I got the piece from a friend early this summer. It has been stored in the attached garage until recently (about a month ago) when I placed it on the lumber rack. I'll give the friend a call tomorrow to let him know. (Not you, Ned, take a deep breath, this piece was from Sean.)
There was some exposed bark on the piece in question. With the possible exception of the bark, no holes were visible prior to milling. This is the first I've seen such a larva - what sort of inspection needs to be done to check out the other wood on the lumber rack?
The piece in question has been disposed of.
Thanks for the quick reply.