Thanks, tf68!
I had tried the reset button before with no success.
Using /dev/ACM0 doesn't make any difference (with or without reset).
The Arduino actually responds to either address by flasing the LED once when starting the transmission but doesn't actually upload.
Pushing the reset button has not been necessary on any of the other boards or when transmitting to the Micro from the Arduino software.
I'm going to create the file once more even though I had done this before several times.
Maybe something in the programming is wrong that causes it to work from the Arduino but not from avrdude directly? But I had used the same programming for the other boards as well ...
What is -cavr109 and where does it go in the command line?
Does it replace anything else in there?