Eristalis stipator

Eristalis stipator, the yellow-shouldered drone fly, is a species of hoverfly native to North America.

[1][2][3][4] It is abundant in western North America, with a few scattered records in the east.

[4] E. stipator varies in appearance, with darker individuals sometimes resembling Eristalis dimidiata.

[4] Their setae give the appearance of coming to a point in the center of the third and fourth tergites.

Females have a frons that is entirely silvery-white, except for a black median stripe, running from the base of their antennae to the end of the head.

An E. stipator with its abdomen visible, showing the pile/setae on the third and fourth tergites forming narrow bands that come to a point, and showing that the third tergite is shiny black.
A picture of a female E. stipator. The fly's face is overall silvery-white, except for a narrow black median stripe that extends vertically along the middle of the face, from the antennae (which are about halfway up the face) upwards.
A female E. stipator showing the distinctive face of females of this species - the frons is extensively silvery-white setose except for a narrow black median stripe.