Upload fails using Virtualbox and Windows 7 on Mac

I have a new iMac running El Capitan. I have installed the latest IDE and everything is great.

I have installed Virtualbox version 5.0.8 and Windows 7 Home Premium 64 and the Arduino IDE on the windows in the VM. When I plug in an ATMEGA2560 into the USB it is recognized as COM 3 in the Windows OS.It also shows up as Com 3 in the device manager and the IDe seems to like it. Attempting to upload Blink fails in the VM and times out.