I recently photographed two flies that are obviously bee mimics. They both look like bees–one a honeybee and the other a bumblebee. Both sort of pump their abdomens–sending a not so subtle message that they have a stinger and are not afraid to use it. Of course, it is all bluff.
The bumblebee mimic is Eristalis anthophorina.
It really does look like a medium-sized bumblebee. Even the back leg is enlarged like the pollen basket of a bumblebee.
The other fly is called a drone fly–Eristalis tenix. This is a very early non-native import into North America. It mimics the non-native honeybee.