Why do flies circle around lampshades

[Guinnessman1974]

A fly was circling around a ceiling light shade today, and I wonder why do they do this?

[Jason Green]

Evening GM,

I assume they are either attracted by the heat or light, and use it as a good vantage point from which to find females. The thing when it looks as if they are bouncing off invisible walls must be them patrolling their territory perimeter-to-perimeter - ever notice one shoot-off only to return? I assume it's when the dominant one realises there's an intruding male and sees him off.

I believe that, from noticing the same flight pattern over the Bramble in the garden ('bouncing' off invisible walls...) and never seeing this flight control in Muscids (who would be the usual indoor suspects, such as Musca domestica, et al) that they could be from the Fanniidae family. Still, I don't know which 'familiar' domestic flies hail from this group so I won't be too particular. A photo of an adult showing wings would help should you wish for a possible ID...

Hope this helps.

Take care,

Jason

[Guinnessman1974]

Hi Jason

Thanks for the info. Territorial reasons do make sense. Also, yes, I have noticed before when a fly might become aggressive to another one which intrudes in it's 'airspace' as it were.

Note also that the light was switched off at the time! Maybe they also use it as a reference point to aid navigation?

[Jason Green]

...aid to navigation - good point.

[Meta menardi]

I was told (or read, who knows) that flies fly towards smells and towards light. If you have a kingfishers nest, or some such, they fly in until the need to fly to the light takes over, fly out till the need to fly to smelly stuff takes over, fly... you get the picture. A tube, some gorgonzola and a torch, and you could have an answer.

[Meta menardi]

Oh, and a fly.

[Guinnessman1974]

However, again note that the light was switched off at the time, so light is not a factor. It seems to be the shape of the lampshade that is the point.