I'm sure you remember the last Spilomyia species I briefly mentioned here yes? Well this one ( Spilomyia fuscata ) is mimicking the Baled Faced Hornet and if I didn't know better I would think it was one. Damn things are geniuses not to mention epic.
I couldn't find too much on any specific species but there's some on S. sayi:
Spilomyia sayi is a common species of North American hoverfly. It is a wasp mimic.
Adults 12-16 mm in length, are seen from June to October in the northern part of their range. Males engage in hilltopping, where they find high ground to await females. Larvae are found in decaying heartwood of deciduous trees.
This is from Wikipedia. There doesn't seem to be too much on them for some reason.
It's disappointing since I find these so fascinating. Happy August!