Eristalis dimidiata, a very dark individual--many have some one or two yellow stripes on the abdomen. This is an Eristalis one sees during cool weather in the fall, as well as pretty early in spring, according to references. (I can only recall finding it in the fall, when it is quite common in my area.) It is heftier than the yellow-and-black Eristalis transversa in the adjacent photo.