure 11Wharf-borer adult beetle emerging from a hole in the wood surface