The direction of the flies(Housefly)

Why do flies move crosswise and polygonally? Does the length of the flight path and the angle they turn mean?

• I assume this was observed in a small room and the turns were when they approached an obstacle. They use optic flow for obstacle avoidance which kind of explains the straight lines. The retracing might be just be a neural adaptation to not get stuck in a space while still largely still traveling in the intended direction. Was the opening in the curve the direction of the door that the fly entered the room through. Commented Jun 8, 2023 at 15:43
• This was observed in a small room. All the doors were closed. I watched this for over an hour. Don't they get tired? Commented Jun 8, 2023 at 18:11
• Air is much more viscous when you're the size of a fly than when you're larger which makes flight much less energetic. It's more like they're swimming than flying. If my understanding of Reynolds numbers are correct, a fly in air is swimming 5000 more than a human is in water (Reynolds number being the ratio of inertial to viscous force and it being around 1 million for a human and 200 for a fly). Commented Jun 8, 2023 at 18:26
• Thank you, @DKNguyen Commented Jun 8, 2023 at 19:26