On system.log and gzipped system.log files:
$ (cat *.log; zcat *.gz)|grep USBMSC|sort|tail -5
2016-12-22 20:53:50.025584+0900 0xc214 Default 0x0 0 kernel: (IOUSBFamily) USBMSC Identifier (non-unique): 4C530006070617103092 0x781 0x5576 0x127, 2
2016-12-22 21:16:01.842416+0900 0xc230 Default 0x0 0 kernel: (IOUSBFamily) USBMSC Identifier (non-unique): FF05080500133 0xf5f 0x1325 0x100, 2
2016-12-22 21:34:42.581755+0900 0xdecb Default 0x0 0 kernel: (IOUSBFamily) USBMSC Identifier (non-unique): FF05080500133 0xf5f 0x1325 0x100, 2
2016-12-22 21:44:24.957199+0900 0xde9d Default 0x0 0 kernel: (IOUSBFamily) USBMSC Identifier (non-unique): 4C530006070617103092 0x781 0x5576 0x127, 2
2016-12-22 21:47:07.436727+0900 0xdecb Default 0x0 0 kernel: (IOUSBFamily) USBMSC Identifier (non-unique): FF05080500133 0xf5f 0x1325 0x100, 2
Flag: 2016-12-22-21:47:07