Hover flies
Hover flies hover over flowers before landing. They generally look like bees and wasps, but they’re flies.
Tufts Pollinator Initiative has a chart of common hover flies of New England, most of which would be common here in CNY as well.
Tachnid fly
These sometimes parasitize monarch pupas.
Sarcophaga flesh-eating fly
Horrible-sounding name!
Green bottle fly
Beautiful iridescent green.
Tiger bee fly (Xenox tigrinus)
An intriguing-looking insect that was resting awhile on our backyard chairs.