of sufficient size to accommodate the insect’s ovipositor, damage by this
beetle is restricted to hardwoods with large vessel elements (Bravery et al.
1987), as well as bamboo and rattan, which have large vascular elements.
Moisture content is also an important factor for wood-boring
insects. The Lyctusand Anobiumbeetles require relatively low wood-
moisture levels of 8–20% for continued activity (Creffield 1991). However,
damage can also occur and is often most severe in woods exposed to damp
conditions. Other wood-boring insects, such as ambrosia and bostrychid
beetles (Fig. 6), require a wood moisture of greater than 30%. Many
wood-boring insects attack only wood that has been previously altered by
decay fungi (Table 2).Termite damage
Termite damage has been found to affect some panel paintings that were
in direct contact with the walls of infested buildings in tropical regions
(Boustead 1968), but otherwise this type of damage is not frequently
encountered by museum conservators. Termites eat the interior portions of
the wood, leaving a thin shell of exposed wood. Damage can be extensive
and is easily recognized by the broad feeding galleries in the wood. Damp-
wood termites and some subterranean termites have a preference for moist
wood and are often associated with wood in an early stage of decay by
wood-rotting fungi. Galleries follow earlywood regions, leaving thin zones
of latewood behind. Dry-wood termites also require moist wood but do
not need an external source of water. A diagnostic feature of drywood-
termite attack is fecal pellets that accumulate in excavated galleries of the
wood. Galleries also lack orientation with the wood grain. A great deal of64 Blanchette
Figure 8a–c
Insect tunnels and frass of the common furni-
ture beetle,Anobium:(a) Cut wood from a
stretcher (seventeenth century, Italy) with
boreholes caused by the larval stage of
Anobium.The size of the tunnel reflects the
size ofthe growing larva as it feeds on the
wood. Insect frass (arrows) is usually held
within the tunnels (in this sample, however, it
has fallen out during cutting); radially sawed
wood, bar = 1 cm; (b) and (c) Anobiumfrass
consists ofpellets and fragments ofwood.
These small frass pellets are characteristic of
Anobiumattack. Scanning electron micro-
graphs; bar = 250 μm.
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