First 2 pic's show a dead tree. Third pic shows bugs which live under the dead bark, but the killer is what ever made the holes.
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We have a lot of trees in our very local woodland with holes just like these Ken,
Maybe this is the culprit http://www.defra.gov.uk/planth/pestnote/citruspics.htm
What sort of tree is it Ken. Although there are oak leaves shown in the first picture, they look as though they are on a neighbouring oak. The tree in question looks fairly old. Could it be that the younger oak is taking up all the nutrients and water? Can you get a close up picture of the beetles on the tree please?
Under the dead bark are hundreds of woodlice. The beetle that made the holes I've not found yet.
Some big holes. Some small.
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the holes look like woodpecker damage, they'll be after the grubs. ;)
I'm with Tony (not in the biblical way!) - the holes are from a pecker of wood... unless it was you who made the holes to pour in the glyphosate?!?!
The small neat holes are beetles, the bigger ones are woodpecker. But something else probably killed the tree; beetles like rotting wood in the main.