Helophilus fasciatus.
Helophilus latifrons has the basal two antennal segments black

The Good News is there's only 3 species of Helophilus in southern Ontario. The Bad News is you need a good view of the face to separate them. Jeff Skevington told me last year that:
"obscurus is the only Ontario species with a shiny black media stripe on the face (the other two have a shiny yellow to reddish brown stripe). The key couplet to separate the other two species goes as follows:
- male vertex narrow, wholly black pilose, female front and vertex entirely black pilose.... fasciatus
- male vertex broad, partially yellow pilose, female front broadly yellow pilose.... latifrons"
The Really Bad News is there's 2 additional species in central and northern Ontario, and there's 28 more in North America.