The 'Wood Wreckers' (Part 1)

By Paul James

 

I guess it's because I live in the country surrounded by woodlands, hedges as well as agricultural buildings that I never fail to stumble across new evidence of decaying timber on an annual basis. At any time of the year during inclement weather, which is essentially damp and warm here in the UK, there is increased timber decaying activity, more especially now that our autumns and winters seem milder. As pond water is a rich source of countless life forms for the amateur to research, so too is decaying timber. Most of the inhabitants that frequent and destroy wood, albeit indirectly, favour damp conditions : not too wet nor dry. In such a situation wood will be the host to many varieties of bacteria, algae, fungi, lichens and many insects. In most cases all these life forms will be simultaneously present, each inadvertently aiding the others through their own biochemical processes and physical alterations of the timber, which is eventually destroyed in the process. Wood is of course one of their principle sources of food, though the rate at which timber can be consumed varies considerably between the timber species. The fastest decay usually occurs outside in shady places and at ground level where the conditions are ideal, and for eons the soil micro community has evolved into extremely efficient wood destroyers. Even in sheltered conditions of a house wood can still play host to attack when its moisture content rises.

I've therefore posted some imagery which might be of interest to readers who might like to investigate this interesting line of study for themselves. To this end I've just included simple images with very brief descriptions, hoping to whet the reader's appetite on this very broad subject. There is enough to see with the eyeglass, stereo and compound microscope to keep the amateur going for years.

Halved section of Wych Elm Handrail In the open For 15 Years (x0.75)

 

Severe upper surface deterioration from fungus, algae, worm and lichens.

I've cut the rail down middle to show that the inner wood which is slightly stained from fungal attack

and a couple of filled worm holes. Otherwise the timber's reasonably sound inside.

Close Up of Exposed Handrail (x5)
Shows fracturing of wood into cubic surface pattern from alternate wet and dry weather which

provides damp crevices attracting both fungus and algae.

Old Exit Hole (x12)
Close-up of worm/beetle exit hole showing signs of weathering indicating the hole

is a few years old. Note the early establishment of blue green lichen.

Pair Of Worm/Beetle Exit Holes (x 12)

Two exit holes chewed out several years apart. New holes are amazingly sharp edged. The

one left is probably last years'. Note the surface cracks and in particular the colonisation of

green algae communities along their edges, where moisture will tend to remain in dry spells.

Old Floorboard's Inner Maze of worm galleries (x2)

This is a narrow sawn section of an old 75 year old floorboard, which after

planing revealed the true extent of the wood borer's activities. Note the range of hole diameters and the longitudinal

galleries.

Side view of Floorboard' edge (x3)
Note the activity of the borers is mostly confined to the starch richer layers of spring wood between the

alternating darker bands of summer wood. Transition from one layer to another accounts for the forays

through the denser summer wood. Image colour saturation was deliberately increased to show summer wood.

The heartwood which lies beneath the sapwood is rarely affected in this particular wood species.

Close-up of cross section of internal gallery (x25)
Shows the 'bite marks' from the larva's pincers or mandibles.
Wood Boring Larva (x15)

Typical 'grub' probably Anobium Punctatum

Pincer like mouth show tips apart (X35). Note the pellets which are the waste products after digestion.

Unfortunately all the images above have had to be severely compressed to enable uploading owing to my poor dial-up connection.

Their quality is unfortunately not up to the standard that I'd ideally wish them to be.


All comments welcome by the author Paul James

 

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