Dead Dutch Elm tree trunk and bark

I visited my old friend John W. at lunchtime for a chat at his lovely home on the hillside of the Painswick valley close to Stroud. It was good to hear his news and particularly about the fresh momentum he has with his stereoscopic imaging designs, which I've mentioned several times before in earlier blips. 

We sat in his garden drinking coffee in the warm sunshine and I couldn't resist asking what this wood is which he'd placed on the patio table. He explained that he'd recently cut down a dead tree which happened to be a Dutch Elm. That name carries enormous connotations because 'Dutch Elm disease' is forever associated with the demise of huge numbers of those trees mainly in the 1960s, I think, which profoundly altered the British landscape.

John is very interested in botany and explained about the strange markings on the bark and the section of trunk. An insect, unknown to him, bores through the outer protective bark, which was no longer present here, and then under the inner bark which attached to the trunk. You can see where it arrives because the dark black lines are where it bores into the wood and lays its eggs. 

When the eggs hatch they then bore into the fresh wood and grow by consuming the wood forming the trails which radiate away from the larger darker lines. As they grow the width of their boring becomes larger, which you can see here by the growing width of the trails as they progress away from their original 'birth' position.

John says that the insect does not cause the disease, but apparently carries a fungus, which he thinks probably causes damage to the cells. These carry the sugars and moisture up and down the plant and if they were to constrict, their capacity to feed the tree would diminish and then the plant could not survive.

I do think the resulting trails are rather interesting, and beautiful, despite being the harbingers of doom. Life can be like that.