This is interesting (not saying it isn't the weevil, because there are the leaf-mining signs) but just stumbled upon this Noctuidae attacking lilies in the western USA including California:

Stem Borer Attacking Lilies
http://jee.oxfordjournals.org/...

Edited to add, this from the same author as the evil weevil PDF.

It's around the same time too, 1942! I wonder if both pests are culprits?

Trying to find anything more about the moth, it's a valid name at least for the species epithet.

Emboloecia sauzalitae papaipemoides

http://www.nhm.ac.uk/our-scien...

http://www.gbif.org/species/11...

You can download or just open the pdf of an old book where the moth is described on pages 95 & 96, it lists California but doesn't give any other info.

https://www.google.co.uk/searc...

Emboloecia sauzalitae larvae are described on google books, it states they are "more or less general feeders".

https://books.google.co.uk/boo...

There's descriptions of them on the book but it would be a microscope job.

I did see one or two treatments that had moved it into the Papaipema - according to a book I have Papaipema come in the category of borers that push their frass out of the larval tunnel so that it accumulates beneath the tunnel entrance outside. I guess if it's a microscope job to determine the species, at least if Leslieray can catch a look at the culprit we'll be able to tell if it's a weevil or moth larva...

v.27, no. 6, p. 778-789.
Lange, W. H. A hitherto unreported noctuid stem borer of corn and

globe artichoke in California (Lepidoptera Noctuidae Emboloecia

sauzalitae Grt. ) . v. 28, no. 4, p. 288-290, illus.

https://archive.org/stream/ent...

There's a pdf too, reference pages above. (the pdf is only for v, 8)

https://ia800300.us.archive.or...

Papaipema came up when I looked for images.

Took a few more photos. The first one shows excrement collecting in the whole. Bummer. All the canes (4) show the grazing damage but no sign of egg, critters or any leaf damage. There are two smaller canes that have an old large cane stump with them. Should have been more large canes from there this year. Maybe that bulb was damaged by borers. Is this just one critters hole?

If it is the Lily Weevil, the chart shows when the overwintering larvae are inactive in chart A. Eggs laid around the end of April to beginning of May the following year, the article states it was 1st May for them. Newly hatched larvae active from around mid May or a little later which would be the grazing on the stems but it's a little early, I would expect some extension either end.

The first part of chart A gives overwintering larvae as inactive until mid July, I find that odd as you would think they would feed until pupating when the lily is in growth. I think they should have added activity within that period and if so then it would fit that the larvae has woken up and started to fatten up before pupating, that's what they do.

OR, it's the moth.