Fortunately, we have a recently published key for Dasysyrphus - this keys out to D. laticaudus.

The fact that the maculae on tergites 3-4 don't reach the abdominal edge rules out venustus, limatus, and the intrudens species complex. The dark gena and abdominal markings rule out creper, lotus, and richardi (as does the location). The shape of the pattern on sternite 2 (thanks for the upside down pic!) and location rule out pinastri. The maculae not being constricted rules out amalopis and occidualis. Light profemur rules out nigricornis. Range rules out pauxillus and pacificus.

On this female, I can somewhat see the outer edges of the maculae on tergite 2 extending forward and reaching the abdominal edge, which is a key characteristic for D. laticaudus.

Thanks so much Kelsey for all these explanations..

Thanks Ron..