A trace of the oxygen concentration in the measurement chamber:
As soon as a bee enters the chamber the O2 concentration (green curve) drops - because the bee consumes part of the O2 to keep her flight muscles heated.
A hot thorax (from ˜33ºC up to 45ºC!) allows her to keep the suction velocity high.
The concentration increases to the initial level when the bee leaves the chamber.
You see 5 visits at the artificial flower.