On deck of house. Large dark dipterid. Not unfamiliar.
Tiger Bee Fly
A large fly, with patterned wings.
I see them often around the house. Recently learned that they prey on Carpenter Bee larvae, which we have in abundance.
Tiger Bee Fly flying around my front porch lights just before a thunderstorm. 10pm
This tiger bee fly was observed interacting with a second of the same species, as well as resting on a wooden table repeatedly over the period of about 15 minutes.
Xenox tigrinus (Diptera: Orthorrhapha: Asiloidea: Bombyliidae: Anthracinae: Anthracini). Burke, Fairfax County, VA 04 September 2012