By comparison, non-Calyptratae flies' takeoffs lasted about 0.039 seconds (39 milliseconds) and required about four wingbeats, according to the study.

First fossil of an oestroid fly (Diptera: Calyptratae: Oestroidea) and the dating of oestroid divergence. PLoS ONE, 2017 DOI: 10.1371/journal.pone.0182101 ...

A group of flies known as Calyptratae, which includes houseflies and blowflies, rhythmically move these wings when standing. “We know that they’re the only group that does this,” says Yarger.