Pin-hole borer damage to timber, caused by beetles of the families Scolytidae and Platypodidae, is associated chiefly with recently felled logs and occasionally with standing trees which are in an unhealthy condition. Information collected within recent years by the Forest Products Research Laboratory, Department of Scientific and Industrial Research, suggests that attack in standing trees may, however, be of more frequent occurrence than has been commonly supposed. In this connection, an interesting case of damage to English ash by the Platypodid beetle, Platypus cylindrus, F., is worthy of record.