Platypus cylindrus, commonly known as the oak pinhole borer, is a species of ambrosia beetle in the weevil family Scolytinae.

It used to be considered rare in Britain, but after the Great Storm of 1987, when many trees were blown down in southern England, it took advantage of the abundant supply of timber and became much more common.

The female extends the tunnel further, working radially, and the male pushes the wood fragments out, leaving a pile of frass.

[1] The walls of the gallery soon become covered with a layer of ambrosia fungi, spores having been introduced on the body surface of the beetles.

The larval stage lasts for about two years, then the larvae create small chambers in which they pupate, later emerging into the open air as adults without doing any more tunnelling.

Insecticides have no effect on adults and larvae inside their tunnels, but kiln drying of the timber can kill them when the fungus is unable to survive the desiccation.