Found perching on the rock face of a road cut in an opening in mixed Redwood-Douglas Fir-Oak woodland near the crest of the Santa Cruz Mountains.
This keyed to genus Syrphus
in the Manual of Nearctic Diptera(1)
. In particular, long yellow hairs are visible on the lower calypter in the full-size image
(mentioned as the primary character at couplet 3 in the MND(1) Syrphidae
key)...if you can figure out where to look!! The lower calypters appear just above and anterior to the bright yellow halter knobs in the photo...and their long, yellow & blackish hairs partially obscure the halteres.
[Postscript (12/23/14): Apparently the hairs intended to be described in couplet 3 of the MND are not quite visible here...see the comments below.]
I used Vockeroth(2)
to attempt an ID to species. Vockeroth mentions that even though his treatment is for the nearctic Syrphinae north of the lower 48 states of the US, in still includes all the US species except for those of 5 particular genera (and Syrphus
is not among those 5). Using his key to Syrphus
, it seems the bare eyes; the fact that the yellow bands on T2-T4 don't quite reach the lateral margins; and the coloration of face, frons, and legs...lead to either S. opinator
or S. intricatus
(both of which are said to occur in California). The characters given to separate those two species depend on the distribution of microtrichia (= microscopic hairs) on the wings, which look like subtle "stippling" even at maximum dissecting microscope magnification...and are practically impossible to discern in a typical BugGuide photo. However, since Vockeroth(2)
states that "S. intricatus
and S. opinator
may be a single variable species", and Chris Thompson indicated S. opinator
is the common species in central California (see info page)...it seems most appropriate to post this under the latter for the purposes of BugGuide.
The holoptic eyes indicate this is a male.