This moth appears to be a Tiger Moth of family Arctiidae. It has a red eye,
feathery antennae, a furry red "cheek patch" and red bands on the foreleg.

The experts at BugGuide.org have suggested that it could be Leptarctia
californiae, a species found from the Rockies west.
It was resting, not feeding. Some Arctiids are known to not feed as adults.

The BugGuide.org website, with thousands of photos of hundreds of moth
species, has nothing like it. CalPhotos has several species of Tiger Moth,
some with red cheek patches, but no species like this one, and no Leptarctia.

It was found at Edgewood Reserve in San Mateo County, California. The
location is the foothills of the Coast Range, south of SF about 30
miles. The date is mid-April at the peak of the wildflower season.