I've read discussion and 1) see no hairs and 2) mesonotum seems shiny.

What do you see that I don't?

Thanks :)

So I do these mostly on jizz, so general appearance.
In europe the species of Syrphus have a relaive dull thorax, but I've seen more shiny ones from your part of the world.
The main detail I look at in this case are the yellow bands on the abdomen and whether there's a margin on the sides of the abdomen, in Eupeodes these are different.
Greetings

I didn't trust so small a photo to see margins but now looking at it again I think you are right.

Chris Thompson says it is probably Syrphus opinator.

Alice, did Chris Thompson seem confident enough regarding the ID on your image that we should create a new guide page, or was that just his best guess?

"Syrphus torvus has hairy eyes (more in the male than in the female),
but in none of these pictures you can see this character.

Syrphus opinator is the common species in central California. Syrphus
torvus is more northern and early spring only.

Syrphus opinator has the abdominal fasciae (bands) restricted to the
sides and isolated from the margins. This appears to be the case in
these pictures.

There are other characters such as the distribution of microscopic hairs
on the wing that separate these species. So, again this can not be
checked in your pictures."

Alice, I'm pretty new to being an editor and I'm definitely not an expert on syrphids, so I'm not exactly sure how to proceed in this case. From Chris' comments it sounds as though S. opinator is the most likely candidate, but since there still seems to be some possible uncertainty I am leaving it at genus-level for now. As I understand things, it is incredibly difficult to make a species ID on this genus from features apparent in photographs alone (with the exception of the hairy eyes found in S. torvus).

I have been following all of your syrphid posts and you seem to have pretty good success with them, so perhaps it will be possible to get some more shots of this species which show the eyes in a little more detail? In an effort to not let this useful post go to waste, I have included a link to Chris Thompson's comments under the Identification section of the Info page for this genus.

Would you like me to post the other Syrphus images that he is referring to?

I have my own site where I have a Syrphid page .

Alice, I changed my mind and decided to go ahead and create the page. After all, the worst that can happen is someone will object and we can put things back the way they were. So, yes, do go ahead and upload any other images you have of this species to the newly created page. I will add more resources to the Info page sometime soon.